Ventricular tachycardia treatment


 * Associate Editor-in Chief: Avirup Guha, M.B.B.S.[mailto:avirup.guha@gmail.com]

Treatment of ventricular tachycardia
Therapy may be directed at either terminating an episode of the arrhythmia or for suppressing a future episode from occurring. The treatment is tailored to the specific patient, with regard to how well the individual tolerates episodes of ventricular tachycardia, how frequently episodes occur, their comorbidities, and their wishes.

The details of the guidelines for treatment are explained better in the guidelines section later in this article

Electrical Cardioversion / Defibrillation
It is usually possible to terminate a VT episode with a direct current shock across the heart. This is ideally synchronised to the patient's heartbeat. As it is quite uncomfortable, shocks should be delivered only to an unconscious or sedated patient. A patient with pulseless VT will be unconscious and treated as an emergency on a cardiac arrest protocol. Elective cardioversion is usually performed in controlled circumstances with anaesthetic and airway support.

The shock may be delivered to the outside of the chest using an external defibrillator, or internally to the heart by an implantable cardioverter-defibrillator (ICD) if one has previously been inserted.

An ICD may also be set to attempt to overdrive pace the ventricle. Pacing the ventricle at a rate faster than the underlying tachycardia can sometimes be effective in terminating the rhythm. If this fails after a short trial, the ICD will usually stop pacing, charge up and deliver a defibrillation grade shock.

Antiarrhythmic drug therapy
Drugs such as amiodarone, epinephrine and vasopressin may be used in addition to defibrillation to terminate VT while the underlying cause of the VT can be determined. Possible causes or contributing factors to VT can be remembered as the six H's and five T's: Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo- or Hyperglycemia, Hypothermia; and Toxins, Tamponade (cardiac), Tension pneumothorax, Thrombosis, Trauma.

Long term anti-arrhythmic therapy may be indicated to prevent recurrence of VT. Beta-blockers and a number of class III anti-arrhythmics are commonly used.

For some of the rare congenital syndromes of VT, other drugs, and sometimes even catheter ablation therapy may be useful.

The implantation of an ICD is more effective than drug therapy for prevention of sudden cardiac death due to VT and VF, but may be constrained by cost issues, and well as patient co-morbidities and patient preference.

==Guidelines in Ventricular Tachycardia Treatment ==

Recommendations in Ablation of Ventricular Tachycardia
{{cquote|

Class I
1. Ablation is indicated in patients who are otherwise at low risk for Sudden Cardiac Death(SCD) and have sustained predominantly monomorphic ventricular tachycardia that is drug resistant, who are drug intolerant, or who do not wish long-term drug therapy.(Level of Evidence: C)

2. Ablation is indicated in patients with Bundle branch reentrant ventricular tachycardia.(Level of Evidence: C)

3. Ablation is indicated as adjunctive therapy in patients with an Implantable cardioverter-defibrillator(ICD) who are receiving multiple shocks as a result of Sustained VT that is not manageable by reprogramming or changing drug therapy or who do not wish long-term drug therapy. (Level of Evidence: C)

4. Ablation is indicated in patients with WPW syndrome resuscitated from sudden cardiac arrest due to AF and rapid conduction over the accessory pathway causing VF. (Level of Evidence: B))

Class IIa
1. Ablation can be useful therapy in patients who are otherwise at low risk for SCD and have symptomatic nonsustained monomorphic VT that is drug resistant, who are drug intolerant or who do not wish long-term drug therapy.(Level of Evidence: C)

2. Ablation can be useful therapy in patients who are otherwise at low risk for SCD and have frequent symptomatic predominantly monomorphic PVCs that are drug resistant or who are drug intolerant or who do not wish long-term drug therapy.(Level of Evidence: C)

3. Ablation can be useful in symptomatic patients with WPW syndrome who have accessory pathways with refractory periods less than 240 ms in duration. (Level of Evidence: B)

Class IIb
1. Ablation of Purkinje fiber potentials may be considered in patients with ventricular arrhythmia storm consistently provoked by PVCs of similar morphology. (Level of Evidence: C)

