Long Qt Syndrome And Torsade De Pointes Tachycardia

A torsade de pointes tachycardia is a specific form of the polymorphic VT in patients with a prolonged QT interval. Characteristic are fast, irregular QRS complexes that undulate to the ECG baseline. This arrhythmia can end spontaneously or degenerate into ventricular fibrillation. A torsades de pointes tachycardia caused significant hemodynamic disturbances and is often fatal. The diagnosis results from the ECG. The therapy consists of the administration of magnesium i.v., measures to shorten the QT interval and a Gleichstromkardioversion when the VT has gone into ventricular fibrillation.

The for torsades de pointes tachycardia responsible long QT interval may be induced congenital or drugs. The prolongation of the QT interval predisposes to an arrhythmia. This is done by a prolonged repolarization, producing early afterdepolarisations and a different regional spread of refractoriness.

A torsade de pointes tachycardia is a specific form of the polymorphic VT in patients with a prolonged QT interval. Characteristic are fast, irregular QRS complexes that undulate to the ECG baseline. This arrhythmia can end spontaneously or degenerate into ventricular fibrillation. A torsades de pointes tachycardia caused significant hemodynamic disturbances and is often fatal. The diagnosis results from the ECG. The therapy consists of the administration of magnesium i.v., measures to shorten the QT interval and a Gleichstromkardioversion when the VT has gone into ventricular fibrillation. The for torsades de pointes tachycardia responsible long QT interval may be induced congenital or drugs. The prolongation of the QT interval predisposes to an arrhythmia. This is done by a prolonged repolarization, producing early afterdepolarisations and a different regional spread of refractoriness. Congenital long QT syndrome have been described at least 10 different forms of congenital long QT syndrome. Most cases are among the first 3 sub-groups: Long QT syndrome type 1 (LQT1) caused by a mutation-related dysfunction of the gene KCNQ1 encoding the adrenergic-sensitive cardiac IKs potassium channel. Long QT syndrome type 2 (LQT2) caused by a mutation-related dysfunction of the gene HERG encoding another cardiac Kaliumanal (IKr). Long QT syndrome type 3 (LQT3): caused by a mutation in the gene SCN5A, which prevents the rapid inactivation of the cardiac sodium channel (INa). These forms are autosomal dominant trait with incomplete penetrance and designated in the past as Romano-Ward syndrome. Rare patients have two abnormal copies of the genetic abnormality (especially LQT1). Then, the disease is associated with congenital deafness and was referred to in the past as Jervell and Lange-Nielsen syndrome. Patients with long QT syndrome are prone to recurrent syncope due to torsades de pointes tachycardia and sudden cardiac death due vonTorsade de pointes tachycardias that degenerate into ventricular fibrillation. Drug-induced long QT syndrome More often arises torsades de pointes VT by taking medication, usually antiarrhythmic agents of Class Ia, Ic or III. Other medications that can cause torsades de pointes VT are tricyclic antidepressants, phenothiazines and certain antivirals and antifungals (current list under s. Www.torsades.org). Symptoms and discomfort patients often suffer from syncope because the underlying heart rate of 200-250 beats / min insufficiently supplied with blood the body. Patients who are conscious, often complain of palpitations. In some cases, long QT interval is not discovered until after resuscitation. Diagnostic ECG Diagnosis is from the ECG. Here, a wave-shaped QRS axis points. The polarity of the complexes rotates about the ECG baseline (torsades de pointes tachycardia.). The ECG shows image between episodes a long QT interval on the frequency correction (QTc). The normal QT interval is approximately 0.44 seconds, but varies from person to person and is gender-dependent. The family history may indicate a congenital syndrome. Torsades de pointes tachycardia. Clinical calculator: QT interval correction (ECG) treatment usually not synchronized Gleichstromkardioversion Sometimes magnesium sulfate (MgSO4) i.v. An acute episode, wherein the prolonged QT interval indicates hemodynamic effects will, starting with 100 Joules, treated with a non-synchronized cardioversion. As a rule, however, the torsades de pointes tachycardia occurs shortly thereafter again. Frequently, the administration of magnesium sulphate (MgSO4) 2 g i.v. successfully over one to two minutes. this shows no effect, 5-10 minutes later, a second bolus is given. In patients without renal insufficiency, a magnesium infusion of 3-20 mg / min can be helpful. Lidocaine (a Class Ib antiarrhythmic) shortens the QT interval and may be effective especially in a drug-induced torsade de pointes tachycardia. Antiarrhythmics of classes Ia, Ic and III should be avoided. In a drug-induced torsade de pointes tachycardia the drug is discontinued. As long as the drug is not yet completely broken down, require patients with frequent or long torsades de pointes episodes therapy to shorten the QT interval. Since an increase in heart rate shortens the QT interval, a temporary stimulation, isoproterenol suitable i.v. or a combination of both. long-term therapy is needed for patients with congenital long QT syndrome. For this purpose, are beta-blockers, permanent pacemakers, implantable Kardioverterdefibrillatoren (ICD) or a combination of these options. ECG monitoring for family members are advisable. Patients with congenital long QT syndrome should avoid drugs that prolong the QT interval strictly and patients with symptoms that occur by physical exertion (usually LQT1 or LQT2), should avoid these. Treatment options include beta-blockers, pacemaker to maintain faster heart rates (whereby the QT interval is shortened) or ICD, alone or in combination. Current guidelines recommend ICD for patients who were revived after cardiac arrest and those in which despite treatment with beta-blockers syncope. Summary for torsades de pointes tachycardia responsible long QT interval may be induced congenital or drugs. Immediate treatment of torsades consists of non-synchronized cardioversion, starting with 100 joules, although some patients on MgSO4 2 g iv react for 1 to 2 minutes. In patients with congenital long QT syndrome long-term therapy with beta-blockers, permanent pacemakers, ICD or a combination of these options is required. ECG monitoring for family members are advisable.

Health Life Media Team

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