Effects of dilating the canine pulmonary annulus with two balloons doppler ultrasound and postmortem findings

Simultaneous inflation of two balloons may be necessary for balloon dilation valvuloplasty in patients with a large annulus. We examined the cardiovascular effects of dilating the pulmonary annulus with two balloons in 18 normal dogs using pulsed Doppler ultrasound and gross and microscopic examination. When the ratio of the cross-sectional area (CSA) during dilation to the CSA of the pulmonary annulus was between 1.04 and 1.28, there was valvar regurgitation in only one dog, in which catheter manipulation was complicated by heartworms, and damage was confined to intimal changes. (The dog was killed 24 hours after dilation.) With ratios between 1.67 and 1.76 (equal to the CSA of a single balloon with a diameter 33% greater than the annulus), there was trivial or mild tricuspid or pulmonary regurgitation, and anatomic changes were more prominent but still superficial. Two animals killed after nine days had resolution of valvar regurgitation and healing damage. With CSA ratios greater than 2.00 or with balloon rupture, myocardial damage and laceration of the pulmonary arteries resulted. Simultaneous inflation of two balloons within the right ventricular outflow tract with CSA ratios of up to 1.76 results in minimal cardiovascular trauma.