Mechanism of Cardiogenic Shock

• The mechanism of shock following acute myocardial infarction is still controversial. Xumerous investigators have applied tech-niques such as: (a) ligation of the different branches of the coronary arteries,1"4 (b) chemical or traumatic methods to produce myoeardial injury/ " and (c) introduction of einbolizing particles into the coronary circu-lation. " The results are conflicting, largely because the methods used to modify the cor-onary circulation necessitated either the di-rect approach of opening the chest for coro-nary ligation or einbolization, or the indirect approach of injecting einbolizing particles through an aortic catheter in the vicinity of the coronary ostia. Although the latter pro-cedure may be performed in animals Avithout opening the thorax, it not only lacks selec-tivity of distribution of the einbolizing par-ticles in the coronary vascular bed, but spills a considerable share of the emboli into the systemic, circulation. The method we have used in the present study circumvents previous difficulties be-cause it. permits us to eatheterize selectively individual coronary arteries7 without opening the chest or interfering with perivaseular nerves and to inject embolizing agents into specific coronary vascular beds. Methods AVe studied 2-t adult mongrel dogs (20 to 25 Kg.), anesthetized with morphine (3 ing./.Kg1.) and 0.25 nil./Kg. of a combination of equal vol-umes of Dial-uretliane solution (100 and 400 ing./ ml., respectively) and of pentobarbital sodium (60 mg./ml.)