Physiopathology of transient ventricular occlusion during balloon valvuloplasty for pulmonic or aortic stenosis.

Hemodynamic observations were made at different cardiac levels during transient balloon occlusion at the time of aortic or pulmonary valvuloplasty in 37 patients (mean age 8 +/- 9 years); 22 had pulmonary stenosis and 15 had aortic stenosis (6 valvular and 9 discrete subvalvular types). Eighty-two tentative dilatations were performed in patients with pulmonary stenosis and 61 in patients with aortic stenosis. The hemodynamics of the right and left heart were monitored during inflation-deflation time. From selected tracings mean beat-to-beat pressures curves were constructed during occlusion-recovery time. The cycle length (RR interval) did not change significantly during occlusion, except for patients with pulmonary occlusion and patent foramen ovale, where a significant increase in cycle length (p less than 0.01) was observed during recovery time. The mean maximal increase in ventricular pressure reached 95% of basal values for the right ventricle and 58% for the left ventricle. The hypertension was retrogradely transmitted to all cardiac chambers. Angiographic observations during occlusion suggest that the atrioventricular valves and the foramen ovale, when patent, become escape orifices during occlusion, for adapting and relieving intracavitary pressures. The ventricle seems to adapt to sudden occlusion by generating hypertensive and hypokinetic contractions, with atrioventricular regurgitation.