Abstract
Although the overdrive suppression test (ODST) is important in detecting sick sinus syndrome (SSS), its sensitivity is still not satisfactory. We evaluated the effect of intravenous injection of disopyramide phosphate (DP) in ODST. The subjects were 30 SSS patients (65.7±10.0 years old). If sinus node recovery time (SNRT) was<2000ms or the corrected SNRT (CSNRT) was<1000ms, ODST was repeated after DP iv (2mg/kg, ≤100mg in total). Eleven normal subjects (59.3±9.0 years old) were also studied. Although the conventional ODST was negative in 13 of the 30 SSS patients (43%). SNRT was prolonged from 1510±300 to 3400±1160ms (p<0.01), CF from 510±190ms to 2470±1470ms(p<0.01) after DP iv. in these patients. Thus, SNRT and CRT was positive in 27 of the 30 SSS patients (90%) after DP iv. SNRT and GMT were rather shortened in the normal subjects during ODST after DP iv. (p<0.01). The plasma concentration of DP examined in 9 patients was 4.1±1.0mcg/ml. No serious side effect occurred. ODST employing DP iv. is safe and seems to be highly effective in diagnosing SSS.
