The AbioCorTM was implanted in a 6-month old male calf. The internal components of the AbioCorTM consist of the thoracic unit, the electronic controller with a radio frequency communication, a rechargeable battery, and the secondary coil of a transcutaneous energy transmission device (TET). The primary coil of the TET was placed externally over the secondary coil. A computer console was used to display physiologic pressures as well as telemetric data from the implanted controller. Physiologic parameters monitored included AoP, LAP, PAP, and CVP. Device parameters recorded included beat rate, hydraulic pressures, voltage, current, power, and internal temperatures of the implanted components. Over the 12-week implant period the CO was maintained around 9 L/min, near the systems maximum output. The mean AoP, LAP, and SVC were 100±13 mmHg, 19±5 mmHg, and 18±5 mmHg respectively. The animal underwent five instrumented treadmill studies. PvO2 reduction was observed due to increased metabolic demand. Throughout the study hemoglobin and hematocrit were 9.9±1.6 mg/dL and 29.6±5.2% respectively. The plasma free hemoglobin was 3.1±1.9 mg/dL and was within normal limits. Antibiotic therapy was given during the last three weeks due to positive blood cultures secondary to indwelling monitoring catheters. Otherwise, infection was not a complicating factor. Pathology demonstrated no gross evidence of thromboembolic events. Liver congestion was evident due to increasing growth-driven cardiac need of the animal exceeding the maximum device output. Although long term (12-week) study duration is feasible with a fully implantable total heart, a device capacity designed for human use will lead to flow-limited pathology in growing calves. Shorter study duration is advisable for replacement heart device evaluation in the bovine model.

Infection is a problem in patients undergoing support with left ventricular assist systems. To better understand the nature of this problem, we retrospectively analyzed data on 56 patients supported by the HeartMate (Thermo Cardiosystems, Inc, Woburn, MA) left ventricular assist system. Infection was defined as fever > 38 degrees C, white blood count > 12,000 cells/ml, and a need for antimicrobial therapy. Of the 56 patients, 25 (41%) had an infection. Device related infections (as determined by positive culture from driveline, housing, or inflow or outflow tract) occurred in eight patients (14.3%). The most common sites of infection were the respiratory system (42.4%), the central venous catheter (27.8%), and blood (18.3%). Of the positive cultures, 84% were bacterial and 16% fungal. There were no positive viral cultures. Positive cultures from left ventricular assist system related sites made up only 8.7% of the total. All but one of the patients with device related infections survived to transplantation. The long-term survival rate for patients in this group after transplantation was 77.8%. Two patients required surgical revision of the driveline because of infection. Both were free of infection postoperatively. Patients who stayed in the intensive care unit for longer periods had a greater risk of infection (uninfected, 35 days; infected, 78 days). In conclusion, although infection is a problem in patients undergoing support with left ventricular assist systems, it does not preclude survival to transplantation or alter the survival rate after transplantation.

The HeartMate left ventricular assist system (LVAS) is being used with increasing frequency as a bridge to heart transplantation and for long-term support of chronic heart failure patients who are not transplant candidates. The surgical techniques and anatomic placement of the HeartMate are factors in minimizing complications that occur during long-term use. Device related bleeding, infection, and other intraabdominal complications are serious adverse events associated with the position of the LVAS. Clinical data from 48 HeartMate supported patients were analyzed retrospectively to determine differences in serious complication rates between intraperitoneal (IP) and extraperitoneal (EP) LVAS placement. The LVAS was placed IP in 37 patients (77%) and EP in 11 patients (23%). The occurrence of postoperative bleeding that required reoperation was 57% in the IP group and 64% in the EP group. Device related bleeding was 8% in the IP group and 29% in the EP. Neither difference in bleeding rate was statistically significant. The overall infection rate during the entire period of LVAS support was similar between groups (IP, 45.7%; EP, 46.2%; p = 0.25); however, device related infection occurred more often in the EP group (46%; IP, 14%; p = 0.025). All patients who recovered from LVAS implantation experienced mild early satiety, but were otherwise free of intra-abdominal complications. The transplantation rate was 64% for the IP group and 78% for the EP group. IP LVAS placement may offer additional protection against device related infections.