<prompt> A patient develops sudden palpitation with HR 150 min, regular. What could be the cause -PSVTSinus tachycardiaVentricular tachycardiaAtrial flutter with block  <response>: Paroxysmal supraventricular tachycardia PSVT is a type of supraventricular tachycardia.Often people have no symptoms.Otherwise symptoms may include palpitations, feeling lightheaded, sweating, shoness of breath, and chest pain.Episodes sta and end suddenly The cause is not known.Risk factors include alcohol, caffeine, nicotine, psychological stress, and Wolff-Parkinson-White syndrome which often is inherited from a persons parents. The underlying mechanism typically involves an accessory pathway that results in re-entry.Diagnosis is typically by an electrocardiogram ECG which shows narrow QRS complexes and a fast hea rhythm typically between 150 and 240 beats per minute Ref Harrison 20th edition pg 1435 