Search PubMed⌕ Search

Biomedical subjects

B Belhassen

Publications and source records attributed to B Belhassen.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1995

Treatment with beta-adrenergic blocking agents after myocardial infarction: from randomized trials to clinical practice.

OBJECTIVES: Our aim was to determine the percent of patients with myocardial infarction who are treated with beta-adrenergic blocking agents in dosages proved to be effective in preventing death after a heart attack. BACKGROUND: In the prospective randomized trials showing that beta-blocker treatment improves survival rates after myocardial infarction, relatively high dosages of these agents were used. However, it is not known whether these dosages are used in current clinical practice. METHODS: In a retrospective analysis of clinical data from 606 consecutive survivors of myocardial infarction at four university hospitals in three countries, we assessed the number of infarct survivors receiving prospectively defined "effective dosages" of beta-blockers. We defined these dosages as those that demonstrated improved survival rates of infarct survivors who received active drug in large, prospective, double-blind, placebo-controlled trials. RESULTS: Only 58% of infarct survivors with no contraindications to beta-blockers received these drugs at the time of hospital discharge, and only 11% received dosages equivalent to > 50% of the effective dosages. Independent predictors of failure to prescribe beta-blockers to infarct survivors without contraindications to these drugs were the use of diuretic agents, transient heart failure, impaired left ventricular function and increased patient age. Among patients receiving beta-blockers, only the use of propranolol predicted prescription of a low beta-blocker dosage. CONCLUSIONS: Failure to prescribe beta-blockers after myocardial infarction is common but in most cases is not due to clear contraindications. Many patients not receiving beta-blockers belong to subgroups that would derive the greatest benefit from such treatment. Finally, even when beta-blockers are prescribed, the dosages used are considerably lower than those proved to be effective in preventing death after myocardial infarction.

Adrenergic beta-Antagonists↗
PubMed1995

Successful radiofrequency ablation in a 3-month-old baby with permanent junctional reciprocating tachycardia: a new era in the treatment of incessant life-threatening arrhythmias in infants.

We report our experience in treating a 3-month-old baby with accessory atrioventricular pathway by radiofrequency (RF) ablation. The baby was discovered to have incessant supraventricular tachycardia at 4 weeks of age. At that time, two-dimensional echocardiography showed dilated cardiomyopathy. Multiple direct current shocks and multipharmaceutical treatment failed to restore sinus rhythm. Electrophysiology study showed the presence of posteroseptal accessory pathway. Immediately after delivery of two RF pulses, successful ablation of the accessory pathway and complete atrioventricular (AV) block with good junctional escape rhythm were observed. Normal rhythm and AV conduction subsequently returned and all medical treatment was discontinued. To our best knowledge, this is the first case of successful treatment with RF ablation in early infancy.

Catheter Ablation↗
PubMed1994

Should electrophysiological studies be performed in asymptomatic patients following myocardial infarction? A pragmatic approach.

We analyze the arguments commonly afforded by advocates of electrophysiological evaluation for patients with recent myocardial infarction. These arguments are: (1) electrophysiological evaluation is useful for risk stratification of infarct survivors; and (2) it may be used for guiding drug therapy or to identify a group of asymptomatic patients who will benefit from implantation of an automatic cardioverter defibrillator. A positive electrophysiological study is apparently the single best predictor of future arrhythmic events in infarct survivors. However, several noninvasive tests combined may provide just as valuable information. Therefore, electrophysiological evaluation should not be advised, to the majority of infarct survivors, for the mere purpose of risk stratification. Nevertheless, electrophysiological evaluation may be proposed to patients with impaired left ventricular function or high grade ventricular arrhythmias. Patients without inducible arrhythmias have a good prognosis and may be spared the risk of long-term treatment with antiarrhythmic drugs. However, before proceeding with invasive electrophysiological evaluation, both physician and patient should ask themselves if they are willing to go ahead with defibrillator implantation in case sustained monomorphic ventricular tachycardia is induced.

Anti-Arrhythmia Agents↗
PubMed1994

Transvenous implantable cardiovascular defibrillator lead system: experience in 28 patients.

