Right posterior ventricular necrosis. An experimental study.
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Animals↗
Biomedical subjects
G A Medrano
Publications and source records attributed to G A Medrano.
Left anterior hemiblock or inadvertent lead misplacement?
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Diagnostic Errors↗
Experimental bases for diagnosis of left bifascicular and trifascicular block.
It seems to be justified to establish the diagnosis of fascicular blocks, in clinical tracings, on the basis of experimental findings. For this, we produced left bifascicular block as well as trifascicular block in the heart of 20 mongrel dogs. Because of left bifascicular block, the activation process is unequally delayed in high lateral and in posterior aspects of the free left ventricular wall. Nevertheless, it begins at normal time in middle left septal mass via intermediate strands of the left bundle. Consequently, left bifascicular block which resembles intermediate degree left truncular block, is recognizable by unequally delayed onset of intrinsicoid deflection in aVL, aVF and V6 and often by the manifestation of the first septal vector. Vectorcardiographic curves are diphasic and show initial and terminal slurrings. Trifascicular block delays the activation process in both ventricles. For this, the asynchronism between the electromotive forces of ventricles is lessened. The said conduction disturbance can be diagnosed by electrocardiographic and vectorcardiographic features suggesting intermediate degree RBBB as well as left bifascicular block.
Adult↗
[Interpretation of stress-electrocardiography].
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Electrocardiography↗
[Protective effect of glucose-insulin-potassium solutions in myocardial damage caused by emetine].
This study was carried out on 170 dogs. Cardiotoxic effects of doses of 15 mg/kg of emetine hydrochloride were studied in 20 dogs. 20 mg/kg of emetine hydrochloride were administered intravenously over 60 min. to the remaining 150 animals. These dogs were distributed in groups of 25. One group received emetine alone. Phleboclyses with saline serum, glucose-insulin-potassium, glocose-insulin, glucose-potassium and glucose serum alone, respectively, were administered to the other 5 groups during the emetine infusion and cardial contraction and several electrograms were recorded. Mean systolic blood pressure was measured continuously in the femoral artery. Observations covered a 4 hour period. During the infusion of emetine alone, ventricular myocardial contraction and systemic arterial pressure decreased abruptly. Intra-atrial, atrio-ventricular and intraventricular conduction disorders, as weel as primary ventricular repolarization changes, were also observed. At the end of this infusion, the Q-T interval increased 25% and the heart rate decreased 26% of the control values. In the group also receiving glucose-insulin-potassium solution, the fall of the ventricular contraction amplitude was significantly less than in animals given emetine alone. Primary ventricular repolarization changes were less evident. The mortality rate reached only 4 per cent. In conclusion, the doses of emetine hydrochloride employed here have depressive cardiocirculatory effects. Glucose-insulin-potassium solution, administered simultaneously with emetine, seems to have a favorable metabolic effect against the emetine cardiotoxicity. This protective action of the G-I-K solution is superior to that obtained with each component, administered separately, and with saline serum.
Animals↗
[Anatomo-vectorcardiographic correlation in ventricular growth in congenital heart diseases].
Anatomo-vectorcardiographic correlations were studied in 59 cases of congenital heart disease. In the group with interventricular septal defect and pulmonary hypertensión, a statistically significant correlation between the thickness of the free right ventricular wall, at its outflow tract, and the inscription time of the vertex of the S loop, was found. In the group of Fallot's tetralogy, the segmentary hypertrophy of the right ventricle, which is the most frequent, explains very well the terminal portion of frontal and sagittal vectorcardiograms located below the 0 point. In the group with interatrial septal defect and pulmonary hypertension, a statistically significant correlation between the thickness of the antero-lateral superior third of the free right ventricular wall and the inscription time of the vertex of the S loop, was shown. In the group of congenital malformations with repercussion on the left ventricle (interventricular septal defect, patent ductus arteriosus and coarctation of aorta), a statistically significant correlation between the anatomical findings of a hypertrophied superior third of this ventricle and the inscription time of the vertex of the R loop, was observed.
Adult↗
[Electro-ventorcardiographic manifestations of ventricular inversion with transposition of great arteries].
