A young lady complains of sudden onset of palpitations, extreme weakness and sweating. On examination, she was found to have B.P. 90/70 with a regular pulse rate of 180/minute. Her symptoms disappeared after vomitting but she complained of polyuria. The most likely diagnosis is
Primary thyrotoxicosis
Acute anxiety state
Paroxysmal atrial tachycardia
Paroxysmal atrial flutter