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Biomedical subjects

M Di Biase

Publications and source records attributed to M Di Biase.

At least 37 records · Page 2Linked to original sources
PubMed1989

Programmed stimulation in patients with minor forms of right ventricular dysplasia.

Programmed electrical stimulation (PES) was performed in 17 patients, mean age 31 +/- 8 years, with minor forms of right ventricular dysplasia diagnosed because of (1) premature ventricular beats (PVBs) of left bundle branch block (LBBB) morphology; (2) no clinical or non-invasive evidence of cardiac abnormalities; (3) angiographic evidence of right ventricular wall motion abnormalities and bioptic findings of fibro-adipose infiltration. Fifteen patients had frequent and complex PVBs while two had sustained ventricular tachycardia (VT). During PES, sustained VT was induced in 2/2 patients with spontaneous sustained VT; ventricular repetitive responses were induced in 2/15 cases (13%) with complex and frequent PVBs. In conclusion, in minor forms of right ventricular dysplasia, PES induces VT only in patients with clinical VT; on the contrary, in patients with PVBs it is only possible to induce repetitive ventricular responses in a small proportion of cases; it is therefore not possible to select patients at high risk of developing severe ventricular arrhythmias.

Adult↗
PubMed1989

High doses of L-carnitine in acute myocardial infarction: metabolic and antiarrhythmic effects.

Fatty acids accumulate in the muscle cells in some carnitine deficiency syndromes due to a variety of genetic defects in intermediary metabolism. L-Carnitine administration may relieve this excess by transporting acyl compounds out of the cell as acylcarnitine. Similar fatty acid accumulation occurs during myocardial ischaemia because of the decreased rate of beta-oxidation, and this has been put forward as a cause of ventricular arrhythmias. This study was carried out to investigate whether administration of high doses of i.v. L-carnitine in patients with acute myocardial infarction could increase urinary excretion of acylcarnitine and reduce early ventricular arrhythmias. Fifty-six patients suffering from acute myocardial infarction, admitted to the Coronary Unit between 3 and 12 h after the onset of symptoms, were included in the study. The design of the study was double blind, parallel and placebo controlled. Allocation of treatment to patients was done randomly after stratification (time from onset of pain and site of infarction). The first group (28 patients) received intravenous L-carnitine at a dose of 100 mg kg-1 b.w. every 12 h for 36 h while the second group (28 patients) received placebo intravenously. Immediately before starting treatment two blood samples were taken (at 5-min intervals) and a further 16 samples were taken at regular intervals over the following 48 h. Patients' urine was collected over the same period of time. Concentrations of free carnitine, short chain acylcarnitine esters and long chain acylcarnitine esters in serum and urine were measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Incidence of 'dual A-V nodal pathways' in first- and second-degree type I supra-His A-V block.

The incidence of 'dual A-V nodal pathways', diagnosed on the basis of spontaneous or induced modifications in the PR interval, has been assessed in a group of 168 consecutive patients with first- (77) and second-degree (91) type I supra-His block. 'Dual A-V nodal pathways' were found in 12 cases (16%) with first-degree and in 7 cases (7.7%) with second-degree type I supra-His A-V block. His bundle recording confirmed the hypothesis that PR interval variations observed in these cases are due to modifications in the AH interval and thus to changes in A-V nodal conduction velocity. The electrophysiologic study also showed that the phenomenon was easily reproduced by atrial stimulation. The frequent association between 'dual A-V nodal pathways' and supra-His blocks suggests that the block mechanism should be studied in depth as it could have prognostic and therapeutic implications.

Adolescent↗
PubMed1987

Role of QT prolongation secondary to a postextrasystolic pause as a possible mechanism for the induction of ventricular fibrillation. Report of two cases.

Two patients developed ventricular fibrillation (VF) while undergoing continuous electrocardiographic monitoring. Analysis showed that VF appeared only when a particular combination of circumstances occurred: a postextrasystolic pause, QT prolongation of the subsequent beat and a premature ventricular beat that did not have a short coupling interval. The relevance of this sequence as a trigger mechanism of VF is discussed.

Aged↗
PubMed1987

Ventricular fibrillation induced by transesophageal atrial pacing in hypertrophic cardiomyopathy.

Sudden death is a rather frequent occurrence in patients with hypertrophic cardiomyopathy, yet the mechanism is uncertain in most cases. We describe a case of an 18 years old patient with a family history of hypertrophic cardiomyopathy and sudden death in whom ventricular fibrillation could be repeatedly induced by means of transesophageal atrial stimulation with 1:1 AV conduction at a rate of 200 beats min-1 and prevented by pharmacological depression of AV node. The not particularly high ventricular rate at which VF occurred could suggest that in hypertrophic cardiomyopathy a major role in favouring VF induction is played by the electrophysiological properties of the myocardium and that sudden death can occur as a consequence of different atrial tachyarrhythmias.

Adolescent↗
PubMed1985

Effect of adenosine and adenosine-5'-triphosphate on atrioventricular conduction in patients.

