Direct mechanical assistance of the right ventricle with the Hemopump in a porcine model

The Evolution of Durable, Implantable Axial-Flow Rotary Blood Pumps

Left ventricular assist devices (LVADs) are increasingly used to treat patients with end-stage heart failure. Implantable LVADs were initially developed in the 1960s and 1970s. Because of technological constraints, early LVADs had limited durability (eg, membrane or valve failure) and poor biocompatibility (eg, driveline infections and high rates of hemolysis caused by high shear rates). As the technology has improved over the past 50 years, contemporary rotary LVADs have become smaller, more durable, and less likely to result in infection. A better understanding of hemodynamics and end-organ perfusion also has driven research into the enhanced functionality of rotary LVADs. This paper reviews from a historical perspective some of the most influential axial-flow rotary blood pumps to date, from benchtop conception to clinical implementation. The history of mechanical circulatory support devices includes improvements related to the mechanical, anatomical, and physiologic aspects of these devices. In addition, areas for further improvement are discussed, as are important future directions-such as the development of miniature and partial-support LVADs, which are less invasive because of their compact size. The ongoing development and optimization of these pumps may increase long-term LVAD use and promote early intervention in the treatment of patients with heart failure.

Temporary Right Ventricular Support with Impella Recover RD Axial Flow Pump

Post-cardiotomyright ventricular failure is a serious complication that frequently results in adverse outcomes. We reviewed our experience with the Impella Recover RD (Impella Cardiosystems GMbH, Aachen, Germany). From January 2007 to December 2007, 7 patients (5 males, 54 + 7 years old) had this device implanted for temporary support after heart transplantation in 4, after repeat mitral valve replacement in 2, and with a left ventricular assist device in 1. Devices were implanted during initial operation ( n = 5) or shortly thereafter ( n = 2). Six patients underwent implantation without cardiopulmonary bypass. Effective support with pump flows of 4.0-4.5 L · min−1 and adequate unloading (central venous pressure decreased from 15.3 ± 1.4 to 9.4 ± 1.2 mm Hg) was achieved in all patients. Patients were assisted for a mean duration of 4.9 ± 4.5 days. Three patients could be weaned after 7.0 ± 5.6 days of support and underwent device explantation without cardiopulmonary bypass. One of these patients died of recurrent right ventricular failure, 2 remained stable but died later of sepsis. The patient with a left ventricular assist device was switched to an alternative device for prolonged support. Two patients experienced pump dysfunction. Our preliminary experience shows that the Impella Recover RD is an effective device that can be easily implanted and explanted. However, its mechanical reliability needs to be improved.

Copulsation balloon for right ventricular assistance: preliminary trials

BACKGROUND

Options for management of acute right ventricular (RV) failure are limited. This report describes preliminary testing of a temporary RV assist device that acts by direct compression of the RV. The system comprises a pancake-shaped silicone balloon (5 cm diameter) connected to a drive console that delivers a 65-mL pneumatic pulse during cardiac systole.

METHODS AND RESULTS

Initial in vivo tests were performed on 6 pigs (weight, 41+/-4 kg). RV wall motion and stroke volume were monitored via transesophageal echocardiography. Acute RV failure was created by graded right coronary ligation, which yielded a 63% reduction in RV stroke volume (39.9+/-8.2 to 14.7+/-1.9 mL; P<0.002). We secured the balloon over the RV free wall by attaching it to the edges of the opened pericardium. The sternum was then reapproximated, and data were collected with the device off and on (every beat). Device placement had no deleterious effect on RV function. Balloon activation returned RV stroke volumes to normal (37.8+/-9.2 mL) and increased mean pulmonary artery pressures from 13+/-2 to 16+/-3 mm Hg (P<0.01). RV compression did not induce or exacerbate tricuspid regurgitation. Mean aortic pressure improved from postinfarction levels but did not return to normal.

CONCLUSIONS

We conclude that the pulmonary circulation can be supported in the short term via cardiac compression and that balloon copulsation techniques for short-term RV failure should be tested in long-term models.