Ventricular Tachycardia: Fibrillation and CPR

Ventricular tachycardia occurs when the heart's ventricular chambers contract rapidly: at least 100 times per minute. Most often, damage from a previous heart attack is the cause of ventricular tachycardia. Severe cases of ventricular tachycardia can progress into a condition known as ventricular fibrillation, which can cause sudden cardiac death and requires emergency CPR.

People experiencing ventricular tachycardia may have heart palpitations, feel faint, or find breathing difficult. These symptoms arise as a result of rapid ventricular beats reducing the heart's ability to pump blood to the body. Severe cases of ventricular tachycardia can cause a sudden drop in blood pressure, which may result in fainting.

Diagnosis of ventricular tachycardia is made through EKG interpretation. An EKG device reveals a classic pattern of irregular ventricular contractions if ventricular tachycardia is present.

EKG results for ventricular tachycardia differ markedly from supraventricular tachycardia results. Supraventricular tachycardia results from an electric dysfunction in the atrial chambers, which in turn affects the ventricles. In contrast, ventricular tachycardia results from a direct dysfunction of ventricular electrical signals.

Both supraventricular and ventricular tachycardia can develop into ventricular fibrillation. During ventricular fibrillation the ventricles "quiver" at high speed rather than beat. The ability to pump blood is lost, and sudden cardiac death may occur.

Immediate advanced CPR is required to avoid sudden cardiac death during ventricular fibrillation. Regular CPR is rarely enough to prevent death: Electric shock CPR using defibrillator paddles is required. Time is of the essence. To avoid sudden cardiac death, emergency CPR must be administered as soon as possible.

An ICD may be recommended for people with a high risk of ventricular fibrillation. ICD stands forinternal cardioverter defibrillator. The ICD is surgically attached to the heart, and works in much the same manner as a pacemaker. Ventricular fibrillation triggers the ICD, which releases an electric current. The ICD-produced electric current works as a type of "internal CPR," and hopefully returns the heart rate to normal.

Resources

American Heart Association. (updated 2005). Arrhythmias originating in the ventricles.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S. & Longo, D. (ed). Harrison's Principles of Internal Medicine, 14th Edition. McGraw-Hill, New York, 1998.

Beers, M.H. & Berkow, R. (ed). Ventricular fibrillation. The Merck Manual of Diagnosis and Therapy, 17th Edition. Merck Research Laboratories, NJ, 1999.