Ventricular arrhythmias

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor: Cafer Zorkun, M.D., Ph.D. [2] Vishnu Vardhan Serla M.B.B.S. [3]

Causes of Ventricular Arrhythmias

Cardiac causes

Acute and chronic ischemic heart disease

Cardiomyopathy

Valvular heart disease

Mitral valve prolapse

Noncardiac causes

Stimulants: caffeine, cocaine, alcohol

Metabolic abnormalities: acidosis, hypoxemia, hyperkalemia, hypokalemia, hypomagnesemia

Drugs: Articaine, Cyclophosphamide, digoxin (Lanoxin), theophylline, antipsychotics, tricyclic antidepressants, antiarrhythmics with proarrhythmic potential [e.g., flecainide (Tambocor), dofetilide (Tikosyn), sotalol (Betapace) and quinidine)

An overview of ventricular tachycardias, follow the wide complex tachycardia flowchart

	example	regularity	atrial frequency	ventricular frequency	origin (SVT/VT)	p-wave	effect of adenosine
Wide complex (QRS>0.12)
Ventricular Tachycardia		regular (mostly)	60-100 bpm	110-250 bpm	ventricle (VT)	AV-dissociation	no rate reduction (sometimes accelerates)
Ventricular Fibrillation		irregular	60-100 bpm	400-600 bpm	ventricle (VT)	AV-dissociation	none
Ventricular Flutter		regular	60-100 bpm	150-300 bpm	ventricle (VT)	AV-dissociation	none
Accelerated Idioventricular Rhythm		regular (mostly)	60-100 bpm	50-110 bpm	ventricle (VT)	AV-dissociation	no rate reduction (sometimes accelerates)
Torsade de Pointes		regular		150-300 bpm	ventricle (VT)	AV-dissociation	no rate reduction (sometimes accelerates)
Bundle-branch re-entrant tachycardia*		regular	60-100 bpm	150-300 bpm	ventricles (VT)	AV-dissociation	no rate reduction
(*) Bundle-branch re-entrant tachycardia is extremely rare

Premature Ventricular Complexes (PVCs)

A premature ventricular complex is characterized by the premature occurrence of a QRS complex that is bizarre in shape and lasts longer than 120 msec. The T wave is large and usually of opposite polarity to the QRS complex.

A premature ventricular complex is usually followed by a full compensatory pause. The term “ventricular bigeminy” refers to alternating normal sinus and premature ventricular complexes. Three or more successive premature ventricular complexes are arbitrarily defined as ventricular tachycardia. Premature ventricular complexes become more prevalent with increasing age and occur in association with a variety of stimuli.

It is important to determine whether underlying structural heart disease is present and left ventricular function is impaired.Other common causes include electrolyte abnormalities, stimulants, and some medications.

Management

Patients Without Heart Disease

In the absence of heart disease, PVCs are associated with little or no increased risk of developing a dangerous arrhythmia. In this situation, the risk-to-benefit ratio of antiarrhythmic drug therapy does not support routine treatment. It is important to review medications, determine if stimulants are being used, and correct electrolyte abnormalities. If no underlying cause is found, the optimal approach is patient reassurance. Patients should be made aware of the potential dangers of antiarrhythmic drug therapy as determined in the Cardiac Arrhythmia Suppression Trials (CAST and CAST II).

CAST showed that the risk of dying increased, rather than decreased, with successful long-term suppression of premature ventricular complexes after myocardial infarction in older patients. At best, CAST II showed no impact on long-term survival from drug treatment that successfully suppressed premature ventricular complexes. If patients with multiple premature ventricular complexes have severe, disabling symptoms, beta blockers are the safest initial choice.Referral to a cardiologist is indicated if beta-blocker therapy is not effective. In this situation, the next agents to be tried would be class I antiarrhythmic drugs, such as flecainide (Tambocor) and amiodarone (Cordarone), although radiofrequency ablation of an ectopic focus may also be an appropriate treatment.

