Experience with the Pierce-Donachy ventricular assist device in postcardiotomy patients with cardiogenic shock

Radionuclide Assessment of the Natural Heart Ejection Fraction before and after LVAD Implantation

Complete pressure unloading of the ventricles can preserve ischemically damaged myocardium. Most clinical left heart assist device (LVAD) systems used after ischemic injury of the heart apply atrial cannulation which does not ensure pressure unloading. In order to assess the effect of the implantation of an intracorporeal LVAD on the function of the natural heart, we determined the ejection fraction (EF) in four male Holstein calves (90–105 kg) before and after insertion of a Cleveland Clinic pneumatic LVAD. A gated blood pool scan was obtained with a gamma camera after injection of 40 mCi Tc-labelled albumin. The animals were restrained in a sling to avoid movement artifacts.

All animals showed a drop of 65 ± 12% to 42 ± 14% EF in the first postoperative (p.o.) week. Left ventricular output did not maintain sufficient blood pressure as assessed by pump-off tests. Systolic blood pressure dropped from 122 ±6.5 mm Hg to 81 ± 6 mm Hg without pump support on the morning of the first p.o. day.

Apical coring and possible restrained heart movement by the implanted LVAD may lead to impaired myocardial function that renders the individual LVAD dependent until adaptative corrections take place.

Reduction of Haemorrhagic Complications during Mechanically Assisted Circulation with the Use of a Multi-System Anticoagulation Protocol

Two different anticoagulation protocols were used in 49 consecutive patients mechanically supported either for bridge to transplantation (11) or for recovery of myocardial function after cardiac surgery (35). In 46 patients a Biomedicus centrifugal pump was used and in 3 patients a Pierce-Donachy ventricles. Mechanical support was provided to the left ventricle in 14 patients, to the right ventricle in 6 and to both ventricles in 12 patients; an extra-corporeal membrane oxygenator (ECMO) support was used in 17 patients. Thirty-seven males and 12 females, aged 0.2 to 58 years, were supported for an average time of 6.3 days (range 1-43). Anticoagulation was either based on a continuous infusion of heparin in the first 27 patients (group A) or on a multi-system therapy (“La Pitié” protocol) in the other 22 patients (group B). Overall survival rate was 47%. Patients in group A had a 30% (8/27) survival rate, whereas in group B a 68% (15/22) survival rate was observed (p=0.006). Transplantation and ventricular assist device (VAD) removal was successfully obtained in 59% (16/27) and 91% (20/22) of patients in group A and group B respectively (p=0.05). Significant bleeding occurred in 21 patients (81%) in group A and in 2 (9%) of group B (p=0.001). In these patients bleeding averaged 230 ± 231 ml/kg in group A versus 55 ± 18 ml/kg in group B (p=0.001). Surgical revision was necessary for cardiac tamponade or persistent bleeding in 12 patients of group A (25 procedures: mean 0.9/ patient) and in 3 patients of group B (one each patient: mean 0.1/patient) (p=0.01). Infection, thrombo-embolism and brain hemorrhage were also less frequent in group A than in group B. Our data suggest that the “La Pitié” protocol provides a better control of bleeding than the conventional heparin infusion in patients receiving assist device, this reduction in thrombo-hemorrhagic complications might improve the results of mechanical circulatory support.

Review article : Mechanical ventricular support in the management of postcardiotomy cardiogenic shock

'For many reasons clinicians hesitate to employ mechanical devices of unproved efficacy except in the most critically ill patients and then only as a desperate measure. These approaches accounted for a substantial lag time between intra-aortic balloon pump availability and widespread utilization. Ventricular assist devices, recently approved for initial clinical trials, face the same dilemmas'. Norman, 1977.1

Risk analysis in patients bridged to transplantation

BACKGROUND

Efforts to predict mortality in bridge to cardiac transplant patients have concentrated on preventricular assist device (VAD) status. To more fully identify factors influencing survival to transplant, we reviewed the preoperative and postoperative VAD courses of 105 bridge to transplant patients.

METHODS

Sixty-four parameters (34 pre-VAD, 30 post-VAD), including hemodynamics, complications, and evaluations of major organ function were examined and analyzed.

RESULTS

Thirty-three patients (31%) died on VADs and 72 were transplanted. There were two posttransplant operative deaths (3%). By univariate analysis 23 of 64 factors were significant. These 23 factors were entered into a stepwise logistic regression analysis to identify predictors of survival to transplant. Four factors, including pre-VAD intubation (p < 0.005), cardiopulmonary bypass (CPB) time during VAD insertion (p < 0.0001), mean pulmonary artery pressure (first postoperative day after VAD) (p < 0.0002), and highest post-VAD creatinine (p < 0.01) were independent predictors of transplantation.

