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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 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.

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 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.

In this prospective work eleven pneumopathes patients were studied, ten of them with HAP, which were subjected to effort prove in endless band, in order to know the electrocardiographic alterations presented during the exercise. The VO2 máx was determined simultaneously in four patients. In the four, the value of this parameter was found under the normal value, which showed us a poor increase of the cardiac expense for the demands in the exercise. If the effort proves had not been practiced, this fact could not have been known. Related to the electrocardiographic alterations, cellular diastolic depolarization signs (cellular damage), product of the cellular damage, were found. The mechanics of this cellular damage, as well as the one of the poor increase of cardiac expense, are mentionned in the discussion.

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.

The sequence of ventricular repolarization process is studied in 25 dogs, using unipolar epicardial leads and some distant bipolar leads. It is concluded: 1. The sequence of ventricular repolarization process is from the base to the apex of the heart. 2. Its sense is independent from the activation process. 3. It is demonstrated the nature of the intrinsec deflection of the repolarization process. 4. The duration of the electrical systole is greater in the myocardial fibers of the right ventricle than in the fibers of the left ventricle. 5. The duration of the electrical systole is constant in the myocardial fibers of a blocked ventricle, but is delayed in the same proportion of the activation process. 6. The significance of the biphasic T wave is discussed, in the presence of bundle branch block. 7. Some bases are withdrown for the deductive interpretation of the T wave based upon the ventricular repolarization process.

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.