Mechanical principles in the surgery of aortic and mitral incompetence.

The operative treatment of valve stenosis has now been shown, as a result of large numbers of successful operations, to be very satisfactory. The operative treatment of valve incompetence is, however, quite another matter; in spite of various ingenious efforts no satisfactory method has yet been introduced. My own experience is that the mortality of these procedures is high and the results bad; fronr reading what has been written and from listening to the presentation of papers at society meetings I have no evidence that the results are any better in the hands of other surgeons. Indeed, at present it is difficult to feel justified in advising any patient who is suffering from predominant valve incompetence to submit to an operation for its correction. The object of this article is to record some personal experiences and to present some reasons why the methods used have failed. Every surgeon has to decide whether he will use foreign substances, fashioned as prostheses and introduced into the body. Prostheses have been designed and used to correct valve incompetence; their presence appears to be tolerated for short periods but their later fate is quite uncertain. From the vast accumulated experience of surgeons in the fate of foreign bodies introduced into other parts of the body there is little to encourage us to hope that such substances, even if composed of a plastic, will be longer and better tolerated in the interior of the heart or of the great vessels. A long, trouble-free life would appear to be very unlikely for a young patient whose heart or aorta contains such a plastic valve. Biologically the patient's own tissues should be much safer than a foreign material; our difficulty lies in the adaptation of tissue to serve as a useful functioning valve. The most popular substance has been pericardium, introduced into the heart or aorta in the form of a flap designed to correct the leakage of the incompetent valve. There are three reasons why this usually fails: (1) fibrosis and shrinkage; (2) unsatisfactory placing; and (3) the influence of the axial stream of regurgitant blood.