OCTOBER 1992, VOL 56. NO 4
-I__.
-
AORN JOURNAL
Pulmonary Autograft AN AORTICVALVEREPLACEMENT ALTERNATIVE Patricia A. Wright, RN; Ronald C. Elkins, MD edical science has been searching for the perfect substitute for the human heart valve for more than 30 years. Two primary categories of manufactured valves have developed from this search (Fig 1). The mechanical valve (ie, man-made valves that combine metal and fabric materials into various configurations of opening and closing discs or balls) and the bioprosthetic valve (ie, a tissue valve, usually porcine, that is sutured into fabric-covered metal or plastic stents) have been used extensively with considerable success.' Over the years, however, a number of complications have been noted with each type of replacement valve. Both types can be technically difficult to implant due to the bulk of the sewing ring. Also, residual flow gradients
M
remain because of altered blood flow patterns. The turbulence caused by this difference in the flow pattern can cause hemolysis of red blood cells. Patients have an increased risk of endocarditis following manufactured valve replacement. This risk is highest immediately after surgery and decreases to a constant, relatively low risk after six months. Homografts do not have this early increased risk but have a similar low, long-term risk for endocarditis. Patients who receive mechanical valves face a lifetime of anticoagulation that predisposes them to the risk of m a j o r h e m o r r h a g e . Anticoagulants also can cause birth defects or fatal hemorrhage in a fetus. They also pose a high risk of maternal and infant bleeding problems at delivery and can be transmitted to the
Patricia A. Wright, RN, CNOR, is organ procidrenient specialistlRN f i r s t assistant, Departmetit of Thoracic and Cardio\ascular Surgery. at the Uuii2ersity of Oklahoma Health Sciences Center, Oklahonia City. She earned her associate degree in iiiir.sing at the Uiiiveixity of Toledo (Ohio).
R o d C.Elkins, MD, is projessor and chief of Thoracic and Cardiovasculai~Si4i.gei.y at the University of Oklahoma Health Sciences Center, OkIahoma City. He earned his medical degree at the Unii9ersity of Oklahoma School of Medicine, Oklahoma City. 639
OCTOBER 1992. VOL 56. NO 4
AORN JOURNAL
Fig 1 . (Clnckuise fi-om upper left) bioprosthetic porcine valve, mechanical ball-in-cage valve, mechanical disc valve. composite mechanical disc valve with attached Dacron conduit.
nursing newborn. Mechanical valves can fail if one of the components breaks, or if the disc becomes fixed i n an open or closed position because of neointimal hyperplasia (ie, tissue growth on the valve). clot on the disc, or in surrounding structures (eg. the fabric-covered metal sewing ring. stems). Bioprosthetic valve durability also is a problem. These valves are predisposed to the formation of calcium deposits on the leaflets, especially in younger patients. These deposits render the valve stenotic, resulting in repeated valve replacement surgery. Each time a valve must be replaced. the procedure carries a higher mortality risk for the patient. In an effort to avoid the complications associated with mechanical and bioprosthetic valves and because cryopreservation techniques have improved. human heart valves (ie, homografts) are being used to replace valves in many patients.
Not everyone is a candidate for homograft valve replacement, however. T h e selection of a replacement valve depends on many individual patient factors (eg. age, replacement/failure risks, risks of life-long anticoagulation).
Pulmonaiy Autografts
A
pulmonary autograft procedure is complex c a r d i a c surgery in which a .patient’s d e f e c t i v e aortic v a l v e is replaced by moving his or her pulmonary valve to the aortic position and reconstructing the right ventricular outflow tract using a cryopreserved pulmonary homograft. Donald Ross, MB, Ch.B, FRCS, pioneered the pulmonary autograft procedure in Great Britain in 1967 as an alternative method of aortic valve replacement. Ross used an antibiotictreated cadaver pulmonary valve and conduit to
OCTOBER 1992, VOL 56, NO 4
replace the patient’s pulmonary valve and artery, which was moved to the aortic position.2 Cadaveric valves stored in antibiotic solution must be discarded after two months if not implanted. Development of cryopreservation techniques (ie, preservation of human tissue in dimethylsulfoxide by freezing at -196 “C in liquid nitrogen) made pulmonary autograft surgery more feasible by increasing the “shelf life” of homograft valves thus making more valves of different sizes available. The cryopreservation procedure also has decreased the risk of disease transmission because extensive tissue cultures and serologic testing are done on each valve, and careful attention is paid to antibiotic techniques in the preservation pr~cess.~ In the 25 years following Ross’ initial work, follow-up investigation reveals excellent longterm results for patients receiving these autografts. Ninety-six percent of these patients did not experience endocarditis, and 93% were spared aortic valve incompetence due to technical errors in the valve.4
Pulmonary Autograjl Indications
T
e primary indication for a pulmonary autograft is severe congenital aortic stenosis. Patients who are candidates for pulmonary autograft may experience aortic regurgitation or mixed aortic stenosidregurgitation. Other candidates for this procedure are patients who need to have their mechanical or bioprosthetic valves replaced, especially if they have a previous history of subacute bacterial endocarditis. For patients with a life expectancy greater than 20 years, pulmonary autograft, using homograft valve replacement for the pulmonary component, offers an effective alternative to mechanical or bioprosthetic valves.
Benefits
T
he use of a pulmonary autograft procedure has several advantages. The patient’s pulmonary valve can withstand the greater pressures exerted by the arterial side of the heart and it can function in a manner
AORN JOURNAL
similar to the aortic valve. In addition, the autograft is more streamlined and less bulky than alternative valves which are sutured into and surrounded by a fabric-covered metallic sewing ring. Moreover, the autograft valve provides the same turbulence-free blood flow pattern as a native healthy valve because it is one. Longterm, longitudinal studies over the past 25 years have shown excellent freedom from reoperation due to valve f a i l ~ r eThere . ~ is even documented echocardiographic evidence of autograft growth in children? If necessary, it is far less risky to replace a homograft valve and conduit in the right ventricular outflow tract than to use a replacement valve (ie, mechanical, bioprosthetic valve) on the left side of the heart. The autograft pulmonary valve, when moved into the aortic position, is less likely to need replacement because it is the patient’s own viable tissue. The homograft is used to replace the pulmonary valve in the right side of the heart with its lower pressures where, if necessary, it can be replaced more easily and without the added risk that a surgical procedure on the left ventricular outflow tract poses to the coronary arterie~.~ Another of the major benefits of the autografthomograft procedure is the freedom from the risks of life-long anticoagulant therapy that mechanical valve replacement requires. This is particularly important in children and young adults, women of child bearing age, and in patients who may be non-compliant with anticoagulant therapy. Patients with a history of subacute bacterial endocarditis have fewer episodes of this following valve replacement with autograft/homograft than those who have had replacement with mechanical or bioprosthetic valves.* Homografts also do not have to be blood-group matched because their fibroblastic tissue does not cause rejection phenomena. Autograft valve replacement also has been shown to be effective in patients of many ages. For example, at the University of Oklahoma Health Sciences Center, Oklahoma City, 90 patients, ranging in age from 1 week to 59 years, have successfully undergone the pulmonary autograft procedure. 641
OCTOBER IOQZ. VOL 56. NO 4
\ O R N . l O C RN41.
Risks
T
he autogr~ift/honiograftprocedure is technically riskier because performing a n autograft procedure involves a double valve replacement. Special techniques used i n the procedure also increase the risk of potential problems. For example. i n one of the autograft techniques the surgeon reimplants the coronary arteries into the pulmonary c o n d u i t . When these arteries a r e implanted. their alignment must be flawless to ensure that they are not kinked or twisted. which could cause coronary occlusion.’ Bleeding also is a major concerti because of the extensive suture lines required by the procedure. To prevent bleeding. the surgeon must pay fast i d i o 11s at t e ti t i o n to the an as t om0 se especially on the posterior side of the aorta and pulmonary artery. as well as the coronary reimplantation sites.
efore a pulnionar!- autograft procedure is scheduled. the patient undergoes a left and right heart catheterization. The surgeon uses data from this test and echocardiographic data to confirm the patient’s diagnosis of valvular disease. The surgeon elicits a complete history from the patient and performs a physical examination. He or she orders a posterior/anterior and lateral chest x-ray and electrocardiogram ( E C G ) to be performed. and asks laboratory personnel to perform the following tests on the patient: complete blood count (CBC). biochemistr! profile. prothrornbin time (PT). partial thromboplastin time (PTT). urinalysis. and a type and cross-match.
