QRS Loop Research Articles

A physiological approach to vectorcardiographic recognition of ventricular hypertrophy.

With the use of a substantially simplified model of human heart activation, portions of the QRS loop are shown to be related to successive stages of activation. Durations of these portions, separated from one another by deflection points of the QRS loop, called a, b, c, and d are shown to be helpful in differentiating between QRS loops of ventricular hypertrophy and normal QRS loops.

Change in the frontal QRS axis with changes in the anatomic positions of the heart

Changes in the frontal QRS axis with change in heart position were observed in individuals in two positions: standing at deep inspiration and supine after quiet expiration. Heart position was described by the predicted QRS axis, a value derived from the frontal anatomic (long) axis of the heart corrected for an estimate of horizontal anatomic deviation away from the frontal plane. Change in heart position was associated with a magnified shift of the frontal QRS axis. For every degree of change in the anatomic axis, the frontal QRS axis varied by about 3°. This relation held at frontal QRS axes from −30° to +105°. When only the frontal anatomic axis was measured, the association between the long axis and frontal QRS axis held until the frontal QRS axis was decreased to about 20°. From that point on, further decrease in the frontal QRS axis could occur without apparent change in the long axis of the heart. On this basis a hypothetical model was developed to show that longitudinal rotation could cause the frontal QRS axis to deviate from +30° to −30° with counterclockwise longitudinal heart rotation. However, the opposite longitudinal rotation was observed at surgery and in cadaver hearts with elevation of the diaphragm. From these findings it was concluded that:o1.Change in heart position will cause deviation of the frontal QRS axis throughout its normal range.2.About 3° of change in the frontal QRS axis is caused by each degree of positional change of the heart.3.With shift of the frontal QRS axis to the left, the QRS loop undergoes counter-clockwise longitudinal rotation. This rotation of the loop is in the opposite direction to the longitudinal rotation which occurs as the heart is rotated toward the horizontal. Change in heart position will cause deviation of the frontal QRS axis throughout its normal range. About 3° of change in the frontal QRS axis is caused by each degree of positional change of the heart. With shift of the frontal QRS axis to the left, the QRS loop undergoes counter-clockwise longitudinal rotation. This rotation of the loop is in the opposite direction to the longitudinal rotation which occurs as the heart is rotated toward the horizontal.

Alterations in QRS during ischemia of the left ventricular free-wall in goats

Summary X, Y , and Z axis electrocardiograms, spatial magnitude and spatial velocity electrocardiograms and QRS loops in three planes were recorded from goats before and during ischemia of the left ventricular free-wall produced by injection of ceramic microspheres into branches of the left circumflex coronary artery. Epicardial electrograms were recorded from ischemic and nonischemic regions of the left ventricle to determine time of arrival of depolarization at epicardial sites subjacent. Ischemia produced tardy and unopposed activation of the left ventricular free-wall and oriented major vectors caudad and dorsad, as opposed to their craniad and dorsad orientation in the control state. Peak magnitude of QRS portion of the spatial magnitude electrocardiogram increased markedly, and duration of QRS doubled. Epicardium in the ischemic zone depolarized tardily, whereas in the control state, epicardium from all areas on the left ventricle was activated early during QRS and nearly simultaneously.

Morphologic features of the vectorcardiographic T loop in arteriosclerotic heart disease

The vectorcardiographic appearance of the highly magnified T loop of 80 patients with arteriosclerotic heart disease was studied and compared with that of 20 normal subjects. The severity of the arteriosclerotic heart disease was evaluated by coronary arteriography.The following indicators were found to be characteristic of the subjects with arteriosclerotic heart disease and were considered to be abnormal: 1.1. The T loop angle was outside the normal range in about half the cases, and was projected in a direction other than anterior, inferior and to the left in 50 per cent.2.2. A wide QRS-T angle was found in the frontal and horizontal planes in about half of the cases.3.3. A length/width ratio of 3.0 or less, considered abnormal in our study, was found in 39 per cent of the cases.4.4. Open T loops were found in the frontal plane in 36 per cent, in the horizontal plane in 47 per cent, and in the sagittal plane in 35 per cent.5.5. Terminal delay in the inscription of the T loop was considered abnormal and was noted in 41 per cent of the cases of arteriosclerotic heart disease.The rotation of the T loop and its relation to the rotation of the QRS loop appeared to have no significance in the diagnosis of arteriosclerotic heart disease.

