Evolutive study of the VCG in the first week of the normal newborn infant (author's transl)]

The vectorial and morphological variations of the VCG (Frank method) during the first seven days of life of sixteen normal newborn infants were analyzed. A byphasic distribution of the QRS vectors in the horizontal plane was found at birth. Successive observations showed a rising of initial forces of left septal activation and a slight increase of left parietal forces. The T loop variations were more remarkable, being probably correlated with rapid postnatal hemodynamic modifications. After a few days the T loop was oriented posteriorly and to the left, not changing this direction for many year. The P loop did not differ from the adult's in the majority of cases. Sometimes it showed a figure-or-eight rotation in the horizontal plane, probably due, according to the authors, to a different pathway of atrial activation.     

The normal pediatric Frank orthogonal electrocardiogram: variations according to age and sex

Quantitative computerized analysis of QRS and ST-T parameters of the Frank orthogonal electrocardiogram and vectorcardiogram was undertaken in a large series of 1317 normal infants, children and adolescents stratified according to age and sex. This study confirms the influence of these two constitutional variables, age and sex, over the normal VCG in the whole time span between birth and late adolescence. As children mature, the mid-portion of the spatial QRS loop shifts leftward and posteriorly with relatively little change in the initial and terminal vectors. The spatial T loop shifts anteriorly but at a different rate in males and in females. Unidirectional changes in many amplitude parameters are observed until age 19 in males whereas in females these changes stop earlier or even show a reverse trend around puberty, leading to more important differences between adolescent males and females. Sex-related differences are the most marked for parameters representing the repolarization process. Infants under six months of age form a distinct group with larger dispersions and more disparate variations in the values of vectorcardiographic parameters than in older children. In the newborn period larger sample size might be necessary in order to reduce the normal ranges of vectorcardiographic parameters.     

Evaluation of frontal plane QRS loop rotation in vectorcardiographic diagnosis

The diagnostic usefulness of frontal plane QRS loop rotation in the Frank vectorcardiogram (VCG) was evaluated in a series of 598 normal subjects, 301 patients with postero-diaphragmatic myocardial infarction (PDMI), 84 with lateral myocardial infarction (LMI), 844 with left ventricular hypertrophy (LVH), and 190 with right ventricular hypertrophy (RVH). In normals 62% showed clockwise (CW) rotation of the QRS loops; 28%, figure-of-eight; and 10%, counterclockwise (CCW). The respective distributions were 68%, 23%, and 9% in PDMI; and 23%, 40%, and 37% in LMI. In normals the superior and inferior limits (96% range) of the maximal QRS vector angles were +15° and +79° in VCGs with CW rotation, +12° and +62° in VCGs with figure-of-eight, and −4° and +58° in VCGs with CCW rotation. Based on these limits, approximately half of PDMI cases (with 2% false positives) and a little over two-thirds of LMI cases (with 4% false positives) could be separated from normal. In LVH and RVH groups without clinical evidence of ischemic heart disease, the superior and inferior limits (96% range) of the maximal QRS vector angles differed from those of normal. In LVH such limits were +1° and +86° in VCGs with CW rotation, +12° and +62° in VCGs with figure-of-eight, and −86° and +48° in VCGs with CCW rotation. The respective limits in RVH were +13° and −160°, −3° and +76°, and −30° and +65°. Thus, when LVH or RVH is present, the foregoing limits separating PDMI or LMI from normal need to be modified accordingly.Results of the study demonstrate the diagnostic significance of QRS rotation analysis in the frontal plane VCG. These findings should prove useful as the standard of reference for clinical interpretation of the Frank VCG.     

Assessment of echocardiographic left atrial enlargement in patients with atrial fibrillation. An electrovectorcardiographic study.

