Ventricular Tachycardia

Ventricular tachycardia, or V-tach, is an abnormally fast heart rhythm that originates in the heart's lower chambers, the ventricles. Brief episodes may cause no lasting harm, but a sustained episode is dangerous and can turn into ventricular fibrillation and cardiac arrest, appearing in about 7 percent of cardiac arrest cases. Short episodes may cause no symptoms or produce lightheadedness, palpitations, chest pain, and shortness of breath, while more severe or prolonged episodes can cause unconsciousness or coma from inadequate blood flow to the brain. It can be triggered by coronary heart disease, heart valve problems, cardiomyopathy, electrolyte imbalances, a prior heart attack, inherited electrical disorders of the heart called channelopathies, or alcohol withdrawal, and is diagnosed on an electrocardiogram by a heart rate over 120 beats per minute with a characteristic electrical pattern.