Right atrium and superior vena cava pressure measurements in a novel animal model to study one and a half ventricle repair as compared to Fontan type procedure

Abstract

Background & Objectives: To evaluate the advantages of the one and a half ventricle repair on maintaining a low pressure in the inferior vena cava district. Also evaluate the competition of flows at the superior vena cava – right pulmonary artery anastomosis site, in order to understand the hemodynamic interaction of a pulsatile flow in combination to a laminar one. 

Materials & Methods: Adult rabbits (n=30) in terminal anaesthesia with a follow up of 8 h were used, randomly distributed in three experimental groups: Group 1: animals with an anastomosis between superior vena cava and right pulmonary artery, as a model of one and one half ventricle repair; Group 2: animals with the cavopulmonary anastomosis followed by clamping of the right pulmonary artery proximal to the anastomosis; and Group 3: sham animals. Pressures of superior vena cava and pulmonary arteries were afterwards measured, in a resting condition as well as after induced pharmacological stress test.

Results: In Group 1, superior vena cava pressure was significantly higher, while venous pressure in the inferior vena cava – right atrium district was constant or lower in comparison with the other groups. After stress test, the pressure in the superior vena cava and the heart rate both increased further, but the right ventricular, right atrial and pulmonary artery pressures remained similar to the values in a resting condition. This proved that the inferior vena cava return was well-preserved, and no venous hypertension was present in the inferior vena cava district even after stress test (good exercise tolerance).

Conclusion: One and one half ventricle repair can be considered a good surgical strategy for maintaining a low pressure in the inferior vena cava district with potential for right ventricle growth, restoring the more physiological circulation in borderline or failing right ventricle conditions. The experiment presented a positive finding in favour of one and one half ventricle repair, as compared to Fontan type procedure.