SVT (Atrioventricular Nodal Reentrant Tachycardia - AVNRT): This is the most common type of SVT, accounting for about 60% of cases. It occurs when there is an abnormal electrical pathway in the heart, leading to rapid heart rate.

Atrioventricular Reentrant Tachycardia (AVRT): This includes orthodromic AVRT, which is another common form of SVT, and accounts for about 30% of cases. It involves an accessory electrical pathway between the atria and ventricles.
Atrial Flutter: Although not technically an SVT, atrial flutter can present similarly and is often considered in the differential diagnosis. It is characterized by a rapid but regular atrial rhythm.
Atrial Fibrillation: This is the most common type of arrhythmia and can sometimes be mistaken for SVT due to its rapid and irregular heart rate.

Ventricular Tachycardia (VT): Although VT is a ventricular arrhythmia, it can be mistaken for SVT and is critical to diagnose promptly due to its potential to deteriorate into ventricular fibrillation, which is life-threatening.
Wolff-Parkinson-White (WPW) Syndrome: A condition where an accessory electrical pathway between the atria and ventricles can cause SVT but also poses a risk of developing into a life-threatening arrhythmia.
Cardiac Tamponade: Although not an arrhythmia, cardiac tamponade can cause tachycardia and must be considered in the differential diagnosis due to its high mortality rate if not treated promptly.

Junctional Tachycardia: A rare form of SVT originating from the AV junction, which can be due to various causes including digitalis toxicity or cardiac disease.
Mahaim Fiber Tachycardia: A rare type of SVT involving an accessory pathway that can conduct anterogradely, often associated with a distinct electrocardiographic pattern.
Lown-Ganong-Levine (LGL) Syndrome: A rare condition characterized by an accessory pathway that can cause SVT, similar to WPW syndrome but without the characteristic delta wave on the ECG.