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Biomedical subjects

G A Medrano

Publications and source records attributed to G A Medrano.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

[Intraventricular conduction disorders in experimental right septo-parietal infarction].

In 16 mongrel dog hearts the electrocardiographic (ECG) and vectocardiographic (VCG) alterations provoked by chemical necrosis within the anterior free right ventricular wall and anterior portion of the interventricular septum were studied. The necrosis was associated to isolated right bundle branch block (RBBB), or the latter associated to left anterior subdivisional block (LASB). The abnormal Q waves from the epicardial right ventricular wall were transmitted to the right thoracic leads in 25% of the cases with isolated RBBB instead of 43% in its absence. However the addition of a LASB or LASB+ left posterior subdivisional block (LPSB) increased its presence to 83.3%. Nevertheless, rSRS' with slurred first S wave were observed on the right thoracic surface as well as on the right epicardium and ventricular chamber. Those morphologies have a very significant value for right ventricular necrosis in the presence of RBBB, increasing the percentage of positive diagnoses. Anteroseptal necrosis was recognized more frequently (93.7%) in the epicardial unipolars than in thoracic leads (75%), but positive diagnosis increases to 93.3 in the latter when one or two left subdivisional blocks were provoked. Vectocardiographic loops showed an earlier backward displacement of centrifugal limbs in the horizontal and sagittal planes not very different of that observed in septal necrosis for humans. These signs were more frequently seen with RBBB than without it, and even more oftenly, when a left distal block was associated. Nevertheless, ECG right thoracic leads alterations are more convincing and must be done and analysed in order to confirm the diagnosis.

Animals↗
PubMedDate not supplied

[Electrocardiographic diagnosis in atrioventricular discordance].

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.

Adolescent↗
PubMedDate not supplied

[Right blocks in interauricular communication].

The purpose of this study is to establish some electro-vectorcardiographic criteria useful in the differential diagnosis of right fascicular and truncular blocks in 72 cases of atrial septal defect proven by hemodynamic and surgical data. In all cases, the conduction disorder was analyzed by conventional electrocardiograms; in many cases, additional right unipolar thoracic and intracavitary leads were utilized; and in 22 cases high fidelity records were obtained with a Simultrace Recorder V6R. Right block was studied in vectorcardiographic curves recorded in three planes following the method of Grishman's cube. This block was considered as proximal or truncular in 46 cases: of minor degree in 8 and of intermediate degree in 38. In these cases the difference in time of onset of the intrinsicoid deflection between the free right ventricular wall and the low anterior right septal mass was up to 30 msec. Distal or fascicular block was diagnosed in 26 cases: RASB in 10 and RPSB in 16. The difference in time of onset of the intrinsicoid deflection between the free right ventricular wall and the right anterior-inferior septal mass exceeded 30 msec. The highest values were observed in aVR and V1, in the cases with RASB; in aVF, V3R and V1, in the cases with RPSB. The SF loop was diphasic in the presence of proximal block, appearing above the 0 point in the cases with RASB and below this point in the cases with RPSB. SH loop was anterior when truncular block existed, lateral when there was RASB and plus or less diphasic in the cases with RPSB. Sometimes, Q-Tc interval was prolonged in V2 and V3, grossly related to telediastolic pressure in the right ventricle. The facts reported here permit the formulation of the following conclusions: 1. The morphologic aspects of the electrocardiographic and vectorcardiographic curves are very useful for recognizing RASB. In order to establish the differential diagnosis between RBBB of intermediate degree and RPSB, it is necessary to perform a thoracic electric mapping. 2. The clockwise rotation of the entire SH loop, observed in 27 of 38 cases of intermediate degree RBBB, is probably due to the more important manifestation of right parietal electromotive forces because of the ventricular enlargement. 3. The prolonged Q-Tc interval in some right unipolar leads reflects the diastolic overloading of the homolateral ventricle (increased telediastolic pressure).

Adolescent↗
PubMedDate not supplied

[Exercise tests in pneumopathy patients].