Electrocardiograms obtained in two groups of patients with inversion of the ventricles and transposition of the great arteries, were analyzed: group I corresponding in situs solitus and group II to situs inversus. This series comprises 36 cases (29 of group I and 7 of Group II), in which the diagnosis of the main congenital heart disease --ventricular inversion-- and of the associated defects was established by angiocardiography. In 7 cases of group I and in one of group II, the angiocardiographic diagnosis was proved at least in part during open heart surgery. Direct anatomic study was possible in 5 more cases of group I and in 2 more of group II. Each group comprises two subgroups: A, without RBBB, and B, with RBBB of different degrees. Group I consists of 11 cases of subgroup A and 18 of subgroup B. In group II there were 2 cases of subgroup A and 5 of subgroup B. Vectorcardiograms were obtained following Grishman's method in 17 cases of group I (8 of subgroup A and 9 of subgroup B) and in 3 cases of group II (1 of subgroup A and 2 of subgroup B). In 7 cases of group I (5 of subgroup A and 2 of subgroup B), it was possible to record also the vectorcardiographic curves following Frank's method. Electro and vectorcardiographic findings were correlated with hemodynamic data and, in some cases, also with anatomic ones.
Adolescent↗
[Response of experimental ventricular tachycardia to class I anti-arrhythmia agents].
Active ventricular arrhythmias were provoked in damaged dog myocardium to study their response to some antiarrhythmic agents of Vaughan-Williams' class I. Dogs anesthetized with intravenous sodium pentobarbital (30 mg/Kg) were intubated and submitted to artificial ventilation using a Palmer pump. An infarction was produced near the apex of the left ventricle by intramural injection of 1-1.5 ml of phenol, and 30 to 60 min later, minute crystals of aconitine were introduced into the periphery of the infarcted area. Once ventricular tachycardia appeared and became stable, corresponding records were obtained and the antiarrhythmic agent to be studied was administered through the superior vena cava over a period of 5 to 15 min. Electrocardiographic tracings were registered at constant intervals in order to detect the recovery and duration of sinus rhythm. The reappearance of arrhythmia was always required in order to consider the action of the medication administered positive. High doses of lidocaine (6 mg/Kg) reestablished transient sinus rhythm in 23% of 35 treated dogs. Fifteen mg/Kg of mexiletine reestablished it in 45% of 22 animals and 2.5 mg/Kg of propafenone restored it in 39% of 18 animals receiving this drug. The positive effect of these antiarrhythmic agents of groups I B and I C consisted essentially in controlling no-rapid tachycardias with the "wave jumping" phenomenon and fusion beats, which may be due to activity of ectopic foci. Very rapid ventricular tachycardia with "wave jumping" generally did not respond to the antiarrhythmic agents tested. These tachycardias may be maintained by reentry or by the intervention of calcium-dependent potentials. Rapid ventricular tachycardias without extensive "wave jumping" also occurred. These were never controlled by the group I B antiarrhythmic agents, although they were sometimes suppressed with propafenone. These tachycardias probably originated near the intraseptal barrier. In few animals, amiodarone of class III was employed with a marked hypotensive effect.
Amiodarone↗
[Vectorcardiographic manifestations of right ventricular enlargement].
The basic criteria for the vectorcardiographic diagnosis of right ventricular enlargement are discussed, in context with the course of myocardial activation. Right ventricular dilatation, secondary to isolated diastolic overloading (atrial septal defect) shows basically different degrees of dextrorotation. The ventricular curve starts to the left on the frontal and horizontal planes, and forward on the last one. Cases with right ventricular hypertrophy, produced by sustained systolic overload, are also evaluated. When the hypertrophy is generalized (pulmonary valvular stenosis), there is an increase in the manifestation of all the resulting vectors of activation of this ventricle: IIs, IIr, and IIIr. As a resultant of these changes, the ventricular curve presents a clockwise rotation in the three planes, and is oriented to the right and forward, with its terminal portions generally located above the E point. When the right ventricular hypertrophy is of the segmentary type, there is an increase of the manifestation of only some of the resulting vectors of the activation of this ventricle. For example, the vector IIr will be increased in cases of tetralogy of Fallot, while the IIIr will be increased in some cases of obstructive chronic pulmonary hypertensive cardiopathy. The T loop, of secondary type, generally opposes the vector IIr on the horizontal plane, and the IIIr on the frontal plane. When an important right ventricular dilatation is associated to a right bundle branch block of intermediate degree, owing to their proximity, the manifestation of the electromotive parietal forces is increased at the expense of the septal ones. This phenomenon produces a characteristic appearance of the SH loop, narrow and with a clockwise rotation.
Adolescent↗
[Vectorcardiographic manifestations of left ventricular and biventricular enlargement].
