Abstract 2707: Gender Differences in the Anatomy of the Interatrial Septum
Introduction: Women have faster AV nodal conduction times and shorter refractory periods than men, even after matching for age and body size. They also have a much higher incidence of AV nodal reentry tachycardia, despite having comparable rates of dual AV nodal physiology. The cause of these differences is unknown.
Hypothesis: We tested the hypothesis that females have smaller interatrial septa (ISA) and larger coronary sinus ostia (CSos) than men, independent of body size.
Methods: Seventy-five patients undergoing CT angiography were evaluated using 64-slice gated CT images. Three-dimensional reconstruction images were used to measure aortic root diameter, right atrial size, and CSos diameter. The size of the IAS was quantified by measuring the distance from the central fibrous body to the roof of the CSos. Data was obtained for age, sex, race, ejection fraction, body surface area (BSA) and the presence of hypertension and/or heart failure.
Results: The mean age of the patients was 51±14 years and 44% were female. Hypertension was present in 50% of the patients and 28% had a history of heart failure. The mean distance from the central fibrous body to the roof of the CSos was 0.89 +/− 0.32cm and the mean diameter of the CSos was 1.78 +/− 0.60cm. Older patients had a shorter distance from the central fibrous body to the roof of the CSos compared to patients < 55 years (0.74 +/− 0.31cm vs. 0.99 +/− 0.30cm, p = 0.001). This distance was also smaller in females compared to males (0.79 +/− 0.26cm vs. 0.96 +/− 0.35cm, p < 0.05). CS diameter was not significantly different in age and sex comparisons. Multivariate analysis showed that only female gender was independently predictive of a short CSos - central fibrous body distance, even with BSA included in the model.
Conclusions: In conclusion, the IAS is smaller in women than men, independent of BSA. The smaller distance between the central fibrous body and the CSos may account for the shorter PR interval, shorter AV node refractory period, and higher incidence of AV node reentry in women.