Background: Coronary microvascular dysfunction has important prognostic implications. Several hemodynamic indices, such as coronary flow reserve (CFR), microvascular resistance (MR) and zero-flow pressure (Pzf) were used to establish the most reliable index to assess coronary microcirculation. Methods: Fifteen swine were instrumented with a flow probe, and a pressure wire was advanced into the distal LAD. Adenosine was used to produce maximum hyperemia. Microspheres were used to create microvascular dysfunction. An occluder was used to produce stenosis. Blood flow from the probe (Qp), aortic pressure (Pa), distal coronary pressure (Pd) and right atrium pressure (Pv) were recorded. Angiographic flow (Qa) was calculated using a time-density curve. Flow probe based CFR (CFRp) and angiographic CFR (CFRa) were calculated using Qp and Qa, respectively. Flow probe based normalized MR (NMRp) and angiographic normalized MR (NMRa) were determined using Qp and Qa, respectively, during hyperemia. Pzf was calculated using Qp and Pd. Results: Two series of ROC curves were generated: normal epicardial artery model (N-model) and stenosis model (S-model). The areas under the ROC curves for CFRp, CFRa, NMRp, NMRa, Pzf were 0.855, 0.836, 0.976, 0.956, 0.855 in N-model and 0.737, 0.700, 0.935, 0.889, 0.698 in S-model. Both NMRp and NMRa were significantly more reliable than CFR and Pzf in detecting the microvascular deterioration. Conclusions: Compared to CFR and Pzf, NMR provided a more accurate assessment of microcirculation. This improved accuracy was more prevalent when stenosis existed. Moreover, NMRa is potentially a less invasive method for assessing coronary microcirculation.
- Blood flow
- Cardiovascular imaging
- Coronary microvascular function
- Copyright © 2011, American Journal of Physiology - Heart and Circulatory Physiology