Heterogeneity of resting and hyperemic myocardial blood flow in healthy humans

Objective: Absolute myocardial blood flow (MBF) is not well-defined in larg e normal populations, and appears to be heterogeneous in both humans and an imals. These factors contribute to the difficulties in defining resting MBF to hibernating myocardium. We therefore assessed absolute baseline and hyp eremic MBF in a large population of normal humans. Methods: MBF was quantif ied by positron emission tomography with oxygen-15-labeled water at baselin e and during hyperemia induced by either adenosine or dipyridamole in 131 m en and 38 women, aged 21-86 (mean 46+/-12) years. MBF was corrected for wor kload using the rate-pressure product (RPP). Results: Uncorrected baseline MBF ranged from 0.590 to 2.050 (mean 0.985+/-0.230) ml/min/g (coefficient o f variation=27%), and corrected MBF from 0.736 to 2.428 (mean 1.330+/-0.316 ) ml/min/g (coefficient of variation=24%). MBF in the inferior region was s ignificantly (P<0.0001) lower than either the anterior or lateral regions. Baseline MBF in females was significantly (P<0.001) higher than in males. C onclusions: These results confirm the heterogeneity of MBF in normals and h ighlight the difficulty in establishing the lower limit of normal MBF. (C) 2001 Elsevier Science B.V. All rights reserved.