A Geometrical Model of Successive Stages in Excitation of the Human Heart; its Value as a Link between Excitation and Clinical Vectorcardiography

A geometrical model of successive stages of cardiac excitation in man, based on the anatomy of a normal heart and on certain simplifying assumptions, was devised. Its value for a better understanding of the spread of excitation and the relation of the latter to the shape of the QRS loop in the vectorcardiogram is discussed.

Serial vectorcardiograms with the Frank system in patients with acute inferior wall myocardial infarction

Vectorcardiographic criteria for the diagnosis of acute inferior wall myocardial infarction is described based on the study of serial vectorcardiograms taken in 10 consecutive cases. The abnormalities of the QRS loop were confined to the initial depolarization forces and consisted in the superior orientation, clockwise inscription and abnormal magnitude of the 25 msec, in the frontal plane with superior displacement of the maximal QRS vector in the same plane. These abnormalities occur as early as 24 hours after the onset of clinical symptoms and persisted throughout the subacute stage. Reverse rotation of the QRS loop in the sagittal plane in the presence of clockwise rotation in the frontal plane was not seen with concomitant anterior wall infarction. It is suggested that this change in rotation could be the result of left ventricular enlargement or to conduction defect. It is concluded that vectorcardiography is a useful adjunct to electrocardiography in the diagnosis of acute inferior wall infarction.

Quantitative Analysis of Vectorcardiogram in Right Ventricular Overloading

Quantitative analysis was made to clarify the ventorcardiographic findings characteristic of mild to moderate right ventricular systolic and diastolic overloadings. Materials and Methods Twenty-two cases of ostium secundum type of atrial septal defect (ASD) proved by cardiac catheterization and/or surgery and clinically typical pure mitral stenosis (MS) were subjected to the present study. The three planar projections of VCG were photographed on 60×60 mm X ray films simultaneously by three channel vectorcardiograph using the Frank system. Three scalar ECG of the Frank system were recorded simultaneously by the paper speed of 100 mm per second using three elements direct-writing electrocardiograph. Parameters of morphological observations and quantitative analysis used in this study are as follows: 1. Directions of inscription of QRS and T loops. 2. Directions of initial and terminal QRS vectors. 3. Length, width and length/width ratio of QRS loop. 4. Maximum QRS vector time, QRS duration and incidence of terminal delay. 5. Magnitudes and directions of maximum QRS and T vectors. 6. QRS-T angle and QRS/T ratio. 7. Magnitudes and directions of instantaneous QRS vectors. 8. Spatial mean linear, angular and areal velocities of QRS loop. 9. Spatial circumference, angle, area and thickness of QRS loop. These were statistically compared with those of normal young men. Results and Discussions 1. Directions of inscription of QRS and T loops. Incidence of clockwise inscription of horizontal QRS loop was higher in ASD than in MS. Bizarre configuration of QRS loop in left sagittal plane was frequently observed in ASD, and was considered as one of the characteristic findings in diastolic overloading of the right ventricle. Direction of inscription of T loop changed earlier than that of QRS loop.

A constructued method of the QRS loop in right ventricular hypertrophy.

In order to investigate the cause of the QRS loop change in right ventricular hypertrophy, the present authors have employed their constructed method of the QRS loop. 1) increasing the vectors of the right ventricle including the right side of the septum and 2) prolongation of depolarization process in the right ventricle are required to construct the QRS loops in systolic overload of the ventricle. Next, 1) increasing the vectors of the right ventricle (the increasing ratio of the vectors in the anterior and lateral wall of the right ventricle are larger than that in the posterior wall) and 2) delay of the start of the depolarization process in the right ventricle are necessary in diastolic overload of the right ventricle. Then, the reason of difference of the QRS loops in systolic and diastolic overload is discussed.

