Surgical placement of a wireless telemetry device for cardiovascular studies of bovine calves

Background: Domestic cattle ( Bos taurus) are naturally susceptible to hypoxia-induced pulmonary arterial hypertension; consequently, the bovine calf has been used with considerable success as an animal model of the analogous human condition. Studies to date, however, have relied on instantaneous measurements of pressure and cardiac output. Here, we describe the surgical technique for placement of a fully implantable wireless biotelemetry device in a bovine calf for measurement of pulmonary arterial and left ventricular pressures, right ventricular output, and electrocardiogram. Methods: Three, 2-month old bovine calves underwent left-sided thoracotomies. A transit-time flow probe was placed around the pulmonary artery and solid-state pressure catheters inserted into the pulmonary artery and left ventricle. Biopotential leads were secured to the epicardium. The implant body was secured subcutaneously, dorso-caudal to the incision. Results: The implant and sensors were successfully placed in two of the three calves. One calf died from ventricular fibrillation following left ventricular puncture prior to pressure sensor insertion. Anatomical discrepancies meant that either 4 ^th or 5 ^th rib was removed. The calves recovered quickly with minimal complications that included moderate dyspnea and subcutaneous edema. Conclusions: Left thoracotomy is a viable surgical approach for wireless biotelemetry studies of bovine calf cardiovascular function. The real-time, contemporaneous collection of cardiovascular pressures and output, permits pathophysiological studies in a naturally susceptible, large animal model of pulmonary arterial hypertension.