Permanent ventricular assist device support versus cardiac transplantation

Characteristics and Outcomes of Patients Bridged to Cardiac Transplantation on Centrifugal Ventricular Assist Devices: A Case Series of the Early Experience of One Canadian Transplant Centre

BACKGROUND

Centrifugal ventricular assist devices (VADs) have been used successfully to bridge patients in cardiogenic shock to cardiac transplantation, though complications are frequent and often life-threatening.

PURPOSE

To describe characteristics and examine outcomes of patients bridged to cardiac transplantation on centrifugal VADs.

METHODS

A retrospective health record review was conducted on all adults over a 12 year period (N=20) placed on centrifugal VADs with the intent to bridge to cardiac transplantation at a major Canadian transplant centre.

RESULTS

Complications of VAD support necessitated removal of 12 patients from the transplant list; seven (35%) survived to cardiac transplantation. Of the seven recipients, five survived to discharge and four remain alive and well.

CONCLUSIONS

Bridging patients on centrifugal VADs to cardiac transplantation requires improvement, including maintaining patient stability during the period of early VAD institution, aggressively managing complications of VAD support, and consideration of long-term pulsatile devices. However, if patients survive to transplantation, good long-term outcomes are expected.

Short-term in vivo studies of surface thrombosis in a left ventricular assist system

Thrombosis continues to be a major adverse and at times fatal event in patients with left ventricular assist systems (LVAS). To assess acute thrombosis in an LVAS, multiscale analysis of surface thrombosis was performed on LVAS blood sacs retrieved after implantation in seven calves for 3 days. Two study groups were evaluated: One group was given heparin and warfarin sodium throughout the study; the second received no postoperative anticoagulation. On explantation, the blood sacs were examined for macroscopic thrombi; microscale thrombosis was assessed with the use of scanning electron microscopy. Macroscopic thrombi about 1 mm in diameter were seen in all sacs from both groups. Although macroscopic thrombi occurred in all sac regions, scanning electron microscopy revealed differences in microscale topography between the port regions and the other sac regions. The primary structure was spherical particles approximately 400 nm in diameter, found to occur at a lower density in the ports. In contrast, the highest densities of proteinaceous rough topography and fibrillar structures consistent with fibrin clot were seen in the port regions. The density distribution of these structures was different in the eight sac regions, and anticoagulation therapy appeared to have no effect on surface thrombosis in these short-term LVAS implants.

Heart transplant and left ventricular assist device costs

BACKGROUND

With the increasing clinical success of left ventricular assist devices (LVADs), physicians need to measure device cost efficacy to determine the societal value of this technology. Today's large clinical volume allows comparison of the costs of this innovation as compared with orthotopic heart transplant (OHT).

METHODS

We evaluated hospital cost and reimbursement for patients who were discharged after LVAD implantation and returned to the hospital for OHT. To control for patient-specific variables, LVAD therapy and OHT therapy were compared in the same patient; that is, only those patients who received an LVAD were discharged, and returned for OHT were studied. Length of stay (LOS), re-admissions and outpatient services were analyzed, including their respective total actual hospital cost (TAHC) and net revenue (NR). Time periods analyzed were the same for LVAD and OHT.

RESULTS

From the LVAD population at Columbia-Presbyterian Medical Center, 36 patients were discharged following HeartMate vented electric (VE) implantation and re-admitted for OHT between December 1996 and June 2000. Mean pre-LVAD implantation LOS was 21.3 +/- 24.1 days. Post-LVAD LOS was 36.8 +/- 22.2 days vs 18.2 +/- 12.2 days post-OHT (p < 0.001). Mean length of LVAD support was 123.4 +/- 77.7 days. Overall total costs for LVADs exceeded that of OHT, whereas revenue was relatively lower. TAHC post-LVAD averaged $197,957 +/- 77,291, whereas TAHC post-OHT averaged $151,646 +/-53,909 (p = 0.005). NR averaged $144,756 +/- 96,656 post-LVAD vs $178,562 +/- 68,571 post-OHT (p = 0.09). LVAD patients had more re-admissions compared with OHT: 1.2/123 days (+/- 1.7) vs 0.3/123 days (+/- 0.6), respectively (p = 0.005). The average LOS during a re-admission was similar between the 2 groups (LVAD 5.6 days [+/- 10.6] vs OHT 9.6 days [+/- 8.2]; p = 0.18). OHT was associated with a significantly greater number of outpatient services compared with LVAD (9.7 [+/- 6.1] vs 3.0 [+/- 4.7]; p < 0.001). In contrast to OHT, revenues did not match the costs of LVAD therapy.

CONCLUSIONS

LVAD implantation is associated with longer LOS and higher cost for initial hospitalization compared with OHT. LVAD patients have higher re-admission rates compared with OHT but similar costs and LOS. OHT is associated with a greater number of outpatient services. Reimbursements for LVAD therapy are relatively low, resulting in significant lost revenue. If LVAD therapy is to become a viable alternative, improvements in both cost-effectiveness and reimbursement will be necessary.

