[Thoracic circle in the electrical exploration of the heart].
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
G A Medrano
Publications and source records attributed to G A Medrano.
[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↗
The rational approach to the electrical exploration of the heart.
A rational approach is inevitable in any scientific activity. Such an approach is opposed not only to irrationality, at all inadmissible in scientific thinking, but also to empiric reasoning. Many years ago, Sodi Pallares introduced the rational method in the electrical exploration of the heart based on experimental findings obtained in his laboratory. This method has progressively been accepted and used with good results for diagnoses and has led to logical therapeutic inferences. To confirm the results from the logical interpretation of electrical tracings, we present some examples of its application in three fields: arrhythmias, myocardial infarction, and left ventricular hypertrophy. In the studied cases--two with tachycardia, one with a posterior infarct, and two with left ventricular hypertrophy--a very satisfactory correlation has been observed between the electrical exploration findings and those obtained through direct examination of the heart. It is desirable, and even profitable, to analyze in this way the electrical tracings to get as close as possible to reality, rejecting the stereotyped aspects of a simple routine exploration, which often induce errors and lead to some fallacious asseverations.
Electrocardiography↗
[Usefulness of vector analysis of the electrocardiogram].
An electrocardiogram corresponding to an obese, hypertensive woman 52 years old, is presented. It shows a left bundle branch block of advanced degree and the AQRSF at 70 degrees. In this case, the key of the electrocardiographic diagnosis is that the second vector originated by depolarization of the lower left septal mass is oriented downward, which is unusual in the presence of left bundle branch block. This fact may be due to a marked clockwise rotation. Therefore, it is possible that right ventricle pathologic conditions be associated to those involving the left ventricle. Cardiopulmonary tests determined the existence of a chronic pulmonary emphysema. Furthermore the study of this case shows the usefulness of vectorcardiographic exploration in clinical practice.
Electrocardiography↗
[Rational electrovectorcardiography].
The mental process of electrocardiographists to adjust the electrocardiogram's or vectorcardiogram's interpretation with the sequence of myocardial depolarization and repolarization can be accomplished in two ways. The first one is through vectorial analysis and the second concerns the analysis of unipolar morphologies. The most suitable is to follow both ways. The first procedure constitutes the classic method accepted since Einthoven's time and refers to the vectorial representation of the electrical charges of the heart. This representation approaches the electrical moment of a unique dipole, when cardiac exploration is performed at the smallest adequate distance. This allows to establish the spatial position of the instantaneous vectors, or of the mean vector, by using different leads. The study of unipolar morphologies permits to know the distribution of the mentioned charges in the conducting medium. The adjustment of the electrical charges depends on the location of the wave fronts. These charges produce potential variations in the physical sense--Gaussian type--at the epicardial surface and also at any point of the conducting medium surrounding the heart as far as the skin. This procedure requires the use of Poisson's integral, based on the principle of Helmholtz' electromotive surface. Thereafter, it is mandatory to perform another adjustment for the results of both procedures and to scrutinize the inner cellular metabolic process, which can explain the behavior of the observed electrical phenomena and suggest the adequate treatment.
Humans↗
[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 atrial enlargements].
Rational interpretation of changes of the P loop due to atrial enlargements must to rely on the magnitude and spatial orientation of main resultant vectors of the activation sequence of the atria. Under normal conditions, these vectors give rise to a mean vector oriented to the left downward and discretely forward with respect to their point of origin. In the presence of right atrial enlargement, the manifestation of the first vector of atrial depolarization, oriented downward and forward, is increased. This one moves in the same direction as the mean vector of atrial depolarization, originating an elongated P loop of more than 100 mcv in the three planes. Nevertheless, in the horizontal plane, increase of the P loop voltage predominates when hypertrophy exists, while augmentation of its area predominates when dilatation exists. In left atrial enlargement, the manifestation of the second vector of atrial depolarization, oriented to the left and backward, is augmented, and it moves in the same direction as the mean vector of atrial depolarization. For this, the PF loop acquires a characteristic aspect of a boxing glove, an the PH loop becomes diphasic, with its posterior area more or less prominent, or with a typical figure-eight conformation. If a biatrial enlargement is present, the manifestation of both the main resultant vectors of atrial depolarization is accentuated. Therefore the voltage of the diphasic P loop increases. Moreover the Ps loop has a triangular configuration, with its base of 30 msc or more, located below its point of origin. Generally disturbances of interatrial and intraatrial conduction coexist owing to myocardial damage.
