The circadian profile of extrasystolic arrhythmia: its relationship to heart rate and blood pressure.

This paper aims at examining whether there is an association between the circadian patterns of systolic blood pressure, heart rate and the incidence of ventricular ectopic beats, as well as to confirm that reducing the blood pressure by a diuretic may also reduce the ectopic frequency. Thirty-four ambulatory patients with ventricular ectopic beats and a systolic blood pressure of 131.33 +/- 17.46 mmHg had a 24-hour Holter electrocardiographic and blood pressure monitoring following 1 week off any antiarrhythmic and antihypertensive treatment. Then they received for one week a standard diuretic combination (amiloride 5 mg + hydrochlorothiazide 50 mg) at a dose depending on their systolic pressure value and their monitoring was repeated. The mean hourly values of systolic blood pressure, heart rate and ventricular ectopic beats were "normalized", i.e. expressed as (x-x)/SD, taking each patient's 24-hour average as zero and his own standard deviation as the unit of measurement. As a group, there was an independent positive correlation between blood pressure and ectopic beats, while the heart rate was a nonsignificant negative factor for ectopic beats. On an individual level, however, an independent positive significant correlation between blood pressure and ectopic beats was found in only 8 cases, with a negative one in 4 cases. While the blood pressure of the group ranged symmetrically around its daily average value, the corresponding ectopic beat curve was highly asymmetric, with a very high incidence (up to 2.56 +/- 0.52 SD) for a rather short time (only 9.41 +/- 3.56 hours above average) and a low incidence (up to 1.26 +/- 0.49 SD) for the remaining 14.59 hours below average. Sudden rises in ectopic beat (greater than 1 SD/hour) occurred 1 to 6 times per day in each individual, significantly (P less than 0.01) more often (20.31%) with a high (greater than 1 SD) blood pressure than with a low (less than -1 SD) one (8.99%) with intermediate frequencies at intermediate pressures. After treatment with the diuretic, the systolic blood pressure was reduced, the heart rate increased and the ventricular ectopic beat incidence reduced (significant changes). The mean change in systolic pressure in 25 patients with a reduction in ectopy was a significant (P less than 0.01) decrease (-5.21 +/- 8.70 mmHg) while in the remaining 9 cases there was a non significant increase (+1.68 +/- 7.63 mmHg). The heart rate was higher in both subgroups.(ABSTRACT TRUNCATED AT 400 WORDS)