Pathology of the cardiac conduction system in myotonic dystrophy: A study of 12 cases

Abstract

In 12 autopsy cases of myotonic dystrophy, the most frequently observed histopathologic lesions of the cardiac conduction system were fibrosis, fatty infiltration and atrophy. Fibrosis involved the sinus node in 6 cases, atrioventricular (AV) node in 7, AV bundle in 8, bundle branches in 10 and ventricular myocardium in 11. Fatty infiltration was observed in the sinus node in two cases, AV node in two, AV bundle in six, bundle branches in one and ventricular myocardium in nine. Atrophy was prominent in the AV bundle in five and bundle branches in eight. Lymphocytes infiltrated the conduction system in three cases and were associated with myotonic dystrophy in two and varicella myocarditis in one. Ventricular myocytes were hypertrophied in seven cases, vacuolated in three and exhibited disarray in two. The distribution and extent of conduction system lesions tended to correspond to antemortem electrocardiographic abnormalities, including prolonged PR interval in six cases, intraventricular conduction delay in six and bundle branch block in four. Cardiac involvement by myotonic dystrophy may have contributed to sudden death in four cases.

Re-entry Circuit in Ventricular Tachycardia Due to Focal Fatty-fibrosis in a Patient with Myotonic Dystrophy

“…Furthermore, histological changes are also seen in the working myocardium (16). Nguyen et al reported that fibrosis of the ventricular myocardium was seen in eleven, fatty infiltration was seen in nine, and cardiomyocyte hypertrophy was seen in seven out of twelve autopsy cases of myotonic dystrophy (15). These results suggest that fatty-fibrosis may become a point of origin of ventricular arrhythmia.…”

“…Conduction disturbance is a well-known cardiac involvement in patients with DM1 because fibrosis and fatty infiltration are often seen in the conduction system (15). Furthermore, histological changes are also seen in the working myocardium (16).…”

The tight junction protein CAR regulates cardiac conduction and cell–cell communication

“…By itself, the minor reduction in size in the absence of fi brosis or fatty infi ltration as compared with patients with AV disease could not explain the severity of the arrhythmia ( 24 ).…”

Taquicardia ventricular como expresión de Distrofia Miotónica tipo 1

“…Las anomalías de conducción resultan de la hipertrofia de miocitos, fibrosis, infiltración grasa focal e infiltración linfocítica, lo que puede ocurrir en cualquier lugar del sistema de conducción, incluido el sistema HisPurkinje 13 . La prolongación del PR afecta al 20-40% y el ensanchamiento del QRS ocurre en el 5-25% 12 .…”