INTRAVENOUS-INJECTION OF ADENOSINE-TRIPHOSPHATE FOR ASSESSING SINUS NODE DYSFUNCTION IN PATIENTS WITH SICK SINUS SYNDROME

The clinical value of rapid intravenous injection of adenosine triphos phate (ATP, Adephos Kowa # L3, CAS 56-65-5) for assessing sinus node f unction was examined in 5 patients with sick sinus syndrome (SSS) and 6 normal controls. All patients with SSS showed cardiac pauses longer than 3 s on a 24-h Holter ECG monitoring. First, after prophylactic in sertion of a temporary pacemaker in the right ventricle, overdrive sup pression test was conducted using the standard technique, and sinus no de recovery time (SNRT) was observed to evaluate the sinus node functi on. Then, 10 min later, 10 mg of ATP was rapidly injected intravenousl y, and body surface and intracavitary ECG were continuously recorded u ntil the basal state was regained The rapid injection of ATP resulted in a slight inhibition of sinus node automaticity in normal subjects, but marked inhibition was in patients with SSS associated with suppres sion of AV conduction. The longest post ATP atrial cycle (AA) interval in the intracavitary ECG showed a close inverse relationship with SNR T corrected for basal sinus length (CSNRT), according to the following formula: longest AA interval (ms) = 3.32 x CSRT (ms) +254.4 (r = 0.91 , p < 0.001). The results suggest that rapid intravenous injection is a useful tool for the diagnosis of SSS.