Use of the vectorcardiogram to recognize right ventricular hypertrophy in mitral stenosis. Correlation with hemodynamic data

Identification of electrocardiographic criteria for diagnosis of right ventricular hypertrophy due to mitral stenosis

Current electrocardiographic (ECG) criteria for diagnosing right ventricular hypertrophy (RVH) have low sensitivity. In this study maximally specific and sensitive ECG criteria for RVH due to mitral stenosis (MS) were developed that incorporated the principles derived from spatial changes in the QRS complex observed on the vectorcardiogram and any existent ECG criteria that supplement the diagnostic capability of the criteria derived from the vectorcardiogram. The standard 12-lead electrocardiograms of a control group of 500 consecutively selected subjects with 50 women and 50 men in each decade between ages 20 and 69 years were compared with the electrocardiograms of a study population of 50 patients with RVH due to MS. Inclusion criteria were a diagnosis of MS by catheterization, normal coronary arteriographic and left ventriculographic findings and no other valvular abnormalities. It was hypothesized that patients with RVH resulting from MS would have QRS forces that are maximally anterior (A) and rightward (R) and minimally posterolateral (PL); thus, the A + R - PL value in the study group would be greater than that in the control group. The subsequently derived formula criterion (A + R - PL greater than or equal to 0.7 mV) and 2 additional criteria, R less than or equal to 0.2 mV in lead I and P less than 0.25 mV in leads II, III, aVF, V1 or V2, were tested in both groups. The specificity and sensitivity of each individual criterion was determined; when combined, the criteria yielded 94% specificity and 64% sensitivity. Moderate to severe RVH due to MS was detected in two-thirds of the patients using the proposed criteria.

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.

Vectorcardiographic and hemodynamic correlation in chronic obstructive pulmonary disease

Vectorcardiograms in 34 patients with chronic obstructive pulmonary disease and 30 normal people were analyzed with the aim of developing sensitive criteria for the detection of pulmonary artery hypertension. The pulmonary artery pressure was correlated with the known vectorcardiographic measurements of the area of the QRS loop and with two new linear measurements which reflect the QRS loop displacement of the right ventricular hypertrophy. The proposed linear vector-cardiographic and the QRS loop area criteria provided a sensitive means for the noninvasive approximate estimation of mean pulmonary artery pressure in patients with chronic obstructive pulmonary disease. Their sensitivity and specificity were proved to be considerable.

New vectorcardiographic criteria for diagnosing right ventricular hypertrophy in mitral stenosis: comparison with electrocardiographic criteria

Frank-lead vectorcardiograms (VCGs) and standard 12-lead electrocardiograms (ECGs) were analyzed to develop simple, linear, quantitative criteria for the diagnosis of right ventricular hypertrophy (RVH). The study subjects included a population with a definite RVH (84 patients with mitral stenosis proved by cardiac catheterization and pulmonary arterial systolic pressure > 40 mm Hg) and a population with minimal likelihood of RVH (173 young, healthy volunteers and 151 normal subjects proved by cardiac catheterization). VCGs were evaluated to identify criteria that provided maximum sensitivity and at least a 95% specificity: the maximum QRS magnitude had to be < 1.8 mV and either (1) the amplitude at -45 degrees (transverse plane) had to be < 0.3 mV or (2) the maximum anterior amplitude plus the maximum rightward amplitude minus the amplitude at -45 degrees must be greater than or equal to 0.5 mV. Application of these criteria achieved 60% (50 of 84) sensitivity in patients with RVH, similar to that for previous VCG criteria but significantly better (p < 0.01) than the best sensitivity with any ECG criteria (27%, 23 of 84). The specificity of the proposed criteria was 96% (310 of 324), significantly better (p < 0.001) than the 78% specificity (252 of 324) of existing VCG criteria. Thus, linear measurements of the QRS complex displayed on the VCG identify 60% of patients with moderate-to-severe RVH and falsely indicate RVH in only 4% of normal subjects.

Computer analysis of the orthogonal electrocardiogram and vectorcardiogram mitral stenosis

Orthogonal electrocardiograms (Frank lead system) from 191 patients with pure mitral stenosis (MS) were compared to electrocardiograms from 510 normal patients and 296 patients with pulmonary emphysema (PE). All patients with MS underwent right heart catheterization; 121 patients underwent both left and right heart catheterization. Three hundred and thirty electrocardiographic measurements were obtained from each record and tested for their ability to distinguish mitral stenosis from normal. Two sets of diagnostic discriminators were selected: (1) ECG measurements which can be easily obtained by hand and (2) measurements which performed best in multivariate analysis using linear discriminant functions. The patients with mitral stenosis were separated into three hemodynamic subgroups according to mean pulmonary artery pressure (PAP) (0-30, 31-40, and > 40 mm Hg). The ability of the selected measurements to recognize mitral stenosis increased as mean pulmonary artery pressure rose. The superiority of the multivariate technique, using nine measurements simultaneously, was readily demonstrated when compared to the hand measurements. At a constant level of 6% false positives, multivariate analysis allowed a 74% recognition rate of mitral stenosis compared to 44% with hand measurements.