Standard 12 lead electrocardiograms (ECG) and timed Frank vectorcardiograms (VCG) were recorded in 53 subjects with atrial fibrillation. Thirty-eight patients had echocardiographically documented left atrial enlargement (greater than 4.0 cm) and 15 patients had normal atrial dimensions. The magnitude of the largest "f" wave component during an average cycle length was measured in lead V1 of the ECG and the horizontal plane VCG running loop. Relative sensitivies for detection of left atrial enlargement were: VCG, 25/38 (66%) and ECG 10/38 (26%). An enlarged left atrial internal dimension was diagnosed by the VCG alone in 21 of the 38 subjects (55%). In the group of 15 patients with normal echocardiographic left atrial internal dimensions the prevalence of ECG false positive diagnosis for enlarged left atrial size was 6% in contrast with 0% for the VCG. It is concluded that: 1) the timed Frank VCG is superior to the ECG for the detection of echocardiographically demonstrable left atrial enlargement; 2) the timed VCG and ECG represent complementary techniques for identifying patients with abnormally large left atria; and 3) large fibrillatory waves are rarely observed on the ECG or VCG when the left atrial internal dimension is echographically normal.     

Prediction of right ventricular systolic pressure in pulmonary stenosis from combined vectorcardiographic data

In 38 patients with isolated unoperated pulmonary stenosis a systematic search was made for optimal VCG criteria for the prediction of peak systolic right ventricular pressure. Fifty VCG measurements, seven ECG measurements, and age of each patient were entered into a stepwise multiple regression computer program.The best individual predictors were found to be the QRS loop rotation in the horizontal plane and the closely related QRS dislocation along the 135 to 315 degree horizontal plane axis (r = 0.78). Five VCG criteria were better than the best ECG criterion (R V₁, r = 0.72). Thirty-three of the 58 variables showed significant correlations with the pressure (p < 0.01). Since the confidence intervals are large with this sample size and degree of correlation, conclusions regarding the superiority of one predictor vs. another should be drawn with great care.The multivariate equation selected by the computer involved four VCG variables and age; this improved the correlation coefficient to 0.93. This improvement from data combination is larger than in previous studies, probably because all variables were given equal opportunity to enter the equation.The results were tested on a secondary sample of 19 patients with pulmonary stenosis as their main cardiac lesion. Although this sample was less homogeneous, the formula-derived pressure estimates remained reasonably good (r = 0.88). The study suggests that the diagnostic power of ECG and VCG could be increased through the proper combination of easily obtainable measurements.     

Echocardiographic left atrial enlargement. Comparison of vectorcardiogram and electrocardiogram for detection

Standard electrocardiograms (ECG) and Frank vectorcardiograms (VCG) were obtained in 43 consecutive patients in sinus rhythm who had echocardiographic evidence of left atrial enlargement (left atrial internal dimension greater than 4.0 cm; x +/- 1SD = 4.7 +/- 0.5 cm). High gain VCG P loop measurements for the study group were: maximal posterior magnitude, 0.11 +/- 0.03 mv; duration, 106 +/- 14 msec and ratio of maximal posterior to maximal anterior P vector magnitudes, 3.2 +/- 1.4. Thirty of 43 (70%) patients with echocardiographic determined left atrial enlargement had VCGs diagnostic of that condition. Utilizing New York Heart Association criteria for left atrial enlargement, 17 of 43 patients (40%) had ECGs which were diagnostic. Fifteen of 43 (35%) subjects manifested both ECG and VCG criteria for left atrial enlargement and only two patients had diagnostic ECGs and normal VCGs. It is concluded that analysis of high gain VCG P loops provides a 30% higher yield for the diagnosis of echocardiographically determined left atrial enlargement when compared with P wave examination on the standard ECG.     

The anterior displacement of the QRS loop as a right ventricular conduction disturbance. Electrophysiologic and vectorcardiographic study in man

Anterior displacement (AD) of the QRS horizontal loop (Frank VCG method) was induced by programmed right atrial stimulation (PRAS) in 15 cases. When AD occurred we noticed changes of the terminal QRS vectors and of the T loop similar to those observed in incomplete right bundle branch block (RBBB). The increasingly anticipated extrastimuli induced progressively the AD and then progressive degrees of RBBB. The anterior shifting of the efferent limb never appeared after the induction of RBBB. A left conduction disturbance never appeared after the AD. In cases of supposed incomplete left bundle branch block (i.e. left ventricular hypertrophy) the QRS duration decreased when the AD was induced. Therefore, the AD induced by PRAS and probably those observed in some clinical cases are due to a right ventricular conduction disturbance.     

