THE EFFECT OF FREQUENT VENTRICULAR ECTOPI C ACTIVITY ON CEREBRAL BLOOD-FLOW IN PATIENTS WITH CORONARY-ARTERY DISEASE

Animal experiments using the microsphere method indicate a 8% reductio n of mean cerebral blood flow during parasystolic rhythm induced by ve ntricular pacing in comparison to a control group with sinus rhythm. T he parasystolic rhythm causes changes of systemic arterial blood press ure, which are comparable to the hemodynamic effects of frequent prema ture ventricular contractions. Because a reduction of cerebral blood f low induced by frequent premature ventricular beats can be assumed by the results of the laboratory investigations, cerebral blood flow was determined in a clinical study in 1 9 coronary artery disease patients and in 11 healthy, age-adjusted volunteers using the Xenon-133-inhala tion method, in order to investigate the effect of ventricular ectopic s on cerebral perfusion. Simultaneously Holter monitoring was performe d during cerebral blood flow measurements. Cerebral blood flow was est imated by the initial slope index, which is calculated from the early decay of the clearance curve, and by the mean cerebral blood flow inde x, which is calculated by the stochastic method. Grey matter blood flo w is estimated by the two-compartment analysis. Cerebral blood flow in coronary artery disease patients is reduced versus controls. The init ial slope indices were 45.2 +/- 5.1 s-1 and 57.4 +/- 7.2(-1) respectiv ely (p < 0.01). In patients with frequent ventricular ectopic activity (739/h) an additional reduction of cerebral blood flow was observed. The initial slope index was 42.6 +/- 6.3 s-1 (p < 0.01). The reduction of cerebral blood flow in coronary artery disease patients is partial ly due to the coincidence of coronary and cerebral artery disease. Fre quent ventricular premature contractions might cause an additional red uction.