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Vectorcardiograms obtained with the Frank lead system were recorded in 258 healthy subjects (139 men, 119 women) and were classified according to QRS loop patterns. Sex and age effects on the vectorcardiograms were studied. We classified the vectorcardiograms into 4 types according to the frontal axis of the maximum QRS vector (A≧60>B≧30>C≧10>D). Type B was frequent among young persons and the number of persons with type C increased with aging. The magnitude of the maximum QRS vector diminished with aging in both sexes. The axis deviated horizontally and posteriorly in men and horizontally in women. The magnitude of the maximum T vector was larger in men than in women. The axis was more anterior in men than in women. The axis of the 20-msec QRS vector deviated from the right anterior to the left anterior. The terminal QRS vector demonstrated no sex or age defference. The percentage of the QRS Bite increased with aging.

Vectorcardiograms were recorded with the Frank lead system during laparoscopy. Pneumoperitoneum produced the following significant vectorcardiographic changes: (1) The maximum spatial QRS vector increased in magnitude and shifted horizontally and slightly anteriorly. (2) The L/W ratio of the frontal QRS loop decreased. (3) The scalar data of each X, Y, Z lead of the QRS loop increased. In particular, the increases in R of all three leads and in S of lead Z were significant. These results suggest that the changes in the cardiac anatomic position due to lift of the diaphragma and a decrease of left ventricular end-diastolic volume might produce these vectorcardiographic changes during laparoscopy.

The effects of oral administration of propranolol on the electrocardiogram (ECG), vector-cardiogram (VCG) and plasma potassium levels were studied in the following groups: healthy controls, and patients with neurocirculatory asthenia (NCA), ischemic heart disease (IHD), hypertension and persistent juvenile T wave pattern. ECG and VCG were taken before, 30, 60 and 90 minutes after oral administration of propranolol in a single dose of 10mg. The results were as follows: 1) RR, PQ and QT intervals were prolonged while the rate-corrected QT interval was shortened in each group. 2) The amplitude of the T wave and the magnitudes of spatial maximum T vector and of ventricular gradient (V.G.) were increased in the healthy control group. 3) In the NCA group, which was characterized by a low T wave, small T loop, small V.G. and posteriorly directed V.G. before propranolol administration, the T wave, T loop and V.G. were enlarged and V.G. was rotated toward anteriorly. 4) In the IHD group, which was characterized by a low T wave and small T loop and V.G., the changes were unremarkable after the administration of propranolol. 5) In the well controled hypertensive group the effects resembled those of the healthy control group. In the hypertensive group without sufficient treatment, the effects were similar to those of the IHD. 6) In the persistent juvenile T wave group, a typical pattern was the location of the T loop and V.G. in the left posterior quadrant. The drug rotated the T loop and V.G. anteriorly. 7) Little change was found in the R wave amplitude and spatial maximum QRS vector in each group. 8) Plasma potassium level was not effected by the drug. 9) No undesirable effects were seen during the study. 10) The maximum effects were obtained within 60 to 90 minutes after the administration of propranolol. From the above results, propranolol appears to be useful in differentiating T wave changes associate with increased beta-sympathetic tone from changes due to other causes.