Effect of heart rate and perfusion pressure on coronary blood flow heterogeneity

Document Type

Article

Publication Title

FASEB Journal

Abstract

The effective delivery of nutrients in the coronary circulation is dependent not onlv on total coronary flow but also on how evenly flow is distributed within the heart Flow heterogeneity is potentially altered by adaptation to prevailing phssioiogicai conditions. We studied coronary flow heterogeneity in 13 mongrel dogs of cither sex, and weighing 19.5 - 27.8 kg. The left main coronary artery was isolated, cannulated, and perfused from a pressure-controlled reservoir. The Bundle of His was injected with 37% formaldehyde to produce AV-block. Heart rale (HR) was controlled by electrically pacing the anterior surface of the right \entnclc. In each dog, 6 microsphere injections ('"Gd. 57Co, 5lCr, "3Sn, B5Sr, Sc) were made at three perfusion pressures (PP) (60, 100, & 140 mmHg) at each of two HR (XO and 150 bpm). The left ventricular free-wall and intraventricular septum were cut into 6 rings from apex to base, 6 transmural layers, and 8 circumferential wedges tor a total of 288 pieces. Piece size averaged 0.4 (0.2 sd) g (n=3738). Normalized microsphere deposition density was calculated for each radionuclide in each piece and was assumed proportional to flow. The heterogeneity (sd of normalized deposition densities x 100) was significantly lower (MANOVA, p<0.03) at pressures of 60 (40.4±2..S) and 100 mmHg (41.8±2.5) than at the elevated PP of 140 mmHg (52 1±2.5). The heterogeneity was significantly (p<0.04) greater at a HR df 80 bpm (48.6±2.5) than at an elevated HR of 150 bpm (40.9±2.5). PP x HR interaction was not significant. We conclude that over at least a portion of the physiological range, vasodilation ma> improve nutrient delivery by reducing flow !ictcu>ueneit\. Supported bv American Heart Association, Missouri Affiliate.

Publication Date

12-1-1996

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