2. Ablation of asymptomatic PVCs may be considered when the PVCs are very frequent to avoid or treat tachycardia-induced cardiomyopathy. (Level of Evidence: C)

Class III
Ablation of asymptomatic relatively infrequent PVCs is not indicated. (Level of Evidence: C)}}

Recommendations for Acute Management Of Ventricular Tachycardia(and other arrhythmias)
{{cquote| ===2005 Guidelines ===

Class I
1. After establishing the presence of definite, suspected, or impending cardiac arrest, the first priority should be activation of a response team capable of identifying the specific mechanism and carrying out prompt intervention. (Level of Evidence: B)

2. Cardiopulmonary resuscitation (CPR) should be implemented immediately after contacting a response team. (Level of Evidence: A)

3. In an out-of-hospital setting, if an AED is available, it should be applied immediately and shock therapy administered according to the algorithms contained in the documents on CPR developed by the AHA in association with the International Liaison Committee on Resuscitation (ILCOR) and/or the European Resuscitation Council (ERC). (Level of Evidence: C)

4. For victims with ventricular tachyarrhythmic mechanisms of cardiac arrest, when recurrences occur after a maximally defibrillating shock (generally 360 J for monophasic defibrillators), intravenous amiodarone should be the preferred antiarrhythmic drug for attempting a stable rhythm after further defibrillations. (Level of Evidence: B)

5. For recurrent ventricular tachyarrhythmias or nontachyarrhythmic mechanisms of cardiac arrest, it is recommended to follow the algorithms contained in the documents on CPR developed by the AHA in association with ILCOR and/or the ERC. (Level of Evidence: C)

6. Reversible causes and factors contributing to cardiac arrest should be managed during advanced life support, including management of hypoxia, electrolyte disturbances, mechanical factors, and volume depletion. (Level of Evidence: C)

Class IIa
For response times greater than or equal to 5 min, a brief (less than 90 to 180 s) period of CPR is reasonable prior to attempting defibrillation. (Level of Evidence: B)

Class IIb
A single precordial thump may be considered by health care professional providers when responding to a witnessed cardiac arrest. (Level of Evidence: C)

===2010 Guidelines(from the section on cardioversion and wide complex tachycardia only - incomplete and will be made better once the new guidelines after 2006 are released) ===

Class IIa
1.Cardioversion with monophasic waveforms should begin at 200 J and increase in stepwise fashion if not successful. (Level of Evidence: B)

2.If the etiology of the rhythm cannot be determined, the rate is regular, and the QRS is monomorphic, recent evidence suggests that IV adenosine is relatively safe for both treatment and diagnosis. (Level of Evidence: B)

3.If IV antiarrhythmics are administered, procainamide can be considered. (Level of Evidence: B)

4.If antiarrhythmic therapy is unsuccessful, cardioversion or expert consultation should be considered. (Level of Evidence: C)

Class IIb
1.Monomorphic VT with a pulse responds well to monophasic or biphasic waveform cardioversion(synchronized) shocks at initial energies of 100 J. If there is no response to the first shock, it may be reasonable to increase the dose in a stepwise fashion. (Level of Evidence: C)

2.Precordial thump may be considered for patients with witnessed, monitored, unstable ventricular tachycardia if a defibrillator is not immediately ready for use. (Level of Evidence: C)

3.If IV antiarrhythmics are administered, amiodarone or sotalol can be considered. (Level of Evidence: B)

Class III
1.Adenosine should not be given for unstable or for irregular or polymorphic ventricular tachycardias, as it may cause degeneration of the arrhythmia to VF. (Level of Evidence: C)

2.Verapamil is contraindicated for wide-complex tachycardias unless known to be of supraventricular origin. (Level of Evidence: B)

3.If one of these antiarrhythmic agents is given, a second agent should not be given without expert consultation. (Level of Evidence: B)}}

Recommendation for Specific Kinds of Ventricular Arrhythmias
Category : Electrophysiology