Determination of Left Atrial Volume by Angiocardiography

Abstract

Left atrial volume and its change during cardiac cycle were studied in 49 patients with various heart diseases and 8 normal individuals by simultaneous use of cineangiocardiography at 400 fps and film changer at 6 fps. Methods Calculation of left atrial volume was performed as described by Sauter et al. assuming that the left atrium might be represented by an ellipsoid, and it was corrected for nonparallel X-ray beams in each case. Results Left atrial volume was calculated by two different methods: 1) using both A-P and lateral projections and 2) using only A-P projection. When the left atrial volume was less than about 200ml, it could be calculated from the following formula; Y = 0.55X + 0.8 where Y is the true left atrial volume and X is the value calculated from A-P projection. When the left atrial volume was more than 300ml, the value calculated from A-P projection was much the same as the value calculated from both A-P and lateral projections. As the left atrial volume became large, the length of two axes became equal especially in the lateral projection. There was a statistically significant correlation between maximal left atrial volume and left atrial cyclic volume change, but in cases with atrial fibrillation there was no significant correlation between them. There was no significant correlation between the left atrial volume and the mean PC pressure. The large left atria could be found in mitral valvular diseases, but a gigantic one was usually seen in the mitral regurgitation. In general, the left atrial volume was larger in cases with atrial fibrillation than in cases with normal sinus rhythm. In mitral valvular diseases with auricular fibrillation contraction of the left atrium was insufficient. Left atrial cyclic volume change was close to left ventricular stroke volume in mitral regurgitation with atrial fibrillation but the former never exceeded the latter in all cases. On making observation of the left atrium by using high speed cineangiography, the length of both longer and shorter axes changed parallel to its volume during cardiac cycle in cases with normal sinus rhythm, but they changed quite irregularly in cases with atrial fibrillation. In cases with mitral regurgitation, it was observed that the expansion of the left atrium was due to regurgitant flow from the left ventricle is spite of the presence of the atrial ribrillation.