Morbidity and mortality following Automatic Implantable Cardioverter Defibrillation (AICD) is mostly related to thoracotomy performed during placement of epicardial leads. From July 1991 to January 1994, a transvenous lead system (TLS) (Endotak C; CPI) was implanted in 28 patients (24 males, 4 females, age 15-76 years) who suffered from life threatening ventricular tachyarrhythmias. Twenty four patients had a previous MI, mean LVEF was 26% (14-65%), two had mitral valve prolapse (one with prolonged QT), one had hypertrophic and another had dilated cardiomyopathy. The implantation procedure was performed in the operating room (n = 26) or in the Cath lab. (n = 2). Nineteen (out of the 28) patients were treated with Amiodarome before implantation (5 out of 7 had LVEF < 30%). A satisfactory defibrillation threshold (DFT) was achieved using Endotak lead alone in 22 (79%) patients. These patients had LVEF between 10% to 65% (less than 30% in three patients). In six patients the DFT was measured as lower than 20 J, and a subcutaneous patch was added (LVEF 12-38%, 4 patients with Amiodarome therapy). The implanted devices were all from CPI: 1600 (n = 5), PRX (n = 7), P2 (n = 15), PRX II (n = 1). During a 1-32 months of follow-up one patient died from severe CHF. The implanted device operated in 9/28 patients. The only complication related to implantation was infection at the pocket site (n = 2), which responded to antibiotic therapy in one patient, but required device explantation in another patient. The device was reimplanted in that patient three month later, with no further complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[Radiofrequency ablation of idiopathic ventricular tachycardia].

Ablation by radiofrequency has recently come into use to treat cardiac arrhythmias, mostly supraventricular tachycardia. We describe 2 males aged 14 and 24, respectively, with idiopathic ventricular tachycardia. They underwent endocardial mapping and the exit points of the tachycardia were identified. In 1 of them tachycardia originated in the left ventricle, and the other in the outflow tract of the right ventricle. Radiofrequency ablation of the arrhythmia was successful in both.

Adolescent↗
PubMed1993

Idiopathic ventricular tachycardia and fibrillation.

Important data have recently been added to our understanding of sustained ventricular tachyarrhythmias occurring in the absence of demonstrable heart disease. Idiopathic ventricular tachycardia (VT) is usually of monomorphic configuration and can be classified according to its site of origin as either right monomorphic (70% of all idiopathic VTs) or left monomorphic VT. Several physiopathological types of monomorphic VT can be presently individualized, according to their mode of presentation, their relationship to adrenergic stress, or their response to various drugs. The long-term prognosis is usually good. Idiopathic polymorphic VT is a much rarer type of arrhythmia with a less favorable prognosis. Idiopathic ventricular fibrillation may represent an underestimated cause of sudden cardiac death in ostensibly healty patients. A high incidence of inducibility of sustained polymorphic VT with programmed ventricular stimulation has been found by our group, but not by others. Long-term prognosis on Class IA antiarrhythmic medications that are highly effective at electrophysiologic study appears excellent.

Electrophysiology↗
PubMed1992

Clinical and electrophysiologic effects of magnesium sulfate on paroxysmal supraventricular tachycardia and comparison with adenosine triphosphate.

Electrophysiologic studies have shown that intravenous magnesium sulfate prolongs atrioventricular (AV) nodal conduction and refractoriness and thus could play a role in the management of patients with paroxysmal AV reentrant supraventricular tachycardia (SVT). The present study evaluates the clinical and electrophysiologic effects of intravenous magnesium sulfate in patients with SVT and compares them with those of adenosine triphosphate (ATP), one of the most potent drugs in the treatment of this arrhythmia. Patients with inducible sustained SVT were treated with ATP (10 or 20 mg) and magnesium sulfate (2 g over 15 seconds) during electrophysiologic study. If the tachycardia failed to terminate by the sixth minute, an additional 2 g dose of magnesium was given. ATP (10 or 20 mg) was significantly better than magnesium for terminating induced tachycardias (14 of 14 vs 6 of 14, p less than 0.0001). Arrhythmia termination with ATP was due to anterograde AV nodal blockade in all but 1 patient who developed retrograde block over an accessory pathway with decremental conduction. Arrhythmia termination by magnesium was due to retrograde block over an accessory pathway in 3 patients (including the patient with accessory pathway exhibiting decremental conduction), anterograde AV nodal conduction block in 2 patients and premature ventricular complexes in 1 patient. During induced tachycardias, only AH intervals were prolonged by ATP, whereas magnesium significantly prolonged AH and QRS intervals. Short-lasting side effects (chest pain, flushing, nausea) occurred after both drugs were administered but were more severe after magnesium.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1992

Deterioration of ventricular tachycardia to ventricular fibrillation after rapid intravenous administration of magnesium sulfate.

We report the case of a patient who had development of ventricular fibrillation following rapid intravenous administration of magnesium sulfate (2 g over 5 s) for treatment of sustained monomorphic ventricular tachycardia. Initial slowing of the tachycardia was followed by gradual widening of QRS complexes and electrical alternans, leading to ventricular fibrillation within 3 min of magnesium administration.

Aged↗