| Ventricular tachycardia is an abnormal heart rhythm (arrhythmia) in which the heartbeat is initiated in the lower heart chambers (ventricles) rather than from the sinoatrial (SA) node in the right upper heart chamber (right atrium). As a result, the heart beats at an abnormally fast rate of 140 to 220 beats per minute.
Ventricular tachycardia may last as long as several days (sustained) or as little as 30 seconds or less (nonsustained).
Ventricular tachycardia occurs most often in individuals with pre-existing heart disease, such as diseases of the heart valves (e.g., valve prolapse), congenital heart disease, insufficient oxygen to the heart muscle (ischemic heart disease), disease of the heart muscle (cardiomyopathy), coronary artery disease, or rheumatic heart disease. Nonsustained ventricular tachycardia may occur in individuals with no underlying cardiac disease. Ventricular tachycardia can also occur after a heart attack (acute myocardial infarction), or as a result of drug toxicity. A form of ventricular tachycardia associated with drug toxicity (Torsade de Pointes) has an abrupt onset and a poor prognosis.Risk: Risk factors include increasing age and male sex due to increased frequency of coronary artery disease in men. Incidence and Prevalence: The incidence of ventricular tachycardia is difficult to determine because of the lack of symptoms when it is nonsustained. Sustained ventricular tachycardia occurs in about 3% of individuals who have experienced a myocardial infarction (Volpi). It is estimated that ventricular tachycardia or ventricular arrhythmia accounts for most of the 300,000 sudden cardiac deaths (SCD) per year in the US (Saliba). |
Source: Medical Disability Advisor
| History: The individual may report no symptoms at all (asymptomatic). However, most individuals complain of light-headedness, weakness, chest discomfort or pain, shortness of breath (dyspnea), sensation of the heart beating rapidly or intensely (palpitations), abrupt loss of consciousness (syncope), and/or seizures. Physical exam: The exam may reveal a pulse that is weak, rapid, or cannot be felt (nonpalpable). There may be inconsistencies in the blood pressure or abnormal (muffled) heart sounds. The individual may appear anxious, agitated, or may lose consciousness. There may be signs of heart failure such as crackles on listening to the lungs with a stethoscope (auscultation), dyspnea, and low blood oxygen levels (hypoxemia). Tests: Diagnosis is confirmed by recording the electrical activity of the heart (electrocardiogram, or ECG). This record of the electrical activity will show broad and abnormal waves (QT interval prolongation), a heart rate greater than 100, and presence of the atria and ventricles beating separately (AV dissociation). An intracardiac electrophysiology study (EPS) may be ordered to confirm the arrhythmia and define the area causing the arrhythmia.
Blood tests may be administered to determine other causes, including abnormal levels for drugs, thyroid hormones, and potassium (serum electrolytes)—as well as calcium or evidence of an underlying myocardial infarction.
If valvular heart disease or cardiomyopathy is suspected, an ultrasound of the heart (echocardiography) or cardiac catherization may be required. |
Source: Medical Disability Advisor
| Individuals who have nonsustained ventricular tachycardia but have no structural damage to the heart muscle, valves, or other symptoms may not require drug treatment. Underlying metabolic abnormalities or other cardiac disorders that may cause the condition should be treated. Toxic drug intake should be discontinued if it is causing ventricular tachycardia.
Sustained ventricular tachycardia is a medical emergency requiring immediate intervention to preserve life. Sustained ventricular tachycardia is treated initially with anti-arrhythmic drugs. Administration of an electric shock to the heart (electric cardioversion) may be required if a normal heartbeat (rhythm) is not restored quickly with drugs. Striking the individual's chest (thump conversion) may be used if the onset is observed. After normal heart rhythm is restored, an anti-arrhythmic drug is usually continued for several months. Treatment of individuals with chronic, recurrent ventricular tachycardia is controversial. A device that shocks the heart into its normal rhythm may be implanted surgically (implantable cardiac defibrillator, ICD) followed by administration of anti-arrhythmic drugs if the arrhythmia continues despite the ICD. Individuals with continued recurrence notwithstanding these methods of treatment may require a procedure to burn the area causing the arrhythmia (radiofrequency catheter ablation, catheter ablation).