CONCLUSIONS

Other than the need for intubation, pre-VAD variables were of little value in predicting survival to transplant. Problems during VAD insertion (long CPB time) and post-VAD renal insufficiency were independent predictors. Severe complications that developed during the interval of VAD support, including cerebrovascular accident, bleeding and infection, were surprisingly not predictors for transplantation.

Tirofiban Administration Attenuates Platelet and Platelet-Neutrophil Conjugation but not Neutrophil Degranulation during In Vitro VAD Circulation

Ventricular Assist Devices (VADs) have been used as bridges to heart transplantation. However, VAD circulation is complicated by the incidence of thromboembolism, prolonged bleeding, and activation of the inflammatory cascade. We hypothesize that platelet and neutrophil activation are interrelated and linked to the activation of the glycoprotein (GP) IIb/IIIa platelet receptor. The purpose of this study is to evaluate the effects of Tirofiban, a platelet GP IIb/IIIa receptor inhibitor, on platelet and neutrophil activation during simulated VAD circulation. Two groups of five in vitro VAD circuits were simulated with and without Tirofiban using 450 cc of human blood. Blood samples were drawn at specific time intervals up to 72 hours, measuring leukotriene C4 (LTC4), platelet factor four (PF4), and neutrophil elastase. Tirofiban decreased serum levels of PF4 and LTC4 during VAD circulation. Neutrophil elastase secretion was not affected by Tirofiban administration. Preconditioning of VAD circulation with Tirofiban attenuated platelet activation as demonstrated by a decrease in serum PF4 levels. Tirofiban administration ameliorates the inflammatory response by altering platelet-neutrophil interaction as demonstrated by a decrease in LTC4 production. Continued elastase secretion indicates that the inflammatory response is not completely inhibited by Tirofiban administration. These results suggest that neutrophils may be activated by alternative mechanisms. Early complement activation has been demonstrated during in vivo and in vitro VAD circulation and may play a role in mediating inflammatory and thromboembolic reactions during VAD use.

Glycoprotein IIb/IIIa receptor inhibitor attenuates platelet aggregation induced by thromboxane A2 during in vitro nonpulsatile ventricular assist circulation

A recent development in antithrombotic research allows the inhibition of platelet aggregation via protection of the glycoprotein IIb/IIIa receptor on the platelet membrane. We hypothesized that a GP IIb/IIIa receptor inhibitor would inhibit thromboxane-induced platelet aggregation during circulation in our in vitro ventricular assist device (VAD) circuit and preserve long-term platelet function. Twenty-one in vitro nonpulsatile centrifugal VAD circuits were simulated for 4 days using 450 ml of fresh human whole blood with or without glycoprotein IIb/IIIa receptor inhibitor (tirofiban). Platelet aggregation and degranulation were measured in whole blood induced by ristocetin, collagen, ADP, and thromboxane A2 (TXA2). The tirofiban-treated group preserved the platelet count and tended to exert these beneficial effects by inhibiting pathologic platelet aggregation induced by TXA2, collagen, and ADP as well as degranulation. Tirofiban may be useful in preserving platelet number and function during clinical VAD use.

Improved results for postcardiotomy cardiogenic shock with the use of implantable left ventricular assist devices

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 +/- 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.

Evaluation of a pulsatile pediatric ventricular assist device in an acute right heart failure model

BACKGROUND

The development of pulsatile ventricular assist devices for children has been limited mainly by size constraints. The purpose of this study was to evaluate the MEDOS trileaflet-valved, pulsatile, pediatric right ventricular assist device (stroke volume = 9 mL) in a neonatal lamb model of acute right ventricular failure.

METHODS

Right ventricular failure was induced in ten 3-week-old lambs (8.6 kg) by right ventriculotomy and disruption of the tricuspid valve. Control group 1 (n = 5) had no mechanical support whereas experimental group 2 (n = 5) had right ventricular assist device support for 6 hours. The following hemodynamic parameters were measured in all animals: heart rate and right atrial, pulmonary arterial, left atrial, and systemic arterial pressures. Cardiac output was measured by an electromagnetic flow probe placed on the pulmonary artery.

