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Biomedical subjects

L Tavazzi

Publications and source records attributed to L Tavazzi.

At least 217 records · Page 12Linked to original sources
PubMed1978

[Electrophysiological aspects of ectopic atrial tachycardia (author's transl)].

In 10 patients with supraventricular tachycardia who underwent an electrophysiological study the ectopic atrial origin of the tachycardia could be demonstrated by the intracavitary localization of the earliest depolarized point (six cases in the right atrium and four cases in the left). Vagal stimulation and/or the i.v. infection of ATP induced or increased the degree of AV block during tachycardia; in five cases ATP interrupted the tachycardia. On the basis of their clinical and electrophysiological behavior, the patients were divided into two groups. In the first one (6 patients) tachycardia was persistent, started following late atrial beats with the same morphology of the subsequent and showed a progressive initial rate increase (warm-up phenomenon); programmed atrial stimulation failed to start and interrupt it. In the second group (4 patients) tachycardia was paroxysmal or repetitive, started following early atrial beats and could be induced and interrupted by programmed atrial stimulation. With respect to the electrophysiological characteristics of each group the authors try to define the possible mechanism responsible for the tachycardia (automaticity and micro-reentry).

Adenosine Triphosphate↗
PubMed1977

Favorable effects of hyaluronidase on electrocardiographic evidence of necrosis in patients with acute myocardial infarction.

To evaluate hyaluronidase's effect in reducing post-infarction myocardial necrosis, we randomized 91 patients with anterior infarction to control (45) or to hyaluronidase-treatment (46) groups. A 35-lead precordial electrocardiogram was recorded on admission and seven days later. Hyaluronidase was administered intravenously after the first electrocardiogram and every six hours for 48 hours. QRS-complex changes were analyzed to assess the drug's effect. Precordial sites with ST-segment elevation (larger than or equal to 0.15 mV) on the initial electrocardiogram that retained an R wave were considered vulnerable for the development of electrocardiographic signs of necrosis. The sum of R-wave voltages of vulnerable sites fell more in the control group than in the hyaluronidase group (70.9 +/- 3.6 per cent [+/- 1 S.E.M.] vs 54.2 +/- 5.0 per cent P less than 0.01). Q waves appeared in 59.3 +/- 4.9 per cent of the vulnerable sites in control versus 46.4 +/- 4.9 per cent in hyaluronidase-treated patients (P less than 0.05). Thus, hyaluronidase reduced the frequency of electrocardiographic signs of myocardial necrosis.

Acute Disease↗
PubMed1977

[Junctional reciprocating tachycardia with second degree A-V block (author's transl)].

Two cases of paroxysmal supraventricular tachycardia sustained by an atrioventricular junctional reentry mechanism are presented. During the electrophysiological study it was possible to induce paroxysms of tachycardia showing 3:2 Lucianai-Wenckebach type and 2:1 atrioventricular block. The site of the block, its functional nature and the possible involvement of an anterogradely blocked atrio-nodal or atrio-His accessory pathway in the reentry circuit are discussed.

Adolescent↗
PubMed1976

[Correlations between automaticity and conduction. Considerations in a case of left bundle branch block in phases 3 and 4 (author's transl)].

A case of phase-3 (tachycardia dependent) and phase-4 (bradycardia-dependent) left bundle branch block (LBBB) which illustrates some relationships between automaticity and conduction in the intraventricular conduction system is reported. The observations made were: a) a conspicuous spontaneous variability of the conductivity and block temporal zones in the left bundle branch (LBB), i.e. of the cycle duration determining either normal intraventricular conduction or block in the LBB; b) after isoproterenol, transient shortening of phase-3 block zone and disappearance of phase-4 block zone due to escape beats which rise from the LBB; c) transient change into not rate-dependent LBBB in consequence of catheter LBB injury and gradual successive reappearance of conductivity zone; d) short periods of 2:1 phase-4 LBBB. A coexisting phase-4 block in a LBB fascicle with electrocardiographic pattern not fulfilling the agreed diagnostic criteria for hemiblocks was also demonstrated. This intraventricular conduction defect was also characterized by conspicuous spontaneous variability of the block temporal zones. After isoproterenol, the duration of the cycle decreased where it occurred. After LBB traumatic injury, it lasted not rate-dependent longer than LBBB and no escape beats rising from the LBB injured fascicle appeared. During normal intraventricular conduction the ECG showed "ischemic" alterations in V1-V4 leads of variable degree related to LBB conductivity and block zone duration. Selective coronary angiograms were normal. These findings are discussed in an attempt to clarify the electrophysiological mechanism of rate-dependent intraventricular conduction defects.

Automatism↗