A M?
pulmonary autograft procedure usually i\ elective although i n some cases it may be urgent. If the surgery is not
extremely urgent. the patient and his or her family will meet with a primary cardiac intensive care unit (CICU) nurse for preoperative teaching. This client/care giver contact presents the patient and family with an opportunity to ask questions and verbalize concerns. It also sives the CICU nurse a chance to meet the patient and assess any needs particular to that patient. The nurse gives the patient and family a tour of the CICU and explains what will be involved in postoperative care. A checklist is used ( T a b l e 1 ) a n d this is kept with the patient‘s chart to ensure comprehensive teaching. The perioperative nurse focuses his or her assessment on gathering infomiation from the patient regarding allergies, past medical and surgical history, current medications. physical or mental deficits. and the patient’s level of understanding regarding the planned procedure (Table 3 ) . The perioperative nurse also performs a baseline physical assessment of the patient’s skin condition. circulation, mobility, and ability to communicate. The nurse assesses the patient‘s family or significant others for their understanding of the planned procedure, anxiety level. and coping mechanisms, and answers any questions they or the patient may have.
efore the patient arrives in the OR. the perioperative nursing team prepares the OR suite for a routine cardiac procedure. The nurses ensure that all necessary equipment (eg. electrocautery. a defibrillator, a c a r d i a c p a c e m a k e r a n d c a b l e s , a slush machine. a cardiopulmonary bypass machine) are in the room. Sterile instruments for this procedure are gathered and include a basic chest set and valve tray that includes cardiac retractors ( e g , atrial retractors, aortic valve retractors) cardiovascular needle holders, and mechanical and porcine valve annulus sizers. Sterile back table. Mayo stand, and patient drapes required for a cardiovascular procedure are gathered. Additionally. an inventory list of
OCTOBER 1997. VOL 56. NO 4
AORN JOURNAL
Table 1
Preoperative Baseline Physical Assessment Neurological Pupils Grips Coordination Speech ~
Level of Consciousness/Orientation
Cardiovascular Hypertension yes no Blood pressure Pulse Edema Jugular vein distention Peripheral vascular disease Bruits in carotid/femoral arteries ECHO data Heart cath data
Pulmonary Breath sounds Arterial blood gases: PHPCOZ PO? HCO, 0,Saturation ~
History of smoking Packs per dayUse of 0, at home Incentive spirometer mL
Musculoskeletal/Skin History of fractures Arthritis Facial fractures Skin ulcers
Renal Previous 24 hr intake output BUN Creatinine Last void: rnL History of dysuria yes Foley inserted: yes -no date time
time no
Gastrointestinal Bowel sounds Abdominal assessment Presence of bruits Last bowel movement
Pspchosocial Family present for preoperative teachingVerbalized understanding: Patient Family Education level: Patient Family Knowledge of illness Previous hospitalizations
Endocrine History of diabetes Last glucose Insulin AM/PM History of hepatitis Previous thyroid surgery
units
643
OCTOBER 1992, VOL 56.NO 4
AORN JOURNAL
Table 2
Preoperative Teaching Checklist Date CICU tour Explanation of postoperative care coughing/deep breathing splinting abdomen with pillow cardiac monitoring frequency of vital signs/nursing assessments equipment IV pumps 0 2 saturation monitors datascope arterial lines pressure monitor invasive lines pulmonary artery line endotracheal tube Foley che5t tubes wound sites chest exercise legs ankles incentive spirometry therapy turning lavage suctioning wound care explanation of alarms
Time
Nurse
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Fig 2. The pulmonary artery and valve are excised from the right ventricular outflow tract. (Figures 2 through 10 by M. LaWaun Hance, SA, PA-C)
the pulmonary homografts that are available in the nitrogen freezer is posted in the room for later reference. The surgeon will refer to this list when choosing the appropriately sized homograft. Once the flat surfaces and lights are damp dusted, packs and instrument trays are arranged in the room and opened. The nurse places a temperature regulating mattress on the OR bed, sets the temperature at 37 "C (98.6 OF), and covers the mattress with a bath blanket and lifting sheet. The bath blanket protects the patient from direct contact with the temperature regulating mattress and the lifting sheet allows the surgical team to move the patient more easily. The perioperative nurse also checks on the availability of blood and blood products that have been ordered preoperatively and helps anesthesia personnel obtain the necessary anesthetic drugs and equipment, When possible, needle, sponge, and instrument counts are completed before the patient is brought into the
room to ensure a quiet atmosphere.
Preoperative Patient Care
T
he perioperative nurse meets the patient and his or her family in the preanesthetic holding area. After confirming the patient's identification, assessing his or her condition, checking the chart for a signed consent form for the appropriate operative procedure, and the presence of ordered laboratory reports, the nurse transports the patient to the OR suite. The nurse helps the patient transfer from the cart to a supine position on the OR bed, and makes him or her comfortable with warm blankets. A safety belt is placed across the knees. Pediatric patients may be held on the anesthesiologist's lap for induction if he or she feels it would make the child less frightened and more cooperative. The nurse helps the anesthesia team to 645
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Fig 3. The aorta is cross clamped, cardioplegiasolution given, and the aortic valve is removed.
Fig 4. The pulmonary artery and valve are lowered into the aortic annulus.
induce and intubate the patient, and to insert IVs, a radial arterial line and a pulmonary artery (ie, Swan-Ganz) catheter cordis. A cordis is the port inserted into the internal jugular vein through which fluids can be given intraoperatively or through which a pulmonary artery catheter can be inserted in the CICU. A pulmonary artery catheter is not inserted preoperatively because it would interfere with removal of the pulmonary valve and artery, and anastomosis of the pulmonary homograft. A doublelumen catheter monitoring line may be used in a child. In adults, these lines may be inserted in the preanesthetic holding area; in children, they are inserted after induction. The perioperative nurse inserts a Foley catheter that contains a special temperature monitoring probe. This cathetedprobe monitors the patient’s urine output as well as core temperature during the procedure. A regular Foley may be used in combination with a rectal temperature probe if a catheter with a temperature probe is not available. With the patient in a
supine position, the nurse pads all bony prominences with foam “egg crate” material, tucks the patient’s arms to his or her side using the lifting sheet to secure the patient’s arms without occluding arterial and venous lines. The nurse places an electrosurgical unit dispersive pad on the patient’s buttocks or anterior thigh. A cage type tray, similar to an ether screen but with a tray across the top, is positioned over the patient’s face to prevent drapes and surgical personnel from contacting the patient’s face.
Surgical Procedure
A
fter satisfactory induction via general anesthesia, the nurse preps the patient from chin to knees, and from side-toside to the mid-axillary line, with alcohol. The surgical team drapes the patient with sterile towels and an iodine-impregnated adhesive wound drape. This is covered by a sternotomy sheet. The surgeon carries the incision down to the sternum and after performing a median ster647
AORN JOURNAL
OCTOBER 1992, VOL 56, NO 4
Fig 5 . An aortic punch is used to make two button-shaped holes in the pulmonary conduit.
Fig 6. The periphery of the button-shaped holes is sutured around the coronary ostia, and the distal suture line between the pulmonary conduit and the aorta is completed. 648
OCTOHEK 1992. VOL 56. NO 4
notomy, he or she opens the pericardium and uses pericardial stay sutures to maintain access and a clear view of the heart. The surgeon places a double purse string suture in the ascending aorta and two separate purse string sutures in the right atrium. The anesthesiologist heparinizes the patient and the surgeon cannulates the aorta. He or she then cannulates the superior and inferior vena cavae through the right atrium and the perfusionist begins cardiopulmonary bypass. With the patient on bypass, the perfusionist begins the cooling process, and the temperature regulating blanket is set to cool the patient. Routinely, patients are cooled to 22 "C (71.6 O F ) . The surgcon inserts a left ventricular vent through the right superior pulmonary vein to aid in decompression of the heart and to cnhancc the ability to see once the aorta is opened. In an adult, the aorta is cross-clamped and the surgeon administers approximately 1000 mL of oxygenated, cold blood cardioplegia solution through the aortic root to arrest the heart. Less cardioplegia is used in a child. Occasionally it is necessary, due to aortic insufficiency, to give retrograde cardioplegia solution through a cannula inserted via a right atriotomy into the coronary sinus. Aortic valve insufficiency prevents the valve from closing normally and allows cardioplegia solution to flow into the left ventricle rather than into the coronary system. This would not properly cool the entire heart, thus retrograde cardioplegia is used. T o maintain myocardial temperature below 12 "C (53.6 O F ) , additional cardioplegia solution is given every 30 minutes either retrograde or directly into the coronary ostias and the heart is packed in saline slush. The surgeon places an insulation pad between the heart and the pericardial sac to prevent phrenic nerve damage from the cold slush. A myocardial temperature probe is inserted into the myocardium to monitor heart temperature during cold arrest time. An aortotomy is performed distal to the aortic valve, and the surgeon inspects and removes the valve. He or she then opens the pulmonary artery at the takeoff of the right pulmonary
AORN JOLKNAL
artery and inspects the pulmonary valve. Once the surgeon determines that the pulmonic valve is normal, he or she enucleates the valve and artery from the right ventricular outflow tract. Extreme care is taken to protect the left coronary artery and the first septa1 branch of the left anterior descending artery during removal of the pulmonary conduit and valve because of their proximity to the dissection line. During autograft/homograft procedures the perioperative nurse maintains the operative records, helps anesthesia personnel monitor patient urine output, blood loss, temperature, and cardiac rhythm.