Multiscale analysis of surface thrombosis in vivo in a left ventricular assist system

Thrombosis limits the success of ventricular assist devices as the demand for alternatives to heart transplants is increasing. This study mapped the occurrence of thrombosis in a left ventricular assist system (LVAS) to better understand the biologic response to these devices. Nine calves divided into two groups were implanted with LVAS for 28 to 30 days. One group was anticoagulated, whereas the second group received no long-term anticoagulation. The blood-contacting poly(urethane urea) surfaces of blood sacs in the LVAS were examined for macroscopic thrombi upon retrieval. The sac was partitioned into eight sections and imaged for thrombi by scanning electron microscopy. No difference in thrombosis was observed macroscopically between the groups. Anticoagulation appeared to result in reduction of platelet-like structures, but the presence of fibrin-like structures remained similar between groups. Regional differences correlating with high and low shear stress regions were observed. At the macroscale, fewer thrombi were recorded in the high shear stress ports. At the microscale, features resembling fibrin were observed primarily in the ports and platelet-like features were common in lower shear stress regions. These variations in thrombosis with anticoagulation and location are likely due to varied fluid dynamics within the LVAS blood sac.

Mechanical assist devices as bridging systems to transplantation: A current review, possible risks, and perspectives

Mechanical circulatory support is of increasing interest because of its considerable demographic importance concerning myocardial failure and because of stagnant transplantation volumes. This study offers an overview of the present state of the art. Institutions with a mechanical circulatory assist program usually dispose of a decision chart for the various systems. There are devices with intra- or extracorporeal pump positions and with long- or short-term application. The various possibilities of mechanical circulatory assistance are presented, along with their technical properties, indications, and results. Currently, the application is concerned with technical reliability and limited biocompatibility with thrombembolic, neurological, and infectious complications. With some further developments, the present state of the art is supposed to enable a widespread application as bridging systems and as long-term therapy of heart failure within the next few years.

Bone marrow is a source of regenerated cardiomyocytes in doxorubicin-induced cardiomyopathy and granulocyte colony-stimulating factor enhances migration of bone marrow cells and attenuates cardiotoxicity of doxorubicin under electron microscopy

BACKGROUND

It has been reported previously that granulocyte colony-stimulating factor (GCSF) injection improves infarcted heart function, but the mechanism remains unclear. In this study we sought to determine whether GCSF-mobilized bone marrow cells could regenerate neo-myocardium and repair doxorubicin-induced cardiomyopathy.

METHODS

C57BL/6 mice were irradiated and bone marrow cells (BMC; 1 x 10(6)) from green fluorescent protein (GFP) mice (GFP-BMC) were transplanted intravenously, followed by splenectomy. Doxorubicin (2.5 mg/kg, 6 times for 2 weeks) was administered intraperitoneally 2 weeks later. GCSF (50 microg/kg/day for 8 days) was administered sub-cutaneously after doxorubicin injection (Group I, n = 11) and 3 weeks later (Group II, n = 8), and saline was injected in Group III animals (n = 8). Eight weeks after doxorubicin injection, the excised hearts were studied immunologically and electron microscopically.

RESULTS

Survival rates were 81.8% in Group I, 50.0% in Group II and 62.5% in Group III. The number of GFP-BMC in Group I (15.4 +/- 7.4 per high-power field) was highest (p < 0.05). In all groups, cardiac troponin I-positive cells derived from GFP-BMC were observed in the hearts. GFP-BMC in hearts stained positively against cardiac troponin I (4.3 +/- 2.5%), myosin heavy chain (5.0 +/- 4.3%), atrial natriuretic peptide (ANP; 3.9 +/- 2.4%) and connexin 43 (11.9 +/- 7.3%) in Group I. Myofibrils, mitochondria and fundamental architecture were almost all preserved in Group I, whereas hearts were severely damaged in Groups II and III.

CONCLUSIONS

Bone marrow was shown to be one of the sources of regenerated cardiomyocytes in the doxorubicin-induced cardiomyopathic heart. Early administration of GCSF enhanced the migration of bone marrow cells into the heart, and attenuated the cardiotoxicity of doxorubicin.

Cell-based Therapy to Regenerate Myocardium: from Bench to Bedside

The field of cell-based therapy to regenerate myocardium has been expanding rapidly, with significant advances being made in both the laboratory and the clinical area. In this article we review this field, including our experiences and discuss remaining issues and possibilities for future clinical applications.