Sustained ventricular tachycardia can deteriorate into loss of contractile ability by the heart (ventricular fibrillation). This is a medical emergency in which death is a possibility. |
Source: Medical Disability Advisor
| The predicted outcome for individuals who experience nonsustained ventricular tachycardia depends upon the underlying cause for the condition. The outcome is good for individuals who experience ventricular tachycardia as a one time experience. Complete recovery without lasting adverse reactions may be expected if there is no serious underlying heart disease.
Torsade de Pointes is usually related to drug toxicity and can lead to sudden death. Torsade de Pointes will lead to cardiac arrest in 50% of cases.
After a myocardial infarction, the risk of death is 5% to 10%; for those with a prior myocardial infarction and nonsustained ventricular tachycardia, the 2-year mortality rate is 30%; and for those with ventricular tachycardia that can be caused by EPS study (inducible), the 2-year mortality is 50% (Braunwald).
There is approximately a 30% overall reduction in mortality in individuals with sustained ventricular tachycardia who have an implanted cardiac defibrillator. However, individuals who have a cardiac defibrillator implanted surgically will experience SCD in 1% to 2% of cases annually. |
Source: Medical Disability Advisor
| Possible complications of ventricular tachycardia include progression to a complete lack of organized ventricular contractions (ventricular fibrillation), low blood pressure (hypotension), general organ and cardiovascular system failure (shock), an abnormal condition of the heart characterized by circulatory congestion (congestive heart failure), and death.
Additional complications include reaction to medications used to treat the arrhythmia or surgical complications if an implantable cardioverter defibrillator is implanted. These include infection and malfunction of the device. |
Source: Medical Disability Advisor
| A leave of absence for treatment may be required. Individuals who continue to experience sudden fainting spells (syncope) or dizziness may need limitations on access to unrestricted heights, dangerous machinery, driving, or hazardous work. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Does individual complain of light-headedness, weakness, chest discomfort, shortness of breath (dyspnea), sensation of the heart beating rapidly or intensely (palpitations), abrupt loss of consciousness (syncope), and/or seizures?
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Does individual have a history of heart disease or a recent heart attack?
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Are there other underlying conditions that would contribute to ventricular tachycardia?
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Does physician note a pulse that is weak, rapid, or cannot be felt (nonpalpable)?
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Are there inconsistencies in the blood pressure or abnormal (muffled) heart sounds?
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Does individual appear anxious or agitated?
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Was a recording of the electrical activity of the heart (electrocardiogram, or ECG) obtained?
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Was an intracardiac electrophysiology study (EPS) done?
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Has the diagnosis been confirmed?
Regarding treatment:
- Has ventricular tachycardia become more frequent?
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Does individual require drug treatment?
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Have underlying medical conditions been treated?
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Are the appropriate anti-arrhythmic drugs being prescribed?
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Is individual taking these exactly as prescribed?
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Would implantation of a cardiac defibrillator be of benefit?
Regarding prognosis:
- Did individual experience nonsustained ventricular tachycardia?
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Did individual recover completely with or without treatment?
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Has individual developed Torsade de Pointes? What can be done for this condition?
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Are anti-arrhythmic drugs treating the tachycardia successfully?
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Is individual compliant with the medication regimen?
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Has the condition recurred?
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Does individual have a defibrillator implanted? If so, is it functioning properly?
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Has individual developed any complications? If so, what are they?
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Is individual expected to survive these complications?
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Source: Medical Disability Advisor
| Braunwald, E., et al., eds. "Specific Arrhythmias: Diagnosis and Treatment." Heart Disease: A Textbook of Cardiovascular Medicine. 6th ed. Philadelphia: W.B. Saunders, 2001. 857-863. MD Consult. Elsevier, Inc. 31 May 2004 <http://home.mdconsult.com/das/book/37963480-4/view/924?sid=273675998>.Saliba, Walid, and Andrea Natale. "Ventricular Tachycardia Syndromes." Medical Clinics of North America 85 2 (2001): 267-304. MD Consult. Elsevier, Inc. 31 May 2004 <http://home.mdconsult.com>. Volpi, Alberto. "Incidence and Short-term Prognosis of Late Sustained Ventricular Tachycardia after Myocardial Infarction: Results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto." American Heart Journal 142 1 (2001): 87-92. MD Consult. Elsevier, Inc. 6 Nov. 2004 <http://home.mdconsult.com/das/journal/view/42258002-2/N/11897751?sid=273675997&source=MI>. |
Source: Medical Disability Advisor
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