Autograft Techniques
A
t this point in the procedure, the surgeon can use one of two autograft tech.niques depending on the pathology presented by the patient.'O The intra-aortic implant technique. With this technique, the surgeon removes the aortic valve (Figs 2, 3, and 4), trims the pulmonic valve and conduit, and sutures it into the annulus of the aortic valve. He or she uses an aortic punch to make two button-shaped holes in the pulmonary artery (Fig 5). The surgeon then sutures the periphery of the two button-shaped holes around each coronary ostia (Fig 6). The aortotomy is then closed, completely enclosing the pulmonary autograft inside the aorta (Fig 7). The intra-aortic technique is the procedure of choice when possible. The root replacement technique. Using this technique, the surgeon removes the coronary artery ostia from the aorta with a buttonshaped portion of aortic wall (Fig 8). The aorta is opened at least one cm distal to the right coronary artery in a transverse manner. He or she sutures the pulmonary valve and artery onto the top of the left ventricle, situating the autograft so that the left coronary ostia is centered in one of the pulmonary valve sinuses. The surgeon makes a hole in the pulmonary artery (Fig 9) using an aortic punch and reimplants the left coronary artery button into the button hole with a running
cr 649
AORN JOURNAL
OCTOBER 1992, VOL 56, NO 4
Fig 7. The final result showing the over sewn aortic cannulation site, closed aortotomy, and interposed pulmonary homograft.
Fig 8. The coronary ostia are removed from the aorta on a button-shaped portion of aortic wall. 652
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Fig 9. The pulmonary valve and artery are sutured onto the top of the left ventricle. An aortic punch is used to make two button holes in the pulmonary conduit. The coronary ostia buttons are sutured into the button holes.
Fig 10. The completed root replacement showing the patient’s pulmonary artery in the aortic position and the pulmonary homograft replacing the native pulmonary artery. 653
OCTOBER 1992, VOL 56. NO 4
AORN JOURNAL
Fig 11.The pulmonary homograft after removal from the nitrogen freezer and thawing. suture. He or she completes the distal suture line between the pulmonary artery and the ascending aorta (Fig 10). After distending the aorta with cardioplegia solution to identify the proper location to implant the right coronary artery, the surgeon reimplants the right coronary button as the left was done. Root replacement has been the procedure of choice in patients with a small aortic annulus, a dysplastic annulus and significant subvalvular stenosis, significant abnormalities involving one or more of the coronary sinuses, o r in patients with coronary ostia that a r e 180 degrees opposed. Polypropylene suture is used for suture lines on the pulmonary autograft and pulmonary homograft anastomoses in adults. In children, absorbable 5-0 polydioxanone suture material is used to allow for growth of the pulmonary autograft, and polypropylene suture is used on the pulmonary homograft anastomoses. 654
Pulmonary Homograft Anastomoses
w
en the autograft has been completed, the surgeon removes the aortic cross clamp. He or she checks the aortic suture lines and the appropriately sized pulmonary homograft (ie. similar in size to the aortic annulus), which has been selected during the pulmonary autograft anastomosis, is thawed. When the surgeon chooses a pulmonary homograft from the posted inventory list, the nurse removes the homograft from its slot in the nitrogen freezer. He or she wears insulated gloves to protect the skin against severe burns that can be caused by contact with either the packaged homografts or the liquid nitrogen in the freezer. The nurse keeps the homograft package at room temperature for five minutes and then immerses the triple-wrapped package in a 3L,
OCTOBER 1992, VOL 56, NO 4
42 "C (107.6 O F ) , water bath until the solution in which the homograft is packed turns to slush (eg, 15 to 20 min). The circulating nurse monitors this thawing process, and when the homograft is ready to be transferred to the sterile field, he or she opens the two outer plastic wraps. The scrub nurse removes the inner sterile package, cuts open the top, and places the homograft into 1 L of room temperature 5% Dextrose and lactated Ringer's solution for its final rinse. He or she gently agitates the homograft in this solution for five minutes. When thawed and rinsed, the surgeon cuts a small tissue sample from the homograft to be sent for culture and sensitivity and carefully examines the homograft to be sure the valve is competent and the conduit is of good quality (Fig 11). The surgeon inspects the myocardium in the area of the excised pulmonary homograft for bleeding vessels and obtains hemostasis. He or she then trims the homograft and sutures the proximal end onto the right ventricular outflow tract, taking special care with the region of the first septa1 perforating artery. The distal end is sutured to the native pulmonary artery with a running suture. During the pulmonary homograft anastomoses, the perfusionist initiates rewarming of the patient. This is accomplished by warming the blood in the cardiopulmonary bypass circuit as it is returned to the patient and by setting the temperature regulating mattress to 37 "C (98.6 OF).
Upon completion of the anastomoses, the surgeon evacuates air from the apex of the heart with a needle. He or she removes the cardioplegia cannula and over sews the insertion site. Once the patient reaches 37 "C (98.6 O F ) , bypass is discontinued, the surgeon decannulates the patient, and the anesthesiologist administers protamine sulfate to reverse the effects of heparinization. The surgeon inspects all suture lines and obtains hemostasis. If the patient's heart does not revert to sinus rhythm, defibrillation may be necessary once the patient is rewarmed. The surgeon may place temporary epicardial pacing wires if there is a problem with the patient's heart rhythm. When
AORN JOURNAL
the patient is hernodynamically stable, an intraoperative echocardiogram can be used to verify autograft function. The surgeon inserts one or two mediastinal/pleural chest tubes and the scrub nurse connects them to a chest drainage system that is attached to 20 cm Hg suction. The surgical team closes the sternum with wire suture followed by routine closure of subcutaneous tissues and skin. The circulating nurse telephones a report to the CICU primary nurse approximately onehalf hour before the patient is scheduled for transport. This alerts the CICU nurse of the patient's condition and the need for additional patient monitoring equipment. After skin closure, the perioperative nurse assists the scrub nurse with dressing the patient's wound and preparing the patient for transport to the CICU. The nurse covers the patient with warm blankets and helps the anesthesiologist and surgical team to move the intubated patient to an ICU bed for transport to the CICU. The nurse assists anesthesia personnel in transporting the patient to the CICU. On arrival in the CICU, the perioperative nurse gives report to the CICU primary nurse.
Postoperative Care
W
hen the patient is admitted to the CICU, the immediate goal is to maintain or stabilize the patient's vital signs and prevent postoperative complications such as hemorrhage or hypotension. The surgeon may insert a pulmonary artery catheter to monitor an unstable patient, although this is not routine. If the patient remains stable, the anesthesiologist or CICU medical staff remove the patient's endotracheal tube the morning following surgery, and on the second postoperative day, the patient is transferred to the surgical ward. The surgeon uses a postoperative echocardiogram, done within 10 days of the procedure, to evaluate valve function. In a patient who experiences no complications, the hospital stay averages seven days. The surgeon discharges the patient with post655
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
surgical instructions for a gradual return to normal activities of daily living. Heavy lifting is prohibited for six weeks. The patient is asked to return for a follow-up visit to the clinic o n e week after discharge with instructions to have a P A a n d lateral c h e s t x - r a y a n d EKG d o n e before the clinic appointment. Patients are seen a g a i n in o n e m o n t h . E c h o c a r d i o g r a m s a r e scheduled at three and six months in conjunction with clinic visits and then yearly.
Summury
I
n selected patients, the pulmonary autograft procedure utilizing cryopreserved h o m o grafts for reconstruction of the right ventricular outflow tract is becoming an increasingly popular aortic valve replacement alternative. Longitudinal statistical reports s h o w that patients need reoperation less often with this procedure. Because the valve is autogenous tissue, all indications to date show that the valve continues to function for extended periods of t i m e in a l l p a t i e n t s a n d can a c c o m m o d a t e growth in children. At the same time, transfer of the pulmonary valve to the aortic position provides a natural valvular flow pattern a n d freedom from the degenerative changes associated with bioprosthetic valves or the need for anticoagulation associated with mechanical valves. Notes 1. D Graf, L Gonzalez-Lavin, “The homograft: A new dimension for cardiac valve replacement.” AORN Journal 48 (November 1988) 911-917; P Stelzer, R C Elkins. “Homograft valves and conduits: Applications in cardiac surgery.” Cui-renr Problems in Surgery 26 (June 1989) 381-452. 2. D Ross. “Replacement of the aortic valve with a pulmonary autograft: The “switch” operation.” Anrials of Thorucic, Surgery 52 (December 1991) 1346-1350. 3. M O’Brien et al. “The cryopreserved allograft aortic valve,“ Journal of Cardiac Surgery 1 (March 1987) 153-167. 4. R C Elkins et al. “Pulmonary autograft replacement in children: The ideal solution?” Unpublished manuscript, presented at the American Surgical Association annual meeting, Palm Desert CA, April 4-8. 1992. 656
5. A Robles et al, “Long-term assessment of aortic valve replacement with autologous pulmonary valve,” Annals of Thoracic Surgery 39 (March 1985) 238-242; D Ross, “Pulmonary valve autotransplantation (the Ross operation),” Journal of Cardiac Surgery 3 suppl (September 1988) 313-319. 6. H Murata, “A study of autologous pulmonary valve replantation,” Nippnn Kyobu Ceka Gakkai Zasshi 32 (February 1984) 144.153. 7. G Gerosa, R McKay, J Davies, D N Ross, “Comparison of the aortic homograft and the pulmonary autograft for aortic valve or root replacement in children,” Journal of Thoracic Cardiovascular Surgery 102 (July 1991) 51-61. 8. J K Kirklin, A D Pacifico, J W Kirklin, ”Surgical treatment of prosthetic valve endocarditis with homograft aortic valve replacement,” Journal of Cardiac Surgery 4 (December 1989) 340-347; C Yankah, R Hetzer, “Valve selection and choice in surgery of endocarditis,” Jour-naf of Cardiac Surgery 4 (December 1989) 324-330; J K Lau et al, “Surgical treatment of prosthetic endocarditis: Aortic root replacement using a homograft,” Journal of Thoracic Cardioiiascular Surgery 87 (May 1984) 7 12-716. 9. R A Hopkins, J St Louis, P Corcoran, “Ross’ first homograft replacement of the aortic valve,” Annals o f Thoracic S u r g e r y 52 (November 1991)1190-1193. 10. R C Elkins et al, “Pulmonary autograft replacement of the aortic valve: An evolution of technique,” Journal of Curdiac Surgery 7 (June 1992) 108-116; D Ross, “Technique of aortic valve replacement with a homograft: Orthotopic replacement.” Annals of Thoracic Surgery 52 (July 1991) 154-156.
