Goldberg A H, Diedericks J, Hopwood M B, Foëx P
Nuffield Department of Anaesthetics, Radcliffe Infirmary, University of Oxford, England.
J Cardiothorac Vasc Anesth. 1992 Oct;6(5):593-9. doi: 10.1016/1053-0770(92)90103-e.
This study was designed to determine whether the end-systolic pressure-length relationship (ESPLR) reflects changes in regional contractility during the imposition of graded ischemia, and whether it is modified by diltiazem during propofol anesthesia. Seven beagles were anesthetized and instrumented to measure left ventricular pressure and subendocardial segment lengths (sonomicrometry) in the region of the left anterior descending (LAD) and circumflex (LC) arteries. Afterload was increased by the tightening of a snare around the descending thoracic aorta. Pressure-length loops were constructed and the slope of the ESPLR and the x-axis intercept, Lo, were calculated. Graded ischemia of the apical myocardium only was accomplished by the tightening of a micrometer-controlled snare around the LAD to produce Critical Constriction (CC), Ischemia 1 and 2 (I1, I2), and Total Occlusion (TO). In the basal LC region, LAD ischemia had no effect on either the ESPLR slope or Lo. In contrast, the ESPLR slope in the LAD area was decreased by ischemia at I1 (-40%), increased at TO (+69%), and unchanged at CC and I2, and was reduced by diltiazem at CC and I2 (-31% and -36%, respectively). The LAD ESPLR Lo was increased by ischemia by 64% and 61% at I2, and 91% and 122% at TO, before and after diltiazem, respectively. In the LC region, diltiazem decreased systolic shortening and the ESPLR slope. These results indicate that diltiazem has negative inotropic properties in both ischemic and nonischemic areas. Also, Lo is not a constant and must always be redetermined for every intervention. In the absence of ischemia, the ESPLR may be a reliable measure of myocardial contractility.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究旨在确定收缩末期压力-长度关系（ESPLR）是否反映了分级缺血过程中局部心肌收缩性的变化，以及在丙泊酚麻醉期间地尔硫䓬是否会对其产生影响。七只比格犬接受麻醉并安装仪器，以测量左前降支（LAD）和左旋支（LC）动脉区域的左心室压力和心内膜下节段长度（超声微测法）。通过收紧围绕胸降主动脉的圈套器来增加后负荷。构建压力-长度环，并计算ESPLR的斜率和x轴截距Lo。仅通过收紧围绕LAD的微米控制圈套器来实现心尖心肌的分级缺血，以产生临界狭窄（CC）、缺血1和2（I1、I2）以及完全闭塞（TO）。在基础LC区域，LAD缺血对ESPLR斜率或Lo均无影响。相比之下，LAD区域的ESPLR斜率在I1时因缺血而降低（-40%），在TO时升高（+69%），在CC和I2时不变，并且在CC和I2时因地尔硫䓬而降低（分别为-31%和-36%）。LAD的ESPLR Lo在I2时因缺血分别增加64%和61%，在TO时分别增加91%和122%，分别在地尔硫䓬给药前后。在LC区域，地尔硫䓬降低了收缩期缩短和ESPLR斜率。这些结果表明，地尔硫䓬在缺血和非缺血区域均具有负性肌力作用。此外，Lo不是一个常数，每次干预时都必须重新确定。在无缺血的情况下，ESPLR可能是心肌收缩性的可靠指标。（摘要截断于250字）
