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Biomedical subjects

B Belhassen

Publications and source records attributed to B Belhassen.

At least 19 recordsLinked to original sources
PubMed2000

Simplified "ATP test" for noninvasive diagnosis of dual AV nodal physiology and assessment of results of slow pathway ablation in patients with AV nodal reentrant tachycardia.

INTRODUCTION: We recently reported that administration of adenosine triphosphate (ATP) during sinus rhythm identifies dual AV nodal physiology (DAVNP) in 76% of patients with inducible sustained AV nodal reentrant tachycardia (AVNRT) at electrophysiologic (EP) study. In that report, however, the ATP test was considered positive for DAVNP only when the results were reproducible at a given dose of ATP. The aim of the present study was to assess the value of a simplified ATP test for noninvasive diagnosis of DAVNP and abolition or modification of the slow pathway (SP) after radiofrequency ablation (RFA) in patients with inducible sustained AVNRT. METHODS AND RESULTS: The value of a single dose of ATP was studied in 105 patients with inducible sustained AVNRT and in 31 control patients before placement of EP catheters in the cardiac chambers. ATP (10 to 60 mg, in 10-mg increments) was injected during sinus rhythm until ECG signs of DAVNP (> or = 50 msec increase or decrease in PR interval in two consecutive beats, or occurrence of > or = 1 AV nodal echo beat) or > or = second-degree AV block was observed. DAVNP was observed in only 1 (3.2%) control patient. The test could be completed in 96 study patients. DAVNP was found by ATP test in 72 (75%) patients, whereas it was diagnosed by EP criteria in 82 (85%) patients. DAVNP by ATP test disappeared in 27 (96%) of 28 patients who underwent SP abolition and in 18 (60%) of 30 patients who underwent SP modification. In the 12 patients with persistent DAVNP determined by ATP test after SP modification, the number of beats conducted over the SP was significantly reduced (from 6.3+/-3.3 to 2.5+/-2.2 beats; P = 0.002). CONCLUSION: A single administration of ATP during sinus rhythm (at a given dose) enables noninvasive diagnosis of DAVNP in a high percentage of patients with inducible AVNRT and reliably confirms the results of RFA of the SP.

Adenosine Triphosphate↗
PubMed2000

Arrhythmias in the congenital long QT syndrome: how often is torsade de pointes pause dependent?

OBJECTIVE: To determine the frequency and predictors of pause dependent torsade de pointes among patients with the congenital long QT syndrome and spontaneous ventricular tachyarrhythmias. DESIGN: The literature on the "congenital long QT" was reviewed. Articles with illustrations demonstrating the onset of spontaneous polymorphic ventricular arrhythmias in the absence of arrhythmogenic drugs were included. RESULTS: Illustrations of 62 spontaneous episodes of torsade de pointes among patients with congenital long QT syndrome were found in the literature. The majority (74%) of documented arrhythmias were "pause dependent"; 82% of these pauses were longer than the basic cycle length by > 100 ms. Age and sex correlated with the mode of arrhythmia initiation. Arrhythmias in infants (</= 3 years old) were not pause dependent, while female sex correlated with pause dependent torsade. Using multivariate analysis, age was the only independent predictor of the mode of onset of torsade de pointes. CONCLUSION: Available data suggest that the majority of spontaneous arrhythmias in the congenital long QT syndrome are pause dependent. Torsade de pointes that is not preceded by pauses appears to be limited to patient subgroups with severe forms of the disease, like symptomatic infants. These findings have important implications regarding the use of cardiac pacing for arrhythmia prevention.

Adult↗
PubMed2000

Prevalence of the Brugada sign in idiopathic ventricular fibrillation and healthy controls.

