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Biomedical subjects

G Oreto

Publications and source records attributed to G Oreto.

At least 37 records · Page 2Linked to original sources
PubMed1999

Paroxysmal supraventricular tachycardia caused by 1:2 atrioventricular conduction in the presence of dual atrioventricular nodal pathways.

One-to-two atrioventricular conduction, ie, the double response to a single sinus or atrial impulse, resulting in two QRS complexes for one P wave, is a rare manifestation of dual atrioventricular (AV) nodal pathways. This report describes the case of a 61-year-old woman with continuous episodes of supraventricular tachycardia caused by independent conduction to the ventricles of sinus impulses over both the fast and the slow AV nodal pathway, giving rise to a ventricular rate that was twice the sinus rate. A wide spectrum of electrocardiographic manifestations of 1:2 AV conduction was observed on the surface electrocardiogram. The diagnosis was suggested by several elements including evidence of dual AV nodal pathways during sinus rhythm and cycle length alternans during tachycardia. The patient underwent successful slow pathway ablation with complete disappearance of symptoms and electrocardiographic manifestations of 1:2 AV conduction.

Atrioventricular Node↗
PubMed1998

Post-ventricular tachycardia P wave change simulating atrial enlargement.

An abnormal P wave was observed in a child affected by prolonged idiopathic ventricular tachycardia (fascicular tachycardia). After sinus rhythm restoration, the P wave was very tall and peaked (0.5 mV in lead II), suggesting a diagnosis of atrial enlargement. No cardiac abnormality, however, was detected by clinical and echocardiographic examination. The P wave abnormality lasted for about 1 month, with progressive voltage and shape normalization. These P wave changes were probably dependent on tachycardia; since the arrhythmia was long-lasting and characterized by atrioventricular dissociation, repetitive atrial contraction against closed atrioventricular valves caused stretching of atrial fibers, resulting in P wave abnormality. This observation suggests that very prolonged ventricular tachycardia may be associated with an electrocardiographic pattern of pseudoatrial enlargement.

Bundle-Branch Block↗
PubMed1997

Inappropriate sinus tachycardia after radiofrequency ablation of para-Hisian accessory pathways.

INTRODUCTION: Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinical significance of IST following RFA of para-Hisian accessory pathways (APs). METHODS AND RESULTS: Twenty-eight patients (pts) with para-Hisian APs underwent RFA. An AP was defined as para-Hisian whenever its atrial and ventricular insertions were associated with a His-bundle potential > or = 0.1 mV. RF current was always delivered at the atrial aspect of the tricuspid annulus, to a site where the His-bundle potential was < 0.15 mV. Time- and frequency-domain analysis of heart rate variability was performed in 22 patients, before and after RFA. Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred. Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure. In 5 of them, IST disappeared spontaneously within 72 hours, whereas in 1 pt beta-blockers were required for 2 months. The atrial potential amplitude (1.217 +/- 0.264 mV vs 0.882 +/- 0.173 mV, P = 0.009) and A/V potential amplitude ratio (2.633 vs 1.686, P = 0.05) were significantly higher in pts who developed IST than in those who did not. A marked decrease in heart rate variability was observed only in pts who developed IST. CONCLUSION: IST is a relatively frequent complication after RFA of para-Hisian APs: it is generally short-lasting and usually does not require any treatment. IST after catheter ablation is likely to depend upon transient parasympathetic denervation of the sinus node.

Adolescent↗
PubMed1997

[Unidirectional block and longitudinal dissociation in an accessory pathway induced by radiofrequency].

This report describes an unusual arrhythmia due to partial damage of an accessory pathway by radiofrequency energy delivered during a catheter ablation procedure. The following phenomena were observed after the first radiofrequency current application: a) manifest anterograde conduction over the Kent bundle was abolished, so that preexcitation disappeared; b) concealed anterograde conduction over the accessory pathway was interrupted, resulting in initiation of orthodromic re-entrant tachycardia by any sinus impulse; c) retrograde conduction through the accessory pathway was impaired, but still present, and a pattern of longitudinal dissociation manifested; this was suggested by alternation of the R-P intervals, that during orthodromic tachycardia were alternatively long and short. Following a second radiofrequency application, the R-P interval during orthodromic tachycardia became markedly prolonged (0.36 sec), to the extent that the pattern mimicked a form of atrial or sinus tachycardia. Retrograde accessory pathway conduction was totally interrupted following a third radiofrequency energy application.

Adult↗
PubMed1996

Manifest and concealed AV nodal reentry in Wenckebach type of AV conduction with AV junctional escape rhythm.

