[Shortening characteristics of the interventricular septum measured by biplane coronary cineangiograms].

The shortening characteristics of the interventricular septum may differ from those of the free wall because the contraction of the right ventricle can interfere with the motion of the interventricular septum. Biplane left coronary cineangiography were performed for 19 normal subjects, eight patients with old anteroseptal infarction and seven patients with hypertrophic cardiomyopathy. The coordinates of the points on the left coronary artery were measured, and the spatial distances (segment length) between any of those two points were calculated. The maximum value of the segment length (Lmax), the minimum value (Lmin), the value at the R wave of the electrocardiogram (LECG R) and that at the end of systole (LES) were calculated. We calculated the total shortening rate as (Lmax--Lmin)/Lmax X 100 and systolic shortening rate as (LECG R--LES)/LECG R X 100. In normal subjects, the total shortening rate was 10.1 +/- 2.7 (SD) at the anterior interventricular septum; 11.8 +/- 3.3 at the interior interventricular septum; and 13.4 +/- 4.5 at the free wall, and 7.9 +/- 4.2% at the atrioventricular groove. Systolic shortening rates in these four areas were 7.2 +/- 2.7, 9.3 +/- 3.7, 9.8 +/- 4.0 and 0.8 +/- 8.1%, respectively, also demonstrating smaller shortening at the anterior interventricular septum than at the free wall. In patients with anteroseptal infarction, total shortening rates were 7.4 +/- 1.9, 7.8 +/- 4.4, 10.4 +/- 3.5 and 8.3 +/- 3.6% respectively, likewise showing decreased shortening at the anterior interventricular septum. In these patients, decreases of systolic shortening rates at the anterior or interior interventricular septum were more marked; namely 4.4 +/- 2.7 and 2.4 +/- 3.6%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)