Torsade de pointes

Prepared By:

Objective

• Introduction

• Mechanism

• Causes of torsade de pointes

• Symptoms

• Treatment

introduction

• Torsades de pointes (TdP) is a specific form of polymorphic ventricular tachycardia , it has a characteristic morphology in which the QRS complexes “twist” around the isoelectric line.

• Torsades de pointes is associated with long QT syndrome, a condition whereby prolonged QT intervals are visible on the ECG

Normal ECG

QT interval prolongation

QT prolongation leading to Tdp

The steps of repolarization

The effect of QT prolongation

• when the period of repolarization is extended, the myocardial cells become less refractory to electrical stimuli and more likely to depolarize prematurely.

• leads to subsequent depolarizing currents and sometimes action potentials, termed afterdepolarizations. This leads to a further delay in repolarization and causes early afterdepolarization (EAD), the triggering event for torsade.

Ionic imbalance

causes

• Acquired• patients acquire LQTS from the medication they're taking.

• Congenital • individuals with genetic mutations in genes that cause

prolongation of QT interval .

Cause of Torsade de pointes

• Electrolyte abnormalities - Hypokalemia, hypomagnesemia, hypocalcemia

• -Endocrine disorders - Hypothyroidism, hyperparathyroidism, pheochromocytoma, hyperaldosteronism

• -Cardiac conditions - Myocardial ischemia, myocardial infarction, myocarditis, bradyarrhythmia, complete atrioventricular (AV) block, takotsubo cardiomyopathy

Causes of Torsade de pointes

• Intracranial disorders - Subarachnoid hemorrhage, thalamic hematoma, cerebrovascular accident, encephalitis, head injury

• -Nutritional disorders - Anorexia nervosa, starvation, liquid protein diets, gastroplasty and ileojejunal bypass, celiac disease.

Symptoms • Patients with torsades usually present with

recurrent episodes of palpitations, dizziness, and syncope. Sudden cardiac death can occur with the first episode.

• Nausea, cold sweats, shortness of breath and chest pain may occur.

Treatment

• Defibrillation• Discontinuation of any QT prolonging drugs• Magnesium is the drug of choice for suppressing EADs and

terminating the arrhythmia. Magnesium achieves this by decreasing the influx of calcium, thus lowering the amplitude of EADs.

• Isoproterenol can be used in bradycardia-dependent torsade that usually is associated with acquired long QT syndrome

• Beta-adrenergic antagonists are used as a first-line long-term therapy in congenital long QT syndrome.

Overview

• Torsade de pointes is form of polymorphic ventricular tachycardia (VT) .

• Tdp is associated with a prolonged QT interval.• Torsade usually terminates spontaneously but

frequently recurs and may degenerate into ventricular fibrillation or sudden death.

• In torsade, the morphology of the QRS complexes varies from beat to beat

• It can be treated by pacing or anti-QT prolonging drugs

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