OBJECTIVE: To determine the prevalence of the Brugada sign (right bundle branch block with ST elevation in V1-V3) in idiopathic ventricular fibrillation and in an age matched healthy population. DESIGN: ECGs from 39 consecutive patients with idiopathic ventricular fibrillation and 592 healthy controls were reviewed. They were classified as definite, questionable, and no Brugada sign (according to predetermined criteria) by four investigators blinded to the subjects' status. RESULTS: Eight patients (21%) with idiopathic ventricular fibrillation but none of the 592 controls had a definite Brugada sign (p < 0.005). Thus the estimated 95% confidence limits for the prevalence of a definite Brugada sign among healthy controls was less than 0.5%. A questionable Brugada sign was seen in two patients with idiopathic ventricular fibrillation (5%) but also in five controls (1%) (p < 0.05). Normal ECGs were found following resuscitation and during long term follow up in 31 patients with idiopathic ventricular fibrillation (79%). Patients with idiopathic ventricular fibrillation and a normal ECG and those with the Brugada syndrome were of similar age and had similar spontaneous and inducible arrhythmias. However, the two groups differed in terms of sex, family history, and the incidence of sleep related ventricular fibrillation. CONCLUSIONS: A definite Brugada sign is a specific marker of arrhythmic risk. However, less than obvious ECG abnormalities have little diagnostic value, as a "questionable" Brugada sign was observed in 1% of healthy controls. In this series of consecutive patients with idiopathic ventricular fibrillation, most had normal ECGs.

Adolescent↗
PubMed1999

Long-term follow-up of patients with long-QT syndrome treated with beta-blockers and continuous pacing.

BACKGROUND: The long-QT syndrome is associated with sudden cardiac death. Combination of beta-blocker and pacing therapy has been proposed for treatment of drug-resistant patients. The purpose of this study was to summarize our long-term experience with combined therapy in patients with long-QT syndrome. METHODS AND RESULTS: A total of 37 patients with idiopathic long-QT syndrome were treated with combined therapy consisting of continuous cardiac pacing and maximally tolerated beta-blocker therapy and followed up for 6.3+/-4. 6 years (mean+/-SD). The group consisted of 32 female and 5 male patients with a mean age of 31.6 years. The mean paced rate was 82+/-7 bpm (range, 60 to 100 bpm). On follow-up, recurrent symptoms caused by pacemaker malfunction were documented in 3 patients. Four patients died during the follow-up period: 2 adolescents stopped beta-blocker therapy, 1 patient died suddenly while treated with combined therapy, and 1 patient died of unrelated causes. In addition, 3 patients had resuscitated cardiac arrest while on combined therapy, and 1 patient had repeated, appropriate implantable cardioverter-defibrillator discharges on follow-up. CONCLUSIONS: Because 28 of 37 patients remain without symptoms with beta-blocker therapy and continuous pacing, combined therapy appears to provide reasonable, long-term control for this high-risk group. However, the incidence of sudden death and aborted sudden death (24% in all patients and 17% in compliant patients) strongly suggests the use of a "back-up" defibrillator, particularly in noncompliant adolescent patients. Implantable cardioverter-defibrillator therapy, however, may be associated with recurrent shocks in susceptible patients.

Adolescent↗
PubMed1999

Catheter-induced mechanical trauma to accessory pathways during radiofrequency ablation: incidence, predictors and clinical implications.

OBJECTIVES: To evaluate the incidence, predictors and clinical implications of nonintentionally catheter-induced mechanical trauma to accessory pathways during radiofrequency ablation procedures. BACKGROUND: Data on the incidence and significance of catheter-induced trauma to accessory pathways are scarce. METHODS: Consecutive patients (n = 381) undergoing radiofrequency ablation of accessory pathways at two different institutions were closely monitored for appearance of mechanical block of accessory pathways during catheter manipulation. RESULTS: Mechanical trauma to accessory pathways was observed in 37 (9.7%) patients. According to a multivariate analysis, the only independent variable associated with this phenomenon was the anatomical pathway location (p = 0.0001). The incidence of trauma of either right anteroseptal (38.5%) or right atriofascicular pathways (33.3%) was significantly greater than that of pathways (< or =10%) at all remaining locations (p < 0.0001). The duration of conduction block observed ranged from < or =1 min to >30 min in 19% and 35% of patients, respectively. "Immediate" application of radiofrequency pulses at sites of mechanical block (<1 min after occurrence) was associated with a 78% long-term success rate at follow-up. This contrasted with a 25% long-term success rate in patients in whom pulses were delivered 30 min after occurrence of block ("delayed pulses"). Finally, in 24% of patients persistent trauma-induced conduction block led to discontinuation of the ablation procedure. CONCLUSIONS: Trauma to accessory pathways is more common than previously recognized and frequently results in prolongation or discontinuation of the ablation procedure and in lower success rates. The only independent predictor of catheter-trauma to accessory pathways is the pathway location.