RESULTS

All results are expressed as mean +/- standard deviation and analyzed by Student's t test. A p value less than 0.05 was considered statistically significant. Base-line measurements were not significantly different between groups and included systemic arterial pressure, 80.6 +/- 12.7 mm Hg; right atrial pressure, 4.6 +/- 1.6 mm Hg; mean pulmonary arterial pressure, 15.6 +/- 4.2 mm Hg; left atrial pressure, 4.8 +/- 0.8 mm Hg; and cardiac output, 1.4 +/- 0.2 L/min. Right ventricular injury produced hemodynamics compatible with right ventricular failure in both groups: mean systemic arterial pressure, 38.8 +/- 10.4 mm Hg; right atrial pressure, 16.8 +/- 2.3 mm Hg; left atrial pressure, 1.4 +/- 0.5 mm Hg; and cardiac output, 0.6 +/- 0.1 L/min. All group 1 animals died at a mean of 71.4 +/- 9.4 minutes after the operation. All group 2 animals survived the duration of study. Hemodynamic parameters were recorded at 2, 4, and 6 hours on and off pump, and were significantly improved at all time points: mean systemic arterial pressure, 68.0 +/- 13.0 mm Hg; right atrial pressure, 8.2 +/- 2.3 mm Hg; left atrial pressure, 6.4 +/- 2.1 mm Hg; and cardiac output, 1.0 +/- 0.2 L/min.

CONCLUSIONS

The results demonstrate the successful creation of a right ventricular failure model and its salvage by a miniaturized, pulsatile right ventricular assist device. The small size of this device makes its use possible even in small neonates.

Management of left ventricular assist device infection with heart transplantation

BACKGROUND

Left ventricular assist devices (LVADs) are being used as bridges to heart transplantation (HT). Infection of the LVAD in this patient population represents a serious complication, as simple LVAD removal or delaying HT may result in death. To improve outcomes in this group of patients, we performed HT in the presence of LVAD infection.

METHODS

Eighteen patients underwent LVAD implantation followed by HT. Ten underwent HT in the absence of LVAD infection (group 1); and 8, in the presence of LVAD infection (group 2). All patients were treated similarly except for modification of immunosuppression in group 2 patients.

RESULTS

Infectious and noninfectious complications were equivalent between the two groups. There was no difference between groups in regard to intraoperative deaths (one versus none), long-term survival (8/10 versus 7/8), wound complications (three versus none), and mean length of hospital stay after HT (21 versus 26 days).

CONCLUSIONS

Patients with LVAD infection are too seriously ill to allow LVAD removal or delay of HT. Transplantation in the face of infection is an effective treatment option.

A valveless high stroke volume counterpulsation device restores hemodynamics in patients with congestive heart failure and intractable cardiogenic shock awaiting heart transplantation

The paraaortic counterpulsation device is a round pumping chamber with one valveless opening 20 mm in diameter and a 100 ml stroke volume. The paraaortic counterpulsation device was implanted on the ascending aorta of three male patients with intractable cardiogenic shock. Patients were assisted for 4 hours and 8 and 54 days, respectively; the first patient died as a result of nonresponding peripheral vasodilation and the other two died of septic shock. The two patients who were assisted for 8 and 54 days were conscious and able to function in a limited manner during the mechanical assistance. Discontinuation of the mechanical support for a few seconds was followed by low systolic arterial pressure (30 to 60 mm Hg) and syncopal episodes. Biochemical tests and autopsy results in these patients showed no evidence of blood cell destruction, thrombus formation, brain infarction, or other distal emboli. In conclusion, satisfactory hemodynamic effects, excellent biocompatibility, and simplicity of the implantation procedure in these patients encourage the use of the paraaortic counterpulsation device as a bridge to heart transplantation.

Improved mortality and rehabilitation of transplant candidates treated with a long-term implantable left ventricular assist system

OBJECTIVE

This nonrandomized study using concurrent controls was performed to determine whether the HeartMate implantable pneumatic (IP) left ventricular assist system (LVAS) could provide sufficient hemodynamic support to allow rehabilitation of severely debilitated transplant candidates and to evaluate whether such support reduced mortality before and after transplantation.

METHODS

Outcomes of 75 LVAS patients were compared with outcomes of 33 control patients (not treated with an LVAS) at 17 centers in the United States. All patients were transplant candidates who met the following hemodynamic criteria: pulmonary capillary wedge pressure > or = 20 mm Hg with a systolic blood pressure < or = 80 mm Hg or a cardiac index < or = 2.0 L/minute/m2. In addition, none of the patients met predetermined exclusion criteria.

RESULTS

More LVAS patients than control patients survived to transplantation: 53 (71%) versus 12 (36%) (p = 0.001); and more LVAS patients were alive at 1 year: 48 (91%) versus 8 (67%) (p = 0.0001). The time to transplantation was longer in the group supported with the LVAS (average, 76 days; range, < 1-344 days) than in the control group (average, 12 days; range, 1-72 days). In the LVAS group, the average pump index (2.77 L/minute/m2) throughout support was 50% greater than the corresponding cardiac index (1.86 L/minute/m2) at implantation (p = 0.0001). In addition, 58% of LVAS patients with renal dysfunction survived, compared with 16% of the control patients (p < 0.001).