Cardiomegaly↗
[Experimental subendocardial postero-inferior infarctions].
In 30 mongrel dog hearts, epicardial and thoracic unipolar records were obtained after myocardial damage was produced by infiltration of 96% alcohol in the postero-inferior free left ventricular wall. Necrosis was transmural in 5 cases, subendocardial in 11 and intramural in 10. In 4 dogs, intramural unipolar and bipolar leads were recorded in order to determine the electrical subendocardium and its relation to potentials of Purkinje's fibres. At the end of each experiment, left posterior subdivision block (LPSB) was provoked. In 90% of the cases, direct epicardial records were QS in transmural infarction, qrS or less frequently QRS in subendocardial ones, and rS or qRS in the presence of intramural necrosis. In several cases myocardial necrosis was located in the middle third instead of the inferior third, but the direct registries were similar. Nevertheless the surface leads (II, III and aVF) did not show abnormal Q waves or greater voltage of Q and S, but there were RS complexes in V1 and V2. In 80% of the cases, transmural necrosis of inferior third was manifested by QS complexes and subendocardial necrosis by rS or qRS complexes with increased Q and S waves and reduced R waves. LPSB masked the signs of necrosis. There is no justification for speaking of myocardial infarction with or without abnormal Q waves, because it does not add more precision. Moreover these expressions can create confusion in cases of middle or high posterior myocardial necrosis, revealed by RS complexes in V1 and V2.
Animals↗
[Electrical aspects of experimental diastolic and mixed ventricular overload].
Hemodynamic and electrical adaptation of ventricular myocardium to progressive diastolic and combined overloads was studied in mongrel dogs weighing between 15 and 20 Kg, anesthetized with intraperitoneal sodium pentobarbital (35 mg/Kg). Unipolar epicardial and intracavitary records as well as corresponding ventricular pressure curves were obtained every 30 mn after infusion was begun. The systolic arterial pressure was followed continuously by a mercury manometer. Right ventricular overload was produced by means of continuous venous infusion of saline solution in a group of 115 dogs with open pericardium (Series A) and in another of 45 dogs with intact pericardium (Series B). In Series A, right proximal and peripheral blocks were present in all the cases, beginning at 180 mn of infusion. In Series B, at 210 mn blocks were not present in 18 dogs (40%), and right peripheral blocks were present in 27 (60%). Left ventricular overload was obtained through continuous infusion of saline serum into left atria of 31 dogs with open pericardium (Series A1) and of another 50 with intact pericardium (Series B1). Only peripheral left blocks appeared in both series. Between 240 and 300 mn of infusion, the percentage of surviving animals was greater in Series B1, with a statistically significant difference at 270 and 300 mn. The pericardium seems to hinder the adaptation of right ventricular myocardium to the overloads evaluated, while it seems to help the response of the left ventricular myocardium to diastolic and combined overload.
Animals↗
[Electrovectorcardiographic aspects of systolic and diastolic overloads of the left ventricle].
Electrovectorcardiographic features of the ventricular depolarization and repolarization related to hemodynamic conditions were studied in typical cases of left ventricular systolic and diastolic overloads. Electrovectorcardiographic exploration was effected prospectively in 70 subjects with aortic coarctation (52 men and 18 women) and in 90 with patent ductus arteriosus (18 men and 72 women). Fifty-five subjects of the series with systolic overload (A) and sixty-five with diastolic overload (B) underwent surgical treatment. In all cases, high fidelity tracings were obtained by means of a VR-6 polygraph: standard leads, unipolar limb leads, thoracic and precordial unipolar leads from V7R to V7 or V8, high abdominal leads MD, ME, MI and, when it was possible, the corresponding intraventricular unipolar leads. Vectorcardiographic curves were recorded in three planes by Grishman's cube method and photographed using the polaroid system. In both series, ventricular conduction disturbances of proximal or peripheral types were observed. These seem to be independent of hemodynamic conditions. In the presence of aortic coarctation as well as of patent ductus arteriosus, the Q-Tc interval can be prolonged in all leads, probably owing to electrolytic disorders, or in left leads only as a reflection of elevated telediastolic pressure in the ipsilateral ventricle.
