St John Sutton M G, Plappert T A, Hirshfeld J W, Reichek N
Circulation. 1984 Feb;69(2):259-68. doi: 10.1161/01.cir.69.2.259.
We describe a noninvasive method for determining end-systolic meridional and circumferential wall stress and left ventricular architecture as the ratio of muscle to cavity area. With this technique, which uses two-dimensional echocardiography and cuff-determined values for systolic blood pressure, we assessed wall stress and left ventricular architecture in 15 normal subjects and 15 asymptomatic patients with severe chronic aortic regurgitation at rest and after load manipulations with sublingual nitroglycerin. Resting end-systolic meridional and circumferential stress were increased in patients with aortic regurgitation (113.9 +/- 29 and 260 +/- 50.7 X 10(3) dynes/cm2) compared with those in normal subjects (85.6 +/- 15.4 and 214.1 +/- 28.4 X 10(3) dynes/cm2) (both p less than .01) and remained significantly greater after nitroglycerin. Meridional stress values obtained from two-dimensional echocardiographic studies correlated closely (r = .89) with values calculated from simultaneously recorded M mode echocardiograms. Ejection fraction in patients with aortic regurgitation and normal subjects were similar at rest (55 +/- 10% vs 59 +/- 6%) and were unchanged by nitroglycerin. In spite of the increased left ventricular mass in patients with aortic regurgitation (227 +/- 60 g vs 130 +/- 22 g in normal subjects), the mass-to-volume ratio and the ratio of muscle to cavity area in diastole in patients with aortic regurgitation were significantly lower than normal (0.90 +/- 0.23 vs 1.30 +/- 0.21 and 0.91 +/- 0.23 vs 1.11 +/- 0.18 [p less than .005 and p less than .02]). These differences were exaggerated after nitroglycerin, while concomitant changes in relative wall thickness were virtually undetected by M mode echocardiography. Thus this technique can be used for early recognition of afterload excess and changes in left ventricular architecture in patients with aortic regurgitation. Furthermore, the mean slopes of the circumferential stress-diameter and meridional stress-length lines, which represent load-independent indexes of myocardial contractile state, could be assessed and were similar in the group of patients with asymptomatic aortic regurgitation and normal subjects, indicating that overall myocardial contractility was still normal. We conclude that circumferential and meridional wall stress, myocardial contractility, and left ventricular architecture can be determined noninvasively. These measurements may prove to be useful in assessing patients with primary myocardial or valvular heart disease and determining their long-term management.
我们描述了一种非侵入性方法，用于确定收缩末期经线和圆周壁应力以及左心室结构，即肌肉与腔面积之比。通过这项技术，利用二维超声心动图和袖带测定的收缩压值，我们在15名正常受试者和15名无症状的严重慢性主动脉瓣反流患者休息时以及舌下含服硝酸甘油进行负荷操作后，评估了壁应力和左心室结构。与正常受试者（85.6±15.4和214.1±28.4×10³达因/cm²）相比，主动脉瓣反流患者的静息收缩末期经线和圆周应力增加（113.9±29和260±50.7×10³达因/cm²）（两者p均小于0.01），硝酸甘油给药后仍显著更高。二维超声心动图研究获得的经线应力值与同时记录的M型超声心动图计算值密切相关（r = 0.89）。主动脉瓣反流患者和正常受试者的静息射血分数相似（55±10%对59±6%），且硝酸甘油给药后无变化。尽管主动脉瓣反流患者的左心室质量增加（227±60 g对正常受试者的130±22 g），但主动脉瓣反流患者舒张期的质量与容积比以及肌肉与腔面积比显著低于正常（0.90±0.23对1.30±0.21以及0.91±0.23对1.11±0.18 [p小于0.005和p小于0.02]）。硝酸甘油给药后这些差异更加明显，而M型超声心动图几乎未检测到相对壁厚度的伴随变化。因此，这项技术可用于早期识别主动脉瓣反流患者的后负荷过重和左心室结构变化。此外，可以评估代表心肌收缩状态的负荷无关指标的圆周应力 - 直径和经线应力 - 长度线的平均斜率，并且在无症状主动脉瓣反流患者组和正常受试者中相似，表明整体心肌收缩力仍正常。我们得出结论，圆周和经线壁应力、心肌收缩力以及左心室结构可以通过非侵入性方法确定。这些测量可能被证明对评估原发性心肌或瓣膜性心脏病患者以及确定他们的长期治疗有用。
