Long QT interval syndrome

DiSegni E, Klein HO, David D, Libhaber C, Kaplinsky E. Overdrive pacing in quinidine syncope and other long QT-interval syndromes. Arch Intern Med 1980 140(8) 1036-40. 

QT interval prolongation. Congenital long QT interval syndrome was confirmed by genetic testing. 

Class lib indications for an ICD (1) Patients optimally managed with New York Heart Association Functional Class I heart failure and nonischemic cardiomyopathy who have a left ventricular ejection fraction <0.35. (2) Syncope of unclear etiology and ECG evidence of Brugada syndrome. (3) Patients with congenital long QT interval syndrome who have reasonable expectation of survival. 

A disease predisposing those affected to severe cardiac arrhythmia. The term long QT syndrome refers to an abnormality found in the electrocardiograms of the patients a long QT interval caused by a prolonged... 

Long (and short) QT interval syndrome Right ventricular dysplasia Hypertrophic cardiomyopathy Idiopathic ventricular fibrillation Infiltrative heart disease Amyloidosis Sarcoidosis Hemochromatosis... 

Comparisons of the incidence of the congenital syndromes show that short QT syndrome is much rarer than long QT syndrome, similar to the findings of short QT intervals compared with long QT intervals in the general population. 

Chest pain. First-degree AV block. Hypotension. Nausea. Long QT interval. Prolonged QRS. Disopyramide increases risk of death in patients with non-life-threatening ventricular arrhythmias. Use cautiously in patients with WoHf-Parkinson-White syndrome or bundle-branch block. 

Torsades de pointes may be inherited or acquired. Patients with specific genetic mutations may have the inherited long QT syndrome, in which the QT interval is prolonged, and these patients are at risk for torsades de pointes. Acquired torsades de pointes maybe caused by numerous drugs (Table 6-13) the list of drugs that are known to cause torsades de pointes continues to expand. 

The congenital form of long QT syndrome is characterized by a prolonged QT interval in the electrocardiogram and TdP [28-30]. Many patients with this syndrome... 

Lande, G., Kyndt, F., Baro, I., Chabannes, D., Boisseau, P., Pony, J.C., Escande, D. and Le Marec, H. (2001) Dynamic analysis of the QT interval in long QT1 syndrome patients with a normal phenotype. European Heart Journal, 22, 410-422. 

Propranolol, nadolol, timolol, penbutolol, carteolol, sotalol, and pindolol Bronchial asthma or bronchospasm, including severe chronic obstructive pulmonary disease. Metoprolol Treatment of Ml in patients with a heart rate less than 45 beats/min significant heart block greater than first degree (PR interval 0.24 seconds or more) systolic blood pressure less than 100 mm Hg moderate to severe cardiac failure. Sotalol Congenital or acquired long QT syndromes. 

Hypersensitivity to the drug or any other component of the product (cross-sensitivity between phenothiazines may occur) comatose or greatly depressed states caused by CNS depressants or from any other cause (phenothiazines, clozapine, loxapine, molindone, pimozide, haloperidol) coadministration with other drugs that prolong the QT interval and in patients with congenital long QT syndrome or history of cardiac arrhythmias (mesoridazine, thioridazine, pimozide, ziprasidone see Drug..Interactions). 

Contraindications Conditions that prolong the QT interval, such as congenital long QT syndrome... 

Electrocardiogram from a patient with the long QT syndrome during two episodes of torsade de pointes. The polymorphic ventricular tachycardia is seen at the start of this tracing and spontaneously halts at the middle of the panel. A single normal sinus beat (NSB) with an extremely prolonged QT interval follows, succeeded immediately by another episode of ventricular tachycardia of the torsade type. The usual symptoms would be dizziness or transient loss of consciousness. 

Adverse effects This drug also had the lowest rate of acute or long-term adverse effects. As with all drugs that prolong the QT interval, the syndrome of torsade de pointes is a serious potential adverse effect, typically seen in 3 to 4% of patients. 

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