Improved multiorgan function after prolonged univentricular support

Neurohormonal Regulation and Improvement in Blood Glucose Control: Reduction of Insulin Requirement in Patients with a Nonpulsatile Ventricular Assist Device

<p><b>Background:</b> Heart failure is associated with prolonged stress and inflammation characterized by elevated levels of cortisol and circulating catecholamines. Persistent sympathetic stimulation secondary to the stress of heart failure causes an induced insulin resistance, which creates a need for higher doses of insulin to adequately manage hyperglycemia in this patient population. We hypothesized that cortisol and catecholamine levels would be elevated in end-stage heart failure patients, however, would be reduced after the implantation of a left ventricular assist device (LVAD). Insulin requirements would therefore be reduced post LVAD implant and control of diabetes improved as compared with pre-implant.</p><p><b>Methods:</b> Pre- and postoperative cortisol, catecholamine, glycated hemoglobin, and blood glucose levels were evaluated retrospectively in 99 LVAD patients at a single center from January 2007 through November 2011. Serum was collected before LVAD implantation and monthly after implantation for 12 months consecutively. Results were evaluated and compared to insulin requirements, if any, before and after implant. Plasma levels were measured by ELISA.</p><p><b>Results:</b> There were a total of 99 patients (81 men and 18 women). Two patients were implanted twice due to pump dysfunction. Mean age was 59 years, � 10, with a median of 63 years. Of those patients, 64 had ischemic cardiomyopathy and 35 had dilated cardiomyopathy. The total patient years of LVAD support were 92.5 years. All patients received a continuous flow left ventricular assist device. Type II diabetes mellitus was diagnosed in 28 patients. Of those patients, 24 required daily insulin with an average dose of 45 units/day. Average preoperative glycated hemoglobin (HbA1c) levels were 6.8% with fasting blood glucose measurements of 136 mg/dL. Mean cortisol levels were measured at 24.3 ?g/dL before LVAD implantation, with mean plasma catecholamine levels of 1824 ?g/mL. Post operatively, average HbA1c levels were 5.38% with fasting blood glucose measurements of 122 mg/dL. Mean cortisol levels were measured at 10.9 ?g/dL with average plasma catecholamine levels were 815 ?g/mL. There was a significant decrease in both cortisol levels post LVAD implant (<i>P</i> = 0.012) as well as catecholamine levels (<i>P</i> = 0.044). The average insulin requirements post LVAD implant were significantly reduced to 13 units/day (<i>P</i> = 0.001). Six patients no longer required any insulin after implant.</p><p><b>Conclusion:</b> Implantation of nonpulsatile LVADs has become a viable option for the treatment of end-stage heart failure, helping to improve patient quality of life by decreasing clinical symptoms associated with poor end-organ perfusion. Frequently, diabetes is a comorbid condition that exists among heart failure patients and with the reduction of the systemic inflammatory and stress response produced by the support of a nonpulsatile LVAD, many patients may benefit from a reduction in their blood glucose levels, as well as insulin requirements.</p>

Long-term continuous flow left ventricular assist device support and end-organ function: prospects for destination therapy

Pulsatile flow left ventricular assist devices (PF-LVADs) have successfully supported patients with severe heart failure for bridge-to-transplant (BTT) and destination therapy (DT). End-organ dysfunction is often reversed, optimizing the patient's condition to enhance survival, and quality of life. Questions have been raised regarding the potential for continuous flow LVADs (CF-LVADs) to provide the same quality of circulatory support. Prior research showing that PF is superior to continuous, non-PF does not appear to be relevant with CF-LVADs for BTT and DT. Under most clinical conditions, arterial pulsatility is present during CF-LVAD support, and this type of support should not be termed "nonpulsatile." Clinical studies have shown that renal, hepatic, and neurocognitive function is either maintained within a normal range, or is significantly improved, during CF-LVAD support for durations up to 15 months. Results of the randomized clinical trial between the CF HeartMate II and the pulsatile HeartMate XVE (both by Thoratec Corp, Pleasanton, CA, USA) are pending final US Food and Drug Administration (FDA) review and are not yet published. Studies of microcirculation during CF-LVAD support indicate that capillary blood flow is adequate to support cellular function. There are anecdotal cases of patients being supported with a CF-LVAD for over seven years with preserved end-organ function. Presently, there are no clinical reports indicating that end-organ function is not well maintained. Current clinical evidence indicates that end-organ perfusion and function can be well maintained for extended durations of support with a CF-LVAD.

