Comparison of the vectorcardiogram with the electrocardiogram in the prediction of left ventricular size

Vectorcardiography-derived index allows a robust quantification of ventricular electrical synchrony

Alteration of muscle activation sequence is a key mechanism in heart failure with reduced ejection fraction. Successful cardiac resynchronization therapy (CRT), which has become standard therapy in these patients, is limited by the lack of precise dyssynchrony quantification. We implemented a computational pipeline that allows assessment of ventricular dyssynchrony by vectorcardiogram reconstruction from the patient’s electrocardiogram. We defined a ventricular dyssynchrony index as the distance between the voltage and speed time integrals of an individual observation and the linear fit of these variables obtained from a healthy population. The pipeline was tested in a 1914-patient population. The dyssynchrony index showed minimum values in heathy controls and maximum values in patients with left bundle branch block (LBBB) or with a pacemaker (PM). We established a critical dyssynchrony index value that discriminates electrical dyssynchronous patterns (LBBB and PM) from ventricular synchrony. In 10 patients with PM or CRT devices, dyssynchrony indexes above the critical value were associated with high time to peak strain standard deviation, an echocardiographic measure of mechanical dyssynchrony. Our index proves to be a promising tool to evaluate ventricular activation dyssynchrony, potentially enhancing the selection of candidates for CRT, device configuration during implantation, and post-implant optimization.

Vectorcardiographic-hemodynamic correlations in adult aortic stenosis

Thirty-nine vectorcardiographic (VCG) data from 45 patients with pure adult aortic stenosis have been tested as to their ability to reflect quantitatively the peak systolic left ventricular pressure (LVPSP), the left ventricular end diastolic pressure (LVEDP), and the X-ray estimated heart volume. VCG was recorded with the axial lead system and simple and multiple linear regression analyses were applied. Eight VCG data correlated significantly (p less than 0.001) with LVPSP, the best indicator being the maximum posterior dislocation in the Z lead (r = 0.65). Through multiple regression analysis a formula was derived which gave a correlation coefficient between observed and calculated pressures of 0.82. The best indicator of LVEDP was the maximum positive P amplitude in the X lead (r = 0.41). The relationship was, however, too poor to have practical significance. A good correlation was found between ST segment dislocation and heart volume (r = 0.65), in good accordance with previous observations as to the effect of right ventricular dilatation on the ECG. The study illustrates how ventricular volume and pressure exert different effects on the ECG, and how all the important hemodynamic aspects in aortic stenosis to some degree are reflected. Only the pressure correlations have, however, practical importance.

Significance of vectorcardiogram in the cardiological diagnosis of the 21st century

Until the mid-1980s, it was believed that the vectorcardiogram presented a greater specificity, sensitivity and accuracy in comparison to the conventional electrocardiogram, in the diagnosis of the different heart diseases. Recent studies revealed that the vectorcardiogram still is superior to the electrocardiogram in very specific situations, such as in the evaluation of electrically inactive areas, in intraventricular conduction disorders combined and/or in association to inactive areas, in the identification and location of ventricular preexcitation, in the differential diagnosis of patterns varying from normal of electrical axis deviation, in the evaluation of particular aspects of Brugada syndrome, and in the estimation of the severity of some enlargements, among others. With the advent of computerized vectorcardiography, a technology that improves the processing and recording method; a future still promising is expected for this methodology. In the fields of education and research, vectorcardiography provided a better and more rational insight into the electrical phenomena that occurs spatially, and represented an important impact on the progress of electrocardiography. Although a few medical centers still use the method as a routine, we hope that the use of this resource will not get lost over time, since vectorcardiography still represents a source to enrich science by enabling a better morphological interpretation of the electrical phenomena of the heart.

Magnetocardiographic indices of left ventricular hypertrophy

OBJECTIVE

We tested the hypothesis that multichannel magnetocardiographic (MCG) mapping can detect and quantify the degree of left ventricular hypertrophy (LVH).

DESIGN

A cross-sectional study.

SETTING

Helsinki University Central Hospital, a tertiary referral center.

PARTICIPANTS

Forty-two patients with pressure overload induced LVH by gender-specific echocardiographic criteria (LVH group), and 12 healthy middle-aged controls.

