CHAPTER 6 ELECTROCARDIOGRAPHY

Summary 1. Of 161 patients with morbus caeruleus, 158 were examined by electro‐cardiography before operation. In 56 cases only standard leads were used, and 102 cases were studied with standard leads and unipolar limb and chest leads. Postoperative electrocardiography was done in 138 cases–with standard leads in 19 and with standard leads and unipolar limb and chest leads in 119 cases. Of these 119 cases, 89 had been examined in the same way before operation. 2. Arrhythmia with extra systoles was uncommon after shunt operation, only 1 patient being found to have atrial extra systoles. In another case frequent attacks of paroxysmal tachycardia developed in association with progressive cardiac enlargement and decompensation, probably as a result of excessive width of the artificial anastomosis. 3. Prolonged atrioventricular conduction time (P‐R interval) was found postoperatively in 4 cases, 3 of which showed roentgenologic cardiac enlargement after the shunt operation. 4. Broadening of the P waves occurred in only 2 patients postoperatively. By contrast, the amplitude of the P waves altered in that significant decrease was found postoperatively over the left side of the heart. No significant change in the P waves was found over the right side of the heart. 5. The mean value for the electrical axis of the QRS complex showed significant diminution in righi deviation after operation. 6. The R waves over the left side of the heart showed significant increase of amplitude after operation in the patients with tetralogy of Fallot, whereas the R waves over the right side of the heart were not significantly altered. The increased R‐wave amplitude in the left precordial leads is attributed to the increase in the work of the left ventricle following creation of the anastomosis. 7. Hypertrophy of the right ventricle was present in almost all of the series. Exceptions were patients with tricuspid atresia and a case in which the diagnosis was obscure: These patients had no or only left ventricular hypertrophy. One patient with tetralogy of Fallot had no definite hypertrophy before or after operation, which is considered to be unusual in view of the diagnosis. 8. Significant increase in the number of inverted T waves was noted after operation in the unipolar precordial leads. This change was most pronounced over the right side of the heart. Its cause could not be conclusively established.