Lamers Luke, Ensing Greg, Pignatelli Ricardo, Goldberg Caren, Bezold Louis, Ayres Nancy, Gajarski Robert
Division of Pediatric Cardiology, C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan, USA.
J Am Coll Cardiol. 2006 Jun 6;47(11):2283-8. doi: 10.1016/j.jacc.2006.03.005. Epub 2006 May 15.
The aim of this work was to evaluate myocardial contractility using the end-systolic wall stress (ESSm)-velocity of circumferential fiber shortening (VCFc) relationship in sickle cell anemia (SCA) patients compared with a similar age group of African-American (AA) control patients.
Abnormalities of myocardial function have been documented in SCA patients using load-dependent echocardiographic indexes. Whether the systolic dysfunction results from impaired myocardial contractility or altered loading conditions is unknown because controlled studies using a load-independent measure of contractility have not been performed.
Fifty healthy AA patients and 57 SCA patients age 3 months to 18 years were studied. Simultaneous indirect arterial pulse tracing, phonocardiogram, electrocardiogram, and M-mode tracing of the left ventricular (LV) short-axis were recorded. The LV dimensions, corrected ejection time (ETc), percent fractional shortening (%FS), VCFc, and ESSm were determined. The ESSm-VCFc relationship was calculated and compared between groups. Duration and severity of anemia and effects of exchange transfusion on the ESSm-VCFc relationship were determined.
The SCA patients had increased LV dimensions in systole and diastole, and increased indexed LV mass. Load-dependent measurements of LV function (ETc, %FS, and VCFc) were lower in SCA patients, and afterload, as measured by ESSm, was increased. The ESSm-VCFc relationship demonstrated reduced contractility in SCA patients compared with control subjects. Degree and duration of anemia along with exchange transfusions did not impact contractility.
Sickle cell anemia patients have significant LV dilatation and increased LV mass due to abnormal loading conditions. Contractility, measured by the ESSm-VCFc index, is lower in SCA patients and was not negatively impacted by severity or duration of anemia, or exchange transfusions. The underlying mechanism explaining these findings requires further investigation.
本研究旨在通过终末收缩期壁应力（ESSm）与圆周纤维缩短速度（VCFc）的关系来评估镰状细胞贫血（SCA）患者的心肌收缩力，并与年龄相仿的非裔美国（AA）对照患者进行比较。
使用依赖负荷的超声心动图指标已证实SCA患者存在心肌功能异常。由于尚未进行使用不依赖负荷的收缩力测量方法的对照研究，因此尚不清楚收缩功能障碍是由心肌收缩力受损还是负荷条件改变所致。
研究了50名年龄在3个月至18岁之间的健康AA患者和57名SCA患者。同时记录间接动脉脉搏描记图、心音图、心电图和左心室（LV）短轴的M型描记图。测定左心室尺寸、校正射血时间（ETc）、缩短分数百分比（%FS）、VCFc和ESSm。计算并比较两组之间的ESSm-VCFc关系。确定贫血的持续时间和严重程度以及换血对ESSm-VCFc关系的影响。
SCA患者在收缩期和舒张期的左心室尺寸增加，左心室质量指数增加。SCA患者左心室功能的依赖负荷测量值（ETc、%FS和VCFc）较低，而用ESSm测量的后负荷增加。与对照组相比，ESSm-VCFc关系显示SCA患者的收缩力降低。贫血的程度和持续时间以及换血均未影响收缩力。
镰状细胞贫血患者由于异常的负荷条件而出现明显的左心室扩张和左心室质量增加。用ESSm-VCFc指数测量的收缩力在SCA患者中较低，并且不受贫血严重程度或持续时间以及换血的负面影响。解释这些发现的潜在机制需要进一步研究。
