Li Zhimin, Strasburger Janette F, Cuneo Bettina F, Gotteiner Nina L, Wakai Ronald T
Department of Medical Physics, University of Wisconsin-Madison, Madison, Wis, USA.
Circulation. 2004 Oct 12;110(15):2097-101. doi: 10.1161/01.CIR.0000144302.30928.AA. Epub 2004 Oct 4.
Cardiogram signal amplitude is a key index of hypertrophy but has not been investigated extensively in utero. In this study, magnetocardiography was used to assess P and QRS amplitude in normal subjects and subjects with fetal arrhythmia.
The study cohort consisted of 68 normal fetuses and 25 with various arrhythmias: 9 reentrant supraventricular tachycardia (SVT), 2 ventricular tachycardia (VT), 2 sinus tachycardia, 2 blocked atrial bigeminy, 2 congenital second-degree atrioventricular (AV) block, and 8 congenital complete AV block. Subjects with congenital AV block, all presenting with bradycardia, showed large QRS amplitude, exceedingly large P-wave amplitude, and long P-wave duration. The 2 subjects with VT, both with poor ventricular function, also exhibited large P waves. SVT was associated with only moderate signal amplitude elevation.
The data imply that AV block in utero is accompanied by hypertrophy, which is more pronounced for the atria than the ventricles. We hypothesize that the hypertrophy results from a compensatory response associated with regulation of cardiac output and is likely to be observable in other arrhythmias and disease states. Magnetocardiography may be more sensitive than fetal echocardiography for detection of atrial hypertrophy in utero.
心电图信号幅度是肥厚的关键指标，但尚未在子宫内进行广泛研究。在本研究中，使用磁心动图评估正常受试者和胎儿心律失常受试者的P波和QRS波幅度。
研究队列包括68例正常胎儿和25例患有各种心律失常的胎儿：9例折返性室上性心动过速（SVT）、2例室性心动过速（VT）、2例窦性心动过速、2例阻滞性房性二联律、2例先天性二度房室（AV）阻滞和8例先天性完全性AV阻滞。患有先天性AV阻滞的受试者均表现为心动过缓，QRS波幅度大，P波幅度极大，P波持续时间长。2例VT受试者，心室功能均较差，P波也较大。SVT仅与信号幅度中度升高有关。
数据表明子宫内AV阻滞伴有肥厚，心房比心室更明显。我们假设肥厚是由与心输出量调节相关的代偿反应引起的，并且可能在其他心律失常和疾病状态中观察到。磁心动图在检测子宫内心房肥厚方面可能比胎儿超声心动图更敏感。
