Affiliations: Cardiovascular Institute, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA | Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA | Department of Bioengineering, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
Note: [] Address for correspondence: Dr. John J. Pacella, Cardiovascular Institute, Department of Medicine, University of Pittsburgh, S570 Scaife Hall, 200 Lothrop Street, Pittsburgh, PA 15213, USA. Tel.: +1 412 647 5840; Fax: +1 412 647 4227; E-mail: pacellajj@msx.upmc.edu.
Abstract: We have shown that drag-reducing polymers (DRP) reduce microvascular resistance and improve myocardial perfusion during coronary stenosis. We used myocardial contrast echocardiography (MCE) and mathematical modeling to define the DRP microvascular effects. A non-flow-limiting left anterior descending (LAD) stenosis was created in 8 dogs. Intramyocardial blood volume, RBC velocity and flow in the LAD and circumflex (CX) beds were obtained from MCE at baseline, and in hyperemia, stenosis, hyperemia + stenosis, and hyperemia + stenosis + DRP. Microvascular resistances were calculated from a lumped-parameter model. During stenosis + hyperemia, LAD bed microvascular resistance increased (p<0.015), and capillary volume (p<0.002) and red cell velocity (p<0.0004) decreased relative to baseline. With DRP, during stenosis and hyperemia, LAD bed microvascular resistance decreased (p<0.04); there was an increase in capillary volume (p<0.007), RBC velocity (p<0.006), and flow (p<0.05). Decreased model-computed capillary resistance accounted for the reduction in LAD bed resistance after DRP. We conclude that DRP improve flow reserve during coronary stenosis by modulating capillary resistance. Primary modification of the rheological properties of blood to affect capillary resistance is a novel approach for the treatment of acute coronary syndromes.