Adolescent↗
PubMed1999

Atypical AV nodal reentry with bystander accessory pathway: an unusual mechanism of preexcited tachycardia.

We present an unusual mechanism of preexcited tachycardia--atypical AV nodal reentry with bystander AP. It can be differentiated from other preexcited tachycardias by its variable degree of preexcitation (either spontaneous or in response to atrial pacing), higher degree of preexcitation with pacing near the origin of the AP than during tachycardia, inability to preexcite the tachycardia by either late atrial or ventricular premature beats, the presence of nonpreexcited atypical AV nodal reentry tachycardia following successful AP ablation, and by exclusion of atrial tachycardia.

Adolescent↗
PubMed1999

Effects of electrophysiologic-guided therapy with Class IA antiarrhythmic drugs on the long-term outcome of patients with idiopathic ventricular fibrillation with or without the Brugada syndrome.

INTRODUCTION: Implantation of a implantable cardioverter defibrillator (ICD) is viewed universally as the "gold standard" therapy for patients with idiopathic ventricular fibrillation (VF). We sought to study the long-term value of electrophysiologic (EP)-guided therapy with Class IA antiarrhythmic drugs in patients with idiopathic VF with or without the Brugada syndrome. METHODS AND RESULTS: We performed EP studies in 34 consecutive patients who had idiopathic VF with (n = 5) or without (n = 29) the Brugada syndrome. All patients with inducible sustained polymorphic ventricular tachycardia (SPVT) or VF underwent repeated EP evaluation after oral administration of a Class IA antiarrhythmic drug (mainly quinidine). Patients rendered noninducible received this therapy on a long-term basis. SPVT/VF were induced in 27 (79.4%) patients at baseline studies. Class IA drugs effectively prevented induction of SPVT/VF in 26 (96%) patients. Of the 23 patients treated with these medications, no patient died or had a sustained ventricular arrhythmia during a mean follow-up period of 9.1 +/- 5.6 years (7 to 20 years in 15 patients). Two deaths occurred in patients without inducible SPVT/VF at baseline studies who had been treated empirically. CONCLUSION: Our results suggest that EP-guided therapy with Class IA agents is a reasonable, safe, and effective approach for the long-term management of patients with idiopathic VF. A randomized prospective study of EP-guided Class IA therapy in patients with ICDs seems warranted.

Adolescent↗
PubMed1998

Noninvasive diagnosis of dual AV node physiology in patients with AV nodal reentrant tachycardia by administration of adenosine-5'-triphosphate during sinus rhythm.