The basic criteria for the vectorcardiographic diagnosis of left ventricular and biventricular enlargements are discussed on the basis of the myocardial activation sequence. Left ventricular dilatation, secondary to isolated diastolic overloading, increases the manifestation of all the vectors resulting of the activation of this ventricle. These changes reflect the proximity of the left ventricular walls to the exploring electrodes. The vectors above mentioned project themselves as wide ventricular curves with counterclockwise rotation on the three planes. The T loop, of secondary type, is concordant in its orientation with the R loop. Cases with left ventricular hypertrophy, produced by a sustained systolic overloading, are also described. In the presence of global left ventricular hypertrophy without LBBB, the manifestation of all the vectors resulting from the depolarization of this ventricle (I, IIl, IIIl), is increased. This is due to a prolonged duration of the corresponding activation fronts. These vectors are projected on the different segments of the ventricular curves and they show a counterclockwise rotation on the three planes. When LBBB is also present, the first septal vector is not evident. The T loop, of secondary type, opposes the R loop on the frontal and horizontal planes. The presence of left ventricular hypertrophy of the segmentary type, generally increases the manifestation of the vector I, and sometimes, also that of the vector IIIl. When both ventricles are hypertrophied, the electromotive forces of the chamber more severely affected predominate in the vectorcardiographic records.
Cardiomegaly↗
[Vectorcardiographic manifestations of supraventricular ectopic rhythms].
In the presence of low right atrial rhythms, the eight-shaped PF loop is located in the first quadrant, the PH loop is rotating in a counterclockwise direction and PS can rotate in either course. When the rhythm originates in high left atrial regions, PF and PH loop loops can be found in the third quadrant of both planes and should have a clockwise rotation. When the pacemaker is located in low left atrial regions, the PF loop rotates in a counterclockwise direction, or with its branches superposed, and located in the second quadrant; PH is rotating clockwise in the third quadrant; PS with either a clockwise or a counterclockwise rotation, is situated above and slightly ahead of the E point. In the presence of a nodal rhythm, the P loops show a counterclockwise rotation or an eight-shaped configuration. In the absence of atrial enlargements, the PF loop can be seen in the first quadrant and the PH in the first or the fourth quadrant.
Arrhythmias, Cardiac↗
[Vectorcardiographic manifestations of left intraventricular conduction disorders].
Both, the vectorcardiographic changes produced by the various degrees of left bundle branch block and these observed with the different types of left distal block, are described. When a "wave jumping" phenomenon exists, the vectorcardiographic changes are more characteristic in the horizontal plane than in the frontal plane and can be interpreted satisfactorily in basis of the ventricular activation sequence. The normal counterclockwise rotation of the horizontal vectorcardiogram persists in the presence of left bundle branch block of slight and moderate degrees, since the electromotive forces of the free left ventricular wall are still predominant. In the majority of intermediate degree blocks, the middle portion of the RH loop develops with a clockwise rotation and general aspect with a clockwise rotation and the general aspect of the ventricular loop resembles an eight figure. This is due to the electromotive forces originated by the delayed depolarization of the left septal mass that starts to predominate. With advanced degrees of block, the largest portion of the RH loop shows a clockwise rotation, as well as marked notchings and slurrings. The initial anterior portion of the horizontal vectorcardiogram does not disappear, but is situated to the left of the anterior-posterior axis with a counterclockwise rotation (first right septal vector). Otherwise, the direct electrical sign of left distal block emphasized: evidence of delayed activation in a limited zone of the homolateral ventricle. This local delay gives rise to an asynchronism of the activation phenomenon between the upper and lower regions of the ventricle. The diagnosis of left bifascicular block is based essentially on the evidence of unequal delay of the activation sequence in the basal regions and in the inferior ones of the homolateral ventricle and also on the frequent persistence of the first left septal vector.
Adult↗
[Vectorcardiogram in experimental infarct of the right posterior ventricular wall].
In 20 dogs a chemical necrosis was produced by infiltration of 80% phenol solution within the posterior right ventricular wall and the neighboring interventricular septum. Vectorcardiographic loops were obtained by the cube system in vertical and horizontal heart positions under control conditions, 90 minutes after the necrosis was produced and also after RBB was severed. In 15 dogs the RBB was injured after the necrosis was produced and in 5 previously. In all dogs direct unipolar leads (epicardial and intraventricular), thoracic and abdominal unipolar leads (MD, ME, MI) as well as standard leads were also obtained following the experimental protocol outlined above. Analysis of the changes caused by necrosis in the location rotation and voltage of the initial, intermediate and preterminal portions of the vectorcardiographic curve in the three planes (F, H and left S) permits the formulation of the following conclusions: 1) The most significant alterations were observed in the frontal and sagital planes, particularly in RF and RS loops. In most of the cases, RF and RS loops were displaced upwardly, to the left on the frontal view and slightly anterior on the sagital. The rotation changed to counterclockwise direction on the frontal view and to clockwise on the sagittal one. In a few cases, the clockwise rotation of RF loop was conserved but it was displaced above the mean value of RF curl in horizontal hearts (+ 3 degrees 30'). 2. RH loop shifted posteriorly in both vertical and horizontal heart positions. The area enclosed by centripetal anterior branch RH loop was reduced and its apex was frequently delayed by 3 msec. 3) In presence of RBBB, the alterations described above on the frontal and sagittal views were conserved in both heart positions. The only distinct behaviour was observed in the horizontal loop, in which RH loop is posteriorly located with counterclockwise rotation in the vertical hearts and anteriorly in the horizontal one. Nevertheless, the voltage of R loops increased in both positions when the necrosis was produced after the RBBB. 4) In spite of differences in thickness of the right ventricular wall between dog and man (it is thicker in the dog), we propose that alterations of RF and RS loops could be extrapolated to the human V.C.G. in order to evaluate the involvement of the right ventricle by myocardial necrosis. 5) Similar alterations of RF and RS loops were observed in the presence of necrosis of the left posterior ventricular wall. The only clue to establish a differential diagnosis is based on the characteristics of RH loop, which is more anteriorly displaced with an "8" aspect or clockwise rotation in the presence of left side necrosis. Both VCG and ECG appear to be helpful on the topographic diagnosis and evaluation of injured myocardium in the right ventricle.