New prioritization of heart transplant candidates on mechanical circulatory support in an era of severe donor shortage

BACKGROUND

Nearly all patients receiving heart transplantation (HTx) in Germany are now those listed in urgent status. In this study we review urgency-based allocation policy for HTx candidates with ventricular assist devices (VADs).

METHODS

We retrospectively studied 345 adult candidates for de novo HTx. Group U (n = 160) comprised patients primarily listed in urgent status without VAD. Group VAD-45 (n = 167) comprised patients with intended bridging to HTx who survived >45 days after VAD implantation (after initial drop in survival rates). Among these patients, those who died of stroke or were awarded urgent status due to difficulties of coagulation management (thrombus formation, thromboembolism and bleeding) in the first year after VAD implantation were assigned to Group COAG (n = 36), and those who died or were awarded urgent status due to device-related infection in the same period were assigned to Group INF (n = 31). Actuarial survival rates were studied in each group.

RESULTS

Survival rates during support in Group VAD-45 were comparable to those during urgent status in Group U. Bridge-to-transplant rate was 63.9% in Group COAG and 58.1% in Group INF. The post-transplant 3-year survival rate of 85.3% in Group COAG was significantly higher than that in Group INF (46.8%, p < 0.01) and Group U (62.4%, p < 0.05).

CONCLUSIONS

Patients who have a VAD for >45 days should be awarded some priority for urgent HTx, which is currently prohibited in Germany. Patients listed in urgent status due to difficulties of coagulation management should be prioritized over those listed for device-related infection to make effective use of limited resources.

Incidence and patterns of adverse event onset during the first 60 days after ventricular assist device implantation

BACKGROUND

Although ventricular assist devices (VADs) provide effective treatment for end-stage heart failure, VAD support remains associated with significant risk for adverse events (AEs). To date there has been no detailed assessment of the incidence of a full range of AEs using standardized event definitions. We sought to characterize the frequency and timing of AE onset during the first 60 days of VAD support, a period during which clinical observation suggests the risk of incident AEs is high.

METHODS

A retrospective analysis was performed utilizing prospectively collected data from a single-site clinical database including 195 patients aged 18 or greater receiving VADs between 1996 and 2006. Adverse events were coded using standardized criteria. Cumulative incidence rates were determined, controlling for competing risks (death, transplantation, recovery-wean).

RESULTS

During the first 60 days after implantation, the most common AEs were bleeding, infection, and arrhythmias (cumulative incidence rates, 36% to 48%), followed by tamponade, respiratory events, reoperations, and neurologic events (24% to 31%). Other events (eg, hemolysis, renal, hepatic events) were less common (rates <15%). Some events (eg, bleeding, arrhythmias) showed steep onset rates early after implantation. Others (eg, infections, neurologic events) had gradual onsets during the 60-day period. Incidence of most events did not vary by implant era (1996 to 2000 vs 2001 to 2006) or by left ventricular versus biventricular support.

CONCLUSIONS

Understanding differential temporal patterns of AE onset will allow preventive strategies to be targeted to the time periods when specific AE risks are greatest. The AE incidence rates provide benchmarks against which future studies of VAD-related risks may be compared.

Left ventricular assist devices: an alternative to medical therapy for end-stage heart failure

Although aggressive medical therapy and ultimately cardiac transplantation have long been the therapeutic mainstays for patients with end-stage heart failure, the left ventricular assist device (LVAD), which was originally used clinically as a bridge to transplantation, may also be used as destination therapy. LVAD therapy for selected patients has been shown in the REMATCH trial to be superior to medical therapy in ameliorating symptoms and improving outcome in patients with terminal heart failure. LVAD therapy has also proved useful in improving native heart function by neuroendocrine modulation and reverse remodeling. Furthermore, current evidence suggests that when LVAD therapy is utilized to improve ventricular function, it may be further enhanced when combined with aggressive medical therapy.

Severe renal dysfunction complicating cardiogenic shock is not a contraindication to mechanical support as a bridge to cardiac transplantation

OBJECTIVES

This study investigated outcomes in patients with cardiogenic shock and severe renal dysfunction treated with ventricular assist devices (VAD) as a bridge to cardiac transplantation.

BACKGROUND

Previous reports have documented poor survival in patients with cardiogenic shock and severe renal dysfunction treated with VAD.

METHODS

We surveyed 215 consecutive patients who received a VAD from 1992 to 2000 and selected patients who had a serum creatinine > or =3.0 mg/dl at the time of VAD placement. Demographic, laboratory, and clinical outcome data were collected.

