ACUTE, REVERSIBLE TRICUSPID INSUFFICIENCY - CREATION IN CANINE MODEL

Relatively few methods have been described for the creation of valvular insufficiency in an animal model. Those presented involve limitations such as permanent destruction of the valves or lack of control over the degree of regurgitation produced. We describe a method of acute reversible tricuspid insufficiency that can be easily created and controlled in anesthetized dogs. The model employs a wire spiral that is advanced through the atrioventricular canal from the right atrium. The spiral causes regurgitation by preventing complete apposition of the valve leaflets while permitting retrograde flow to occur through the spiral lumen. The degree of regurgitation can be controlled by the use of spirals of different sizes. Creation of tricuspid insufficiency is demonstrated by the onset of right atrial pressure V waves, a "ballooning" of the right atrium during ventricular systole, palpation of an atrial thrill, or by color Doppler echocardiography. In 14 dogs, right atrial pressure increased from a control value of 9 +/- 3 (mean +/- SD) mmHg to 10 +/- 3 and 12 +/- 3 mmHg, respectively, with spirals of 1.5 and 2.2 cm in diameter (both P < 0.05). With the 2.2-cm spiral, aortic blood pressure decreased from a control value of 104 +/- 20 to 83 +/- 17 mmHg (P < 0.05), and cardiac output decreased from 73 +/- 26 to 59 +/- 19 ml. min-1.kg-1 (P < 0.05). This model is reversible, allows repeated trials of various grades of regurgitation, does not require ventriculotomy, and is relatively nonarrhythmogenic.