Twenty‐four hour continuous transvenous temporary right ventricular pacing in healthy horses

Abstract

Abstract Background The ability to perform transvenous temporary cardiac pacing (TV‐TP) is critical to stabilize horses with symptomatic bradyarrhythmias. Reports of successful TV‐TP in horses are limited, and only briefly describe short‐term pacing. Objective To describe temporary, medium‐term (24 h) transvenous right ventricular pacing in awake horses using a bipolar torque‐directed pacing catheter. Animals Six healthy adult institutional teaching horses. Methods Prospective experimental study with 2 immediately successive TV‐TP lead placements in each horse with a target location of the RV apex. One placement was performed primarily with echocardiographic guidance and 1 primarily with fluoroscopic guidance. In all placements, corresponding images were obtained with both imaging modalities. Horses were then paced for 24 h, unrestricted in a stall with continuous telemetric ECG monitoring. Echocardiographically determined lead position, episodes of pacing failure in the preceding 6 h, and pacing thresholds were recorded every 6 h. Pacing failure was defined as a period of loss of capture longer than 20 s. Results Pacing leads were placed with both guidance methods and maintained for 24 h with no complications. Two horses with leads angled caudally in the right ventricular apex had no pacing failure, the remaining 4 horses had varying degrees of loss of capture. Leads located in the right ventricular apex had longer time to pacing failure and lower capture thresholds P < 0.05. Conclusions and Clinical Importance Medium‐term TV‐TP is feasible and has potential for stabilization of horses with symptomatic bradyarrhythmias. Lead position in the right ventricular apex appears optimal. Continuous ECG monitoring is recommended to detect pacing failure.

Keywords

• atrioventricular block
• cardiac
• echocardiography
• equine
• syncope fluoroscopy