My mother age 54 years , weight 44kg, height 5'1", is have 180+ heart rate beat for few minutes ( happened 2 times in 2 months) and took water and calmed down. Visited doctor and he said could be psvt. ECG is normal, thyroid is ok. Please guide , any test which can diagonise. What are likely treatments? Can it be cured by medicine, as i have read that mnual physical prevention is only way. Please throw some light . Moreover, Is it serious heart threat for her considering her age?