Latent abnormalities of sinus node function in patients with organic heart disease and normal sinus node on clinical basis

Sinus node (SN) function was analyzed in 22 patients (mean age: 46.2±12.9 years) with organic heart disease and normal SN on clinical basis (group I) and in 20 normal subjects (mean age: 43.9±15.6 years), (control group). Sinus cycle length (SCL), corrected sinus node recovery time (CSRT) and sinoatrial conduction time (SACT) were analyzed. After the control study, autonomic blockade (AB) was induced by i.v. propranolol (0.2 mg/Kg) and atropine (0.04 mg/Kg). Measurements of SCL, CSRT and SACT were then repeated. The mean SCL values were very similar in the two groups during the control state and after AB. There were no significant differences in SACTs between the two groups during the control state or after AB. On the contrary, the CSRT of group I was significantly longer than that of control group during the control state (344.8±78.9 versus 262.2±46.3 msec, P