Dual Arterial Cannulation for Aortic Surgical Procedures in Adult Sheep

Abstract

Background/Aims: Preclinical site-specific placement of valvular prostheses is highly recommended to fully appreciate hemodynamics. An ovine model is commonly used for preclinical prosthetic mitral valve evaluation; however, the ideal animal model for prosthetic aortic valve evaluation has yet to be determined. Past studies have utilized adult sheep for prosthetic aortic valve replacement; however, an anatomically short length of the ascending aorta can present a surgical challenge during implantation. Due to this anatomically short length of the ascending aorta, we designed an arterial cannulation technique for cardiopulmonary bypass (CPB) to provide a more ideal operative setting. Methods: Dual arterial cannulation for CPB was used in adult Polypay sheep (n = 15) subjected to an aortic root/valve surgical procedure. Results: The arterial cannulation technique described in this paper was successful in performing aortic root/valve surgical procedures in adult sheep. All animals survived the operative procedure without complications. Postoperatively, all animals were alert, neurologically intact and assumed normal daily functions following extubation, which continued throughout their survival. Conclusions: The use of this arterial cannulation technique was safe, provided better visualization of the aortic root/valve area, less difficulty in performing the aortic root/valve surgical procedure, and less observed tissue tension while closing the aortotomy.

Chronic aortic root pressure-loading assessment model

“…Electrocardiographic leads were placed. Both esophageal and rectal temperature probes were placed for continuous monitoring of core temperature [Kopcak et al 2010].…”

“…Both arterial cannulas were connected in a "Y" fashion. A single-stage venous cannula (34-36 Fr, Medtronic-DLP Inc., Grand Rapids, MI) was placed into the right atrium at the previously placed pursestring suture for venous drainage [Kopcak et al 2010].…”

“…The animal was placed on CPB and cooled to 32°C. A 14 Fr ventricular venting catheter (Medtronic-DLP, Inc.) was inserted into the left ventricle at the previously placed mattress suture [Kopcak et al 2010].…”

“…When the cross clamps were applied, cold (4°C) blood cardioplegia (4:1 ratio; crystalloid with 20 mEq potassium; Plegisol, Hospira, Inc., Lake Forest, IL) was instilled into the ascending aorta through the previously placed cardioplegic cannula. Additional dosages of cold blood cardioplegia were instilled at approximately 15-20 minute intervals or when electrical activity was observed [Kopcak et al 2010].…”

“…When hemodynamically stable, the animal was weaned from CPB and decannulated. A left pleural chest tube was placed and the thoracotomy and neck inci-sion were closed in routine fashion [Kopcak et al 2010]. The wires from the pressure-load sensing device exited through the chest wall and were connected to the device's power source, which resided in a created subcutaneous pocket.…”