Improved Results for Postcardiotomy Cardiogenic Shock With the Use of Implantable Left Ventricular Assist Devices

Improved Results for Postcardiotomy Cardiogenic Shock With the Use of Implantable Left Ventricular Assist Devices Joseph J. DeRose, Jr, MD, Juan P. Umana, MD, Michael Argenziano, MD, Katharine A. Catanese, MSN, Howard R. Levin, MD, Benjamin C. Sun, MD, Eric A. Rose, MD, and Mehmet C. Oz, MD Divisions of Cardiothoracic Surgery and Circulatory Physiology, Columbia-Presbyterian Medical Center, New York, New York

Background. Over the past decade, the use of mechanical circulatory support in patients with postcardiotomy cardiogenic shock has resulted in hospital discharge rates of 25% to 40%. In an attempt to improve patient survival, we initiated a program of early insertion of an implantable Thermocardiosystems Incorporated Heartmate left ventricular assist device in patients who have circulatory failure after having undergone high-risk cardiac operations. Methods. Between April 1993 and February 1997, 12 patients underwent insertion of an implantable left ventricular assist device for postcardiotomy cardiogenic shock after coronary artery bypass grafting. Indications for insertion included postoperative cardiogenic shock (7 patients), postoperative cardiac arrest (3 patients), and failure to wean from cardiopulmonary bypass (2 patients). Results. The median time to device insertion was 3.5

days. The mean duration of left ventricular assist device support was 103 6 19 days (range, 2 to 225 days). Nine of 11 patients (82%) survived to undergo either transplantation (8 patients) or explantation (1 patient), with successful hospital discharge of all 9 patients. The major complication was device-related infection (42%). A single thromboembolism occurred in a patient with an infection. Conclusions. Long-term outcome after postcardiotomy cardiogenic shock is improved substantially with the use of an implantable left ventricular assist device early in the postoperative course. Access to such a device is an important consideration before undertaking a high-risk cardiac operation, and early implantation of the device is a critical factor in ensuring long-term survival.

P

pulmonary hypertension, and the need for biventricular support all are more prevalent in this critically ill cohort of patients compared with other populations who receive mechanical circulatory support. Preexisting depressed myocardial function, recent or intraoperative myocardial infarction, and myocardial necrosis also negatively affect survival in patients who receive ventricular assist devices for PCCS. Between August 1990 and February 1997, 84 patients underwent implantation of the Thermocardiosystems Incorporated (TCI; Woburn, MA) Heartmate left ventricular assist device (LVAD) at our institution, with an overall survival rate to transplantation or explanation of 79% [15]. The acceptably low thromboembolism rate of 0.015 events per patient-month of support [15, 16] and the facilitation of early progressive rehabilitation [17] has made implantable devices an appealing option as a bridge to both transplantation and myocardial recovery. In an attempt to improve the relatively poor survival of patients with PCCS, we initiated a program of early TCI LVAD implantation in patients who have circulatory failure after having undergone high-risk coronary artery bypass grafting (CABG). Herein we report on 12 patients with PCCS who were supported with the TCI LVAD.

ostcardiotomy cardiogenic shock (PCCS) occurs in approximately 2% to 6% of patients who undergo myocardial revascularization or valvular heart operations [1]. Early institution of intraaortic balloon counterpulsation (IABP) together with aggressive inotropic support allows successful weaning from cardiopulmonary bypass of 75% to 85% of patients, with a hospital survival rate of See also page 1764.

50% to 55% [1–5]. In the remaining patients who are unresponsive to IABP and inotropic support, various forms of mechanical circulatory assistance have been used, with hospital discharge rates ranging from 25% to 50% [4, 6 –14]. The relatively poor results of mechanical support in this setting are related to the late institution of support and a subsequently high incidence of complications. Renal failure, coagulopathy, bleeding, right heart failure, Accepted for publication July 3, 1997. Address reprint requests to Dr DeRose, c/o Dr Oz, Division of Cardiothoracic Surgery, Milstein Hospital Bldg, 177 Fort Washington Ave, New York, NY 10032 (e-mail: [email protected]).

