Cardiac Pacemaker Implantation for Management of Atrioventricular Block in Two Tasmanian Devils (Sarcophilus harrisii)
Atrioventricular block (both second degree and third degree) has been documented in aged Tasmanian devils (Sarcophilus harrisii), with onset of disease typically at >5 years of age.1 Recommended therapy consists of surgical implantation of a pacemaker to bypass abnormal conduction fibers and allow for appropriate ventricular contraction. Despite being considered a simple surgical procedure in many species, pacemaker implantation has not been performed in a Tasmanian devil. Two male Tasmanian devils, ages 3.5 and 6 years, were diagnosed with atrioventricular block after acute onset of intermittent collapse and during a routine health examination, respectively. Electrocardiography revealed atrioventricular block in both cases. Radiography and echocardiography confirmed the absence of congestive heart failure. A unipolar ventricular cardiac pacemaker was placed via a trans-diaphragmatic approach, with the generator placed in a pocket created in the transversus abdominis muscle. Both animals recovered from surgery and have had no postoperative complications. Two recheck exams each have confirmed successful alleviation of clinical signs of conduction deficits with no loss of cardiac muscle contractility. Although not validated in Tasmanian devils, troponin I was measured to evaluate for myocardial damage. Compared to troponin I levels in three unaffected devils, troponin I levels in the devils with atrioventricular block were 10- to 37-fold higher at the time of pacemaker implantation. Troponin I levels then declined after pacemaker placement, though at different rates. These two cases illustrate that cardiac pacemakers can be placed in Tasmanian devils, resulting in improved cardiac function and quality of life for affected animals.
The authors would like to thank Dr. Kim Rainwater and Dr. Michael Barrie for their involvement at the Toledo Zoo & Aquarium.
1. Zoo and Aquarium Association, Tasmanian Department of Primary Industries, Parks, Water, and Environment. Management guidelines for aged Tasmanian devils. Save the Tasmanian Devil Program; 2013.