Cardiac and respiratory involvement in advanced stage Duchenne muscular dystrophy

Abstract

This study aimed to describe myocardial involvement, respiratory impairment and pulmonary blood flow abnormalities in advanced-stage Duchenne muscular dystrophy (DMD). Twenty-one wheelchair-bound patients, aged from 10 to 24 yr, underwent electrocardiographic and echocardiographic examination, conventional spirometry, diurnal arterial blood gas analysis, and nocturnal polysomnography (SaO2 monitoring). Diagnosis was confirmed by neurological examination, dystrophin analysis at protein and DNA level. Patients were classified into two groups: group A normoxemic (14 cases) and group B with nocturnal hypoxemia (seven cases). Group A was further split into two subgroups, one without, and one with, left ventricular dilation (A1 = nine patients, end diastolic volume (EDV) = 51 ml m-2, ejection fraction (EF) = 56 per cent; A2 = five patients, EDV = 112 ml m-2, EF = 32 per cent; P < 0.05). Left ventricular regional wall motion abnormalities were found in 55, 40, and 43 per cent of groups A1, A2, and B patients respectively. Analysis of pulsed Doppler pulmonary data highlighted a significant reduction in corrected time to peak velocity in group B patients, when compared with control, A1, and A2 groups respectively. In group A, we observed a direct correlation between ejection fraction and corrected time-to-peak velocity. Two patterns of cardiac involvement may be recognized in advanced-stage DMD: left ventricular wall motion abnormalities and dilated cardiomyopathy. Doppler data which could suggest pulmonary hypertension may be observed in patients with dilated cardiomyopathy, and in patients with nocturnal hypoxemia. Therefore, in the management of advanced-stage DMD, a careful diagnosis of the heart-lung relationship should be performed, and both conventional treatment of heart failure and ventilatory therapy are necessary to improve the quality of life and survival in these patients.