|
Three groups of factors limiting CFR: |
| 1. Increase of resting coronary blood flow due to increased myocardial oxygen demand as a result of: |
| • tachycardia |
| • increased myocardial contractility |
| • myocardial hypertrophy |
| 2. Decrease of maximal (hyperemic) coronary blood flow: |
| • epicardial coronary artery stenosis |
| • decrease mean aortic pressure = coronary perfusion pressure e.g. aortic insufficiency, exaggerate response to vasodilator agent |
| • wall thickening (remodeling) of resistance arterioles |
| • reduced density of arterioles |
| • cardiomyocyte hypertrophy |
| • perivascular fibrosis |
| • interstitial fibrosis |
| • endothelial dysfunction |
| • increased blood viscosity: policythemia, macroglobulinemia |
| • elevated LV diastolic pressure increasing extravascular compressive forces and resistance (particularly in subendocardial layer). |
| 3. Shift to the right in the pressure-flow relation through maximally dilated vessels due to an increase in zero flow pressure line: |
| • increased left ventricular diastolic pressure |
| • tachycardia |
| • myocardial hypertrophy |
Dimitrow et al. Cardiovascular Ultrasound 2005 3:18 doi:10.1186/1476-7120-3-18 |