正常变异心电图ST段及T波改变与心向量图 横面T环顺钟向运行的关系

目的了解正常变异心电图(ECG)ST段及T波(ST－T)改变与心向量图(VCG)横面T环顺钟向运行(顺转)的关系。方法对122例VCG横面T环顺转及可转向并有ECGST－T改变者进行4种状态下的ECG检测。结果VCG横面T环顺转及可转向者的ECGST－T改变,可通过口服普萘洛尔、变换体位或运动试验,使之恢复正常,与对照组相比,差异有非常显著性意义(P＜0.01)。结论ECGST－T改变通过矫正而恢复正常者,部分考虑与心脏发育欠成熟、心脏神经功能调节不良有关。VCG检查可帮助正常变异ECGST－T改变的诊断。     

Comparison of the electrocardiogram and vectorcardiogram for the diagnosis of left atrial enlargement.

Standard 12 lead electrocardiograms (ECG) and Frank vectorcardiograms (VCG) were recorded in 21 consecutive patients with mitral valvular disease and angiographically documented left atrial enlargement. Comparative sensitivities for the detection of left atrial enlargement were: diagnostic, ECG = 6/21 (29%), VCG = 14/21 (67%); suggestive, ECG = 3/21 (14%), VCG = 2/21 (9%); non-diagnostic, ECG = 12/21 (57%), VCG = 5/21 (24%). It is concluded that the Frank atrial vectorcardiogram is superior to the standard electrocardiogram for the diagnosis of left atrial enlargement.     

The anteriorly oriented horizontal vector loop: The problem of distinction between direct posterior myocardial infarction and normal variation

An attempt was made to distinguish the vectorcardiogram of a direct posterior myocardial infarction from an anterior horizontal loop that is known to occur in over 20 per cent of normal subjects. Patients with anterior horizontal QRS loops and arteriographic evidence of complete occlusion of the right coronary artery, the posterior descending artery, or dominant left circumflex coronary artery were compared to normal individuals with anterior vector loops in the horizontal plane. Nine patients were thought to have a direct posterior infarction; 13 patients were thought to be normal. The association of an abnormal frontal plane QRS loop indicative of a diaphragmatic infarction (5 of 9 patients) implied an associated direct posterior infarction. Otherwise, no differences were observed in the two groups. Specifically, in the horizontal plane, the 20, 30, 40, 50, and 60 msec. vectors, both magnitude and direction, were similar. Also the maximum QRS vector, half-area vector, anterior accession time, QRS loop rotation, T-loop angle, and rotation and magnitude of the maximum anterior, maximum posterior, and maximum right-ward vectors of the QRS loop were similar in both groups. It appears, therefore, that the previously established criteria for the vectorcardiographic diagnosis of a direct posterior myocardial infarction, in general, adequately describes the vectorcardiogram of a direct posterior infarction; but fails to distinguish it from the anteriorly oriented vectorcardiogram of normal individuals which occurs frequently enough to make the importance of this distinction a practical clinical problem.     

The normal pediatric Frank orthogonal electrocardiogram: influence of weight, height and chest circumference

The influence of body weight, height and chest circumference on the pediatric Frank vectorcardiogram (VCG) was investigated in a population of 1317 normal infants, children and adolescents. Simple linear regression analysis showed that 94, 96 and 57 VCG variables were significantly correlated with weight, height and chest circumference, respectively. These numbers were reduced to 10, 18 and 6 VCG variables after a stepwise multiple correlation analysis. The relationship between the VCG and the somatic variables was also studied in ten different age/sex subgroups. Simple regression analysis showed a residual significant correlation between the VCG and all three somatic variables in each group. The multiple correlation analysis allowed us to define a minimum set of VCG variables, from one to six, which could explain all the variation produced by the somatic variables. The coefficient of multiple correlation between VCG and weight was the highest in babies 0 to 6 months old (R = 0.73). For height, the strongest correlation was found in females two to five years old (R = 0.76). In subjects older than two years of age, the correlation between chest circumference and VCG (R = 0.30 to 0.69) was weaker than between VCG and pediatric VCG after stratification for age and sex, especially in the youngest groups.     

