The Inferior Vena Cava U m b r e l l a Filter Kazi Mobin-Uddin, Joe R. Utley, and Lester R, Bryant
HROMBOEMBOLIC DISEASE is a major cause of morbidity and mortality in hospitalized patients. Pulmonary embolism is one of the most common lethal processes found at autopsy. It has been estimated that approximately 570,000 patients suffer nonfatal pulmonary embolism and 140,000 patients suffer fatal pulmonary embolism in the United States each year. Barker and associates 2 have reported on the natural course of untreated thromboembolism in postoperative patients. Of 1655 patients with pulmonary embolism, the first episode was fatal in 24.4%, and death occurred in 18.3% of the nearly one-third who had recurrent embolism. Despite anticoagulant therapy that has been considered adequate, recurrences of pulmonary embolism are not uncommon. Interruption of the inferior vena cava (IVC), by either ligation or plication, has offered good protection against recurrent embolism with the risk of a major surgical procedure and anesthesia. The operative mortality rate in patients with significant cardiopulmonary disease has been high a-s depending upon the severity of the underlying disease and the extent of obstruction to pulmonary blood flow. To avoid general anesthesia and a major surgical operation, a simple transvenous catheter technique was developed for interruption of the IVC with an intracaval device of an umbrella design. 6-~~ After satisfactory studies in dogs and an assessment of clinical results in the first t00 patients, the umbrella filter* (UF) was released for general clinical use in January 1970. The present report includes the results of clinical filter implants in 2215 patients as reported by the evaluating physicians.
T
MATERIALS AND METHODS The intracaval filter (Fig. 1) is of an umbrella design and consists of six spokes of stainless steel alloy1" radiating from a central hub. A thin sheet of silasticr covers
From the Department of Surgery, Division o f Cardiothoracic Surgery, University of Kentucky Medical Center, Lexington, Ky. Reprint requests should be addressed to Kazi MobinUddin, M.B., B.S., Section o f Cardiovascular Surgery, Fredric C. Smith Clinic, 1040 Delaware Avenue, Marion, Ohio, 43302. 9 1975 by Grune & Stratton, Inc.
the metal on each side, but the spokes extend 2 mm beyond the silastic "body". There is a 1-mm threaded hole in the center. There are 18 fenestrations in the silastic body, each with a diameter of 3 ram. The threaded hole in the center provides fixation to the styler for implantation. The original caval umbrella was 23 mm in diameter, but episodes of filter migration led to development of the 28-mm device. By virtue of its spring action, the large filter will adjust to all sizes of the IVC in adults. The catheter used for implantation of the umbrella consists of a No. 7 cardiac catheter with a metal capsule at the end. The capsule has a diameter of 7 mm and a length of 32 mm. A threaded stylet fits inside the catheter and capsule for control of the filter. The UF is threaded onto the end of the styler and is unscrewed one-half turn (Fig. 2). Using a swab, the umbrella and the inner surface of the loading cone are lubricated with a sterile, water soluble lubricant (Lubrifax, K.Y. Jelly, or Glyserine) mixed with a few milliliters of heparin. The UF i s pushed all the way into the distal portion of the loading cone and the applicator-capsule is advanced firmly into the loading cone. An assistant is particularly useful in holding rite applicator capsule inside the loading cone. While maintaining the axial alignment, the stylet, with the help of a pinwise, is pulled back through the applicator, thus loading the UF into the capsule. The pin wise is advanced onto the luerlok hub of the applicator and retightened to prevent the umbrella filter from being accidentally ejected from the capsule or unscrewed from the stylet while manipulating the catheter.
Umbrella Filter Implantation Under local infiltration anesthesia, a small incision is made at rite right base of rite neck and rite right internal jugular vein is isolated between the two heads of the sternocleidomastoid muscle. A vascular clamp is applied proximally to occlude the vein and an umbilical tape tourniquet is put in place for distal control. The vascular clamp and tourniquet are very important for the prevention of air embolism and bleeding. The applicator-capsule containing the collapsed UF is inserted via a venotomy in the internal jugular vein (Fig. 3) and advanced under fiuroscopic control through the superior vena cava and right atrium in the IVC. The applicator is generally advanced to the level of the bifurcation of the 1VC and it is then withdrawn so that the distal tip of the capsule is positioned at the level of the midpoint of the third lumbar vertebra. The pin wise is loosened, moved 2 cm proximally, and then retightened. After rechecking the position of the distal capsule under fluorscopy, the styler is advanced by pushing on the pin wise and the filter is ejected from the *Edwards Laboratories, Santa Ana, Calif. t Elgiloy Company, Elgin, IlL Dow Coming Corporation, Midland, Mich.
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clamp is placed on the vein distally, and the vessel is repaired before wound closure.
TECHN ICAL CONSIDERATIONS
Fig. 1. (A) To the right is the 28-mm filter now recommended for use in all adult patients. The 23-mm filter may have application in patients less than 125 pounds. (B) Catheter used for umbrella filter implantation.
