Surgery of mitral incompetence.

MITRAL valve disease has for many years been accepted as the commonest sequel of rheumatism, both clinically and pathologically. The development of stenosis has never been in question. Such has not been the case, however, with incompetence, though as long ago as I849 Hope first drew attention to this condition. The existence of mitral incompetence as an entity or even as an important component of the disease was soon challenged and early in this century, largely through the teachings of Graham Steell (i906), Sir James McKenzie (i9i6), Cabot (1926) and Sir Thomas Lewis (I933), the diagnosis of mitral incompetence fell into disrepute. With the development of cardiac surgery, however, mitral incompetence has once more come into its own. Three major haemodynamic disturbances of the mitral valve have now been recognized. Pure mitral stenosis is the commonest and most readily recognized clinically and pathologically (Wood, I954). The valve leaflets are fused at the commissures and though the chordc and papillary muscles are diseased the valve mechanism is usually not grossly abnormal. The condition is generally amenable to closed-heart surgery with some form of mechanical dilator. Pure mitral incompetence is the least common and is not difficult to diagnose. Deficiency of valve leaflet tissue, dilatation of the annulus or a combination of both is generally present, but the valve mechanism remains relatively normal so that repair under cardiac by-pass is generally possible. The combination of stenosis and incompetence is frequently encountered but varying amounts of each component produce a spectrum of hbmodynamic conditions. On the one hand dominant stenosis with minimal incompetence lends itself to closed-heart surgery, whereas dominant in-