OCTOBER 1992. VOL 56, NO 4
4 0 R N JOL RNAL
hxamination PULMONARY AUTOGRAFT
1.
2.
3.
4.
5.
6.
658
Two primary categories of manufactured valves have evolved to replace defective heart valves. What are they? a. extruded plastic and Dacron b. mechanical and bioprosthetic c. ring and leaflet d. residual flow and gradient Manufactured valves can be technically difficult to implant because a. The sewing ring is too small. b. The sewing ring is too bulky. c. The sewing ring is easily damaged. d. There is no sewing ring. Patients who receive mechanical valves face a lifetime of and risk major a. surgery: bankruptcy b. anticoagulation; hemorrhage c. antimicrobial therapy; drug reactions d. immunosuppressive therapy; organ rejection Bioprosthetic valves are predisposed to on the leaflets which make the valve a. neointimal hyperplasia; dysfunction b. fat deposits: remain open c. calcium deposits; stenotic d. potassium deposits: remain open Manufactured valves create residual flow gradients. This turbulence causes what? a. audible bruits in the chest b. neointimal hyperplasia c. hemolysis of red blood cells d. high patient mortality Pulmonary autograft procedures (PAPs) are done to reconstruct the patient’s a. defective aortic valve
b. left ventricular outflow tract c. right ventricular ouflow tract d. defective pulmonary valve 7. Pulmonary autograft procedures are indicated for patients with 1. severe congenital aortic stenosis 2 . aortic stenosis and/or regurgitation 3. hypoplastic left hearts, 4. manufactured valves and a history of subacute bacterial endocarditis a. 1 and 4 b. 2 a n d 3 c. 1, 2, and 4 d. 2 , 3, and 4 Patients with a life expectancy of greater 8. than 20 years are good candidates for a bioprosthetic valve. a. true b. false 9. Studies have shown that patients with homograft procedures have less and a. rejection phenomena: bleeding b. aortic valve incompetence; bleeding c. endocarditis; aortic valve incompetence d. infection; pulmonary valve incompetence 10. Patients with mechanical or bioprosthetic valves who have histories of subacute bacterial endocarditis are good candidates for PAPs. a. true b. false 11. W h y i s a P A P considered technically riskier? 1. It involves tissue from another person, and thus there is the risk of rejection.
OCTOBER 1992, VOL 56, NO 4
2. It takes longer, which results in increased anesthesia time and its associated risks. 3. The procedure involves a double valve replacement. 4. In one version of the PAP, the surgeon must reimplant the coronary arteries and can cause occlusion of them if he or she does this improperly. a. 1 and2 b. 2 a n d 3 c. 3 and 4 d. 2 a n d 4 12. Because the surgeon is working with the aorta and pulmonary artery, is a major concern. a. cardiac blood flow b. bleeding c. heparinization d. cardiopulmonary bypass 13. One advantage to the use of a pulmonary homograft over a mechanical or bioprosthetic valve is that the patient does not need a. surgery b. intraoperative heparinization c. postoperative anitcoagulation d. intraoperative cardiac bypass 14. The need for valve replacement is a problem with mechanical or bioprosthetic valves. Why are autografts/homografts better in this regard? 1. The homograft used to replace the pulmonary valve can be replaced more easily without the added risk that surgery on the left ventricular outflow tract poses to the coronary arteries. 2. Cadaver valves are easy to come by and do not need replacement. 3. The autograft pulmonary valve, when moved into the aortic position, is less likely to need replacement because it is the patient’s own viable tissue. 4. Only one valve is replaced, thereby reducing the number of valves that might need replacement in the future. a. 1 and 2 b. 2 a n d 3
AORN JOURNAL
c. 1 and 3 d. 2 a n d 4 15. Homografts do not need to be blood-group matched. Why? a. They can be replaced easily if rejected by the patient. b. Fibroblastic tissue does not cause rejection phenomena. c. Fibroblastic tissue cannot be bloodgroup matched. d. Homografts are the patient’s own tissue. 16. Pulmonary autograft procedures have been performed on patients who range in age from one week to 95 years. a. true b. false 17. The benefit of moving the patient’s pulmonary valve into the aortic position is 1. It functions in a manner similar to the aortic valve. 2. It is the only way to replace the aortic valve. 3. It can withstand the greater pressures exerted by the arterial side of the heart. 4. It takes less surgical time to do this. a. 1 and 2 b. 2 a n d 3 c. 1 and3 d. 2 a n d 4 18. Autografts are than manufactured valves and provide the same pattern as a healthy native valve. a. less expensive; electrocardiogram b. less bulky, turbulence-free blood flow c. more bulky; performance d. easier to sew; hemolysis 19. Long-term follow-up on pulmonary autograft patients shows less valve failure and need for reoperation. a. true b. false 20. Autografts have been documented to show in children a. problems b. growth c. retardation d. clotting problems 659
OCTOBER 1992, VOL 56, NO 4
21. Because bleeding is a concern with PAPS, what would be important for the perioperative nurse to assess? a. PT, PTT laboratory results b. history of anticoagulant therapy c. skin condition, presence of bruising d. all of the above 22. A PAP requires cardiac bypass cooling. What patient care should the nurse perform? 1. Protect patient's skin from temperature regulating mattress by using a bath blanket. 2. Insert a catheter that contains a temperature probe, or a standard rectal temperature probe. 3. Cover the patient with ice. 4. Ensure that sterile slush is available. a. 1 and 3 b. 1,2, and 3 c. 1,2, and4 d. 2 and 4 23. When removing the size homograft chosen by the surgeon from the nitrogen freezer what must the circulating nurse do? a. Wear insulated gloves to protect himself or herself from severe bums. b. Keep the homograft at room temperature for five minutes. c. Immerse the homograft in a 42 "C water bath for 15 to 20 minutes. d. all of the above 24. When the perfusionist warms the patient, what should the nurse be aware of? a. the possibility of malignant hyperthermia b. the possibility of convulsions c. the possibility of fibrillation d. the possibility of bums from the temperature regulating mattress 25. If the patient does not revert to sinus rhythm, what may be necessary? 1. defibrillation 2. heart transplant 3. temporary epicardial pacing 4. permanent cardiac pacing a. 1 and 3 b. 2 only
AORN JOURNAL
c. 2 and 4 d. 4 only Professional nurses are invited to submit clinical or managerial manuscripts for the home study program. Manuscripts or queries should be sent to the Clinical Editor, AORN Journal, 10170 E Mississippi Ave, Denver, CO 80231. As with all manuscripts sent to the Journal, papers submitted for the home study program should not have been previously published or submitted simultaneously to any other publication.
Student Nurses Join National League The National League for Nursing (NLN) has formed a partnership with the National Student Nurses Association (NSNA) and is offering student nurses the chance to join NLN for $30. The membership fee includes access to the new NLN Center for Career Advancement, discounts on NLN books, special rates on professional development programs, and a oneyear subscription to NLN's journal, according to a June 1992 NSNA press release. The special rate is valid until one year after graduation; however, proof of NSNA membership is required for the discount. The release states that NSNA members who join the NLN will receive all membership benefits except voting and office-holding privileges.
661
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Answer Sheet PULMONARY
P
lease fill out the application and answer form below and the evaluation on the back of this page. Tear out the page from the Journal or make photocopies and mail to: AORN Accounting Department c/o Home Study Program 10170 E Mississippi Ave Denver, CO 80231 Event # 935004
AUTOGRAFT
Mark only one answer per question
1 2 3 4
Session ## 5521
Program offered Oct 1, 1992
5
The deadline for this program is April 30, 1993.
6
1. Record your identification number in the appropriate section below. 2. Completely darken the space that indicates your answer to the examination starting with question one. 3. A score of 70% correct is required for credit. 4. Record the time required to complete the program 5. Enclose fee: Members $7; Nonmembers $14.
7 8
9 10 11
12
AORN (ID) # If nonmember, please provide Social Security
13
#
14
Name
15
Address
16
City
17
State
Zip
18
RN license and state
19
Florida license #
-I__.