capsule. The filter should spring open and lightly fix in place at the intervertebral disc between the third and fourth lumbar vertebra. The pin wise is moved 2 cm proximal to the luerlok hub and retightened. Slight, but finn upward traction is applied several times on the stylet to securely fix the filter into place. Slight upward traction is maintained while the stylet is unscrewed from the filter. The applicator is withdrawn from the vein, a vascular
The following operative details are emphasized: (1) Special care should be exercised in dissecting the adherent posterior wall of the internal juglar vein. The clavicular head of the sternocleidomastoid muscle may be divided to improve exposure. (2) The venotomy should be kept closed except during the actual insertion of the applicator capsule to avoid air embolism. (3) Occasionally, difficulty is experienced in advancing the applicator-capsule from the juglar vein into the superior vena cava. It usually hangs up in the vein under the clavicle. The following measures may prove helpful: handle the vein as little as possible to prevent spasm; allow the umbrella to protrude slightly at the end of the capsule to form a "bullet nose"; pass a suitable size Hagar dilator via the venotomy site and note the direction of opening into the superior vena cava; insert the applicator-capsule half-way into the vein, release the distal tape and apply slight counter-traction with the proximal tape, before advancing the applicator in the direction previously noted; do not use force to advance the applicator. Slight lubrication of the applicator-capsule may be helpful. (4) At times the applicator may not pass from the right atrium into the IVC, or it may pass preferentially into the right renal or hepatic vein. Under these circumstances, the applicator is withdrawn into the neck and a slight gentle bend is made in the applicator catheter, just proximal to the capsule. The applicator can then be maneuvered by rotating it past the obstruction. Rarely,
Fig. 2, Demonstrates the technique of loading the umbrella filter into the applicator-capsule,
INFERIOR VENA CAVA UMBRELLA FILTER
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Fig, 3. (A) The applicator-capsule containing the collapsed umbrella filter has been inserted via the right internal jugular vein into the inferior vena cava below the renal veins. (BJ The filter has been ejected from the capsule into the inferior vena cava. (C) The stylet has been unscrewed from the filter and the applicator has been withdrawn,
because of a prominent eustachian valve, the applicator-capsule cannot be advanced from the right atrium into the IVC. Under such circumstances, a guide wire is inserted via the jugular vein into the IVC. After turning the patient to one side, the applicator can then be easily manipulated into the IVC. (5) An inferior venacavogram made before umbrella insertion is a very valuable adjunct. It demonstrates the level of the renal veins and the size of the IVC, and it may reveal any unsuspected anatomical abnormalities of the IVC n-12 or the renal veins, x3 Any thrombus in the IVC that may interfere with placement of the UF can also be detected. (6) Accidental placement of the UF in the IVC above the renal veins can be corrected by displacing the filter downward by the applicator-capsule to a level below the renal veins. POSTOPERATIVE MANAGEMENT
Following UF implantation, anticoagulant therapy is withheld for 12 hr to minimize the possibility of retroperitoneal bleeding. Thereafter, intravenous heparin is resumed for 7-10 days, preferably
by continuous infusion to maintain the partial thromboplastin time or the Lee-White clotting time at two times the control value, Oral anticoagulation with Warfarin sodium is started on the 3rd postoperative day and continued for 3 mo. Patients with continued predisposing factors such as cardiac failure and those with chronic obstructive airway disease associated with microemboli and cor pulmonale receive long-term anticoagulants after UF insertion. Elevation, elastic support, and early ambulation are employed to prevent or control peripheral edema. SELECTION OF PATIENTS FOR U M B R E L L A PROCEDURE
Initially IVC interruption with the UF was used only in poor risk patients for whom surgical ligation or plication would have carried a higher operative risk. A large number of physicians who have gained experience with the umbrella procedure are now using it as the method of choice. The UF has been used in patients who have recurrent pulmonary embolism despite adequate
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MOBIN-UDDIN, UTLEY, A N D B R Y A N T Table 1. Summary of Clinical Results in Patients Treated with the Umbrella-Filter as of November 1973 No. of Patients
F liter I mplants Proximal filter migration Distal filter migration* Filter dislodgement without migration Misplacement of filter Right renal vein Right lilac vein Recurrent emboli Fatal Nonfatal Clinical edema Phlebitis
23 mrn Filter 1,981
28 mm Filter 234
Total No. of Patients 2,21 5
20 6 20
2 0 0
22%-0.9% 6%-0,27% 20%-0.9%
7 20
0 0
7%-0.3% 20%-0.9%
18 47 102 33
0 6 13 2
18%-0.8% 53%-2.3% 115%-5.1% 35%-1.5%
*Following closed cardiac massage.
anticoagulation therapy, in those for whom anticoagulants are contraindicated, in patients with pulmonary embolism and shock, 14 and following pulmonary embolectomy, is Prophylactic caval interruption with the UF has been used in high risk patients with recent deep venous thrombosis while awaiting a surgical procedure, in those with iliofemoral thrombosis that has not responded to medical management and in a controlled study group before hip nailing. 16
Results The results are summarized in Table 1. In 71 patients the UF could not be implanted mainly because of the inability to insert the applicatorcapsule via the right internal jugular vein. In five of these patients, the left internal jugular vein and in one the right common femoral vein, was used to implant the UF.
Mortality and Recurrent Embolism Of the 2215 patients in whom the UF was implanted, recurrent embolism has been reported in 3.0% (fatal, 0.8%). For three patients, blood clot from the proximal surface of the UF was implicated as the source of recurrent pulmonary emboli. FILTER MIGRATION
The clinical data of patients in whom filter migration occurred is summarized in Table 2. Filter migration has occurred in two of the 234 patients who have received the larger 28-mm filter. Of the 1981 patients in whom a 23-mm filter was used, proximal migration occurred in 20 instances.
The filter lodged in a main branch of the pulmonary artery in 13 patients, in the right ventricle in two, in right atrium in four, and in the IVC above the renal veins in three patients. Distal migration of the UF into the right iliac vein following closed cardiac massage has been reported in six patients.
Filter Dislodgement Without Migration Partial dislodgement of the UF without migration has been reported in 20 patients. To prevent migration, the larger 28-ram filter was implanted just above the previous filter in six patients. In the remaining patients, either nothing was done or Table 2. Clinical Data on Patients with Umbrella-Filter Dislodgement and Proximal Migration No. of Patients 13
Filter Migrated To:
Pulmonary artery 3 Fatal-embolized with massive thrombus 7 R e m o v e d - t w o died postoperatively 3 Left in place1 died few days later and 2 died after 3 months, death unrelated. Right ventricle 1 Removed on cardiopulmonary bypass 1 Died 6 days later, no autopsy Right atrium 1 Fatal-embolized along with massive thrombus 1 Found at autopsy, death unrelated 2 Removed, 1 died postoperatively Suprarenal inferior vena cava 1 Died of cancer at 6 wk 1 Died of myocardial infarction 1 yr later 1 Alive and well. Venogram showed patency of I VC.
INFERIOR VENA CAVA UMBRELLA FILTER
surgical interruption of the IVC was performed with or without removal of the filter.