Quantitative analysis of vectorcardiograms of the left ventricular overloading

The present paper is concerned with qualitative and quantitative analysis of changes in vectorcardiogram (VCG) characteristic of the systolic and diastolic overloading of the left ventricle, which may, be more markedly manifested in essential hypertension and aortic regurgitation respectively. The results obtained are as follows : Materials and Methods 120 patients with essential hypertension (EH group) and 24 patients with aortic regurgitation (AI group), and 73 normal adults (control group) were subjected to this investigation. Spatial VCG with the Frank system in three planar projections were simultaneously photo-graphed, and three scalar ECG as well as conventional ECG of 12 leads were also coincidentally recorded. For precise analysis of the time factor, vector loops enlarged 15 times through a photographic projector were traced on a paper. Based upon these documents, X, Y and Z components in each instantaneous QRS vector, spatial maximum QRS and T vector were measured. The variables thus obtained were analyticogeometrically analyzed by means of the digital computer "OKITAC 5090 H", managed at the Computation Center of Kyushu University. Results and Discussions 2. 1. Directions of the initlal and terminal QRS vector (Table I). As shown in Table I, the initial QRS vector are frequently directed anterosuperiorly to the right, comprising 60 per cent of the EH and 58 per cent of the AI group. Only one case among the AI group showed the left and posterosuperior direction. The terminal QRS vector is mostly directed to the right posteriorly in the control group (85%). The left and posterosuperior direction in the terminal QRS vector was seen in 13.3 per cent of the control group, whereas in 26.6 and 50 per cent of the EH and AI groups respectively. 2. 2. Rotating directions (Table II). Counterclockwise rotation (CCW) of the frontal QRS loop was observed in 21.7 per cnt of the EH, showing a tendency similar to the control group (20.5%). On the other hand, the incidence of clockwise rotation (CW) was significantly smaller among the EH group (8.3%). CCW rotation of the frontal QRS loop was observed in 66.7 per cnt of the AI group. CW rotation of the horizontal QRS loop was observed in 16.7 per cnt of the AI group, while any sign of CW rotation is not observable in the EH and control groups. CW rotation of the horizontal and sagittal T loop was observed in 80 per cnt of the EH and AI groups.

The initial 0.04 second polar vector of the QRS loop as an aid in the detection of a myocardial infarction.

The initial 0.04 second polar vector of the QRS loop as an aid in the detection of a myocardial infarction.

A use of Adaline as an automatic method for interpretation of the electrocardiogram and the vectorcardiogram.

A learning machine "adaline neuron" was employed for automatic diagnosis of the vectorcardiogram and the electrocardiogram. The frontal circle and the horizontal circle were divided into 480 meshes. The features were expressed by a binary digit, whether the vector loops passed through each mesh or not. In a part of the trials, 5 sets of binary digits were applied in addition to QRS duration and direction of inscription of QRS loops and T loops. In this trial a total of 490 meshes were used. Vectorcardiograms were taken by FRANK'S method in 235 cases. Several methods of adaline usage were tried. The best result was obtained so far by successive dichotomies based on the principle of the logical decision tree. First the normal patterns and the abnormal patterns were divided. The correct ratio was 96.5% when the 490 meshes were employed, cases of an output value within ±10 units being regarded as undecided. Next the abnormal cases were divided into two groups depending on whether the QRS duration was more than 0.12 seconds or less. The group of cases with a QRS duration of less than 0.12 seconds was divided into right ventricular hypertrophy and others. The correct ratio was 98.6%. The remaining cases were divided into left ventricular hypertrophy and myocardial infarction, the correct ratio being 88.8%. The group of cases with a QRS duration of more than 0.12 seconds was easily divided into complete left and right bundle branch block in all cases. Here the number of meshes could be decreased to 59 meshes without changing the accuracy appreciably. This attempt showed that the application of the adaline for automatic diagnosis of the vectorcardiogram and the electrocardiogram is promising.

Spatial magnitude electrocardiogram in normal men.

