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Biomedical subjects

R Fenici

Publications and source records attributed to R Fenici.

At least 37 records · Page 2Linked to original sources
PubMed1980

[Surface recording technique of His bundle potential in man].

A method is presented for the non-invasive recording of His bundle electrical activity from the body surface in man. Several bipolar ECG leads were employed: precordial, Frank "x" and Frank "z". Signals were filtered (30-300 Hz), highly amplified (5 x 104) and averaged. Digital averaging was performed on line by a microcomputer (OTE Biomedica Neuroaverager mod. 1172). Surface investigation was performed in 10 patients affected by different conduction pathology simultaneously with HBE recordings for diagnostic purpose and in 5 normal volunteers only incruently. Highly repeatable electrical deflections (B waves) were recorded in the PR segment. In all patients a good correspondence between surface (B wave) and intracardiac (H wave) was found. Atrial pacing and pharmacological test were used in order to ascertain the real source of B wave.

Bundle of His↗
PubMed1980

[Automatic analysis of systolic time intervals using polygraphic examinations].

For clinical purpose, poligraphyc signals are analyzed: systolic time intervals (STI) and all other significative magnitudes are measured. A system of modular programs (ATS), in Assembler and Fortran IV languages, digitalizes, filters and analyzes three simultaneous analogical signals: ECG, PCK and CP. ATS, adapted polynomial and gonyometrics leats-squares smoothings to the signals for leaving-out spikes and drifts, employs algorhythms that, by a statistic knowledge of the thresholds of the fist derivative of each signal and of the globality of smoothed signals, converge to the measures of the required significative magnitudes. A statistic investigation (on 100 samples) showed that ATS is better than every manual analysis in terms of efficiency, speed and amount of information. In conclusion ATS program is suitable for clinical purposes.

Adult↗
PubMed1980

T wave abnormalities in top-ranking athletes: effects of isoproterenol, atropine, and physical exercise.

Eight cases of top-ranking athletes with "repolarization disorders" are reported. All subjects were asymptomatic and were otherwise suited for excellent cardiovascular performances. Seven athletes did not show any evidence of heart disease. Seven had MVP (mitral valve prolapse). Umprompted variability of ECG tracings was observed in three cases. Both isoproterenol infusions (IS) and maximal physical effort (EX) normalized T wave (abnormalities in 100% of cases, while atropine (AT) was ineffective despite an increase in heart rate greater than that caused by IS. The authors emphasize the usefulness of combined use of the EX and IS tests in ascertaining the clinical significance of T wave changes in healthy athletes. A "neurogenic" mechanism is proposed by the authors for the pathogenesis of these T wave abnormalities. This hypothesis may explain the umprompted variability of ECG tracings and T wave normalization after maximal physical effort and isoproterenol infusion.

Adolescent↗
PubMed1980

Wenckebach second-degree A-V block in top-ranking athletes: an old problem revisited.

The occurrence of Wenckebach second-degree (Mobitz I) A-V block in apparently normal persons still provides a puzzle for the cardiologist, as the benign nature of this event has been recently questioned. This problem becomes more intriguing when Wenckebach A-V block is encountered in asymptomatic top-ranking athletes, because of medico-legal implications. We report 10 cases of highly-trained athletes, including three with mitral valve prolapse (MVP) features, with a spontaneous or induced Wenckebach second-degree A-V block. Previous ECGs of six subjects, dating from a maximum of 6 years to a minimum of 18 months, were available. Deterioration of A-V conduction has never been documented and all six cases have remained asymptomatic for the whole follow-up period. Athletes have been submitted to a protocol study consisting of ECG recording at rest, during, and after vagal and sympathetic reflex maneuvers, drug administration (isoproterenol and atropine), submaximal and maximal exercise. Nine subjects have been considered to have "normal" responses of the A-V node to provocative tests, since conduction disturbances were improved or normalized by reflex sympathetic stimulations and were completely normalized by autonomic drug administration and exercise. One athlete showed "abnormal" responses to tests. In order to give a conclusive prognostic and medico-legal assessment, we advised him to submit to an invasive electrophysiological investigation. Wenckebach second-degree A-V block in athletes may be a more common finding than so far described, especially when a systematic search is made. In our opinion, this event can still be considered a vagally-induced benign feature of athlete's heart, provided that an immediate improvement of A-V conduction is obtained in response to reflex sympathetic maneuvers, and that a complete normalization after sympathomimetic and vagolytic drug administration and physical exercise is observed. The clinical histories of our athletes and the observed complete disappearance of conduction disturbances after detraining, strongly support this opinion. Wenckebach second-degree A-V block in asymptomatic athletes with MVP features probably does not affect the prognosis if similar favorable responses to the aforesaid tests are observed.

Adolescent↗
PubMed1978

[Recording of the right atrial monophasic action potential in humans. I. Subjects not affected by arrhythmia].

Using a bipolar suction electrode technique, right atrial monophasic action potential (RA MAP) was recorded in 18 patients surely free from any kind of arrhythmia. Two morphologically different kinds of RA AMP were obtained: the former exhibiting an evident transition between phase 1-2 (plateau) and phase 3 of repolarization (FP), the latter without any appreciable palteau (FL). Electrophysiological properties of human myocardial atrial tissue have been investigated by microelectrode technique. The two types of MAP recorded by us resemble the former the action potential obtained from conducting specialized fiber, the latter the action potential of contractile fibers. A statistically significant difference in RA MAP duration measured at 90% level of repolarization (D 90%) was found between the two kinds of MAP: therefore we suggest to perform quantitative evaluations and pharmaco-ogical investigations only including MAPs of similar morphology. The intraindividual variation coefficient of D 90% may be considered an expression of the range of variability of repolarization duration in man; we suggest that only MAPs of similar configuration should be accepted for its calculation in order to avoid errors of evaluation.

Action Potentials↗
PubMed1977

[Mobitz type II 2d degree atrioventricular block. Clinical and electrophysiological study].

His Bundle Electrogram (HBE) was recorded in 20 patients with Mobitz type II block. All patients were clinically evaluated and a history of syncope was carefully investigated. These patients were prospectively followed (mean follow up: 20,4 months). ECG showed LBBB in 9 patients, RBBB + LAHI in 6, RBBB + LPH in 3, LAH in 1, left axis deviation in 1. In all patients HBE revealed prolungation of H-Q interval and localization of block within the His-Purkinje system (within H in 4) distal to H in 16. In 9 patients intermittent complete heart block localized within the H-P system was documented during HBE recording. 15 patients (75%) experienced syncopal attacks. All patients underwent implantation of permanent demand pace-maker, without further episodes of syncope. Since the site of block is the most important determinant of prognosis, in all patients with Mobitz type II block, whether or not symptoms are present, prophylactic implantation of pace-maker is indicated, because high incidence of progression to complete heart block, with potential risk of Adams-Stokes syndrome and sudden death.

Adult↗