Surgical Implantation of A Cardiac Resynchronization Therapy Device in A Western Lowland Gorilla (Gorilla gorilla gorilla) with Fibrosing Cardiomyopathy

Abstract

A 24-yr-old, male western lowland gorilla (Gorilla gorilla gorilla) was diagnosed in March of 2003 with congestive heart failure (CHF). Transesophageal and transthoracic echocardiography demonstrated global left and right ventricular hypokinesia with a left ventricular ejection fraction of 0.20. At the time of diagnosis, the animal exhibited symptoms and signs of CHF with minimal exertion (New York Heart Association class III). Over a 16-mo period, the severity of CHF progressed to class IV (resting signs and symptoms) despite angiotensin-converting enzyme inhibition, beta-blockers, and diuretics. Because of intractable CHF and a QRS duration that was markedly prolonged compared with the normal range for this species, a cardiac resynchronization therapy (CRT) device was implanted using implantation techniques based on human surgical procedures. Placement of the right ventricular, right atrial, and left ventricular leads and pulse generator were accomplished in 5.5 hr. Telemetry of the device postoperatively via wand or remote radio frequency has allowed for noninvasive programming and interrogation. The clinical improvement in CHF with this therapy was immediate and dramatic for this animal. Six months after CRT device implantation, the device leads became dislodged during an altercation with another gorilla, with the rapid development of CHF upon cessation of biventricular pacing. A second procedure to replace the leads returned the gorilla to his previous level of activity. In 2007, the pulse generator was electively replaced for battery depletion with a device capable of remote radiofrequency programming and interrogation. CRT implantation, although requiring specialized equipment and surgical skill, appears to be a viable option for treatment of dilated cardiomyopathy in gorillas.