Spatial magnitude electrocardiogram is a record of spatial magnitudes of cardiac vectors which vary spatially as a function of time on a linear time scale. Spatial magnitude electrocardiograms were recorded in seventy normal men. QRS waves of normal spatial magnitude electrocardiograms were classified in five definite patterns. The configurations of spatial magnitude electrocardiograms were determined by the spatial configurations of QRS loops. The characteristics of normal spatial magnitude electrocardiograms were investigated quantitatively as well as qualitatively by introducing various parameters for measurements. Clinical usefulness of this new electrocardiographic approach was discussed.

Study on the vectorcardiogram in hypertensive patients

Hypertension is noted for its very slow but long clinical course. It is important to predict the case prior to the development of organic changes in the cardiovascular system. The prognosis of hypertension is considered poor when the case is complicated with cardiac disturbances. It is well known that hypertension frequently causes left ventricular hypertrophy as a result of hemodynamic overloading. Many reports have been made on the electrocardiographic findings in left ventricular hypertrophy in hypertensives. However, it is one of the most difficult diagnostic procedures to predict left ventricular hypertrophy on the basis of electrocardiogram. It seems that many criteria proposed for left ventricular hypertrophy so far reported have failed to reach any agreement. The present study was made on possible relationship between vectorcardiographic findings and severity in hypertensives. Material and Method One-hundred and thirty-six cases with essential hypertension were studied. Forty cases without cardiovascular disorders were studied a controls. The subjects studied were divided into 4 groups, from I to IV, according to their severity. The chest was X rayed; the conventional twelve lead electrocardiogram and the vectorcardiogram on Frank's system were recorded at the same time. On the vectorcardiogram, the pattern of QRS loop in horizontal plane, direction and magnitude of maximal QRS vector and maximal T vector, leftward, rightward, anterior, posterior, superior and inferior diameter of QRS loop, width / length ratio of T loop, QRS-T angle and magnitude of maximal T vector/magnitude of maximal QRS vector ratio, etc. were discussed in reference to the grade of severity of hypertension. Result Regarding the pattern of QRS loop in horizontal plane and the grade of severity, Normal type was more frequently found in mild cases (Grade I), than other groups (Grade II to IV), and Left ventricular Hypertrophic type was frequently found in more advanced cases (Grade III to IV). There was no Normal type in severe and progressive cases (Grade III and IV). The magnitude of maximal QRS vector both in frontal and horizontal planes was correlated with the grade of severity and was greater in severe cases.

Vector loops from normal children recorded with the HCB spatial lead system

The HCB spatial lead system is described. It employs the Burger coefficients developed from a heterogeneously conductive model and human cardiac electrical activities. All other biophysically founded spatial lead systems developed in this country are from homogeneously conductive models. The electrode placement of the HCB system is the same as with the equilateral tetrahedron, the most convenient among all lead systems, but the former rests on a biophysical foundation. A preliminary study of the HCB system with normal children shows that in the horizontal plane the QRS loops are very similar in configuration and orientation and the angles formed by maximum QRS and T vectors are very narrow. With improved torso models more accurate coefficients can be determined at present. Whether the new coefficients, though desirable experimentally, will improve the diagnostic value of clinical vectorcardiography is uncertain.

The ventricular gradient and the vectorcardiographic T loop in left ventricular hypertrophy

Summary In ninety-eight case with hypertension or aortic insufficiency and 60 normal persons the spatial ventricular gradient (G) and the direction of inscription of the QRS and T loops were determined, using the Frank lead system. The angular range was measured as a quantitative estimate of the direction of inscription (sense of rotation) of the loops. The ratio of the G magnitude to the QRS magnitude was found to be a good parameter for the elevation of the T loop changes. The direction of inscription of the horizontal T loop was found to be related to the QRS-T angle as well as to the shape of the QRS loop. These findings are explained on the basis of possible patterns of myocardial recovery.