BACKGROUND: Atrioventricular nodal reentry tachycardia (AVNRT) represents the most commonly encountered type of regular paroxysmal supraventricular tachycardia. This study determined whether administration of adenosine-5'-triphosphate (ATP) during sinus rhythm may be useful in the noninvasive diagnosis of dual AV nodal pathways. METHODS AND RESULTS: During electrophysiological study, we intravenously administered incremental doses of ATP (from 10 to 50 mg) during sinus rhythm to patients with spontaneous and inducible sustained AVNRT (study group, n=42) and to patients with no evidence of dual AV nodal physiology or inducible AVNRT (control group, n=21). Signs suggestive of dual AV node physiology after ATP administration during sinus rhythm ("jump" of AH > or =50 ms between 2 consecutive beats, > or =1 AV nodal echo beat, or initiation of AVNRT) were observed in 32 (76%) of 42 study patients but in only 1 (5%) of the 21 control patients (P<0.001). Similar results were observed when only surface lead recordings (without intracardiac recordings) were evaluated. Signs suggestive of dual AV node physiology by the ATP test were observed in 29 (80.5%) of 36 patients who had electrophysiological demonstration of dual AV node physiology and in 3 (50%) of 6 patients without AV nodal duality (P=NS). Signs suggestive of dual physiology according to the ATP test disappeared in 11 (92%) of the 12 patients who underwent successful slow AV nodal ablation but persisted in 8 (62%) of 13 patients who underwent AV nodal modification. CONCLUSIONS: Administration of ATP during sinus rhythm may be a useful bedside test for identifying patients with dual AV nodal pathways who are prone to AVNRT. This simple test should be considered as a screening test for patients with symptoms suggestive of paroxysmal supraventricular tachycardia but no documented arrhythmias or for patients with documented narrow complex tachycardia of unclear mechanism.

Adenosine Triphosphate↗
PubMed1997

Mode of onset of malignant ventricular arrhythmias in idiopathic ventricular fibrillation.

INTRODUCTION: The mode of onset of malignant ventricular arrhythmias (ventricular tachycardia [VT] or ventricular fibrillation [VF]) has been well described in patients with organic heart disease and in patients with the long QT syndromes. Less is known about the mode of onset of VF in patients with out-of-hospital VF who have no evidence of organic heart disease or identifiable etiology. METHODS AND RESULTS: We reviewed the ECGs of all our patients with idiopathic VF. Documentation of the onset of spontaneous arrhythmias was available for 22 VF episodes in 9 patients (6 men and 3 women; age 41 +/- 16 years). In all instances, spontaneous VF followed a rapid polymorphic VT, which was initiated by premature ventricular complexes (PVCs) with very short coupling intervals. The PVC initiating VF had a coupling interval of 302 +/- 52 msec and a prematurity index of 0.4 +/- 0.07. These PVCs occurred within 40 msec of the peak of the preceding T wave. Pause-dependent arrhythmias were never observed. CONCLUSION: Cardiac arrest among patients with idiopathic VF has a very distinctive mode of onset. Documentation of a polymorphic VT that is not pause dependent is of diagnostic value.

Adult↗
PubMed1995

[Transseptal left heart catheterization: a new application of an old invasive technique].

In this evolving era of balloon mitral valvotomy (BMV), radiofrequency ablation (RF) of left-sided bypass tracts via catheter, and hemodynamic evaluation of aortic mechanical prostheses, there has been renewed interest in transseptal left heart catheterization (TSLHC). In the 3 years 1990-1994, 122 consecutive patients were referred for TSLHC to our institute (which lacks thoracic surgical facilities). 12 patients were excluded; 10 with a LA mass proven by transesophageal echocardiography (TEE), 1 with a vascularized thrombus in the circumflex coronary system and 1 with congenital interruption of the inferior vena cava with azygous continuity. In the remaining 110 cases TSLHC was performed for interventions in 90 cases (82%) of BMV, and for left-sided catheter radiofrequency (RF) ablation in 3 (3%). For diagnostic purposes it was performed in 17 (15%) cases for hemodynamic evaluation of mechanical aortic valve prostheses. Using the Brockenbrough needle, the adult Mullins sheath system (MSS) and single plane fluoroscopy, 100% technical success was achieved. Needle puncture was not needed in 30 (27%) due to direct crossing with the MSS through a stretched foramen ovale. In 2 we had to perform SVC dye injection for better interatrial septum localization. There were no complications when TSLHC was only used for diagnostic procedures. 1 patient had perforation of the LA due to right lower pulmonary vein laceration following septal dilatation. Following stabilization by immediate pericardiocentesis, the patient was transferred for open heart surgery. There were no great vessel perforations, systemic embolization or periprocedural deaths. TSLHC can be performed quite safely with single-plane fluoroscopy without an onsight surgical team, as with an experienced staff this procedure has very low morbidity and mortality.

Cardiac Catheterization↗