The Journal of Emergency Medicine, Vol. 47, No. 5, pp. 546–551, 2014 Copyright Ó 2014 Elsevier Inc. Printed in the USA. All rights reserved 0736-4679/$ - see front matter
http://dx.doi.org/10.1016/j.jemermed.2014.07.028
Selected Topics: Critical Care EMERGENT RECONNECTION OF A TRANSECTED LEFT VENTRICULAR ASSIST DEVICE DRIVELINE Efrain Israel Cubillo IV, MD, Ricardo A. Weis, MD, and Harish Ramakrishna, MD, FASE Division of Cardiovascular and Thoracic Anesthesiology, The Mayo Clinic, Phoenix, Arizona Reprint Address: Harish Ramakrishna, MD, FASE, Division of Cardiovascular and Thoracic Anesthesiology, The Mayo Clinic Phoenix, 5777 East Mayo Boulevard, Phoenix, AZ 85054
, Keywords—mechanical circulatory systems; left ventricular assist device; driveline transection; driveline rewiring; HeartWare
, Abstract—Background: Recent clinical advances with new mechanical circulatory systems have led to additional strategies in the treatment of end-stage heart failure. The third-generation HeartWare Left Ventricular Device (LVAD) System utilizes a blood pump and a driveline (cable) that exits the patient’s skin connecting the implanted pump to an externally worn controller. We report a rare case of a HeartWare LVAD driveline rewiring after accidental (presumed) transection of the driveline system. Case Report: A 67-year-old male with a medical history of ischemic cardiomyopathy status post HeartWare LVAD implantation presented to the emergency department (ED) after acute LVAD failure. On the morning of presentation, he attempted to cut the paper tape off of his adult diaper with scissors and accidentally (presumed) and unwitnessed severed the driveline system. The patient immediately went into cardiac arrest and was transported to a regional medical center. On arrival, he exhibited no appreciable vital signs and was subsequently intubated, vascular access was placed, and inotropic support initiated. The emergency physician individually stripped and reconnected the color-coded driveline wires using multiple hemostats, electrical tape, and cardboard, which resulted in regeneration of positive LVAD flows. Why Should an Emergency Physician Be Aware of This?: VAD patients will present in extremis typically to the ED with manifestations of pump dysfunction ranging from diminished flows needing fluid management or pump adjustments to full pump failure manifesting as cardiogenic shock, needing rapid resuscitation and transfer to a cardiothoracic surgical unit with on-site VAD-perfusion specialists. Ó 2014 Elsevier Inc.
INTRODUCTION While the population of patients with congestive heart failure has risen to > 5 million Americans and resulted in 282,000 annual deaths, the available transplantation population has remained stagnant at approximately 2000 donors per year (1,2). Recent advances and implementation of left ventricular assist devices (LVADs) have dramatically changed the lifestyles of patients with chronic heart failure. VAD implantation has grown from 280 implants per year in 2007 to 1450 implants in 2011 (3). As a result, > 5500 Americans are living with VADs and many more are expected, given the aging of the ‘‘baby-boomer’’ generation (3,4). The LVAD system in general utilizes a blood pump and a percutaneous driveline consisting of an electrical connection to the external controller and a pneumatic conduit that allows atmospheric venting or emergent pneumatic hand pumping (5,6). The Heartware LVAD is one of the new-generation, axial flow devices that is designed for left ventricular support. Its main advantage compared to its predecessors is its smaller size and compact design, which does not require the creation of a preperitoneal pocket during implantation. Its driveline is significantly thinner than the previous generation of
RECEIVED: 13 March 2014; FINAL SUBMISSION RECEIVED: 24 June 2014; ACCEPTED: 1 July 2014 546
Reconnection of a Transected LVAD
547
to report a fatal VAD malfunction of an axial flow Heartware assist device (11). CASE REPORT
Figure 1. Animated view of HeartWare left ventricular assist device basic components/function.
