New technique for angiographic visualization of membraneous subaortic stenosis.

A new technique is described for visualizing the subvalvular chamber of discrete membraneous subaortic stenosis. A Lehman ventriculography catheter is positioned so that its side holes lie within the chamber while its tip passes through the stenotic orifice into the body of the ventricle. A small amount of contrast injected directly into the subvalvular chamber outlines the membrane clearly. During diastole the contrast refluxes into the body of the ventricle, thus outlining the site and size of the stenotic orifice. Four patients were studied successfully. The most common type of fixed subaortic stenosis is the membraneous type. A fibrous membrane extends across the outflow tract I-20 mm below the aortic ring. It is attached to the septum and anterior leaflet of the mitral valve and forms the floor of a subaortic chamber (Reis et al., I971). A reliable diagnosis can be made only by cardiac catheterization. Indications for operation and the type of operation depend not only on the size of the pressure gradient but also on the anatomy of the stenosis. The latter is usually shown by an injection of a large bolus of contrast material into the body of the left ventricle (Baltaxe, Moller, and Amplatz, 1970; Baron, I971). The membrane shows as a thin translucent line below the aortic valve ring. However, visualization of the membrane is of variable quality and few details of the anatomy of the subvalvular chamber are obtained. This report describes a method for showing the anatomy by injecting small amounts of contrast directly into the subaortic chamber. Technique The Lehman ventriculography catheter (U.S. Catheter Corp. Cat. No. 5470) appears most suitable in our experience. It has several side holes several cm behind a thin solid tip. Because the side holes are not in a single plane, it is not the best catheter for determining the anatomical level of the pressure gradient. However, it permits a careful positioning of the side holes within the subvalvular chamber with little risk of losing an often hard-gained entry into the left ventricle. If the subaortic chamber is shallow, the side holes are positioned to straddle the aortic valve. Contrast, I to IO ml, is injected by hand or machine. In the most recent case we used the Contrac injector (Siemens) which permitted the injection to be confined to diastole (Schad et al., FIG. I Patient i. Frame from cineangio-gram (left anterior oblique view; diastole) shows membranous …