Patients with Structural Heart Disease

The occurrence of premature ventricular complexes in patients with structural heart disease has been shown to significantly increase the risk of subsequent morbidity and mortality. Coronary heart disease, cardiomyopathy, and congestive heart failure are the major cardiac diseases associated with unfavorable outcomes in patients with premature ventricular complexes.

Ventricular Tachycardia

Ventricular tachycardia refers to a rhythm originating from a ventricular ectopic focus at a rate >100 bpm. The electrocardiogram shows a wide complex tachycardia with no associated P waves.

In patients with bundle branch block,Wolff-Parkinson-White syndrome, or aberrant conduction, supraventricular tachycardia can resemble ventricular tachycardia. Because of the morbidity and mortality associated with untreated ventricular tachycardia, any wide-complex tachycardia should be assumed to be ventricular tachycardia until proved otherwise. Physicians should keep in mind that patients with ventricular tachycardia can have minimal symptoms.

Management of Ventricular Tachycardia

The mortality rate within two years is reported to be higher than 30% in patients with non sustained ventricular tachycardia on Holter monitoring and impaired left ventricular function. Two large multicenter trials showed a clear advantage for automatic cardioverter defibrillator implantation over drug therapy in patients who had a malignant ventricular arrhythmia or who had been resuscitated from sudden cardiac death. The selection of high-risk patients for defibrillator implantation should be based on left ventricular function and the findings of electrophysiologic studies.

Implantable defibrillators appear to be most beneficial in patients with a low ejection fraction who are noted to have frequent premature ventricular complexes, non sustained ventricular tachycardia on Holter monitoring, and a history of syncope or nearsyncope. It is critical to rule out coronary heart disease and to optimize the treatment of congestive heart failure in these patients. When ventricular tachycardia is diagnosed in relatively asymptomatic patients, medical treatment should be attempted. New recommendations from the American Heart Association emphasize the initial use of 300 mg of iv. administered amiodarone, followed by repeated 150 mg iv. doses every 8-10 minutes, in patients with pulseless VT.

Patients with stable ventricular tachycardia should be given 150 mg of amiodarone intravenously over 10 minutes, followed by an infusion at 1 mg/minute for 6 hours and then at 0.5 mg/minute until the VT converts to sinus rhythm or another less dangerous rhythm. The alternative treatment is intravenously administered lidocaine (Xylocaine), given first in a 100 mg bolus (or 1 mg/kg) and then in an infusion at 1-4 mg/minute.

In hemodynamically unstable patients, electrical cardioversion should be attempted in accordance with the recently revised advanced cardiac life support (ACLS) protocols.

Automatic implantable cardioverter defibrillators (ICD) are considered the most effective treatment for patients with life-threatening VT or VF. According to expert recommendations, implantation of an automatic cardioverter defibrillator should be considered in these situations:

1. Cardiac arrest resulting from ventricular fibrillation or tachycardia not caused by a transient or reversible cause

2. Spontaneous, sustained ventricular tachycardia

3. Syncope of undetermined origin and sustained VT or ventricular fibrillation (VF) induced during electrophysiologic studies

4. Non sustained VT with coronary artery disease and LV dysfunction if VT or VF is induced during electrophysiologic studies.

2006 ACC/AHA/ESC Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death (DO NOT EDIT)

Diagnostic Evaluation

Electrocardiographic Techniques and Measurements (DO NOT EDIT)

Class IIa

"1. It is reasonable to use TWA to improve the diagnosis and risk stratification of patients with ventricular arrhythmias or who are at risk for developing lifethreatening ventricular arrhythmias. (Level of Evidence: A) "

Class IIb

"1. ECG techniques such as signal-averaged ECG (SAECG), heart rate variability (HRV), baroflex sensitivity, and heart rate turbulence may be useful to improve the diagnosis and risk stratification of patients with ventricular arrhythmias or who are at risk of developing life-threatening ventricular arrhythmias. (Level of Evidence: B) "

Resting Electrocardiogram (DO NOT EDIT)

Class I

"1. Resting 12-lead ECG is indicated in all patients who are evaluated for ventricular arrhythmias. (Level of Evidence: A). "

