Yano M, Kohno M, Konishi M, Obayashi M, Kobayashi S, Seki K, Lee B, Matsuzaki M
Second Department of Internal Medicine, Yamaguchi University School of Medicine, Japan.
Basic Res Cardiol. 1997 Apr;92(2):115-22. doi: 10.1007/BF00805572.
The aim was to examine the influence of the independent increase of aortic wall characteristics from vascular resistance on global left ventricular (LV) function in intact hearts. In 11 anesthetized dogs, aortic stiffness was increased by a constriction of the thoracic aorta using a stiff tube, and then, in nine dogs, total systemic resistance (TSR) was increased by an infusion of angiotensin II. During the above procedures, aortic input impedance and LV dimension were measured. Aortic input impedance spectra revealed the steady increase in the moduli at high frequencies by aortic constriction, indicating the increase in aortic stiffness. At the stage of increased aortic characteristic impedance (Zc) (134% of control) without a change in TSR, both LV end-diastolic diameter (LVEDD, 99%, p < 0.01 and stroke volume (SV, 95%, p < 0.01) decreased significantly without a change in LV end-systolic diameter (LVESD). During the increase in TSR produced by angiotensin II (128% of control) without a change in Zc, LVEDD tended to increase and LVESD significantly increased (103%, p < 0.01) associated with a decrease in SV (94%, p < 0.01). LV systolic mean wall stress was increased by angiotensin II (118%, p < 0.01), whereas it was unchanged by aortic constriction. In conclusion, the isolated increase in aortic stiffness without a change in TSR was associated with a reduction in LV preload and SV.
目的是研究在完整心脏中，血管阻力导致的主动脉壁特性独立增加对整体左心室（LV）功能的影响。在11只麻醉犬中，使用硬管对胸主动脉进行缩窄以增加主动脉僵硬度，然后在9只犬中，通过输注血管紧张素II增加总全身阻力（TSR）。在上述过程中，测量主动脉输入阻抗和左心室尺寸。主动脉输入阻抗谱显示，主动脉缩窄使高频模量稳步增加，表明主动脉僵硬度增加。在主动脉特征阻抗（Zc）增加至对照的134%且TSR无变化的阶段，左心室舒张末期直径（LVEDD，为对照的99%，p<0.01）和每搏输出量（SV，为对照的95%，p<0.01）均显著降低，而左心室收缩末期直径（LVESD）无变化。在血管紧张素II使TSR增加至对照的128%且Zc无变化的过程中，LVEDD有增加趋势，LVESD显著增加（为对照的103%，p<0.01），同时SV降低（为对照的94%，p<0.01）。血管紧张素II使左心室收缩期平均壁应力增加（为对照的118%，p<0.01），而主动脉缩窄对其无影响。总之，在TSR无变化的情况下，单纯主动脉僵硬度增加与左心室前负荷和SV降低有关。