MAIN OUTCOME MEASURES

MCG QRS-T area integrals and QRS-T angle in magnetic field maps in relation to echocardiographic LVH as well as left ventricular (LV) mass and structure. Conventional 12-lead electrocardiographic (ECG) LVH indices (Sokolow-Lyon voltage, Cornell voltage, Cornell voltage duration product) were assessed for comparison.

RESULTS

MCG QRS- and T-wave integrals provided complementary information of echocardiographic LV mass. Their combination, the QRS-T integral, and the QRS-T angle were increased in patients with LVH and, in those patients, correlated significantly with LV mass indexed to body surface area (r = 0.455;P = 0.002 and r= 0.379; P= 0.013, respectively). A QRS-T integral 16000 fT.s had identical sensitivity of 62% at 92% specificity as the gender-adjusted Cornell voltage duration product of 240 micro V.s for the detection of LVH.

CONCLUSIONS

The MCG method can detect patients with LVH and also quantify the degree of LVH in patients with increased LV mass.

Different effects of temocapril and cadralazine on electrocardiographic voltages and left ventricular mass in patients with essential hypertension

To assess whether electrocardiographic variables are useful to detect the regression of left ventricular (LV) mass after long-term antihypertensive treatment, we related electrocardiographic voltages to echocardiographic variables before and after treatment with an ACE inhibitor, temocapril (TEM), or direct vasodilator, cadralazine (CAD). Twenty-one patients with essential hypertension were treated with either TEM (n = 11) or CAD (n = 10) for one year. LV mass index (LVMI) by echocardiography and Sokolow-Lyon voltage (SV1 + RV5), Cornell voltage (RaVL + SV3) and RV5 + RV6 by standard 12-lead electrocardiographic voltages were determined before and after treatment. Both drugs decreased blood pressure to the same extent. Both Sokolow-Lyon voltage and RV5 + RV6 tended to decrease in the ACE group (40.0 +/- 9.4 to 37.2 +/- 9.4 mm and 44.7 +/- 13.5 to 41.7 +/- 11.7 mm, respectively, N.S.), but not in the CAD group (38.4 +/- 6.8 to 39.7 +/- 7.7 mm and 42.9 +/- 10.4 to 46.8 +/- 11.2 mm, respectively, N.S.). LVMI decreased in the ACE group (-24 +/- 22 g/m2), whereas it increased in the CAD group (37 +/- 27 g/m2, p < 0.01). Change in LVMI was correlated with the changes in RV5 + RV6 and Sokolow-Lyon voltage (r = 0.73, p < 0.01 and r = 0.70, p < 0.01, respectively), but not with that in Cornell voltage. These results indicated that the changes in voltage criteria of RV5 + RV6 and Sokolow-Lyon are useful to assess the change in LVM after antihypertensive treatment in patients with essential hypertension although voltage variables in electrocardiogram were not sensitive to detect changes in LVMI.

Electrocardiographic identification of increased left ventricular mass by simple voltage-duration products

OBJECTIVES

This study was conducted to validate the hypothesis that the product of QRS voltage and duration, as an approximation of the time-voltage area of the QRS complex, can improve the electrocardiographic (ECG) detection of echocardiographically determined left ventricular hypertrophy and to further assess the relative contribution of QRS duration to the ECG detection of hypertrophy.

BACKGROUND

The ECG identification of left ventricular hypertrophy has been limited by the poor sensitivity of standard voltage criteria alone. However, increases in left ventricular mass can be more accurately related to increases in the time-voltage area of the QRS complex than to changes in QRS voltage or duration alone.

METHODS

Standard 12-lead ECGs and echocardiograms were obtained for 389 patients, including 116 patients with left ventricular hypertrophy. Simple voltage-duration products were calculated by multiplying Cornell voltage by QRS duration (Cornell product) and the 12-lead sum of voltage by QRS duration (12-lead product).

RESULTS

In a stepwise logistic regression model that also included Cornell voltage, Sokolow-Lyon voltage, age and gender, QRS duration remained a highly significant predictor of the presence of left ventricular hypertrophy (chi-square 26.9, p < 0.0001). At a matched specificity of 96%, each voltage-duration product significantly improved sensitivity for the detection of left ventricular hypertrophy compared with simple voltage criteria alone (Cornell product 37% vs. Cornell voltage 28%, p < 0.02, and 12-lead product 50% vs. 12-lead voltage 43%, p < 0.005). Sensitivities of both the Cornell product and the 12-lead product were significantly greater than the 27% sensitivity of QRS duration alone (p < 0.01 vs. p < 0.001), the 20% sensitivity of a Romhilt-Estes point score > 4 (p < 0.001) and the 33% sensitivity of the best-fit logistic regression model in this cohort (p < 0.05 vs. p < 0.001).

