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Biomedical subjects

A Michelucci

Publications and source records attributed to A Michelucci.

89 records · Page 5Linked to original sources
PubMed1977

[Effects of oxyfedrine on sino-atrial function and on conduction in patients with sinus node and/or atrial dysrhythmias (author's transl)].

The electrophysiological effects of Oxyfedrine on sino-atrial function and on A-V junctional and subjunctional conduction have been studied in 16 patients with sinus node and/or atrial dysrhythmias. The following effects have been observed: --a positive chronotropic effect on the sinus node; --an essentially indirect (rate-dependent) shortening of the Functional and Effective Refractory Periods (FRP and ERP) of the atria without variation of the Intra-Atrial Conduction Time (HRA-LRA). There was no significant shortening of the Maximal Atrial Latency (max AL), of the Corrected Sinus Node Recovery Time (CSNRT) and of the Sino-Atrial Conduction Time (SACT). The limits of Zones I, II, III of the sinus node response to atrial extra-stimuli were reduced with no significant change in their duration, expressed as percentage of the Sinus Cycle Length (SCL); --an improvement in the A-V junctional conduction (shortening of the A-H interval for comparable cycle lengths) due to a relatively shortened A-V junctional ERP. The use of the drug in patients with sinus bradycardia and/or atrial dysrhythmias and conduction disturbances, is proposed.

Adult↗
PubMed1976

[An evaluation of right ventricular compliance (author's transl)].

Right ventricular "compliance" and "stiffness" in a casuistry of 51 patients were studied with varied pressure loads, using the "specific compliance" (SC) index proposed by Smith and coll. (1974) for the left ventricle and the "stiffness" constant proposed by Gaasch and coll. (1972, 1975). The pateints were subdivided according to a hemodynamic criterion, on the basis of telediastolic volume values (RVEDV) and telediastolic pressure (RVEDP) of the right ventricle. The average "specific compliance" was 0.1203 +/- 0.0283 in patients with RVEDP below or equal to 7 mmHg and 0.0517 +/- 0.0269 in those with RVEDP greater than 7 mmHg. In these two groups, the respective average values of the "stiffness" constant were 0.0136 +/- 0.0007 and 0.0210 +/- 0.0016. Comparison of the groups showed a significant statistical difference among the indices. In the subdivision into groups with telediastolic volume, the average SC values were respectively 0.0832 +/- 0.0083 in the patients with RVEDV below 150 ml/m2; 0.1131 +/- 0.0375 in the patients with RVEDV between 150 and 200 ml/m2; 0.0650 +/- 0.0132 in the patients with RVEDV above 200 ml/m2. None of the three groups demonstrated statistically significant differences. In the telediastolic volume groups, the average values of the "stiffness constant" were respectively: 0.0235 +/- 0.0020; 0.149 +/- 0.0007; 0.0117 +/- 0.0006. A comparison of the three groups showed statistically significant differences for this index. The authors consider that in pressure overloading of the right ventricle with different etiopathogenesis of "stiffness" and "compliance" indices, based on the measuring of volume and pressure, are unable to give absolute measuring of the physical characteristics of the ventricular walls. Thus, recourse to methods that can evaluate wall "stress" are necessary. However, the parametres considered are quite useful for indicating the variations of ventricular distensibility in homogenous casuistries and are therefore comparable.

Adult↗
PubMedDate not supplied

[Rational bases for the therapy of supraventricular tachycardias and their management].

Supraventricular arrhythmias are frequently encountered in clinical practice. Despite their common anatomical origin above the division of His' bundle into bundle branches, these arrhythmias have profoundly different electrophysiological mechanisms, clinical significances and responses to treatment. Although 12-lead surface ECG usually enables correct identification, facilitating treatment choice in the emergency room, electrophysiologic testing to determine the site of origin and the pathway of the arrhythmia may be necessary for the management of definitive treatment. Drug therapy is efficient for conversion to sinus treatment in 80-90% of patients with new onset arrhythmias. Class Ic antiarrhythmics (propafenone and flecainide) are particularly useful for atrial fibrillation, while adenosine and verapamil are the drugs of choice for reentry tachycardias. Atrial flutter is a noteworthy exception, and DC shock is often required to terminate the arrhythmia. The results of antiarrhythmic therapy for long term prevention of recurrences are often disappointing. Recent surgical and technological developments, in particular transcatheter ablation procedures, now allow definitive resolution of most reentrant arrhythmias, including preexcitation syndrome. This report discusses current concepts regarding the management of supraventricular arrhythmias.

Anti-Arrhythmia Agents↗