Balloon Valvuloplasty Registry

BACKGROUND:

Valvular stenosis or incompetence results in an estimated 41,000 valve replacements in the United States each year. These replacements are equally distributed between the aortic and mitral valves. An estimated 60 percent of aortic valve replacements are the result of valve stenosis; 20-30 percent of mitral valve replacements are due to stenosis. The risk of operative mortality in single valve replacement ranges from 3 percent to as high as 15 percent depending upon patient characteristics. Morbidity associated with open heart procedures includes wound infection, reoperation for bleeding, and post-operative pain. Most patients with artificial valves require anticoagulant therapy for the rest of their lives and thus face the competing risks of hemorrhage and valve thrombosis/embolism. In addition, there are a number of patients with aortic stenosis who are not candidates for aortic valve replacement because of unacceptable operative risks who might be dramatically improved by balloon valvuloplasty.

The pathophysiologic processes underlying valvular stenosis at the aortic and mitral positions are quite different. Mitral stenosis is an outcome of rheumatic fever. Rheumatic fever is quite unusual in this country but it and its sequelae, rheumatic valvular disease, persist as major public health problems in the Third World. Aortic stenosis is most commonly the result of calcific degeneration of a normal tricuspid aortic valve in the elderly or the result of rheumatic fever but can also develop in a congenital bicuspid aortic valve which becomes progressively more stenotic with age and the wear of abnormal flow patterns.

The results of surgical valvuloplasty differ for mitral and aortic valves. Surgical valvuloplasty (commissurotomy) for mitral stenosis is currently a well-established and commonly used treatment for symptomatic patients with mitral stenosis. Similar attempts at repair of aortic stenosis have been largely unsuccessful. Surgical valvuloplasty for aortic stenosis has, for this reason, been abandoned in favor of valve replacement. Initial attempts at aortic balloon valvuloplasty were, therefore, undertaken in patients who were not surgical candidates; these initial efforts in a small number of patients, coming as they did in the wake of abandoned surgical attempts, were surprisingly successful in reducing gradients and increasing valve area without complications such as embolism or significant regurgitation.

Balloon valvuloplasty began with pediatric cardiologists using catheters designed for dilatation of peripheral arterial stenosis in children with pulmonic stenosis and those with coarctation of the aorta. Balloon dilatation has been quite successful with pulmonic stenosis, and is now an accepted therapeutic maneuver. It is less successful with coarctation of the aorta. As a direct outgrowth of this research, investigators have applied this procedure to mitral and aortic stenosis in adults.