All You Need To Know About Nonsustained Ventricular Tachycardia

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Illustration of a heart in a monitor as a metaphor for Nonsustained ventricular tachycardia

Introduction

Nonsustained ventricular tachycardia (NSVT) is characterized by 3 or more consecutive beats originating below the atrioventricular node with an RR interval of fewer than 100 beats per minute and lasts for less than 30 seconds. It is a common form of arrhythmia.
It is normally asymptomatic and is most often diagnosed during an exercise test or cardiac monitoring.

NSVT presence is a potential sign for the development of sustained ventricular arrhythmia and sudden death. NSVT has been observed in different conditions, from healthy individuals to individuals with a significant heart condition.

Symptoms of NSVT

Nonsustained Ventricular Tachycardia is often asymptomatic and does not produce alarming symptoms but is usually discovered incidentally through ECG or other forms of cardiac monitoring. Some individuals experience symptoms such as:

  • Chest pain
  • Palpitations
  • Lightheadedness
  • Dyspnea
  • Dizziness
  • Pre-syncope
  • Heart failure or Syncope

NSVT in a Normal Heart

The following factors should be considered when testing for NSVT: general condition, age, previous medical history, history of syncopal episodes or sudden deaths in the family, proarrhythmic effects of drugs, and conditions like metabolic imbalance, electrolyte disturbances

For patients experiencing episodes of NSVT who are less than 40 years old, they should be tested for ischemic heart disease.

Individuals should be checked to rule out nonischemic causes of arrhythmia before they turn 40. These may include cardiomyopathies, valve disease, hypertension, and inherited channelopathies like catecholaminergic polymorphic ventricular tachycardia, long QT syndrome, Brugada syndrome, and other depolarisation syndromes that usually arise with polymorphic episodes.

NSVT doesn’t need any specific therapy if there is no pathology identified.
The symptoms just need to be controlled.

Monomorphic episodes of NSVT that is often seen in healthy individuals are usually caused by idiopathic ventricular outflow arrhythmias.

Diagnosis

When an individual is diagnosed with nonsustained ventricular tachycardia, it is essential for the doctor to perform a cardiac evaluation to check for underlying heart conditions.

Heart failure caused by dilated cardiomyopathy and coronary artery disease is the most common heart diseases associated with NSVT. NSVT is also usually seen in heart valve disease and hypertrophic cardiomyopathy.

These conditions can be tested through an echocardiogram. If an individual has a high risk of having coronary artery disease, a stress thallium test can also be used.

NSVT is sometimes due to cardiac conditions that are not linked with structural heart disease. Repetitive monomorphic ventricular tachycardia (RMVT) is an example of this kind of condition. RMVT is a congenital disease that is not so common. It involves the electrical system of the heart that doesn’t produce structural changes that can be detected through an echocardiogram. Doctors are only able to diagnose conditions of this kind that produce NSVT when they notice certain characteristics of arrhythmia through ECG.

Treatment

Goals of Treatment in NSVT

  1. Prevent malignant, sustained arrhythmias and sudden cardiac death
  2. Eliminate symptoms caused by NSVT

NSVT is a significant indicator of an underlying heart condition that may be present.
It is important to treat the underlying condition as soon as possible. NSVT doesn’t increase the risk of cardiac arrest if there are no underlying heart conditions found so treatment is not really necessary.

For heart failure and coronary artery disease, the risk of having a cardiac arrest is due to the left ventricular ejection fraction. The presence or absence of NSVT usually has nothing to do with it. To lessen the risk of having a cardiac arrest, consider an implantable defibrillator when the ejection fraction is decreased. The presence of NSVT for individuals with hypertrophic cardiomyopathy indicates a higher risk for sudden death. An implantable defibrillator is also strongly recommended by cardiologists especially if the family has a history of sudden death due to hypertrophic cardiomyopathy.

The presence of NSVT in valvular heart disease and mitral valve prolapse doesn’t increase the risk of cardiac arrest or sudden death. Nevertheless, these conditions still need to be treated.

Young people who don’t have any structural heart disease and are diagnosed with NSVT should be referred to a cardiac electrophysiologist, a specialist for heart rhythm, for them to be checked for RMVT or other congenital diseases that can possibly bring about this arrhythmia. Ablation therapy can often treat these kinds of arrhythmia.

NSVT cannot usually be treated with antiarrhythmic drugs because they tend to produce a lot of side effects and are often not very effective. There are drugs that can be used to control the symptoms and are relatively safe to intake.

Symptom Control

  • Nondihydropyridine Calcium Channel Blockers – This can be used to control the symptoms of NSVT especially for individuals who don’t have a structural heart disease
  • Beta Blockers – This a safe and well-tolerated method to control the symptoms of NSVT.
  • Antiarrhythmic medications – Calcium channel blockers and beta blockers are not able to suppress NSVT in some patients who experience frequent and highly symptomatic NSVT. Adding antiarrhythmic medications can help.
  • Catheter Ablation – Catheter ablation can be effective in eliminating or reducing the NSVT and its associated symptoms for patients who experience frequent monomorphic NSVT that cannot be controlled by medications, or for patients who are not able or who are not willing to take medications.

For individuals who are below 40 years old, check for heart conditions such as cardiomyopathies, hypertension, idiopathic ventricular tachycardia, valve disease, genetic channelopathies, and coronary artery anomalies. If any of these heart conditions are present, treat the underlying condition immediately. If there are no heart conditions, check for NSVT during exercise or during recovery. If NSVT is present, follow up with the patient, modify risk factors for coronary artery disease, excluding long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, and no antiarrhythmic therapy.
If the patient doesn’t have NSVT, follow up with the patient and only treat the symptoms.

For individuals who are above 40 years old, check for heart conditions such as hypertension, coronary artery disease, valve disease, cardiomyopathies, genetic channelopathies, and idiopathic ventricular tachycardia. If any of these heart conditions are present, treat the underlying condition immediately. If there are no heart conditions, check for NSVT during exercise or during recovery. If NSVT is present, follow up with the patient, modify risk factors for coronary artery disease, excluding long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, and no antiarrhythmic therapy.
If the patient doesn’t have NSVT, follow up with the patient and only treat the symptoms.