Ambulatory Electrocardiography Recommendations (DO NOT EDIT)

Class I

"1. Ambulatory ECG is indicated when there is a need to clarify the diagnosis by detecting arrhythmias, QT interval changes, T-wave alternans (TWA), or ST changes, to evaluate risk, or to judge therapy. (Level of Evidence: A) "

"2. Event monitors are indicated when symptoms are sporadic to establish whether or not they are caused by transient arrhythmias. (Level of Evidence: B) "

"3. Implantable recorders are useful in patients with sporadic symptoms suspected to be related to arrhythmias such as syncope when a symptom-rhythm correlation cannot be established by conventional diagnostic techniques. (Level of Evidence: B) "

Exercise Testing Recommendations (DO NOT EDIT)

Class I

"1. Exercise testing is recommended in adult patients with ventricular arrhythmias who have an intermediate or greater probability of having CHD by age, gender, and symptoms* to provoke ischemic changes or ventricular arrhythmias. (Level of Evidence: B) *See Table 4 in the ACC/AHA 2002 Guideline Update for Exercise Testing (141) for further explanation of CHD probability."

"2. Exercise testing, regardless of age, is useful in patients with known or suspected exercise-induced ventricular arrhythmias, including catecholaminergic VT, to provoke the arrhythmia, achieve a diagnosis, and determine the patient’s response to tachycardia. (Level of Evidence: B)"

Class III

"1. See Table 1 in the ACC/AHA 2002 Guideline Update for Exercise Testing (141) for contraindications. (Level of Evidence: C)"

Class IIa

"1. Exercise testing can be useful in evaluating response to medical or ablation therapy in patients with known exercise-induced ventricular arrhythmias. (Level of Evidence: B)"

Class IIb

"1. Exercise testing may be useful in patients with ventricular arrhythmias and a low probability of CHD by age, gender, and symptoms.* (Level of Evidence: C) *See Table 4 in the ACC/AHA 2002 Guideline Update for Exercise Testing (141) for further explanation of CHD probability."

"2. Exercise testing may be useful in the investigation of isolated premature ventricular complexes (PVCs) in middle-aged or older patients without other evidence of CHD. (Level of Evidence: C)"

Left Ventricular Function and Imaging (DO NOT EDIT)

Class I

"1. Echocardiography is recommended in patients with ventricular arrhythmias who are suspected of having structural heart disease. (Level of Evidence: B)"

"2. Echocardiography is recommended for the subset of patients at high risk for the development of serious ventricular arrhythmias or SCD, such as those with dilated, hypertrophic, or RV cardiomyopathies, AMI survivors, or relatives of patients with inherited disorders associated with SCD. (Level of Evidence: B)"

"3. Exercise testing with an imaging modality (echocardiography or nuclear perfusion [single-photon emission computed tomography (SPECT)]) is recommended to detect silent ischemia in patients with ventricular arrhythmias who have an intermediate probability of having CHD by age, symptoms, and gender and in whom ECG assessment is less reliable because of digoxin use, LVH, greater than 1-mm ST-segment depression at rest, WPW syndrome, or LBBB. (Level of Evidence: B)"

"4. Pharmacological stress testing with an imaging modality (echocardiography or myocardial perfusion SPECT) is recommended to detect silent ischemia in patients with ventricular arrhythmias who have an intermediate probability of having CHD by age, symptoms, and gender and are physically unable to perform a symptom-limited exercise test. (Level of Evidence: B)"

Class IIa

"1. MRI, cardiac computed tomography (CT), or radionuclide angiography can be useful in patients with ventricular arrhythmias when echocardiography does not provide accurate assessment of LV and RV function and/or evaluation of structural changes. (Level of Evidence: B)"

"2. Coronary angiography can be useful in establishing or excluding the presence of significant obstructive CHD in patients with life-threatening ventricular arrhythmias or in survivors of SCD, who have an intermediate or greater probability of having CHD by age, symptoms, and gender. (Level of Evidence: C)"

