Comparison of digitalis doses in auricular flutter on the auricle and A-V conduction.

Abstract

Mackenzie, 1 Turnbull, 2 and Lewis 3 showed that auricular flutter passed into fibrillation during the administration of digitalis. Lewis showed that this was due to the action of digitalis upon the auricle. He also pointed out that another useful action of digitalis in auricular flutter, particularly in cases with 2:1 A-V block, was to slow the ventricle by increasing the A-V block.

We have seen 16 cases of auricular flutter with 2:1 A-V block occurring with various etiological and structural types of heart disease. The first 10 of these cases were given digitalis by the body weight method in 4 doses, receiving in the first 24 hours 0.15 cat unit of digitalis per pound. It was noticed that while all except two of these cases responded with a slow ventricular rate, due to increasing A-V block, none of them developed notable changes in the circus movement rates or developed auricular fibrillation until substantially larger doses of digitalis were given.

The last 6 cases have been studied differently. During a control period of one week, it was determined that the flutter was of the permanent type, and that a persistent 2:1 A-V block was present. At least 2 weeks after receiving any digitalis medication a standardized preparation of digitalis leaf (0.1G=1 cat unit) was given by mouth at intervals never more frequent than every 6 hours. Observations were made before each successive dose, and the amount of the drug was noted which had been taken at the time of the following changes : (a) the first increase of A-V block; (b) the first distinct change in the circus movement rate (c) the onset of auricular fibrillation; (d) the first sign of any toxic symptoms.