Fitchett D H, Simkus G, Genest J, Marpole D, Beaudry P
Division of Cardiology, Royal Victoria Hospital, Montreal, Quebec.
Can J Cardiol. 1988 Mar;4(2):72-5.
It has previously been shown that nitroglycerin increases the compliance of forearm arteries. The present study investigates whether nitroglycerin reduces the hydraulic load on the heart (as measured by aortic input impedance) by a mechanism compatible with an increase in peripheral arterial compliance. In eight subjects, measurements of aortic flow and pressure were made with a catheter tipped probe before and during intravenous nitroglycerin (6 to 30 micrograms/min) administration. The reduction of aortic systolic pressure (129 +/- 5 to 113 +/- 4 mmHg, P less than 0.001) was due to a decrease in the late systolic pressure peak. There was no change in stroke volume, heart rate or systemic vascular resistance. The lower systolic pressure resulted from a decrease in the amplitude of the first harmonic of input impedance (210 +/- 19 to 143 +/- 11 dyne.s.cm-5, P less than 0.005) yet characteristic impedance (a measure of local aortic distensibility) did not change. The ratio of maxima to minima of the impedance spectrum was reduced (1.02 +/- 0.09 to 0.71 +/- 0.11, P less than 0.05) suggesting a decrease in the amplitude of reflected waves contributing to aortic impedance. Nitroglycerin at doses which have no effect on arteriolar resistance vessels, reduces systolic aortic pressure by diminishing the amplitude of wave reflections returning to the ascending aorta in late systole. This mechanism is compatible with the peripheral arterial effects of nitroglycerin.
先前的研究表明，硝酸甘油可增加前臂动脉的顺应性。本研究旨在探讨硝酸甘油是否通过一种与外周动脉顺应性增加相一致的机制来降低心脏的液压负荷（通过主动脉输入阻抗来衡量）。在8名受试者中，在静脉注射硝酸甘油（6至30微克/分钟）之前和期间，使用导管尖端探头测量主动脉血流和压力。主动脉收缩压的降低（从129±5 mmHg降至113±4 mmHg，P<0.001）是由于收缩期末期压力峰值的降低。每搏输出量、心率或全身血管阻力均无变化。较低的收缩压是由于输入阻抗基波振幅的降低（从210±19达因·秒·厘米⁻⁵降至143±11达因·秒·厘米⁻⁵，P<0.005），而特性阻抗（一种衡量主动脉局部扩张性的指标）没有变化。阻抗谱的最大值与最小值之比降低（从1.02±0.09降至0.71±0.11，P<0.05），表明对主动脉阻抗有贡献的反射波振幅降低。在对小动脉阻力血管无影响的剂量下，硝酸甘油通过减小收缩期末期返回升主动脉的波反射振幅来降低主动脉收缩压。这种机制与硝酸甘油的外周动脉效应相一致。
