Supra Ventricular Tachycardia is abnormal fast heartbeat or heart rate of more than 100 beats per minute for reason other than stress, exercise or high fever. In some cases, the heart beat may cross 300 beats a minute.
It’s actually a very broad term that includes various forms of heart arrhythmias originating from the area above the ventricles (supraventricular) in the atria or AV node. That is why it’s named as supraventricular tachycardia. It is also called SVT, paroxysmal atrial tachycardia (PAT), atrial tachycardia or paroxysmal supraventricular tachycardia (PSVT).
Types of supraventricular tachycardia
Supraventricular tachycardia is of following types:
- Atrioventricular nodal reentrant tachycardia (AVNRT)
- Atrioventricular reciprocating tachycardia (AVRT)
- Atrial tachycardia
- Sinus tachycardia
- Inappropriate sinus tachycardia (IST)
- Multifocal atrial tachycardia (MAT)
- Junctional ectopic tachycardia (JET)
- Nonparoxysmal junctional tachycardia (NPJT)
Causes of SVT
In most cases, SVT occurs due to faulty electrical connections in the heart resulting in faster than normal heart beat. Other than this, SVT can be caused by following:
- Certain medicines like digoxin or the lung medicine theophylline.
- Genetics as some forms of SVT like Wolff-Parkinson-White syndrome run in families.
- Drinking large amounts of alcohol or caffeine
- Extreme stress
- Smoking lots of cigarettes etc.
Signs and symptoms of supraventricular tachycardia
SVT is mostly an episodic condition that can last for few or more seconds, minutes, hours or even days. In addition, it may occur once or several times a day, or only once or twice a month or year. It may come and go suddenly without making the person feel it. Most of the times, there are stretches of normal heart rates in between fast heartbeats.
Some people with SVT may have no symptoms at all and require no treatment. But in some cases SVT occurs frequently and is ongoing, particularly in patients with heart damage or other coexisting medical problems. In such cases, patient can complain of following symptoms:
- A fluttering in the chest
- A pounding or racing sensation in the neck
- Shortness of breath
- Chest pain
- Throat tightness
- Fainting (syncope) or near fainting
In infants and very young children, signs and symptoms may be difficult to identify. Sweating, poor feeding, pale skin and infants with a pulse rate greater than 200 beats per minute may have supraventricular tachycardia.
Diagnosis of SVT
Though in most of the cases SVT is not life threatening, but a person should contact a cardiologist or general physician as soon as possible on experiencing any symptoms.
The diagnosis of SVT involves thorough history taking of the patient by asking questions related to patient’s health and symptoms. This is followed by a physical examination to hear the heart sounds and record heartrate. An electrocardiogram (EKG, ECG) is then performed to measure and record the heart’s electrical activity. An ECG can show abnormalities indicating SVT in patients who are experiencing an episode of SVT at the time of ECG. But the real challenge is to identify abnormalities in ECG that suggest SVT, when the heart rhythm has returned to normal.
Other than ECG there are various other diagnostic methods that can be done to find out SVT like:
- Holter monitor
- Event monitor
- Implantable loop recorder
- Stress test
- Tilt table test
- Electrophysiological testing and mapping
Instant Diagnosis of SVT plays an important role in patient survival
Although it is not a life threatening condition but an episode of supraventricular tachycardia may cause unconsciousness or cardiac arrest. In addition to this, if the episodes become frequent and remain untreated for long, SVT can weaken the heart and lead to heart failure. In both the situations, it is very important to get an ECG done to make a diagnosis and start appropriate treatment right away. As there are so many other diagnostic methods too that can be done to find out SVT but the one that gives quick results is ECG. So ECG must be done for every patient with symptoms related to heart.
It is rightly said for heart conditions that an early shift to the hospital’s emergency department and a quick ECG can save a patient’s life.
Treatment of SVT
Treatment of SVT may include:
- Medicine to take during an episode of SVT
- Manoeuvres, such as the Valsalva manoeuvre
- Electric shock treatment called cardioversion
- Catheter ablation