CONCLUSIONS

The LVAS provided adequate hemodynamic support and was effective in rehabilitating patients based on improved renal, hepatic, and physical capacity assessments over time. In the LVAS group, pretransplant mortality decreased by 55%, and the probability of surviving 1 year after transplant was significantly greater than in the control group (90% vs. 67%, p = 0.03). Thus, the HeartMate IP LVAS proved safe and effective as a bridge to transplant and decreased the risk of death for patients waiting for transplantation.

Linear end-systolic pressure-volume relationship during pulsatile left ventricular bypass represents native heart function

This study assessed whether the end-systolic pressure-volume relationship obtained without any interventions during pulsatile left ventricular bypass adequately represents native heart function. In 11 anesthetized Holstein calves, left ventricular pressure was measured with a micromanometer while left ventricular volume was simultaneously calculated from orthogonal left ventricular diameters measured with ultrasonic dimension transducers. End-systolic pressure and volume data were subjected to linear regression analysis to achieve an end-systolic pressure-volume relationship. Data from both caval occlusions and aortic occlusion were used for the control end-systolic pressure-volume relationship (median r = 0.941, slope = 7.4 +/- 0.8 mm Hg per milliliter per 100 gm left ventricular weight; mean +/- standard error of the mean). During left atrial-aortic bypass with a Pierce-Donachy pneumatic assist pump in the asynchronous mode, the end-systolic pressure-volume relationships were obtained without interventions to change ventricular loading conditions. During maximal ventricular unloading during full to empty pumping, termed 100%, the resulting narrow range of pressure and volume data did not yield highly linear end-systolic pressure-volume relationships (median r = 0.669, slope = 4.9 +/- 0.9 mm Hg per milliliter per 100 gm left ventricular weight). However, at reduced rates off pumping, the end-systolic pressure-volume relationships were considerably linear (80%, median r = 0.819; 60%, median r = 0.868; 40%, median r = 0.899). Slopes did not significantly differ from control values (80%, 6.9 +/- 1.1; 60%, 8.2 +/- 1.1; 40%, 7.8 +/- 1.1). The end-systolic pressure-volume relationship obtained without exogenous load changes during asynchronous, pulsatile left ventricular bypass represents native left ventricular systolic function.

Circulatory support with shock due to acute myocardial infarction

Cardiogenic shock after acute myocardial infarction develops according to the amount of lost myocardium, function of remote myocardium, and the phenomenon of infarct expansion. Patients treated with mechanical support alone, without additional measures, have a mortality rate of 80%, the same as patients treated medically. Emergency angioplasty and emergency coronary artery bypass grafting can reduce mortality in certain subsets of patients to 40%. Patients with more severe shock and secondary organ dysfunction may be treated with mechanical bridging to transplantation with survival rates varying between 45% and 76%. Percutaneous support systems may be used to resuscitate a patient or to temporize, allowing time to perform diagnostic studies to determine if the patient is suitable for revascularization or heart transplantation. Intravenous enoximone may improve cardiac function as well and thus allow better decision making for further therapy.

Effect of synchronous and asynchronous pulsatile flow during left, right, and biventricular bypass

Ventricular assist devices augment flow from the left atrium to the aorta and/or from the right atrium to the pulmonary artery. Most devices are used in the asynchronous full-to-empty mode (asynchronous) but may also be used in a synchronous counterpulsation mode (synchronous). This study determines the optimal assist modes to reduce myocardial oxygen consumption (MVO2) and metabolism. Twelve pigs were instrumented with carotid artery and Baim coronary sinus catheters for determination of MVO2 and myocardial lactate production (LACT). Six were implanted with a Pierce-Donachy left ventricular assist device (LVAD) and 6 with both right and left ventricular assist devices (BIVAD). Two periods each of control, synchronous, and asynchronous bypass were instituted, the midanterior descending coronary artery (LAD) was ligated, and the sequence was repeated. After each period, MVO2 and LACT were determined and myocardial biopsy specimens were obtained for tissue, lactate, and ATP assay. Following LAD ligation, biopsy specimens were obtained from both the infarct and noninfarct zones of the heart. MVO2 decreased (p < 0.05) in the asynchronous BIVAD mode compared with control. MVO2 was unchanged in synchronous BIVAD or either LVAD mode. Tissue ATP and tissue lactate were unaffected by any mode of bypass. Only BIVAD in the asynchronous mode reduced MVO2. When ventricular assist devices are utilized to aid recovery of the natural heart, two devices should always be inserted to allow biventricular assist. Synchronous counterpulsation offers no advantage.

