Biomedical subjects
Publications and source records attributed to P Mélon.
Arrhythmogenic right ventricular dysplasia is an unfrequent disease that associates ventricular tachycardia with left bundle branch block morphology and right ventricular fibro-fatty degeneration. The etiology, pathogenesis, criteria for diagnosis and treatment are discussed.
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Paroxysmal atrial fibrillation is one of the most common disorders of cardiac rhythm. It is often a step toward permanent arhythmia, specially if associated with cardiac disease. The management objectives of intermittent arhythmia may be different, as maintenance of sinus rhythm. However, risks of stroke and thrombo-embolism are similar to those for sustained atrial fibrillation and must be carefully assessed. In this article we review the epidemiology, pathophysiology, clinical aspects and current guidelines for treatment and management of paroxysmal atrial fibrillation.
Paroxysmal supraventricular tachycardias are often encountered in young and otherwise healthy patients. They are rarely life threatening even though they may alter the quality of life. In this article, we review the acute treatment of an episod of tachycardia and the prevention of recurrences.
Syncope remains a clinical challenge. Accurate history taking, physical examination and EKG are mainstays of the diagnosis work up. The most important parameter for prognosis and requiring aggressive management is a structural heart disease. Patient without cardiopathy presenting multiple episodes may be candidate for tilt testing and loop EKG recorder.
The Brugada syndrome, a genetically transmitted disease according to an autosomal mode with a variable penetrance, is responsible for sudden death secondary to polymorphic ventricular tachycardia. The diagnosis is based on a typical electrocardiographical paturn that combines a right bundle branch block with ST elevation in the right precordial leads. In high risk patients, the automatic implantable defibrillator has the unique capability to protect against the occurrence of ventricular arrhythmias.
Implantable cardioverter-defibrillator has been used in the primary prevention of sudden cardiac death. We review its indications according to the underlying cardiac disease based on the recommendations of the scientific societies. We briefly discuss the new problem of its utilization in patients with severe heart failure.
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Arrhythmias do not systematically prevent athletic activities. Symptomatic bradyarrhythmias may first require pacemaker implantation. Usually occurring on normal heart, supraventricular tachycardias are benign. When responsible for palpitations, exercise intolerance or syncope, they may benefit from the use of beta-blockers, calcium channel blockers or most frequently radiofrequency catheter ablation. Ventricular arrhythmias with underlying cardiac disease do not allow intense and sustained physical activities. In case of symptomatic ventricular arrhythmias without cardiac disease, the use of beta-blockers, calcium channel blockers or radiofrequency catheter ablation usually permits sport practice.
Atrial fibrillation is a major source of stroke. During the past decade, large trials demonstrated the efficacy of anticoagulation and, to a lesser extent, aspirin in primary and secondary prevention of stroke in high risk patients with atrial fibrillation. In this article we reviewed the results of these studies and we present the current guidelines for the antithrombotic treatment of atrial fibrillation.
Radiofrequency ablation allows the curative treatment of supraventricular tachycardia and some types of ventricular tachycardia. We reviewed the technical modalities of radiofrequency for the different types of supraventricular tachycardia.
We describe two cases of severe bradyarrhythmias (one complete AV dissociation; one sinus bradycardia) observed after the intravenous injection of dipyridamole.
The diagnosis of the cause of a syncope is based, above all, on the basis of a careful clinical history obtained from the patient or from persons who attended one of the episodes of loss of consciousness. It should also include a careful clinical examination comprising an electrocardiogram and, most often, an echocardiogram. The selection of further investigations should be guided by the existence or absence of an underlying cardiac disease. In the presence of a patent cardiac disease, one should first try to detect a disorder of cardiac rhythm (Holter, mini-Holter, possibly invasive electrophysiology); a dysfunction of the autonomic regulation of the cardiovascular system should only be considered in a second step (Tilt table test). The sequence of investigation should be reversed when syncope occurs in a patient without underlying cardiac disorder.
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The identification of a WPW impose to evaluate the potential risk of sudden cardiac death. The risk depends on the duration of the refractory period of the accessory pathway. If the preexcitation disappears when the patient is stressed on a treadmill, there is no risk of sudden death. If it does not, an electrophysiological study will have to be performed to measure the refractory period of the accessory pathway. If a risk of sudden death is present (refractory period < 220 ms), the accessory pathway has to be ablated using radiofrequency.
The endothelium plays a fundamental role in the regulation of the vascular tone. It produces EDRF-NO that dilates the vessels. In endothelial dysfunction, the reduction of EDRF-NO production increases the vasoconstrive effects of endothelin-1 and angiotensin-II. The endothelial dysfunction is part of the coronary artery disease. It can be minimized by angiotensin-converting enzyme inhibitors that block the deleterious effects of angiotensin-II.
Amiodarone is a highly effective antiarrhythmic agent. Its iodine content and tissue accumulation are however responsible for various side effects. In this article, we review the various amiodarone related side effects and propose a monitoring chart for patients treated by this specific agent.
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