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Biomedical subjects

A de Micheli

Publications and source records attributed to A de Micheli.

At least 19 recordsLinked to original sources
PubMed1987

Interatrial conduction and STa in experimental atrial damage.

Right (RA) and left atrial (LA) damage was produced with a subepicardial infiltration of 96 degrees alcohol in two groups of dogs. In six other dogs the left or right portion of the interatrial band was also injured. Conventional ECG and supplementary unipolar leads were recorded using photographic and direct inscription polygraphs at paper speeds of 50 and 100 mm/sec. Control, immediate postinjury and late tracings were obtained. A-V block was provoked to determine QTac. Slowing of heart rate and slight widening of the P wave and P-R interval were observed with both types of atrial damage. In four cases low right atrial rhythm was detected: two showed anatomo-histological sinus node involvement in right atrial injury. Qp waves were registered over the left precordium with necrosis of both sides, but were more frequent with RA damage. Damage of the left portion of the interatrial band delayed left atrial activation and split P waves in the precordial leads. Damage of the RA distorts the initial vectors, magnifying the left ones and simulating LA enlargement. The Qp registered on the RA is also detected by surface leads. Contrary distorted LA depolarization increases the RA vector and delays the left, ones, giving rise to greater asynchronsim and bimodal P waves.

Animals↗
PubMedDate not supplied

[Protective effect of glucose-insulin-potassium solutions in myocardial damage caused by emetine].

This study was carried out on 170 dogs. Cardiotoxic effects of doses of 15 mg/kg of emetine hydrochloride were studied in 20 dogs. 20 mg/kg of emetine hydrochloride were administered intravenously over 60 min. to the remaining 150 animals. These dogs were distributed in groups of 25. One group received emetine alone. Phleboclyses with saline serum, glucose-insulin-potassium, glocose-insulin, glucose-potassium and glucose serum alone, respectively, were administered to the other 5 groups during the emetine infusion and cardial contraction and several electrograms were recorded. Mean systolic blood pressure was measured continuously in the femoral artery. Observations covered a 4 hour period. During the infusion of emetine alone, ventricular myocardial contraction and systemic arterial pressure decreased abruptly. Intra-atrial, atrio-ventricular and intraventricular conduction disorders, as weel as primary ventricular repolarization changes, were also observed. At the end of this infusion, the Q-T interval increased 25% and the heart rate decreased 26% of the control values. In the group also receiving glucose-insulin-potassium solution, the fall of the ventricular contraction amplitude was significantly less than in animals given emetine alone. Primary ventricular repolarization changes were less evident. The mortality rate reached only 4 per cent. In conclusion, the doses of emetine hydrochloride employed here have depressive cardiocirculatory effects. Glucose-insulin-potassium solution, administered simultaneously with emetine, seems to have a favorable metabolic effect against the emetine cardiotoxicity. This protective action of the G-I-K solution is superior to that obtained with each component, administered separately, and with saline serum.

Animals↗
PubMedDate not supplied

[Anatomo-vectorcardiographic correlation in ventricular growth in congenital heart diseases].

Anatomo-vectorcardiographic correlations were studied in 59 cases of congenital heart disease. In the group with interventricular septal defect and pulmonary hypertensión, a statistically significant correlation between the thickness of the free right ventricular wall, at its outflow tract, and the inscription time of the vertex of the S loop, was found. In the group of Fallot's tetralogy, the segmentary hypertrophy of the right ventricle, which is the most frequent, explains very well the terminal portion of frontal and sagittal vectorcardiograms located below the 0 point. In the group with interatrial septal defect and pulmonary hypertension, a statistically significant correlation between the thickness of the antero-lateral superior third of the free right ventricular wall and the inscription time of the vertex of the S loop, was shown. In the group of congenital malformations with repercussion on the left ventricle (interventricular septal defect, patent ductus arteriosus and coarctation of aorta), a statistically significant correlation between the anatomical findings of a hypertrophied superior third of this ventricle and the inscription time of the vertex of the R loop, was observed.

