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Digitalis and Coronary Blood Flow

1938; SAGE Publishing; Volume: 38; Issue: 3 Linguagem: Inglês

10.3181/00379727-38-9839

1535-3702

Hiram E. Essex, J. F. Herrick, Edward J. Baldes, Frank C. Mann,

Heart Rate Variability and Autonomic Control

Considerable work has been done in an effort to evaluate the effect of digitalis on coronary blood flow. A wide variety of methods have been employed and the results on the whole have been contradictory. Gilbert and Fenn have reviewed the pertinent literature which preceded their report. These workers, after an extensive series of acute experiments in which they studied the effect of a number of preparations of digitalis on the outflow from the coronary sinus of the dog by use of the Morawitz cannula, concluded that digitalis preparations may exert a vasoconstrictor action on the coronary arteries. The use of the Morawitz cannula requires deep anesthesia, an open thorax and artificial respiration; consequently, the period of observation is necessarily relatively brief. For a number of years we have been studying coronary blood flow in the trained animal. It has been possible to measure the blood flow in one of the coronary arteries of the dog as often as desired, and in some experiments for as long as 2 weeks. Formerly we used the thermostromuhr method of Rein, but recently we have employed the method described by Baldes and Herrick, which makes use of a direct current heater. We have, therefore, been able to digitalize animals by divided doses in a manner comparable to the clinical method and at the same time observe the effect on the coronary blood flow. Seven dogs were prepared for these experiments. They were trained to lie quietly and subsequently the thermostromuhr unit was placed on the circumflex branch of the left coronary artery under general anesthesia and with sterile technic as described in a previous paper. Three of the animals fulfilled the following requirements sufficiently well to permit their use in this study: 1. The body Item perature and pulse rate of the dog must have remained within normal limits for at least 24 hours following the operation. 2. The coronary blood flow must have remained relatively constant for a like period. 3. Prior to injection of the drug the dog must have taken food without hesitation and behaved in all respects like a relatively healthy dog.