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Biomedical subjects

A Raviele

Publications and source records attributed to A Raviele.

97 records · Page 6Linked to original sources
PubMed1977

[The mechanism of the chronic supraventricular tachycardia: an intracavitary electrophysiological study (author's transl)].

Chronic Supraventricular Tachycardia (CST) or Chronic Atrial Tachycardia is a relatively rare arrhythmia. Because of very poor number of cases studied with electrophysiologic techniques its mechanism is still debated. Three cases of CST, one of persistent type and two of repetitive type, are reported. His bundle electrogram, high and low right atrial electrograms and atrial stimulation were performed in every case, ventricular stimulation in only one case. The Amiodarone, Pindolol, Verapamil and vagal manoeuvres effects were evaluated in all cases. The site of origin of tachycardia, atrial in cases 1 and 3 and junctional in case 2, was estabished by atrial map. The electrophysiologic findings suggested the presence of an ectopic focus in cases 1 and 3 and of an AV nodal re-entry circuit in case 2. Our results and those of the literature indicate that the site and the mechanism of CST, as in paroxysmal supraventricular tachycardia, is not univocal. Their electrophysiologic evaluation by means of endocavitary techniques can allow a more satisfactory therapeutic approach.

Adolescent↗
PubMed1976

[The vectorcardiogram of the normal child, 2-12 years of age (author's transl)].

Morphological aspects and the most important vectorial parameters of the VCG (Frank method) of normal children, aged 2 to 12 years, were analyzed. The total group consisted of 110 subjects (10 for each )ear) subdivided into three subgroups of progressive age. Semeiologic evaluation of the QRS in the frontal and sagittal planes was not significant because of the stereotypes of the figures. In the horizontal plane the majority of cases showed typical triphasic development of the vectorial groups, while biphasic morphology was found in the minority. The triphasic loop presented 1) a balance between anterior and posterior forces which was more frequent in the youngest children, 2) a posterior orientation which was more frequent in the oldest children or 3) an anterior orientation which was infrequent. Since the anterior orientation of triphasic QRS was not related to the age -- it may also be seen in normal adults -- it was attributed to a variation of ventricular activation. The biphasic loop was attributed to immaturity of ventricular conduction. The evaluation of quantitative parameters was in agreement with the results of other studies. The changes of initial and intermediate vectors were probably due to the more important development of the left ventricle. The QRS duration increased with age. The T loop was posterior in the majority of the youngest children and progressively advanced with age, although it remained posterior in an important number of cases of children aged twelve.

Age Factors↗
PubMed1976

[Morphological aspects and electrophysiological evaluation of the vectorcardiogram in inferior myocardial infarction (author's transl)].

The purpose of the paper is to evaluate the vectorcardiographic characteristics of the QRS in inferior myocardial infarction, now extended and modified in the light of recent advances in electrophysiology. The VCGs (Frank system) of 70 patients with old inferior myocardial infarction were analyzed. The most important parameters previously considered by others and the behaviour of the different vectorial groups were considered. The results of the analysis of these parameters were concordant with those obtained by others. The morphologic evaluation of the QRS on different planes allowed our cases to be divided into five vectorcardiographic groups. The evaluation of the morphological aspects of the QRS for a more sure diagnosis of myocardial infarction, specially considering false positive cases, was considered from the semeiological point of view. Moreover, it was shown that some alterations of VCG cannot be apparent electrocardiographically. The electrogenetic meaning of vectorcardiographic alterations, probably related with depth and width of necrosis and with conduction disturbances in the subdivisions of left bundle branch, were evaluated.

Adult↗
PubMed1975

[Evolutive study of the VCG in the first week of the normal newborn infant (author's transl)].

The vectorial and morphological variations of the VCG (Frank method) during the first seven days of life of sixteen normal newborn infants were analyzed. A byphasic distribution of the QRS vectors in the horizontal plane was found at birth. Successive observations showed a rising of initial forces of left septal activation and a slight increase of left parietal forces. The T loop variations were more remarkable, being probably correlated with rapid postnatal hemodynamic modifications. After a few days the T loop was oriented posteriorly and to the left, not changing this direction for many year. The P loop did not differ from the adult's in the majority of cases. Sometimes it showed a figure-or-eight rotation in the horizontal plane, probably due, according to the authors, to a different pathway of atrial activation.

Age Factors↗
PubMedDate not supplied

Transesophageal echocardiographic evaluation of the morphologic and hemodynamic cardiac changes during ventricular fibrillation.

To analyze cardiac motion during ventricular fibrillation (VF), we used transesophageal echocardiography to study nine male subjects, aged 44 +/- 7 years, affected by heart disease who have poor left ventricular function, during implantation of an Implantable Cardioverter Defibrillator, when VF is induced several times to determine the defibrillation threshold. Wall and valvular motion, transmitral and transaortic blood flow, and blood echoreflectivity were evaluated in all patients. Moreover, in basal conditions, during VF, 1 and 5 minutes after restoration of basal rhythm, we calculated the left ventricular end-diastolic volume (EDLVV) and area (EDLVA), the left ventricular end-systolic volume and area, the ejection fraction, and the fractional area change with a four-chamber echocardiographic view. At the onset of VF, the myocardium and valves exhibited a chaotic motion. About 10 seconds later the oscillatory movement of the heart walls became more ample and regular; the mitral valve showed a cyclic closure and opening with a forward flow, and the aortic valve exhibited similar behavior, although at a lower intensity. A spontaneous echo contrast appeared inside the atrial and ventricular cavities, gradually becoming an incrt homogeneous mass that was completely flushed away with the restoration of the basal rhythm. When VF started, EDLVV (286 +/- 98 ml) and EDLVA (50 +/- 16.5 cm2) decreased abruptly (EDLVV = 182 +/- 65 ml, p < 0.02; EDLVA = 38 +/- 9.2 cm2,p < 0.05); so did ejection fraction (31.8% +/- 15% versus 11% +/- 5%; p < 0.003) and fractional area change (25.8% +/- 6.5% versus 7% +/- 3.4%; p < 0.001). When the basal rhythm was restored, the heart extended again and EDLVV, EDLVA, ejection fraction, and fractional area change after 1 and 5 minutes were similar to those calculated before induction of VF. This behavior was observed during both the first and last induced VF. Thus during VF, great variations of heart morphology and dynamics, as well as blood echoreflectivity, occur; the heart seems to make attempts to organize its dynamics during the arrhythmia. Repeated episodes of VF and defibrillation with low energies do not seem to worsen left ventricular dynamics even in impaired hearts.

Adult↗