Masahiro Shimotori

Long‐Term Follow‐Up of Patients with Sick Sinus Syndrome: A Comparison of Clinical Aspects Among Unpaced, Ventricular Inhibited Paced, and Physiologically Paced Groups

To analyze the prognosis of the sick sinus syndrome (SSS), we compared the clinical aspects among unpaced, ventricular paced, and physiologically paced patients who were followed over a long period. Unpaced intrinsic SSS was not always progressive and patients did not necessarily require permanent pacing. The incidence of concomitant AV conduction disturbance was 65.6% before pharmacologic autonomic block, (PAB), but this was significantly reduced to 31.7% after PAB. Follow‐up study of the physiologically paced groups revealed no development of either new or more than second degree AVB. The VVI group had significantly more complications (68%) than the physiologically paced groups, mainly chronic atrial fibrillation (36%) and thromboembolism (20%). In addition, cardiothoracic ratio (CTR) in the VVI group was significantly greater compared with that in the physiologic groups. Nine deaths occurred during the follow‐up period in the pacing groups, including six with VVI and three with physiologic pacing. In the VVI pacing group, heart failure and thromboembolism were most commonly the causes of death, while in the physiologic pacing groups, the causes of death were noncardiac. Although the survival rate in the ventricular paced group was not significantly different from that in the physiologic pacing groups, cardiac deaths were fewer in the latter group. Considering our clinical data, the decision to use ventricular pacing needs to be carefully weighed in patients with sick sinus syndrome, and physiologic pacing is more highly recommended. (PACE, Vol. 11. November 1988)

Comparison between ventricular inhibited pacing and physiologic pacing in sick sinus syndrome

Abstract Sick sinus syndrome (SSS) causes not only infrequent cardiac dysfunction but also systemic complication, and pacemaker implantation has been applied to prevent such an episode. Several kinds of pacemakers have been available for clinical use. However, the selection of these pacemakers has been controversial depending on the severity and character of the conduction system impairment accompanying SSS. We have already reported the long-term follow-up results in patients with SSS who had not had a pacemaker or had implanted pacemakers of various modes. 1 In that report, we found that the ventricular inhibited paced (VVI) group had significantly more complications and a greater cardiothoracic ratio after pacing in the follow-up period than the physiologically paced groups. We concluded that the decision to use VVI pacing needed to be carefully assessed in patients with SSS, and that physiologic pacing is more highly recommended. However, the study population in that report was small and the follow-up period was short. In this article, we report the results of our further study with a larger population and longer follow-up.

The effects of aminophylline on adenosine and ATP actions on sinoatrial conduction in the isolated, blood-perfused dog atrium

The effects of adenosine and adenosine triphosphate (ATP) on sinus cycle length (SCL) and sinoatrial conduction time (SACT) estimated by constant atrial pacing were studied in isolated, blood-perfused canine right atria. Adenosine and ATP were infused into the sinus node artery at a rate of 1, 2 and 4 micrograms/min. Both adenosine and ATP caused an increase in SCL and SACT in a dose-dependent manner and decreased atrial developed tension. There was no significant difference between the effect of adenosine and that of ATP on SCL and SACT. The prolongation of SACT induced by 4 micrograms/min of adenosine and ATP was significantly inhibited by a single injection of 1 to 3 mg of aminophylline, although this dose level of aminophylline did not significantly suppress the prolongation of SCL produced by adenosine and ATP. From these results it is concluded that both adenosine and ATP lengthen SCL and SACT in a dose-related manner, and that aminophylline blocks the increase in SACT much more easily than that in SCL.