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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 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 vectorcardiogram gives valuable information on the sequence of ventricular activation.

Acute anoxia was produced in 80 dogs under anesthesia with sodium pentobarbital. Respiration was maintained with a Palmer's pump through an endotracheal tube. The anoxia was produced by stopping the pump and occluding the endotracheal tube. Polarizing solution (glucose-potassium-insulin) was perfused in 40 of the animals, starting three hours prior to the anoxia. The remaining 40 dogs comprised the control group. Peripheral electrocardiograms, as well as electroencephalograms, were simultaneously recorded before and during the period of anoxia. Recordings were continuously obtained until no more than one ventricular complex in a ten-second period was observed, even though the electrical brain activity had disappeared by this time. Our present experimental work suggests the beneficial effect of polarizing solutions by delaying the anoxic degradation of the electrical phenomenon of the heart and the brain.

Total extirpation of the blocked free ventricular wall in cases of bundle branch block does not modify the general morphology of the tracings and suggests a poor contribution of the wall in the determination of such morphologies. The forces across the interventricular septum in cases of bundle branch block are very important, and they give a satisfactory explanation of the unipolar morphologies.

(1) The Purkinje potentials were registered in different regions of the interventricular septum and the free ventricular walls in the dog heart. (2) A mapping of the distribution of these potentials is presented. (3) Experimental proof that the deflections recorded represent the potentials of the Purkinje tissue is given. (4) The behavior of these potentials in cases of complete and incomplete bundle branch block, as well as with different degrees of A-V block, was studied. A progressively delayed inscription of these potentials was found in respect to the potentials of the bundle of His as well as a progressive approach to the beginning of QRS in Lead III in the blocked side. (5) The behavior of the Purkinje potentials recorded at the interventricular septum after complete bundle branch block speaks in favor of the existence of a physiologic barrier which separates the left and right septal masses.

Experimental work is presented to prove that many extrasystoles, classically diagnosed as ventricular premature beats, are not. Most of them correspond to atrial or nodal extrasystoles with some degree of aberrancy. On the other hand, there are ventricular premature beats with normal QRS duration and supraventricular beats with QRS duration greater than 0.12 second. The differentiation of ventricular and supraventricular premature beats must be established by considering the morphology of the extrasystolic complex as well as the time in the cardiac cycle when the premature beat is recorded. Definitions of ventricular extrasystoles from several recent textbooks are reviewed. A new definition is proposed based on experimental work performed in the dog's heart.