CONCLUSIONS

QRS duration is an independent ECG predictor of the presence of left ventricular hypertrophy, and the simple product of either Cornell voltage or 12-lead voltage and QRS duration significantly improves identification of left ventricular hypertrophy relative to other ECG criteria that use QRS duration and voltages in linear combinations.

Electrocardiographic diagnosis of left ventricular hypertrophy by the time-voltage integral of the QRS complex

OBJECTIVES

This study was conducted to test the hypothesis that the time-voltage integral of the QRS complex can improve the electrocardiographic (ECG) identification of left ventricular hypertrophy.

BACKGROUND

Standard ECG criteria have exhibited poor sensitivity for left ventricular hypertrophy at acceptable levels of specificity. However, left ventricular mass may be more closely related to the time-voltage integral of the summed left ventricular dipole than to QRS duration or voltages used in standard ECG criteria.

METHODS

Standard 12-lead ECGs, orthogonal lead signal-averaged ECGs and echocardiograms were obtained in 62 male control subjects without left ventricular hypertrophy and 51 men with left ventricular hypertrophy defined by echocardiographic criteria (indexed left ventricular mass > 125 g/m2). Voltage of the QRS complex was integrated over the total QRS duration in leads X, Y and Z to calculate the time-voltage integral of each orthogonal lead, of the maximal spatial vector complex and of the horizontal, frontal and sagittal plane vector complexes.

RESULTS

At matched specificity of 99%, the 73% (37 of 51) sensitivity of the time-voltage integral of the vector QRS complex in the horizontal plane was significantly greater than the 10% sensitivity of the Romhilt-Estes point score, the 16% sensitivity of QRS duration alone, the 22% sensitivity of Cornell voltage, the 33% sensitivity of the 12-lead sum of QRS voltage and the 37% sensitivity of Sokolow-Lyon voltage (each p < 0.001). Sensitivity of the horizontal plane time-voltage integral was also greater than the 10% to 51% sensitivity of the time-voltage integral calculated in the individual X, Y or Z leads (p < 0.01 to < 0.001), the 18% and 35% sensitivity of the time-voltage integrals of the frontal and sagittal plane vectors (p < 0.001) and the 49% sensitivity of the time-voltage integral of the maximal spatial vector complex calculated from all three orthogonal leads (p < 0.001). Comparison of receiver operating characteristic curves confirmed that the superior performance of the horizontal plane time-voltage integral relative to standard and other signal-averaged criteria was independent of partition value selection.

CONCLUSIONS

These findings suggest that use of the time-voltage integral of the QRS complex, a method that can be readily implemented on commercially available computerized ECG systems, can improve the accuracy of ECG methods for the identification of left ventricular hypertrophy.

Electrocardiographic detection of left ventricular hypertrophy by the simple QRS voltage-duration product

OBJECTIVES

The object of this study was to assess the hypothesis that the product of QRS voltage and duration, as an approximation of the time-voltage integral of the QRS complex, can improve the electrocardiographic (ECG) identification of left ventricular hypertrophy.

BACKGROUND

Electrocardiographic identification of left ventricular hypertrophy has been limited by the poor sensitivity of standard voltage criteria. However, increases in left ventricular mass can be more closely related to increases in the time-voltage integral of the summed left ventricular dipole than to changes in voltage or QRS duration alone.

METHODS

Antemortem ECGs were compared with left ventricular mass at autopsy in 220 patients. There were 95 patients with left ventricular hypertrophy, defined by left ventricular mass index > 118 g/m2 in men and > 104 g/m2 in women. The voltage-duration product was calculated as the product of QRS duration and Cornell voltage (Cornell product) and the 12-lead sum of QRS voltage (12-lead product).