© 1997 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

(Ann Thorac Surg 1997;64:1757– 63) © 1997 by The Society of Thoracic Surgeons

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Table 1. Primary Operation, Initial Mechanical Support, and Indication for Implantable Left Ventricular Assist Device Insertion in 12 Patients With Postcardiotomy Cardiogenic Shock Patient No.

Age (y)

Initial Operation

1 2 3 4 5 6 7

51 47 62 48 58 62 47

Elective CABG Urgent CABG after failed PTCA Reoperative CABG Elective CABG Elective CABG/ICD insertion Elective CABG Elective CABG

IABP ABIOMED LVAD IABP IABP IABP IABP None

8 9 10 11 12

61 61 52 56 52

Reoperative CABG Elective CABG Elective CABG Elective CABG Elective CABG

IABP, BioMedicus LVAD None IABP, ABIOMED LVAD IABP IABP

Pre-LVAD Mechanical Support

Indication for LVAD Implantation Postoperative cardiogenic shock Failure to wean from cardiopulmonary bypass Postoperative cardiac arrest Postoperative cardiogenic shock Postoperative cardiogenic shock Postoperative cardiogenic shock Postoperative cardiogenic shock, intractable ventricular arrhythmias Failure to wean from cardiopulmonary bypass Postoperative cardiogenic shock Postoperative cardiac arrest Postoperative cardiac arrest Postoperative cardiogenic shock

CABG 5 coronary artery bypass grafting; IABP 5 intraaortic balloon counterpulsation; ICD 5 implantable cardioverter-defibrillator; left ventricular assist device; PTCA 5 percutaneous transluminal coronary angioplasty.

Patients and Methods Patients Between April 1993 and February 1997, 12 patients underwent TCI LVAD implantation for PCCS. Postcardiotomy cardiogenic shock was defined as either (1) the inability to wean from cardiopulmonary bypass despite IABP and maximal inotropic support, or (2) early postoperative ventricular failure associated with a pulmonary capillary wedge pressure of greater than 20 mm Hg and either a cardiac index of less than 2.0 L z min21 z m22 or a systolic blood pressure of less than 80 mm Hg despite maximal inotropic support. Eleven of the patients were men, with a mean age of 55 6 6 years (range, 47 to 62 years). Nine of the patients underwent high-risk elective CABG, 2 underwent reoperative CABG, and 1 underwent emergency CABG after failed percutaneous transluminal coronary angioplasty (Table 1). Six of the patients underwent their initial operation at our institution and the other 6 were transferred from referral hospitals for further management after temporary stabilization. Indications for mechanical circulatory support included failure to wean from cardiopulmonary bypass, postoperative cardiogenic shock unresponsive to IABP and inotropic support, postoperative cardiovascular arrest, and postoperative cardiogenic shock in the setting of intractable malignant ventricular arrhythmias (Table 1). Seven patients had IABP placement, 3 patients were transferred from outside referral hospitals on short-term external LVAD support (1 ABIOMED [ABIOMED Cardiovascular, Danvers, MA], 1 BioMedicus [Medtronic Biomedicus, Inc, Eden Prairie, MN]), and 2 patients had no additional mechanical circulatory support before TCI LVAD implantation. The median period from CABG to TCI LVAD implantation was 3.5 days, and 11 patients (92%) were intubated for 3.1 6 2.0 days before implantable LVAD insertion. Hemodynamic indices before LVAD insertion included a

LVAD 5

systolic blood pressure of 92 6 20 mm Hg, a left ventricular ejection fraction of 0.16 6 0.06, a cardiac index of 1.7 6 0.5 L z min21 z m22, and a central venous pressure of 17 6 3 mm Hg (Table 2). Preoperative laboratory values were significant for elevations in prothrombin time (9 patients receiving heparin), serum creatinine, serum aspartate transaminase/alanine transaminase, and white blood cell count (Table 3). Of the 12 LVADs implanted, 8 were pneumatic and 4 were vented electric devices.

