Non-invasive assessment of electrophysiological effects of histamine infusion in mam

The electrophysiological changes induced by sequential infusion of histamine (H) (0.4 and 1.0 mcg/kg/min for 10 min each) were investigated by conventional ECG and High Resolution ECG (H.R.ECG). The latter permits external non-invasive recording of the potentials generated in the cardiac conduction system. H was infused i.v. in 5 normal volunteers with a mean age of 30 years. H infusions were begun with 0.4 mcg/kg/min and continued for 10 min. After a 60 min recovery period a second 10 min infusion (1 mcg/kg/min) was administered. In man H produced a dose-dependent increase in heart rate, a significant depression of the ST-T complex, and a depression in STJ point. The QRS complex duration was unmodified. H.R.ECG showed significant changes in the morphology and voltage of the atrial activity. The electrophysiological effects disappeared within a few minutes after discontinuing the infusions of H.