Direct cannulation of myocardial blood vessels without interfering with regional blood flow distribution, resting blood flow, or reactive hyperemia

Abstract

An in vivo technique of directly cannulating coronary arteries and veins for sampling blood and measuring hemodynamic parameters is described. The cannulation procedure was evaluated for its effects on regional myocardial blood flow (RMBF), transmural RMBF distribution, and reactive hyperemia. In a group of ten dogs, RMBF was measured by using radionuclide microspheres. Values for left anterior descending (LAD) perfusion zone (with catheter) and circumflex (CX) zone (no catheter) did not differ significantly (119 ± 14 mL/min/100 g v 123 ± 14 mL/min/100 g, respectively). Likewise, endocardialto-epicardial RMBF ratio was similar for the two areas (0.99 ± 0.06 and 1.04 ± 0.06, respectively). In five dogs, aortic and left ventricular pressures agreed closely with the LAD coronary artery pressure measured with the described catheter system. Arterial flow during rest and reactive hyperemia was measured in five additional dogs by using electromagnetic flow probes placed around the LAD and CX coronary arteries. During both rest and reactive hyperemia, flow was greater in the CX than in the LAD (65.46 ± 4.12 and 169.62 ± 9.04 in the CX v 30.24 ± 0.78 and 102.28 ± 5.38 in the LAD; P < 0.05 for both); however, the percentage change from rest to reactive hyperemia was similar for both vessels. In each perfusion zone, flow during rest and reactive hyperemia and the percentage change were not affected by cannulation. The effects of an infusion of adenosine (20 to 40 μg/min) into the pulmonary artery with and without the LAD coronary catheters (artery and vein) were tested in six other dogs. With adenosine, flow in the LAD increased from 35 to 110 mL/min without LAD cannulation, and from 35 to 86 mL/min with cannulation ( P > 0.05). Because it does not significantly affect coronary blood flow or transmural flow distribution, this cannulation technique allows drug infusion and blood sampling with minimal reduction in coronary conductance. It may therefore have applicability to the experimental study of myocardial blood flow and its responses to pharmacologic and physiologic interventions.