Atrial flutter, is caused by a re-entry rhythm in the atria, with a regular atrial rate often of about 300 beats per minute. On the ECG this appears as a line of "sawtooth" waves preceding the QRS complex. The AV node will not usually conduct 300 beats per minute so the P:QRS ratio is usually 2:1 or 4:1 pattern, (though rarely 3:1, and sometimes 1:1 where class IC antiarrhythmic drug are in use). Because the ratio of P to QRS is usually consistent, A-flutter is often regular in comparison to its irregular counterpart, atrial fibrillation. Atrial flutter is also not necessarily a tachycardia by definition unless the AV node permits a ventricular response greater than 100 beats per minute. AV nodal reentrant tachycardia (AVNRT) involves a reentry circuit forming next to, or within, the AV node. The circuit most often involves two tiny pathways one faster than the other. Because the node is immediately between the atria and ventricle, the re-entry circuit often stimulates both, appearing as a backward (retrograde) conducted P-wave buried within or occurring just after the regular, narrow QRS complexes. Atrioventricular reciprocating tachycardia (AVRT), also results from a reentry circuit, although one physically much larger than AVNRT. One portion of the circuit is usually the AV node, and the other, an abnormal accessory pathway (muscular connection) from the atria to the ventricle.
Episodes can be treated when they occur by Valsalva maneuver, adenosine injection or taking a AV node blocking agent as pill-in-pocket, but regular medication may also be used to prevent or reduce recurrence. While some treatment modalities can be applied to all SVTs, there are specific therapies available to treat some sub-types. Effective treatment consequently requires knowledge of how and where the arrhythmia is initiated and its mode of spread.Lifestyle changes, medication and heart procedures may be needed to control or eliminate the rapid heartbeats and related symptoms.SVTs can be categorised by whether the AV node is involved in maintaining the rhythm. If it is, manoeuvres slowing conduction through the AV node will terminate it. If it is not, AV nodal blocking maneuvers will not terminate it, but resulting temporary suppression of the AV node is still useful to unmask the underlying abnormal rhythm.Acute attacks of supraventricular tachycardia are treated with Esmolol (i.v.). Society and culture
Notable cases of SVT:

Bobby Julich, American professional road cyclist, third-place finisher in the 1998 Tour de France, bronze medalist in the 2004 Summer Olympics
Tayyiba Haneef-Park, American volleyball competitor in the 2008 Summer Olympics
Tony Blair, former Prime Minister of the United Kingdom
Anastacia Lyn Newkirk, American singer-songwriter. Rebecca Soni, American Gold Medal Olympic swimmer
Dana Vollmer, American Gold Medal Olympic swimmer
Neville Fields, Australian football player
Paul Bearer, wrestling manager
Nathan Cohen, New Zealands two-time world champion and Olympic champion rower, was diagnosed with SVT in 2013 when he was 27 years old.