Non-sustained ventricular tachycardia or NSVT is a type of ventricular tachycardia that stops on its own within thirty seconds. Sustained ventricular tachycardia is considered more deadly than non-sustained ventricular tachycardia; however the latter is more prevalent.
Non-sustained ventricular tachycardia refers to a bout of ventricular tachycardia which elicits a minimum heart rate of 120 beats per minute, persists for at least 3 beats and lasts for less than half a minute. In most cases, non-sustained ventricular tachycardia does not result in any symptoms, or it may only cause palpitations. Sometimes, NSVT may be accompanied by dizziness or lightheadedness, and in rare instances, loss of consciousness.
As non-sustained ventricular tachycardia generally does not cause any harmful symptoms, the condition is usually found out during an ECG or a routine cardiac checkup.
Non-sustained ventricular tachycardia can sometimes produce bothersome signs and symptoms. It also acts as an indicator of possible underlying occurrence of life-threatening cardiac conditions.
Non-sustained ventricular tachycardia by itself does not cause cardiac arrest or ventricular fibrillation. Hence, doctors do not consider the condition to be deadly. However, as it offers cluesto a possible case of some other severe heart disease, physicians give great importance to a diagnosis of NSVT.
In case non-sustained ventricular tachycardia is detected during routine cardiac tests, then doctors will go for further diagnostic procedures to detect the presence of pre-existing severe cardiac diseases.
Cardiac failure related to dilated cardiomyopathy and CAD or coronary heart disease are most often associated with non-sustained ventricular tachycardia. Non-sustained ventricular tachycardiahas also been observed to occur along with hypertrophic cardiomyopathy as well as heart valve disease, particularly mitral regurgitation, aortic stenosis, and mitral valve prolapse. An echocardiogram and other screening procedures will be recommended by doctors to check for the presence of the above diseases. Individuals with elevated risk to CAD may also be asked to undergo a stress thallium test to confirm the occurrence of CAD.
Non-structural cardiac diseases are conditions that do not change the heart anatomy. Two types of such non-structural cardiac disorders can also cause repetitive and frequent bouts of non-sustained ventricular tachycardia. They are CPVT or catecholamine-sensitive polymorphic ventricular tachycardia, and RMVT orrepetitive monomorphic ventricular tachycardia.Both these heart conditions are rare and occur from birth. They affect the cardiac electrical system and cause no structural alterations that can be detected on an echocardiogram.
Treatment for non-sustained ventricular tachycardia
The occurrence of non-sustained ventricular tachycardia is usually a sign of some underlying heart disease. In case such pre-existing cardiac disorders are diagnosed, then they need to be treated as per standard treatment procedures. If no cardiac condition is detected, then typically no treatment is required as non-sustained ventricular tachycardiadoes not pose any substantial risks to cardiac arrests.
Treatment of NSVT itself: Treatment of non-sustained ventricular tachycardia may become necessary if it is accompanied by frequent and problematic symptoms.
- It is not that easy to treat NSVT. Antiarrhythmic drug therapy is moderately effective. However, it can result in a lot of abnormal side effects.
- Doctors typically opt for beta blockers and then follow it up with calcium channel blockers. These medications not only help in alleviation of NSVT symptoms, but are also comparatively safer.
- If the symptoms persist despite the above treatment options, then patients need to consult a cardiac electro-physiologist. He/she may carry out ablation therapy to cure non-sustained ventricular tachycardia.Alternatively, the electro-physiologists may opt for antiarrhythmic medications and try to decrease the accompanying risks as much as possible.
Treatment of NSVT-associated heart conditions: Some of the common cardiac conditions associated with non-sustained ventricular tachycardia are treated in the following ways:
- The occurrence of NSVT along with hypertrophic cardiomyopathy poses a slightly increased risk of unexpected death. Hence, doctors may opt to prevent it by going for an implantable defibrillator, particularly if the patient has a family history of cardiac conditions, or is suffering from problematic symptoms.
- Non-sustained ventricular tachycardia patients may also be at greater risk to sudden fatality from cardiac arrhythmias, especially those at greater risk to cardiac failure and/or CAD. It may also be noted that in such instances the susceptibility to cardiac arrest is usually associated with left ventricular ejection fraction, rather than absence or presence of NSVT. Doctors will opt for an implantable defibrillator to decrease the risk; more so in cases where the ejection fraction is considerably lowered.
- Young individuals suffering from excessive episodes of non-sustained ventricular tachycardia, but who do not elicit any structural cardiac diseases, should consult a heart electro-physiologist for evaluation of CPVT or RMVT.
- It is also important to remember that the presence of non-sustained ventricular tachycardia does not alter the outcome of valvular cardiac disease such as mitral valve prolapse. Patients suffering from such heart conditions are treated in a manner that is irrespective of the presence or absence of NSVT.