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A 37-year-old man with Brugada syndrome and dynamic changes of the ST-segment morphology observed after an episode of aborted sudden death is described. On admission, after 3 syncopal episodes during nighttime, his electrocardiogram showed right bundle branch block (RBBB) with a J-point elevation of 0.6 mVin lead V2. Changes observed in the following days included a diminished J-point elevation and intermittent bsaddle-backQtype ofmorphology. During a previous 2-year followup, intermittent, complete, acceleration-dependent RBBB was documented. Right ventricular intracavitary tracings showed an RS pattern with a broad S wave in the unipolar electrogram; the time of onset of intrinsic deflection in this electrogram was 60 milliseconds. To our knowledge, this is the first report of an intracavitary demonstration of complete RBBB in Brugada syndrome. D 2005 Elsevier Inc. All rights reserved.

We report a 37-year-old man with type I second-degree atrioventricular (AV) block (atypical Wenckebach's periodicity) referred to our department for pacemaker implantation because of an episode of syncope. After exhaustive evaluation, including electrophysiological test, in which Wenckebach's cycles with block within the AV node was demonstrated, syncope was considered to be neurally mediated. Head-up tilt testing with sublingual isosorbide dinitrate was positive. The decrease in atrial rate at the beginning of the vasovagal reaction was not immediately accompanied by a depressed AV node conduction. Only at the moment of syncope did incomplete AV block appear. This observation illustrates (1) a neurally mediated origin of syncope in a patient with chronic AV block, and (2) the different time-course responses of the sinus and AV nodes to autonomic tone.

The diagnosis of myocardial ischemia is not confine to the alteration of the RS-T segment and of the T wave. Conduction disorders at any level can be caused by the ischemia itself and contribute to the diagnosis, as well as the ventricular arrhythmias. On the other hand, conduction blocks do not hinder or hide the diagnosis of ischemia. The primary and secondary characteristics of the T wave and RS-T segment are discussed. The relevance of the knowledge of ventricular activation vectors in bundle branch blocks is shown, as well as their alteration in case of associated myocardial infarction. Emphasis is made on the importance of the deductive method in the electrocardiographic interpretation.

The physical basis required to interpret the unipolar morphologies as corresponding to the variations in potential of some portions of the heart are presented (Poisson's integral). Several examples of the utility of these electrocardiographic analyses are discussed. We think that this new form of electrocardiographic interpretation gives a wider range of diagnoses than has been obtained so far through vectorial analysis.

In this study a critical attempt was made to review some of the more recent experimental studies on ventricular activation. A study of the activation of the normal free ventricular wall using the cathode-ray tube confirmed our previous observations. The spread of activation in the subendocardial muscle mass and at least one-half of the thickness of the adjacent free ventricular wall, reaches values of 2,000 or more mm. per sec. In these regions QS complexes are recorded as described by Prinzmetal and collaborators. An attempt to explain this morphology is presented. In left bundle branch block the sequence, sense, and speed of activation in the free left ventricular wall are unchanged as compared to the normal control. The alterations in morphology are mainly due to changes in direction of activation and delay of conduction in the interventricular septum.

