Sub-clinical rheumatic carditis.

Since the operation of mitral valvotomy was introduced, various attempts have been made to explain the high incidence of histologically active lesions in biopsies of the left atrial appendages removed at operation, in view of the low incidence of active lesions found at necropsy in clinically inactive cases of rheumatic heart disease. Several clinico-pathological studies have been made in biopsy series (Kuschner et al., 1952; Catto et al., 1952; Biorck et al., 1952; Sabiston and Follis, 1952; McNeely et al., 1953; Manchester et al., 1955; Clark and Anderson, 1955; Elster and Wood, 1955), but no correlation has been found between the presence of histologically active lesions and the usual clinical and laboratory criteria of rheumatic activity. Most of the figures on the incidence of active lesions in left atrial appendages in biopsy series refer to the presence of Aschoff nodules, although there are considerable differences in what are interpreted as Aschoff nodules. Little attention has been paid to mucoid changes and cellular infiltrations in the subendocardium, which also appear to be part of the rheumatic process. The histological criteria used for rheumatic activity in this series have been described elsewhere (Lannigan, 1959). The following is a description of a clinico-pathological correlation in a series of 175 patients who had mitral valvotomy and a necropsy series of 61 cases of rheumatic heart disease.