Misplacement of the Filter The UF has been improperly placed in the suprarenal IVC, the right renal vein and the right iliac vein. In three patients in whom the UF was accidentally extruded into the suprarenal IVC, the filters could be pushed downward with the applicator-capsule into the IVC below the renal veins. In two of these patients, a second filter was implanted proximal to the first because the latter became tilted as it was moved downward by the applicator-capsule. Of the seven patients in whom the UF was inadvertently misplaced in the right renal vein, in three, the UF has been removed and IVC interrupted by direct surgical approach. The UF was mistakenly placed in the right iliac vein in 20 patients. These have been treated either by removing the filter with interruption of the IVC or by implanting an additional filter in the IVC. In one patient, the applicator-capsule accidentally perforated the hepatic vein and the umbrella was extruded into the retroperitoneal space. Significant retroperitoneal hematoma has been reported in five patients, right recurrent laryngeal nerve injury in two, and perforation of duodenum and ureter in one patient each. Air embolism during filter insertion has occurred in two patients, (fatal in one). Acute renal failure developed postoperatively in two patients in whom the UF was placed just below the renal veins. Exploratory laparotomy in one patient revealed an impingement on the blood flow from the left renal vein due to propagation of thrombus on the proximal surface of the UF. The right renal vein was not affected. The patient made an uneventful recovery after removal of the UF. The other patient died without permission for autopsy being obtained. Postoperative septicemia led to removal of the UF in one patient on the seventh day after implantation. The organisms cultured from the blood and from the clot on the proximal surface of the UF were identical.
Staffs Sequelae Of the 2215 patients with filter implants, 115 (5.1%) developed significant clinical edema and 35 (1.5%) phlebitis of the lower extremities not
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previously present. The majority of these patients improved with standard medical treatment. DISCUSSION
Patients with nonfatal pulmonary emboli may be managed by the administration of anticoagulants, with or without interruption of the IVC. Unfortunately, there has been a wide variation in the reported results with anticoagulant therapy. Murray 1~ notes a recurrence rate of only 2.6% nonfatal emboli in 149 patients, but Barker is recorded an incidence of 78.6% in a group of 28. Barritt and Jordan 19 had no fatal recurrences with anticoagulant therapy in 54 patients while Ocshner 2~ and Byrne 2~ reported fatal recurrent pulmonary emboli in 11.7 and 18.6% of their study groups, respectively. The reasons for such conflicting reports are not hard to find; as one analyzes these reports, one is struck with the variability in patient material, diagnostic and therapeutic criteria, and interpretation of facts. Debakey 22 in an exhaustive review of literature on venous thromboembolism, pointed out that inconsistencies, conflicting findings, and incompatible statistics keynote all phases of thromboembolism. The clinical diagnosis of venous thrombosis and pulmonary embolism is unreliable and the results of treatment will continue to vary. Diacoff and Associates 23 diagnosed pulmonary embolism in only 21 of 57 patients (36.8%) who had arteriography for suspected pulmonary embolism. It seems unrealistic to compare and evaluate the results of therapy when the very diagnosis of thromboembolism is uncertain. The Urokinase-pulmonary embolism trial ~ phase I, a national cooperative study, has provided an excellent opportunity to document the course of the disease in patients with proven pulmonary embolism. The group reported 18% recurrence rate (fatal 9%) in 60 patients treated with adequate anticoagulation. When one analyzes the reasons for failure of anticoagulant therapy to prevent recurrent pulmonary embolism, it becomes apparent that heparin in adequate doses may prevent thrombus formation or propagation, but cannot prevent fragmentation and detachment of a nonadherent thrombus. Nearly all emboli arise from the thrombi in the lower extremity or pelvic veins. Major or fatal emboli come from the large deep veins of the thigh or pelvis. Leg vein thrombi may become significant if thrombus extends into the popliteal vein or if
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Fig. 4. (A) The patient is placed supine on an x-ray tilt-table, with the head 45 ~ from the horizontal. Fifty cc of 60% Hypaque is injected simultaneously in the subcutaneous veins of both feet with tourniquets above the ankle. Films of the leg and thigh region are exposed in rapid succession. (B) Both lower extremities are raised to 45 ~ and a film of the pelvis and abdomen is exposed. Intravenous fluids are administered to wash out the contrast media.
Fig. 5.
IVC.
thrombosis is extensive. Clinical evaluation detects less than one-half the cases of deep venous thrombosis and pulmonary embolism is often the first manifestation of this disease. Phlebography provides the most reliable evidence for the presence, and extent of venous thrombosis by demonstration of filling defects within the vein. A negative phlebogram essentially rules out significant deep venous thrombosis of the lower extremities. Phlebography has not been used widely in the past, largely because of technical problems and questions of interpretation. However, there now seems sufficient experience with this technique 2s-28 to warrant its use in selected patients with thromboembolism. At our institution, it is used routinely as part of work-up in patients with thromboembolic disease to determine the extent of residual venous thrombosis. The phlebographic technique used is described in Fig. 4. Peripheral phlebograms gave adequate visualization of the major veins of the lower extremities and pelvis including the IVC (Fig. 5). In our experience, recurrent pulmonary embolism during "adequate" anticoagulation therapy has occurred most frequently in those patients in whom nonadherent thrombi were demonstrated by phlebography. A fresh nonadherent thrombus appears as a radiolucent defect within the vein with the contrast medium lining the vein wall, (Fig. 6). It is our practice to recommend IVC interruption by the UF in those patients who have potentially
Peripheral phlebograms, demonstrating the deep venous system of the lower extremities, the iliac veins and the
INFERIOR VENA CAVA UMBRELLA FILTER
397
Fig. 6. (A| Pulmonary arteriogram in a patient demonstrating more than 50% embolic obstruction to pulmonary blood flow. (B) Phlebogram demonstrating potentially lethal, nonadherent thrombus in iliofemoral vein. (C) Inferior vena cava umbrella filter in place for prevention of fatal pulmonary embolism.
