RT Journal A1 Keyl AC T1 ATrial arrhythmias, digitalis, and potassium. JF A.M.A. Archives of Internal Medicine JO A.M.A. Archives of Internal Medicine YR 1959 FD June 1 VO 103 IS 6 SP 1013 OP 1014 DO 10.1001/archinte.1959.00270060165039 UL http://dx.doi.org/10.1001/archinte.1959.00270060165039 AB In this monograph, the authors take up in detail the disorders of atrial rhythm which may be induced by digitalis and characterize the particularizing disorder as paroxysmal auricular tachycardia (P. A. T.) with block. The delineation between P. A. T. with block and auricular flutter or paroxysmal auricular tachycardia is difficult, and great emphasis is placed on differentiating this hybrid disorder from conventional forms. The literature of the past half century has relegated P. A. T. with block to an area of dubious clinical significance and questionable origin. The authors present evidence, on the basis of the analyses of some one hundred fifty episodes of P. A. T. with block, that the disorder is rather common, having a distinct ECG pattern, and that in a majority of instances the etiology is related to digitalis therapy. The interplay between digitalis and body potassium is involved in this atrial arrhythmia much in