Adult↗
PubMedDate not supplied

[Familial occurrence of Wolff-Parkinson-White syndrome. Report of a family group and review of the literature].

A family group of nine members was studied, two of which had W-P-W syndrome; the father type A; and the son type B. These two patients were studied from the clinical electrocardiographic and vectocardiographic point of view; and they were subject to hisian electrogram recordings. The atrial-ventricular conduction under basal conditions and during atrial stimulation is analyzed. In the first case, potential H is registered after the beginning of delta wave of the ventricular complexes in lead II. In th second case, atrial-ventricular conduction can only occur through the abnormal via (no H potential and register of delta wave in the periferial simultaneous lead), or only through the normal via (evidence of potential H with a normal H-V interval and no delta wave in the periferial line of control). The bibliography of the observation that in most family groups described up until now, there is a good correlation concerning sex. This gives the impression to be a genetic disorder linked to sex.

Adult↗
PubMedDate not supplied

[Electro-ventorcardiographic manifestations of ventricular inversion with transposition of great arteries].

Electrocardiograms obtained in two groups of patients with inversion of the ventricles and transposition of the great arteries, were analyzed: group I corresponding in situs solitus and group II to situs inversus. This series comprises 36 cases (29 of group I and 7 of Group II), in which the diagnosis of the main congenital heart disease --ventricular inversion-- and of the associated defects was established by angiocardiography. In 7 cases of group I and in one of group II, the angiocardiographic diagnosis was proved at least in part during open heart surgery. Direct anatomic study was possible in 5 more cases of group I and in 2 more of group II. Each group comprises two subgroups: A, without RBBB, and B, with RBBB of different degrees. Group I consists of 11 cases of subgroup A and 18 of subgroup B. In group II there were 2 cases of subgroup A and 5 of subgroup B. Vectorcardiograms were obtained following Grishman's method in 17 cases of group I (8 of subgroup A and 9 of subgroup B) and in 3 cases of group II (1 of subgroup A and 2 of subgroup B). In 7 cases of group I (5 of subgroup A and 2 of subgroup B), it was possible to record also the vectorcardiographic curves following Frank's method. Electro and vectorcardiographic findings were correlated with hemodynamic data and, in some cases, also with anatomic ones.

Adolescent↗
PubMedDate not supplied

[Response of experimental ventricular tachycardia to class I anti-arrhythmia agents].

Active ventricular arrhythmias were provoked in damaged dog myocardium to study their response to some antiarrhythmic agents of Vaughan-Williams' class I. Dogs anesthetized with intravenous sodium pentobarbital (30 mg/Kg) were intubated and submitted to artificial ventilation using a Palmer pump. An infarction was produced near the apex of the left ventricle by intramural injection of 1-1.5 ml of phenol, and 30 to 60 min later, minute crystals of aconitine were introduced into the periphery of the infarcted area. Once ventricular tachycardia appeared and became stable, corresponding records were obtained and the antiarrhythmic agent to be studied was administered through the superior vena cava over a period of 5 to 15 min. Electrocardiographic tracings were registered at constant intervals in order to detect the recovery and duration of sinus rhythm. The reappearance of arrhythmia was always required in order to consider the action of the medication administered positive. High doses of lidocaine (6 mg/Kg) reestablished transient sinus rhythm in 23% of 35 treated dogs. Fifteen mg/Kg of mexiletine reestablished it in 45% of 22 animals and 2.5 mg/Kg of propafenone restored it in 39% of 18 animals receiving this drug. The positive effect of these antiarrhythmic agents of groups I B and I C consisted essentially in controlling no-rapid tachycardias with the "wave jumping" phenomenon and fusion beats, which may be due to activity of ectopic foci. Very rapid ventricular tachycardia with "wave jumping" generally did not respond to the antiarrhythmic agents tested. These tachycardias may be maintained by reentry or by the intervention of calcium-dependent potentials. Rapid ventricular tachycardias without extensive "wave jumping" also occurred. These were never controlled by the group I B antiarrhythmic agents, although they were sometimes suppressed with propafenone. These tachycardias probably originated near the intraseptal barrier. In few animals, amiodarone of class III was employed with a marked hypotensive effect.

