The electrocardiograms recorded on 40 patients with the Duchenne type tf ptogiessite muscular dystrophy were analyzed. A first EKG of serial EKGs from each patient was used for the statistical analysis. The ages of the patients at the first obser' aticn ranged from 5 to 20, with a mean age of 11.4. The EKGs were analyzed with reference to the normal standards for the EKG of the Japanese children (6∼11 years) that were proposed by Kuriyama. The other normal standards for children including the ones proposed by Shirai, Ziegler, and Alimurung were referred to, when necessary. Sequential changes which occurred during 0.5 to 2.5 years follow-up periods were analyzed in 37 cases in which serial EKGs were available. EKGs were being taken with a frequency of at least every 6 months.
With the analysis of the 40 EKGs representing each patient, 87.5 per cent had some EKG abnormalities, though the findings such as sinus tachycardia, sinus arrhythmia, and slight deviation from the normal range of P-R or QRS interval were not counted as abnormal. Sinus tachycardia (>100/min.) was found in 9 (22.5%), and significant sinus arrhythmia was found in 2 (5%). In one patient atrial and ventricular premature beats were observed concomitantly.
A P-R interval equal to or shorter than 0.11 sec. was observed in 6 (15.0%), including 5 with 0.11 sec. and 1 with 0.10 sec. A slightly prolonged QRS interval was observed in 6 (15.0%), including 5 with 0.10 sec. and 1 with 0.11 sec.
The commonest abnormality was an increased R/S ratio in the right precordial leads; R/SV1 exceeding 1 was observed in 19 (47.5%), tlit exceeding 1.5 in 12 (30.0%), and that exceeding 2 in 8 (20.01).
The next common abnormality was the presence of R' in the right precordial leads. When an R' in V1 was present regardless of its amplitude, it was classified as incomplete right bundle branch block (RBBB), provided that the QRS interval was less than 0.12 sec.; incomplete RBBB defined as such was present in 14 (35.0%), among which an R'V1 greater than 5.0 mm was observed in 3 (7.5 9, ).
A high R in V1 exceeding its upper normal limit 12.0 mm (according to Kuriyama) was present in 4 (10.00), and an abnormally small S in Yi less than its lower normal limit 4.0mm (Kuriyama), regardless of presence or absence of R'V1, was present in 15 (37.5%). Also, the mean of RV1 of the 40 cases was close to the mean of normal, while the mean of SV1 was significanlty smaller than the mean of normal. Therefore, a short Svi rather than a high RV1, appears to be a major deviation from normality, contributing to an increased R/S ratio in V1.
Abnormal Q waves in I, aVL, V4, V5, and/or V6 were observed in cases with relatively advanced muscle function impairment; Q/R ratio greater than 1/3 in I, V4, V5, and, or V6, or a QS deflection in these leads, a pattern simulating a lateral wall myocardial infarction, were observed in 3 (7.5%). When Qv5 greater than 4.0 mm (upper normal limit by Kuriyama) was used as a criterion, regardless of Q /R ratio, it was found in 5 (12.5 %), including 3 cases with mild impairment of muscle function. In contrast, high voltage in the left precordial leads was rare, and there was only one case with a Rv5 exceeding 40.0mm. The mean amplitude of RV5 of the present series was 16.95 mm, and this value was significantly lower than the mean of normals (24.70 mm for 11 years old boys).
There were 3 cases in which T wave changes were found. The changes consisted of flat T in V5 and V6 or small inverted T in V4 through V6, which were found also in relatively advanced cases.
