| pubmed-article:8013523 | pubmed:abstractText | The effect of coronary insufficiency on the myocardial contraction pattern was studied in 11 thoracotomized cats using apical long axis echocardiograms and cross-oriented segments in the anterior midwall. Myocardial tissue blood flow was studied using radiolabelled microspheres. After circumflex coronary artery occlusion, ejection shortening increased on average 17% for circumferential segments (P < 0.05) and 61% for longitudinal segments (P < 0.001). Hyperkinesis was also validated as augmented anterior endocardial wall motion and wall thickening. Circumflex occlusion increased end-systolic sphericity of the left ventricle (P < 0.05). Subsequent underperfusion of the left coronary artery, in two discrete steps, decreased subendocardial blood flow by, on average, 36% (P < 0.001) and 75% (P < 0.001) vs the post-occlusion value, while subepicardial flow did not change. While subendocardial blood flow decreased by 36%, systolic shortening of the global major axis decreased, by, on average, 77% (P < 0.001), shortening of the longitudinal segments by 36% (P < 0.001), and systolic shortening of the minor axis by 18% (P < 0.05), whereas shortening of midwall circumferential segments did not change. This study shows that changes in myocardial contraction in both non-ischaemic and ischaemic regions during coronary insufficiency are most pronounced in the direction of the cardiac major axis. | lld:pubmed |