Implantation Technique A properitoneal pocket was created for the device in the left upper quadrant, before heparinization if possible. The patients then were heparinized and cardiopulmonary bypass was initiated through standard right atrial and aortic cannulation. If an external short-term LVAD was in place, care was taken to bleed out the inflow cannula before removal to reduce the risk of embolism. We used the serine protease inhibitor aprotinin (Miles Inc, West Haven, CT) in almost all cases to reduce bleeding and subsequent right heart failure [18]. A vent was placed through the left ventricular apex and device implantation was performed without cardioplegia or aor-

Table 2. Hemodynamic Indices Before and 24 Hours After Left Ventricular Assist Device Implantation Hemodynamic Index Systolic blood pressure (mm Hg) Central venous pressure (mm Hg) Cardiac output (L/min) Left ventricular ejection fraction NS 5 not significant.

Before Operation

After Operation

p Value

92 6 20

127 6 20

0.001

17 6 3

15 6 3

NS

3.3 6 0.3 0.16 6 0.06

6.0 6 0.4 ...

0.0001 ...

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tic cross-clamping. The inflow cuff was sewn to the left ventricular apex, with care taken to place wide, pledgeted bites in the ventricular myocardium. This was particularly important in the setting of PCCS, because myocardial infarction and concomitant ventricular necrosis frequently were present. The outflow graft then was anastomosed to the right lateral portion of the ascending aorta. The device was activated and cardiopulmonary bypass was terminated with the patient in the steep Trendelenburg position to reduce the risk of air embolism. Inhaled nitric oxide was used in the setting of pulmonary hypertension and arginine vasopressin (Pitressin) was useful in patients with catecholamineresistant vasodilatory hypotension.

Statistics All results are recorded as the mean plus or minus the standard deviation. Continuous variables were analyzed by the paired Student’s t-test. Fisher’s exact test for 2 3 2 tables was used for categorical variables. Analysis was considered significant at a p value of 0.05 or less.

Results Twenty-four hours after LVAD implantation, improvements were noticed in systolic blood pressure, central venous pressure, and cardiac output (Table 2). Prothrombin time, aspartate transaminase/alanine transaminase, and serum creatinine likewise showed trends toward normalization at the time of intensive care unit discharge, although none of these improvements reached statistical significance (Table 3). Patients were intubated after operation for a mean of 6.6 6 6.2 days (range, 1 to 21 days), and they had a mean intensive care unit stay of 12.6 6 5.8 days (range, 5 to 24 days). The mean duration of LVAD support was 103 6 62 days (range, 2 to 225 days). Nine patients underwent successful transplantation and 1 patient underwent explantation, for an overall survival-to-discharge rate of 82%. The patient who underwent explantation required device Table 3. Laboratory Values Measured Immediately Before Operation and After Left Ventricular Assist Device Insertion at the Time of Intensive Care Unit Dischargea,b

Laboratory Value Prothrombin time (s) (10.5–12.9) Creatinine (mg/dL) (0.6 –1.5) Aspartate transaminase (U/L) (1–31) Alanine transaminase (U/L) (1–31) White blood cell count (4,500 –11,000) a

All p values were not significant. normal ranges.

Before Operation

Intensive Care Unit Discharge

14.1 6 0.8

13.3 6 1.5

1.4 6 0.6

1.2 6 0.8

152 6 147

51 6 71

89 6 126

38 6 21

13,780 6 420 b

12,182 6 585

Numbers in parentheses are

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Table 4. Complications Among Patients Who Underwent Left Ventricular Assist Device Insertion for Postcardiotomy Cardiogenic Shock Compared With Patients Who Underwent Left Ventricular Assist Device Insertion for All Other Indicationsa

Complication Device-related thromboembolism Right heart failure requiring RVAD LVAD device infection LVAD driveline or pocket infection

Postcardiotomy Cardiogenic Shockb

Otherb

1/12 (8)c 1/12 (8)

4/73 (5)d 5/73 (7)

2/12 (17) 3/12 (25)

7/73 (10) 19/73 (26)

a

b All p values were not significant. Data are number of complications per total number of patients in group, with percentages in parenthec Overall incidence, 0.025 events per patient-month of support. ses. d Overall incidence, 0.0132 events per patient-month of support.