RESULTS

Eighteen patients met the inclusion criteria. Mean serum creatinine at the time of VAD placement was 4.0 +/- 0.7 mg/dl (range 3.0 to 5.2 mg/dl). Seven patients required temporary renal support with continuous venovenous hemodialysis (CVVHD). Eleven patients underwent cardiac transplantation. At six months post-transplantation, mean serum creatinine was 2.0 +/- 0.6 mg/dl (range 1.3 to 3.5 mg/dl). None of the transplanted patients required subsequent renal support. Seven patients died with a VAD before transplantation. Three died early (<1 month) after VAD placement, and all three required CVVHD until death. Four patients survived for >1 month after VAD placement; all four had resolution of renal dysfunction with mean serum creatinine of 1.9 +/- 1.2 mg/dl (range 0.8 to 3.6 mg/dl) without the need for renal support. Overall 30-day and six-month survival after VAD placement, survival to transplantation, and survival one year post-transplantation were similar to patients without severe renal dysfunction.

CONCLUSIONS

Contemporary use of VAD leads to resolution of severe renal dysfunction in most cardiogenic shock patients and comparable long-term outcomes to patients without renal dysfunction.

Bridge to transplant with the HeartMate device

The incidence and prevalence of chronic heart failure continues to increase, with an estimated 400,000 new cases per year in the United States. Cardiac transplantation is an effective therapy but is severely limited to approximately 2300 patients per year due to the donor shortage. With ever increasing waiting times, a significant number of patients become severely debilitated or expire prior to transplantation. A mechanical circulatory support device was first used as a "bridge to transplantation" in 1969. Since then, mechanical devices have increased tremendously in reliability and efficaciousness. The HeartMate left ventricular assist device (LVAD) has been utilized extensively in a bridge to transplant application with excellent results. Patients refractory to aggressive medical management can be sustained reliably until transplantation. In addition, bridging allows for the correction of physiologic and metabolic dearrangements often seen in these severely ill patients prior to transplantation. Nutritional, economic, and quality-of-life issues also favor earlier LVAD placement in refractory patients. This reportsummarizes the overall bridging experience with the HeartMate LVAD and focuses on our experience with this device at Rush-Presbyterian-St. Luke's Medical Center.

Multicenter clinical evaluation of the HeartMate vented electric left ventricular assist system in patients awaiting heart transplantation

BACKGROUND

Despite advances in heart transplantation and mechanical circulatory support, mortality among transplant candidates remains high. Better ways are needed to ensure the survival of transplant candidates both inside and outside the hospital.

METHODS

In a prospective, multicenter clinical trial conducted at 24 centers in the United States, 280 transplant candidates (232 men, 48 women; median age, 55 years; range, 11-72 years) unresponsive to inotropic drugs, intra-aortic balloon counterpulsation, or both, were treated with the HeartMate Vented Electric Left Ventricular Assist System (VE LVAS). A cohort of 48 patients (40 men, 8 women; median age, 50 years; range, 21-67 years) not supported with an LVAS served as a historical control group. Outcomes were measured in terms of laboratory data (hemodynamic, hematologic, and biochemical), adverse events, New York Heart Association functional class, and survival.

RESULTS

The VE LVAS-treated and non-VE LVAS-treated (control) groups were similar in terms of age, sex, and distribution of patients by diagnosis (ischemic cardiomyopathy, idiopathic cardiomyopathy, and subacute myocardial infarction). VE LVAS support lasted an average of 112 days (range, < 1-691 days), with 54 patients supported for > 180 days. Mean VE LVAS flow (expressed as pump index) throughout support was 2.8 L x min(-1) x m(-2). Median total bilirubin values decreased from 1.2 mg/dL at baseline to 0.7 mg/dL (P =.0001); median creatinine values decreased from 1.5 mg/dL at baseline to 1.1 mg/dL (P =.0001). VE LVAS-related adverse events included bleeding in 31 patients (11%), infection in 113 (40%), neurologic dysfunction in 14 (5%), and thromboembolic events in 17 (6%). A total of 160 (58%) patients were enrolled in a hospital release program. Twenty-nine percent of the VE LVAS-treated patients (82/280) died before receiving a transplant, compared with 67% of controls (32/48) (P <.001). Conversely, 71% of the VE LVAS-treated patients (198/280) survived: 67% (188/280) ultimately received a heart transplant, and 4% (10/280) had the device removed electively. One-year post-transplant survival of VE LVAS-treated patients was significantly better than that of controls (84% [158/188] vs 63% [10/16]; log rank analysis P =.0197).