devices. Constructed with conductor wires used in pacemakers, the driveline of the HeartWare LVAD (Figure 1) maintains durability through a protective woven polyester outer sheath (7). Although constructed with a protective outer sheath and fatigue-resistant cables, the driveline is thin (4.2 mm) and flexible, therefore, a primary source of damage (3,8). The multilayer assembly separates individual conductors, thereby theoretically avoiding abrasion. In addition, due to its percutaneous location, drivelines are significant sources of infection (9,10). Indeed, the driveline of VADs is considered by many to be the ‘‘Achilles heel’’ of these devices. The HeartWare Ventricular Assist System implanted in the patient described in our case report obtained U.S. market approval in November 2012 from the U.S. Food and Drug Administration as a bridge-to-transplantation therapy for patients with advanced-stage heart failure. The HeartWare System has been commercially available in other global markets, including Europe and Australia, since 2009. To date, nearly 4000 patients worldwide have been treated with the HeartWare Ventricular Assist System (5,6). The technical improvements and proven success of implantable VADs have made it a reasonable treatment option in these patients as a bridge to cardiac transplantation, bridge to recovery, or destination therapy. We report a rare (so far unreported in the United States) case of a patient fatality after accidental (presumed) Heartware LVAD driveline transection, which was followed by emergency department (ED) attempts of rapid driveline repair. The future of LVAD technology and the psychological aspects surrounding this event are also discussed. To date, there are no reports of successful LVAD rewiring after driveline transection. In 2010, the European literature described a fatal VAD malfunction in Germany involving disconnection of a right atrial cannula in a Berlin Heart BIVAD. We believe ours is the first case
A 67-year-old male with a medical history of ischemic cardiomyopathy status post HeartWare LVAD implantation as destination therapy 1½ years earlier presented to the ED after acute LVAD failure. On the morning of presentation, the patient was trying to use the bathroom. Sitting on his commode, he attempted to cut the paper tape off of his adult diaper with scissors and accidentally (presumed) and unwitnessed, severed the Heartware LVAD driveline system. Upon disconnection from the LVAD, the systems alarms instantly went off and the patient immediately went into cardiac arrest. Soon thereafter, his wife started chest compressions, which were continued until emergency medical services (EMS) arrived. EMS reported that although he was minimally responsive on their arrival, the patient awoke briefly with initial compressions. What is not known is the length of the period of unwitnessed arrest after driveline transection. The patient was then transported to a regional medical center. On arrival, he had no appreciable vital signs and was subsequently intubated, vascular access was placed and inotropic support initiated. The emergency physician individually stripped and reconnected the color-coded driveline wires using multiple hemostats, electrical tape, and cardboard (Figures 2 and 3A D), which resulted in regeneration of positive LVAD flows. Once the patient was stable, he was emergently transferred to our institution for further definitive management. On arrival, the patient’s baseline rhythm was ventricular tachycardia
Figure 2. Two-view right forearm of patient with six hemostatic clamps around left ventricular assist device (LVAD) driveline with adjacent LVAD controller.
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Figure 3. (A) Superficial view of patient’s right forearm with multiple hemostatic clamps and electrical tape surrounding left ventricular assist device (LVAD) driveline connection. Entire apparatus held by adhesive tape surrounding lateral cardboard. (B) Closer view of hemostatic clamps/electrical tape connecting LVAD driveline. (C) View demonstrating electrical wiring of LVAD driveline with hemostatic clamps providing continuity. (D) Hemostatic clamps connecting appropriate LVAD driveline (cardboard underneath hemostats/driveline wires).
at 175 beats/min with a mean arterial pressure of 40 mm Hg with LVAD flows of 4 L/min. He immediately was cardioverted (200 J), which successfully returned him to sinus rhythm. The patient was placed on dobutamine, epinephrine, norepinephrine, and vasopressin infusions. Urgent transesophageal echocardiogram was performed, which showed flow through the aortic cannula, right ventricular function was mild to moderately depressed, and no pericardial effusion was noted. The patient underwent right heart catheterization with Swan Ganz catheter placement for further invasive hemodynamic monitoring. Results demonstrated a cardiac output of 5.5 L/min and systemic vascular resistance of 814 dyn/cm/s. Pertinent findings on physical examination, included sluggishly reactive pupils, gag reflex present, no withdrawal to pain, and cool distal extremities. On neurological evaluation after 24 h off sedation, the patient maintained brainstem reflexes, although he did not withdraw to pain or have any spontaneous movements. Care was withdrawn on day 7 due to the patients’ poor neurological prognosis. DISCUSSION Over the years, data have continued to accumulate testifying to the broad success that VADs have brought to the definitive management of end-stage heart failure (3,12). However, success and applicability of this therapy are largely limited by high complication rates
associated with these devices. Overall, the most frequent complications include bleeding (especially gastrointestinal), cerebral, and peripheral thromboembolic complications, renal failure, right ventricular failure, and life-threatening dysrhythmias. They can be an entry point for infections (between 14% and 50%) (10). It is not just the driveline, but the entire VAD that is susceptible to infection, including the surgical site, device pocket, driveline, valves, and conduits (10,12,13). Cable lesions and even electrical failures due to material fatigue can occur. It must be appreciated that most VAD patients lead very mobile lives in the community, attached to technology that may not be able to necessarily withstand abuse. Although the incidence of driveline reconnection after disruption of the electrical circuit is a very rare event, Schima et al. reported a quick stabilization method for a patient who survived with a fracture of the outer sheath of a HeartWare HVAD driveline (14). In their report, the metal strands and the electrical functionality were not affected, contrary to our case, where the electrical circuitry was affected with catastrophic results (14). The typical VAD patient has little or no native cardiovascular reserve and is completely pump dependent. Because of this, and the characteristic continuous flow of the HeartWare LVAD, these patients usually have minimal to no palpable pulse, which can be disconcerting to patients, families, and health care providers. Our patient was diabetic, medications also included citalopram, Vicodin, and clonidine. These drugs, as
