Suzanne Harton

Exercise blood pressure response during assisted circulatory support: Comparison of the total artifical heart with a left ventricular assist device during rehabilitation

BACKGROUND The total artificial heart (TAH) consists of two implantable pneumatic pumps that replace the heart and operate at a fixed ejection rate and ejection pressure. We evaluated the blood pressure (BP) response to exercise and exercise performance in patients with a TAH compared to those with a with a continuous-flow left ventricular assist device (LVAD). METHODS We conducted a single-center, retrospective study of 37 patients who received a TAH and 12 patients implanted with an LVAD. We measured the BP response during exercise, exercise duration and change in tolerated exercise workload over an 8-week period. RESULTS In patients with a TAH, baseline BP was 120/69 ± 13/13, exercise BP was 118/72 ± 15/10 and post-exercise BP was 120/72 ± 14/12. Mean arterial BP did not change with exercise in patients with a TAH (88 ± 10 vs 88 ± 11; p = 0.8), but increased in those with an LVAD (87 ± 8 vs 95 ± 13; p < 0.001). Although the mean arterial BP (MAP) was negatively correlated with metabolic equivalents (METs) achieved during exercise, the association was not statistically significant (β = -0.1, p = 0.4). MAP correlated positively with METs achieved in patients with LVADs (MAP: β = 0.26, p = 0.04). Despite the abnormal response to exercise, patients with a TAH participated in physical therapy (median: 5 days; interquartile range [IQR] 4 to 7 days) and treadmill exercise (19 days; IQR: 13 to 35 days) early after device implantation, with increased exercise intensity and duration over time. CONCLUSIONS During circulatory support with a TAH, the BP response to exercise was blunted. However, aerobic exercise training early after device implantation was found to be safe and feasible in a supervised setting.

Implantable Mechanical Circulatory Support: Demystifying Patients With Ventricular Assist Devices and Artificial Hearts

Engineering advancements have expanded the role for mechanical circulatory support devices in the patient with heart failure. More patients with mechanical circulatory support are being discharged from the implanting institution and will be seen by clinicians outside the immediate surgical or heart‐failure team. This review provides a practical understanding of device design and physiology, general troubleshooting, and limitations and complications for implantable left ventricular assist devices (pulsatile‐flow and continuous‐flow pumps) and the total artificial heart.

Fracture of the total artificial heart pneumatic driveline after transition to the portable driver

The CardioWest (SynCardia Systems Inc, Tucson, AZ) total artificial heart (TAH) consists of polyurethane ventricles with pneumatically driven diaphragms and 4 mechanical tilting disk valves that replace the entire heart. A polyvinyl chloride wire–reinforced pneumatic conduit (permanent driveline) attaches to each pump. The drivelines are tunneled through the left rectus muscle to the left upper quadrant and are covered with velour to promote tissue ingrowth. The permanent drivelines are attached via connecters to longer tubing that attaches to the pneumatic driver and is replaceable. Although rehabilitation and mobility are feasible with the TAH, implantation of the device until recently required patients to remain tethered to a 418-pound inpatient driver until a heart transplant donor became available. With the introduction the TAH portable Freedom Driver (SynCardia Systems), which has not yet been approved by the Food and Drug Administration, patients may look forward to increased mobility and potential discharge from the hospital. Although improving patient quality of life, increased patient mobility could increase stress and torque