Search

The temporary total artificial heart (TAH-t) has emerged as an effective bridge to transplantation for individuals with biventricular failure. Implantation of a TAH-t creates a hypercoagulable state requiring a multidrug approach that includes low-dose unfractionated heparin (UFH) in order to minimize thromboembolism. A concern with UFH is the development of heparindependent antibodies, which develop in up to 50% of patients receiving the drug as part of cardiopulmonary bypass. If UFH therapy continues postoperatively, the risk of heparin-induced thrombocytopenia approaches 3%. Small investigations have demonstrated that bivalirudin, given as a bolus of 0.75-1 mg/kg followed by an infusion at 1.75-2.5 mg/kg/hour, is an effective alternative to UFH for therapeutic anticoagulation during coronary artery bypass surgery, valve replacement, or both. We describe a series of five adults (age range 24-58 yrs) who received bivalirudin as an alternative to low-dose UFH after TAH-t implantation. None of the patients had documented heparin-induced thrombocytopenia. Treatment was started at the discretion of the treating physician, and adjustments were based principally on the results of thromboelastography. Additional general monitoring included activated partial thromboplastin time, prothrombin time, international normalized ratio, fibrinogen, D-dimer, platelet count, hemoglobin, hematocrit, and platelet aggregation studies. Bivalirudin therapy was continued until successful warfarin implementation. All five patients received bivalirudin in addition to standard antithrombotic therapy. Bivalirudin treatment started at a dosage of 0.005 or 0.01 mg/kg/hour with titration to maintain normocoagulability, which occurred (without concomitant warfarin therapy) within the dosage range of 0.01-0.02 mg/kg/hour. Duration of TAH-t implantation was a mean of 38.8 days (range 25-60 days), and bivalirudin was continued for a mean of 15.2 days (range 7-24 days). No major hemorrhagic events occurred during treatment, and all patients successfully transitioned to warfarin therapy. Low-dose bivalirudin, as an alternative to UFH, maintained normocoagulability after TAH-t implantation. Further investigation is warranted to define the role and dosing of bivalirudin in this situation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The CardioWest™ temporary total artificial heart serves as a viable bridge to orthotopic heart transplantation in patients who are experiencing end-stage refractory biventricular heart failure. This device is associated with a low, albeit still substantial, risk of thrombosis. Platelet interactions with artificial surfaces are complex and result in continuous activation of contact proteins despite therapeutic anticoagulation. We searched the medical literature publication dates, January 1962--October 2009) in order to evaluate means of mitigating adverse events that have occurred after implantation of the CardioWest temporary total artificial heart. We conclude that the use of a multitargeted antithrombotic approach, involving anticoagulation (bivalirudin and warfarin) and antiplatelet therapy (dipyridamole and aspirin), can mitigate the procoagulative effects of mechanical circulatory assist devices, particularly those that are associated with the CardioWest temporary total artificial heart. Careful monitoring with use of a variant multisystem approach, involving efficacy tests (thrombelastography and light transmittance aggregometry), safety tests (laboratory analyses), and warfarin genomics, may maximize the therapeutic actions and minimize the bleeding risks that are associated with the multitargeted antithrombotic approach. The development and monitoring of individualized antithrombotic regimens require that informed health professionals appreciate the complexities and grasp the hazards that are associated with these therapies. [ABSTRACT FROM AUTHOR]