Ventricular assist device use with mechanical heart valves: an outcome series and literature review

Long-term left ventricular support in patients with a mechanical aortic valve

OBJECTIVES

The presence of a mechanical prosthesis has been regarded as an increased risk of thromboembolic complications and as a relative contraindication for a left ventricular assist device (LVAD). Five patients in our center had a mechanical aortic valve at the time of device implantation and were studied regarding thromboembolic complications.

DESIGN

Five patients operated upon with an LVAD (1 HeartMate I™, 4 HeartMate II™) between 2002 and 2011 had a mechanical aortic valve at the time of implantation. The first patient had a patch closure of the aortic valve. In four patients, the prosthesis was left in place. Anticoagulants included aspirin, warfarin, and clopidogrel.

RESULTS

The average and accumulated treatment times were 150 and 752 days, respectively. Three of the five patients showed early signs of valve thrombosis on echo with concomitant valve dysfunction. Four patients were transplanted without thromboembolic events during pump treatment. One patient died from a hemorrhagic stroke after 90 days on the LVAD.

CONCLUSIONS

The strategy of leaving a mechanical heart valve in place at the time of LVAD implantation in five patients led to valvular thrombosis in three but did not provoke embolic events. It increased the complexity of postoperative anticoagulation.

Aortic valve pathophysiology during left ventricular assist device support

The increased applicability and excellent results with left ventricular assist devices (LVADs) have revolutionized the available treatment options for patients with advanced heart failure. Pre-existing valve abnormalities are common in this population, and subsequent development of valve abnormalities after LVAD placement is also often noted. Although native mitral and tricuspid valve disease is more common in heart failure patients before LVAD placement, aortic valves are much more likely to generate abnormal pathophysiology in the LVAD patient during as well as after LVAD placement. The aim of this comprehensive review is to review aortic valve function in LVAD patients and highlight the consideration of pre-existing valve disease on patient treatment at the time of LVAD implant. The basis for structural changes leading to valve pathophysiology during and after LVAD placement will be described, providing a basis for improved clinical understanding and new strategies to prevent these conditions.

Mechanical mitral prosthesis with a short-term left ventricular assist device

Mechanical circulatory support with ventricular assist devices in patients with mechanical valvular prostheses may predispose to thromboembolic and hemodynamic complications. Conventional approaches to reduce these risks involve redo valve replacement to a bioprosthesis. Careful management of the ventricular assist device to allow flow across the prosthesis may obviate the need for redo valve replacement. Avoidance of further myocardial ischemia during redo valve replacement carries particular importance for patients in whom the aim is recovery. We report a successful outcome from retention of a mechanical mitral prosthesis during a 10-day period of mechanical circulatory support and review the pertinent literature.

Axial Flow Pump Support in a Marfan Patient With an Aortic Mechanical Heart Valve

The presence of a mechanical heart valve in the aortic position is usually considered a contraindication for the use of cardiac assist devices. Only a few cases with the combination of mechanical circulatory support and valve prostheses have been reported in the literature to date, and the experience is even more limited in the new generation of miniaturized axial flow pumps. We present a case report of a patient with a mechanical aortic heart valve who was successfully supported with a continuous flow pump and discuss the literature available on this problem. Further on, the patient was weaned from his ventricular assist device after 456 days of support.

Levosimendan may improve survival in patients requiring mechanical assist devices for post-cardiotomy heart failure

INTRODUCTION

Most case series suggest that less than half of the patients receiving a mechanical cardiac assist device as a bridge to recovery due to severe post-cardiotomy heart failure survive to hospital discharge. Levosimendan is the only inotropic substance known to improve medium term survival in patients suffering from severe heart failure.

METHODS

This retrospective analysis covers our single centre experience. Between July 2000 and December 2004, 41 consecutive patients were treated for this complication. Of these, 38 patients are included in this retrospective analysis as 3 patients died in the operating room. Levosimendan was added to the treatment protocol for the last nine patients.

RESULTS

Of 29 patients treated without levosimendan, 20 could be weaned off the device, 9 survived to intensive care unit discharge, 7 left hospital alive and 3 survived 180 days. All 9 patients treated with levosimendan could be weaned, 8 were discharged alive from ICU and hospital, and 7 lived 180 days after surgery (p < 0.002 for 180 day survival). Plasma lactate after explantation of the device was significantly lower (p = 0.002), as were epinephrine doses. Time spent on renal replacement therapy was significantly shorter (p = 0.023).

CONCLUSION

Levosimendan seems to improve medium term survival in patients failing to wean off cardiopulmonary bypass and requiring cardiac assist devices as a bridge to recovery. This retrospective analysis justifies prospective randomised investigations of levosimendan in this group of patients.

Patient selection for assist devices: bridge to transplant

Patients in severely progressed states of heart failure can be bridged to successful heart transplantation with mechanical assist devices. Experience has demonstrated that patient selection and timing of device implantation are crucial for obtaining acceptable results when using this expensive technology. The degree of irreversible secondary organ dysfunction before re-establishing adequate cardiac output determines the chance of reaching transplantation. Patients who recover during support from all sequelae of end stage heart failure have an excellent outcome after heart transplantation.

Management of acute cardiogenic shock

The present state of the art in mechanical cardiac assist technology has permitted application of machines to a variety of conditions that confound the cardiologist and cardiac surgeon alike. Decades of research and development have allowed the present devices to be used as bridges to native heart recovery and bridges to transplantation. We are now entering the era in which devices are being placed for permanent assist or replacement. Although the acute cardiogenic shock patient remains problematic, we now have at our disposable a variety of tools that have enabled us to salvage more patients than ever before. The experience with these systems continues to grow, with leading centers and investigators contributing meaningful information toward the application and development of the latest technologies. It has been said that mechanical therapies precede biological therapies. We are at the crossroads in which a combination of biological therapies with mechanical therapies is underway. Current research is investigating the role of mechanical cardiac support while biological therapies are introduced into the failing heart. In the meantime, the role of mechanical cardiac assist and replacement has matured into an effective means of treating acute cardiogenic shock of any variety.