-
AORN JOURNAL
Pulmonary Autograft AN AORTICVALVEREPLACEMENT ALTERNATIVE Patricia A. Wright, RN; Ronald C. Elkins, MD edical science has been searching for the perfect substitute for the human heart valve for more than 30 years. Two primary categories of manufactured valves have developed from this search (Fig 1). The mechanical valve (ie, man-made valves that combine metal and fabric materials into various configurations of opening and closing discs or balls) and the bioprosthetic valve (ie, a tissue valve, usually porcine, that is sutured into fabric-covered metal or plastic stents) have been used extensively with considerable success.' Over the years, however, a number of complications have been noted with each type of replacement valve. Both types can be technically difficult to implant due to the bulk of the sewing ring. Also, residual flow gradients
M
remain because of altered blood flow patterns. The turbulence caused by this difference in the flow pattern can cause hemolysis of red blood cells. Patients have an increased risk of endocarditis following manufactured valve replacement. This risk is highest immediately after surgery and decreases to a constant, relatively low risk after six months. Homografts do not have this early increased risk but have a similar low, long-term risk for endocarditis. Patients who receive mechanical valves face a lifetime of anticoagulation that predisposes them to the risk of m a j o r h e m o r r h a g e . Anticoagulants also can cause birth defects or fatal hemorrhage in a fetus. They also pose a high risk of maternal and infant bleeding problems at delivery and can be transmitted to the
Patricia A. Wright, RN, CNOR, is organ procidrenient specialistlRN f i r s t assistant, Departmetit of Thoracic and Cardio\ascular Surgery. at the Uuii2ersity of Oklahoma Health Sciences Center, Oklahonia City. She earned her associate degree in iiiir.sing at the Uiiiveixity of Toledo (Ohio).
R o d C.Elkins, MD, is projessor and chief of Thoracic and Cardiovasculai~Si4i.gei.y at the University of Oklahoma Health Sciences Center, OkIahoma City. He earned his medical degree at the Unii9ersity of Oklahoma School of Medicine, Oklahoma City. 639
OCTOBER 1992. VOL 56. NO 4
AORN JOURNAL
Fig 1 . (Clnckuise fi-om upper left) bioprosthetic porcine valve, mechanical ball-in-cage valve, mechanical disc valve. composite mechanical disc valve with attached Dacron conduit.
nursing newborn. Mechanical valves can fail if one of the components breaks, or if the disc becomes fixed i n an open or closed position because of neointimal hyperplasia (ie, tissue growth on the valve). clot on the disc, or in surrounding structures (eg. the fabric-covered metal sewing ring. stems). Bioprosthetic valve durability also is a problem. These valves are predisposed to the formation of calcium deposits on the leaflets, especially in younger patients. These deposits render the valve stenotic, resulting in repeated valve replacement surgery. Each time a valve must be replaced. the procedure carries a higher mortality risk for the patient. In an effort to avoid the complications associated with mechanical and bioprosthetic valves and because cryopreservation techniques have improved. human heart valves (ie, homografts) are being used to replace valves in many patients.
Not everyone is a candidate for homograft valve replacement, however. T h e selection of a replacement valve depends on many individual patient factors (eg. age, replacement/failure risks, risks of life-long anticoagulation).
Pulmonaiy Autografts
A
pulmonary autograft procedure is complex c a r d i a c surgery in which a .patient’s d e f e c t i v e aortic v a l v e is replaced by moving his or her pulmonary valve to the aortic position and reconstructing the right ventricular outflow tract using a cryopreserved pulmonary homograft. Donald Ross, MB, Ch.B, FRCS, pioneered the pulmonary autograft procedure in Great Britain in 1967 as an alternative method of aortic valve replacement. Ross used an antibiotictreated cadaver pulmonary valve and conduit to
OCTOBER 1992, VOL 56, NO 4
replace the patient’s pulmonary valve and artery, which was moved to the aortic position.2 Cadaveric valves stored in antibiotic solution must be discarded after two months if not implanted. Development of cryopreservation techniques (ie, preservation of human tissue in dimethylsulfoxide by freezing at -196 “C in liquid nitrogen) made pulmonary autograft surgery more feasible by increasing the “shelf life” of homograft valves thus making more valves of different sizes available. The cryopreservation procedure also has decreased the risk of disease transmission because extensive tissue cultures and serologic testing are done on each valve, and careful attention is paid to antibiotic techniques in the preservation pr~cess.~ In the 25 years following Ross’ initial work, follow-up investigation reveals excellent longterm results for patients receiving these autografts. Ninety-six percent of these patients did not experience endocarditis, and 93% were spared aortic valve incompetence due to technical errors in the valve.4
Pulmonary Autograjl Indications
T
e primary indication for a pulmonary autograft is severe congenital aortic stenosis. Patients who are candidates for pulmonary autograft may experience aortic regurgitation or mixed aortic stenosidregurgitation. Other candidates for this procedure are patients who need to have their mechanical or bioprosthetic valves replaced, especially if they have a previous history of subacute bacterial endocarditis. For patients with a life expectancy greater than 20 years, pulmonary autograft, using homograft valve replacement for the pulmonary component, offers an effective alternative to mechanical or bioprosthetic valves.
Benefits
T
he use of a pulmonary autograft procedure has several advantages. The patient’s pulmonary valve can withstand the greater pressures exerted by the arterial side of the heart and it can function in a manner
AORN JOURNAL
similar to the aortic valve. In addition, the autograft is more streamlined and less bulky than alternative valves which are sutured into and surrounded by a fabric-covered metallic sewing ring. Moreover, the autograft valve provides the same turbulence-free blood flow pattern as a native healthy valve because it is one. Longterm, longitudinal studies over the past 25 years have shown excellent freedom from reoperation due to valve f a i l ~ r eThere . ~ is even documented echocardiographic evidence of autograft growth in children? If necessary, it is far less risky to replace a homograft valve and conduit in the right ventricular outflow tract than to use a replacement valve (ie, mechanical, bioprosthetic valve) on the left side of the heart. The autograft pulmonary valve, when moved into the aortic position, is less likely to need replacement because it is the patient’s own viable tissue. The homograft is used to replace the pulmonary valve in the right side of the heart with its lower pressures where, if necessary, it can be replaced more easily and without the added risk that a surgical procedure on the left ventricular outflow tract poses to the coronary arterie~.~ Another of the major benefits of the autografthomograft procedure is the freedom from the risks of life-long anticoagulant therapy that mechanical valve replacement requires. This is particularly important in children and young adults, women of child bearing age, and in patients who may be non-compliant with anticoagulant therapy. Patients with a history of subacute bacterial endocarditis have fewer episodes of this following valve replacement with autograft/homograft than those who have had replacement with mechanical or bioprosthetic valves.* Homografts also do not have to be blood-group matched because their fibroblastic tissue does not cause rejection phenomena. Autograft valve replacement also has been shown to be effective in patients of many ages. For example, at the University of Oklahoma Health Sciences Center, Oklahoma City, 90 patients, ranging in age from 1 week to 59 years, have successfully undergone the pulmonary autograft procedure. 641
OCTOBER IOQZ. VOL 56. NO 4
\ O R N . l O C RN41.
Risks
T
he autogr~ift/honiograftprocedure is technically riskier because performing a n autograft procedure involves a double valve replacement. Special techniques used i n the procedure also increase the risk of potential problems. For example. i n one of the autograft techniques the surgeon reimplants the coronary arteries into the pulmonary c o n d u i t . When these arteries a r e implanted. their alignment must be flawless to ensure that they are not kinked or twisted. which could cause coronary occlusion.’ Bleeding also is a major concerti because of the extensive suture lines required by the procedure. To prevent bleeding. the surgeon must pay fast i d i o 11s at t e ti t i o n to the an as t om0 se especially on the posterior side of the aorta and pulmonary artery. as well as the coronary reimplantation sites.
efore a pulnionar!- autograft procedure is scheduled. the patient undergoes a left and right heart catheterization. The surgeon uses data from this test and echocardiographic data to confirm the patient’s diagnosis of valvular disease. The surgeon elicits a complete history from the patient and performs a physical examination. He or she orders a posterior/anterior and lateral chest x-ray and electrocardiogram ( E C G ) to be performed. and asks laboratory personnel to perform the following tests on the patient: complete blood count (CBC). biochemistr! profile. prothrornbin time (PT). partial thromboplastin time (PTT). urinalysis. and a type and cross-match.