CONCLUSION

The HeartMate VE LVAS provides adequate hemodynamic support, has an acceptably low incidence of adverse effects, and improves survival in heart transplant candidates both inside and outside the hospital. The studies of the HeartMate LVAS (both pneumatic and electric) for Food and Drug Administration approval are the only studies with a valid control group to show a survival benefit for cardiac transplantation.

Cardiac transplant outcome of patients supported on left ventricular assist device vs. intravenous inotropic therapy

BACKGROUND

Although the left ventricular assist device (LVAD) has been increasingly used as a bridge to transplant, its effect on post-transplant outcome is uncertain. We, therefore, designed this study using the Cardiac Transplant Research Database to compare patients supported on an LVAD before transplant with those treated with intravenous inotropic medical therapy.

METHODS AND RESULTS

Of the 5,880 patients transplanted between 1990 and 1997, a total of 502 received support from LVADs and 2,514 received intravenous inotropic medical therapy at the time of transplant. Kaplan-Meier analysis showed no significant difference in post-transplant survival between the LVAD and medical-therapy groups (p = 0.09). Results of a multivariate Cox regression analysis were consistent with that of the Kaplan-Meier analysis and did not identify LVAD as a significant risk factor for mortality. The percentage of patients who received LVADs as a function of total transplants increased from 2% in 1990 to 16% in 1997. Furthermore, although the number of extracorporeal LVADs remained relatively constant, the number of intracorporeal LVADs increased over time. Multivariate parametric analysis found that the risk factors for post-transplant death in the LVAD group were extracorporeal LVAD use (p = 0.0004), elevated serum creatinine (p = 0.05), older donor age (p = 0.03), increased donor ischemic time (p < 0.0001), and earlier year of transplant (p = 0.03).

CONCLUSIONS

Given a limited donor supply, the intracorporeal LVAD helps the sickest patients survive to transplant and provides post-transplant outcome similar to that of patients supported on inotropic medical therapy. Therefore, patients supported on LVADs before transplant may receive the greatest marginal benefit when compared with other transplant candidates.

Research and development of an implantable, axial-flow left ventricular assist device: the Jarvik 2000 Heart

Advances in technology and increased clinical need have led to the development of a new type of blood pump. The Jarvik 2000 Heart is an electrically powered, axial-flow left ventricular assist device that has been developed during the past 13 years. Unlike first-generation left ventricular assist devices, which were developed in the 1970s and were designed to totally capture the cardiac output, the Jarvik 2000 is designed to normalize the cardiac output by augmenting the function of the chronically failed heart for extended periods. Design iterations have been tested in 67 animals, and clinical trials have recently begun. Three patients have received the Jarvik 2000 as a bridge to transplantation, and 1 patient is being supported permanently outside the hospital. All 4 patients have improved from New York Heart Association functional class IV to class I, and 2 of them have been discharged from the hospital after heart transplantation. The experimental and clinical results indicate that the Jarvik 2000 can provide physiologic support with minimal complications and is reliable, biocompatible, and easy to implant.

Left ventricular assist device implantation: short and long-term surgical complications

Long-term implanted left ventricular assist devices (LVADs) have significantly improved the care of patients awaiting heart transplantation and will provide an alternative therapy to select patients with heart failure. However, although the technology and clinical results continue to improve, LVAD implantation is still associated with a significant level of complications. Left ventricular assist device-associated complications can be broadly divided by their temporal occurrence. Early complications include perioperative hemorrhage, air embolism, and right ventricular failure. Beyond the perioperative period, late complications consist primarily of infection, thromboembolism, and primary device failure. An improved understanding of the mechanisms involved should aid the clinician in further reducing the incidence of these occurrences.

Left ventricular assist device as a bridge to patient and myocardial recovery

This article reviews the effects of chronic left ventricular assist device implantation on functional changes in patients with end-stage heart disease. Functional recovery can be measured by using response to exercise, quality-of-life surveys, improvements in noncardiac organ function, or changes in metabolic and neurohormonal levels. Recovery in intrinsic function of the heart can be assessed by changes in cardiac pump function or in baseline histological or biochemical abnormalities. Improvements in all of these areas have been found, although many reported studies are limited by a small sample size from selected subsets of patients rather than consecutive series.

