The Influence of Reverse Connection of Limb Lead Electrodes on the Left and Right Upper Limbs in Electrocardiogram on Diagnosis

GAO Xiumei; LI Qiang; XU Zhaolong; YANG Wenqi; CHANG Qinghua; ZHANG Mengyao; LIU Renguang

doi:10.3969/j.issn.2096-305X.2025.03.014

Abstract：Objective To strengthen the importance of standardized electrode connections in electrocardiogram examination and the impact of misconnections on electrocardiogram diagnosis.Methods 20 doctors,nurses and students with normal electrocardiogram during physical examination were selected.(1)According to the standardized connection of the electrocardiogram,a routine 12-lead electrocardiogram were connected and recorded to analyze P-QRS-STT;(2)the electrodes of left and right limbs were reversed to record a 12-lead electrocardiogram to compare and analyze the changes of P-QRS-STT.Results(1)The standardized connection of 12-lead electrocardiograms show sinus rhythm,and P-QRS-STT were within the normal range;(2)there is no change in the chest lead electrocardiogram when the electrodes of the left and right upper limbs were reversed.Except for lead aVF,all limb leads showed significant changes resembling mirror-image dextrocardia.P wave indicates left atrial rhythm/atrial inversion;QRS axis significantly deviates to the right,and lead aVR′(R/S>1)indicates right ventricular hypertrophy;there is left posterior branch block;aVL′and I′exhibit abnormal Q wave,resembling high lateral wall myocardial infarction;the T waves were negative in leads Ⅰ′,Ⅱ′ and aVL′,resembling abnormal repolarization.Conclusion The standardized connection in electrocardiogram examination is a prerequisite for the correct diagnosis of electrocardiogram;misconnection can change the direction of the axis and the corresponding position with the heart,affecting electrocardiogram diagnosis.Reverse connection of the left and right limbs can cause abnormal changes in the P-QRS-STT,resembling a mirror-image dextrocardia.