Monophasic action potential duration at the crista terminalis in patients with sinus node disease

Background: The repolarization properties of the crista terminalis (CT) cells have not been elucidated in patients with sinus node disease (SND). In the present study a new technique of recording the monophasic action potential (MAP) at the CT was used to examine the repolarization of the right atrium (RA) in SND patients. Methods and Results: Symptomatic SND (n=13) patients and age-, sex-matched control patients (n=13) were tested. The MAP duration (MAPD) at a basic cycle length of 600 ms was recorded at the CT in the superior vena cava-RA junction and at the middle-anterior RA with the effective refractory period (ERP) at the high RA. In 6 controls and 4 SND patients, the effect of adenosine triphosphate on the MAPD was examined. The MAPD at the CT exceeded that at the middle- anterior RA in both groups. The MAPD at the CT in the SND group was significantly prolonged compared with the control group (CT: 358±39 ms vs 289±43 ms). Between the SND and control groups, the MAPD at the middle-anterior RA (278±36 ms vs 265±39 ms) and ERP (294±42 ms vs 266± 41 ms) did not differ. Both the corrected-sinus node recovery time and sinoatrial conduction time were better correlated with the MAPD at the CT than the MAPD at the middle-anterior RA and ERP. Adenosine triphosphate shortened the MAPD, which was augmented at the CT in the SND patients. Conclusion: A novel method of estimating the MAP at the CT revealed the characteristics of atrial repolarization in SND patients.