Amiodarone↗
PubMedDate not supplied

[Vectorcardiographic manifestations of right ventricular enlargement].

The basic criteria for the vectorcardiographic diagnosis of right ventricular enlargement are discussed, in context with the course of myocardial activation. Right ventricular dilatation, secondary to isolated diastolic overloading (atrial septal defect) shows basically different degrees of dextrorotation. The ventricular curve starts to the left on the frontal and horizontal planes, and forward on the last one. Cases with right ventricular hypertrophy, produced by sustained systolic overload, are also evaluated. When the hypertrophy is generalized (pulmonary valvular stenosis), there is an increase in the manifestation of all the resulting vectors of activation of this ventricle: IIs, IIr, and IIIr. As a resultant of these changes, the ventricular curve presents a clockwise rotation in the three planes, and is oriented to the right and forward, with its terminal portions generally located above the E point. When the right ventricular hypertrophy is of the segmentary type, there is an increase of the manifestation of only some of the resulting vectors of the activation of this ventricle. For example, the vector IIr will be increased in cases of tetralogy of Fallot, while the IIIr will be increased in some cases of obstructive chronic pulmonary hypertensive cardiopathy. The T loop, of secondary type, generally opposes the vector IIr on the horizontal plane, and the IIIr on the frontal plane. When an important right ventricular dilatation is associated to a right bundle branch block of intermediate degree, owing to their proximity, the manifestation of the electromotive parietal forces is increased at the expense of the septal ones. This phenomenon produces a characteristic appearance of the SH loop, narrow and with a clockwise rotation.

Adolescent↗
PubMedDate not supplied

[Vectorcardiographic manifestations of left ventricular and biventricular enlargement].

The basic criteria for the vectorcardiographic diagnosis of left ventricular and biventricular enlargements are discussed on the basis of the myocardial activation sequence. Left ventricular dilatation, secondary to isolated diastolic overloading, increases the manifestation of all the vectors resulting of the activation of this ventricle. These changes reflect the proximity of the left ventricular walls to the exploring electrodes. The vectors above mentioned project themselves as wide ventricular curves with counterclockwise rotation on the three planes. The T loop, of secondary type, is concordant in its orientation with the R loop. Cases with left ventricular hypertrophy, produced by a sustained systolic overloading, are also described. In the presence of global left ventricular hypertrophy without LBBB, the manifestation of all the vectors resulting from the depolarization of this ventricle (I, IIl, IIIl), is increased. This is due to a prolonged duration of the corresponding activation fronts. These vectors are projected on the different segments of the ventricular curves and they show a counterclockwise rotation on the three planes. When LBBB is also present, the first septal vector is not evident. The T loop, of secondary type, opposes the R loop on the frontal and horizontal planes. The presence of left ventricular hypertrophy of the segmentary type, generally increases the manifestation of the vector I, and sometimes, also that of the vector IIIl. When both ventricles are hypertrophied, the electromotive forces of the chamber more severely affected predominate in the vectorcardiographic records.

Cardiomegaly↗
PubMedDate not supplied

[The clinical and electrophysiological characteristics of patients with idiopathic ventricular tachycardia].

Clinical and electrophysiological characteristics in 20 patients with clinical ventricular tachycardia and normal hearts documented by physical examination, echocardiography, and angiocardiography were analysed. There were 11 males and 9 females. All patients had sustained ventricular tachycardia without hemodynamic instability during tachycardia. A right bundle branch block morphology of ventricular tachycardia was present in 14 patients and left bundle branch block morphology in six patients. During electrophysiologic studies, ventricular tachycardia was induced in 10/15 (66%) patients. Intravenous verapamil terminated the ventricular tachycardia in 9/10 (90%) of cases. However oral verapamil not prevented recurrences. Among 14 patients on whom exercise tests were performed, only two had exercise-induced ventricular/tachycardia. Late potentials were positive in 3/14 (21%) cases and one patient died suddenly during exercise without antiarrhythmic drugs.

