Effects of amyl nitrite in aortic valvular and muscular subaortic stenosis.

INHALATION of amyl nitrite causes abrupt vasodilatation and increase in cardiac output and intensifies the murmur of aortic stenosis.1 The transaortic systolic pressure gradient increases because of the increased ejection rate through the stenotic orifice. In muscular subaortic stenosis this effect is particularly marked,2-6 not only because of the increased ejection rate but also because the diminished heart size apparently causes increase in the severity of obstruction in the outflow tract. Glyceryl trinitrate has a similar effect.7 Amyl nitrite is a convenient stimulus for increasing the pressure gradient in muscular subaortic