A Clinical and Spirometric Assessment of Airway Resistance in Rheumatic Heart Disease

T HE incidence of bronchitis in mitral stenosis is thought to be higher than normal (Wood, 1954), and although dyspnoea is the most prominent symptom it is frequently accompanied by cough and wheezing. It is possible that chronic congestion of the bronchial mucosa may predispose to infection of the bronchial tree, and that swelling and oedema of the mucosa may increase the airway resistance and give rise to wheezing. It is difficult to separate the effects of congestion of the bronchial veins from that of the pulmonary veins as their relationship to the bronchi and to each other is so close. The intense dyspnoea and wheezing of cardiac 'asthma' is associated primarily with left ventricular failure and therefore it appears probable that increased airway resistance can result from congestion of the lesser circulation alone. In this study, patients with mitral valve disease were investigated for symptoms and signs of bronchitis and wheezing, and the expiratory flow rate was used as a measure of airway resistance. The effect of exercise on the expiratory flow rate was also measured, as it was expected that the increase in intrathoracic blood volume after exercise, previously noted by Ball et a/. (1952), would result in an increase in airway resistance. In addition to the expiratory vital spirogram, the vital capacity was recorded, but only before exercise.