lethal nonadherent thrombi in the iliofemoral veins. As physicians have gained experience with the use of UF, the complication rate has significantly decreased. The main causes of filter migration have been: (1) exceptionally large IVC, (2) inadequate seating of the filter, (3) sudden embolic obstruction of the filter by a massive thrombus, resulting in dilatation of IVC, and permitting dislodgement and migration of the filter along with the embolus. With the introduction of the
larger 28-ram UF, the incidence of migration has been significantly reduced. In an attempt to resist or prevent thrombus formation on the proximal surface of the filter, preoperative heparin impregnation of the UF by treating it with TDMAC/ heparin complex 29 is being evaluated. Postoperatively anticoagulation therapy is continued for 3 too; if there is no contraindication for its use. These measures may prevent thrombus formation (Fig. 7) and allow for endothelium to grow inbetween the fenestrations of the
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Fig. 7. [A) Angiogram of inferior vena cava in a patient 5 days after umbrella implantation. Note complete thrombotic occlusion of IVC and development of collateral circulation. (B) Angiogram of IVC, 3 mo after implantation of heparinimpregnated umbrella filter. Note free flow of blood through the filter.
filter. T r a n s v e n o u s caval i n t e r r u p t i o n b y t h e umbrella filter h a s p r o v i d e d an effective m e a n s for prevention of pulmonary embolism with minimal risk to the p a t i e n t . ACKNOWLEDGMENT This review would not have been possible without the assistance of many physicians. Dr. Samii Parviz of Jackson, Michigan and Dr. Albert M. Schwartz of Beth Israel Medical Center, N.Y., were among the many, who readily responded to our request for information. REFERENCES 1. Hume M, Sevitt S, Thomas DP: Venous Thrombosis and Pulmonary Embolism. Cambridge, Harvard Univ. Press, 1970, p. 4 2. Barker NW, Nygaard KK, Walters W, et al: Statistical Study of Post-operative Venous Thrombosis and Pulmonary Embolism. Proceedings Mayo Clinic, 15:769, 1940 3. Crane C: Femoral vs. caval interruption for venous thromboembolism, New Engl J Ned, 278:819, 1964 4. Nabseth DC, Moran JM: Reassessment of the role of inferior-vena-cava ligation in venous thromboembolism. N Engl J Med 273:1250-1253, 1965 5. Moran JM, CriscitieUo MG, Callow AD: Vena cava interruption for thromboembolism: partial or complete?
Influence of cardiac disease upon results. Circulation 39:" (Suppl) 1 : 263-268, 1969 6. Mobin-Uddin K, Smith PE, Martines LD, et al: A vena caval f'dter for the prevention of pulmonary embolus. Surg Forum 18:209, 1967 7. Mobin-Uddin K, McLean R, Bolooki H e t al: Caval interruption for prevention of pulmonary embolism; Long term results of a new method. Arch Surg 99:711, 1969 8. Mobin-Uddin K, Bolooki H, Jude JR" Intravenous caval interruption for pulmonary embolism in cardiac _disease. Circulation 41 (Suppl 2): 153, 1970 9. Mobin-Uddin K, Trinkle JK, Bryant LR: Present status of the inferior vetaa cava umbrella filter. Surgery 70:914, 1971 10. Mobin-Uddin K, CaUard GM, Bolooki H, et al: Transvenous caval interruption with umbrella filter. N Engl J Med 286:55, 1972 11. Gray RK, Buckberg GD, Grollman JH: The importance of inferior vena cavography in placement of the Mobin-Uddin vena caval fdter, Diagnostic Radiology 106: 277, 1973 12. Meier MA, Burman SO, Hastreiter AR et al: Interruption of double inferior vena cava for prevention of pulmonary embolism Ann Surg 76:769 1971 13. Riggs OE: Vena cavography relative to umbrella filter placement. Radiology 105:450, 1972 14. Bloomfield DA: The use of intra caval umbrella filters in massive pulmonary embolism, in Mobin-Uddin
INFERIOR V E N A CAVA U M B R E L L A FILTER
(ed): Pulmonary Thromboembolism. Illinois, Thomas, (in press) 15. Huse WM: Vena cava umbrella filter insertion durhag pulmonary embolectomy, Arch Surg 106: 737, 1973 16. Fullen WD, Miller EH, Steele WF, et al: Prophylactic vena caval interruption in hip fractures. J Trauma 13: 403, 1973 17. Murray G: Anticoagulants in venous thrombosis and prevention of pulmonary embolism. Surg Gynecol Obstet 84:665, 1947 18. Barker WF: The management o f venous thrombosis and pulmonary embolism. Surgery 45:198, 1959 19. Barritt DW, Jordan SC: Anticoagulant drugs in treatment of pulmonary embolism: Controlled trial. Lancet 1:1309, 1960 20. Ocshner A, Debakey ME, DeCamp PT, et al: Thromboembolism. An analysis of cases at the Charity Hospital in New Orleans over a 12 year period. Ann Surg 134:405, 1951 21. Byrne JJ: Phlebitis; A study of 979 cases at the Boston City Hospital. JAMA 174:113, 1960 22. Debakey M, Collective Review: Critical evaluation
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of problems of thromboembolism. Int Abst Surg 98:1, 1954 23. Diacoff GR, Ranninger K, Moulder PV: The diagnosis and management of massive pulmonary embolism. Surg Clin North Am 48:71, 1968 24. The Urokinase pulmonary embolism trial, A national cooperative study: Circulation XLVII No. 4 (Suppl 11), 1973 25. DeWeese JA, Rogoff SM: Functional ascending phlebography of the lower extremity by serial long film technique. Am J Roentgen Radium Ther Nucl Med 81: 841, 1959 26. Bergvall U: Phlebography in acute deep venous thrombosis of the lower extremity. Aeta Radiol (Diagn) (Stockholm) 11:148, 1971 27. Nicolaides AN, Kakkar VV, Field ES, et al: The origin of deep vein thrombosis: A venographic study, Brit J Radio144:653, 1971 28. Rabinov K, Pa,ulin S; Roentgen diagnosis of venous thrombosis in the leg./,Arch Surg (Chicago) 104:134, 1972 29. Grode GA, FaPo RD, Crowley JP: Bio-compatible materials for use in tile vascular system. J Biomed Mater Res 3:77--84, 1972
HROMBOEMBOLIC DISEASE is a major cause of morbidity and mortality in hospitalized patients. Pulmonary embolism is one of the most common lethal processes found at autopsy. It has been estimated that approximately 570,000 patients suffer nonfatal pulmonary embolism and 140,000 patients suffer fatal pulmonary embolism in the United States each year. Barker and associates 2 have reported on the natural course of untreated thromboembolism in postoperative patients. Of 1655 patients with pulmonary embolism, the first episode was fatal in 24.4%, and death occurred in 18.3% of the nearly one-third who had recurrent embolism. Despite anticoagulant therapy that has been considered adequate, recurrences of pulmonary embolism are not uncommon. Interruption of the inferior vena cava (IVC), by either ligation or plication, has offered good protection against recurrent embolism with the risk of a major surgical procedure and anesthesia. The operative mortality rate in patients with significant cardiopulmonary disease has been high a-s depending upon the severity of the underlying disease and the extent of obstruction to pulmonary blood flow. To avoid general anesthesia and a major surgical operation, a simple transvenous catheter technique was developed for interruption of the IVC with an intracaval device of an umbrella design. 6-~~ After satisfactory studies in dogs and an assessment of clinical results in the first t00 patients, the umbrella filter* (UF) was released for general clinical use in January 1970. The present report includes the results of clinical filter implants in 2215 patients as reported by the evaluating physicians.