Plasma exchange for hyperbilirubinemia following implantation of a left ventricle assist system: a case report

A 49-year-old patient with end-stage dilated cardiomyopathy underwent implantation of a left ventricular assist system (LVAS). Although the systemic circulation seemed to be improved, the serum total bilirubin (Tbili) level increased sharply in the early postoperative period (preoperative Tbili, 5.7 mg/dl; postoperative day 3, 33.6 mg/dl). Plasma exchange (PE) was performed 7 times from postoperative day 4, and the Tbili level decreased to 16.3 mg/dl by postoperative day 11. Thereafter, serum Tbili normalized concomitant with improved circulatory condition. The cause of the hyperbilirubinemia was considered to be temporary right ventricular dysfunction or hepatic sinusoid endothelial dysfunction. The liver function was recoverable, so PE had been effective in this case. Unfortunately, the patient suffered a midbrain infarction and ultimately died. From this experience, PE is recommended if it is judged that liver function can be preserved and circulation is adequate, but its implementation should not be delayed. It is essential that LVAS is implanted before damage occurs to end-organ function and thus prevent hyperbilirubinemia.

Outcome of patients with ventricular assist devices and acute renal failure requiring renal replacement therapy

The significance of acute renal failure (ARF) for patients treated with a ventricular assist device (VAD) is uncertain. There is little information on the outcome of patients who require renal replacement therapy during treatment with a VAD. A retrospective review was undertaken to evaluate the impact of renal failure requiring renal replacement therapy on such patients. Studied were 227 patients who were supplied with a VAD at the German Heart Institute Berlin. Fifty-five patients required renal replacement therapy during treatment with a VAD. These were compared with patients not needing renal replacement therapy (ARF and non-ARF groups). Significant differences for the end points of survival, heart transplantation, and discharge from hospital were observed in patients with ARF (p < 0.01). Survival was then analyzed according to indications for treatment with a VAD (bridge to transplantation or cardiac recovery after cardiotomy, transplantation, myocardial infarction, myocarditis, and endocarditis). Survival for bridge-to-transplantation patients was clearly influenced in a negative way by ARF (p < 0.01). For cardiac recovery patients, only a small difference in survival was observed (p = 0.05). We conclude that ARF is a negative predictor for bridge-to-transplantation patients. For cardiac recovery patients the impact of ARF on survival is marginally significant.

Comparison of functional capacity in patients with end-stage heart failure following implantation of a left ventricular assist device versus heart transplantation: results of the experience with left ventricular assist device with exercise trial

BACKGROUND

Use of a permanent left ventricular assist device (LVAD) has been proposed as an alternate treatment of patients with end-stage heart failure. The purpose of this study was to compare the functional capacity of patients following implantation of a LVAD vs heart transplant (HTx).

METHODS

Eighteen patients from 6 centers who received an intracorporeal LVAD as a bridge to HTx underwent treadmill testing 1 to 3 months post-LVAD and again post-HTx. Baseline and peak measurements, including oxygen consumption, blood pressures, and respiratory rate were made during each treadmill test.

RESULTS

Peak oxygen consumption was 14.5+/-3.9 ml/kg/minute post-LVAD and 17.5+/-5.0 ml/kg/minute post-HTx (p < .005). The percentage of the predicted peak oxygen consumption based on gender, weight, and age was 39.5%+/-5.5% post-LVAD and 47.7%+/-10.9% post-HTx (p < .005). Exercise duration was lower post-LVAD than post-HTx (10.3+/-4.2 minute vs 12.5+/-5.4 minute, p < .05). After LVAD implantation, peak total oxygen consumption correlated with peak LVAD rate and output. Eight patients reached an LVAD rate of 120 beats per minute (bpm) before the conclusion of exercise, the maximum rate for the outpatient electric device. The peak respiratory exchange ratio post-LVAD was 1.15+/-0.22 and post-HTx was 1.15+/-0.18, consistent with a good effort in both groups.

CONCLUSIONS

Patients demonstrated a lower functional capacity post-LVAD than post-HTx. For some patients functional capacity post-LVAD may be improved by a higher maximum LVAD rate and output.

Left ventricular assist system as a bridge to myocardial recovery

BACKGROUND

Despite recent advances in medical therapy, heart transplantation, and mechanical circulatory support, the mortality of patients with congestive heart failure remains high.

METHODS

Retrospective data on 5 patients were obtained from our hospital's medical records. Each patient was supported by a left ventricular assist system (LVAS) because of severe congestive heart failure. The duration of LVAS support averaged 229 days (range, 46 to 447 days). In 3 patients, the LVAS was removed electively after the patient showed recovery of myocardial function. In the other 2, it was removed because of a malfunction.

RESULTS

In response to LVAS support, hemodynamic variables were significantly improved. The mean cardiac index increased from 1.45 to 2.69 L x min(-1) x m(-2) (p < 0.001) and the mean left ventricular ejection fraction increased from 0.144 to 0.288 (p < 0.025). All patients were in New York Heart Association functional class IV at LVAS implantation and class I at its explantation. One patient died of noncardiac-related causes 10 days after LVAS removal. The remaining 4 patients are alive and well 35, 33, 14, and 2 months after LVAS removal.

