Tachycardia: Difference between revisions
→Ventricular tachycardia
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=Ventricular tachycardia= | =Ventricular tachycardia= | ||
Ventricular tachycardias are rhythm disturbances that arise in the ventricles. | |||
==Ventricular tachycardia== | ==Ventricular tachycardia== | ||
Ventricular tachycardia (VT) is defined as a sequence of three or more ventricular beats. The frequency is often 110-250 bpm. Ventricular tachycardias often origin around old scar tissue in the heart, e.g. after myocardial infarction. Also electrolyte disturbances and ischemia can cause ventricular tachycardias. The cardiac output is often strongly reduced during VT resulting in hypotension and loss of conciousness. VT is a medical emergency as it can deteriorate into ventricular fibrillation and thus mechanical cardiac arrest. | |||
===Definitions:=== | |||
*'''Non-sustained VT''': three or more ventricular beats with a maximal duration of 30 seconds. | |||
*'''Sustained VT''': a VT of more than 30 seconds duration (or less if treated by electrocardioversion within 30 seconds). | |||
*'''Monomorphic VT''': all ventricular beats have the same configuration. | |||
*'''Polymorphic VT''': the ventricular beats have a changing configuration. The heart rate is 100-333 bpm. | |||
*'''Biphasic VT''': a ventricular tachycardia with a QRS complex that alternates from beat to beat. Associated with [[Miscellaneous#Digoxin|digoxin intoxication]] and [[lqts|long QT syndrome]]. | |||
===Localisation of the origin of a ventricular tachycardia:=== | |||
Determination of the location (or exit site) where a ventricular tachycardia originated, can be helpful in understanding the cause of the VT and is very helpful when planning an ablation procedure to treat a ventricular tachycardia. (new page for localization) | |||
===Differential diagnosis=== | |||
(Non)sustained monomorphic VT may be idiopathic, but occurs most frequently in patients with underlying structural heart disease of various types including: | |||
* Coronary heart disease (CHD) with prior myocardial infarction (is the most frequent cause in developed countries) | |||
* Hypertrophic cardiomyopathy | |||
* Dilated cardiomyopathy | |||
* Mitral valve prolapse | |||
* Aortic stenosis | |||
* Complex congenital heart disease | |||
* Cardiac sarcoidosis | |||
* Arrhythmogenic RV cardiomyopathy/dysplasia | |||
==Ventricular flutter== | ==Ventricular flutter== | ||
==Ventricular fibrillation== | ==Ventricular fibrillation== | ||
VF is lethal if the patient is not treated immediately. It gives rise to a mechanical standstill of the heart, because the heart is not able to pump normally anymore. | |||
==Torsade de Pointes== | ==Torsade de Pointes== | ||