What is tachycardia?
Tachycardia refers to a heart rate more than 100 beats per minute (bpm) at rest. Paroxysmal supraventricular tachycardia (PSVT) or supraventricular tachycardia or SVT is an abnormal heart rhythm (dysrhythmia) with an accelerated heart rate caused by abnormal electrical impulses arising from the upper chambers of the heart above the ventricles (atria) or atrioventricular node (AV node). The heartbeat is generated as electrical impulses from a structure called the sinoatrial node (SA node). These impulses travel to the upper chambers of the heart (atria) and through the AV node to the lower chambers (ventricles). SVT generally arises due to abnormal impulse generation in the atria. The rapid heart rate interferes with the pumping efficiency of the heart leading to decreased ventricular filling, cardiac output, and low blood pressure. SVT is the most common symptomatic dysrhythmia seen in children. Children with congenital heart disease are at an increased risk of SVT. SVT is typically not life-threatening unless the person has other heart disorders. Untreated SVT, however, may progress to cause life-threatening complications in some people.
What are the types of supraventricular tachycardia?
There are three major types of supraventricular tachycardia (SVT):
- Atrial fibrillation (AF): It is the most common type of SVT. The risk of AF increases with age. It is more common in men and people with other heart conditions, diabetes, obesity, and obstructive sleep apnea. It occurs as a result of too much electrical signals coming from the atrium, causing rapid and fast heartbeat with irregular rhythm.
- Paroxysmal supraventricular tachycardia (PSVT): It is a type of cardiac arrhythmia resulting from atrioventricular (AV) nodal re-entrant tachycardia (AVNRT) or from an accessory pathway as part of Wolff-Parkinson-White (WPW) syndrome. PSVT starts and stops abruptly. It can occur at any age. In AVNRT, a small extra pathway exists in or near the atrioventricular (AV) node. The electrical impulses entering this pathway travel in a circular pattern making the heart abruptly beat fast.
- Atrial flutter and atrial tachycardia: They are caused by a short circuit in the right atrium, which makes the heart beat at 300 beats per minute (bpm), whereas the lower chambers beat at a lower rate. It most commonly affects the elderly and people with other heart conditions.
The precipitating factors for supraventricular tachycardia (SVT) include the following:
- Sepsis (body's reaction to an infection)
- Caffeine and nicotine
- Physical and emotional stress
- Other heart diseases
- Lung diseases
- Myocarditis (inflammation of the heart muscles)
- Excessive alcohol consumption
- Obstructive sleep apnea
In general, supraventricular tachycardia (SVT) is rarely life-threatening. Many patients are often asymptomatic. Patients may experience the following symptoms:
If a person experiences any of the above symptoms, they must seek urgent medical attention.
The initial diagnosis is based on the patient's medical history and physical examinations. Further diagnostic tests to monitor heart function and rule out the cause are also advised by the doctor, which are as follows:
What is the treatment for supraventricular tachycardia?
Some supraventricular tachycardias (SVTs) are asymptomatic and do not need any treatment. The doctor would advise treatment based on the symptoms and cause of SVT. Treatment involves the following:
- Hemodynamic stability (vital signs) of the patient must be maintained.
- The doctor may consider immediate cardioversion if the patient is unstable.
- The doctor may consider vagal maneuvers in case of short-term management.
- The doctor may give a carotid massage.
- The doctor may consider giving intravenous (IV) adenosine if vagal maneuvers are ineffective.
- The doctor may consider catheter ablation.
- The doctor may give oral beta blockers or calcium channel blockers for long-term management.
In addition to the treatments, SVTs could be avoided by following proper lifestyle changes to maintain normal functioning of the heart:
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Gugneja, Monika. "Paroxysmal Supraventricular Tachycardia." Medscape.com. Apr. 25, 2017. <https://emedicine.medscape.com/article/156670-overview>.