Morphometric analysis of fossa ovalis in rheumatic heart disease.

Background: Rheumatic heart disease is an important cause of valvular disease in India, with resultant alterations in the interatrial septum and fossa ovalis. Morphometric details of fossa ovalis may help in its localization during transseptal catheterization so as to prevent complications.
Methods and Results: Autopsy heart specimens of rheumatic heart disease (n=30) and non-cardiac death (n=30) patients between 15-45 years of age were studied as case and control group, respectively. The dimensions of fossa ovalis and interatrial septum were measured. The ratio of area of fossa ovalis to septum was calculated. Case group showed a significant increase in surface area of septum and fossa as compared to control group. The septal area was significantly increased in 15-30 years and 31-45 years groups, specially females in the former group. The fossa area was increased only in 31-45 years age group. The ratio of area of fossa to septum was not statistically altered in cases versus controls. Case group, specially females of 15-30 years, showed a significant horizontal orientation of fossa as compared to controls. Cases having both mitral and aortic stenosis showed highest increase in the areas of fossa and septum, as also the most horizontal orientation of fossa.
Conclusions: The enlargement of the septal area begins at an early age in rheumatic heart disease along with initial hemodynamic and valvular alterations. There is a categorical horizontal orientation of fossa ovalis in these cases. Varying dynamics in stenotic and regurgitant valves leads to varying morphological changes in dimensions of fossa ovalis and septum.