左束支阻滞时急性心肌梗死的诊断

Diagnosis of acute myocardial infarction in the presence of left bundle branch block

左束支阻滞(left bundle branch block,LBBB)时心室激动顺序发生改变,左室除极位于QRS波后半部,因此,当LBBB合并急性心肌梗死(acute myocardial infarction,AMI)时,可干扰心电图诊断。本文介绍了Sgarbossa、Smith和巴塞罗那诊断标准,并比较其诊断敏感性及特异性。1996年提出的Sgarbossa标准根据ST段同向改变及过度反向抬高等指标诊断LBBB合并AMI,特异性高,但敏感性低。Smith标准将Sgarbossa标准中的"过度反向抬高≥0.5 m V"修订为考量ST段反向偏移幅度与S(R)波的比值,提高了诊断的敏感性。巴塞罗那标准提出,LBBB时任意导联ST段同向偏移≥0.1 m V,或低电压导联反向偏移≥0.1 m V时,即可诊断AMI,显著提高了诊断敏感性及特异性。Cabrera及Chapman征对LBBB合并AMI也具有辅助诊断价值。

Left bundle branch block(LBBB)results in left ventricular depolarization appearing in the latter half of QRS complex due to altered ventricular activation sequence.Therefore,it could be challenging to make electrocardiographic diagnosis of acute myocardial infarction(AMI)in the presence of LBBB.This paper introduces Sgarbossa’s rule,Smith’s criteria and Barcelona diagnostic criteria,and compares their diagnostic sensitivity and specificity.According to the Sgarbossa’s rule proposed in 1996,LBBB complicating AMI can be diagnosed based on concordant ST alteration,excessive reverse elevation of ST segment and other indexes with high specificity and low sensitivity.Smith’s criteria replaced"excessive discordant ST elevation≥0.5 m V"in Sgarbossa’s rule with ST/S or ST/R ratio,which improves diagnostic sensitivity.The Barcelona criteria propose that in the presence of LBBB,AMI can be diagnosed based on the ECG features,including concordant ST deviation≥0.1 m V in any lead or discordant ST deviation≥0.1 m V in low-voltage lead.The criteria significantly elevate the diagnostic sensitivity and specificity.Cabrera’s sign and Chapman’s sign also play auxiliary roles in diagnosing concomitant AMI and LBBB.