Multicenter clinical evaluation of the HeartMate 1000 IP left ventricular assist device

The Thermo Cardiosystems Inc (Woburn, MA) HeartMate 1000 IP left ventricular assist device (LVAD) has been evaluated as a bridge to transplantation in 34 patients for up to 324 days at seven clinical centers in the United States. Sixty-five percent of the patients underwent transplantation, 80% of whom were discharged from the hospital. Six additional control patients, transplant candidates who met the entrance criteria but who did not receive the device, were also included in the study. Although 3 (50%) of the control patients received transplants, all 6 died within 77 days of having met the LVAD inclusion criteria (100% mortality). Complications resulting from use of the device were comparable with those previously reported for all ventricular assist devices, except for thromboembolic events: bleeding, 39%; infection, 25%; and right heart failure, 21%. No device-related thromboembolic events occurred, although 1 patient experienced an event related to a mechanical aortic valve in the native heart. None of the complications had a significant negative association with outcome of the patient except for right heart failure. All survivors had a significant improvement in hepatic function before transplantation. Total bilirubin values were reduced by 60% during LVAD support. No significant differences were observed when total bilirubin values were compared at 30 and 60 days after LVAD support and at 30 and 60 days after transplantation in a cohort of 15 patients (p greater than 0.05). The improvement in renal function was less predictable than that of hepatic function. Creatinine values decreased significantly before transplantation; however, the values measured at 30 and 60 days after transplantation were higher than those measured at the same intervals after LVAD support had been initiated, and this increase is presumably related to the immunosuppressive drugs. In conclusion, the HeartMate 1000 IP LVAD has been shown to be effective in supporting end-stage cardiomyopathy patients to transplantation. Thromboembolism, previously regarded as a serious complication with such devices, has not been a problem with this device. Additional patients are being enrolled into the study to further document the safety and effectiveness of this technology.

Treatment of cardiogenic shock with the Hemopump left ventricular assist device

A multiinstitutional study is in progress to evaluate the Hemopump in the treatment of cardiogenic shock. Fifty-three patients with refractory cardiogenic shock were selected for Hemopump assistance. The hemodynamic definition of cardiogenic shock included (1) a cardiac index of less than 2.0 L.min-1.m-2, (2) pulmonary capillary wedge pressure of greater than 18 mm Hg, and (3) a systolic blood pressure of less than 90 mm Hg or a left ventricular work index of less than 1,500 g-m.m-2.min-1. The Hemopump was successfully inserted in 41 of 53 patients (77.3%). A significant improvement in the hemodynamic status was seen during Hemopump assistance. A minimal level of hemolysis was observed. No leg ischemia was observed. The 30-day overall survival of the Hemopump group was 31.7%. Criteria establishing indications for use and clinical utility are proposed. We conclude that the Hemopump provides significant hemodynamic support of the patient in cardiogenic shock allowing for recovery from ventricular stunning in marginal ventricles, and that in select patients the Hemopump may offer a major improvement in survival over conventional therapy.

Bio-medicus ventricular assist device for salvage of cardiac surgical patients

Over a 5-year period, 41 (1%) of 4,193 patients undergoing cardiac operations underwent intraoperative or early postoperative insertion of a Bio-Medicus ventricular assist device when it became apparent that the patient could not otherwise survive. Fourteen patients were in cardiogenic shock and 7 were in cardiac arrest at the time of initiation of their primary cardiac surgical procedure, and in no instance was the device planned as a bridge to cardiac transplantation. Bleeding, sepsis, and thromboembolism were frequent postoperative complications. Central nervous system deficits were observed in 16 patients during their postoperative course. Eight patients (19.5%) were long-term survivors. Of the preoperative risk factors evaluated only age was significantly associated with survival, with 7 (33%) of the 21 younger (39 to 63 years) patients surviving. Blood product usage and hospital cost were analyzed in an attempt to assess cost/effectiveness of use of this device for attempted salvage of such desperately ill patients.

