Four groups of dog hearts were studied by corrosion injection procedures in an attempt to correlate atrioventricular conduction with perfusion of the septum. Group 1 (controls) consisted of 30 normal hearts injected to demonstrate the normal arterial blood supply of the interventricular septum. Group 2 consisted of 30 hearts of dogs sacrificed 24 or 48 hours following ligation of the anterior septal artery. A prolonged P-R interval was present in each dog; injection studies showed complete absence of arterial filling of the central septal area. Group 3 consisted of 5 hearts; these dogs were sacrificed at the time the P–R interval began to revert to the value prior to ligation of the anterior septal artery or had been prolonged for more than 7 days. Injection studies demonstrated some degree of retrograde collateral filling of the anterior septal artery. Group 4 consisted of 15 hearts in which the P–R interval had returned to the value prior to ligation of the anterior septal artery (4 to 8 weeks). Injection studies showed complete retrograde collateral filling of the anterior scptal artery and its branches. From these studies it appears that there is a definite correlation between changes in atrioventricular conduction and perfusion of the interventricular septum of the dog.
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