February 17, 2012
Dear Mayo Clinic:
I have read with interest your columns on atrial fibrillation. Would you also please comment on conditions of the heart's lower chambers, particularly ventricular tachycardia?
Like atrial fibrillation, ventricular tachycardia involves an abnormal heart rhythm. In people who have ventricular tachycardia, the heart beats faster than normal, due to problems in the heart's two lower chambers, the ventricles. Ventricular tachycardia is a heart disorder that should be evaluated and treated right away. If left untreated, the condition can become serious and possibly life-threatening.
During ventricular tachycardia, both ventricles beat too quickly, often 150 to 280 beats per minute. When this happens, the heart may not be able to pump effectively, making it difficult for the heart to send enough blood to the rest of the body. The result can be symptoms such as decreased blood pressure, light-headedness, weakness and shortness of breath. In some people, ventricular tachycardia can cause blood pressure to drop quickly, and they may faint. In severe cases, the condition may lead to full cardiac arrest and sudden death.
Ventricular tachycardia usually starts in damaged cells within the heart tissue of one ventricle. Often, these cells have been injured by a previous heart problem, such as a heart attack or an infection resulting in fibrosis or scarring. Because of the damage, it is more likely that the normal electrical impulses, which control the rhythm of the heart's pumping action, will be disrupted as they travel through these cells and areas of fibrosis, leading to a fast heartbeat.
Ventricular tachycardia is uncommon in the general population. Less than 1 percent of healthy adults develop the disorder. Factors that can increase a person's risk of ventricular tachycardia include a history of heart disease, a prior heart attack, a heart defect present at birth, or infection of the heart tissue.
Several genetic disorders may also increase the risk of ventricular tachycardia. They include dilated cardiomyopathy, a disorder where the heart muscle is weakened; hypertrophic cardiomyopathy, a disease where the heart muscle becomes abnormally thick; and long QT syndrome, a heart rhythm disorder that can potentially cause fast, chaotic heartbeats.
The first step in treating ventricular tachycardia is to remove from a person's diet anything that could stimulate the damaged heart cells, such as caffeine and alcohol. Smoking can also trigger a fast heartbeat, so smokers with ventricular tachycardia need to quit.
In many cases, removing stimulants and treating the underlying heart disease, if present, can decrease how often ventricular tachycardia occurs, but that may not eliminate the condition completely. Antiarrhythmic medications are often prescribed to help prevent fast heartbeats. If these steps are not enough, or if the condition is severe, a defibrillator may also be used. This device, implanted under the skin and attached to the heart, can sense an abnormal heart rhythm and transmit electrical impulses to help the heart resume a normal rhythm.
When other options don't work, a procedure known as cardiac catheter ablation may be able to prevent ventricular tachycardia. A long, flexible tube, or catheter, is inserted through a vein in the groin and guided through blood vessels to the heart. There, it is placed into the abnormal area where the tachycardia starts. Then, the tip of the catheter is heated and used to destroy the abnormal cells. This prevents the heart's electrical signals from being disrupted and stops the arrhythmia from occurring.
In many cases, ventricular tachycardia can be effectively managed. But this serious heart condition needs prompt attention, preferably from a doctor who specializes in heart rhythm problems. People who have ventricular tachycardia must carefully follow their treatment to keep the disorder under control.
— Stephen Hammill, M.D., Cardiovascular Diseases, Mayo Clinic, Rochester, Minn.