Acute cor pulmonale was experimentally produced in dogs by means of mechanical compression of the pulmonary artery. •A. General observations: 1.1.1. There was initial dilation of the right ventricle, especially of the pulmonary conus and, later on, dilation and marked cyanosis of the right auricle. 1.2.2. There was a decrease in the volume of the left ventricle, which appeared as an appendix of the right one. 1.3.3. There was horizontal position of the heart and displacement of the left ventricle upward and backward, the anterior aspect being formed in its greater portion by the right ventricle. 1.4.4. There was collapse of the lungs, which required a considerable increase in the air pressure of the artificial respiration. 1.5.5. Disturbances of rhythm appeared: auricular fibrillation and flutter, mechanical alternancy, and initial and transient bigeminy. 1.6.6. Death was due to ventricular fibrillation, which apparently began in the interventricular sulcus without previous arrhythmia, sometimes with persistency of the normal auricular activity, diastolic ventricular standstill, or atrioventricular block with idioventricular rhythm of decreasing rhythmicity. •B. Electrocardiographic observations: 2.1.1. There appeared a positive shift of RS-T in the pulmonary conus, trabecular zone, and right cavities and a negative shift in the left epicardium and left cavities. The positive shifts of the epicardium and the right cavities appeared and disappeared independently, thus indicating the presence of 2 different lesions, one in the right surface of the interventricular septum and the other in the right wall. 2.2.2. Q appeared in the epicardium of the pulmonary conus; it was explained as due to the fact that the vector of the medial septal activation goes away from the conus as a consequence of the distention of the ejection chamber of the right ventricle. The formation of an obtuse angle between the conus and the septum follows. 2.3.3. In late stages, the right intraventricular tracing is of the rsR type, simultaneous with mirror deflections in the epicardial surface of the conus. This was explained as due to the presence of an intraseptal block, an "inverted Bernheim," and convergence and summation of the septal vector. 2.4.4. Depending on the degree of rotation of the heart on the anteroposterior axis, V F receives left potential with RS-T depressed or right epicardial potential with upright RS-T; and, according to the rotation on the longitudinal axis, V F registers right epicardial potential or right auricular potential with Q wave. The depth of Q in V F is not a differential sign between acute cor pulmonale and posterior myocardial infarction. 2.5.5. Patterns simulating myocardial infarction in right precordial leads may correspond to acute cor pulmonale and depend on right cavity potentials. 2.6.6. In acute cor pulmonale coronary T waves in left precordial leads may appear; sometimes they may be its only manifestation. This may be explained by the disappearance of the gradient of pressure of the coronary circulation. 2.7.7. Positive shifts of the RS-T interval in left lateral leads (V L , V 5 , and V 6 ) are found in left pulmonary infarctions complicated with pleuropericarditis. 2.8.8. Generally, acute cor pulmonale determines a horizontal electrical position, only by exception a vertical one. In this last instance it shows the lesion of ischemia of the right ventricle in I and V L .

The electro-physio-metabolic bases of a new treatment of recent myocardial infarction directed to the cellular level and called "polarizing" are presented. The treatment consists of intravenous infusion of a 1000 ml. of 10 per cent glucose in water solution with added 40 mEq. of KCl and 20 units of regular insulin (G-I-K solution). The effects of this solution were studied both in dogs and in humans. 1.Electrophysiology. (a)Electrocardiographic morphology of the three zones of infarction. (b)Arrhythmias. (c)Activation in the area of the infarction. 2.Electrolytes.The intra- and extracellular K, Na and water was determined in the different zones of the infarction in the control and treated animals. 3.Macro- and microscopic morphology. The macro- and microscopic changes were studied in control and treated dogs after ligation of the anterior descending coronary artery. 4.Clinical study.The clinical and electrocardiographic evolution was compared in 25 control patients and in 25 patients treated with the polarizing solution administered continuously for three to seven days.The polarizing solution has shown favorable results in all instances.It is concluded that this type of treatment may be helpful in various cardiovascular conditions which are associated with aggressive agents. However, much experimentation will be necessary.

Myocardial catecholamine changes were investigated after (i) occlusion of the anterior coronary artery in the dog; and (ii) the effect of propranolol given intravenously (0.1 mg/kg) 30 min after total coronary occlusion. Depletion of catecholamines in the injured zones was similar in the control and the propranolol treated animals. Propranolol caused a small depletion of cardiac noradrenaline and dopamine contents. Electrocardiographic epicardial tracings showed improvement in myocardial conduction in the injured zone on the propranolol treated animals, which could not be related to the catecholamine tissue changes.

Summary The diagnostic difficulties in the recognition of myocardial infarction in the presence of bundle branch block and the Wolff-Parkinson-White syndrome are discussed. However, through a “deductive” approach in the analysis of the electrocardiogram, such difficulties may be eliminated to a great extent. The knowledge of the sequence of cardiac activation in normal and abnormal circumstances as in bundle branch block, “pre-excitation syndrome”, and extrasystolia, is fundamental. To sum up, the “deductive” approach to clinical electrocardiography not only facilitates the general diagnosis but also indicates the limitations in arriving at a precise diagnosis of infarction.

Simultaneous recording of electrograms of the A-V node, bundle of His, right and left branches and the Purkinje tissue was successfully achieved and is herein presented. The speed of the activation wave in some segments of this specific tissue is calculated. A few considerations for future research are also made.

A new approach in the electrocardiographic diagnosis of congenital heart disease is studied. The combination of the determination of ÂQRS in the frontal plane with the knowledge of the electrocardiographic pattern of each congenital heart malformation permits the main diagnosis of the anomaly in a great number of cases.

