Early involutionary vectorcardiographic signs of right ventricular hypertrophy

QRS loop areas in selective right ventricular overload: relation to hemodynamic status

The utility of vectorcardiographic relative QRS loop area criteria in identifying significant hemodynamic abnormality (a mean pulmonary artery pressure greater than 25 mmHg and/or a pulmonary to systemic flow ratio greater than 1.5) in patients with cardiac lesions associated with selective right ventricular overload was investigated in a consecutive series of patients, 291 with Heart Disease and 135 Controls. The specificity and predictive value of individual abnormally increased right quadrant areas were greater than 90% and greater than 80%, respectively. The predictive value of an isolated increase in left anterior area greater than 70% in identifying the absence of significant hemodynamic abnormality (= 91%) was similar to a negative VCG (= 80%). False positive increases in right quadrant areas were found only in association with counterclockwise transverse plane QRS loop rotation. The predictive value of a counterclockwise loop rose from 77% to 86% by increasing the diagnostic requirement for an abnormal increase in right inferior and posterior area from 20%, respectively, to 26%, respectively.

Changes in heart dipole moment after surgical correction of atrial septal defect

Spatial dipole moment of the heart (M) was measured in patients before and 1 to 2 weeks after repair of atrial septal defect. In normals three peaks of M were found, corresponding to excitation of the septum (M1), ventricular walls (M2), and basal portion of ventricles (M3). Most of the patients also had an M2a peak at 52 to 56 per cent of QRS duration. The patients with secundum defects were divided into two groups, A and B, depending on whether right ventricular pressure was less than or greater than 30 mm. Hg. M1 was smaller for the Group B patients than for the normals for Group A and decreased slightly after surgery. M2 was about half normal for Group A and one third normal for Group B. After surgery M2 increased for both Groups but was still below normal. There were small mean clockwise rotations of the M2 vector in the horizontal plane PO. The M2a vector pointed to the right anterior or posterior and generally downward. In three Group A patients the M2a peak disappeared PO but in two others it increased in magnitude with a counterclockwise rotation in the horizontal plane. In the Group B patients, M2a increased in all cases. The M3 vectors generally increased slightly in magnitude postoperatively. M3 pointed posteriorly in the normals but to the right in the patients, with little change in direction after surgery. Both P and T curves dropped in magnitude after surgery. The changes observed may be due in part to restoration of right ventricular blood volume towards normal after surgery. The remaining VCG abnormalities should be due to right ventricular hypertrophy.

Advances in clinical vectorcardiography

With use of the Frank lead system, still loop and timed vectorcardiograms were recorded in more than 5,000 patients sujected to complete right and left hear catheterization and selective coronary cine angiography. Data so obtianed demonstrated clincila superiority of the vectorcardiogram over the standard 12 lead scalar electrocardiogram. Specific advantages of the vectorcardiogram include (1) recognititin of undetected atrial and ventrcular hypertropy, (2) greater sensitivity in identification of myocardial infaraction, and (3) superior capability for diagnosis of multiple infaractions in the presnece of fascicular and burnany number of simultaneously recoreded electrocardiographic leadsfor the analysis of complex arrhythmias and beat to beat changes in intraventricula conduction. SINCE THE VALIDITY AND USEFULNESS OF THIS TECHNIQUE HAVE BEEN ESTABLISHED, IT SHOULD BECOME PART OF THE ROUTINE NONINVASIVE EVALUATION OF PATIENTS WITH CARDIOVASCULAR DISORDERS.