The Journal of Thoracic and Cardiovascular Surgery, Vol 77, 685-690, Copyright © 1979 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Evaluation of right atrial-pulmonary artery conduits for tricuspid atresia. Experimental study
RJ Shemin, WH Merrill, JS Pfeifer, DM Conkle and AG Morrow
Blood flow through right atrial-pulmonary artery (RA-PA) conduits was
investigated. Experiments were designed to evaluate the pumping function of
the right atrium, effects of the atrial versus ventricular pacing site, the
necessity of a valve within the conduit, and the effect of
positive-pressure ventilation on conduit flow. Twenty foxhounds were
subjected to silicone patch closure of 90 percent of the tricuspid valve
orifices to create stenosis. Ten dogs successfully underwent RA-PA shunting
with a conduit with paralled limbs, one containing a prosthetic valve. The
proximal main pulmonary artery was ligated to ensure total diversion of
blood via the conduit. Valved and nonvalved conduit flow was significantly
correlated with right atrial pressure (RAP): r = 0.95, p less than 0.05; r
= 0.98, p less than 0.01, respectively. There was no significant effect of
increasing heart rate (p = 0.19), atrial versus ventricular rhythm (p =
0.28), or the presence of a valve (p = 0.63). Increasing tidal volume
resulted in increasing tidal conduit flow (expiration-inspiration) (r =
1.0, p less than 0.01), but mean flow was unaffected. Therefore, RAP is the
most important factor influencing conduit flow. The absence of a valve,
ventricular rhythm, and tachycardia did not significantly alter flow in
this acute experimental model.