RESULTS

At partitions with a matched specificity of 95%, each voltage-duration product significantly improved sensitivity for the detection of left ventricular hypertrophy when compared with simple voltage criteria alone (Cornell product 51% [48 of 95] vs. Cornell voltage 36% [34 of 95], p < 0.005 and 12-lead product 45% [43 of 95] vs. 12-lead voltage 31% [30 of 95], p < 0.001). Sensitivity of both the Cornell product and 12-lead product was significantly greater than that found for QRS duration alone (28%, 27 of 95, p < 0.005) and the Romhilt-Estes point score (27%, 26 of 95, p < 0.005), and compared favorably with the sensitivity of the complex Cornell multivariate score (44%, 42 of 95, p = NS). Comparison of receiver operating characteristic curves demonstrated that improved performance of the voltage-duration products for the detection of left ventricular hypertrophy was independent of test partition selection. In addition, test performance of the voltage-duration products was not significantly affected by the presence or absence of a bundle branch block.

CONCLUSIONS

These data suggest that the simple product of either Cornell or 12-lead voltage and QRS duration can identify left ventricular hypertrophy more accurately than can voltage or QRS duration criteria alone and may approach or exceed the performance of more complex multiple regression analyses.

High-frequency analysis of the signal-averaged ECG. Correlation with left ventricular mass in rabbits

Standard electrocardiographic (ECG) criteria have exhibited poor correlation with left ventricular mass and poor sensitivity for left ventricular hypertrophy at acceptable levels of specificity. To assess the ability of the high-frequency filtered signal-averaged ECG to improve ECG correlation with left ventricular mass, signal-averaged orthogonal lead recordings in 29 normal rabbits and seven rabbits with left ventricular hypertrophy due to chronic aortic regurgitation were compared with left ventricular mass corrected for body weight. Voltage of the vector QRS complex was integrated over the total duration of the QRS after separate filtering with standard frequency (0-100 Hz) low-pass and high-frequency (44 Hz) high-pass filters. Measurement of individual X, Y, and Z lead R and S wave voltage was performed on averaged, standard frequency filtered complexes, and the maximal spatial vector magnitude was determined from the standard frequency filtered vectors. Voltage of the 44 Hz high-pass filtered vector QRS complex integrated over the total duration of the QRS (high-frequency vector integral) correlated closely with indexed left ventricular mass (r = 0.84, p less than 0.0001), significantly better than the correlation of standard frequency vector integral or maximal spatial vector magnitude voltages (r = 0.35 and r = 0.61, each p less than 0.01 vs high-frequency vector integral) and the correlation of orthogonal lead X R wave or lead Y S wave voltages (r = 0.55 and r = 0.37, respectively, each p less than 0.01 vs high-frequency vector integral).(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiographic diagnosis of chamber enlargement

The purpose of this article is to review the changing role of the electrocardiogram in the diagnosis of cardiac chamber enlargement. Electrocardiographic criteria for the diagnosis of ventricular hypertrophy and atrial enlargement are reviewed in relation to autopsy, angiographic, echocardiographic and imaging findings. The electrocardiographic theory underlying the recognition of hypertropphy or dilation incorporates a number of sound physical principles that may lead to meaningful correlations with the tissue mass, chamber diameter and intracardiac blood volume. However, there are limiting factors related to the variable orientation of the heart in the chest, variable extracardiac factors and nonspecificity of each depolarization and repolarization abnormality used in the diagnosis of hypertrophy or dilation. This explains the superiority of the new noninvasive methods, in particular echocardiography, in the diagnosis of hypertrophy. Echocardiography is superior to electrocardiography in the detection of mild hypertrophy, and is more useful in the serial follow-up of changes during progression or regression of chamber enlargement.

Changes in pacing threshold and R wave amplitude after transvenous catheter countershock

Transvenous electrode catheter countershock in patients with recurrent ventricular tachyarrhythmias may be followed by transient bradycardia and require temporary pacing with a catheter. The serial changes in R wave amplitude and stimulation threshold after catheter countershock in 11 halothane-anesthetized open chest dogs ranging in weight from 11.8 to 24 kg were studied. Ventricular fibrillation was electrically induced and followed by catheter defibrillation using nonsynchronized trapezoidal waveform (65% tilt) current discharge in incremental doses (5 to 50 J). Significant decreases in bipolar R wave amplitude (8.3 +/- 1 versus 2 +/- 0.2 mV, p less than 0.001) and increases in stimulation threshold (1 +/- 0.1 versus 2.3 +/- 0.4 V, p less than 0.001) were observed using the countershock catheter 15 seconds after countershock; these changes persisted for up to 10 minutes. To determine whether these changes were localized to the defibrillating catheter and whether they were species-specific, a second electrode catheter was positioned in the right ventricle distant from the countershock catheter in five pigs. Increases in stimulation threshold were observed only at the countershock catheter, suggesting that changes were secondary to local changes at the catheter-myocardium interface. No significant change in R wave amplitude or stimulation threshold was observed at the countershock catheter in three pigs given transthoracic shocks (60 to 250 J). It is concluded that current discharge through the countershock catheter results in a significant temporary reduction in R wave amplitude and an increase in pacing threshold. This may make pacing through the countershock catheter unreliable after shock delivery.