LVAD 5 left ventricular assist device; device.

RVAD 5 right ventricular assist

removal for device endocarditis after 4 months of support. This patient experienced malignant ventricular arrhythmias before device insertion in the setting of a depressed ejection fraction. During ventricular support, the patient’s arrhythmias were managed well. At the time of device removal, acute measures of cardiac function had normalized substantially. It was elected to forego transplantation for explantation. This patient has recovered to New York Heart Association class II heart failure 18 months after device removal and has an ejection fraction of 0.50 by multigated angiography. The 9 patients who underwent transplantation remain alive and well through a mean follow-up period of 20 6 13 months. There was 1 death in a patient who was transferred from an outside hospital in cardiogenic shock on IABP support after reoperative CABG. This patient experienced cardiac arrest on transport to the operating room for LVAD placement. After LVAD implantation, right ventricular failure necessitated the placement of an ABIOMED right ventricular assist device (ABIOMED Cardiovascular, Danvers, MA). A profound coagulopathy subsequently developed and necessitated extracorporeal membrane oxygenation for severe hypoxia. At the family’s request, support was discontinued. A second death occurred in a patient who was transferred to our institution on external LVAD support after failure to wean from cardiopulmonary bypass. The patient was bridged successfully to an implantable device and was supported for 100 days. However, while in the hospital, the patient had an upper gastrointestinal hemorrhage resulting in hypoxia, decreased LVAD flows, and unresuscitatable cardiopulmonary arrest. Intraoperative right heart failure occurred in 2 patients. This was managed with a right ventricular assist device in 1 patient and with inhaled nitric oxide in the other. Complications included one episode of device-related thromboembolism, for an incidence of 0.025 events per patient-month of support (Table 4). This patient experienced a cerebrovascular accident on postoperative day 60 in the setting of an LVAD pocket infection and suspected

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LVAD endocarditis. A follow-up echocardiogram and cardiac catheterization revealed no evidence of native or device valvular vegetations. There were two device infections and three additional driveline infections. Other complications included one episode each of deep vein thrombosis, heparin-induced thrombocytopenia, and renal insufficiency secondary to aminoglycoside toxicity. There were 3 patients with sacral decubitus pressure ulcers and 1 patient who required a tracheostomy for prolonged mechanical ventilation. No patients required dialysis in the preoperative or postoperative period.

Comment The results of circulatory support in the urgent setting of PCCS have remained poor despite the use of numerous continuous centrifugal and pulsatile pneumatic devices. In a review of a combined registry experience of ventricular assist devices for postcardiotomy cardiogenic shock, Pae and colleagues [4] reported a 45% weaning rate and only a 24.6% discharge rate among 965 patients supported between 1985 and 1990. In this series, patients were supported for a mean of 4 days and both pneumatic and centrifugal devices were used. A model-based odds ratio predicted renal failure, biventricular failure, a neurologic event, bleeding, and infection to be negative predictors of successful weaning from circulatory support. Since this registry review, similar results have been obtained with temporary mechanical assistance after postcardiotomy circulatory failure [19, 20]. In the acute setting, the placement of a short-term external LVAD often proves lifesaving. These devices are inserted easily and can be used in centers that do not have long-term ventricular assist devices. Pneumatic pulsatile pumps such as the ABIOMED also might benefit community hospitals that do not have the technical manpower to operate centrifugal pumps or long-term implantable LVADs. Nonetheless, external LVADs provide only short-term support, during which time ventricular recovery may not be achieved. Emergency heart transplantation has been advocated by some in the setting of PCCS [21]. However, the high mortality rate of heart transplantation in the setting of preoperative intubation and end-organ failure wastes the precious resource of available donor hearts. Conversion to an implantable device after temporary stabilization with an IABP or an external LVAD allows for prolonged support times and improved survival compared with temporary support alone. However, the ability to perform early interventions is critical to ensuring this survival advantage. Among the 6 patients who underwent their initial operation at our institution, the median time to TCI LVAD insertion was 2.5 days. Intervention with an implantable device results in immediate unloading of the failing left ventricle and restoration of end-organ function. Furthermore, therapeutic strategies including the use of aprotinin, inhaled nitric oxide, and arginine vasopressin, have allowed us to avoid the negative survival determinants of bleeding, need for biventricular support, and renal insufficiency. Attention to

