Intraoperative TandemHeart® Implantation as an Adjunct to High-Risk Valve Surgery

Abstract

Newer generations of assist devices for postcardiotomy support in patients with ventricular failure have eliminated bearings and incorporated suspended impellers, smaller cannulae and hardware, and simplified insertion techniques. We describe the use of a surgically implanted, percutaneous, continuous-flow centrifugal pump (the TandemHeart® percutaneous ventricular assist device) as part of a planned, pre-emptive approach for postcardiotomy support in a patient with severe mitral regurgitation, moderate tricuspid regurgitation, and biventricular failure. To our knowledge, this report documents the 1st use of a percutaneous ventricular assist device as an elective support device in a patient undergoing high-risk mitral or tricuspid valve surgery.

Temporary use of ventricular assist devices for postcardiotomy support in patients with severe biventricular failure is growing. Newer generation devices that eliminate bearings and use suspended impellers, smaller cannulae and hardware, and simplified insertion techniques have been introduced. The TandemHeart® percutaneous ventricular assist device (pVAD™) (CardiacAssist, Inc.; Pittsburgh, Pa) is a continuous-flow centrifugal pump that can deliver flows of up to 4 L/min. The device uses an inflow cannula that is inserted via the common femoral vein, across the atrial septum, and into the left atrium. The oxygenated left atrial blood is returned by way of a percutaneously placed cannula in the common femoral artery, thereby bypassing the left ventricle. The device has been used in myocardial infarction patients who have left ventricular failure and as a support device during high-risk percutaneous coronary interventions.^1,2 Herein, we describe the use of a surgically implanted TandemHeart as part of a pre-emptive plan for postcardiotomy support in a patient with severe mitral regurgitation, moderate tricuspid regurgitation, and biventricular failure.

Case Report

A 35-year-old woman with diabetes mellitus was admitted to our institution with dyspnea at rest, ascites, and peripheral edema. She had undergone coronary artery bypass grafting 3 years earlier and had required hemodialysis for 1 year before this admission. The patient had cirrhosis, as diagnosed by a prior liver biopsy.

Transthoracic echocardiography showed a left ventricular ejection fraction of 0.25, severe mitral regurgitation, and moderate-to-severe tricuspid regurgitation. The right ventricular function was diminished. Coronary angiography showed patent bypass grafts. The mean pulmonary artery pressure was 25 mmHg, the right atrial pressure was 16 mmHg, and the pulmonary artery wedge pressure was 25 mmHg. The patient was a high-risk surgical candidate because of respiratory and biventricular failure and multiple comorbidities; therefore, we decided to replace the mitral and tricuspid valves via a right thoracotomy and then provide temporary postoperative support using the TandemHeart.

The patient was taken to the operating room and positioned for a right thoracotomy. The left femoral artery and vein were exposed and cannulated for cardiopulmonary bypass (CPB). The transseptal left atrial cannula of the TandemHeart was also inserted into the left femoral vein, 2 cm distal to the insertion site of the venous cannula for CPB. The 2 cannulae were positioned side-by-side and were inserted up the inferior vena cava to the atrial–caval junction. A right thoracotomy was then performed, and the heart was exposed. A 2nd venous cannula was placed in the superior vena cava to enable right atrial isolation, and superior and inferior caval tapes were placed. Cardiopulmonary bypass was initiated, the patient was cooled to 28 °C, and the caval tapes were snared. After performing a standard right atriotomy, we used a transseptal approach for mitral valve exposure.

Both valves were found to be largely destroyed by what appeared to be old endocarditis, and were replaced under hypothermic fibrillatory arrest. Bioprostheses were used, because we felt that advanced cirrhosis would complicate long-term anticoagulation. After completion of valve replacement, the inferior vena caval tape was momentarily released to allow the pVAD's inflow cannula to be advanced into the surgical field. A separate 6-mm incision was made in the atrial septum at the area of the fossa ovalis, through which the end of the inflow cannula was passed into the left atrium. The larger transseptal incision, through which the mitral valve was replaced, was then closed in a hemostatic fashion. A cardiotomy sucker was connected to the transseptal inflow cannula to assist in de-airing the left side of the heart. The right atriotomy incision was closed, the tapes were removed, and the patient was weaned from CPB with inotropic support. We immediately connected the pVAD to both the transseptal atrial inflow cannula and the arterial cannula that was used for CPB. The pVAD flows were gradually increased to approximately 3 L/min to maintain a continuous mixed venous oxygen saturation of more than 65%. The right thoracotomy was closed, and the patient was taken to the intensive care unit.

On postoperative day 4, the patient's ventricular function had improved sufficiently that she could be weaned from the TandemHeart, and the device was removed through the same small groin incision used for CPB. Transesophageal echocardiography was used to evaluate cardiac function and to guide cannula removal. In addition, the atrial septal defect was evaluated and showed no shunting. Three months later, the patient continued to do well.

Discussion

To our knowledge, this report describes the 1st documented use of a pVAD as an elective support device for a patient undergoing high-risk mitral or tricuspid surgery. We believe that the pVAD provided crucial postoperative left ventricular support for our patient with biventricular failure.

Postcardiotomy mechanical circulatory support has historically been used as a life-saving effort for patients who could not be weaned from CPB despite the administration of high-dose inotropic agents. These devices usually require a subsequent open-chest procedure for removal. However, recent refinement of the technology for percutaneous insertion and removal of temporary ventricular assist devices has facilitated and expanded their use. Kar and colleagues¹ reported their clinical experience with the TandemHeart pVAD in 18 patients, 11 of whom were in cardiogenic shock; 11 of the 18 patients (61%) survived for 30 days or longer. Pitsis and associates³ documented their use of a pVAD in 2 patients who could not be weaned from CPB despite placement of an intra-aortic balloon pump (IABP).

The IABP is often placed electively in high-risk surgical patients.⁴ Its simplicity and ease of insertion make it convenient to use, and it remains an important tool. However, the amount of support that the IABP can provide may be insufficient for patients who have biventricular failure or severely depressed left ventricular function.¹ In contrast, the pVAD can provide flows up to 4 L/min and has been shown to support an acutely failing ventricle more effectively than does the IABP.⁵

Insertion of the TandemHeart is safe and easy. In the patient described here, safety was increased by intraoperative insertion of the inflow cannula under direct vision and echocardiographic guidance. Furthermore, the device's removal, in contrast with other ventricular assist devices, does not require a 2nd sternotomy. Our experience with this patient illustrates the planned, pre-emptive surgical use of an effective, minimally invasive technology that might be used to treat patients for whom the operative risk would otherwise be prohibitive.