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.

Adolescent↗
PubMedDate not supplied

[The action of intravenous flecainide in experimental ventricular arrhythmias].

Experimental ventricular tachycardias were provoked in dog hearts with minute crystals of aconitine introduced into the periphery of an infarcted area, produced by intramural injection of 1-1.5 ml of phenol near the apex of left ventricle. The response of these tachycardias (VT) to flecainide was studied. Leads II, aVL, intraventricular right and left unipolar records, as well as one on the superior vena cava (SVC) were registered under control conditions, with VT and after the injection of this antiarrhythmic agent. This injection was infused into SVC over 15-20 minutes. Records were obtained with constant intervals, waiting for the recovery of sinus rhythm (SR) and the posterior reappearance of ventricular tachycardia. The experiments were performed 6 to 8 hs with continuous infusion of Hartmann' solutions. Throughout these periods, the variations of systemic systolic pressure were registered. Of the 22 dogs receiving 4 mg/kg of flecainide, transient SR was observed in 12 (55%), while in 4 (18%) this medication had no effect. Heart block presented in 2 animals and a fall of arterial pressure in 4. Of another 25 dogs receiving 2.5 mg/kg of flecainide, similar to clinical doses, transient SR appeared in 11 (44%), while in 3 (12%) SR was not observed. In other 2 groups, each of 15 dogs, the repeated antiarrhythmic action of flecainide was present in 33% with 4 mg/kg and in 20% with 2.5 mg/kg. This medication had no effect in 20% of the former and in 40% of the latter. However the low dose did not produce undesirable effects. Furthermore these differences were no significant statistically. Flecainide is effective in certain experimental ventricular tachycardias probably related to sodium-dependent potentials.

Aconitine↗
PubMedDate not supplied

[Effect of intravenous verapamil in experimental ventricular arrhythmia].

Experimental ventricular tachycardias (VT) were provoked in dog hearts with minute crystals of aconitine introduced into the periphery of an infarcted area, produced by intramural injection of 1-1.5 ml of phenol. The response of these tachycardias to verapamil was studied. Leads II, aVL, intraventricular right and left unipolar records, as well as one on the superior vena cava were registered under control conditions, with VT and after the injection of the antiarrhythmic agent. This injection was infused into superior vena cava over 15-20 minutes. Records were obtained with constant intervals, waiting for the recovery of sinus rhythm (SR) and the posterior reappearance of ventricular tachycardia. The experiments were performed 6 to 8 hs with continuous infusion of Hartmann's solutions. Throughout these periods, the variations of systemic systolic pressure were registered. Of the 75 dogs treated with 0.2 mg/kg of verapamil, SR was recovered transiently in 30 (40%), while it exerted no antiarrhytmic effect in 19 (25%). Arterial systolic pressure fell importantly in 10 animals (13%). In 3 other groups, of 15 dogs each, comparative administration of verapamil vs lidocaine (I), vs mexiletine (II) and vs propafenone (III), was tried. In Group I, verapamil reestablished transient SR in 73% and lidocaine in only 7%; in II, SR resulted from verapamil in 33% and from mexiletine in 7%; in III, SR reappeared in 21% with verapamil and in 28% with propafenone. The repeated positive effect of verapamil was found in 33% of 15 experiments. This drug is effective in certain experimental ventricular tachycardias, probably related to calcium-dependent potentials.

Animals↗
PubMedDate not supplied

[Study of the heart conduction system in atrioventricular disorders].

