Hexeberg E, Birkeland S, Grong K, Matre K, Lekven J
Department of Surgery, University of Bergen, Haukeland Hospital, Norway.
Eur Heart J. 1992 Jul;13(7):981-9. doi: 10.1093/oxfordjournals.eurheartj.a060304.
The effect of coronary stenosis on the uniformity of local left ventricular contraction was studied in 11 open-chest cats. Coronary artery stenosis was established by controlled constriction of a shunt line from the right subclavian artery to the left main coronary artery. Two pairs of ultrasonic crystals were placed in the midwall of the anterior left ventricular wall; one pair, circumferential (Circ), aligned with midwall and subepicardial fibres; the other, longitudinal (Long), aligned with subendocardial fibres. Three steps of coronary perfusion pressure (poststenotic) were studied; open shunt line (140 +/- 4 mmHg), light stenosis (94 +/- 2 mmHg), and severe stenosis (70 +/- 3 mmHg). Subendocardial tissue blood flow showed the most pronounced reduction (from 1.87 +/- 0.11 to 1.43 +/- 0.10 and 0.86 +/- 0.12 ml min-1 g-1, respectively) with coronary stenosis whereas subepicardial flow remained unchanged. Maximal systolic shortening deteriorated for both segments. However, it was most pronounced for longitudinal segments. Duration of shortening decreased in longitudinal segments during severe stenosis to 62% of duration with open shunt (P less than 0.05), but was unchanged in circumferential segments. Long/Circ ratio of maximal systolic shortening declined by 50% (P less than 0.05) with reduction of coronary perfusion pressure. The reduced uniformity of segment shortening, caused by a marked reduction of longitudinal segment shortening, may support the notion that the longitudinal segment reflects performance of subendocardial fibres. This study demonstrates local non-uniformity of two-dimensional deformation during coronary artery stenosis and subendocardial hypoperfusion.
在11只开胸猫身上研究了冠状动脉狭窄对局部左心室收缩均匀性的影响。通过控制从右锁骨下动脉到左主冠状动脉的分流线的收缩来建立冠状动脉狭窄。将两对超声晶体置于左心室前壁的中层壁；一对为圆周方向（Circ），与中层壁和心外膜下纤维对齐；另一对为纵向方向（Long），与心内膜下纤维对齐。研究了三个冠状动脉灌注压（狭窄后）步骤；开放分流线（140±4 mmHg）、轻度狭窄（94±2 mmHg）和重度狭窄（70±3 mmHg）。随着冠状动脉狭窄，心内膜下组织血流显示出最明显的减少（分别从1.87±0.11降至1.43±0.10和0.86±0.12 ml min-1 g-1），而心外膜血流保持不变。两个节段的最大收缩期缩短均恶化。然而，纵向节段最为明显。在重度狭窄期间，纵向节段的缩短持续时间降至开放分流时的62%（P<0.05），而圆周节段则保持不变。随着冠状动脉灌注压降低，最大收缩期缩短的Long/Circ比值下降了50%（P<0.05）。纵向节段缩短的显著减少导致节段缩短均匀性降低，这可能支持纵向节段反映心内膜下纤维性能的观点。本研究证明了冠状动脉狭窄和心内膜下灌注不足期间二维变形的局部不均匀性。
