Myocardial flow distribution. II: Empty beating heart, ventricular fibrillation and cardiac arrest

Myocardial oxygen consumption (MV̇O₂) and coronary blood flow (CBF) distribution were studied in 21 isolated, metabolically supported dog hearts. Measurements of MV̇O₂ and CBF distribution were carried out in three different experimental conditions : empty beating heart (EBH), ventricular fibrillation (VF) and high potassium-induced cardiac arrest (CA). MV̇₂ was approximately the same in EBH and VF (4.09 + 0.77 and 4.28 + 0.68 ml O₂ min^-1 100 g^-1 respectively), and significantly lower in the group with CA (2.40 +0.18 ml O₂ min^-1 100 g^-1, P < 0.05). Total CBF showed no significant differences among the three groups (84 + 7 ml/min in EBH; 78 + 7 ml/min in VF and 83 + 7 ml/min in CA). Subendocardial CBF per unit of tissue mass was significantly lower in hearts with VF (0.43 + 0.01 ml min^-1 g^-1, P < 0.05) when tested against the other two groups of experiments (0.69 + 0.03 ml min^-1 g^-1 in EBH and 0.65 + 0.04 ml min^-1 g^-1 in CA). This was also reflected in the endo/epi ratio, that was significantly lower in VF (1.41 + 0.07, P < 0.05) with respect to the other two groups (2 + 0.09 in EBH and 2.21 + 0.07 in CA).