A safe and simple method of preserving right ventricular function during implantation of a left ventricular assist device

Aorto-pulmonary bypass shunt for intraoperative right ventricular support during LVAD implantation

We describe a simple modification of the cardiopulmonary bypass (CPB) circuit that allows selective intraoperative circulatory support of the right ventricle during left ventricular assist device (LVAD) implantation. The addition of a side branch to the arterial line and an intermediate line connector allows selective venting and perfusion through a cannula inserted in the main pulmonary artery. This modification of the CPB circuit allows for selective evaluation of right ventricular function, titration of inotropic support, and early identification of patients that require right ventricular assist device (RVAD) support.

Ventricular assist devices in children: current achievements and future perspectives

Mechanical circulatory support systems for the treatment of acute and chronic heart failure are now available for use in several clinical situations and are designed for different indications and support times. In children, particularly in small infants, extracorporeal membrane oxygenation and centrifugal pumps have been most widely used in the past. These systems are preferred for support after cardiac operations and for use in patients who have concomitant respiratory failure, but they are suitable for short-term application only and intensive care is obligatory. VADs are designed for long-term application and allow patients to be discharged home. Pneumatic pulsatile VADs have been available in pediatric sizes since 1992. Currently at our institution, 74 children have been supported with pediatric extracorporeal VADs for up to 14 months. In the past five yr, a notable rise in survival has been achieved by improvements in pump design and pre- and post-operative management. We have been able to discharge 78% of the infants under one yr old. In this review, our current VAD experience in children will be presented in the light of improvements in decision-making, device technology, and implantation techniques, and in coagulation monitoring and anticoagulation. Additionally, new developments in the field of pediatric assist devices will be presented.

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.

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.

Ventricular assist devices

PURPOSE OF REVIEW

Recent advances in technology as well as new indications for implantation have appeared in the field of ventricular assist devices. Progress has also been made in the understanding of the underlying mechanisms of myocardial recovery after ventricular assist device support.

RECENT FINDINGS

Technological progress includes the development of fully implantable pulsatile and continuous flow pumps, either axial flow or centrifugal, for left ventricular and total heart assistance. Among the new indications for ventricular assist device support, the most important is the use of the device as permanent treatment for end-stage cardiac failure patients. Increased knowledge has been acquired regarding the effects of mechanical assistance and of unloading of the heart on haemodynamics, as well as on the cellular, molecular and electrophysiological characteristics of the failing heart. All these findings suggest that depressed myocardial function can sometimes recover with ventricular assist device therapy. Ventricular assist device support, however, still carries a high rate of complications: the device itself can fail, bleeding and thromboembolism are common, immunity is disturbed and the incidence of infection remains high.

SUMMARY

In patients with end-stage heart failure, ventricular assist devices can be used as a bridge to transplantation or to recovery, but they are now also considered as a long-term myocardial replacement therapy. Which device is the most appropriate for each indication, however, remains to be defined. Even if the underlying mechanisms of myocardial recovery are progressively clarified, the use of ventricular assist devices as a bridge to recovery still has limited clinical success. Clinical trials with the fully implantable devices are in their early stages, but these pumps appear promising in terms of efficacy, reliability and complication rate, as well as being easy to implant. Because more patients will benefit from ventricular assist device placement in the future, anaesthesiologists must be prepared to manage patients undergoing ventricular assist device placement or presenting for noncardiac surgery while under ventricular assist device support.