This study was carried out to further elucidate the effects of adenosine and adenosine-5'-triphosphate (ATP) on atrioventricular (AV) conduction in patients. Adenosine (0.24 mg/kg) and ATP (0.28 mg/kg) were administered intravenously to 37 patients undergoing intracardiac electrophysiologic evaluation. Both adenosine and ATP depressed AV conduction by lengthening the atrial to His bundle (AH) interval. The effects of adenosine and ATP after rapid intravenous bolus administration were fast in onset (15 +/- 0.5 and 15 +/- 1.5 s, respectively), but transient in duration (10.5 +/- 0.5 s for ATP and 17 +/- 3 s for adenosine). Although muscarinic blockade with 0.04 mg/kg atropine shortened the AH interval from a control value of 123 +/- 12 to 74 +/- 4 ms, it did not modify the effects of adenosine or ATP, or both (that is, latency and duration of the effects were not significantly different from before atropine administration). In contrast, aminophylline, a competitive antagonist of adenosine, completely prevented the effects of adenosine and ATP. Aminophylline alone also shortened the AH interval from a control value of 98 +/- 9 to 74 +/- 9 ms. This decrease was blocked by propranolol (0.1 mg/kg), whereas propranolol did not influence the ability of aminophylline to antagonize the effects of adenosine or ATP, or both. Thus, the catecholamines released by aminophylline are unlikely to account for the ability of aminophylline to antagonize the effects of adenosine and ATP. In conclusion, these findings indicate that intravenously administered adenosine and ATP are equally effective in producing AV block that is antagonized by aminophylline but not by atropine.

Adenosine↗
PubMed1979

Electrophysiologic properties of intravenous Tenormine in man.

The acute electrophysiologic effects of intravenous Tenormine (0.1 mg/kg body weight), a new cardioselective beta-adrenoreceptor blocking drug, were studied in 18 subjects with estimated normal impulse formation and conduction. The most significant (P less than 0.01) effects were sinus cycle lengthening, depression of intranodal conduction and prolongation of AV node refractory periods. Sinus node recovery time, sinoatrial conduction time and atrial refractory periods were only slightly prolonged (P less than 0.05). Intraatrial conduction and infra-His conduction were unchanged. These properties are compared with those of the most commonly employed beta-blocking agents. The clinical implications are discussed.

Acetamides↗
PubMed1978

Electrophysiological properties of intravenous metoprolol in man.

Electrophysiological changes produced by intravenous (0.1 mg/kg) metoprolol, a new selective beta 1-blocking agent devoid of intrinsic activity, were studied in 16 subjects with estimated normal impulse formation and conduction. The most important effects were sinus bradycardia, mild increase of sinoatrial conduction time, depression of intranodal conduction, and prolongation of AV node refractory periods. Sinus node recovery time and atrial refractory periods were unmodified. Infranodal conduction and the refractory periods of the His-Purkinje system, as well as of the bundle-branches, were unchanged. These effects are compared with those observed after intravenous propranolol, pindolol, and oxprenolol.

Adult↗
PubMed1978

Chronic juvenile AV nodal dysfunction associated with mitral valve prolapse.

The prevalence of atrioventricular (AV) conduction disturbances amongst patients with mitral valve prolapse is higher than may be expected by chance, thus implying the existence of a true association. The main clinical and electrophysiologic findings in 4 patients with mitral valve prolapse showing chronic AV conduction disturbances are presented. Supra-His localization, mild and variable degree of impairment, regression upon Atropine administration, apparent absence of progression, are common features of these disturbances. The most likely mechanisms considered are an AV node developmental abnormality or an AV nodal artery running in contact with the border of the mitral annulus and thus impaired by the abnormal dynamics of the mitral valve.

Adolescent↗
PubMed1977

Effects of prindolol on impulse formation and conduction in man.

Electrophysiologic changes produced by intravenous administration of 0.6 mg Prindolol were studied in 16 subjects with normal impulse formation and conduction. The most important changes were: sinus bradycardia, prolongation of atrial refractory periods, depression of intranodal conduction and prolongation of A-V node refractory periods. Sinus node recovery time was unchanged, and sinoatrial conduction time was only slightly increased. Intraventricular conduction time and the refractory period of the His-Purkinje system and of the bundle branches were unchanged.

Atrioventricular Node↗
PubMed1977

Electrophysiologic properties of intravenous oxprenolol in man.

Electrophysiologic modifications produced by intravenous administration of 0.1 mg/Kg Oxprenolol were studied in 16 subjects with estimated normal impulse formation and conduction. Significant effects were sinus bradycardia, mild increase of sino-atrial conduction time, depression of intranodal conduction and prolongation of A-V node refractory periods. Sinus node recovery time and atrial refractory periods were unchanged. Infranodal conduction and the refractory periods of the His-Purkinje system, as well as of the bundle branches, were unchanged. These effects are compared with those observed after intravenous Propranolol and Prindolol.

Adult↗
PubMed1977

Electrophysiologic evaluation of intravenous bunaphtine in man.

The acute electrophysiologic effects of intravenous Bunaphtine 1,5 mg/kg body weight, a new antiarrhythmic drug, were studied in 19 subjects with estimated normal impulse formation and conduction. Significant effects were sinus bradycardia, prolongation of atrial refractory periods, depression of intranodal and infranodal conduction and prolongation of His-Purkinje system refractory periods. These properties are compared with those of amiodarone and quinidine and form the basis for a correct use of Bunaphtine in the management of arrhythmias.

Adult↗