"3. LF imaging can be useful in patients undergoing biventricular pacing. (Level of Evidence: C)"

Electrophysiological Testing (DO NOT EDIT)

Class I

"1. EP testing is recommended for diagnostic evaluation of patients with remote MI with symptoms suggestive of ventricular tachyarrhythmias, including palpitations, presyncope, and syncope. (Level of Evidence: B)"

"2. EP testing is recommended in patients with CHD to guide and assess the efficacy of VT ablation. (Level of Evidence: B)"

"3. EP testing is useful in patients with CHD for the diagnostic evaluation of wide QRS complex tachycardias of unclear mechanism. (Level of Evidence: B)"

Class IIa

"1. EP testing is reasonable for risk stratification in patients with remote MI, NSVT, and LVEF equal to or less than 40%. (Level of Evidence: B)"

Management of Special Patient Populations

Management of Ventricular Arrhythmias in Pregnancy (DO NOT EDIT)

Class I

"1. Pregnant women developing hemodynamically unstable VT or VF should be electrically cardioverted or defibrillated. (Level of Evidence: B) (See Section 7.)"

"2. In pregnant women with the LQTS who have had symptoms, it is beneficial to continue beta-blocker medications throughout pregnancy and afterward, unless there are definite contraindications. (Level of Evidence: C)"

Management of Ventricular Arrhythmias in Elderly Patients (DO NOT EDIT)

Class I

"1. Elderly patients with ventricular arrhythmias should generally be treated in the same manner as younger individuals. (Level of Evidence: A)"

"2. The dosing and titration schedule of antiarrhythmic drugs prescribed to elderly patients should be adjusted to the altered pharmacokinetics of such patients. (Level of Evidence: C)"

Class III

"1. Elderly patients with projected life expectancy less than 1 y due to major comorbidities should not receive ICD therapy. (Level of Evidence: C)"

Management of Ventricular Arrhythmias in Pediatric Patients (DO NOT EDIT)

Class I

"1. An ICD should be implanted in pediatric survivors of a cardiac arrest when a thorough search for a correctable cause is negative and the patients are receiving optimal medical therapy and have reasonable expectation of survival with a good functional status for more than 1 y. (Level of Evidence: C)"

"2. Hemodynamic and EP evaluation should be performed in the young patient with symptomatic, sustained VT. (Level of Evidence: C)"

"3. ICD therapy in conjunction with pharmacological therapy is indicated for high-risk pediatric patients with a genetic basis (ion channel defects or cardiomyopathy) for either SCD or sustained ventricular arrhythmias. The decision to implant an ICD in a child must consider the risk of SCD associated with the disease, the potential equivalent benefit of medical therapy, as well as risk of device malfunction, infection, or lead failure and that there is reasonable expectation of survival with a good functional status for more than 1 y. (Level of Evidence: C)"

Class III

"1. Pharmacological treatment of isolated PVCs in pediatric patients is not recommended. (Level of Evidence: C)"

"2. Digoxin or verapamil should not be used for treatment of sustained tachycardia in infants when VT has not been excluded as a potential diagnosis. (Level of Evidence: C)"

"3. Ablation is not indicated in young patients with asymptomatic NSVT and normal ventricular function.(Level of Evidence: C)"

Class IIa

"1. ICD therapy is reasonable for pediatric patients with spontaneous sustained ventricular arrhythmias associated with impaired (LVEF of 35% or less) ventricular function who are receiving chronic optimal medical therapy and who have reasonable expectation of survival with a good functional status for more than 1 y. (Level of Evidence: B)"

"2. Ablation can be useful in pediatric patients with symptomatic outflow tract or septal VT that is drug resistant, when the patient is drug intolerant or wishes not to take drugs. (Level of Evidence: C)"

Resources

1. Zipes DP, Camm AJ, Borggrefe M, et al., ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death)Circulation 2006;114;e385-e484

2. Kesh Hebbar A, Hueston WJ, Management of Common Arrhythmias: Part II.Ventricular Arrhythmias and Arrhythmias in Special Populations Am Fam Physician 2002;65:2491-6.