Abstract
The clinical significance of sinus node recovery time (SRT) after pharmacologic autonomic blockade (PAB) was evaluated in 49 sick sinus syndrome (SSS) patients. Patients with SSS were classified into three groups according to the SRT before PAB and the change ratio of corrected sinus node recovery time (CSRT) before and after PAB as follows : Group A had an SRT before PAB of less than 5000 msec and a CSRT change ratio of less than 200 % ; Group B had an SRT before PAB of less than 5000 msec and a CSRT change ratio of more than 200 % ; and Group C had an SRT before PAB of more than 5000 msec. There is no difference of SRT between Groups A and B before PAB, while the SRT in Group B lengthened significantly (P<0.01) and was similar to Group C after PAB. Clinical findings including central nervous system (CNS) symptoms, CTR and pacemaker implantation in Groups B and C were significantly severer than those in Group A. The max R-R interval was more prolonged in Groups B and C than in Group A. Furthermore, a higher sympathetic nervous tone was noted in Group B than in Group A by the % chronotropy. In conclusion, some patients with an SRT of less than 5000 msec before PAB belonged to the severe Group ; therefore, it is useful to consider an SRT after PAB and a change ratio of CSRT for determining the clinically severe Group.
