Fig 57.

68 year old lady who had atrial tachycardia 175-180/min with 2:1 block. She received three quinidine bisulphate tablets at midnight and another two, with 0.5 mg digoxin, two hours later. Fifteen minutes after that the tachycardia shown below developed, reverting spontaneously several times over the next four hours. There was no response to xylocaine.