Reconnection of a Transected LVAD
well as hypoglycemia or hyperglycemia, could have caused mental confusion (15). In addition, fluctuations in VAD flow in every patient create near-constant variations in cardiac output, which could affect brain perfusion from systemic hypoperfusion (16). These variables could affect the patient’s mental status and may have contributed to the event. The ‘‘accidental’’ driveline disruption in our case warranted further investigation with respect to the psychological aspects surrounding this event. Reports from the patients’ family included an intact family support system and no evidence of depression or suicidal intention, although no documented regular psychological followup. Some studies have found a considerable group of LVAD patients to be suffering from a depressive or adjustment disorder (21% and 37% to 50%, respectively) (17). Tigges-Limmer et al. reported a 69-year-old depressed patient who committed suicide by disconnecting the driveline of his LVAD almost 3 years after implantation (18). Psychosocial issues are being increasingly reported in the surgical literature, as the article by Akhter et al. demonstrates (19). The crucial issue, however, seems to be driveline related. The VAD industry has recognized this and technology advances are in the pipeline. The ideal VAD should have a 0% incidence of driveline complications specifically related to infection/driveline disruption, and wireless technologies are sure to be introduced in the not-too-distant future (3,20). In addition, to optimize the management of an increasingly growing population of LVAD patients, direct participation of psychologists, psychiatrists, palliative care specialists, a concise plan of care for anticipated devicerelated complications and a discussion about the longterm financial burden on patients, families, and caregivers is recommended. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS? As the duration of LVAD support is increasing, these patients present numerous challenges to noncardiac care takers, including first responders (EMS), emergency medicine physicians, nurses, pharmacists, and society in general, who are not familiar with the management of these patients who need expert subspecialty care. VAD patients will present in extremis typically to the ED with manifestations of pump dysfunction ranging from diminished flows needing fluid management or pump adjustments to full pump failure manifesting as cardiogenic shock, needing rapid resuscitation and transfer to a cardiothoracic surgical unit with on-site VAD-perfusion specialists. Under resting conditions, all continuous-flow LVAD patients exhibit a loss of pulsatility in the arterial system,
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leading to clinically significant difficulties in noninvasive blood pressure measurement using the standard methods, such as an automated cuff system. This phenomenon can be better understood when one recognizes that arterial pulsatility in LVAD patients is clearly correlated with aortic valve opening. LVAD patient’s exhibit highly variable levels of aortic valve function, ranging from no aortic valve function that manifests in a complete lack of all pulsatility (which can be displayed by the device as a pulsatility index) to intermittent or greater aortic valve function that will produce varying degrees of pulsatility that render noninvasive cuff methods easier in some patients. Invasive arterial monitoring via arterial line is therefore the gold standard, but not always feasible in the outpatient or ED setting. The use of Doppler to measure blood pressure in these patients has been advocated by many LVAD centers (21). There are problems with Doppler, however, it is operator dependent and requires expertise and training. In addition, it is unclear whether one is measuring the mean arterial pressure (MAP) or the systolic blood pressure (SBP). Recently, Lanier et al., in a study investigating blood pressure measurement in LVAD patients, found that there were significant limitations with the Doppler method. In nonpulsatile LVAD patients, Doppler measurement underestimated SBP by approximately 4 mm Hg and overestimated MAP by approximately 9 mm Hg, which would suggest that it more reflected the SBP compared to the MAP, this limitation was more evident when the pulse pressure was increased (when the SBP and MAP are more separated) (22). This has important clinical implications in that confusing SBP and MAP measurements might lead to higher BP medication titration, leading to clinical hypotension. Markham et al., in a recent editorial, suggested that there may be better options, such as the Terumo hybrid design blood pressure monitor, where the cuff deflation speed can be programmed to be much slower for patients with weak or impalpable pulses (23). Slaughter et al., in their guidelines, suggest maintaining MAP in the 70 to 80 mm Hg range for LVAD patients, taking care to avoid an MAP > 90 mm Hg (increased afterload results in LVAD pump output reductions of varying severity) (24). Pulse oximetry, if obtainable, may be unreliable due to diminished pulse pressure. As an index of perfusion, pulse oximetry is another critically important tool in these patients, which is again, limited by non-pulsatility. The best practice is to attempt multiple sites of monitoring (ear lobe, nose, forehead) if one site fails. Cerebral oximetry can be utilized for assessing hemodynamic conditions when more invasive monitoring is not available. To assess perfusion status basic clinical assessments are used, such as the use of mental status, skin color, temperature, auscultation of the LVAD motor, bedside echocardiography, and assessing the machine alarms for low flow indicators.
