Orthogonal electrocardiographic study on progressive muscular dystrophy of the Duchenne type.

An attempt was made to investigate the incidence and significance of high frequency notches and slurs on the QRS complex in patients with progressive muscular dystrophy of the Duchenne type (PMD). The patients were classified into eight stages from the most mild, S(1), to the most severe, S(8), according to Swinyard-Deaver's criteria. Cases where the sum of high frequency notches in the combined leads exceeded none were generally limited to those more advanced than stage S(4). Also, the sum of the notch count tended to be higher in S(5) to S(6) than in the remaining groups and to be lower in the milder cases, S(1) to S(4), and most severe cases, S(7) and S(8). It should be emphasized that cases in groups S(7) and S(8) who had a history of congestive heart failure and/or developed congestive heart failure during the observation period, tended to show a smaller number of notches. High frequency slurs showed almost the same tendencies as the high frequency notches. It is thus anticipated that a significant increase or decrease in the number of notches and slurs on the QRS complex may be suggestive of more intense myocardial derangement.