T
MATERIALS AND METHODS The intracaval filter (Fig. 1) is of an umbrella design and consists of six spokes of stainless steel alloy1" radiating from a central hub. A thin sheet of silasticr covers
From the Department of Surgery, Division o f Cardiothoracic Surgery, University of Kentucky Medical Center, Lexington, Ky. Reprint requests should be addressed to Kazi MobinUddin, M.B., B.S., Section o f Cardiovascular Surgery, Fredric C. Smith Clinic, 1040 Delaware Avenue, Marion, Ohio, 43302. 9 1975 by Grune & Stratton, Inc.
the metal on each side, but the spokes extend 2 mm beyond the silastic "body". There is a 1-mm threaded hole in the center. There are 18 fenestrations in the silastic body, each with a diameter of 3 ram. The threaded hole in the center provides fixation to the styler for implantation. The original caval umbrella was 23 mm in diameter, but episodes of filter migration led to development of the 28-mm device. By virtue of its spring action, the large filter will adjust to all sizes of the IVC in adults. The catheter used for implantation of the umbrella consists of a No. 7 cardiac catheter with a metal capsule at the end. The capsule has a diameter of 7 mm and a length of 32 mm. A threaded stylet fits inside the catheter and capsule for control of the filter. The UF is threaded onto the end of the styler and is unscrewed one-half turn (Fig. 2). Using a swab, the umbrella and the inner surface of the loading cone are lubricated with a sterile, water soluble lubricant (Lubrifax, K.Y. Jelly, or Glyserine) mixed with a few milliliters of heparin. The UF i s pushed all the way into the distal portion of the loading cone and the applicator-capsule is advanced firmly into the loading cone. An assistant is particularly useful in holding rite applicator capsule inside the loading cone. While maintaining the axial alignment, the stylet, with the help of a pinwise, is pulled back through the applicator, thus loading the UF into the capsule. The pin wise is advanced onto the luerlok hub of the applicator and retightened to prevent the umbrella filter from being accidentally ejected from the capsule or unscrewed from the stylet while manipulating the catheter.
Umbrella Filter Implantation Under local infiltration anesthesia, a small incision is made at rite right base of rite neck and rite right internal jugular vein is isolated between the two heads of the sternocleidomastoid muscle. A vascular clamp is applied proximally to occlude the vein and an umbilical tape tourniquet is put in place for distal control. The vascular clamp and tourniquet are very important for the prevention of air embolism and bleeding. The applicator-capsule containing the collapsed UF is inserted via a venotomy in the internal jugular vein (Fig. 3) and advanced under fiuroscopic control through the superior vena cava and right atrium in the IVC. The applicator is generally advanced to the level of the bifurcation of the 1VC and it is then withdrawn so that the distal tip of the capsule is positioned at the level of the midpoint of the third lumbar vertebra. The pin wise is loosened, moved 2 cm proximally, and then retightened. After rechecking the position of the distal capsule under fluorscopy, the styler is advanced by pushing on the pin wise and the filter is ejected from the *Edwards Laboratories, Santa Ana, Calif. t Elgiloy Company, Elgin, IlL Dow Coming Corporation, Midland, Mich.
Progress in Cardiovascular Diseases, Vol. XVI I, No. 5 (March/April), 1975
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MOBIN-UDDIN, UTLEY, AND B R Y A N T
clamp is placed on the vein distally, and the vessel is repaired before wound closure.
TECHN ICAL CONSIDERATIONS
Fig. 1. (A) To the right is the 28-mm filter now recommended for use in all adult patients. The 23-mm filter may have application in patients less than 125 pounds. (B) Catheter used for umbrella filter implantation.
