Autonomic sinus node dysfunction and its treatment.

The clinical, electrocardiographic, pharmacologic, electrophysiologic and Holter monitoring findings are described in four patients with autonomic sinus node dysfunction and one patient with autonomic binodal disease. All showed cerebral symptoms, and had attacks of dizziness, weakness, near-syncope or syncope. After a pharmacologic autonomic blockade with propranolol and atropine, all patients had normal intrinsic heart rates. Electrophysiological studies revealed normal corrected intrinsic node recovery time (less than or equal to 240 msec) a gradual return to the basic cycle length in the secondary postpacing cycles after autonomic blockade, and no intrinsic paroxysmal atrioventricular block. Continuous ECG monitoring (1-3 X 24 hours) revealed severe sinus bradycardia, SA-block, severe sinus arrest, cardiac standstill, atrial fibrillation and in two patients associated AV-block. Autonomic blockade with electrophysiological studies exclude the intrinsic involvement of the sinoatrial and atrioventricular node. Holter monitoring is the best method for assessing the autonomic neurovegetative component of dysrhythmias. Therapy regarding isolated autonomic sinus node dysfunction depended on the pathomechanisms of rhythm disorders: two patients received permanent pacemakers, antiarrhythmic drugs were applied in the case of two patients, and etiological treatment in the case of one. During the follow-up, all patients became symptom-free.