A patient develops sudden palpitation with HR 150/ min, regular. What could be the cause-

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 person's 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. Vagal maneuvers, such as the Valsalva maneuver, are often used as the initial treatment.If not effective and the person has a normal blood pressure the medication adenosine may be tried.If adenosine is not effective a calcium channel blockers or beta blocker may be used.[Otherwise synchronized cardioversion is the treatment. Future episodes can be prevented by catheter ablation. About 2.3 per 1000 people have paroxysmal supraventricular tachycardia.Problems typically begin in those 12 to 45 years old.Women are more often affected than men. Outcomes in those who otherwise have a normal hea are generally good. An ultrasound of the hea may be done to rule out underlying hea problems Symptoms may include palpitations, feeling faint, sweating, shoness of breath, and chest pain.Episodes sta and end suddenly Ref Harrison 20th edition pg 1456