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Biomedical subjects

F Luzza

Publications and source records attributed to F Luzza.

44 records · Page 3Linked to original sources
PubMed1985

Asynchronous intraventricular recovery as a basis for apparent 'supernormality'.

Various mechanisms have been postulated for the supernormal phase of intraventricular conduction where relatively early impulses are conducted with normal intraventricular conduction and relatively late impulses with abnormal intraventricular conduction. The cases presented here illustrate how asynchronous recovery of conducting tissue may result in fortuitous momentary synchrony early on in the recovery phase with asynchronous conduction properties in the later phases of recovery. This will facilitate potential synchronous conduction early on in the cycle which would result in a normal QRS complex, and potential asynchronous conduction in the later phases which would manifest with a bundle branch block QRS complex.

Aged↗
PubMed1985

Sinoatrial block with complicating sinoatrial reciprocation.

This presentation reflects an atypical manifestation of sinoatrial block in a patient with chronic renal failure and hyperkalemia (7.8 mEq/L). An allorhythmic distribution of P-P intervals permits the interpretation of sinoatrial block complicated by sinoatrial reciprocation.

Electrocardiography↗
PubMed1985

[The retriggerable refractory period: a rare cause of apparent sensing malfunctioning in various types of VVI pacemakers].

The retriggerable Refractory Period (RP) is an anti-interference device that causes prolongation of the RP in the presence of rapid false signals. The device starts functioning when a suprathreshold impulse manifests during the second half of the RP of the pacemaker; in such a case the RP itself is retriggered, i.e., re-starts from the moment in which the retrigger occurs. As a consequence, the time during which the pacer cannot be recycled is prolonged. We report a case of unusual pseudo-malfunction caused by the retriggerable RP observed in a patient paced with a Lit 222 Sorin VVI pacemaker. Spontaneous QRS complexes coupled up to 480 ms appeared as not senses, i.e. did not reset the pacemaker, whereas complexes occurring at 510 ms or more from the spike provoked a normal recycling, and complexes coupled at 490-500 ms resulted in partial recycling. This pattern has been interpreted assuming that a spurious signal (probably an afterpotential) occurs shortly after the paced stimulus. Such a signal falls in the retriggerable RP, resulting in prolongation of the RP. Spontaneous QRS, thus, cannot be sensed until 480 ms from the paced impulse. The chest wall stimulation has clarified the principles governing the functioning of the retriggerable RP. When the RP is retriggered three times in the course of a single pacemaker cycle, the pacer varies its mode of functioning, being the pacing rate increased to a value identical to the magnet rate. Furthermore, the RP is extremely prolonged, occupying the 90% of the pacing interval; only impulses occurring during the last 80 ms, thus, are able to reset the PM.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

[Reduction of the threshold of myocardial excitability after an extremely long asystolic pause: late phase of "supernormal excitability?].

A patient with a malfunctioning pacemaker due to lead insulation defect is reported. High voltage stimuli were always effective, while when the pulse amplitude was reduced to 3.8 volt stimuli were uneffective except when occurring after extremely long asystolic pauses. An advanced exit block (up to 7:1) thus occurred. Late lowering of the myocardial threshold of excitability could be explained by slow spontaneous diastolic depolarization occurring in myocardial fibers surrounding the tip of the electrode.

Aged↗
PubMed1984

[Ventricular extrasystole of re-entry originating in the myocardium surrounding a parasystolic focus: a mechanism responsible for the irregularity of the interectopic intervals during parasystole].

We have observed a case of ventricular parasystole in which the ectopic beats occurred often in couplets. The analysis of the interectopic intervals suggests that the first beat of the couplet is parasystolic in origin, whereas the second one is due to a re-entry which takes place in the myocardium surrounding the parasystolic focus. Moreover, our observations lead us to speculate that an occasional supraventricular beat could cause an exit block of the parasystolic focus through a concealed re-entry.

Aged↗
PubMed1983

[Occult ventricular bigeminy. Description of a case with extrasystole variable coupling separated by sinus beats in even or odd numbers].

We have analyzed an electrocardiogram showing many unifocal ventricular extrasystoles with wide variations of the coupling intervals. Ventricular bigeminy was frequent but in many instances more than one sinus beat occurred between two consecutive extrasystoles. In such a case the intervening sinus beats occurred indifferently both in odd and even numbers. Moreover, extrasystoles preceded by an even number of sinus beats had a relatively long coupling interval whereas extrasystoles that followed and odd number of sinus beats showed shorter coupling intervals. An opposite pattern of the coupling interval was observed with the extrasystoles that followed an interpolated premature ventricular depolarization. In such a case the coupling interval was long after an odd number of sinus beats and vice versa. This mechanism may be interpreted as due to concealed ventricular bigeminy caused by a ventricular ectopic focus which is surrounded by two different zones of block: a proximal zone of 2:1 block, and a distal one in which the block occurs irregularly. Unlike what appears in typical concealed bigeminy, characterized by only odd numbers of sinus beats between consecutive extrasystoles the intervening sinus complexes are indifferently in odd and even numbers. The constant relationship between the coupling interval and the number (odd or even) of sinus beats by which the extrasystole is preceded, allows us to recognize the presence of an atypical form of concealed bigeminy.

Aged↗
PubMedDate not supplied

Antibacterial drugs in Crohn's disease.

The evidence of a beneficial role of antibacterial drugs in Crohn's disease is largely empirical. Data accumulate to show that these drugs may well be used as an adjunctive therapy to oral anti-inflammatory drugs. Circumstantial evidence has also been provided that antibacterial drugs are effective in relieving symptoms related to bacterial overgrowth and when used for specific indications such as perianal lesions.

Anti-Bacterial Agents↗