Electrocardiographic changes after physical training in patients with myocardial infarction

Electrocardiographic voltage measurements were performed in 24 men with an inferior myocardial infarction before and after 14 +/- 0.5 weeks of physical training. Oxygen uptake at peak exercise increased 42% and heart rate at rest was significantly decreased after training. Increases were found in the magnitude of the R waves in leads II, aVF and V4 to V6; of the S wave in leads V1 and V3; of the T waves in V5 and V6; and of the Sokolow index of QRS voltage. Also, the magnitude of the mean electrical vector in the frontal plane was significantly higher after training. These data were compared with those derived from two electrocardiographic tracings, separated by an average of 19 +/- 1.5 weeks, of 20 other patients with an inferior myocardial infarction who were comparable in age, weight, risk factor and delay between infarction and first examination, but who were not trained. When the electrocardiographic changes between the two observations were compared for the two groups, the trained patients show significant increases in the magnitude of the R wave in the left precordial leads, and leads II and aVF and the Sokolow voltage criterion; in the magnitude of the T wave in leads V5 and V6; and in the magnitude of the mean electrical vector in the frontal plane. It is concluded that physical training in patients with myocardial infarction can alter cardiac structure, as evaluated by voltage measurements on the electrocardiogram.

Reliability of echocardiographic and electrocardiographic parameters in assessing serial changes in left ventricular mass

A reliable noninvasive index of left ventricular mass would be useful in following patients with valvular heart disease and left ventricular hypertrophy. We reviewed concurrent electrocardiograms and echocardiograms from 54 subjects, 39 patients with aortic or mitral valve disease and 15 normal subjects. Pre- and early postoperative echocardiographic estimates of left ventricular mass in 17 patients who had valve replacements correlated well (r = 0.96, p less than 0.001) and demonstrated little change in mean values despite altered left ventricular dimensions. Echocardiographic estimates of left ventricular mass were, therefore, used as a standard for evaluating other noninvasive indices. Precordial electrocardiographic voltage showed a weak correlation with left ventricular mass in the study group as a whole (r = 0.59, p less than 0.001), but no correlation in patients with volume overload (r = 0.36, p = NS). In 18 patients who had preoperative and three separate postoperative studies at least eight weeks apart, changes in left ventricular cross-sectional area (an index of left ventricular mass which corrects for changes in left ventricular volume) closely followed alterations in left ventricular mass. However, changes in posterior wall and interventricular septal thickness often resulted from altered ventricular volume and did not accurately reflect directional changes in left ventricular mass. Serial changes in electrocardiographic voltage were similarly unreliable. We conclude that left ventricular mass and cross-sectional area by echocardiography allow accurate noninvasive assessment of left ventricular mass, whereas wall thickness and electrocardiographic changes do not.

Hypertrophy or dilatation? A vectorial analysis of echocardiographically determined left ventricular enlargement

Echocardiograms (ECHO) and Frank vectorcardiograms (VCGs) were obtained in three groups of patients: Group I (n = 16), concentric left ventricular hypertrophy (LVH) with increased interventricular septal (IVS) and left ventricular posterior wall (LVPW) thickness in the presence of a normal left ventricular internal dimension (LVID); Group II (n = 17), left ventricular dilatation (LVD) with an enlarged LVID, normal IVS and LVPW thickness, and Group III (n = 22), no catheterization evidence of heart disease with normal IVS, LVPW and LVID. VCGs were analyzed with respect to magnitude of the QRS maximal deflection vector (MDV) and +/- 10 msec QRS vectors, horizontal plane (HP) maximal posterior force, time of HP MDV inscription, distal and proximal HP loop areas and HP loop configuration utlizing criteria of Varriale et al. The results indicate that: 1) HP QRS vector magnitude cannot reliably differentiate concentric LVH from isolated LVD and 2) proximal-distal loop area relationships and pattern of the HP QRS loop, when reviewed together, are superior to other criteria for distinguishing whether ECHO determined LVH or LVD is the primary correlate of an enlarged left ventricle.