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The emergency physician may be challenged with managing dysrhythmias in LVAD patients. Ventricular arrhythmias (VA) have been reported to occur in 22% to 59% of LVAD recipients (25). The majority of LVAD patients have automatic implantable cardioverter defibrillators (AICDs) as a standard of care in most LVAD centers. In patients with AICDs, defibrillation can be safely attempted using the existing device and standard electrophysiologic guidance. The presentation of VA in patients with LVADs is variable. Some patients with LVADs can experience right heart failure, hemodynamic deterioration, ICD shocks, and even cardiac arrest with VA caused by impaired right ventricular filling leading to inadequate LVAD flows. Similar to other clinical settings, b-adrenergic antagonists are used as first-line treatment for patients with VA after LVAD. For those who are refractory to b-adrenergic antagonists, intravenous amiodarone and lidocaine can be used acutely. Sotalol can be used as an alternative if amiodarone is not tolerated or there are concerns about toxicities. Finally, close attention to potassium and magnesium levels and avoidance of QT prolonging medications should be considered. In the circumstance that the patient is refractory to pharmacological intervention and becomes unconscious, unresponsive to stimuli, and unobtainable MAP with pump malfunction, cardiopulmonary resuscitation (CPR) should be performed per cardiac arrest protocol. External pads/paddles can be placed in the standard positions with the caveat that nothing should be placed on the device or drivelines. Before initiating CPR, it is vital to assess the audible sounds of the LVAD. If the whirling sound of the LVAD is present, CPR is contraindicated as this may result in cannula dislodgment of the device and death (24,25). Battery issues in LVAD patients are typically rare. The Heartware LVAD in our patient contained two batteries (lithium ion), with each battery providing 4 to 6 h when fully charged, with usage that depends on pump power consumption and the number of charge and discharge cycles. Each patient typically will possess a battery charger that charges 4 batteries at a time. Battery icons are clearly displayed on the device monitor screen with percentages of charge remaining, with an alarm that will sound when < 24% of the battery capacity exists. Most patients travel with two batteries in their patient pack, which holds the Heartware controller and the two batteries. They also have an AC adaptor for use with a wall outlet and a DC adaptor, which can be used for charging the batteries in a car outlet (26). In our case report, the emergency physician should be commended for the rapid troubleshooting and attempted rewiring of the transected driveline. In summary, we aim to reinforce the fact that the driveline continues to be a serious source of VAD morbidity and mortality. Even with rapid resuscitation, as was the
E. I. Cubillo IV et al.
case in our patient, these patients are completely device dependent, with no underlying cardiovascular reserve. Newer generations of this technology are sure to overcome this problem, but until then all clinicians should be aware of the critical importance and vulnerability of the VAD driveline.
REFERENCES 1. Carrela T, Englbergera L, Martinellib M, et al. Continuous flow left ventricular assist devices: a valid option for heart failure patients. Swiss Med Wkly 2012;142:w13701. 2. Lund LH, Matthews J, Aaronson K. Patient selection for left ventricular assist devices. Eur J Heart Fail 2010;12:434–43. 3. Molina E, Boyce S. Current status of left ventricular assist device technology. Semin Thorac Surg 2013;25:56–63. 4. Widmar S, Dietrich M, Minnnick A. How self-care education in ventricular assist device programs is organized and provided: a national study. Heart Lung 2014;43:25–31. 5. Stevenson LW, Rose EA. Left ventricular assist devices: bridges to transplantation, recovery, and destination for whom? Circulation 2003;108:3059–63. 6. Clinical Report, Evaluation of the HeartWare LVAD System for the Treatment of Advanced Heart Failure, HW002, December 22, 2009. 7. US Food and Drug Administration. Medical Devices Heartware Ventricular System-P100047. Available at: https://www.fda.gov/ MedicalDevices/ProductsandMedicalProcedures/DeviceApprovals andClearances/Recently-ApprovedDevices/ucm330838.htm. Accessed January 19, 2014. 8. Shah K, Keyur B, Tang D, et al. implantable mechanical circulatory support: demystifying patients with ventricular assist devices and artificial hearts. Clin Cardiol 2011;34:147–52. 9. Maniar S, Kondareddy S, Topkara V. Left ventricular assist devicerelated infections: past, present and future. Expert Rev Med Devices 2011;8:627–34. 10. Monkowski D, Axelrod P, Fekete T, Hollander T, Furukawa S, Samuel R. Infections associated with ventricular assist devices: epidemiology and effect on prognosis after transplantation. Transpl Infect Dis 2007;9:114–20. 11. Bischof D, Graves K, Genoni M, Zollinger A, Hofer C. Fatal disconnection of a ventricular assist device in an out-of-hospital setting. Emerg Med J 2012;29:247–8. 12. Brouwers C, Denollet J, Jonge N, Caliskan K, Kealy J, Pedersen S. Patient-reported outcomes in left ventricular assist device therapy: a systematic review and recommendations for clinical research and practice. Circ Heart Fail 2011;4:714–23. 13. MacIver J, Ross H. Advances in mechanical circulatory support: quality of life and left ventricular assist device support. Circulation 2012;126:866–74. 14. Schima H, Stoiber M, Schlo¨glhofer T, Hartner Z, Haberl T, Zimpfer D. Repair of left ventricular assist device driveline damage directly at the transcutaneous exit site. Artif Organs 2014;38:422–5. 15. Douglas VC, Josephson A. Altered mental status. Continuum 2011; 17:967–83. 16. Day SW, McDaniel JC. PIV measurements of flow in a centrifugal blood pump: time-varying flow. J Biomech Eng 2005;127:254–63. 17. Brouwers C, Denollet J, Caliskan K, et al. health status, anxiety and depression in heart failure patients after heart transplantation versus left ventricular assist device implantation. J Heart Lung Transplant 2013;32(Suppl.):S195–6. 18. Tigges-Limmer K, Scho¨nbrodt M, Roefe D, Arusoglu L, Morshuis M, Gummert JF. Suicide after ventricular assist device implantation. J Heart Lung Transplant 2010;29:692–4. 19. Akhter S, Marcangelo M, Valeroso T, Singh A, Rich J, Jeevanandam V. Psychosocial risk as a predictor of survival following LVAD implant. J Heart Lung Transplant 2013; 32(Suppl.):S132.