Adolescent↗
[Impact of experimental infarction of the right ventricle on P, Ta and QTa readings].
Right atrial (RA) damage was produced by subepicardial infiltration with 96 percent alcohol in 18 dogs' hearts. Anterolateral, right appendage and right side of interauricular band were injected. 19 surface readings, including right thoracic, abdominal (MD, ME, MI), and five direct atrial unipolar records were obtained using VR6 photographic paper and a direct-writing machine (Sanborn 150) with 4 channels at 50 and 100 mm/sec speed. Records were made in control conditions and immediately after infiltration as well as 120 minutes later. Premature atrial contractions and A-V block were provoked in order to measure, precisely, the QTa duration and its termination in the ventricular ST. Rate slowing, slight broadening of P and P-R as well and in 4 cases low right atrial rhythm were observed. Significant changes in the right thoracic leads and even in the V4-V5 leads, as well as in RA unipolars, were also demonstrated, that is: P-R segment elevation (injury vector pointing toward the RA), Qr or Wp waves (necrosis vector away from RA). Nevertheless, leads II, III and a VF showed q o w p waves with less significant Ta changes. Ischemic vector went away RA pointing toward the left one, magnifying the protuberance or irregularities on ventricular ST. The QTac was prolonged beyond VM + 0.04, with the greater one in RA leads. This behaviour was evidenced on premature blocked atrial contractions as well as in A-V block. Similar alterations of P wave can be observed in RA infarction as well in myocarditis.
Animals↗
[Duration of the atrial QT (QTa) under normal conditions and its values in atrial damage].
Atrial QT(QTa) was measured in lead II, in right thoracic leads V4R, V3R and V1 as well as in five direct atrial unipolar leads in 40 dogs. Atrial damage of right or left atrium was provoked by infiltration of 96 degree alcohol in 30 dogs Premature right atrial beats were induced till one was blocked and A-V block was provoked in 10 other normal dogs as well as in those with right atrial damage. Control QTa was observed to include the terminal QRS notch and the proximal irregularity on ventricular ST interval that was better seen in direct leads with sinus rhythm and confirmed later in A-V block and blocked atrial premature beats. It was concluded that normal corrected QTa (QTac) can be obtained by QTac = 0.32 2 square root P-P +/- 0.02. In atrial damage the value increases beyond + 0.04 inclusive + 0.013 with the greater values in the right atrial unipolar. This formula allow us to recognize normal or abnormal QTac duration and to be acquainted that the terminal notch of QRS is produced by the final forces of atrial recoviry in some cases as well as to determine the position of vulnerable atrial period on the ST ventricular segment with and without atrial damage.
Animals↗
[Changes in ventricular depolarization and repolarization in 116 cases of surgically treated interauricular communication].
The postoperative changes of ventricular depolarization and repolarization were studied in 116 cases of atrial septal defect 3 to 8 years after surgical treatment. High fidelity multiple unipolar registries as well as the vectorcardiographic curves in three planes were obtained. Before surgery there were 101 RBBB (87.07% of this series). Of 22 minor degree RBBB, 17 (77.27%) showed no changes, 2 (9.09%) became distal blocks and 3 (13.64%) became intermediate degree RBBB. Of 77 preoperative intermediate degree RBBB, 20 (25.97%) diminished to a minor degree, 1 (1.3%) became a distal block and 2 (2.6%) augmented to an advanced degree. Fifteen distal right blocks (12.93% of the total of cases) persisted postoperatively. Signs of right ventricular enlargement disappeared in all the cases. The right Q-Tc, previously prolonged in 38 cases (32.76% of this series), was normal after surgery. Peaked or negative interpolated T waves disappeared in right precordial and transitional leads. The electrocardiographic features of ventricular repolarization seem to reflect hemodynamic improvement better than those of depolarization. The electrocardiogram permits classification of the disturbances of right ventricular conduction, while the vectorcardiogram shows variations in dimensions of the right ventricle.
Adolescent↗
[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↗