Adolescent↗
PubMedDate not supplied

[Atrioventricular and ventriculoatrial conduction in patients operated on for the Wolff-Parkinson-White syndrome].

Over the last decade the surgical treatment of the Wolff-Parkinson-White syndrome has been well accepted. It is important to make an early diagnosis for surgical success. For this purpose we utilized programmed electrical stimulation to assess the functional characteristics of atrioventricular and ventriculoatrial conduction in our post-operative patients. In 55% of the cases we found accelerated nodal conduction. Programmed electrical stimulation correctly identified 90% of successfully treated patients. We did not found any false positive curve, therefore, this method has a high specificity. We concluded that in post-operative patients with the Wolff-Parkinson-White syndrome: 1- There is a high incidence of accelerated nodal conduction and 2- programmed electrical stimulation can correctly identify most of the patients who were successfully treated.

Adolescent↗
PubMedDate not supplied

[About "sudden death"].

Explore the source record for details and available documents.

Death, Sudden, Cardiac↗
PubMedDate not supplied

[Electrophysiologic effect of intravenous propafenone in supraventricular tachycardia].

The electrophysiologic effects of intravenous propafenone were studied in twenty six patients with supraventricular tachycardias. Ten patients (38%) with intranodal reentrance tachycardia common type, and sixteen patients (62%) atrioventricular orthodromic reentrance tachycardia. Propafenone (2 mg/kg intravenously) given over ten minutes period caused termination of the intranodal reentrance tachycardia in 60% of the cases and 50% to the patients with atrioventricular reentrance tachycardia. The antiarrhythmic effects observed are related to the slowing of the conduction velocity and to the prolongation of the refractoriness in the AV node and accessory pathways preventing the reentrance mechanism. The reinduction of the tachycardia was possible in 46% of the patients. This effects was more significative in the group with accessory pathways (50%), and 40% of the patients with intranodal reentrance. The supraventricular tachycardia was inducible by programmed electrical stimulation in 46% of the patients. None of the patients developed side effects to the administration of the propafenone.

Adolescent↗
PubMedDate not supplied

[Surgical treatment of supraventricular tachycardias (Wolff Parkinson White and Occult Kent). Experience at the "Ignacio Chávez" National Institute of cardiology].

We report our initial experience in the surgical section of the accessory pathway in thirteen patients: eight patients with Wolff Parkinson White syndrome and five with accessory pathway functioning only in direction ventricle to atrium (Kent concealed), with recurrent episodes of paroxysmal supraventricular tachycardia with no response to medical treatment. Three of these patients had episodes of auricular fibrillation with interval RR lower than 250 msec and one patient presented syncope. A total of fifteen accessory pathways were sectioned: 7 left lateral, 5 left posterior, one left posterolateral, one right lateral, and another one right anteroseptal. In the same procedure two patients had correction of another heart malformation: one with patent ductus arteriosus and another with and another with atrial septal defect. All patients had successful outcome, one of them needed a second surgery for persistent accessory pathway. We had two post-operatory complications: one mediastinitis and one patient with ectopic auricular tachycardia.

Adolescent↗
PubMedDate not supplied

[Ebstein's anomaly with the Wolff-Parkinson-White syndrome].

Thirty-three patients were studied with Ebstein's anomaly, associated to Wolff-Parkinson-White syndrome with the purpose of analyze their electrophysiologic characteristics. In this patients the right preexcitation was before the activation of the right ventricle mass, overshadowing the manifestations of the right bundle branch block (usual in patients with Ebstein's anomaly without preexcitation). In conclusion the absence of manifestations of right bundle branch block in the presence of Ebstein's anomaly diagnosed by hemodynamic study or echocardiography let us think in the coexistence of the preexcitation and suggest the pertinent electrophysiologic study; as the association of supraventricular tachycardia in this group is very high (94%) most of them paroxysmal orthodromic tachycardia.

Adolescent↗