[Effects of intra-arterial Wenckebach's periods on the nodal and intranodal A-V 2:1 and 4:1 (their significance in the electrogenesis of the so-called alternating Wenckebach's periods)]. / Efectos de los períodos de Wenckebach intraauricular sobre el bloqueo A-V 2:1 y 4:1 nodal e infranodal. [Su importancia en la electrogénesis de los llamados períodos de Wenckebach alternantes.]

Intra-atrial Wenckebach patterns coexisting with distal, A-V nodal, and His-Purkinje blocks occurred in eight patients during high atrial stimulation at rapid rates. In two patients with 2:1 St-H block and in two patients with 4:1 St-V block, an increase in the degree of block occurred when the proximal intraatrial Wenckebach cycle was completed with the stimulus which otherwise would have been propagated to the distal levels. However, the degree of block did not increase when the intraatrial Wenckebach terminated in distally blocked stimuli. In one patient progression of 4:1 into 5:1 St-V block was due to the association of intraatrial Wenckebach with alternating 2:1 block at the A-V nodal, and His-Purkinje levels. Contrasting with most reports dealing with the mechanisms of alternating Wenckebach in a single structure, this study permitted the determination of the boundaries between proximal and more distal levels. The electrophysiology of documented two or three level block in different structures has validated previously made assumptions regarding multilevel block in a single structure.

A search for modulation in intermittent ventricular parasystole.

As recently described by Moe et al., parasystolic modulation implies that the ectopic cycle length of a parasystolic focus can be increased or decreased by electrical influences transmitted across the zone of protection. A search for this phenomenon was made in nine patients with intermittent ventricular parasystole resulting from protection only during specific portions of the cycle. All nine patients had a period of relatively early protection affecting the initial 55-67% of the cycle preceding a period of resetting during which the parasystolic focus was discharged and fully recycled. In addition, two patients had a period of relatively late parasystolic protection. Pseudo-resetting (apparent resetting in the surface leads without interruption of activity within the parasystolic focus itself), seen throughout the entire period of late protection in these two patients, and during the relatively refractory period in one patient, was identified because the R waves causing apparent resetting were encompassed by parasystolic-to-parasystolic intervals equalling twice the ectopic cycle length. Our findings indicate that parasystolic modulation did not occur in the type of intermittent ventricular parasystole included in this study. That is, the parasystolic focus was either not affected (not modulated) during specific (early or late) portions of the cycle, or normally reset (discharged and fully recycled, but neither depressed, nor enhanced) in other portions of the cycle. This study does not exclude the occurrence of modulation in other types of parasystole, nor in some automatic nonparasystolic rhythms.

[Exercise tests in pneumopathy patients]. / Pruebas de esfuerzo en pacientes neumopatas.

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.

[Electrocardiographic manifestations of ventricular diastolic depolarization. Clinico-experimental study]. / Las manifestaciones electrocardiográficas de la despolarización diastólica ventricular Estudio clínico-experimental.

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.

His bundle recordings in atrioventricular nodal alternating Wenchebach periods ending in 5:1 atrioventricular block coexisting with paroxysmal atrioventricular nodal block.

Atrioventricular nodal alternating Wenckebach periods ending in 5:1 atrioventricular block occurring during rapid atrial rhythms were explained by postulating the presence of block in three levels of the atrioventricular node. This pattern of conduction occurred in ten of 11 patients who either had received ouabain or verapamil (nine patients) or who had organic atrioventricular nodal disease (two patients). In contrast, this pattern of conduction occurred in only one of eight nonmedicated patients without organic atrioventricular nodal disease. The frequent association of this pattern with paroxysmal, tachycardia-dependent atrioventtricular nodal block suggested a similar, but not necessarily identical, mechanism. In conclusion, atrioventricular nodal alternating Wenckebach periods ending in 5:1 atrioventricular block, as well as paroxysmal atrioventricular nodal block, were only rarely the result of rapid atrial rates per se their occurrence indicating organic or pharmacologic effects on the atrioventricular node. Since both can be produced by carotid sinus pressure, further studies appear to be necessary to determine the role that vagal effects can have in their genesis.

[Electrocardiography of high frequency and pneumopathies]. / La electrocardiografía de alta frecuencia y las neumopatías.

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.

[Direct fetal electrocardiography]. / Electrocardiografía fetal directa.

The advancement in bioelectronics applied to medicine has made possible to carry out, with a high degree of fidelity, the study of the electrical events of the fetal heart. One of the methods in use is the direct or internal method, which offers the advantage of enabling the clear recognition of the different phases of the electrocardiogram, even during labor. An analysis of some parameters of the direct fetal electrocardiogram was carried on in normal term fetuses and whose mothers were in good health, and the parturition was normal. The parameters studied were: heart rate, P-R interval duration, the P wave, the QRS complex, the ventricular activation time, the P-R segment behaviour, intraventricular conduction, and RS-T and T wave changes. The first five items were submitted to statistical analysis for the calculation of the mean value, standard deviation and standard error. The practical application of the results is discussed in terms of deductive approach to the direct fetal electrocardiogram. It is concluded that the method is valuable for the prompt recognition of fetal distress mainly during labor.