An electrocardiogram was obtained that was characterized by sinus rhythm with progressive prolongation of the PR interval not followed by a blocked sinus impulse. After a critically long PR interval, the QRS complex was followed by a premature P' wave, representing an echo beat, a manifest reentry in the atrioventricular (AV) node. The pause, occasioned by the premature P' wave, was at times interrupted by an AV junctional escape beat, occurring with an escape interval of 1.21-1.24 seconds. On other occasions, however, the escape beat did not manifest on schedule, even though the pause was markedly longer than the escape cycle. This suggested that the manifest reentry was followed by a further concealed reentry, resulting in inapparent discharge of the AV junctional escape pacemaker, whose firing was postponed, thereby allowing the sinus impulse to capture the ventricles.

Aged↗
PubMed1996

Induction of ventricular fibrillation predicts sudden death in patients treated with amiodarone because of ventricular tachyarrhythmias after a myocardial infarction.

OBJECTIVE: To examine the value of programmed electrical stimulation of the heart in predicting sudden death in patients receiving amiodarone to treat ventricular tachyarrhythmias after myocardial infarction. DESIGN: Consecutive patients; retrospective study. SETTING: Referral centre for cardiology, academic hospital. PATIENTS: 106 patients with ventricular tachycardia (n = 77) or ventricular fibrillation (n = 29) late after myocardial infarction. INTERVENTIONS: Programmed electrical stimulation was performed while on amiodarone treatment for at least one month. MEASUREMENTS AND MAIN RESULTS: In 80/106 patients either ventricular fibrillation (n = 15) or sustained monomorphic ventricular tachycardia (n = 65) was induced. After a mean follow up of 50 (SD 40) months (1-144), 11 patients died suddenly and two used their implantable cardioverter debfibrillator. By multivariate analysis two predictors for sudden death were found: (1) inducibility of ventricular fibrillation under amiodarone treatment (P << 0.001), and (2) a left ventricular ejection fraction of < 40% (P < 0.05). The survival rate at one, two, three, and five years was 70%, 62%, 62%, and 40% respectively for patients in whom ventricular fibrillation was induced, and 98%, 96%, 94%, 94% for patients with induced sustained monomorphic ventricular tachycardia. Where there was no sustained arrhythmia, five year survival was 100%. CONCLUSIONS: In patients receiving amiodarone because of life threatening ventricular arrhythmias after myocardial infarction, inducibility of ventricular fibrillation, but not of sustained monomorphic ventricular tachycardia, indicates a high risk of sudden death.

Adult↗
PubMed1996

Wide complex tachycardia with atrioventricular dissociation and QRS morphology identical to that of sinus rhythm: a manifestation of bundle branch reentry.

OBJECTIVE: To determine the features that distinguish bundle branch reentry (BBR) ventricular tachycardia from a supraventricular tachycardia with aberration on the 12 lead electrocardiogram (ECG). PATIENTS: Three patients in whom premature beats (2 cases) or sustained tachycardia (2 cases) showed a QRS configuration identical to that observed during sinus rhythm. INTERVENTIONS: Programmed electrical stimulation. RESULTS: These arrhythmias were ventricular in origin and caused by a BBR mechanism, as suggested by the following data obtained during electrophysiological study: (a) an H-V interval shorter during tachycardia than during sinus rhythm; (b) A-V dissociation; (c) activation of the right bundle branch before activation of the bundle of His. The ECG of all 3 patients showed right bundle branch block with very prolonged QRS duration (0.16 to 0.20 s). Characteristically, all 3 had prolonged H-V interval during sinus rhythm. All patients had had a previous myocardial infarction and had a dilated left ventricle. CONCLUSION: The presence of (a) wide complex extrasystoles or tachycardia with a QRS morphology identical to that of sinus rhythm; (b) A-V dissociation; and (c) a very prolonged QRS duration (0.16 s or more) is suggestive of ventricular tachycardia caused by bundle branch reentry.

Aged↗
PubMed1996

[A comparison between propafenone and hydroquinidine perorally in the treatment of recent-onset atrial fibrillation].

The aim of this study was to assess the effectiveness of propafenone and quinidine to restore sinus rhythm in patients with paroxysmal atrial fibrillation. Eighty consecutive patients with recent onset atrial fibrillation were randomized to one of the following oral treatments: a) propafenone 450 mg as single dose followed by 300 mg t.i.d.; b) hydroquinidine 900 mg/24 hours + digoxin if necessary. Drugs were given for a maximum of three days and withdrawn at the restoration of sinus rhythm. If atrial fibrillation was persistent, the other drug was administered after two days wash out. The two groups did not differ from each other with respect to left atrial size, age and presence of organic heart disease, and kind of cardiopathies between the two groups. Sinus rhythm was restored in 39 patients of group 1 (93%) and 36 of group 2 (95%). In conclusion, oral propafenone is as effective as quinidine in the treatment of paroxysmal atrial fibrillation.

Administration, Oral↗
PubMed1995

[Pseudo AV dissociation caused by interpolated junctional extrasystoles in the presence of a first-degree AV block].

