The LionHeart LVD-2000: a completely implanted left ventricular assist device for chronic circulatory support

Estimation of coupled assist flows in a moving-actuator bi-ventricular assist device using interventricular pressure

An assist flow estimation scheme for a moving-actuator biventricular assist device (MA-BVAD) using interventricular pressure (IVP) has been developed. The scheme uses a waveform feature parameter of IVP, peak IVP time (PIT), for estimation of the filling volumes of both left and right blood sacs simultaneously. In a regression analysis on data from an in vivo test in an 85 Kg male calf for 20 days, the PIT was found to have high correlation with the blood sac filling volume (R=0.883: left filling volume, R=0.967: right filling volume). A conceptual equation hypothesizing this correlation between PIT and filling volume was established based on the observation and the unknown parameters were identified using least squares parameter optimization. The estimation equation identified proved highly accurate (R=0.916 for left flow, R=0.970 for right flow). The accuracy of the estimation scheme promises very good practical applicability.

Preliminary experience with the LionHeart left ventricular assist device in patients with end-stage heart failure

BACKGROUND

The Arrow LionHeart LVD 2000 left ventricular assist device is the first fully implantable system designed for destination therapy. We report on 2 years of experience with this device, which we implanted for the first time in October 1999.

METHODS

Since October 1999, 6 male patients between 55 and 69 years of age (mean 65 +/- 6 years) have received the device at our center; all were in New York Heart Association functional class IV and ineligible for heart transplantation.

RESULTS

All surgical procedures were uneventful, with a timely extubation in 5 of 6 patients. Duration of support was 17 to 670 (mean 245 +/- 138) days, with a cumulative experience of 4.5 years. Three patients recovered to be discharged from hospital under support and are long-term survivors. Three patients died 17, 31, and 112 days after implantation from multiple organ failure without being discharged to their homes. The survival rate is 50% after 18 months. There were no major system-related problems or any device-related infections, which are otherwise commonly found among vertricular assist device patients.

CONCLUSIONS

Our preliminary experience demonstrates the reliability and efficacy of the different parts of the system. Nevertheless, further sophistication is needed to reduce the size of its components, which so far still constitutes a limiting factor.

Long-term implantable left ventricular assist devices: out-of-hospital program

The assist devices demonstrate the safety and reliability of these systems in the management of end-stage cardiac failure, not only in an in-hospital setting, but also in the cohort of OOH patients. The OOH option has led to a significant improvement in the quality of life of those patients. However, VADs are still associated with a considerable number of complications. The newly introduced fully implantable system (LionHeart) has reduced significantly the system-related infection complications. Further miniaturization of the systems might reduce the comorbidities and increase the acceptance of this therapeutic option in the management of end-stage cardiac failure.

Devices as destination therapy

The use of circulatory support as destination therapy has been a goal for the treatment of endstage heart failure for several decades. Current investigations are evaluating several circulatory pumps with that particular objective. With continued modification of design, the current and future pumps will become more reliable and provide improved quality of life to patients in need of mechanical circulatory assistance. The new pumps on the horizon specifically address reliability, size, and cost, and are based on the centrifugal system. These devices use the Maglev (Magnetic Levitation) concept that allows for frictionless pumping, low thrombogenicity, minimal noise, and increased durability. Further research with this goal in mind and support from the federal government will be the key to the future use of circulatory assistance as destination therapy for heart failure patients. In addition, the cost-effectiveness of these devices will need to be maintained as the technology improves, as in any new technology that confronts a more intuitive option like the native heart.

Mechanical circulatory support: new advances, new pumps, new ideas

Mechanical circulatory support (MCS) is a viable therapy for severe end-stage heart disease. Most obstacles to long-term MCS therapy have been overcome, and a number of clinical trials, including the recent REMATCH trial, have shown a clear benefit in terms of survival and improved quality of life. MCS should therefore no longer be considered as simply a temporary bridge to other therapies, but also a destination therapy whose potential should continue to expand through the development and use of newer, more innovative devices such as continuous flow pumps, next-generation centrifugal pumps, and total artificial hearts. The homebound heart failure patient and the patient facing imminent death from massive myocardial infarction receive little statistical benefit from current therapies, and the new and evolving MCS technologies offer the potential for effective therapy to these desperately ill patients.