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technical detail also has been critical in ensuring success. In the setting of myocardial damage and recent myocardial infarction, the sewing ring must be secured to the left ventricular apex with large, pledgeted bites and a short inflow conduit. Our results with the use of mechanical circulatory assistance in the setting of PCCS are remarkably similar to those obtained in our overall experience (Table 4). Thromboembolism rates remained extremely low despite the use of little or no anticoagulation. Of the five thromboembolic events that occurred in our overall experience (0.0147 events per month of patient support), three occurred in the setting of device endocarditis. The one event in this series again occurred in a patient with a pocket infection and suspected device endocarditis. Device-related infections were slightly more prevalent in the PCCS cohort, but this difference failed to reach statistical significance. Finally, it is interesting to note that only 1 patient in this series required right ventricular assistance for right ventricular failure. This is in accordance with our overall LVAD experience, in which only 5 of 29 patients with right ventricular failure required a right ventricular assist device. The judicious use of inhaled nitric oxide has reduced further the need for right ventricular assist device placement over our past 40 LVAD insertions. Postcardiotomy cardiogenic shock remains a difficult problem with a high mortality rate and a significant morbidity rate. However, rapid and logical decisionmaking can result in improved survival. As opposed to the usual cohort of LVAD recipients, patients who experience PCCS usually are fairly healthy before operation, without chronic debilitation or end-organ injury. Therefore, early mechanical support results in rapid return of normal end-organ function. Return of cardiac function after mechanical unloading is well documented [22]. However, the ability to wean a patient off temporary assistance early (within 3 to 5 days) is dependent on both preoperative ventricular function and the degree of intraoperative myocardial injury. Decisions regarding conversion to an implantable device should be made within several days of temporary external LVAD assistance. In the present series, most patients received a device within 48 hours of temporary external LVAD placement or within 72 hours of initial cardiotomy. On the basis of our experience with mechanical circulatory assistance in the setting of PCCS, we have devised an algorithm for use in managing such patients (Fig 1). Patients with severely depressed ventricular function before operation who are considered to be at high risk for postoperative ventricular failure should have either permanently implantable or short-term mechanical support systems available at the time of operation. Mechanical prostheses should be avoided because the risk of infection would be increased greatly if mechanical assistance should become necessary. During operation, the decision to use temporary mechanical assistance usually is governed by the inability to maintain an appropriate cardiac output or systolic blood pressure despite maximal inotropic support and IABP placement. In the immediate

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Fig 1. Clinical algorithm for the management of postcardiotomy cardiogenic shock. (CPB 5 cardiopulmonary bypass; FCT, fct 5 function; IABP 5 intraaortic balloon counterpulsation; LV 5 left ventricular; LVAD 5 left ventricular assist device; MVO2 5 myocardial oxygen consumption; VAD 5 ventricular assist device.)

