Echocardiographic assessment of aortic valve annular and left ventricular outflow tract diameter in conscious and anesthetized adult sheep prior to prosthetic aortic valve implantation.

OBJECTIVE: Prosthetic heart valve implantation is commonly performed in patients that have valvular heart disease. Prior to clinical evaluation of newly developed prostheses, preclinical animal studies are performed for the assessment of both acute and chronic valvular function. Commonly, one size of valve is used in these preclinical studies, which can present difficulties with the implantation procedure and assessing valve function. Due to these potential problems, we developed a preoperative screening assessment in potential ovine candidates for prosthetic aortic valve implantation. By determining if there is a correlation between conscious and anesthetized echocardiographic examinations, an improvement in surgical confidence can predict that the animal is deemed a suitable candidate for a particular size of prosthetic valve for implantation prior to subjecting the animal to anesthesia and surgery.

METHODS: A total of 53 crossbred sheep (Ovis aries), male and female, 10-37 months of age, weighing between 41 and 77 kg, underwent conscious echocardiography and a subset of 29 of these animals underwent echocardiographic assessment under anesthesia for a preoperative valve size comparison in these animals prior to surgical prosthetic aortic valve implantation. Using 2D echocardiographic assessment, left ventricular outflow tract (LVOT) dimensions were assessed.

RESULTS: The mean paired difference between anesthetized and conscious LVOT diameter measurement was -0.87 mm (p = 0.0066, standard deviation 1.598, 95% confidence interval, -0.4796, -0.26378, n = 29).

CONCLUSION: This pilot study evaluation revealed that conscious echocardiographic assessment can play a role preoperatively in selecting potential candidates for surgical prosthetic aortic valve implantation, thereby minimizing the potential in prosthetic-native annular mismatching, which can contribute to altered LVOT function.