Effectiveness of balloon valvuloplasty for palliation of mitral stenosis after repair of atrioventricular canal defects.

Closure of a mitral valve (MV) cleft, small left-sided cardiac structures, and ventricular imbalance all may contribute to mitral stenosis (MS) after repair of atrioventricular canal (AVC) defects. MV replacement is the traditional therapy but carries high risk in young children. The utility of balloon mitral valvuloplasty (BMV) in postoperative MS is not established and may offer alternative therapy or palliation. Since 1996, 10 patients with repaired AVC defects have undergone BMV at a median age of 2.5 years (range 8 months to 14 years), a median of 2 years after AVC repair. At catheterization, the median value of mean MS gradients was 16 mm Hg (range 12 to 22) and was reduced by 34% after BMV. Before BMV, there was mild mitral regurgitation in 9 of 10 patients, which increased to severe in 1 patient. All patients were alive at follow-up (median 5.4 years). Repeat BMV was performed in 4 patients, 10 weeks to 18 months after initial BMV. One patient underwent surgical valvuloplasty; 3 underwent MV replacement 2, 3, and 28 months after BMV. In the 6 patients (60%) with a native MV at most recent follow-up (median 3.2 years), the mean Doppler MS gradient was 9 mm Hg, the median weight had doubled, and weight percentile had increased significantly. In conclusion, BMV provides relief of MS in most patients with repaired AVC defects; marked increases in mitral regurgitation are uncommon. Because BMV can incompletely relieve obstruction and increase mitral regurgitation, it will not be definitive in most patients but will usually delay MV replacement to accommodate a larger prosthesis.