Takehiko Mikawa

Range of ventricular ectopic complexes in healthy subjects studied with repeated ambulatory electrocardiographic recordings

The incidence and forms of ventricular premature complexes (VPCs) in apparently healthy subjects were studied to determine long-term reproducibility of day to day variation on Holter electrocardiogram. The study included 152 men and 68 women ranging in age from 20 to 78 years who were having routine check-ups that revealed no cardiovascular abnormalities. In addition to routine measurements, Holter electrocardiography was recorded during daily life, and the total number of VPCs occurring during 24 hours was visually calculated on replayed electrocardiographic tracings. Forms of VPCs and incidence of VPCs in 10-year age groups of the subjects were also recorded. No VPCs were observed in 56% of the subjects; 93% showed less than 50 VPCs and the other 7% of the 220 subjects had greater than or equal to 50 VPCs. Forty-one of the 220 subjects returned for routine follow-up 1 year later. Repeated Holter electrocardiograms at this time showed high reproducibility of less than 50 VPCs. A small number of multiform VPCs were reproducible but paired VPCs were not. Physiologic definition of VPCs in healthy subjects appears to be clinically significant.

Magnesium Content of Erythrocytes in Patients with Vasospastic Angina

SummaryThe possibility that a magnesium deficiency might be the underlying cause of vasospastic angina (VA) and the efficacy of Mg administration in its treatment were studied. Subjects included 15 patients with VA and 18 healthy subjects as the control group. The erythrocyte Mg content was measured by atomic absorption, and serum Mg was measured by conventional chemical assay. The efficacy of Mg administration was studied in seven patients with VA. The results were as follows: a) The mean erythrocyte Mg content was less in the group with frequent episodes of angina (1.59 ± 0.11 mg/ dl) than in the group without angina (2.11 ± 0.38 mg/dl, p < 0.01) and in the control group (2.22 ± 0.29 mg/dl, p < 0.01). There was no significant difference between the control group and patients of each group with respect to serum Mg. b) Coronary arterial spasm was induced by ergonovine maleate in seven patients and was completely inhibited by the administration of Mg sulfate (40–80 mEq, hourly) in six of these patients; in the remaining patient neither obvious ST change nor chest pain occurred. Thus, it was concluded that the measurement of erythrocyte Mg content is useful to determine how easily vasospasm might occur in VA and that the administration of Mg might be developed as a new therapy for spasm associated with a low erythrocyte Mg content.