What is the difference between supraventricular arrhythmias (SVT) like atrial flutter and atrial fibrillation?
It is normal for your heart rate to change during the day, depending on your activity level. For example, you can expect your heart rate to increase when you're exercising, but not when you are sitting still.
Any kind of abnormal rhythm or heart rate is called an arrhythmia. Fast, abnormal heart rhythms, with rates over 100 bpm, are called tachyarrhythmias. Supraventricular tachycardia (SVT) is a general term for any fast heart rhythm coming from above the ventricles.
Anyone can develop an arrhythmia, even a young person without a previous heart condition. However, arrhythmias are most common in people over 65 who have heart damage caused by a heart attack, cardiac surgery, or other conditions. Common SVTs include:
- Atrial fibrillation
- Atrial flutter
- Atrioventricular nodal re-entrant tachycardia (AVNRT)
- Wolff-Parkinson-White syndrome (WPW)
(AF or AFib) is the most common SVT, affecting more than 328,000 Australians1. It is one of the causes of stroke, especially among elderly people2. During AF, the heartbeat produced by the atria is irregular and rapid—typically more than 300 bpm—where muscle fibres in the heart twitch or contract. With such a fast heart rate, the heart does not pump efficiently. This may cause blood to pool and can lead to the formation of clumps of blood called blood clots. A stroke can occur if a blood clot travels from the heart and blocks a smaller artery in the brain (a cerebral artery). About 15% of strokes happen in people with atrial fibrillation.
1. Ball J et al (2015), “Estimating the current and future prevalence of atrial fibrillation in the Australian adult population”, Med J Aust 2015; 202 (1): 32-35
2. Wann SL, Curtis AB, January CT, et al. 2011 ACCF/AHA/HRS Focused Update on the Management of Patients With Atrial Fibrillation (Updating the 2006 Guideline). Circulation. 2011;123:104-123
Atrial Arrhythmia Patient
When I was in the Marines, I woke up in the hospital after I passed out with a heart rate of 200 plus. They said I had an arrhythmia called AV nodal re-entrant tachycardia.
Bob Melcher, Patient
AV Nodal Re-entrant Tachycardia (AVNRT)
These pathways are present at birth. People of all ages, including infants, can experience the symptoms related to Wolff-Parkinson-White syndrome. Episodes of a fast heartbeat often first occur when people are in their teens or early 20s.
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