Reconnection of a Transected LVAD 20. Orathi S, Anthony G, Henning P, et al. Management issues during HeartWare left ventricular assist device implantation and the role of transesophageal echocardiography. Ann Cardiac Anesth 2013; 16:263. 21. Bennett MK, Roberts CA, Dordunoo D, et al. Ideal methodology to assess systemic blood pressure in patients with continuous-flow left ventricular assist devices. J Heart Lung Transplant 2010;29:593–4. 22. Lanier GM, Orlanes K, Hayashi Y, et al. Validity and reliability of a novel slow cuff deflation system for noninvasive blood pressure monitoring in patients with continuous flow left ventricular assist device. Circ Heart Fail 2013;6:1005–12.
551 23. Markham DW, Drazner MH. Measuring nonpulsatile blood pressure: say goodbye to the Doppler? Circ Heart Fail 2013;6: 879–80. 24. Slaughter M, Pagani F, Rogers J, et al. Clinical management of continuous-flow left ventricular assist devices in advanced heart failure. J Heart Lung Transplant 2010;29(Suppl.):S1–39. 25. Nakahara S, Chien C, Gelow J, et al. Advances in arrhythmia and electrophysiology: ventricular arrhythmias after left ventricular assist device. Circulation Arrhythm Electrophysiol 2013;6:648–54. 26. Kirklin JK, Naftel DC. FDA Executive Summary: HeartWare Ventricular Assist System. April 25, 2012.
http://dx.doi.org/10.1016/j.jemermed.2014.07.028
Selected Topics: Critical Care EMERGENT RECONNECTION OF A TRANSECTED LEFT VENTRICULAR ASSIST DEVICE DRIVELINE Efrain Israel Cubillo IV, MD, Ricardo A. Weis, MD, and Harish Ramakrishna, MD, FASE Division of Cardiovascular and Thoracic Anesthesiology, The Mayo Clinic, Phoenix, Arizona Reprint Address: Harish Ramakrishna, MD, FASE, Division of Cardiovascular and Thoracic Anesthesiology, The Mayo Clinic Phoenix, 5777 East Mayo Boulevard, Phoenix, AZ 85054
, Keywords—mechanical circulatory systems; left ventricular assist device; driveline transection; driveline rewiring; HeartWare
, Abstract—Background: Recent clinical advances with new mechanical circulatory systems have led to additional strategies in the treatment of end-stage heart failure. The third-generation HeartWare Left Ventricular Device (LVAD) System utilizes a blood pump and a driveline (cable) that exits the patient’s skin connecting the implanted pump to an externally worn controller. We report a rare case of a HeartWare LVAD driveline rewiring after accidental (presumed) transection of the driveline system. Case Report: A 67-year-old male with a medical history of ischemic cardiomyopathy status post HeartWare LVAD implantation presented to the emergency department (ED) after acute LVAD failure. On the morning of presentation, he attempted to cut the paper tape off of his adult diaper with scissors and accidentally (presumed) and unwitnessed severed the driveline system. The patient immediately went into cardiac arrest and was transported to a regional medical center. On arrival, he exhibited no appreciable vital signs and was subsequently intubated, vascular access was placed, and inotropic support initiated. The emergency physician individually stripped and reconnected the color-coded driveline wires using multiple hemostats, electrical tape, and cardboard, which resulted in regeneration of positive LVAD flows. Why Should an Emergency Physician Be Aware of This?: VAD patients will present in extremis typically to the ED with manifestations of pump dysfunction ranging from diminished flows needing fluid management or pump adjustments to full pump failure manifesting as cardiogenic shock, needing rapid resuscitation and transfer to a cardiothoracic surgical unit with on-site VAD-perfusion specialists. Ó 2014 Elsevier Inc.
