Vectorcardiographic criteria of high posterior infarction: differentiation from normal subjects, right ventricular hypertrophy and primary myocardial disease.

In order to differentiate the vectorcardiogram (VCG) in high posterior infarction (HPI) from VCGs of normal subjects, right ventricular hypertrophy (RVH) and primary myocardial disease (PMD), the following criteria were presented; cases satisfying the criteria could be diagnosed as high posterior infarction. In cases with posterior component/anterior component (P/L) less than 1.0 (Group A); (1)--45 degrees vector/ab less than or equal to 0.25, (2) the maximal T vector in the horizontal plane greater than or equal to + 20 degrees, (3) I (inferior component)/L (left component) less than 1.0 and (4) no anterior convexity of the afferent limb of the left sagittal QRS loop. In cases with P/A greater than or equal to 1.0 (Group B);--45 degrees vector/ab less than or equal to 0.2, (2) the maximal T vector in the horizontal plane greater than or equal to + 20 degrees, (3) I/L less than 1.0 and (4) no anterior convexity of the affernt limb of the left sagittal QRS loop. Only one false negative case in HPI was found and only seven false positive cases in normal subjects, RVH and PMD. A correct diagnosis can be made with 97.4% accuracy. These criteria for differentiation were tested by reexamining the cases with selective coronary arteriography. Five cases satisfied the criteria of this method. Complete obstruction of the circumflex coronary artery was found in four of these cases, and severe stenosis (greater than or equal to 90%) in one case. Akinesis or hypokinesis of the posterobasal segment in the left ventricle was also observed in all five cases.