The right intracavity leads show a great incidence of incomplete or complete right bundle branch block in cases with electrocardiograms very suggestive of right ventricular hypertrophy. In these instances we have found three different forms of rotation of the vectorcardiographic loop in the horizontal plane: clockwise, counterclockwise and mixed rotation. We believe that this is sufficient to state that there is no loop rotation which might be considered as exclusively representative of right bundle branch block.

The electrical consequences of experimental acute myocardial ischemia were studied in 50 dogs. The study was performed through unipolar epicardial leads and at different levels of the conducting system; bundle branch and Purkinje fibers. There is evidence that the block takes place at the Purkinje-muscle union or in the muscle-muscle conduction. In none of the experiments the block appeared in any of the components of the conducting system. Also, there is evidence that with severe ischemia muscle recordings disappeared while the Purkinje potentials remained unchanged, this suggests that conducting system cells are more resistant to hypoxia than the contractile cells. Ventricular arrhythmias usually appeared simultaneously with conduction blocks that favored reentries. Arrhythmias were more frequent when the blocks were more accentuated. Our data demonstrates that the conduction disorder precedes in some instances, the positive RS-T displacement and in others it hides the such displacement. It is concluded that the RS-T displacement, the distal conduction block and arrhythmias are manifestations, at different levels, of partial diastolic depolarization induced by acute myocardial ischemia.

The High-Frequency ECG was studied in 78 patients with systemic arterial hypertension and in 10 normal subjects. The study has shown: a) the P wave is altered initially, according to the disturbances in the myocardial complicance; b) the signs of LVH are mainly: delayed in the appearance of the intrinsecoid deflection, abnormal left direction of vector 3, left electrical systole diminished and counter clockwise rotation; c) the exhaustion fase is represented by increased of the electrical systole, delay in the duration of the intrinsecoid deflection and by primary disturbances of repolarization. The relationships between the ECG and the hymodynamic and metabolic disturbances, are discussed.

On an experimental basis the authors studied the process of repolarization and depolarization in high frequency electrocardiograms of 30 healthy children. The negativity of the T wave in V1 and V2 corresponds with the repolarization of the left ventricle and the positivity with that of the right ventricle. The vectors of repolarization of both ventricles were identified and found to be situated on a horizontal plane. In all tracings the electrical systole of the right ventricle was found to be greater than that of the left ventricle. The number of components of high frequency tracings in the intrinsecoid deflexion was greater on the right ventricle. The authors suggest that the high frequency electrocardiogram is a valuable procedure in clinical investigation.

Several haemodynamic and biochemical parameters were studied in order to explain the diagnostic value of the electrocardiographic abnormalities in partial myocardial diastolic depolarization, in different conditions, as experimental coronary oclussion, adrenalinic effects, tachycardia, hypoxia and shock. It is concluded that the electrocardiographic signs of diastolic depolarization (injury tissue) are: RS-T deplacement, conduction disturbances at bundle, fascicular and muscular levels, as well as ventricular ectopic beats. The experimental findings were correlated with clinical cases showing electrocardiographic signs of ventricular diastolic depolarization, as in myocardial infarct, angina pectoris, hypertensive heart disease, pheocromocitoma and tachycardia. It is concluded that the oxygen volume available at mitochondrial level is diminished, if it is correlated to the metabolic and/or haemodynamic alterations.

The ECG of 37 patients with atrioventricular discordance were studied and divided in two main groups: I) Situs solitus and II) situs inversus, either a) without associated defects or b) with associated defects. It was concluded: 1) The first vector of ventricular activation, oriented in the same sense of that of atrial activation is a fundamental diagnostic sign; 2) The preponderance of anatomical right ventricle, leads to the diagnosis of unassociated defects; 3) The recognition of biventricular hypertrophy obliges to the diagnosis of associated defects; 4) The AQRS deviation and the shortening in duration of the local electrical systole help to recognized the hypertrofied ventricle and its overload; 5) The presence of right bundle branch block is not in relation to the degree of overloading; 6) The primary alterations of ventricular repolarization are univocal signs of myocardial damage.

High frequency electrocardiograms were studied in 19 patients with chronic neumopathies, pulmonary arterial hypertension and respiratory failure in the great majority. Studies were made of: a) the significance of conduction disorders in the right ventricle either at the fasciculary branch or within the mass of the ventricle with regard to the time of appearance and the length of the intrinsicoid deflection and its components. b) The duration of the electrical sistole of each ventricle in relation with hyperatrophy that results in sistolic over loading. c) An attempt was made to correlate the number of high frequency deflections (discontinuity of activity) with the prognosis.