Laskey Warren K, Plappert Theodore A, Sutton Martin G St John
Division of Cardiology, Department of Internal Medicine, University of New Mexico School of Medicine, MSC10-5550, 1 University of New Mexico, Albuquerque, NM 87131, USA.
J Heart Valve Dis. 2007 May;16(3):247-54.
Left ventricular adaptation to chronic volume overload results in dramatic changes in ventricular geometry and hemodynamics. These changes are reflected in alterations in mechanical load and, eventually, contractile function.
The study included 17 patients undergoing clinically driven invasive evaluation for mitral regurgitation (MR). Simultaneous catheter-tip manometry and M-mode echocardiography allowed for derivation of meridional and circumferential wall stress at end-diastole, end-systole, peak systole, and the average over the systolic ejection period. Assessment of contractile function was performed by analysis of: the overall group relationship between baseline end-systolic stress (ESS) and end-systolic dimension (ESD); subject-specific analysis of the relationship between ESS and ESD derived from pharmacologic load alteration; and subject- specific analysis of the relationship between left ventricular minor axis shortening and ESS. The acquired data were compared to data from 10 control subjects who were undergoing invasive evaluation and were free from cardiovascular disease.
Compared to controls, patients with chronic MR (mean regurgitant fraction 57%) were characterized by significantly increased angiographic end-diastolic and end-systolic volumes, lower cardiac indices, and similar left ventricular ejection fractions. Patients with chronic MR were also characterized by increased preload (end-diastolic stress) and afterload (mean systolic stress). ESS was not consistently increased in these patients, despite the increased chamber size. The severity of clinical symptoms was associated with the magnitude of alteration in afterload (mean systolic stress). Using different methodologies, a substantial prevalence of depressed contractile function was identified in those patients with preserved ejection fraction.
When compared to an age- and gender-matched controls, symptomatic patients with MR have similar left ventricular ejection performance in the setting of increased pre-load and after-load. Symptom severity was associated with increased afterload. The prevalence of contractile dysfunction in this setting was substantial.
左心室对慢性容量超负荷的适应性会导致心室几何形状和血流动力学发生显著变化。这些变化反映在机械负荷的改变上，并最终反映在收缩功能的改变上。
本研究纳入了17例因二尖瓣反流（MR）接受临床驱动的有创评估的患者。同步导管尖端测压和M型超声心动图可得出舒张末期、收缩末期、收缩期峰值以及整个收缩射血期的平均子午线壁应力和圆周壁应力。通过分析以下内容来评估收缩功能：基线收缩末期应力（ESS）与收缩末期内径（ESD）之间的总体组间关系；从药物负荷改变得出的ESS与ESD之间关系的个体特异性分析；以及左心室短轴缩短与ESS之间关系的个体特异性分析。将获得的数据与10名接受有创评估且无心血管疾病的对照受试者的数据进行比较。
与对照组相比，慢性MR患者（平均反流分数57%）的特点是血管造影舒张末期和收缩末期容积显著增加、心脏指数较低以及左心室射血分数相似。慢性MR患者还具有前负荷（舒张末期应力）和后负荷（平均收缩期应力）增加的特点。尽管心室大小增加，但这些患者的ESS并未持续增加。临床症状的严重程度与后负荷（平均收缩期应力）的改变幅度相关。使用不同方法，在射血分数保留的患者中发现相当比例的患者存在收缩功能降低。
与年龄和性别匹配的对照组相比，有症状的MR患者在预负荷和后负荷增加的情况下具有相似的左心室射血性能。症状严重程度与后负荷增加相关。在这种情况下，收缩功能障碍的患病率相当高。