Frank vectorcardiogram in common ventricle: Correlation with anatomic findings

The influence on the Frank vectorcardiogram of anatomic features in common ventricle was analyzed by comparison of Frank vectorcardiograms in 51 patients who had common ventricle with those of 36 patients who had large ventricular septal defect, 14 of whom had levotransposition of the great arteries and 22 of whom had dextrotransposition. Frank vector loops in common ventricle differed from those in ventricular septal defect by the frequent occurrence of clockwise horizontal rotation, most common in patients with type C common ventricle (no outflow chamber). There was a statistically significant difference in the amplitude of early forces between patients with common ventricle and those with large ventricular septal defect. The degree of overlap of vectorcardiographic features between the two groups is sufficiently great that the vectorcardiogram has limited usefulness in establishing the diagnosis of common ventricle in any individual patient.     

Vectorcardiographic diagnosis and electrocardiographic correlation in left ventricular asynergy due to coronary artery disease. I. Severe asynergy of the anterior and apical segments.

The transverse plane QRS loop vectorcardiogram (VCG) was analyzed in 102 consecutive patients, angiographically proven to have coronary artery disease (CAD), whose right anterior oblique left ventriculogram showed severe asynergy (akinesis or marked hypokinesis) of the anterior and apical segments. Eighty-four of the 102 loops were considered to be diagnostic of severe asynergy because similar loops were not found in patients with CAD with less severe asynergy of either or both segments or in normal control subjects. Eighty-two of the 84 showed a uniformly abnormal pattern. Posterior vectors exhibited partial or complete clockwise "rotation" and were much more prominent than early anterior forces. In fact, the latter were often absent. In the other two VCG's at least the early half of the loop displayed prominent anterior vectors. The ECGs showed marked variability of the QRS in leads V-2-V-6. Abnormal Q waves were present in only 63 of the 102. The numbers of these leads showing abnormal Q waves varied from one to all of these positions.     

Vectorcardiographic criteria for the diagnosis of anterior myocardial infarction.

Frank lead vectorcardiograms (VCG) from four carefully selected patient subgroups (226 patients) were analyzed to develop optimal criteria for the diagnosis of anterior myocardial infarction. Specificity was evaluated using 100 healthy volunteers under age 30 and 80 patients with normal left ventriculogram and normal coronary arteriograms. Sensitivity was determined using 25 patients with evolutionary ST-T wave changes (V1-2), and LDH and CPK isoenzyme evidence of acute myocardial infarction; and 21 patients with anterior wall akinesia or dyskinesia and greater than 70% occlusion of the left anterior descending coronary artery. Patients with VCG evidence of bundle branch block, left or right ventricular hypertrophy were excluded. The criterion for the diagnosis of anterior myocardial infarction which was found to give the highest sensitivity with greater than or equal to 95% specificity was: initial anterior QRS forces must not exceed 0.1 mV in maximal anterior amplitude and also must not exceed 24 msec in duration. The performance of this proposed criterion was then tested using four similarly defined patient subgroups consisting of a total of 222 patients. The incidence of false positive diagnosis in these test subgroups was less than 1% with a sensitivity of greater than 95%. The overall performance of the proposed criterion was found to be significantly superior to both the widely accepted VCG and ECG criteria for anterior myocardial infarction. Thus, this quantitative criterion using both time and duration of initial anterior forces is both a highly specific and a sensitive indicator of anterior myocardial infarction.     

Electro-vectorcardiographic analysis of the negative, diphasic and bifid T wave in right precordial leads in young subjects

Morphology, genesis and incidence of isolated T wave abnormalities on right precordial leads of healthy young individuals were studied in this work. ECG were obtained from 1510 healthy subjects aged 14 to 40 years consecutively submitted to a cardiological evaluation in order to assess their fitness for sport. In 510 of them a VCG was made too. The results showed that T waves were rarely negative beyond V1 (0.46%) and even more rarely negative from V1 to V3 (0.13%); diphasic T waves were present in 2.38% and bifid T waves in 6.15% of our cases. The T loop of VCG tended to be more posteriorly displaced and evolved from a counterclockwise to a clockwise rotation as the presence of negative T waves spread toward left on precordial leads. The "+-" type of diphasic T wave corresponded to a counterclockwise rotation of the T loop, the "-+" type to a clockwise rotation. Bifid T waves were associated with figure of eight or "arched" T loops of VCG. The T loops of those subjects who underwent a second evaluation after several years tended to be displaced more anteriorly, with counterclockwise rotation. The causes of these T wave abnormalities have not been clearly explained yet, even if a slight delay in the right final vectors was present in the majority of our cases.