A M?
pulmonary autograft procedure usually i\ elective although i n some cases it may be urgent. If the surgery is not
extremely urgent. the patient and his or her family will meet with a primary cardiac intensive care unit (CICU) nurse for preoperative teaching. This client/care giver contact presents the patient and family with an opportunity to ask questions and verbalize concerns. It also sives the CICU nurse a chance to meet the patient and assess any needs particular to that patient. The nurse gives the patient and family a tour of the CICU and explains what will be involved in postoperative care. A checklist is used ( T a b l e 1 ) a n d this is kept with the patient‘s chart to ensure comprehensive teaching. The perioperative nurse focuses his or her assessment on gathering infomiation from the patient regarding allergies, past medical and surgical history, current medications. physical or mental deficits. and the patient’s level of understanding regarding the planned procedure (Table 3 ) . The perioperative nurse also performs a baseline physical assessment of the patient’s skin condition. circulation, mobility, and ability to communicate. The nurse assesses the patient‘s family or significant others for their understanding of the planned procedure, anxiety level. and coping mechanisms, and answers any questions they or the patient may have.
efore the patient arrives in the OR. the perioperative nursing team prepares the OR suite for a routine cardiac procedure. The nurses ensure that all necessary equipment (eg. electrocautery. a defibrillator, a c a r d i a c p a c e m a k e r a n d c a b l e s , a slush machine. a cardiopulmonary bypass machine) are in the room. Sterile instruments for this procedure are gathered and include a basic chest set and valve tray that includes cardiac retractors ( e g , atrial retractors, aortic valve retractors) cardiovascular needle holders, and mechanical and porcine valve annulus sizers. Sterile back table. Mayo stand, and patient drapes required for a cardiovascular procedure are gathered. Additionally. an inventory list of
OCTOBER 1997. VOL 56. NO 4
AORN JOURNAL
Table 1
Preoperative Baseline Physical Assessment Neurological Pupils Grips Coordination Speech ~
Level of Consciousness/Orientation
Cardiovascular Hypertension yes no Blood pressure Pulse Edema Jugular vein distention Peripheral vascular disease Bruits in carotid/femoral arteries ECHO data Heart cath data
Pulmonary Breath sounds Arterial blood gases: PHPCOZ PO? HCO, 0,Saturation ~
History of smoking Packs per dayUse of 0, at home Incentive spirometer mL
Musculoskeletal/Skin History of fractures Arthritis Facial fractures Skin ulcers
Renal Previous 24 hr intake output BUN Creatinine Last void: rnL History of dysuria yes Foley inserted: yes -no date time
time no
Gastrointestinal Bowel sounds Abdominal assessment Presence of bruits Last bowel movement
Pspchosocial Family present for preoperative teachingVerbalized understanding: Patient Family Education level: Patient Family Knowledge of illness Previous hospitalizations
Endocrine History of diabetes Last glucose Insulin AM/PM History of hepatitis Previous thyroid surgery
units
643
OCTOBER 1992, VOL 56.NO 4
AORN JOURNAL
Table 2
Preoperative Teaching Checklist Date CICU tour Explanation of postoperative care coughing/deep breathing splinting abdomen with pillow cardiac monitoring frequency of vital signs/nursing assessments equipment IV pumps 0 2 saturation monitors datascope arterial lines pressure monitor invasive lines pulmonary artery line endotracheal tube Foley che5t tubes wound sites chest exercise legs ankles incentive spirometry therapy turning lavage suctioning wound care explanation of alarms
Time
Nurse
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Fig 2. The pulmonary artery and valve are excised from the right ventricular outflow tract. (Figures 2 through 10 by M. LaWaun Hance, SA, PA-C)
the pulmonary homografts that are available in the nitrogen freezer is posted in the room for later reference. The surgeon will refer to this list when choosing the appropriately sized homograft. Once the flat surfaces and lights are damp dusted, packs and instrument trays are arranged in the room and opened. The nurse places a temperature regulating mattress on the OR bed, sets the temperature at 37 "C (98.6 OF), and covers the mattress with a bath blanket and lifting sheet. The bath blanket protects the patient from direct contact with the temperature regulating mattress and the lifting sheet allows the surgical team to move the patient more easily. The perioperative nurse also checks on the availability of blood and blood products that have been ordered preoperatively and helps anesthesia personnel obtain the necessary anesthetic drugs and equipment, When possible, needle, sponge, and instrument counts are completed before the patient is brought into the
room to ensure a quiet atmosphere.
Preoperative Patient Care
T
he perioperative nurse meets the patient and his or her family in the preanesthetic holding area. After confirming the patient's identification, assessing his or her condition, checking the chart for a signed consent form for the appropriate operative procedure, and the presence of ordered laboratory reports, the nurse transports the patient to the OR suite. The nurse helps the patient transfer from the cart to a supine position on the OR bed, and makes him or her comfortable with warm blankets. A safety belt is placed across the knees. Pediatric patients may be held on the anesthesiologist's lap for induction if he or she feels it would make the child less frightened and more cooperative. The nurse helps the anesthesia team to 645
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Fig 3. The aorta is cross clamped, cardioplegiasolution given, and the aortic valve is removed.
Fig 4. The pulmonary artery and valve are lowered into the aortic annulus.
induce and intubate the patient, and to insert IVs, a radial arterial line and a pulmonary artery (ie, Swan-Ganz) catheter cordis. A cordis is the port inserted into the internal jugular vein through which fluids can be given intraoperatively or through which a pulmonary artery catheter can be inserted in the CICU. A pulmonary artery catheter is not inserted preoperatively because it would interfere with removal of the pulmonary valve and artery, and anastomosis of the pulmonary homograft. A doublelumen catheter monitoring line may be used in a child. In adults, these lines may be inserted in the preanesthetic holding area; in children, they are inserted after induction. The perioperative nurse inserts a Foley catheter that contains a special temperature monitoring probe. This cathetedprobe monitors the patient’s urine output as well as core temperature during the procedure. A regular Foley may be used in combination with a rectal temperature probe if a catheter with a temperature probe is not available. With the patient in a
supine position, the nurse pads all bony prominences with foam “egg crate” material, tucks the patient’s arms to his or her side using the lifting sheet to secure the patient’s arms without occluding arterial and venous lines. The nurse places an electrosurgical unit dispersive pad on the patient’s buttocks or anterior thigh. A cage type tray, similar to an ether screen but with a tray across the top, is positioned over the patient’s face to prevent drapes and surgical personnel from contacting the patient’s face.
Surgical Procedure
A
fter satisfactory induction via general anesthesia, the nurse preps the patient from chin to knees, and from side-toside to the mid-axillary line, with alcohol. The surgical team drapes the patient with sterile towels and an iodine-impregnated adhesive wound drape. This is covered by a sternotomy sheet. The surgeon carries the incision down to the sternum and after performing a median ster647
AORN JOURNAL
OCTOBER 1992, VOL 56, NO 4
Fig 5 . An aortic punch is used to make two button-shaped holes in the pulmonary conduit.
Fig 6. The periphery of the button-shaped holes is sutured around the coronary ostia, and the distal suture line between the pulmonary conduit and the aorta is completed. 648
OCTOHEK 1992. VOL 56. NO 4
notomy, he or she opens the pericardium and uses pericardial stay sutures to maintain access and a clear view of the heart. The surgeon places a double purse string suture in the ascending aorta and two separate purse string sutures in the right atrium. The anesthesiologist heparinizes the patient and the surgeon cannulates the aorta. He or she then cannulates the superior and inferior vena cavae through the right atrium and the perfusionist begins cardiopulmonary bypass. With the patient on bypass, the perfusionist begins the cooling process, and the temperature regulating blanket is set to cool the patient. Routinely, patients are cooled to 22 "C (71.6 O F ) . The surgcon inserts a left ventricular vent through the right superior pulmonary vein to aid in decompression of the heart and to cnhancc the ability to see once the aorta is opened. In an adult, the aorta is cross-clamped and the surgeon administers approximately 1000 mL of oxygenated, cold blood cardioplegia solution through the aortic root to arrest the heart. Less cardioplegia is used in a child. Occasionally it is necessary, due to aortic insufficiency, to give retrograde cardioplegia solution through a cannula inserted via a right atriotomy into the coronary sinus. Aortic valve insufficiency prevents the valve from closing normally and allows cardioplegia solution to flow into the left ventricle rather than into the coronary system. This would not properly cool the entire heart, thus retrograde cardioplegia is used. T o maintain myocardial temperature below 12 "C (53.6 O F ) , additional cardioplegia solution is given every 30 minutes either retrograde or directly into the coronary ostias and the heart is packed in saline slush. The surgeon places an insulation pad between the heart and the pericardial sac to prevent phrenic nerve damage from the cold slush. A myocardial temperature probe is inserted into the myocardium to monitor heart temperature during cold arrest time. An aortotomy is performed distal to the aortic valve, and the surgeon inspects and removes the valve. He or she then opens the pulmonary artery at the takeoff of the right pulmonary
AORN JOLKNAL
artery and inspects the pulmonary valve. Once the surgeon determines that the pulmonic valve is normal, he or she enucleates the valve and artery from the right ventricular outflow tract. Extreme care is taken to protect the left coronary artery and the first septa1 branch of the left anterior descending artery during removal of the pulmonary conduit and valve because of their proximity to the dissection line. During autograft/homograft procedures the perioperative nurse maintains the operative records, helps anesthesia personnel monitor patient urine output, blood loss, temperature, and cardiac rhythm.