Animals↗
[About vectorcardiographic examination].
The clinical importance of the spatial exploration of the cardiac electrical phenomenon (vectorcardiography), which is a very useful integration of the analytical and limited electrical exploration (electrocardiography), is outlined here. Reasons inducing the mexican school to prefer the Grishman's cube method for the vectorcardiographic recordings of other more elaborate and complex systems, are explained. The former reflects in a more reliable way the sequence of myocardial depolarization and repolarization. Morphological and chronological aspects characteristic of the normal vectorcardiogram in the frontal, horizontal and sagittal planes, are described. Additionally some typical examples corresponding to the three main electrical heart positions are presented. The vertical position is frequent in children and longilineal persons, the intermediate position is common in adults and the horizontal one is observed in age people and brevilineal persons. Some vectorcardiographic aspects typical of myocardial necrosis, injury and ischemia are discussed, underlining the importance of the complementary elements given by vectorcardiography.
Female↗
[Effect of isoptin chlorhydrate on the sino-auriculo-ventricular conduction in the heart of the dog].
The effects of Isoptin chlorhidrate (Verapamil) on sino-auriculo-ventricular conduction and automatism were studied on the heart in situ of 13 dogs. In three of them the drug was associated with intermittent intravenous drip of succinylcholine infusión (2 ml in 500 ml 5% dextrose solution). The drug was administered intravenously in 2 minutes (10 mg). In a first step, the action was followed during 45 minutes. In a second step, a second dosis (10 mgr) was administered 45 minutes after the first one. Proximal bipolar leads in the sinoauricular node, His bundle and Purkinje nets as well as distant bipolars leads between the ostium of the superior vena cava and left atrium or lead II, were recorded. Grass's preamplifiers and a Dumont Dual beam oscilloscope with two electronic switches were used for recording. Automatism of the sinus as well as of the His-Purkinje specific pathway was depressed. A significant prolongation of conduction time in A--V node was manifested by increased duration of P--R and A--H intervals. The sinoauricular as well as the Purkinje-muscle conduction were also slightly prolonged. An accumulation of the drug was demonstrated (a second dosis administered 45 minutes after the first one) by an accentuation of A--V block (second degree) and accentuated bradycardia. No escape rhythms were observed and circulation was maintained by mechanical stimulation of the ventricles. The latter effects were more accentuated in dogs in which an intermittent succinylcholine solution drip was administered.
Animals↗
[Fascicular and bundle branch blocks in myocardial infarction (author's transl)].
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Bundle-Branch Block↗
[The electrocardiogram of the normal child].
The EKG findings of 202 normal children, aged 1 month to 10 years were reviewed in order to determine criteria for diagnosis of ventricular hypertrophy. QRS voltage in right and left precordial leads are very variable and do not constitute adequate criteria for the diagnosis of ventricular hypertrophy the same is true with QRS duration, which increases progressively from 50 to 60 msec from the first to the fourth year of life, and to 70 msec over that age. The values found are smaller than those previously reported in the literature. Measurement of initial intrinsicoid deflection time in leads VI, aVF and V6 apparently have important clinical significance. This is a constant finding in normal hearts in lead VI, where deflection time is 18 to 20 msec. Therefore, times above 25 to 30 msec are sugestive of right ventricular hypertrophy when RBBB is not present. Intrinsicoid deflection time in lead V6 in children under one year of age was 20 msec, while between age one and ten it varied between 20 and 31 msec. Such variations show how left ventricular tissue increases after the first years of life, and also that times above 5 msec over those found for any age group are indicative of left ventricular hypertrophy.
Age Factors↗