This presentation reports an electrocardiogram showing first degree A-V block with a very prolonged P-R interval of 0.80 sec. On several occasions an arrhythmia occurred, characterized by what looked like an A-V junctional escape rhythm with A-V dissociation. This was suggested by a variable and, at first glance, haphazard relationship between QRS complexes and P waves. Analysis of the tracing suggested that the pattern was due to an interpolated A-V junctional extrasystole, followed by a sinus beat with an inordinately long P-R interval, whose duration was 1.18 sec. This very prolonged A-V conduction time made it difficult to recognize the relationship between P waves and QRS complexes, so that the pattern appeared as an A-V dissociation.

Aged↗
PubMed1994

Supernormal conduction in the left bundle branch.

This report describes a patient with tachycardia-dependent left bundle branch block (LBBB) and atrial extrasystoles, some of which were followed by an unexpectedly narrow QRS complex. His-bundle recordings and premature atrial stimulation were performed to analyze the mechanism underlying the normalized intraventricular conduction of some of the early atrial impulses. The results suggested the presence of supernormal conduction in the left bundle branch (LBB), because: (1) the HV interval was identical in LBBB complexes and in early narrow QRS complexes; (2) during single test stimulation using different paced atrial cycle lengths, there was a well-defined range of H1H2 intervals resulting in normalization of intraventricular conduction; and (3) atrial pacing with a cycle length of 500 msec resulted in alternation between wide and narrow QRS complexes. These findings rule out alternative mechanisms that could explain the unexpectedly normal intraventricular conduction of early impulses.

Bundle-Branch Block↗
PubMed1994

Recurrence rate after accessory pathway ablation.

OBJECTIVE: To evaluate characteristics of patients and accessory pathways as well as additional technical factors involved in the reappearance of accessory pathway conduction after successful ablation. DESIGN: Analysis of recurrences after radiofrequency ablation. SETTING: 163 consecutive patients with 167 accessory pathways. SUBJECTS: 97 men and 66 women with a mean (SD) age of 36 (14) range (11 to 75) years. RESULTS: After a mean (SD) follow up of 14 (7) range (2 to 27) months, conduction recurred in 13 out of 167 (7.8%) accessory pathways. The initial manifestation of recurrence was circus movement tachycardia in 7 patients and reappearance of delta waves on a 12 lead electrocardiogram in 6 patients. The interval to the return of accessory pathway conduction ranged from 3 hours to 90 days. Age, sex, presence of multiple accessory pathways, criteria to determine the target ablation site, number and duration of radiofrequency applications, and cumulative energy did not significantly differ between the groups with recurrence and without. Recurrence was less common with concealed accessory pathways (2/44) than with overt accessory pathways (11/110). The difference was not significant. The only variable to influence the recurrences in this study group was the location of the accessory pathway. Reappearance of conduction through right sided accessory pathways occurred significantly more often than through left sided ones (8/40 v 5/114, P = 0.01). CONCLUSION: After radiofrequency ablation the recurrence rate of accessory pathways is low and there are no predictors of the risk of reappearance of conduction apart from the right sided location of the accessory pathway.

Adolescent↗
PubMed1994

Pseudo-atrioventricular dissociation caused by interpolated ventricular extrasystoles in the presence of dual atrioventricular nodal pathway.

This report describes a patient manifesting with ventricular extrasystoles. The pause occasioned by extrasystoles often is followed by narrow QRS complexes not preceded by P waves, but at times is followed by a sinus P wave. At first glance, the pattern suggests a diagnosis of atrioventricular (A-V) junctional escape complexes. Analysis reveals that ventricular extrasystoles are, in fact, interpolated; the sinus P wave that follows the extrasystole is conducted to the ventricles with a very prolonged P-R interval (up to 0.80 s). The phenomenon is due to the presence of a dual A-V nodal pathway. The sinus impulse that follows the extrasystole is blocked in the fast pathway but may still be conducted to the ventricles through the slow pathway, resulting i a very prolonged P-R interval.

Aged↗
PubMed1994

[Extrasystolic ventricular bigeminy in ventricular tachycardia].

A patient with recent myocardial infarction presented with premature ventricular contractions (PVCs), couplets, and runs of ventricular tachycardia (VT). Two types of ectopic complexes, labeled A and B, were present. Isolated PVCs, as well as the first complex in a couplet, were always type A beats. In contrast, the second beat in a couplet was always a type B beat. Any run of VT was initiated by a type A beat. Monomorphic VT was made only of type B complexes, apart from the first one. Several episodes of VT, however, reflected an alternation of type A and type B complexes with alternating cycle length. This is a manifestation of extrasystolic ventricular bigeminy where any VT impulse (type B) is followed by an extrasystole (type A). In addition, extrasystolic impulses affect the tachycardia, resetting its cycle.

Cardiac Complexes, Premature↗