postoperative period, the need for mechanical support should be assessed by measures of end-organ function. Serious acidosis, a myocardial oxygen consumption of less than 50%, the onset of renal failure, hypoxia, and coagulopathy all are indicators that survival will be dependent on mechanical assistance. In patients with normal preoperative ventricular function, we advocate the placement of a short-term device with hopes of early ventricular recovery and subsequent device withdrawal. If the patient is considered to be an appropriate potential transplant candidate and is undergoing high-risk CABG with LVAD backup, the insertion of an implantable device at this time also is an option. At our institution, we recently adopted a policy of using TCI LVAD backup for high-risk patients, with plans for TCI insertion should circulatory failure ensue. This has allowed preoperative discussions with the patient and family about mechanical support, transplantation, and advanced medical directives. Once temporary mechanical LVAD assistance has been instituted, decisions regarding device weaning or conversion to an implantable LVAD must be made within 3 to 5 days. After this point, the risks and compli-

cations of external support begin to outweigh the advantages of improved hemodynamics, with diminishing beneficial returns. Attempts at device weaning should be guided by the technical success of the operation as well as by indicators of myocardial damage, including myocardial enzyme levels, electrocardiographic findings, and echocardiogram evaluation. If temporary device weaning appears unlikely, an assessment of the patient’s potential transplant candidacy should be undertaken. If the patient is anticipated to be a transplant candidate in the future, conversion to an implantable device should be undertaken. Once such a device is in place, aggressive rehabilitation and resumption of normal hemodynamics will allow the patient to resume preoperative functional levels quickly. With the wearable designs of implantable devices, patients even can be sent home while awaiting transplantation [23]. Finally, patients who are placed on temporary external LVADs who are not transplant candidates and cannot be weaned in the early postoperative period have few options. Discussions with the family should be initiated and device withdrawal may be necessary in this setting. It is hoped that in the future, implantable LVADs can be

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offered to such patients as destination therapy for endstage heart disease. Trials to answer this question are ongoing, and such treatments soon may be possible for those patients who have no other alternatives [24]. Long-term outcome after PCCS is improved substantially with the use of an implantable LVAD early in the postoperative course. Implantable LVAD support should be considered as an initial treatment option in patients who are unresponsive to IABP and ionotropic support when ventricular recovery is not expected. The technical challenges of TCI device insertion are a major limitation to its use in the emergency setting, leading us to advise short-term device insertion for acute stabilization. In conclusion, either the presence of an implantable device at the operating facility or access to a center to which a patient can be referred rapidly is an important consideration before undertaking high-risk CABG.

References 1. Pennington DG, Swartz M, Codd JE, Merjavy JP, Kaiser GC. Intra-aortic balloon pumping in cardiac surgical patients: a nine year experience. Ann Thorac Surg 1983;36:125–31. 2. McEnany TM, Kay HR, Buckley MJ, et al. Clinical experience with intra-aortic balloon pump support in 782 patients. Circulation 1978;58:1124–32. 3. Norman JC, Cooley DA, Igo SR, et al. Prognostic indices for survival during postcardiotomy intra-aortic balloon pumping. J Thorac Cardiovasc Surg 1977;74:709–20. 4. Pae WE Jr, Miller CA, Matthews Y, Pierce WS. Ventricular assist devices for postcardiotomy cardiogenic shock. A combined registry experience. J Thorac Cardiovasc Surg 1992; 104:541–53. 5. Downing TP, Miller DC, Stofer R, Shumway NE. Use of the intra-aortic balloon pump after valve replacement. J Thorac Cardiovasc Surg 1986;92:210–7. 6. Pae WE, Pierce WS, Pennock JL, Campbell DB, Waldenhausen JA. Long-term results of ventricular assist pumping in postcardiotomy cardiogenic shock. J Thorac Cardiovasc Surg 1987;93:434– 41. 7. Pennington DG, Samuels LD, Williams G, et al. Experience with the Pierce-Donachy ventricular assist device in postcardiotomy patients with cardiogenic shock. World J Surg 1985; 9:37– 46. 8. Curtis JJ, Walls JT, Schmaltz RA, et al. Improving clinical outcome with centrifugal mechanical assist for postcardiotomy ventricular failure. Artif Organs 1995;19:761–5.