INTRODUCTION While the population of patients with congestive heart failure has risen to > 5 million Americans and resulted in 282,000 annual deaths, the available transplantation population has remained stagnant at approximately 2000 donors per year (1,2). Recent advances and implementation of left ventricular assist devices (LVADs) have dramatically changed the lifestyles of patients with chronic heart failure. VAD implantation has grown from 280 implants per year in 2007 to 1450 implants in 2011 (3). As a result, > 5500 Americans are living with VADs and many more are expected, given the aging of the ‘‘baby-boomer’’ generation (3,4). The LVAD system in general utilizes a blood pump and a percutaneous driveline consisting of an electrical connection to the external controller and a pneumatic conduit that allows atmospheric venting or emergent pneumatic hand pumping (5,6). The Heartware LVAD is one of the new-generation, axial flow devices that is designed for left ventricular support. Its main advantage compared to its predecessors is its smaller size and compact design, which does not require the creation of a preperitoneal pocket during implantation. Its driveline is significantly thinner than the previous generation of
RECEIVED: 13 March 2014; FINAL SUBMISSION RECEIVED: 24 June 2014; ACCEPTED: 1 July 2014 546
Reconnection of a Transected LVAD
547
to report a fatal VAD malfunction of an axial flow Heartware assist device (11). CASE REPORT
Figure 1. Animated view of HeartWare left ventricular assist device basic components/function.
devices. Constructed with conductor wires used in pacemakers, the driveline of the HeartWare LVAD (Figure 1) maintains durability through a protective woven polyester outer sheath (7). Although constructed with a protective outer sheath and fatigue-resistant cables, the driveline is thin (4.2 mm) and flexible, therefore, a primary source of damage (3,8). The multilayer assembly separates individual conductors, thereby theoretically avoiding abrasion. In addition, due to its percutaneous location, drivelines are significant sources of infection (9,10). Indeed, the driveline of VADs is considered by many to be the ‘‘Achilles heel’’ of these devices. The HeartWare Ventricular Assist System implanted in the patient described in our case report obtained U.S. market approval in November 2012 from the U.S. Food and Drug Administration as a bridge-to-transplantation therapy for patients with advanced-stage heart failure. The HeartWare System has been commercially available in other global markets, including Europe and Australia, since 2009. To date, nearly 4000 patients worldwide have been treated with the HeartWare Ventricular Assist System (5,6). The technical improvements and proven success of implantable VADs have made it a reasonable treatment option in these patients as a bridge to cardiac transplantation, bridge to recovery, or destination therapy. We report a rare (so far unreported in the United States) case of a patient fatality after accidental (presumed) Heartware LVAD driveline transection, which was followed by emergency department (ED) attempts of rapid driveline repair. The future of LVAD technology and the psychological aspects surrounding this event are also discussed. To date, there are no reports of successful LVAD rewiring after driveline transection. In 2010, the European literature described a fatal VAD malfunction in Germany involving disconnection of a right atrial cannula in a Berlin Heart BIVAD. We believe ours is the first case
A 67-year-old male with a medical history of ischemic cardiomyopathy status post HeartWare LVAD implantation as destination therapy 1½ years earlier presented to the ED after acute LVAD failure. On the morning of presentation, the patient was trying to use the bathroom. Sitting on his commode, he attempted to cut the paper tape off of his adult diaper with scissors and accidentally (presumed) and unwitnessed, severed the Heartware LVAD driveline system. Upon disconnection from the LVAD, the systems alarms instantly went off and the patient immediately went into cardiac arrest. Soon thereafter, his wife started chest compressions, which were continued until emergency medical services (EMS) arrived. EMS reported that although he was minimally responsive on their arrival, the patient awoke briefly with initial compressions. What is not known is the length of the period of unwitnessed arrest after driveline transection. The patient was then transported to a regional medical center. On arrival, he had no appreciable vital signs and was subsequently intubated, vascular access was placed and inotropic support initiated. The emergency physician individually stripped and reconnected the color-coded driveline wires using multiple hemostats, electrical tape, and cardboard (Figures 2 and 3A D), which resulted in regeneration of positive LVAD flows. Once the patient was stable, he was emergently transferred to our institution for further definitive management. On arrival, the patient’s baseline rhythm was ventricular tachycardia
Figure 2. Two-view right forearm of patient with six hemostatic clamps around left ventricular assist device (LVAD) driveline with adjacent LVAD controller.
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Figure 3. (A) Superficial view of patient’s right forearm with multiple hemostatic clamps and electrical tape surrounding left ventricular assist device (LVAD) driveline connection. Entire apparatus held by adhesive tape surrounding lateral cardboard. (B) Closer view of hemostatic clamps/electrical tape connecting LVAD driveline. (C) View demonstrating electrical wiring of LVAD driveline with hemostatic clamps providing continuity. (D) Hemostatic clamps connecting appropriate LVAD driveline (cardboard underneath hemostats/driveline wires).