Autograft Techniques
A
t this point in the procedure, the surgeon can use one of two autograft tech.niques depending on the pathology presented by the patient.'O The intra-aortic implant technique. With this technique, the surgeon removes the aortic valve (Figs 2, 3, and 4), trims the pulmonic valve and conduit, and sutures it into the annulus of the aortic valve. He or she uses an aortic punch to make two button-shaped holes in the pulmonary artery (Fig 5). The surgeon then sutures the periphery of the two button-shaped holes around each coronary ostia (Fig 6). The aortotomy is then closed, completely enclosing the pulmonary autograft inside the aorta (Fig 7). The intra-aortic technique is the procedure of choice when possible. The root replacement technique. Using this technique, the surgeon removes the coronary artery ostia from the aorta with a buttonshaped portion of aortic wall (Fig 8). The aorta is opened at least one cm distal to the right coronary artery in a transverse manner. He or she sutures the pulmonary valve and artery onto the top of the left ventricle, situating the autograft so that the left coronary ostia is centered in one of the pulmonary valve sinuses. The surgeon makes a hole in the pulmonary artery (Fig 9) using an aortic punch and reimplants the left coronary artery button into the button hole with a running
cr 649
AORN JOURNAL
OCTOBER 1992, VOL 56, NO 4
Fig 7. The final result showing the over sewn aortic cannulation site, closed aortotomy, and interposed pulmonary homograft.
Fig 8. The coronary ostia are removed from the aorta on a button-shaped portion of aortic wall. 652
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Fig 9. The pulmonary valve and artery are sutured onto the top of the left ventricle. An aortic punch is used to make two button holes in the pulmonary conduit. The coronary ostia buttons are sutured into the button holes.
Fig 10. The completed root replacement showing the patient’s pulmonary artery in the aortic position and the pulmonary homograft replacing the native pulmonary artery. 653
OCTOBER 1992, VOL 56. NO 4
AORN JOURNAL
Fig 11.The pulmonary homograft after removal from the nitrogen freezer and thawing. suture. He or she completes the distal suture line between the pulmonary artery and the ascending aorta (Fig 10). After distending the aorta with cardioplegia solution to identify the proper location to implant the right coronary artery, the surgeon reimplants the right coronary button as the left was done. Root replacement has been the procedure of choice in patients with a small aortic annulus, a dysplastic annulus and significant subvalvular stenosis, significant abnormalities involving one or more of the coronary sinuses, o r in patients with coronary ostia that a r e 180 degrees opposed. Polypropylene suture is used for suture lines on the pulmonary autograft and pulmonary homograft anastomoses in adults. In children, absorbable 5-0 polydioxanone suture material is used to allow for growth of the pulmonary autograft, and polypropylene suture is used on the pulmonary homograft anastomoses. 654
Pulmonary Homograft Anastomoses
w
en the autograft has been completed, the surgeon removes the aortic cross clamp. He or she checks the aortic suture lines and the appropriately sized pulmonary homograft (ie. similar in size to the aortic annulus), which has been selected during the pulmonary autograft anastomosis, is thawed. When the surgeon chooses a pulmonary homograft from the posted inventory list, the nurse removes the homograft from its slot in the nitrogen freezer. He or she wears insulated gloves to protect the skin against severe burns that can be caused by contact with either the packaged homografts or the liquid nitrogen in the freezer. The nurse keeps the homograft package at room temperature for five minutes and then immerses the triple-wrapped package in a 3L,
OCTOBER 1992, VOL 56, NO 4
42 "C (107.6 O F ) , water bath until the solution in which the homograft is packed turns to slush (eg, 15 to 20 min). The circulating nurse monitors this thawing process, and when the homograft is ready to be transferred to the sterile field, he or she opens the two outer plastic wraps. The scrub nurse removes the inner sterile package, cuts open the top, and places the homograft into 1 L of room temperature 5% Dextrose and lactated Ringer's solution for its final rinse. He or she gently agitates the homograft in this solution for five minutes. When thawed and rinsed, the surgeon cuts a small tissue sample from the homograft to be sent for culture and sensitivity and carefully examines the homograft to be sure the valve is competent and the conduit is of good quality (Fig 11). The surgeon inspects the myocardium in the area of the excised pulmonary homograft for bleeding vessels and obtains hemostasis. He or she then trims the homograft and sutures the proximal end onto the right ventricular outflow tract, taking special care with the region of the first septa1 perforating artery. The distal end is sutured to the native pulmonary artery with a running suture. During the pulmonary homograft anastomoses, the perfusionist initiates rewarming of the patient. This is accomplished by warming the blood in the cardiopulmonary bypass circuit as it is returned to the patient and by setting the temperature regulating mattress to 37 "C (98.6 OF).
Upon completion of the anastomoses, the surgeon evacuates air from the apex of the heart with a needle. He or she removes the cardioplegia cannula and over sews the insertion site. Once the patient reaches 37 "C (98.6 O F ) , bypass is discontinued, the surgeon decannulates the patient, and the anesthesiologist administers protamine sulfate to reverse the effects of heparinization. The surgeon inspects all suture lines and obtains hemostasis. If the patient's heart does not revert to sinus rhythm, defibrillation may be necessary once the patient is rewarmed. The surgeon may place temporary epicardial pacing wires if there is a problem with the patient's heart rhythm. When
AORN JOURNAL
the patient is hernodynamically stable, an intraoperative echocardiogram can be used to verify autograft function. The surgeon inserts one or two mediastinal/pleural chest tubes and the scrub nurse connects them to a chest drainage system that is attached to 20 cm Hg suction. The surgical team closes the sternum with wire suture followed by routine closure of subcutaneous tissues and skin. The circulating nurse telephones a report to the CICU primary nurse approximately onehalf hour before the patient is scheduled for transport. This alerts the CICU nurse of the patient's condition and the need for additional patient monitoring equipment. After skin closure, the perioperative nurse assists the scrub nurse with dressing the patient's wound and preparing the patient for transport to the CICU. The nurse covers the patient with warm blankets and helps the anesthesiologist and surgical team to move the intubated patient to an ICU bed for transport to the CICU. The nurse assists anesthesia personnel in transporting the patient to the CICU. On arrival in the CICU, the perioperative nurse gives report to the CICU primary nurse.
Postoperative Care
W
hen the patient is admitted to the CICU, the immediate goal is to maintain or stabilize the patient's vital signs and prevent postoperative complications such as hemorrhage or hypotension. The surgeon may insert a pulmonary artery catheter to monitor an unstable patient, although this is not routine. If the patient remains stable, the anesthesiologist or CICU medical staff remove the patient's endotracheal tube the morning following surgery, and on the second postoperative day, the patient is transferred to the surgical ward. The surgeon uses a postoperative echocardiogram, done within 10 days of the procedure, to evaluate valve function. In a patient who experiences no complications, the hospital stay averages seven days. The surgeon discharges the patient with post655
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
surgical instructions for a gradual return to normal activities of daily living. Heavy lifting is prohibited for six weeks. The patient is asked to return for a follow-up visit to the clinic o n e week after discharge with instructions to have a P A a n d lateral c h e s t x - r a y a n d EKG d o n e before the clinic appointment. Patients are seen a g a i n in o n e m o n t h . E c h o c a r d i o g r a m s a r e scheduled at three and six months in conjunction with clinic visits and then yearly.
Summury
I
n selected patients, the pulmonary autograft procedure utilizing cryopreserved h o m o grafts for reconstruction of the right ventricular outflow tract is becoming an increasingly popular aortic valve replacement alternative. Longitudinal statistical reports s h o w that patients need reoperation less often with this procedure. Because the valve is autogenous tissue, all indications to date show that the valve continues to function for extended periods of t i m e in a l l p a t i e n t s a n d can a c c o m m o d a t e growth in children. At the same time, transfer of the pulmonary valve to the aortic position provides a natural valvular flow pattern a n d freedom from the degenerative changes associated with bioprosthetic valves or the need for anticoagulation associated with mechanical valves. Notes 1. D Graf, L Gonzalez-Lavin, “The homograft: A new dimension for cardiac valve replacement.” AORN Journal 48 (November 1988) 911-917; P Stelzer, R C Elkins. “Homograft valves and conduits: Applications in cardiac surgery.” Cui-renr Problems in Surgery 26 (June 1989) 381-452. 2. D Ross. “Replacement of the aortic valve with a pulmonary autograft: The “switch” operation.” Anrials of Thorucic, Surgery 52 (December 1991) 1346-1350. 3. M O’Brien et al. “The cryopreserved allograft aortic valve,“ Journal of Cardiac Surgery 1 (March 1987) 153-167. 4. R C Elkins et al. “Pulmonary autograft replacement in children: The ideal solution?” Unpublished manuscript, presented at the American Surgical Association annual meeting, Palm Desert CA, April 4-8. 1992. 656
5. A Robles et al, “Long-term assessment of aortic valve replacement with autologous pulmonary valve,” Annals of Thoracic Surgery 39 (March 1985) 238-242; D Ross, “Pulmonary valve autotransplantation (the Ross operation),” Journal of Cardiac Surgery 3 suppl (September 1988) 313-319. 6. H Murata, “A study of autologous pulmonary valve replantation,” Nippnn Kyobu Ceka Gakkai Zasshi 32 (February 1984) 144.153. 7. G Gerosa, R McKay, J Davies, D N Ross, “Comparison of the aortic homograft and the pulmonary autograft for aortic valve or root replacement in children,” Journal of Thoracic Cardiovascular Surgery 102 (July 1991) 51-61. 8. J K Kirklin, A D Pacifico, J W Kirklin, ”Surgical treatment of prosthetic valve endocarditis with homograft aortic valve replacement,” Journal of Cardiac Surgery 4 (December 1989) 340-347; C Yankah, R Hetzer, “Valve selection and choice in surgery of endocarditis,” Jour-naf of Cardiac Surgery 4 (December 1989) 324-330; J K Lau et al, “Surgical treatment of prosthetic endocarditis: Aortic root replacement using a homograft,” Journal of Thoracic Cardioiiascular Surgery 87 (May 1984) 7 12-716. 9. R A Hopkins, J St Louis, P Corcoran, “Ross’ first homograft replacement of the aortic valve,” Annals o f Thoracic S u r g e r y 52 (November 1991)1190-1193. 10. R C Elkins et al, “Pulmonary autograft replacement of the aortic valve: An evolution of technique,” Journal of Curdiac Surgery 7 (June 1992) 108-116; D Ross, “Technique of aortic valve replacement with a homograft: Orthotopic replacement.” Annals of Thoracic Surgery 52 (July 1991) 154-156.
