Indications for Commissurotomy in Mitral Stenosis

¹ Professor of Medicine, Coordinator of Cardiovascular Instruction, University of Southern California School of Medicine, Department of Medicine (Cardiology). Diplomate American Board of Medicine and Cardiology.

In the majority of cases, cumulative effects of strain progressively handicap the heart until the patient becomes totally incapacitated. If intervention is to be of greatest value, it must come before irreversible changes in heart and related structures occur, which will in themselves limit recovery and survival of the patient.

Progressive adaptation to the altered circulation may relieve for a time symptoms most indicative of the disorder; the physician must not be misled into accepting these changes as signifying improvement. In relatively pure stenosis, the left atrium is distended and the entire lesser circulation slowed. In patients with regular heart rhythm, both left auricular pressure and pulmonary venous pressure are exaggerated in auricular systole. Ventricular diastolic filling is accompanied by typical stenotic murmurs.

Conditions which mimic mitral stenosis include chronic failure of the left ventricle, constrictive pericarditis, congenital or acquired stenosis of the pulmonary veins, pedunculated tumor of the left atrium, a free thrombus which causes intermittent obstruction, hyperthyroidism, and interatrial septal defect. Laboratory examinations are helpful for detection of rheumatic activity or subacute bacterial endocarditis (both contraindications to surgery).

Cardiac size and configuration may be estimated by percussion, cardiac fluoroscopy, teleroentgenograms and esophagrams; through palpation of the P.M.I. or through angiocardiography; and by means of unipolar lead electrocardiography. Murmurs may be studied by auscultation and phonography. Other useful measures are circulation time and estimations of cardiac output both at rest and after exercise, by ballistocardiography and cardiac catheterization (including direct entry into the left side of the heart).

For the present, multivalvular lesions are considered inoperable. Preferably, the operation should be performed when the patient is in class III (functional capacity) or in class II but rapidly approaching class III. The most important factor in scheduling the operation is the rate with which the patient's condition is deteriorating.