de Simone G, Ganau A, Roman M J, Devereux R B
Division of Cardiology, New York Hospital-Cornell Medical Center, New York, USA.
J Hypertens. 1997 Sep;15(9):1011-7. doi: 10.1097/00004872-199715090-00012.
To study left ventricular longitudinal shortening in arterial hypertension and the relative contribution of longitudinal and circumferential fiber shortening to ventricular ejection.
Two-dimensional and M-mode echocardiograms were obtained for 50 normotensive subjects (aged 49 +/- 12 years) and 50 never-treated mild hypertensive patients (aged 49 +/- 11 years), to measure the minor-axis endocardial and midwall shortening, long-axis shortening and ejection fraction.
The midwall shortening was lower in hypertensive than it was in normotensive subjects (P < 0.001) and was related inversely to the circumferential wall stress for both groups (P < 0.04 and 0.0001, respectively). The long-axis shortening in hypertensive patients (22.2 +/- 4.2%) and in normotensives (23.6 +/- 5.4%) was not statistically different, and was not related either to the meridional or to the circumferential wall stress. The ejection fraction was also similar for the two groups (68.2 +/- 6.3 versus 68.6 +/- 5.6%). Both for normotensive and for hypertensive subjects, the ejection fraction was influenced mainly by the midwall shortening (61 and 40% of the variance for normal and hypertensive individuals, respectively), with a minor contribution from the long-axis shortening, which was 7% for normotensive subjects and 18% for hypertensive patients, a statistically significant difference (P < 0.001). The combined effect of midwall and longitudinal shortenings on the ejection fraction was regulated by the relative wall thickness, and was maximal for hypertensive patients with an ejection fraction greater than that predicted by the midwall shortening.
Left ventricular ejection is produced principally by circumferential shortening and is related independently to the relative wall thickness. In the presence of arterial hypertension and an altered cardiac load, longitudinal shortening becomes an important mechanism by which to augment ejection, thereby offsetting the reduction in midwall shortening.
研究动脉高血压患者左心室纵向缩短情况以及纵向和圆周纤维缩短对心室射血的相对贡献。
对50名血压正常者（年龄49±12岁）和50名未经治疗的轻度高血压患者（年龄49±11岁）进行二维和M型超声心动图检查，以测量短轴心内膜和心肌中层缩短、长轴缩短及射血分数。
高血压患者的心肌中层缩短低于血压正常者（P<0.001），且两组的心肌中层缩短均与圆周壁应力呈负相关（分别为P<0.04和P<0.0001）。高血压患者（22.2±4.2%）和血压正常者（23.6±5.4%）的长轴缩短无统计学差异，且与经线或圆周壁应力均无关。两组的射血分数也相似（分别为68.2±6.3%和68.6±5.6%）。对于血压正常者和高血压患者，射血分数主要受心肌中层缩短影响（正常人和高血压患者分别占方差的61%和40%），长轴缩短的贡献较小，血压正常者为7%，高血压患者为18%，差异有统计学意义（P<0.001）。心肌中层和纵向缩短对射血分数的联合作用受相对壁厚度调节，对于射血分数大于心肌中层缩短预测值的高血压患者，该联合作用最大。
左心室射血主要由圆周缩短产生，且独立于相对壁厚度。在存在动脉高血压和心脏负荷改变的情况下，纵向缩短成为增加射血的重要机制，从而抵消心肌中层缩短的减少。