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9. Curtis JJ, Walls JT, Schmaltz RA, et al. Use of centrifugal pumps for postcardiotomy ventricular failure: technique and anticoagulation. Ann Thorac Surg 1996;61:296 –300. 10. Korfer R, El-Banayosy A, Poisval H, et al. Mechanical circulatory support with the Thoratec assist device in patients with postcardiotomy cardiogenic shock. Ann Thorac Surg 1996;61:314– 6. 11. Noon GP, Ball JW, Papaconstantinou HT. Clinical experience with BioMedicus centrifugal ventricular support in 172 patients. Artif Organs 1995;19:756– 60. 12. Muehrcke DD, McCarthy PM, Stewart RW, et al. Extracorporeal membrane oxygenation for postcardiotomy cardiogenic shock. Ann Thorac Surg 1996;61:684–91. 13. Murakami T, Kino K, Irie H, et al. Results of circulatory support for postoperative cardiogenic shock. Artif Organs 1994;18:691–7. 14. Peterzen B, Lonn U, Babic A, et al. Postoperative management of patients with Hemopump support after coronary artery bypass grafting. Ann Thorac Surg 1996;62:495–500. 15. Oz MC, Argenziano M, Catanese KA, et al. Bridge experience with long-term implantable left ventricular assist devices: are they an alternative to transplantation? Circulation 1997;95:1844 –52. 16. Slater JP, Rose EA, Levin HR, et al. Low thromboembolic risk without anticoagulation using advanced-design left ventricular assist devices. Ann Thorac Surg 1996;62:1321– 8. 17. Morrone TM, Buck LA, Catanese KA, et al. Early progressive mobilization of left ventricular assist device patients is safe and optimizes recovery prior to cardiac transplant. J Heart Lung Transplant 1996;15:423–9. 18. Goldstein DJ, Seldomridge JA, Chen JM, et al. Use of aprotinin in LVAD recipients reduces blood loss, blood requirement, and perioperative mortality. Ann Thorac Surg 1995;59:1063– 68. 19. Jett GK. ABIOMED BVS 5000: experience and potential advantages. Ann Thorac Surg 1996;61:301– 4. 20. Noon GP, Ball JW Jr, Papaconstantinou HT. Clinical experience with Biomedicus centrifugal ventricular support in 172 patients. Artif Organs 1995;19:756– 60. 21. Vijayanagar RR, Chan GL, Weinstein SS. Urgent heart transplantation in patients with previous sternotomies. Cardiovasc Surg 1995;3:331–5. 22. Bavaria JE, Furukawa S, Kreiner G, Gupta KB, Streicher J, Edmunds LH Jr. Effect of circulatory assist devices on stunned myocardium. Ann Thorac Surg 1990;49:123– 8. 23. Catanese KA, Goldstein DJ, Williams DL, et al. Outpatient left ventricular assist device support: a destination rather than a bridge. Ann Thorac Surg 1996;62:646–53. 24. Rose EA, Goldstein DJ. Wearable long-term mechanical support for patients with end-stage heart disease: a tenable goal. Ann Thorac Surg 1996;61:399 – 402.

INVITED COMMENTARY Great progress has been made in the development and clinical use of ventricular assist devices (VADs). The ability of VADs both to support the circulation in the potentially reversible situation and to provide a bridge to orthotopic transplantation is unquestioned. The clinical outcomes when the devices are used as a bridge to transplantation have been no less than spectacular. However, the results of VADs in patients with postcardiotomy cardiogenic shock have been disappointing. What this report underscores, perhaps more than is apparent, is that the selection of patients for support is critical to success. Previous reports have indicated that rates of subse© 1997 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

quent transplantation and ultimate hospital discharge in device-dependent postcardiotomy patients who are transplant candidates are nearly identical to those obtained when VADs are used as a standard bridge to transplantation. The authors’ excellent clinical results confirm these findings in a very select group of patients with postcardiotomy cardiogenic shock. The authors also present an algorithm with which to manage such patients that should be useful in any program that performs cardiac surgical procedures. The widespread availability of short-term mechanical support systems approved by the Food and Drug Administration should allow for timely (early) intervention 0003-4975/97/$17.00 PII S0003-4975(97)01108-9