capsule. The filter should spring open and lightly fix in place at the intervertebral disc between the third and fourth lumbar vertebra. The pin wise is moved 2 cm proximal to the luerlok hub and retightened. Slight, but finn upward traction is applied several times on the stylet to securely fix the filter into place. Slight upward traction is maintained while the stylet is unscrewed from the filter. The applicator is withdrawn from the vein, a vascular
The following operative details are emphasized: (1) Special care should be exercised in dissecting the adherent posterior wall of the internal juglar vein. The clavicular head of the sternocleidomastoid muscle may be divided to improve exposure. (2) The venotomy should be kept closed except during the actual insertion of the applicator capsule to avoid air embolism. (3) Occasionally, difficulty is experienced in advancing the applicator-capsule from the juglar vein into the superior vena cava. It usually hangs up in the vein under the clavicle. The following measures may prove helpful: handle the vein as little as possible to prevent spasm; allow the umbrella to protrude slightly at the end of the capsule to form a "bullet nose"; pass a suitable size Hagar dilator via the venotomy site and note the direction of opening into the superior vena cava; insert the applicator-capsule half-way into the vein, release the distal tape and apply slight counter-traction with the proximal tape, before advancing the applicator in the direction previously noted; do not use force to advance the applicator. Slight lubrication of the applicator-capsule may be helpful. (4) At times the applicator may not pass from the right atrium into the IVC, or it may pass preferentially into the right renal or hepatic vein. Under these circumstances, the applicator is withdrawn into the neck and a slight gentle bend is made in the applicator catheter, just proximal to the capsule. The applicator can then be maneuvered by rotating it past the obstruction. Rarely,
Fig. 2, Demonstrates the technique of loading the umbrella filter into the applicator-capsule,
INFERIOR VENA CAVA UMBRELLA FILTER
393
Fig, 3. (A) The applicator-capsule containing the collapsed umbrella filter has been inserted via the right internal jugular vein into the inferior vena cava below the renal veins. (BJ The filter has been ejected from the capsule into the inferior vena cava. (C) The stylet has been unscrewed from the filter and the applicator has been withdrawn,
because of a prominent eustachian valve, the applicator-capsule cannot be advanced from the right atrium into the IVC. Under such circumstances, a guide wire is inserted via the jugular vein into the IVC. After turning the patient to one side, the applicator can then be easily manipulated into the IVC. (5) An inferior venacavogram made before umbrella insertion is a very valuable adjunct. It demonstrates the level of the renal veins and the size of the IVC, and it may reveal any unsuspected anatomical abnormalities of the IVC n-12 or the renal veins, x3 Any thrombus in the IVC that may interfere with placement of the UF can also be detected. (6) Accidental placement of the UF in the IVC above the renal veins can be corrected by displacing the filter downward by the applicator-capsule to a level below the renal veins. POSTOPERATIVE MANAGEMENT
Following UF implantation, anticoagulant therapy is withheld for 12 hr to minimize the possibility of retroperitoneal bleeding. Thereafter, intravenous heparin is resumed for 7-10 days, preferably
by continuous infusion to maintain the partial thromboplastin time or the Lee-White clotting time at two times the control value, Oral anticoagulation with Warfarin sodium is started on the 3rd postoperative day and continued for 3 mo. Patients with continued predisposing factors such as cardiac failure and those with chronic obstructive airway disease associated with microemboli and cor pulmonale receive long-term anticoagulants after UF insertion. Elevation, elastic support, and early ambulation are employed to prevent or control peripheral edema. SELECTION OF PATIENTS FOR U M B R E L L A PROCEDURE
Initially IVC interruption with the UF was used only in poor risk patients for whom surgical ligation or plication would have carried a higher operative risk. A large number of physicians who have gained experience with the umbrella procedure are now using it as the method of choice. The UF has been used in patients who have recurrent pulmonary embolism despite adequate
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MOBIN-UDDIN, UTLEY, A N D B R Y A N T Table 1. Summary of Clinical Results in Patients Treated with the Umbrella-Filter as of November 1973 No. of Patients
F liter I mplants Proximal filter migration Distal filter migration* Filter dislodgement without migration Misplacement of filter Right renal vein Right lilac vein Recurrent emboli Fatal Nonfatal Clinical edema Phlebitis
23 mrn Filter 1,981
28 mm Filter 234
Total No. of Patients 2,21 5
20 6 20
2 0 0
22%-0.9% 6%-0,27% 20%-0.9%
7 20
0 0
7%-0.3% 20%-0.9%
18 47 102 33
0 6 13 2
18%-0.8% 53%-2.3% 115%-5.1% 35%-1.5%
*Following closed cardiac massage.
anticoagulation therapy, in those for whom anticoagulants are contraindicated, in patients with pulmonary embolism and shock, 14 and following pulmonary embolectomy, is Prophylactic caval interruption with the UF has been used in high risk patients with recent deep venous thrombosis while awaiting a surgical procedure, in those with iliofemoral thrombosis that has not responded to medical management and in a controlled study group before hip nailing. 16
Results The results are summarized in Table 1. In 71 patients the UF could not be implanted mainly because of the inability to insert the applicatorcapsule via the right internal jugular vein. In five of these patients, the left internal jugular vein and in one the right common femoral vein, was used to implant the UF.
Mortality and Recurrent Embolism Of the 2215 patients in whom the UF was implanted, recurrent embolism has been reported in 3.0% (fatal, 0.8%). For three patients, blood clot from the proximal surface of the UF was implicated as the source of recurrent pulmonary emboli. FILTER MIGRATION
The clinical data of patients in whom filter migration occurred is summarized in Table 2. Filter migration has occurred in two of the 234 patients who have received the larger 28-mm filter. Of the 1981 patients in whom a 23-mm filter was used, proximal migration occurred in 20 instances.
The filter lodged in a main branch of the pulmonary artery in 13 patients, in the right ventricle in two, in right atrium in four, and in the IVC above the renal veins in three patients. Distal migration of the UF into the right iliac vein following closed cardiac massage has been reported in six patients.
Filter Dislodgement Without Migration Partial dislodgement of the UF without migration has been reported in 20 patients. To prevent migration, the larger 28-ram filter was implanted just above the previous filter in six patients. In the remaining patients, either nothing was done or Table 2. Clinical Data on Patients with Umbrella-Filter Dislodgement and Proximal Migration No. of Patients 13
Filter Migrated To:
Pulmonary artery 3 Fatal-embolized with massive thrombus 7 R e m o v e d - t w o died postoperatively 3 Left in place1 died few days later and 2 died after 3 months, death unrelated. Right ventricle 1 Removed on cardiopulmonary bypass 1 Died 6 days later, no autopsy Right atrium 1 Fatal-embolized along with massive thrombus 1 Found at autopsy, death unrelated 2 Removed, 1 died postoperatively Suprarenal inferior vena cava 1 Died of cancer at 6 wk 1 Died of myocardial infarction 1 yr later 1 Alive and well. Venogram showed patency of I VC.
INFERIOR VENA CAVA UMBRELLA FILTER
surgical interruption of the IVC was performed with or without removal of the filter.
