The Effect of Acute Occlusion of the Coronary Sinus on the Coronary Circulation

The changes in the coronary circulation, which are precipitated by the acute occlusion of the coronary sinus, have been investigated. In normal animals, retrograde blood emerging from the peripheral segment of a ligated and transected circumflex coronary artery is small in quantity, and arterial in nature, signifying an insignificant interarterial collateral flow. After the coronary sinus is arterialized, the retrograde circumflex arterial blood increases in quantity and is venous in nature. We now studied the effect on the coronary circulation of elevating the pressure of the coronary sinus by ligation, without arterialization. Under this condition, coronary sinus pressure rises, and retrograde circumflex flow is of normal quantity, but is also venous in nature. The source of this blood from the capillary bed and its directions of flow are discussed. OUR previous studies1 on the retrogradeblood flow, and the oxygen content ofthis blood, obtained from the distal end of the ligated and transected circumflex coronary artery in dogs, revealed the normal collateral circulation to be insignificant, which directly confirmed previous work reported by Wiggers and Green.2 This retrograde flow averaged 1.7 cc. per minute, and the blood was highly oxygenated indicating its origin from neighboring arteries. I t therefore represented a measure of intercoronary collateral anasto-motic flow. These findings were significantly altered in dogs in which the coronary sinus had been arterialized for four to eight weeks.3 In these animals, the retrograde circumflex arterial flow increased markedly, averaged 12.2 cc. per minute, and was venous in nature. Since the pressure within the coronary sinus was elevated to systemic levels, and its blood was highly oxygenated, the venous nature of the retrograde circumflex arterial flow pointed towards a retroperfusion of the myocardial capillary bed. These observations stimulated our curiosit