[Functional state of the sinoatrial node in patients with intraventricular block]

The function of sinus node (SN) was studied in 101 subjects with intraventricular blocks (IVB) and 30 controls. The patients with IVB showed a significant increase in the corrected time of SN function recovery and that of sinoatrial conduction both before and after medicamentous++ autonomic block, as compared to the controls. In general, signs of SN dysfunction were detected in 47 (46.5%) subjects with IVB. In 18.8% of the examinees, SN dysfunction was due to abnormal autonomic exposures, 27.7% had abnormalities in SN proper or perinodal tissue. ++Tachy-bradycardia was found in 53.5% patients with the sick sinus syndrome and IVB, 25% had concurrent atrioventricular conduction disturbances. A concomitant SN lesion was common in patients with IVB. One should take into account a type of this syndrome and the status of atrioventricular conduction when the optimal conditions of continuous electrical cardiostimulation are applied to patients with IVB and clinical signs of the sick sinus syndrome.