Phosphorus Poisoning Simulating Acute Myocardial Infarction

Elemental yellow phosphorus marketed in collapsible tubes as a rat poison and an insecticide, is an extremely toxic substance readily available in drug, grocery, and hardware stores as Electric Paste (net weight 62.5 gm, 2.5% [1.57 gm] elemental yellow phosphorus by weight). In a total of 115 patients attempting suicide with Electric Paste, Diaz-Rivera et al^1,2recorded 35 (30%) deaths. Acute cardiovascular collapse accounted for the majority of the deaths. The heart is one of many organs affected by phosphorus, and several electrocardiographic abnormalities have been reported.^1-4However, changes diagnostic of or consistent with myocardial infarction have not been described. Recently we treated a patient with acute phosphorus poisoning whose electrocardiogram disclosed changes ordinarily interpreted as evidence of acute infarction of the anterolateral wall of the left ventricle. Rapid resolution and, ultimately, disappearance of the abnormal electrocardiographic pattern for myocardial infarct occurred within two weeks. At that time, a vectorcardiogram failed to demonstrate any deformation of the spatial QRS loop suggestive of myocardial infarction.

Transposition of the great vessels with hypoplasia of the right ventricle.

Eight cases are reported in which complete transposition of the great vessels was associated with varying degrees of hypoplasia of the right ventricle. In three, the correct diagnosis was suspected on the basis of certain electrovectorcardiographic findings and confirmed by selective angiography. Quantitative analysis of ventricular volumes and valve circumferences demonstrated that these cases represent a distinct pathological entity. The diagnosis of complete transposition with hypoplastic right ventricle may be suggested by electrocardiographic evidence of left ventricular hypertrophy, relative absence of right ventricular QRS vectors, and leftward axis for age. The vectorcardiogram reveals a counterclockwise QRS loop in the horizontal plane, situated to the left and posteriorly. These findings occur infrequently in the young infant with complete transposition. The presence of a hypoplastic right ventricle is confirmed by angiography, which demonstrates a small right ventricular chamber located centrally in the cardiac silhouette, not extending beyond the left border of the thoracic spine.

The T loop in right bundle branch block: A vectorcardiographic study of 82 cases

ectorcardiographic studies of QRS loops in right bundle branch block (RBBB) have been reported by many authors, and the classic abnormalities are discussed in texts and symposium proceedings.l-6 The T loop in RBBB has received scant attention thus far, except for Chou and associates’g who reported the incidence of abnormal T loop wideness in 10 per cent of RBBB cases. The rotational characteristics of T loops in RBBB, as encountered in ischemic heart disease, in right ventricular enlargement, and in healthy persons have not been explored. The purpose of this investigation was to survey T-loop characteristics in a series of patients whose RBBB was of diverse etiology.

The Vectorcardiographic Findings in Patients with Artificial Pacemakers

The vectorcardiographic findings in 20 cases with artificial pacemakers (intravenous or implanted) are presented. In patients with implanted pacemakers, the vectorcardiogram displays two major patterns: (a) the main QRS loop is directed to the right, anteriorly and inferiorly; (b) the QRS loop is located mainly in the right posterosuperior quadrant. There is marked displacement of the J point in several cases. In the patient with intravenous pacemakers, the vectorcardiographic pattern resembles that found in LBBB. The abnormal depolarization of the myocardium as a cause of this vectorcardiographic pattern is stressed. These data contribute to a better understanding of aberrant conduction because the origin of the impulse is known.

The frontal plane vectorcardiogram in old inferior myocardial infarction. Criteria for diagnosis and electrocardiographic correlation.

The early part of the frontal plane QRS loop (Frank lead system) was analyzed in 100 consecutive patients with an old inferior myocardial infarction. In order to be included in this study, all cases had to fulfill, at some time, Myers' classical ECG criteria for the diagnosis. The vectorcardiogram was made months to years after the patient's original acute episode. Several scalar and planar parameters, pertaining to these frontal plane early QRS vectors, were analyzed. As a result of this analysis and in order to prevent overlap with values found in 315 normal control subjects, VCG criteria, based on the interrelationships of several of these parameters, were proposed for the diagnosis of old inferior myocardial infarction. Pitfalls in the use of only scalar or planar analyses were pointed out. In 90 of the 100 cases the diagnosis was made on the basis of the proposed VCG criteria. However, the ECG made at the same time fulfilled Myers' or Goldberger's classical criteria in only 42 of the 100 cases. All cases diagnosed from the ECG were also diagnosed from the VCG.