Diagnostic value of electrocardiogram and vectorcardiogram in postinfarction ventricular asynergy

The value of body surface potential maps in detecting abnormal ventricular wall motion

In an effort to enlarge the clinical application of body surface potential maps (BSPMs), the authors studied the relationship between abnormal ventricular wall motion and BSPMs in 98 consecutive patients with angiographically proven coronary artery disease (CAD). Forty-nine of the patients (50%) had wall motion abnormalities as seen on single-plane left cine ventriculograms. During early ventricular depolarization, normal BSPMs have a potential maximum that is greater than the absolute value of the potential minimum; this reverses in late depolarization such that the absolute value of the potential minimum is the greater. The patients showed a significantly early reversal (p less than 0.001), and 55 (56.1%) had abnormal "early reversal" BSPMs. This abnormal "early reversal" is closely related to abnormal ventricular wall motion. Using it as an indicator of abnormal wall motion, the authors obtained the sensitivity, specificity, positive predictive value, and negative predictive value of the following conditions: LAD lesions, LCX, RCA, LAD and RCA lesions, LAD and LCX, and three-vessel disease, and for all patients. A relatively high sensitivity (85%) and specificity (80%) was found in patients with LAD lesions only or multivessel lesions in addition to LAD lesions.

Vectorcardiographic bites. A method for detection and quantification applied on a normal material

Vectorcardiographic bites as an expression of small fibrotic or necrotic areas in the myocardium have been discussed for many years. Distinct definitions of bites and normal limits for bites have, however, not been established. Therefore, an algorithm for computer detection and quantification of bites is presented. To find a bite, sectors of the QRS loop rotating opposite the way of the main part of the loop (eg, a clockwise-rotating sector in an otherwise counterclockwise-rotated loop) are detected. The bite is then delineated, using an iterative procedure. Finally the amplitude, duration, and area of the bite are calculated. The method for detection and quantification was applied on a well-defined normal material to obtain normal limits for bites. The commonly used criterion for an abnormal bite (amplitude greater than or equal to 0.1 mV and duration greater than or equal to 10 msec in the horizontal or sagittal plane) results in a specificity of only 87%. A specificity of 95% is yielded with the criterion of bite amplitude greater than 0.15 mV in the horizontal or sagittal plane.

Prediction of left ventricular ejection fraction using a unique method of chest x-ray and ECG analysis: a noninvasive index of cardiac performance based on the concept of heart volume and mass interrelationship

A reasonably accurate, simple, inexpensive, noninvasive method of determining ejection fraction (EF) is necessary to evaluate left ventricular function in epidemiologic studies and individual patients. Using the concepts of left ventricular mass reflected by precordial R wave summation (M) and left ventricular volume (V) estimated by chest roentgenography in 114 patients with myocardial disease undergoing left ventriculography, EF was predicted with the formula: EF = 63.74 - (2.16.V) + (0.34.M); R2 = 0.69; standard error of the estimate (SEE) = 11. Because angiographic inferior wall motion (IWM) abnormalities significantly affected the results, but inferior Q waves were usually only present in patients having one infarct, a noninvasive technique to predict the presence of inferior wall motion abnormality (IMA) in patients having multiple infarcts was developed and based on the relationship of precordial R wave summation (M) and roentgenographic heart volumenometry (V). By combining V, M, and IMA (which predicted IWM) to determine EF, multiple linear regression analysis showed that EF = 67.30 - (1.56.V) + (0.23.M) - (14.18 IMA) (R2 = 0.77; SEE = 9). Prospective validation of the formula was then done in 139 consecutive individuals, with R2 = 0.49 and SEE = 9. This study demonstrates that routinely performed, simple, inexpensive clinical tests provide data that can be combined by multiple regression analysis to predict resting EF in patients with heart disease affecting the left ventricle. This unique method may allow inexpensive ventricular function screening in large population studies and in addition might provide an independent index of myocardial performance for clinical use, since it reflects the amount of contractile mass per unit of left ventricular volume.(ABSTRACT TRUNCATED AT 250 WORDS)

When is the vectorcardiogram superior to the scalar electrocardiogram?

The clinical usefulness of the vectorcardiogram is well documented by the numerous reports published in the last 3 decades. It has been found more reliable than the electrocardiogram for the diagnosis of atrial enlargement and right ventricular hypertrophy. It is more sensitive than the electrocardiogram in the recognition of myocardial infarction, especially if the infarction is inferior or if it occurs in the presence of left bundle branch block or left anterior hemiblock. It is helpful in the diagnosis of ventricular pre-excitation and in the localization of the bypass tract. Some repolarization abnormalities are more clearly demonstrated by the vector display. However, some information, such as that on cardiac chamber size and myocardial damage, can also be obtained by other noninvasive tests that are often performed on the same patients. With the increasing awareness of cost-effectiveness of various laboratory procedures in medicine, the vectorcardiogram should no longer be considered a routine cardiac test and should be requested only for a specific clinical purpose. When properly utilized, vectorcardiography should remain a valuable diagnostic as well as teaching tool.

Assessment of left ventricular hypertrophy by ECG and VCG in patients with inferior and posterior myocardial infarction. A comparison with echocardiographic data

Electrocardiographic (ECG) and vectorcardiographic (VCG) QRS voltage criteria have been analyzed in 26 patients with inferior and 17 with posterior myocardial infarction (MI) in comparison with left ventricular (LV) mass and global and regional wall motion as assessed by M-mode and two-dimensional (2D) echocardiography. Transverse plane QRS maximal vector correlated significantly with LV mass in patients with both inferior and posterior MI (r = 0.65 and 0.87, respectively, p less than 0.01). A transverse plane QRS maximal vector greater than 1.5 mV correctly recognized 12 of 15 (80%) and 9 of 12 (75%) patients with respectively inferior and posterior MI and LV mass greater than 221 gm. Of the ECG measurements, S V1-2 + R V5-6 correlated moderately with LV mass in patients with inferior MI (r = 0.47), and R V1-2 + R V5-6 correlated moderately with LV mass in those with posterior MI (r = 0.67). ECG and VCG QRS voltage data did not correlate with global and regional LV function as assessed by M-mode and 2D echocardiography. We conclude that: ECG and VCG QRS voltage parameters can be utilized for assessing non-invasively LV enlargement in patients with postero-inferior MI; ECG and VCG QRS voltage parameters should be utilized with caution for analyzing LV function or MI size in postero-inferior MI.