Ventricular tachycardia (V-tach or VT) is a fast rhythm that originates in one of the ventricles of the heart. This is a potentially life-threatening arrhythmia because it may lead to ventricular fibrillation and sudden death. This article or section does not cite its references or sources. ... In the heart, a ventricle is a chamber which collects blood from an atrium (another heart chamber) and pumps it out of the heart. ... The heart and lungs, from an older edition of Grays Anatomy. ... Ventricular fibrillation (V-fib or VF) is a cardiac condition which consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart that eventually leads to the heart stopping altogether. ... A cardiac arrest is the cessation of normal circulation of the blood due to failure of the ventricles of the heart to contract effectively during systole. ...

Classification

12 lead electrocardiogram showing a run of monomorphic ventricular tachycardia (VT)

Ventricular tachycardia can be classified based on its morphology. Monomorphic ventricular tachycardia means that all the beats look generally the same on a surface electrocardiogram (EKG). Polymorphic ventricular tachycardia, on the other hand, has beat-to-beat variations in the morphology of the beats on the EKG. Image File history File links Download high-resolution version (1088x570, 474 KB) 12 lead electrocardiogram of ventricular tachycardia. ... Image File history File links Download high-resolution version (1088x570, 474 KB) 12 lead electrocardiogram of ventricular tachycardia. ... Lead II An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. ... Lead II An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. ...

Another way to classify ventricular tachycardias is the duration of the episodes. Technically, three or more beats in a row on an EKG that originate from the ventricle at a rate of more than 100 beats per minute constitute a ventricular tachycardia. If the fast rhythm self-terminates within 30 seconds, it is considered a non-sustained ventricular tachycardia. If the rhythm lasts more than 30 seconds (even if it terminates on its own after 30 seconds) it is known as a sustained ventricular tachycardia.

Pathophysiology

The cause of ventricular tachycardia depends on the morphology of the tachycardia. In monomorphic ventricular tachycardia, the reason all the beats look the same is because the impulse is being generated from either a single point in either the left or right ventricle or due to a single circuit within the ventricle. The most common cause of monomorphic ventricular tachycardia is a scar of dead tissue from a previous myocardial infarction (heart attack). This scar cannot conduct electrical activity, so there is a potential circuit around the scar that results in the tachycardia. This is similar, at least conceptually, to the re-entrant circuits that are the cause of atrial flutter and the re-entrant forms of supraventricular tachycardia. Acute myocardial infarction (AMI or MI), commonly known as a heart attack, is a disease state that occurs when the blood supply to a part of the heart is interrupted. ... Atrial flutter is a rhythmic, fast rhythm that occurs in the atria of the heart. ... A supraventricular tachycardia (SVT) is a rapid rhythm of the heart in which the origin of the electrical signal is either the atria or the AV node. ...

Polymorphic ventricular tachycardia, on the other hand, is due to electrolyte abnormalities. The most common causes of polymorphic ventricular tachycardia are drug reactions and ischemia of the myocardium (the muscle of the heart). There exist various inherited forms like Long QT syndrome and Catecholaminergic polymorphic ventricular tachycardia. Myocardium is the muscular tissue of the heart. ... The long QT syndrome (LQTS) is a heart disease in which there is an abnormally long delay between the electrical excitation (or depolarization) and relaxation (repolarization) of the ventricles of the heart. ... Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an inherited heart disorder caused by a mutation in voltage gated ion channels and resulting in arrhythmias. ...

Diagnosis

The diagnosis of ventricular tachycardia is made based on the rhythm seen on either a 12 lead EKG or a telemetry rhythm strip. It may be difficult to differentiate between ventricular tachycardia and a wide-complex supraventricular tachycardia in some cases. In particular, supraventricular tachycardias with aberrant conduction (such as ashman beats) are commonly misdiagnosed as ventricular tachycardia. The Ashman phenomenon, also known as Ashman beats, describes a particular type of wide complex tachycardia (fast rhythm of the heart) that is often seen in atrial fibrillation. ...

Various diagnostic criteria have been developed to determine if a wide complex tachycardia is ventricular tachycardia or a more benign rhythm.^[1][2] In addition to these diagnostic criteria, if the individual has a past history of a myocardial infarction, congestive heart failure, or recent angina, the wide complex tachycardia is much more likely to be ventricular tachycardia.^[3] Acute myocardial infarction (AMI or MI), commonly known as a heart attack, is a disease state that occurs when the blood supply to a part of the heart is interrupted. ... Congestive heart failure (CHF), also called congestive cardiac failure (CCF) or just heart failure, is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with or pump a sufficient amount of blood throughout the body. ... The latin word angina refers to a painful constriction or tightness somewhere in the body. ...

The proper diagnosis is important, as the misdiagnosis of supraventricular tachycardia when ventricular tachycardia is present is associated with worse prognosis. This is particularly true if calcium channel blockers, such as verapamil are used to attempt to terminate a presumed supraventricular tachycardia.^[4] Calcium channel blockers are a class of drugs with effects on the muscle of the heart and the muscles of the rest of the body. ... Verapamil (brand names: Isoptin®, Verelan®, Calan®) is a medical drug that acts as an L-type calcium channel blocker. ...

Treatment

There are multiple modalities available to treat ventricular tachycardia. Therapies are generally directed at either terminating an episode of the arrhythmia or for suppressing a future episode from occurring. The treatment is tailored to the specific patient, with regard to how well the individual tolerates episodes of ventricular tachycardia, how frequent episodes occur, and the patient's wishes. The hallmarks of treatment are antiarrhythmic agents and implantable cardioverter-defibrillators (ICDs). In the acute setting, another option is electrical cardioversion using an external defibrillator; however, this is only used if the patient is unconscious and in pulseless ventricular tachycardia. Antiarrhythmic agents are a group of pharmaceuticals that are used to suppress fast rhythms of the heart (cardiac arrhythmias), such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. ... An implantable cardioverter-defibrillator (ICD), also known as an automated implantable cardioverter-defibrillator (AICD), is a device that is implanted under the skin of patients that are at risk of sudden cardiac death due to ventricular fibrillation. ... This article or section does not adequately cite its references or sources. ...

References