Ventricular Tachycardia

In the condition of ventricular tachycardia, the heartbeat is increased causing a sudden drop in the blood pressure, resulting in inability of the heart to pump blood to other body organs. Such sequence of events gives rises to the following symptoms:

• Development of discomfort in the chest followed by angina pain
• Fainting
• Dyspnea
• Palpitations
• Feeling of dizziness or light headedness
• In many cases, it may so happen that individuals may not experience any signs and symptoms [7].

• The preliminary diagnosis is done using electrocardiogram that measures the electrical activity of the heart. In case when the patient is hemodynamically stable then, 12-lead ECG and electrolyte levels are first obtained. ECG would also provide appropriate information regarding the cause, which leads to development of ventricular tachycardia. This would also help differentiate between potential arrhythmias [8]. 
• Following this, appropriate laboratory studies along with echocardiography and coronary angiography are indicated. These are required for designing a suitable treatment regime.
• Chest radiography is conducted in conditions, when presenting symptoms suggest heart failure or any other cardiopulmonary pathology as the causative factor. Imaging studies such as CT scan and MRI do not provide useful information for diagnosing ventricular tachycardia.

• The major goal of treatment of ventricular tachycardia is to manage any underlying disease condition. In emergency situations, patients are given cardiopulmonary resuscitation to stabilize the abnormal heart beats.
• Long term management of the condition includes administration of anti-arrhythmic medications. These however, have several side effects and should therefore be used with caution. In addition to medications, individuals are also given implantable cardioventer-defibrillator and catheter ablation [9]. Cardiac ablation is indicated in patients with recurrent ventricular tachycardia. This method is safer when compared to anti-arrhythmic medications and can also be safely used in patients with advanced heart diseases [10].
• Cardioverter–defibrillator is a type of device that is implanted under the skin, for constant monitoring and controlling heart’s rhythm. It is one of the most effective treatment regimens to avoid development of life threatening complications of ventricular tachycardia.
• In many cases, combination of treatment methods for managing the condition of patients with structural heart diseases is required.

Prognosis of ventricular tachycardia depends on the functioning of left ventricles. The underlying disease conditions and severity of the symptoms also affect the prognosis. However, left ventricular functioning may not always be the determining factor for prognosis of ventricular tachycardia. Studies have shown that individuals with good left ventricular functioning, but having long QT syndrome, and hypertrophic cardiomyopathy are at an increased risk of sudden death. It has been estimated that, about 30% individuals with non-sustained ventricular tachycardia and ischemic cardiomyopathy are more likely to suffer sudden death within 2 years of onset of disease. Prognosis is excellent in individuals with idiopathic ventricular tachycardia [6].

Heart diseases are the most common cause of ventricular tachycardia. Individuals with cardiomyopathy, myocarditis, heart failure, or valvular heart disease are at an increased risk of developing this condition. Ventricular tachycardia often is a common accompaniment in patients, who have undergone heart surgery.

In addition to underlying heart disorders the following factors can predispose an individual to develop ventricular tachycardia:

• Electrolyte imbalances, characterized by changes in the levels of potassium, magnesium and calcium
• Medications 
• Lack of oxygen
• Ph changes
• Development of systemic diseases such as systemic lupus erythematosus, rheumatoid arthritis, amyloidoisis, hemochromatosis and sarcoidosis
• Inherited channelopathies, which include long and short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome [2]

The incidence rate of ventricular tachycardia is higher in the developed nations. In developing countries, the prevalence of these diseases is relatively low. It has been estimated that, in the US, ventricular tachycardia was the major cause of sudden death in about 300,000 cases each year [3].

Statistics have revealed that ventricular tachycardia accounts for 5.6% of all mortality. Men are more prone to develop the disease condition, mainly because of higher incidence of ischemic heart diseases in them. Females, who have long QT syndrome, are more prone to develop ventricular tachycardia [4].

Under normal physiological conditions, the heart rate is effectively controlled by the electrical signals, which are transmitted across the heart muscles. Various conditions may cause the signals to be sent too rapidly, leading to development of ventricular tachycardia. Rapid heartbeats in turn lead to decreased cardiac output which results from decreased ventricular filling. In conditions of ischemic heart disease and mitral valve insufficiency, there is also significant decrease in ventricular stroke output as well as reduced hemodynamic tolerance [5].