In-vitro assessment of centrifugal pumps for ventricular assist

Currently two major types of centrifugal pumps are commercially available for ventricular assist: the Biomedicus-cone (Group I) and the Centrimed-impeller pump (now Sarns 3M) (Group II). To compare them for blood trauma and hemolysis, an in-vitro experiment was designed with a Stöckert roller pump as a standard control (Group III). The in-vitro circuit was constructed consisting of a pump head, electromagnetic flow probe, polyvinyl chloride tubing and a reservoir, identical for all groups. Human ACD blood was used for priming and was circulated with a flow rate of 2 L/min for 24 h. Blood samples were taken at 0, 1, 3, 6, 12, and 24 h and zero control values were subtracted from the resulting data per time interval. Among the 16 parameters studied, a highly significant difference in favor of Group I was found for glutamate oxalacetate transaminase (GOT) and lactate dehydrogenase (p less than 0.0001) and for the free plasma hemoglobin (p less than 0.0001) after 12 and 24 h, respectively. The hemolytic index (Allen) again was lowest for group I in contrast to Groups II and III (0.012 versus 0.060 and 1.70) after 24 h. All other parameters studied did not render significant differences between the systems tested. The authors conclude that the Biomedicus pump currently is the least traumatic centrifugal pump for ventricular assist.

Hemodynamic predictors for weaning patients from ventricular assist devices (VADs)

In order to find hemodynamic parameters that can accurately predict whether patients can be successfully weaned from ventricular assist devices (VADs), we studied data from 17 patients supported with Pierce-Donachy VADs [11 left VAD (LVAD); 6 right VAD (RVAD)] following cardiogenic shock for periods from 1.3 to 22 days (mean 5.4). Myocardial recovery was determined by daily measurements of "pump on pump off" parameters, and the data from the 8 LVAD patients and 3 RVAD patients whose hearts recovered were compared to the data from those whose did not. In this study, daily pump on pump off hemodynamic measurements were found to be predictive of success for weaning patients from VADs. In particular, the most significant predictors were: increases in mixed venous oxygen saturation, cardiac index, mean arterial pressure and ventricular ejection fraction, as well as decreases in atrial pressures. An index for measuring hemodynamic function with the VAD off is proposed, as are models of recovery. Seventy percent of the patients weaned from VADs survived, indicating that patients appropriately weaned from VAD support have a reasonable chance for survival.

Extracorporeal membrane oxygenation for circulatory support after repair of congenital heart defects

Extracorporeal membrane oxygenation was used for cardiovascular support in 13 infants and children with complex congenital heart disease and 1 premature neonate treated in preparation for pericardial patch tracheoplasty for long-segment tracheal stenosis. Nine patients were weaned from extracorporeal membrane oxygenation. There were five (36%) early deaths and four (29%) late deaths. Cannulation sites included right carotid/jugular vessels, femoral artery and vein, and right atrium and aorta. In 4 patients, the neck vessels were repaired at decannulation. Five survivors had normal growth and neurodevelopmental evaluations at follow-up. Extracorporeal membrane oxygenation can be successfully used as biventricular support in patients with intractable low cardiac output syndrome after repair of congenital heart disease. Best results are obtained in patients who have several hours of stability after operation before initiation of support. Hemorrhagic complications are reduced and long-term neurodevelopmental outcomes appear promising with right neck vessel cannulation and repair. No bleeding complications were observed in patients cannulated through the neck vessels.

The Pierce-Donachy ventricular assist device as a bridge to cardiac transplantation

The Pierce-Donachy ventricular assist device (VAD) was used as an attempted bridge to orthotopic cardiac transplantation in 12 patients aged 13 to 55 years. Ischemic (4 patients), dilated (4 patients), acute viral (1 patient), postpartum (1 patient), and hypertrophic cardiomyopathy (1 patient), along with a failed transplant (1 patient), were the causative factors of end-stage cardiomyopathy in these patients. All patients were candidates for orthotopic cardiac transplantation but sustained refractory cardiogenic shock (cardiac index less than 2 L/min/m2). Left VADs were placed in all patients; 7 also required right VADs. Four patients died of hemorrhagic complications less than 24 hours after VAD insertion. Ventricular assist device stabilization was successful in 8 patients and support ranged from eight hours to 64 days. Seven patients successfully underwent orthotopic cardiac transplantation. One died postoperatively of hemorrhagic complications, 6 were discharged from the hospital, and 1 patient died at 3 months of cytomegalovirus infection. Five patients are long-term survivors. The Pierce-Donachy VAD is an effective means for supporting critically ill patients with end-stage cardiomyopathy and cardiogenic shock before orthotopic cardiac transplantation. Death is related to hemorrhagic, rather than infectious or thromboembolic, complications. Patients successfully stabilized with the VAD can undergo orthotopic cardiac transplantation with acceptable mortality and morbidity rates.

