Ventricular tachycardia: Difference between revisions

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[[Image:Torsades_de_Pointes.png|thumb|400px|Torsade de Pointes, preceded by bigemini.]]
[[Image:Torsades_de_Pointes.png|thumb|400px|Torsade de Pointes, preceded by bigemini.]]


Torsades de pointes (TdP) is a ventricular tachycardia associated with a prolonged QTc interval on the resting ECG. The ECG during TdP is characterized by twisting of the peaks of the QRS complexes around the isoelectric line during the arrhythmia (changing axis). Torsade de pointes is typically initiated by a short-long-short interval. A ventricle extrasystole (first beat: short) is followed by a compensatory pause. The following beat (second beat: long) has a longer QT interval. If the next beat follows shortly thereafter (third beat: short), there is a good chance that this third beat falls within the QT interval, resulting in the R on T phenomenon and subsequent Torsades de pointes.  
Torsades de pointes (TdP) is a ventricular tachycardia associated with a prolonged QTc interval on the resting ECG. It is on the ECG characterized by twisting of the peaks of the QRS complexes around the isoelectric line during the arrhythmia (changing axis). Torsade de pointes is typically initiated by a short-long-short interval. A ventricle extrasystole (first beat: short) is followed by a compensatory pause. The following beat (second beat: long) has a longer QT interval. If the next beat follows shortly thereafter, there is a good chance that this third beat falls within the QT interval, resulting in the R on T phenomenon and subsequent Torsades de pointes.  


See the chapter on [[LQTS]] for a list of medication and genes that can cause QT prolongation and TdP.
===Differential diagnosis===
*Aquired long QT syndrome (complete list of drugs causing long QT syndrome: [http://www.torsades.org http://www.torsades.org])
*Congenital long QT syndrome


===Treatment===
===Treatment===
Electrocardioversion is the first treatment for an unconcious patient with incessant TdP.  
Electrocardioversion is the first treatment for TdP.  


'''Additional treatments are:'''
Additional treatments are:  
*Withdrawal of any offending drugs and correction of electrolyte abnormalities (potassium repletion up to 4.5 to 5 mmol/liter, the goal should be to make the patient slightly hyperkalemic).  
*Withdrawal of any offending drugs and correction of electrolyte abnormalities (potassium repletion up to 4.5 to 5 mmol/liter).  
*Acute and long-term cardiac pacing in patients with TdP presenting with heart block, symptomatic bradycardia or recurrent pause-dependent TdP  
*Acute and long-term cardiac pacing in patients with TdP presenting with heart block, symptomatic bradycardia or recurrent pause-dependent TdP  
*Intravenous magnesium sulfate can be helpful to cardiovert TdP in the acute phase in patients with few TdP episodes. If recurrence occurs a continues infusion may be beneficial.
*Intravenous magnesium sulfate for patients with QT prolongation and few episodes of TdP.  
*Beta blockers combined with cardiac pacing as acute therapy for patients with TdP and sinus bradycardia. This prevents extrasystoles and thereby short-long-short sequences.
*Beta blockers combined with cardiac pacing as acute therapy for patients with TdP and sinus bradycardia.  
*Isoproterenol as temporary treatment in patients with recurrent pause-dependent TdP who do not have congenital long QT syndrome.  
*Isoproterenol as temporary treatment in patients with recurrent pause-dependent TdP who do not have congenital long QT syndrome.


==Differentiation between SVT and VT==
==Differentiation between SVT and VT==

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