Majority of the cases of ventricular tachycardia cannot be prevented. However, individuals with underlying heart diseases should get it treated in order to prevent the onset of ventricular tachycardia.

Ventricular tachycardia (VT) is a dangerous form of arrhythmia, which can call for development of debilitating complications. Individuals affected by ventricular tachycardia, have heart rate of more than 100 beats/minute, accompanied by 3 or more irregular beats. Underlying disease condition, heart diseases, myocardial infarction and heart surgery, all can cause ventricular tachycardia to develop [1].

• Definition: Ventricular tachycardia is a condition, characterized by rapid heartbeats, which initiates from the ventricles. In this disorder, the pulse rate of the affected individuals goes beyond 100 beats/minute. 
• Cause: Patients with underlying disease conditions are at an increased risk of contracting ventricular tachycardia. Conditions such as cardiomyopathy, myocarditis, heart failure and valvular heart disease favor development of ventricular tachycardia. The condition can also occur as a complication in patients who have undergone heart surgery.
• Symptoms: Symptoms of tachycardia include discomfort in chest, light headedness, dizziness and palpitations. In many cases, individuals also experience shortness of breath and can even faint. 
• Diagnosis: Conducting electrocardiogram forms the basis of diagnosis procedure. This is done to measure the electrical activity of the heart. In addition to this, certain other tests such as chest radiography and coronary angiography would also be required.
• Treatment: In emergency situations, stabilizing the heart rate and bringing it to a normal state is the primary goal of treatment. Medications, catheter ablation and cardioverter defibrillation are also indicated depending on condition of the patient.

1. Turker Y, Ozaydin M, Acar G, Ozgul M, Hoscan Y, Varol E, et al. Predictors of ventricular arrhythmias in patients with mitral valve prolapse. Int J Cardiovasc Imaging. Feb 2010;26(2):139-45.
2. Brugada J, Brugada R, Brugada P. Channelopathies: a new category of diseases causing sudden death.Herz. May 2007;32(3):185-91
3. McNally B, Robb R, Mehta M, Vellano K, Valderrama AL, Yoon PW, et al. Out-of-hospital cardiac arrest surveillance --- Cardiac Arrest Registry to Enhance Survival (CARES), United States, October 1, 2005--December 31, 2010. MMWR Surveill Summ. Jul 29 2011;60(8):1-19
4. Buxton AE. Patients with nonsustained ventricular tachycardia. In: Sudden Cardiac Death: Prevalence, Mechanisms, and Approach to Diagnosis and Management, Akhtar M, Myerburg R, Ruskin J (Eds), Williams & Wilkins, Baltimore 1994.
5. Sarter BH, Finkle JK, Gerszten RE, Buxton AE. What is the risk of sudden cardiac death in patients presenting with hemodynamically stable sustained ventricular tachycardia after myocardial infarction? J Am Coll Cardiol 1996; 28:122.
6. Turakhia M, Tseng ZH. Sudden cardiac death: epidemiology, mechanisms, and therapy. Curr Probl Cardiol. Sep 2007;32(9):501-46.
7. Monserrat L, Elliott PM, Gimeno JR, et al. Non-sustained ventricular tachycardia in hypertrophic cardiomyopathy: an independent marker of sudden death risk in young patients. J Am Coll Cardiol 2003; 42:873.
8. Josephson ME, Callans DJ. Using the twelve-lead electrocardiogram to localize the site of origin of ventricular tachycardia. Heart Rhythm. Apr 2005;2(4):443-6.
9. Wellens HJ, Bär FW, Lie KI. The value of the electrocardiogram in the differential diagnosis of a tachycardia with a widened QRS complex. Am J Med. Jan 1978;64(1):27-33
10. Sarkozy A, Tokuda M, Tedrow UB, et al. Epicardial ablation of ventricular tachycardia in ischemic heart disease. Circ Arrhythm Electrophysiol 2013; 6:1115.