Misplacement of the Filter The UF has been improperly placed in the suprarenal IVC, the right renal vein and the right iliac vein. In three patients in whom the UF was accidentally extruded into the suprarenal IVC, the filters could be pushed downward with the applicator-capsule into the IVC below the renal veins. In two of these patients, a second filter was implanted proximal to the first because the latter became tilted as it was moved downward by the applicator-capsule. Of the seven patients in whom the UF was inadvertently misplaced in the right renal vein, in three, the UF has been removed and IVC interrupted by direct surgical approach. The UF was mistakenly placed in the right iliac vein in 20 patients. These have been treated either by removing the filter with interruption of the IVC or by implanting an additional filter in the IVC. In one patient, the applicator-capsule accidentally perforated the hepatic vein and the umbrella was extruded into the retroperitoneal space. Significant retroperitoneal hematoma has been reported in five patients, right recurrent laryngeal nerve injury in two, and perforation of duodenum and ureter in one patient each. Air embolism during filter insertion has occurred in two patients, (fatal in one). Acute renal failure developed postoperatively in two patients in whom the UF was placed just below the renal veins. Exploratory laparotomy in one patient revealed an impingement on the blood flow from the left renal vein due to propagation of thrombus on the proximal surface of the UF. The right renal vein was not affected. The patient made an uneventful recovery after removal of the UF. The other patient died without permission for autopsy being obtained. Postoperative septicemia led to removal of the UF in one patient on the seventh day after implantation. The organisms cultured from the blood and from the clot on the proximal surface of the UF were identical.
Staffs Sequelae Of the 2215 patients with filter implants, 115 (5.1%) developed significant clinical edema and 35 (1.5%) phlebitis of the lower extremities not
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previously present. The majority of these patients improved with standard medical treatment. DISCUSSION
Patients with nonfatal pulmonary emboli may be managed by the administration of anticoagulants, with or without interruption of the IVC. Unfortunately, there has been a wide variation in the reported results with anticoagulant therapy. Murray 1~ notes a recurrence rate of only 2.6% nonfatal emboli in 149 patients, but Barker is recorded an incidence of 78.6% in a group of 28. Barritt and Jordan 19 had no fatal recurrences with anticoagulant therapy in 54 patients while Ocshner 2~ and Byrne 2~ reported fatal recurrent pulmonary emboli in 11.7 and 18.6% of their study groups, respectively. The reasons for such conflicting reports are not hard to find; as one analyzes these reports, one is struck with the variability in patient material, diagnostic and therapeutic criteria, and interpretation of facts. Debakey 22 in an exhaustive review of literature on venous thromboembolism, pointed out that inconsistencies, conflicting findings, and incompatible statistics keynote all phases of thromboembolism. The clinical diagnosis of venous thrombosis and pulmonary embolism is unreliable and the results of treatment will continue to vary. Diacoff and Associates 23 diagnosed pulmonary embolism in only 21 of 57 patients (36.8%) who had arteriography for suspected pulmonary embolism. It seems unrealistic to compare and evaluate the results of therapy when the very diagnosis of thromboembolism is uncertain. The Urokinase-pulmonary embolism trial ~ phase I, a national cooperative study, has provided an excellent opportunity to document the course of the disease in patients with proven pulmonary embolism. The group reported 18% recurrence rate (fatal 9%) in 60 patients treated with adequate anticoagulation. When one analyzes the reasons for failure of anticoagulant therapy to prevent recurrent pulmonary embolism, it becomes apparent that heparin in adequate doses may prevent thrombus formation or propagation, but cannot prevent fragmentation and detachment of a nonadherent thrombus. Nearly all emboli arise from the thrombi in the lower extremity or pelvic veins. Major or fatal emboli come from the large deep veins of the thigh or pelvis. Leg vein thrombi may become significant if thrombus extends into the popliteal vein or if
396
MOBIN-UDDIN, UTLEY, AND BRYANT
Fig. 4. (A) The patient is placed supine on an x-ray tilt-table, with the head 45 ~ from the horizontal. Fifty cc of 60% Hypaque is injected simultaneously in the subcutaneous veins of both feet with tourniquets above the ankle. Films of the leg and thigh region are exposed in rapid succession. (B) Both lower extremities are raised to 45 ~ and a film of the pelvis and abdomen is exposed. Intravenous fluids are administered to wash out the contrast media.
Fig. 5.
IVC.
thrombosis is extensive. Clinical evaluation detects less than one-half the cases of deep venous thrombosis and pulmonary embolism is often the first manifestation of this disease. Phlebography provides the most reliable evidence for the presence, and extent of venous thrombosis by demonstration of filling defects within the vein. A negative phlebogram essentially rules out significant deep venous thrombosis of the lower extremities. Phlebography has not been used widely in the past, largely because of technical problems and questions of interpretation. However, there now seems sufficient experience with this technique 2s-28 to warrant its use in selected patients with thromboembolism. At our institution, it is used routinely as part of work-up in patients with thromboembolic disease to determine the extent of residual venous thrombosis. The phlebographic technique used is described in Fig. 4. Peripheral phlebograms gave adequate visualization of the major veins of the lower extremities and pelvis including the IVC (Fig. 5). In our experience, recurrent pulmonary embolism during "adequate" anticoagulation therapy has occurred most frequently in those patients in whom nonadherent thrombi were demonstrated by phlebography. A fresh nonadherent thrombus appears as a radiolucent defect within the vein with the contrast medium lining the vein wall, (Fig. 6). It is our practice to recommend IVC interruption by the UF in those patients who have potentially
Peripheral phlebograms, demonstrating the deep venous system of the lower extremities, the iliac veins and the
INFERIOR VENA CAVA UMBRELLA FILTER
397
Fig. 6. (A| Pulmonary arteriogram in a patient demonstrating more than 50% embolic obstruction to pulmonary blood flow. (B) Phlebogram demonstrating potentially lethal, nonadherent thrombus in iliofemoral vein. (C) Inferior vena cava umbrella filter in place for prevention of fatal pulmonary embolism.
