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Biomedical subjects

V Bonatti

Publications and source records attributed to V Bonatti.

33 records · Page 2Linked to original sources
PubMed1980

[Ischemic and non ischemic electrophysiologic changes during selective coronary arteriography. Their role in the pathogenesis of the electrocardiographic changes and arrhythmias (author's transl)].

The results of a study made in mae recording the right ventricular monophasic action potential (RV MAP) by suction electrocatheter during coronary arteriography (35 cases) are reported. Normally, when no coronary spasm is present, coronary arteriography provokes a prolongation of MAP of the myocardial diffusion of the contrast medium. On the contrary in five cases, in which right coronary spasm occurred, modifications of a clear ischemic pattern were seen: a shortening of the RV MAP phase 2 in two cases; a reduction of the amplitude and rate of the RV MAP phase 0 in one case; both shortening of total duration of RV MAP and changes of its 0 phase in other two cases. The Authors compare these clinical observations with the experimental data and discuss the role of these different electrophysiological alterations in the pathogenesis of the electrocardiographic changes and arrhythmias.

Adult↗
PubMed1979

Preliminary report on electrophysiological effectiveness of creatinol O-phosphate (COP) in human subjects.

N-Methyl-N-(beta-hydroxyethyl) guanidine O-phosphate (creatinol O-phosphate, COP), in previous pharmacological and clinical research showed useful effects on both normal and ischemic heart. These effects can be reconduced to a protective action of COP on cell membrane. In this investigation the possible electrophysiological effects of COP were ascertained in 6 patients, some of whom were free of excitation-conduction disturbances, while others were suffering from sinusal automaticity of A-V conduction alterations. When the nodal A-V conduction was slowed by iatrogenic or functional factors, COP as well as atropine improved it. Thus both COP and atropine act in the non-organic component of the conduction disturbances. The organic component was not affected by both the drugs. The effect of atropine was more evident than that of COP. All the electrophysiological parameters were not affected by COP. This fact allows COP to be administered with absolute safety even in the presence of alterations in the formation and conduction of the stimuli.

Aged↗
PubMed1979

[Recording of monophasic action potentials of the right ventricle in a case of long QT and isolated alternation of the U wave].

Monophasic action potentials (MAP) of the right ventricle were recorded with suction electrodes in a case of long QTU, electrical alternans of the U wave and "torsades de pointe" by hypocalcaemia. Two electrophysiological features were observed:--a notable difference in the duration of MAPs of different zones of the right ventricle;--a change in the length and appearances of phase 3 of the longest MAPs with an inconstant bulge (delayed repolarisation) in the terminal portion of these same MAPs. These changes, which favourise focal reentry phenomena and/or reciprocal conduction are the probable explanation of the pathogenesis of episodes of "torsades de pointe". A reduction in the conductance of potassium associated or related to hypocalcaemia probably explains the second of the two changes.

Aged↗
PubMed1977

[Origin of the left circumflex coronary artery from the right Valsalva sinus. Two cases with clinical and instrumental signs of coronary insufficiency (author's transl)].

Two cases of isolated anomalous origin of the left circumflex coronary artery from the right Valsalva sinus are described. In contrast with all the cases reported in the literature, both our female patients had typical angina; in one case, moreover, in coincidence with the precordial pain there were significant alterations of the repolarization, also caused by stress testing with the bicycle ergometer. On the basis of these findings, the authors believe that in patients with this anomaly the angina might be produced through a sharp decrease in the circumflex coronary artery blood flow correlated with caliber changes of the aorta.

Coronary Angiography↗
PubMed1976

[Effects of Bunaphtine on right atrial and ventricular monophasic action potentials in man. Preliminary note (author's transl)].

Effects of Bunaphtine on right atrial and ventricular monophasic action potentials were investigated in 6 patients using the technique of endocavitary recording with a suction electrode. The authors found that the drug, given intravenously in the usual therapeutic dosages, increases the total duration of MAP both atrial and ventricular, together with quite a proportional ERP prolongation. At ventricular level MAP's increase in correlated to a prevailing and strong increase of phase 3. However, the variations of the MAP's amplitude, its O dv/dt phase and the cardiac specific conduction's alterations (noted only at higher dosages) have been inconstant and poor on the whole. On the basis of these results, the mechanism of the action of the drug is discussed.

Action Potentials↗
PubMed1976

[A study of the mechanism of the action of Bunaphtine recording the myocardial monophasic action potentials in man. Conclusive report (author's transl)].

In this paper the authors conclude their study of the mechanism of the action of Bunaphtine. Both atrial and ventricular MAP were recorded by a suction electrode in 13 patients before and after Bunaphtine (1.5-2 and 2.5 mg/Kg i.v.). With the lower dosages, the drug acts specifically on repolarization: it greatly increases the duration of MAP, together with a proportional ERP prolongation; the ERP/MAP ratio is not changed. With the higher dosages, there is a greater effect on the depolarization velocity (decrease of the O dv/dt phase of MAP) and on the conduction, this last being less evident. At the atrial level there is a conspicous ERP prolongation, with a remarkable increase of ERP/MAP ratio. There is full agreement between these results and those obtained experimentally on the dog and in vitro. Bunaphtine has therefore unquestionable antiarrhythmic properties and it can have a double action mechanism; with higher dosages its action-quinidine-like-is predominant at the atrial level.

Action Potentials↗
PubMed1975

[Junctional bradycardia and junctional non-paroxysmal tachycardia. A study with atrial and His electrogram and influence of neurovegetative system (author's transl)].

Two cases of unusual A-V nodal rythms, very slow junctional bradycardia and junctional non paroxysmal tachycardia, are described. The Authors emphasize the study of the His bundle electrograms, the atrial electrograms and the time of the intrinsecoid deflection for correct diagnosis of these dysrrhythmias. From the results of the clinical and electrofisiological study and neurovegetative responses some conclusions about the mechanism and clinical significance of these arrhythmias are drawn.

Adult↗
PubMedDate not supplied

Early and late postoperative complete heart block in pediatric patients submitted to open-heart surgery for congenital heart disease.

The incidence of complete heart block (CHB) following open-heart surgery for congenital heart disease is about 1%. Most of postoperative CHBs are the consequence of procedures involving the closure of ventricular septal defect; they usually occur immediately after surgery or early in the postoperative period; in few cases they also may occur many months or years after surgery. Early postoperative CHB can be transient or permanent. Permanent pacing is generally not recommended in the former. On the contrary, if CHB persists after at least two weeks of temporary pacing, permanent pacing is needed because the block is usually due to His bundle damage or to trifascicular damage and this is associated with excessive bradycardia and risk of asystole. Late postoperative CHB can be due to the recurrence of previous transient early postoperative CHB or to the progression of postoperative His-Purkinje conduction troubles suggesting trifascicular damage. Permanent pacing is obviously needed in case of documented late postoperative CHB. The prophylactic use of permanent pacing in patients at risk of late postoperative CHB is still a controversial point. Electrophysiologic studies should be performed in such patients. The occurrence of second degree AV block within or below the bundle of His during atrial pacing at rate lower than 200/min can be considered a good marker of impending CHB. In this case prophylactic permanent pacing should be recommended, especially in patients with coexisting problems of troublesome or malignant tachyarrhythmias who have to be treated with antiarrhythmic drug therapy that may favour the progression to CHB.

Adolescent↗