CONCLUSIONS

In select patients with severe congestive heart failure, mechanical unloading with an LVAS can result in recovery of myocardial function. These patients can return to a normal physical status, thereby avoiding heart transplantation. More research is required to determine optimal modes of LVAS support, to predict which patients are likely to recover, and to assess long-term outcomes.

Exercise performance and chronotropic response in heart failure patients with implantable left ventricular assist devices

During metabolic stress testing, 9 of 20 patients with left ventricular assist devices exhibited a lag in peak device rate by < or = 85% of peak native heart rate (group I), with peak device rates of 118 +/- 9 beats/min compared with group II, in which peak device rate nearly equaled peak native rates. Peak systolic blood pressure was significantly greater in group II than group I, but there was no significant difference in peak oxygen consumption, anaerobic threshold, or peak flows.

Inflow valve regurgitation during left ventricular assist device support may interfere with reverse ventricular remodeling

BACKGROUND

Left ventricular assist devices have been reported previously to reverse ventricular remodeling in patients with dilated cardiomyopathy. In patients with prolonged mechanical support, structural failure of the left ventricular assist device inflow valve can cause regurgitation into the left ventricle, which may affect adversely this process.

METHODS

Left ventricular end-diastolic pressure-volume relation of hearts explanted from 8 patients with left ventricular assist device and 8 control subjects with idiopathic cardiomyopathy was determined ex vivo at the time of transplantation.

RESULTS

Duration of mechanical support ranged from 210 to 276 days (mean +/- standard deviation = 283 +/- 76 days) in 3 patients with inflow valve regurgitation versus 100 to 155 days (132 +/- 22 days) in 5 patients without (p = 0.005). The end-diastolic pressure-volume relation of all hearts supported mechanically was shifted to the left toward normal controls. This effect was markedly attenuated in patients with inflow valve regurgitation.

CONCLUSIONS

Mechanical assistance can cause reverse remodeling in patients with dilated cardiomyopathy as evidenced by the shift in the end-diastolic pressure-volume relation curve to the left. Inflow valve failure, associated with prolonged support, can attenuate changes in left ventricular structure and dimension. Ineffective pressure and volume unloading may explain these observations.

Effects of exercise during long-term support with a left ventricular assist device. Results of the experience with left ventricular assist device with exercise (EVADE) pilot trial

BACKGROUND

Long-term implantation of a left ventricular assist device (LVAD) may be a future alternative treatment for end-stage heart failure. The objective of the present study was to determine the hemodynamic effects of supine bicycle exercise and functional capacity during upright treadmill exercise in 10 patients after LVAD implantation placed for refractory heart failure as a bridge to cardiac transplantation.

METHODS AND RESULTS

With supine bicycle exercise, 46 +/- 25 days after device placement, heart and LVAD rates increased in parallel from 87 +/- 12 to 117 +/- 14 bpm and 82 +/- 18 to 107 +/- 21 bpm, respectively. Peak O2 consumption was 8.2 +/- 1.7 mL O2.kg-1.min-1. Fick Systemic blood flow rose from 5.0 +/- 1.2 to 7.8 +/- 2.5 L/min. Right atrial and pulmonary capillary wedge pressures increased from 6 +/- 4 and 5 +/- 3 mm Hg to 12 +/- 5 and 13 +/- 8 mm Hg, respectively. End-diastolic left ventricular dimension increased from 3.9 +/- 1.3 to 4.8 +/- 1.6 cm; however, right ventricular dimension decreased from 3.2 +/- 1.0 to 2.3 +/- 0.9 cm. With upright treadmill exercise, peak O2 consumption was 14.1 +/- 2.9 mL O2.kg-1.min-1.

CONCLUSIONS

This study indicates that exercise during long-term LVAD support is safe and is not limited by right heart decompensation. It also justifies a larger study to examine how exercise after LVAD implantation compares with that after cardiac transplantation.