lethal nonadherent thrombi in the iliofemoral veins. As physicians have gained experience with the use of UF, the complication rate has significantly decreased. The main causes of filter migration have been: (1) exceptionally large IVC, (2) inadequate seating of the filter, (3) sudden embolic obstruction of the filter by a massive thrombus, resulting in dilatation of IVC, and permitting dislodgement and migration of the filter along with the embolus. With the introduction of the
larger 28-ram UF, the incidence of migration has been significantly reduced. In an attempt to resist or prevent thrombus formation on the proximal surface of the filter, preoperative heparin impregnation of the UF by treating it with TDMAC/ heparin complex 29 is being evaluated. Postoperatively anticoagulation therapy is continued for 3 too; if there is no contraindication for its use. These measures may prevent thrombus formation (Fig. 7) and allow for endothelium to grow inbetween the fenestrations of the
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MOBIN-UDDIN, UTLEY, AND BRYANT
Fig. 7. [A) Angiogram of inferior vena cava in a patient 5 days after umbrella implantation. Note complete thrombotic occlusion of IVC and development of collateral circulation. (B) Angiogram of IVC, 3 mo after implantation of heparinimpregnated umbrella filter. Note free flow of blood through the filter.
filter. T r a n s v e n o u s caval i n t e r r u p t i o n b y t h e umbrella filter h a s p r o v i d e d an effective m e a n s for prevention of pulmonary embolism with minimal risk to the p a t i e n t . ACKNOWLEDGMENT This review would not have been possible without the assistance of many physicians. Dr. Samii Parviz of Jackson, Michigan and Dr. Albert M. Schwartz of Beth Israel Medical Center, N.Y., were among the many, who readily responded to our request for information. REFERENCES 1. Hume M, Sevitt S, Thomas DP: Venous Thrombosis and Pulmonary Embolism. Cambridge, Harvard Univ. Press, 1970, p. 4 2. Barker NW, Nygaard KK, Walters W, et al: Statistical Study of Post-operative Venous Thrombosis and Pulmonary Embolism. Proceedings Mayo Clinic, 15:769, 1940 3. Crane C: Femoral vs. caval interruption for venous thromboembolism, New Engl J Ned, 278:819, 1964 4. Nabseth DC, Moran JM: Reassessment of the role of inferior-vena-cava ligation in venous thromboembolism. N Engl J Med 273:1250-1253, 1965 5. Moran JM, CriscitieUo MG, Callow AD: Vena cava interruption for thromboembolism: partial or complete?
Influence of cardiac disease upon results. Circulation 39:" (Suppl) 1 : 263-268, 1969 6. Mobin-Uddin K, Smith PE, Martines LD, et al: A vena caval f'dter for the prevention of pulmonary embolus. Surg Forum 18:209, 1967 7. Mobin-Uddin K, McLean R, Bolooki H e t al: Caval interruption for prevention of pulmonary embolism; Long term results of a new method. Arch Surg 99:711, 1969 8. Mobin-Uddin K, Bolooki H, Jude JR" Intravenous caval interruption for pulmonary embolism in cardiac _disease. Circulation 41 (Suppl 2): 153, 1970 9. Mobin-Uddin K, Trinkle JK, Bryant LR: Present status of the inferior vetaa cava umbrella filter. Surgery 70:914, 1971 10. Mobin-Uddin K, CaUard GM, Bolooki H, et al: Transvenous caval interruption with umbrella filter. N Engl J Med 286:55, 1972 11. Gray RK, Buckberg GD, Grollman JH: The importance of inferior vena cavography in placement of the Mobin-Uddin vena caval fdter, Diagnostic Radiology 106: 277, 1973 12. Meier MA, Burman SO, Hastreiter AR et al: Interruption of double inferior vena cava for prevention of pulmonary embolism Ann Surg 76:769 1971 13. Riggs OE: Vena cavography relative to umbrella filter placement. Radiology 105:450, 1972 14. Bloomfield DA: The use of intra caval umbrella filters in massive pulmonary embolism, in Mobin-Uddin
INFERIOR V E N A CAVA U M B R E L L A FILTER
(ed): Pulmonary Thromboembolism. Illinois, Thomas, (in press) 15. Huse WM: Vena cava umbrella filter insertion durhag pulmonary embolectomy, Arch Surg 106: 737, 1973 16. Fullen WD, Miller EH, Steele WF, et al: Prophylactic vena caval interruption in hip fractures. J Trauma 13: 403, 1973 17. Murray G: Anticoagulants in venous thrombosis and prevention of pulmonary embolism. Surg Gynecol Obstet 84:665, 1947 18. Barker WF: The management o f venous thrombosis and pulmonary embolism. Surgery 45:198, 1959 19. Barritt DW, Jordan SC: Anticoagulant drugs in treatment of pulmonary embolism: Controlled trial. Lancet 1:1309, 1960 20. Ocshner A, Debakey ME, DeCamp PT, et al: Thromboembolism. An analysis of cases at the Charity Hospital in New Orleans over a 12 year period. Ann Surg 134:405, 1951 21. Byrne JJ: Phlebitis; A study of 979 cases at the Boston City Hospital. JAMA 174:113, 1960 22. Debakey M, Collective Review: Critical evaluation
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of problems of thromboembolism. Int Abst Surg 98:1, 1954 23. Diacoff GR, Ranninger K, Moulder PV: The diagnosis and management of massive pulmonary embolism. Surg Clin North Am 48:71, 1968 24. The Urokinase pulmonary embolism trial, A national cooperative study: Circulation XLVII No. 4 (Suppl 11), 1973 25. DeWeese JA, Rogoff SM: Functional ascending phlebography of the lower extremity by serial long film technique. Am J Roentgen Radium Ther Nucl Med 81: 841, 1959 26. Bergvall U: Phlebography in acute deep venous thrombosis of the lower extremity. Aeta Radiol (Diagn) (Stockholm) 11:148, 1971 27. Nicolaides AN, Kakkar VV, Field ES, et al: The origin of deep vein thrombosis: A venographic study, Brit J Radio144:653, 1971 28. Rabinov K, Pa,ulin S; Roentgen diagnosis of venous thrombosis in the leg./,Arch Surg (Chicago) 104:134, 1972 29. Grode GA, FaPo RD, Crowley JP: Bio-compatible materials for use in tile vascular system. J Biomed Mater Res 3:77--84, 1972
