Biventricular mechanical assist for complex, acute post-infarction ventricular septal defect

Overview of Mechanical Circulatory Support for the Management of Post-Myocardial Infarction Ventricular Septal Rupture

Post-myocardial infarction ventricular septal rupture (PIVSR) is becoming increasingly rare in the percutaneous coronary intervention era; however, the mortality rates remain high. Surgical repair is the gold standard treatment for PIVSR but is associated with surgical difficulty and high mortality. Therefore, the timing of surgery is controversial (i.e. either undertake emergency surgery or wait for resolution of organ failure and scarring of the infarcted area). Although long-term medical management is usually ineffective, several mechanical circulatory support (MCS) devices have been used to postpone surgery to an optimal timing. Recently, in addition to venous arterial extracorporeal membrane oxygenation (VA-ECMO), new MCS devices, such as Impella (Abiomed Inc., Boston, MA, USA), have been developed. Impella is a pump catheter that pumps blood directly from the left ventricle, in a progressive fashion, into the ascending aorta. VA-ECMO is a temporary MCS system that provides complete and rapid cardiopulmonary support, with concurrent hemodynamic support and gas exchange. When left and right heart failure and/or respiratory failure occur in cardiogenic shock or PIVSR after acute myocardial infarction, ECpella (Impella and VA-ECMO) is often introduced, as it can provide circulatory and respiratory assistance in a shorter period. This review outlines the basic concepts of MCS in PIVSR treatment strategies and its role as a bridge device, and discusses the efficacy and complications of ECpella therapy and the timing of surgery.

Hemodynamic Effects of Mechanical Circulatory Support Devices in Ventricular Septal Defect

Background:

Ventricular septal defect (VSD) is a lethal complication of acute myocardial infarction (AMI) and is often associated with cardiogenic shock. The optimal form of percutaneous mechanical circulatory support (MCS) for AMI-VSD is unknown.

Methods and Results:

We used a previously validated cardiovascular model to simulate AMI-VSD with parameters adjusted to replicate average hemodynamics reported in the literature, including a pulmonary-to-systemic blood flow ratio of 3.0. We then predicted effects of different types of percutaneous MCS (including intra-aortic balloon pumping, Impella, TandemHeart, and extracorporeal membrane oxygenation) on pressures and flows throughout the cardiovascular system. The simulation replicated all major hemodynamic parameters reported in the literature with AMI-VSD. Inotropes and vasopressors worsened left-to-right shunting, whereas vasodilators decreased shunting at the expense of worsening hypotension. All MCS devices increased forward blood flow and arterial pressure but other effects varied among devices. Impella 5.0 provided the greatest degree of pulmonary capillary wedge pressure reductions and decreased left-to-right shunting. Extracorporeal membrane oxygenation worsened pulmonary capillary wedge pressure and shunting, which could be improved by adding Impella or passive left ventricular vent. Pulmonary-to-systemic blood flow ratio could not be reduced below 2.0, and pulmonary flows remained high with all forms of MCS.

Conclusions:

Although no form of percutaneous MCS normalized hemodynamics in AMI-VSD, pulmonary capillary wedge pressure and shunting were worsened by extracorporeal membrane oxygenation and improved by Impella. Accordingly, based on hemodynamics alone, Impella provides the optimal form of support in AMI-VSD. However, other factors, including team experience, device availability, potential for tissue ingestion, and clinical characteristics, need to be considered when choosing a percutaneous MCS device for AMI-VSD.

Perioperative use of TandemHeart percutaneous ventricular assist device in surgical repair of postinfarction ventricular septal defect

Mortality for patients presenting with acute myocardial infarction (AMI) complicated by ventricular septal defect (VSD) and cardiogenic shock is very high even with surgical repair. We report our experience regarding utilization of TandemHeart, a percutaneous ventricular assist device (pVAD) as an adjunct to the treatment of these patients. Retrospective case series study design included a total of 11 patients with post-AMI VSD and severe refractory cardiogenic shock who received pVAD support at our institution. Three patients underwent immediate surgical repair and received pVAD support for postcardiotomy cardiogenic shock for 2, 4, and 7 days, respectively. However, all three died. The other eight patients had pVAD implanted prior to surgical repair in order to rest the myocardium before operation. Hemodynamics improved immediately after pVAD placement, and after receiving pVAD support for 7 ± 3 days, they underwent surgical VSD repair. Their total pre- and post-surgical pVAD support was 14 ± 4 days. All eight survived 30 days postoperatively. At 6 months postsurgery overall survival rate was 75%. Our small series of these critically ill patients shows a trend toward better survival after immediate pVAD placement to stabilize the patient and allow for myocardial maturation before surgical VSD repair.