A His electrogram was registered with a Castillo tripolar catheter in seven patients with atrio-ventricular discordance and transposition of the great arteries (corrected transposition). They all had ventricular septal defect, six had pulmonary stenosis. two had atrial septal defect, and only one patient presented first degree AV block. The QRS was of normal duration, 4 had RBBB morphology in the left precordials. Two with ASD and VSD had a prolonged P/A interval. In one, the His recording was polyphasic with a prolonged H-V (55 msec) and two others showed a wide polyphasic His potential (25 and 26msec), with a prolonged H-V. These 3 cases with prolonged His had a minor degree of RBBB. The remaining 3 showed normal AV conduction. In all, the Purkinje electrogram was registered. The duration of the Pu potential and the Pu-V were normal. Corrected transposition shows a high incidence of slow AV conduction, frequently not detectable in the usual electrocardiogram in agreement with previous anatomo-pathological studies. The distal block would explain the frequency of complete AV block with low cardiac output and frequent sudden death in this type of heart disease. The distal block would compel us to take e more agressive steps in its treatment. Atrial septal defect with slowing of the intra-arial conduction is not detected in the electrocardiogram.

Electrocardiography↗
PubMedDate not supplied

Left anterior fascicular block concealing anteroseptal infarction.

Fascicular blocks may modify electro-cardiographic morphologies and signs of necrosis may be masked. This report concerns the case of a patient with an anteroseptal myocardial infarction who developed a transient left anterior fascicular block. An explanation for the concealment of the signs of necrosis is proposed, based on an analysis of the modified activation process by means of a vectorial representation.

Electrocardiography↗
PubMedDate not supplied

[Intermediate syndrome: electrocardiographic, angiographic and clinical characteristics and their development under medical treatment].

An emphasis is placed on the definition and separation of the acute coronary insufficiency from the other "status anginosus", because the natural history and its physiopathology is of a distinct nature and actually still not very precise. A group of 19 patients was studied which filled all the clinical, electrocardiographic and enzymatic requisites of the genuine acute coronary insufficiency. Among these a subgroup of 13 patients was found with the classic Prinzmetal syndrome. In all cases the following were studied: antecedents, risk and coronary profile, the pain syndrome, electrocardiographic alterations, enzymatic modifications, coronariographic findings modifications, coronariographic findings and the ventricular function through ventriculography. The frequent occurance in the female sex is pointed out as well as the importance of the social and sensorial stress. We effected and described the correlation between the number and intensity of the pain crises and coronariographic findings. The electrocardiographic and coronariographic findings were correlated in the Prizmetal variety as well as in the entire group. An analysis was made of the correlation between the number and degree of coronary obstructions and the areas of ventricular diskinesia. The apparent paradox between an important number of cases with ventricular diskinesia and the limited number of cases with clinical and radiological left ventricular failure was mentioned and discussed. An analysis is made of the theoretic models of the ischemic heart disease in relation to the coronary macro and microcirculation and the possible influence of the catecolamines and the collateral circulation. The different physiopathological mechanisms introduced in this entity whose genuine world wide ocurrence is not very elevated. The evolution and morbi-mortality of those cases placed under medical care is analyzed.

Aged↗
PubMedDate not supplied

[Pre-excitation syndrome in monozygotic twins].

A family group of seven members is presented, two of which have pre-excitation syndrome. These subjects are identical twin brothers. One of them has the W-P-W syndrome tipe B, and the other has L-G-L syndrome. The latter had an associated atrial-septal defect, and the other twin had no associated cardiovascular lesions. Both underwent electrocardiographic and vectorcardiographic studies, as well as His bundle electrograms. In the case with W-P-W, the diagnosis was made by electrocardiography, and was confirmed by vertocardiography. The His bundle electrogram showed the habitual findings in this type of pre-excitation. The His bundle potential was preceded by the beginning of the delta wave. The patient with W-P-W had episodes of supraventricular paroxysmal tachycardia, some of these with antegrade conduction through the normal pathway, and others with conduction through the anomalous pathway. The other had a L-G-L syndrome, demonstrated by electrocardiography and vectorcardiography. During the register of the His bundle electrogram, he did not present pre-excitation, the tracings in basal conditions as well as during atrial stimulation were normal. The conclusion is that many factors exist which back up the hypothesis that the pre-excitation syndromes occur because of anomalous pathways, and that this type of alteration might have a sex linked genetic basis. This presumption appears to be confirmed by the presence of pre-excitation in identical twin brothers. Other possibilities are also discussed.

Child↗