[Cardiac autonomic blockade in sinus disease and indication for a pacemaker]

Functional autonomic blockade (FAB) with metoprolol (0.2 mg/kg body weight) and atropine sulphate (0.04 mg/kg) was carried out in 23 patients, 20 to 81 years old (mean age 61 years) with symptomatic sick sinus syndrome with clinical indication for permanent pacing. Several measurements were determined before and after FAB, 7 had normal intrinsic heart rate (IHR) and 16 abnormal. With normal IHR, 3 had severe autonomic regulation disturbances and in only two patients the corrected sinus nodal recovery time (SNRTC) and the sinoatrial conduction time (SACT) were prolonged after FAB. On the 16 patients with abnormal IHR only 4 had severe extrinsic autonomic influence and 15 had SACT and SNRTC prolonged after FAB. All measurements were determined by standard electrocardiographic surface tracings. Indications for permanent pacing were reduced to intrinsic sick sinus syndrome and bradycardia with severe autonomic disturbances in symptomatic patients.