The continuing evolution of mechanical ventricular assistance

A great number of patients suffer and die of the sequelae of acute and chronic heart failure each year. Although advances in medical and surgical therapy have benefited many of these patients, most have disease that is refractory to any definitive therapy. For these patients cardiac transplantation is the only remaining hope. Unfortunately, because of the increasing demand for donor organs in the face of a fixed and limited supply, this option is available to only a small percentage of these patients. Even in patients accepted for transplantation, a significant waiting list mortality has been observed. A variety of VADs have been developed since the first successful case of mechanical cardiac assistance more than 30 years ago. These devices differ in basic mechanical function, method of insertion, and degree of implantability and thus have different indications and potential applications. Whereas the intraaortic balloon pump and centrifugal pumps are effective short-term support modalities, extracorporeal and implantable pulsatile devices have been used successfully for long-term support of patients with reversible and nonreversible cardiac failure. Although these pumps have most commonly been used as bridges to transplantation, increasing clinical experience has supported the notion of long-term mechanical assistance as a definitive therapy for patients with end-stage heart disease. Although complications, particularly infection and thromboembolism, pose significant challenges and long-term device reliability remains to be fully determined, available implantable devices appear to be capable of providing effective long-term support. As data are obtained from currently ongoing trials comparing VAD support with medical therapy for end-stage heart failure, ethical and economic issues will assume increasing importance.

Dialytic Support in Patients with Acute Renal Failure with Implantable Left Ventricular Assist Devices

The left ventricular assist device (LVAD), used thus far as a bridge to heart transplantation, may offer an alternative to heart transplantation. Because patients receiving LVADs are in cardiogenic shock, many experience acute ischemic renal failure in the peri-implantation period. We describe 10 patients who underwent dialysis after receiving LVADs for end-stage heart disease. Among 37 patients who received an LVAD, 10 required dialytic support (8 men, 2 women; mean age, 47.3 ± 11.3 yr; mean APACHE II score at ICU admission, 18.0 ± 4.7). Renal replacement therapy was started for fluid removal within 48 hours of LVAD implantation in 8 patients. Continuous renal replacement therapy (CRRT) was the first-line modality for 9 patients, including 3 slow continuous ultrafiltrations (SCUF), 4 continuous venovenous hemofiltrations (CWH), 5 continuous venovenous hemodiafiltrations (CWHD), 2 continuous arteriovenous hemofiltrations (CAVH), and 1 continuous arteriovenous hemodiafiltration (CAVHD). Patients remained on CRRT for a mean of 14.4 ± 6.1 days, and 5 were eventually changed to intermittent hemodialysis. The mean time on renal replacement therapy was 27.8 ± 19.7 days. During CRRT, despite daily average ultrafiltration of 3,445 ± 623 mL, net fluid loss was only 358 ± 507 mL/day. Metabolic control achieved with CRRT, expressed as mean ± SD, was: BUN 75.5 ± 13.0 mg/dL (26.9 ± mmol/L), serum creatinine 4.0 ± 0.7 mg/dL (354 ± 62 mmol/L), carbon dioxide content (bicarbonate plus dissolved CO2) 21.5 ± 1.7 mEq/L, and serum electrolytes within normal limits. Survival for patients with LVADs who did not require dialysis was 93% compared with 40% for the group with combined LVADs and dialytic support. The 4 patients who survived in the dialysis group all recovered renal function, and their need for dialysis ceased within 18 to 33 days. Mean serum creatinine levels at follow-up after transplantation were 2.0 ± 1.0 mg/dL (177 ± 88 mmol/L). In conclusion, CRRT provides good metabolic control and allows large ultrafiltration volume in patients supported by an implantable LVAD. We observed a 40% survival rate in patients with combined LVADS and dialytic support, and the survivors all recovered renal function.

Implantable LVAD infections: implications for permanent use of the device

BACKGROUND

Infection in implantable left ventricular assist device (LVAD) patients is common and has serious implications regarding permanent use of the LVAD.

METHODS

Thirty-three patients had HeartMate LVAD insertion as a bridge to heart transplantation. The mean length of hospital stay was 8 days before LVAD insertion. Before insertion 6 patients (18%) had positive pulmonary cultures and 5 patients (15%) had bacteremia.

RESULTS

During LVAD support 18 patients (55%) had bloodstream infection. Of 24 patients (73%) successfully bridged to transplantation, 12 (50%) had positive blood cultures including Staphylococcus species (n = 9), Candida (n = 3), Pseudomonas (n = 2), and Enterococcus (n = 2). Infectious complications encountered in this series included driveline infection requiring surgical revision, septic embolus, "cleared" device infection, "suppressed" device infection, and LVAD infection treated by device removal in 1 patient and device exchange in another.

CONCLUSIONS

Infection in implantable LVAD patients is common, especially in patients in whom multiple organ failure develops, requiring prolonged stay in the intensive care unit. Strategies are needed to prevent these infections in recipients of the permanent LVADs because treatment of an established infection is difficult and expensive.