Eelectrocardiographic correlates of ultrasonically increased septal, left ventricular posterior wall and left ventricular internal dimensions

The electrocardiograms (ECG) of 64 subjects who exhibited an echocardiographically demonstrable increase in thickness of the interventricular septum and left ventricular posterior wall (Group 1, 22 patients), isolated left ventricular internal dimension (Group 2,26 patients), combined wall thickness and chamber diameter (Group 3, 2 patients), and septal thickness, (Group 4, asymmetric septal hypertrophy, 14 patients) were reviewed in order to determine sensitivity of ECG criteria for the diagnosis of left ventricular hypertrophy (LVH) proposed in 1949 by Sokolow and Lyon (13), in 1968 by Romhilt and Estes (14), and in 1973 the New York Heart Association (15). Relative sensitivity of the three methods was as follows: Total group, NYHA (77%) greater than Sokolow and Lyon (67%) greater than Romhilt and Estes (58%); Group 1, NYHA (91%) greater than Sokolow and Lyon (73%) greater than Romhilt and Estes (54%); Group 2, NYHA and Sokolow and Lyon (65%) greater than Romhilt and Estes (61%); Group 4, NYHA (79%) greater than Sokolow and Lyon (64%) greater than Romhilt and Estes (57%). We conclude that 1)ECG criteria of the NYHA for the diagnosis of LVH correlate best with an increase of ultrasonically determined septal, left ventricular posterior wall or left ventricular internal dimensions when compared with voltage criteria of Sokolow and Lyon and the point score system of Romhilt and Estes; and 2) isolated increase of left ventricular internal dimension, in the absence of thickened septum or posterior left ventricular wall, frequently results in ECG criteria compatible with the diagnosis of LVH.

QRS voltage of the electrocardiogram and Frank vectorcardiogram in relation to ventricular volume

Left ventricular volumes were estimated in 59 patients, who were investigated by single plane ventriculography and coronary arteriography. The relation of the left ventricular end-diastolic volumes to the QRS voltage of the 12-lead electrocardiograms and Frank vectorcardiograms was examined. It was found that the maximum spatial QRS voltage and the R wave voltage of leads V5 and V6 in patients without left ventricular hypertrophy were inversely correlated with end-diastolic volume. This inverse relation of QRS voltage and left ventricular volume may explain loss of QRS voltage with dilatation of the heart. In patients with left ventricular hypertropy QRS voltage is usually positively correlated with the degree of hypertrophy, but there is no significant correlation in the presence of cardiac dilatation. If the results of this study are extrapolated to patients with left ventricular hypertrophy and cardiac dilatation, then the inverse correlation of volume and QRS voltage may reduce the diagnostic sensitivity of unipolar chest lead and vectorcardiographic criteria of left ventricular hypertrophy.

Prediction of pulmonary arterial pressures from electrovectorcardiographic data in pediatric patients with rheumatic mitral valve disease

The Frank vectorcardiogram (VCG) and the electrocardiogram (ECG) were used to predict pulmonary arterial pressures in 30 pediatric patients with rheumatic mitral valve disease. The patients' ages ranged from eight to 14 1/2 years. Eleven were male and 19 were female. Sixteen had mitral stenosis, eight had mitral regurgitation and six had mitral stenosis and regurgitation. Mean pulmonary arterial wedge pressure ranged from 5-32 mmHg. All patients underwent complete catheterization and angiocardiographic study. None had significant gradient across the right ventricular outflow tract. Right maximum spatial vector (Rmsv) was calculated using Frank VCG.R in V1 and S in V5 of ECG were also measured. Rmsv, RV1, and SV5 were correlated with pulmonary arterial pressures (systolic, diastolic and mean). Pulmonary artery systolic pressure and Rmsv bear the best correlation (r=0.773). The correlation coefficient for pulmonary artery diastolic pressure and Rmsv was 0.698. Rmsv as calculated from Frank VCG is useful in prediction of pulmonary arterial pressures (systolic and diastolic) in pediatric patients with rheumatic mitral valve disease.

Correlation of left ventricular mass determined by echocardiography with vectorcardiographic and electrocardiographic voltage measurements

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