at 175 beats/min with a mean arterial pressure of 40 mm Hg with LVAD flows of 4 L/min. He immediately was cardioverted (200 J), which successfully returned him to sinus rhythm. The patient was placed on dobutamine, epinephrine, norepinephrine, and vasopressin infusions. Urgent transesophageal echocardiogram was performed, which showed flow through the aortic cannula, right ventricular function was mild to moderately depressed, and no pericardial effusion was noted. The patient underwent right heart catheterization with Swan Ganz catheter placement for further invasive hemodynamic monitoring. Results demonstrated a cardiac output of 5.5 L/min and systemic vascular resistance of 814 dyn/cm/s. Pertinent findings on physical examination, included sluggishly reactive pupils, gag reflex present, no withdrawal to pain, and cool distal extremities. On neurological evaluation after 24 h off sedation, the patient maintained brainstem reflexes, although he did not withdraw to pain or have any spontaneous movements. Care was withdrawn on day 7 due to the patients’ poor neurological prognosis. DISCUSSION Over the years, data have continued to accumulate testifying to the broad success that VADs have brought to the definitive management of end-stage heart failure (3,12). However, success and applicability of this therapy are largely limited by high complication rates
associated with these devices. Overall, the most frequent complications include bleeding (especially gastrointestinal), cerebral, and peripheral thromboembolic complications, renal failure, right ventricular failure, and life-threatening dysrhythmias. They can be an entry point for infections (between 14% and 50%) (10). It is not just the driveline, but the entire VAD that is susceptible to infection, including the surgical site, device pocket, driveline, valves, and conduits (10,12,13). Cable lesions and even electrical failures due to material fatigue can occur. It must be appreciated that most VAD patients lead very mobile lives in the community, attached to technology that may not be able to necessarily withstand abuse. Although the incidence of driveline reconnection after disruption of the electrical circuit is a very rare event, Schima et al. reported a quick stabilization method for a patient who survived with a fracture of the outer sheath of a HeartWare HVAD driveline (14). In their report, the metal strands and the electrical functionality were not affected, contrary to our case, where the electrical circuitry was affected with catastrophic results (14). The typical VAD patient has little or no native cardiovascular reserve and is completely pump dependent. Because of this, and the characteristic continuous flow of the HeartWare LVAD, these patients usually have minimal to no palpable pulse, which can be disconcerting to patients, families, and health care providers. Our patient was diabetic, medications also included citalopram, Vicodin, and clonidine. These drugs, as
Reconnection of a Transected LVAD
well as hypoglycemia or hyperglycemia, could have caused mental confusion (15). In addition, fluctuations in VAD flow in every patient create near-constant variations in cardiac output, which could affect brain perfusion from systemic hypoperfusion (16). These variables could affect the patient’s mental status and may have contributed to the event. The ‘‘accidental’’ driveline disruption in our case warranted further investigation with respect to the psychological aspects surrounding this event. Reports from the patients’ family included an intact family support system and no evidence of depression or suicidal intention, although no documented regular psychological followup. Some studies have found a considerable group of LVAD patients to be suffering from a depressive or adjustment disorder (21% and 37% to 50%, respectively) (17). Tigges-Limmer et al. reported a 69-year-old depressed patient who committed suicide by disconnecting the driveline of his LVAD almost 3 years after implantation (18). Psychosocial issues are being increasingly reported in the surgical literature, as the article by Akhter et al. demonstrates (19). The crucial issue, however, seems to be driveline related. The VAD industry has recognized this and technology advances are in the pipeline. The ideal VAD should have a 0% incidence of driveline complications specifically related to infection/driveline disruption, and wireless technologies are sure to be introduced in the not-too-distant future (3,20). In addition, to optimize the management of an increasingly growing population of LVAD patients, direct participation of psychologists, psychiatrists, palliative care specialists, a concise plan of care for anticipated devicerelated complications and a discussion about the longterm financial burden on patients, families, and caregivers is recommended. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS? As the duration of LVAD support is increasing, these patients present numerous challenges to noncardiac care takers, including first responders (EMS), emergency medicine physicians, nurses, pharmacists, and society in general, who are not familiar with the management of these patients who need expert subspecialty care. VAD patients will present in extremis typically to the ED with manifestations of pump dysfunction ranging from diminished flows needing fluid management or pump adjustments to full pump failure manifesting as cardiogenic shock, needing rapid resuscitation and transfer to a cardiothoracic surgical unit with on-site VAD-perfusion specialists. Under resting conditions, all continuous-flow LVAD patients exhibit a loss of pulsatility in the arterial system,