Structural and left ventricular histologic changes after implantable LVAD insertion

Long-term support on the implantable left ventricular assist device (LVAD) produces structural changes in the recipient's heart. To assess the possibility of heart "recovery" we reviewed the records of 19 HeartMate LVAD recipients to determine structural and left ventricular histologic changes during LVAD support. Intraoperative transesophageal echocardiographic studies were performed in the operating room before LVAD insertion, immediately after LVAD insertion, and at explantation and heart transplantation (mean duration of support, 76 +/- 34 days). The initiation of LVAD pumping led to an immediate decrease (p < 0.001) in left ventricular dimensions, which were not significantly different by the time of device explantation. Left ventricular fractional shortening did not significantly improve during LVAD support (0.07 +/- 0.03 before LVAD; 0.11 +/- 0.10 immediately after LVAD; 0.11 +/- 0.11 before explantation). Histologic specimens showed a significant reduction in the number of wavy fibers, and contraction band necrosis (p < 0.01), both markers of acute myocyte damage. However, myocardial fibrosis increased (p < 0.05). Myocyte diameter increased slightly (p = 0.07). We conclude that implantable LVAD support is associated with immediate changes in ventricular structure. Histologic markers of acute myocyte damage improve, but fibrosis increases. Because the structural changes occur immediately, they do not indicate "recovery" of left ventricular function, but merely changes in loading conditions.

Hemodynamic and physiologic changes during support with an implantable left ventricular assist device

To evaluate hemodynamic effectiveness and physiologic changes on the HeartMate 1000 IP left ventricular assist device (Thermo Cardiosystems, Inc., Woburn, Mass.), we studied 25 patients undergoing bridge to heart transplantation (35 to 63 years old, mean 50 years). All were receiving inotropic agents before left ventricular assist device implantation, 21 (84%) were supported with a balloon pump, and 7 (28%) were supported by extracorporeal membrane oxygenation. Six patients died, primarily of right ventricular dysfunction and multiple organ failure. Nineteen (76%) were rehabilitated, received a donor heart, and were discharged (100% survival after transplantation). Pretransplantation duration of support averaged 76 days (22 to 153 days). No thromboembolic events occurred in more than 1500 patient-days of support with only antiplatelet medications. Significant hemodynamic improvement was measured (before implantation to before explantation) in cardiac index (1.7 +/- 0.3 to 3.1 +/- 0.8 L/min per square meter; p < 0.001), left atrial pressure (23.7 +/- 7 to 9 +/- 7.5 mm Hg; p < 0.001), pulmonary artery pressure, pulmonary vascular resistance, and right ventricular volumes and ejection fraction. Both creatinine and blood urea nitrogen levels were significantly higher before implantation in patients who died while receiving support. Renal and liver function returned to normal before transplantation. We conclude that support with the HeartMate device improved hemodynamic and subsystem function before transplantation. Long-term support with the HeartMate device has a low risk of thromboemboli and makes a clinical trial of a portable HeartMate device a realistic alternative to medical therapy.

HeartMate implantable left ventricular assist device: bridge to transplantation and future applications

The HeartMate implantable left ventricular assist device (LVAD) is approaching the time when it will be implanted permanently. Experience with the HeartMate 1000 IP LVAD at the Cleveland Clinic as a bridge to heart transplantation in 21 patients has shown (1) excellent hemodynamic function [improving cardiac index from a mean +/- standard deviation of 1.6 +/- 0.26 L.min-1.m-2 to 3.0 +/- 0.42 L.min-1.m-2]; (2) 81% survival before transplantation with a mean duration of 64 +/- 34 days of LVAD support; (3) 100% survival after transplantation; (4) New York Heart Association class IV and moribund patients were returned to class I or II status while on the LVAD; and (5) a remarkably low risk of thromboemboli during 1,583 patient-days of support. The multicenter experience (173 patients) confirms the low risk of embolic events (2%, including septic emboli). A "target population" for initial use of the permanent device was outlined from a retrospective review of 570 patients. A subgroup of 74 patients (13%) were between 18 and 75 years of age, had isolated cardiac failure (without multiple comorbidities), and required inotropic medications, intraaortic balloon pump support, or both. Survival for this patient group (mean age, 57 +/- 13 years; 68% male) was poor: median survival was 7 months, 21.6% died during the hospitalization, and 47.3% died after discharge. Of the survivors, only 4 patients (5% of the initial 74 patients) were in New York Heart Association class I. From the bridge-to-transplantation experience we extrapolate that survival and quality of life should improve for patients in the target population treated with the portable LVAD.(ABSTRACT TRUNCATED AT 250 WORDS)