[Aerobic functional capacity in normal subjects]. / Estudio de la capacidad funcional aeróbica en sujetos normales

The functional evaluation of a subject may be performed by measurement of the functional aerobic capacity by means of exercise-stress tests. The maximal oxygen consumption (VO2 max) is the best parameter to establish this. The values of VO2 max were determined in twenty-five normal subjects, residents of Mexico City. There were twenty men and five women whose ages ranged between the third and fourth decades of life. A maximal exercise-stress test was performed in a treadmill, with constant inclination and progressive speed increments. Electrocardiogram and blood pressure were monitorized at rest, during exercise and in the recovery period. Four collections of espired gas were obtained, one at rest and three at different levels of exercise. VO2/kg. at rest (the value of one met) was 3.49+/-0.58 ml/kg. min. for the whole group somewhat lower for males (3.37+/-0.53 ml/kg. min.) than for female subjects (3.99+/-0.51 ml/kg. min.). These results are comparable to the ones informed in the literature. VO2 max/kg. was 27.8+/-5.57 ml/kg. min. for the entire group and 28.0+/-5.64 and 27.3+/-5.94 ml/kg. min. for men and women respectively. The values of VO2 max/kg. are definitely lower than the ones obtained from normal subjects in other countries. Considerations are made on the possible causes of this discrepancy. A linear correlation was found between VO2/kg or mets in one side and load imposed, cardiac rate or double product (pulse-pressure) in the other. The different VO2 max/kg. values found in this study as compared to the results obtained from other countries, serve to emphasize the need for each laboratory to establish its own normal values and to construct nomograms for the adquate evaluation of functional aerobic capacity. This, in turn, will permit the accurate and correct prescription of exercise for individual subjects or patients.

[Obstructive pulmonary emphysema. Evolution of various parameters of pulmonary function and its correlation]. / Enfisema pulmonar obstructivo. Evolución de algunos parámetros de la función pulmonar y su correlación

A follow-up study was carried on in a series of 20 patients with chronic obstructive pulmonary disease. The parameters analyzed were forced expiratory volume in the first second (FEV1), maximum voluntary ventilation (MVV), forced expiratory flow (FEF), vital capacity (VC), and diffusing capacity of lung (DL). Considering the importance of the parameter changes observed, each of these parameters were divided in three groups. The period of observation was of two and a half years in 9 patients, and between two years and seven months to four years in 11 patients. The follow-up was characterized by stability of the parameters in cases with the greatest degree of changes, and a definite deterioration of the parameter values in patients with minor degree of basal changes. It was observed an excellent correlation between FEV1 and MVV and FEF. As to CV and DL, the relationship was only good. These findings lead us to believe that MVV and FEF values can be predicted about from the FEV1 results.

[Auricular Q wave in right precordial derivations. New sign of left auricular growth]. / Onda Q auricular en derivaciones precordiales derechas. Nuevo signo de crecimiento auricular izquierdo

The authors present four cases of rheumatic heart disease with severe dilatation of the left atrium which reached the right profile in the radiologic study. An initial negative deflexion of the P-wave (qP) in the right precordial leads was recorder in these cases. The presence of qP was interpreted in view of the atrial activation and the solid angle of the right precordial leads as a variation of potential of the right atrial ceiling and/or of the high interatrial septum, a consequence of the dislocation of the right atrium produced by severe dilatation of the left atrium, demonstrated radiologically in the cases studied. Thee presence of qP is another undoubtably valuable sign for inferring a severe displacement of the left atrium toward the right profile.

Cardiac and pulmonary diseases. A pathophysiologic interelationship.

Left heart diseases, in particular mitral stenosis, are often associated with anatomic and functional alterations of the lung. According to the pulmonary structures involved they could be named chronic secondary intersticial and vascular lung diseases. Congenital heart diseases with pre- or post-tricuspid shunts are also often associated with anatomic and functional alterations of the lung. This condition also constitutes a chronic secondary vascular lung disease (atrial septal defect) or a chronic primary vascular lung disease ( ventricular septal defect, patent ductus arteriosus). Primary lung diseases (interstitial pulmonary fibrosis, pulmonary emphysema, recurrent pulmonary embolism) are often associated with right ventricular hypertrophy with or without dilation, a condition commonly named chronic cor pulmonale. On the whole the interrelationships between heart and lung diseases are as follows: a) anatomic and functional alterations of the lung due to left heart diseases are mediated through pulmonary venous hypertension; b) anatomic and functional alterations of the lung due to congenital heart diseases are mediated through the increased pulmonary blood flow with or without transmission of the systemic blood pressure to the pulmonary vasculature, and c) anatomic and functional alterations of the right ventricle due to primary or secondary lung diseases are mediated through arterial pulmonary hypertension. In summary, the interrelationships between heart and lung diseases are mainly mediated through the pulmonary venous or pulmonary arterial hypertension.