Use of the Pierce-Donachy ventricular assist device in patients with cardiogenic shock after cardiac operations

In spite of recent improvements in cardiac surgery, a small percentage of patients have severe postcardiotomy ventricular failure refractory to drugs and the intraaortic balloon. In our experience, the Pierce-Donachy external pneumatic ventricular assist device has proved to be one of the most effective devices for these patients. Since 1981, 30 patients aged 15 to 71 years (mean age, 52 years) with profound cardiogenic shock refractory to conventional therapy after cardiotomy were supported with the Pierce-Donachy ventricular assist device. Fourteen required left ventricular support, 7 needed right ventricular support with an intraaortic balloon, and 9 had biventricular assistance. Duration of support ranged from three hours to 22 days (mean length, 3.6 days). Seven of the first 11 patients seen died in the operating room of bleeding, biventricular failure, or both. However, 16 patients (53%) had improved cardiac function, 15 (50%) were weaned, and 11 (37%) were discharged. Of the last 19 patients in the series, 47% survived. Factors affecting survival were myocardial infarction (75%) and renal failure (90%). Common complications were bleeding (73%) and biventricular failure (83%).

Surgical techniques for the implantation of heterotopic prosthetic ventricles

Mechanical support of the failing heart is becoming an increasingly useful tool for bridging to cardiac transplantation and for recovery of the natural heart. Several options exist for cannulation sites during the implantation of the heterotopic prosthetic ventricles. These options include the left atrial appendage, the left ventricular apex, the interatrial groove, and the left atrial roof. The indications, contraindications, advantages, disadvantages, and surgical technique for each option are described. Operation of the drive console and postoperative care are also discussed.

Implantable electrical left ventricular assist system: bridge to transplantation and the future

An implantable left ventricular assist system (LVAS) utilizing an electromechanically driven dual pusher-plate blood pump has been employed in a multiinstitutional trial as a bridge to cardiac transplantation. Under development for permanent circulatory support in patients with end-stage heart disease, the LVAS, in this application, derives power and control from an external console via a percutaneous lead. The LVAS was implanted in 20 patients (16 men, 4 women) who were hemodynamically unstable or in refractory cardiogenic shock. The mean age was 44.9 years (range, 25 to 63 years). Preoperative diagnosis was evenly divided between end-stage ischemic disease, cardiomyopathy, and acute myocardial infarction. Implanted in the left upper quadrant within the anterior abdominal wall, the blood pump was connected between the left ventricular apex and ascending aorta. Total support of the systemic circulation and substantial left ventricular unloading were achieved with synchronous counterpulsation for periods up to 90 days (mean, 22.7 days). All patients were stabilized hemodynamically. The mean preoperative cardiac index of 1.5 L/min/m2 increased by a factor of 2. Pulmonary arterial pressures decreased substantially. Serious complications occurred in 16 patients, precluding cardiac transplantation in 10. Most complications (greater than 70%) were in patients who did not receive transplants; the most common complication was bleeding. Twelve of 13 patients with LVAS implants for more than seven days were mobilized, and 4 were fully ambulatory and completely rehabilitated. Orthotopic cardiac transplantation was performed in 10 patients after implants ranging from two to 90 days (mean, 30.3 days).(ABSTRACT TRUNCATED AT 250 WORDS)

Bridging to cardiac transplantation with pulsatile ventricular assist devices

As cardiac transplantation becomes more commonplace in the treatment of end-stage heart failure and as suitable donors become less available, an increasing number of patients will require mechanical circulatory assistance to bridge to transplantation. Since 1982, refractory hemodynamic instability requiring placement of pulsatile ventricular assist devices (VADs) has developed in 11 candidates for transplantation aged 24 to 54 years (mean, 39.6 years). A pneumatic Pierce-Donachy pump was used in 9 patients and an electrical Novacor pump in 2. The cause of the cardiomyopathy was ischemic in 6, postpartum in 2, idiopathic in 2, and doxorubicin hydrochloride toxicity in 1. Seven patients required left ventricular support (LVAD); 4 required biventricular mechanical support (BVAD). Duration of support ranged from 8 hours to 91 days with flows ranging from 4.1 to 8.5 L/min (mean, 5.5 L/min). Although hemodynamic stability was achieved in all 11 patients, contraindications to transplantation developed in 5 patients during VAD support (renal failure in 4, sepsis in 3, disseminated intravascular coagulopathy in 1). The remaining 6 patients (4 with an LVAD, 2 with a BVAD) remained good candidates for transplantation despite major complications in 5 (mediastinal bleeding in 3, driveline infection in 3, development of preformed antibodies in 2, small embolic stroke caused by device malfunction in 1). The 3 patients who were supported the longest (24, 75, and 91 days) were ambulatory while awaiting a donor heart. All 6 patients underwent successful transplantation after 8 hours to 91 days (mean, 24 days) of support. Other than one sternal wound infection, there were no major complications after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterotopic prosthetic ventricles as a bridge to cardiac transplantation. A multicenter study in 29 patients

