A Three-bladed Dilator for Trans-ventricular Mitral Valvotomy.

Since Andrew Logan first described the use of an expanding dilator introduced through the left ventricle for the relief of mitral stenosis this method has been widely accepted. The underlying principle is to use a two-bladed dilator, guided into and opened in the stenosed mitral valve, exerting a disruptive force causing separation of the fused commissures of the valve leaflets. This disruptive force must be exerted in two planes only, so that there is at least the theoretical possibility of tearing a valve cusp. In a small personal series of cases, therefore, a three-bladed dilator, together with the index finger used as a fourth dilating agent, has been used since December 1958.