Surgical management of patients in the REMATCH trial

The donor shortage makes cardiac transplantation a less than ideal treatment for end-stage heart failure. The utility of the left ventricular assist device (LVAD) as a permanent form of circulatory support has recently been established in the REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) trial. In this report, we describe the surgical management of LVAD patients in REMATCH and their short-term outcomes. Between 1998 and 2001, 129 patients with end-stage heart failure, who were excluded from consideration for transplantation, were enrolled in the REMATCH clinical trial. Patients were randomized to two treatment arms: optimal medical management or HeartMate vented electric LVAD implantation. The primary end point of the study was death from any cause. Secondary end points included the incidence of serious adverse events, the duration of hospitalization, quality of life, and functional status. Sixty-eight patients received an LVAD, 55 (81%) of whom survived for longer than 1 month. The median intensive care unit and hospital lengths of stay (LOS) for those that survived at least 1 month were 15 and 34 days, respectively. Sixty-seven (99%) patients had a serious adverse event. The rates of perioperative bleeding, late bleeding, right heart failure, and sepsis were 0.42, 0.53, 0.15, and 0.53 events/patient-year, respectively. Factors predictive of a longer LOS for the implant hospitalization included sepsis, age, and late bleeding (p < 0.0001). The patients' New York Heart Association functional class improved significantly at 1 month compared with base line (p < 0.001). Functional class improved in LVAD-supported patients despite a high adverse event rate. Most adverse events occurred within 30 days of device implantation. Sepsis, age, and late bleeding were the major determinants of LOS.

Costs and insurance coverage associated with permanent mechanical cardiac assist/replacement devices in the United States

Each year over 50,000 persons in the United States could potentially benefit from some form of permanent cardiac replacement or assistance. Approximately 7000 of these persons get on the waiting list for a transplant, and 2300 are transplanted. About 2000 patients are reportedly exposed to a mechanical cardiac assist device, most often as a bridge to transplant. The majority of persons who might benefit from cardiac replacement are never referred for treatment and, thus, the number of deaths on the waiting list is a misleading indicator of access to transplantation and overall patient mortality. The total economic burden associated with coronary artery disease and congestive heart failure now exceeds $140 billion each year, with approximately $700 million directly spent on heart transplant procedures alone. If a viable total artificial heart is devised to replace a failed heart, or a ventricular assist system to permanently assist a failing heart, direct aggregate expenditures alone are likely to be somewhere between $5.4 and $24.0 billion annually. Based on individual patient care costs, as well as aggregate national expenditures, insurers will be reluctant to pay for the permanent use of such devices, even though cost is reportedly not a consideration in coverage decisions. Today, medical benefits and added value are concepts that will shape the coverage determination process, as will increasingly liberal policies regarding payment for treatment costs in relationship to clinical trials. Nonetheless, resource allocation and rationing decisions loom large as strange "characters at play" on an international economic "stage," while being "directed" by worldwide health care needs.

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.

Autologous smooth muscle cell transplantation improved heart function in dilated cardiomyopathy

BACKGROUND

Transplantation of myocytes into scarred myocardium has been shown to inhibit ventricular remodeling and maintain myocardial contractility. However, the effect of cell transplantation on hearts with global rather than regional dysfunction is unknown. Therefore, we evaluated the effect of transplantation of autologous smooth muscle cells on the morphometry and function of dilated cardiomyopathic hearts.

METHODS

Smooth muscle cells were isolated from the ductus deferens of 13-week-old BIO 53.58 hamsters with dilated cardiomyopathy, and cultured for 4 weeks before transplantation. Smooth muscle cells (4 x 10(6) cells) or culture medium were injected into 17-week-old animals in the transplantation and control groups (n = 12 each), respectively. Prelabeling of the smooth muscle cells with 5-bromo-2'-deoxyuridine was performed before transplantation in a group of transplanted hamsters. Another group (sham, n = 12) underwent the operation but did not receive an injection either of smooth muscle cells or of culture medium. Four weeks after transplantation, heart function was evaluated in a Langendorff preparation.

RESULTS

Musclelike tissue, labeled with 5-bromo-2'-deoxyuridine, was found at the site of transplantation in the cell-transplanted animals. The cell-transplanted hearts were smaller (p < 0.001), and had greater developed pressures and maximum rate of increase of left ventricular pressure (both p < 0.001) than control and sham hearts. Control hamsters injected with culture medium did not differ from sham-operated animals.

CONCLUSIONS

Transplantation of autologous smooth muscle cells prevented cardiac dilatation and improved ventricular function in hamsters with dilated cardiomyopathy.

Cardiac transplantation: the final therapeutic option for the treatment of heart failure

End-stage heart failure is still associated with a decrease in quality and prognosis of life. Cardiac transplantation remains the final extraordinary therapeutic option for the treatment of truly irreversible end-stage heart failure in all age groups. The selection process of candidates and the acceptance of patients with relative contra-indications is characterized by the experience and skills of an interdisciplinary transplant team, which should have access to different mechanical circulatory support systems for short-term or long-term use: bridging to transplant as well as for recovery.