Heterotopic prosthetic ventricles were used to support the circulation in 29 candidates for heart transplantation who were expected to die before procurement of a donor heart. Twenty-one of these patients (average age, 36 years) underwent successful transplantation after 8 hours to 31 days of circulatory support. The other eight patients died because their condition could not be stabilized for transplantation, despite restoration of blood flow. Fourteen patients received biventricular support; 15 received only left ventricular support, with pharmacologic assistance of right heart function. Before transplantation, blood flow from the left prosthetic ventricle averaged 2.8 +/- 0.4 liters per minute per square meter of body-surface area, and from the right prosthesis 2.4 +/- 0.4 liters, as compared with an average flow of 1.6 +/- 0.5 liters per minute per square meter before implantation. Of the 21 patients who received heart transplants, 20 were discharged from the hospital after a median of 31 days. Nineteen patients were alive at 7 to 39 months, and 11 of the first 12 were alive at one year. We conclude that heterotopic placement of prosthetic ventricles as a bridge to transplantation provides an effective method of temporarily supporting cardiac function in critically ill patients without removing the natural heart. The early survival rate after transplantation is similar to that with elective cardiac transplantation.

[Successful post-bypass extracorporeal circulatory assistance with the centrifugal pump]

Patients with reduced left ventricular function do have an increased risk of inability to be weaned off bypass after open heart surgery despite maximal pharmacologic support and intraaortic balloon counter-pulsation. Centrifugal pumps used for extracorporeal circulatory assist can maintain a patient in low cardiac output up to days without anticoagulation. We used a centrifugal pump in 3 patients: as a left ventricular assist device (LVAD) in 2 patients and right ventricular assist device (RVAD) in 1 patient. One LVAD-patient became a long-term survivor after 20 h of assist, another was bridged successfully to an open heart procedure for 2 h after papillary muscle rupture. One RVAD patient died on the operating table due to massive tracheal bleeding probably caused by pulmonary hypertension.

A new ventricu lar assist device for acute cardiac failure: report of initial use for biventricular support

A new ventricular assist device (VAD) developed by Symbion, Inc., received its initial biventricular clinical use in a 53-year-old man suffering cardiogenic shock from severe congestive heart failure secondary to cardiomyopathy and a 15-year history of coronary artery disease.

The eight-day period of biventricular support on the Symbion devices was satisfactory in spite of two complications probably unrelated to the pump. First, a neurologic deficit was noted after transition from the temporary support pumps to the Symbion pumps, ostensibly from a small air bolus entering the aortic return line. The deficit was deemed mild and reversible, and the patient showed improvement. Secondly, poor renal function secondary to prolonged hypotension associated with cardiac arrest persisted throughout the support period. All other organs, however, were well supported.

On the eighth day of support, a dramatic change in hepatic function and neurologic deterioration justified termination of support. At explant of the devices, a kink and an occluding thrombus were found at the inferior port of the right atrial outflow cannula, undoubtedly the cause of the declining hepatic status. Clots were also found adherent to both VAD chambers at the air vents, but no evidence of emboli was found at autopsy.

Redesign of the air vent sites and cannulae may be required to improve the Symbion VAD's performance.

Clinical application of left ventricular assist devices

In Japan, 32 patients have had application of monoventricular and biventricular assist devices during the past three years. Five of the 32 patients treated by the Fall of 1986 have successfully achieved long-term survival. In this paper we describe our experience with the Tomasu and Pierce VAD in a total of four and two patients, respectively. Four of the six patients could be successfully weaned from the VAD and two of them were long-term survivors. Nonsynchronizing pumping of the VADs was effective, as well as synchronizing pumping. Anticoagulant therapy is highly recommended during the use of the VAD although there was no significant incidence of thromboembolism or thrombus in the devices in this clinical series.

Implantation of the left ventricular assist device

Development of mechanical devices for support of the failing heart is a major goal in cardiac surgery. The application of left ventricular assist device (LVAD) is a promising approach in the case of severe and otherwise untreatable cardiac failure. In our experience we have used two external centrifugal pumps for the extracorporeal biventricular cardiac support in a post-transplantation patient who experienced severe rejection six months after heart transplantation. Our own series includes a total of ten implantations of LVAD's with six patients who could be weaned from the device but only one long-term survivor. The clinical results are not encouraging which suggests that the heart of the patient who needs an LVAD has been damaged beyond any chance for later recovery. Obviously timing is the most crucial aspect of the decision to implant the device. It would appear that orthotopic implantation of the transplanted heart remains the method of definitive treatment.