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leading to clinically significant difficulties in noninvasive blood pressure measurement using the standard methods, such as an automated cuff system. This phenomenon can be better understood when one recognizes that arterial pulsatility in LVAD patients is clearly correlated with aortic valve opening. LVAD patient’s exhibit highly variable levels of aortic valve function, ranging from no aortic valve function that manifests in a complete lack of all pulsatility (which can be displayed by the device as a pulsatility index) to intermittent or greater aortic valve function that will produce varying degrees of pulsatility that render noninvasive cuff methods easier in some patients. Invasive arterial monitoring via arterial line is therefore the gold standard, but not always feasible in the outpatient or ED setting. The use of Doppler to measure blood pressure in these patients has been advocated by many LVAD centers (21). There are problems with Doppler, however, it is operator dependent and requires expertise and training. In addition, it is unclear whether one is measuring the mean arterial pressure (MAP) or the systolic blood pressure (SBP). Recently, Lanier et al., in a study investigating blood pressure measurement in LVAD patients, found that there were significant limitations with the Doppler method. In nonpulsatile LVAD patients, Doppler measurement underestimated SBP by approximately 4 mm Hg and overestimated MAP by approximately 9 mm Hg, which would suggest that it more reflected the SBP compared to the MAP, this limitation was more evident when the pulse pressure was increased (when the SBP and MAP are more separated) (22). This has important clinical implications in that confusing SBP and MAP measurements might lead to higher BP medication titration, leading to clinical hypotension. Markham et al., in a recent editorial, suggested that there may be better options, such as the Terumo hybrid design blood pressure monitor, where the cuff deflation speed can be programmed to be much slower for patients with weak or impalpable pulses (23). Slaughter et al., in their guidelines, suggest maintaining MAP in the 70 to 80 mm Hg range for LVAD patients, taking care to avoid an MAP > 90 mm Hg (increased afterload results in LVAD pump output reductions of varying severity) (24). Pulse oximetry, if obtainable, may be unreliable due to diminished pulse pressure. As an index of perfusion, pulse oximetry is another critically important tool in these patients, which is again, limited by non-pulsatility. The best practice is to attempt multiple sites of monitoring (ear lobe, nose, forehead) if one site fails. Cerebral oximetry can be utilized for assessing hemodynamic conditions when more invasive monitoring is not available. To assess perfusion status basic clinical assessments are used, such as the use of mental status, skin color, temperature, auscultation of the LVAD motor, bedside echocardiography, and assessing the machine alarms for low flow indicators.
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The emergency physician may be challenged with managing dysrhythmias in LVAD patients. Ventricular arrhythmias (VA) have been reported to occur in 22% to 59% of LVAD recipients (25). The majority of LVAD patients have automatic implantable cardioverter defibrillators (AICDs) as a standard of care in most LVAD centers. In patients with AICDs, defibrillation can be safely attempted using the existing device and standard electrophysiologic guidance. The presentation of VA in patients with LVADs is variable. Some patients with LVADs can experience right heart failure, hemodynamic deterioration, ICD shocks, and even cardiac arrest with VA caused by impaired right ventricular filling leading to inadequate LVAD flows. Similar to other clinical settings, b-adrenergic antagonists are used as first-line treatment for patients with VA after LVAD. For those who are refractory to b-adrenergic antagonists, intravenous amiodarone and lidocaine can be used acutely. Sotalol can be used as an alternative if amiodarone is not tolerated or there are concerns about toxicities. Finally, close attention to potassium and magnesium levels and avoidance of QT prolonging medications should be considered. In the circumstance that the patient is refractory to pharmacological intervention and becomes unconscious, unresponsive to stimuli, and unobtainable MAP with pump malfunction, cardiopulmonary resuscitation (CPR) should be performed per cardiac arrest protocol. External pads/paddles can be placed in the standard positions with the caveat that nothing should be placed on the device or drivelines. Before initiating CPR, it is vital to assess the audible sounds of the LVAD. If the whirling sound of the LVAD is present, CPR is contraindicated as this may result in cannula dislodgment of the device and death (24,25). Battery issues in LVAD patients are typically rare. The Heartware LVAD in our patient contained two batteries (lithium ion), with each battery providing 4 to 6 h when fully charged, with usage that depends on pump power consumption and the number of charge and discharge cycles. Each patient typically will possess a battery charger that charges 4 batteries at a time. Battery icons are clearly displayed on the device monitor screen with percentages of charge remaining, with an alarm that will sound when < 24% of the battery capacity exists. Most patients travel with two batteries in their patient pack, which holds the Heartware controller and the two batteries. They also have an AC adaptor for use with a wall outlet and a DC adaptor, which can be used for charging the batteries in a car outlet (26). In our case report, the emergency physician should be commended for the rapid troubleshooting and attempted rewiring of the transected driveline. In summary, we aim to reinforce the fact that the driveline continues to be a serious source of VAD morbidity and mortality. Even with rapid resuscitation, as was the
E. I. Cubillo IV et al.
case in our patient, these patients are completely device dependent, with no underlying cardiovascular reserve. Newer generations of this technology are sure to overcome this problem, but until then all clinicians should be aware of the critical importance and vulnerability of the VAD driveline.
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Reconnection of a Transected LVAD 20. Orathi S, Anthony G, Henning P, et al. Management issues during HeartWare left ventricular assist device implantation and the role of transesophageal echocardiography. Ann Cardiac Anesth 2013; 16:263. 21. Bennett MK, Roberts CA, Dordunoo D, et al. Ideal methodology to assess systemic blood pressure in patients with continuous-flow left ventricular assist devices. J Heart Lung Transplant 2010;29:593–4. 22. Lanier GM, Orlanes K, Hayashi Y, et al. Validity and reliability of a novel slow cuff deflation system for noninvasive blood pressure monitoring in patients with continuous flow left ventricular assist device. Circ Heart Fail 2013;6:1005–12.
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