Clinical Application Value Of 12-lead Vectorcardiogram In Acute Inferior Myocardial Infarction

Objective: To study the characteristics of 12-lead vectorcardiogram in acute inferior myocardial infarction(AIMI),and to explore the value of 12-lead vectorcardiogram in infarct-related artery(IRA)in patients with AIMI.Methods: A retrospective analysis of 90 patients in our hospital from January 2016 to August 2021 which underwent coronary angiography(CAG)and relevant examinations were clinically diagnosed with AIMI.By using the ECG Workstation V.3.4.2 software system of Kangtai Medical Company Limited,the electrocardiogram of all patients was converted into vectorcardiogram,and the direction of rotation of QRS loop and T loop were obtained,0.01-0.04 s QRS vector amplitude and angle,the maximal QRS vector amplitude and angle,the maximal T vector amplitude and angle,The angle between maximal QRS vector and maximal T vector(QRS-T angle),ST vector amplitude and angle,etc...Observe the changes of parameters of 12-lead vectorcardiogram of AIMI patients,analyze the diagnosis standards for 12-lead vectorcardiogram of AIMI.Then according to the Gensini score and IRA to groups the AIMI patients.and to explore whether parameters of 12-lead vectorcardiogramm are helpful judgment the degree and location of coronary artery of AIMI patients,laying a foundation for the promotion and application of 12-lead vectorcardiogramm in the future.Results: 1.The initial vector of QRS and QRS loop in the frontal plane were inscribed in clockwise(CW)direction in most AIMI patients,and the T loop were inscribed in Counterclockwise(CCW)direction.In some patients,the QRS loop and T loop in the sagittal plane were inscribed in CCW or "8" direction,and T loop in horizontal plane were inscribed in CW direction.In the control group,the initial vector of QRS and QRS loop in the frontal plane were inscribed in Counterclockwise(CCW)direction,and the T loop were inscribed in clockwise(CW).The sagittal initial QRS vector,QRS loop and T loop do not inscribed in Counterclockwise(CCW)direction,but in horizontal plane T loop inscribed in Counterclockwise(CCW)direction.2.In patients with AIMI,the 0.01s-0.04 s QRS vector was displaced to the left,anterior,and superior;the ST vector amplitude increased in all planes,and the ST vector pointed inferiorly and displaced to the right-posteriorly;the maximal QRS vector amplitude decreased in the frontal plane,displaced to the left,superior,and anterior;the maximal T vector was displaced to the right,superior,and posterior;and the QRS-T angle increased in the frontal plane.3.When AIMI combined with ST segment depression in other leads,the QRS vector angle at 0.03 s and 0.04 s in frontal planes,the QRS vector angle at 0.03 s in sagittal plane,the ST vector amplitude and direction,and the maximal T vector direction changes more obviously.4.If the LCX arterial lesions,the maximal QRS vector and ST vector both point to the anterior and left,If the RCA arterial lesions,the ST vector points to the posterior and right,and the maximal QRS vector point to the left and posterior,and is more deviated to the left,(at 23±40°in the frontal plane,at-16±60°in horizontal plane);IF the multi-artery lesions are possible,the ST vector points to the posterior and right,the maximal QRS vector point to the left and posterior,and is more deviated to the posterior(at 47±46°in the frontal plane,at--5±42°in horizontal plane).5.Only a few parameters were different between the Gensini score ≤ 32 group and the Gensini score > 50 group,the 12-lead vectorcardiography was not significant for judging the degree of coronary artery disease.6.After Logistics regression analysis and ROC curve analysis,The best diagnostic limits of ROC curve analysis were as follows: in frontal plane,the 0.02 s QRS vector amplitude>85μV,the 0.04 s QRS vector amplitude<615μV,the 0.01 s QRS vector angle<-6°,the 0.02 s QRS vector angle<-4°,the 0.03 s QRS vector angle<10°,the ST vector amplitude>43μV,the ST vector angle>87°,the QRS maximal vector amplitude<615μV,the maximal QRS vector angle in frontal plane<4°,the QRS-T angle>35°.Conclusions:1.The typical changes of 12-lead vectorcardiogram in AIMI patients include:(1)in frontal plane,the initial QRS vector is inscribed by CW direction;(2)The QRS loop shifted to the upper and to the left,and the early superior forces were 0.02 s or more in duration;(3)the ST vector amplitude were increased,and points downward,deviated to the right-posteriorly,and the ST vector amplitude > 43 μV in frontal plane;(4)the maximal QRS vector is displaced to the left,anterior and superior in frontal plane,and the maximal QRS vector angle < + 4°in frontal plane.2.If the maximal QRS vector and ST vector both point to the anterior and left,it suggests that LCX arterial lesions.If the ST vector points to the posterior and right,and the maximal QRS vector point to the left and posterior,and is more deviated to the left,it suggesting that RCA arterial lesions;If the ST vector points to the posterior and right,the maximal QRS vector point to the left and posterior,and is more deviated to the posterior,it suggesting that multi-artery lesions are possible.