OCTOBER 1992. VOL 56, NO 4
4 0 R N JOL RNAL
hxamination PULMONARY AUTOGRAFT
1.
2.
3.
4.
5.
6.
658
Two primary categories of manufactured valves have evolved to replace defective heart valves. What are they? a. extruded plastic and Dacron b. mechanical and bioprosthetic c. ring and leaflet d. residual flow and gradient Manufactured valves can be technically difficult to implant because a. The sewing ring is too small. b. The sewing ring is too bulky. c. The sewing ring is easily damaged. d. There is no sewing ring. Patients who receive mechanical valves face a lifetime of and risk major a. surgery: bankruptcy b. anticoagulation; hemorrhage c. antimicrobial therapy; drug reactions d. immunosuppressive therapy; organ rejection Bioprosthetic valves are predisposed to on the leaflets which make the valve a. neointimal hyperplasia; dysfunction b. fat deposits: remain open c. calcium deposits; stenotic d. potassium deposits: remain open Manufactured valves create residual flow gradients. This turbulence causes what? a. audible bruits in the chest b. neointimal hyperplasia c. hemolysis of red blood cells d. high patient mortality Pulmonary autograft procedures (PAPs) are done to reconstruct the patient’s a. defective aortic valve
b. left ventricular outflow tract c. right ventricular ouflow tract d. defective pulmonary valve 7. Pulmonary autograft procedures are indicated for patients with 1. severe congenital aortic stenosis 2 . aortic stenosis and/or regurgitation 3. hypoplastic left hearts, 4. manufactured valves and a history of subacute bacterial endocarditis a. 1 and 4 b. 2 a n d 3 c. 1, 2, and 4 d. 2 , 3, and 4 Patients with a life expectancy of greater 8. than 20 years are good candidates for a bioprosthetic valve. a. true b. false 9. Studies have shown that patients with homograft procedures have less and a. rejection phenomena: bleeding b. aortic valve incompetence; bleeding c. endocarditis; aortic valve incompetence d. infection; pulmonary valve incompetence 10. Patients with mechanical or bioprosthetic valves who have histories of subacute bacterial endocarditis are good candidates for PAPs. a. true b. false 11. W h y i s a P A P considered technically riskier? 1. It involves tissue from another person, and thus there is the risk of rejection.
OCTOBER 1992, VOL 56, NO 4
2. It takes longer, which results in increased anesthesia time and its associated risks. 3. The procedure involves a double valve replacement. 4. In one version of the PAP, the surgeon must reimplant the coronary arteries and can cause occlusion of them if he or she does this improperly. a. 1 and2 b. 2 a n d 3 c. 3 and 4 d. 2 a n d 4 12. Because the surgeon is working with the aorta and pulmonary artery, is a major concern. a. cardiac blood flow b. bleeding c. heparinization d. cardiopulmonary bypass 13. One advantage to the use of a pulmonary homograft over a mechanical or bioprosthetic valve is that the patient does not need a. surgery b. intraoperative heparinization c. postoperative anitcoagulation d. intraoperative cardiac bypass 14. The need for valve replacement is a problem with mechanical or bioprosthetic valves. Why are autografts/homografts better in this regard? 1. The homograft used to replace the pulmonary valve can be replaced more easily without the added risk that surgery on the left ventricular outflow tract poses to the coronary arteries. 2. Cadaver valves are easy to come by and do not need replacement. 3. The autograft pulmonary valve, when moved into the aortic position, is less likely to need replacement because it is the patient’s own viable tissue. 4. Only one valve is replaced, thereby reducing the number of valves that might need replacement in the future. a. 1 and 2 b. 2 a n d 3
AORN JOURNAL
c. 1 and 3 d. 2 a n d 4 15. Homografts do not need to be blood-group matched. Why? a. They can be replaced easily if rejected by the patient. b. Fibroblastic tissue does not cause rejection phenomena. c. Fibroblastic tissue cannot be bloodgroup matched. d. Homografts are the patient’s own tissue. 16. Pulmonary autograft procedures have been performed on patients who range in age from one week to 95 years. a. true b. false 17. The benefit of moving the patient’s pulmonary valve into the aortic position is 1. It functions in a manner similar to the aortic valve. 2. It is the only way to replace the aortic valve. 3. It can withstand the greater pressures exerted by the arterial side of the heart. 4. It takes less surgical time to do this. a. 1 and 2 b. 2 a n d 3 c. 1 and3 d. 2 a n d 4 18. Autografts are than manufactured valves and provide the same pattern as a healthy native valve. a. less expensive; electrocardiogram b. less bulky, turbulence-free blood flow c. more bulky; performance d. easier to sew; hemolysis 19. Long-term follow-up on pulmonary autograft patients shows less valve failure and need for reoperation. a. true b. false 20. Autografts have been documented to show in children a. problems b. growth c. retardation d. clotting problems 659
OCTOBER 1992, VOL 56, NO 4
21. Because bleeding is a concern with PAPS, what would be important for the perioperative nurse to assess? a. PT, PTT laboratory results b. history of anticoagulant therapy c. skin condition, presence of bruising d. all of the above 22. A PAP requires cardiac bypass cooling. What patient care should the nurse perform? 1. Protect patient's skin from temperature regulating mattress by using a bath blanket. 2. Insert a catheter that contains a temperature probe, or a standard rectal temperature probe. 3. Cover the patient with ice. 4. Ensure that sterile slush is available. a. 1 and 3 b. 1,2, and 3 c. 1,2, and4 d. 2 and 4 23. When removing the size homograft chosen by the surgeon from the nitrogen freezer what must the circulating nurse do? a. Wear insulated gloves to protect himself or herself from severe bums. b. Keep the homograft at room temperature for five minutes. c. Immerse the homograft in a 42 "C water bath for 15 to 20 minutes. d. all of the above 24. When the perfusionist warms the patient, what should the nurse be aware of? a. the possibility of malignant hyperthermia b. the possibility of convulsions c. the possibility of fibrillation d. the possibility of bums from the temperature regulating mattress 25. If the patient does not revert to sinus rhythm, what may be necessary? 1. defibrillation 2. heart transplant 3. temporary epicardial pacing 4. permanent cardiac pacing a. 1 and 3 b. 2 only
AORN JOURNAL
c. 2 and 4 d. 4 only Professional nurses are invited to submit clinical or managerial manuscripts for the home study program. Manuscripts or queries should be sent to the Clinical Editor, AORN Journal, 10170 E Mississippi Ave, Denver, CO 80231. As with all manuscripts sent to the Journal, papers submitted for the home study program should not have been previously published or submitted simultaneously to any other publication.
Student Nurses Join National League The National League for Nursing (NLN) has formed a partnership with the National Student Nurses Association (NSNA) and is offering student nurses the chance to join NLN for $30. The membership fee includes access to the new NLN Center for Career Advancement, discounts on NLN books, special rates on professional development programs, and a oneyear subscription to NLN's journal, according to a June 1992 NSNA press release. The special rate is valid until one year after graduation; however, proof of NSNA membership is required for the discount. The release states that NSNA members who join the NLN will receive all membership benefits except voting and office-holding privileges.
661
OCTOBER 1992, VOL 56, NO 4
AORN JOURNAL
Answer Sheet PULMONARY
P
lease fill out the application and answer form below and the evaluation on the back of this page. Tear out the page from the Journal or make photocopies and mail to: AORN Accounting Department c/o Home Study Program 10170 E Mississippi Ave Denver, CO 80231 Event # 935004
AUTOGRAFT
Mark only one answer per question
1 2 3 4
Session ## 5521
Program offered Oct 1, 1992
5
The deadline for this program is April 30, 1993.
6
1. Record your identification number in the appropriate section below. 2. Completely darken the space that indicates your answer to the examination starting with question one. 3. A score of 70% correct is required for credit. 4. Record the time required to complete the program 5. Enclose fee: Members $7; Nonmembers $14.
7 8
9 10 11
12
AORN (ID) # If nonmember, please provide Social Security
13
#
14
Name
15
Address
16
City
17
State
Zip
18
RN license and state
19
Florida license #
