Abstract:
Embolus occlusion of pulmonary arteries can result in elevated pulmonary blood pressures, often resulting in pulmonary hypertension (PH). Experimental observations have shown that small emboli (diameter <170μm) can have a disproportionate effect on pulmonary vascular resistance (PVR) compared with larger emboli for the same tissue occlusion. We present an anatomically-based theoretical model of perfusion in the acinar blood vessels designed to investigate changes in PVR following occlusion of arteries <500μm in diameter. The model predicts that emboli lodged near proximal capillary beds have a greater effect on PVR-regardless of their size - than emboli occluding 200μm diameter arterioles, with PH occurring for 10% less tissue occlusion. Capillary blood pressures are predicted to exceed 24 mmHg (levels initiating capillary wall damage) in regions of the capillary bed at approximately the onset of PH. This study focuses on the effect of mechanical obstruction alone; however we present simple models of vasoconstriction illustrating an increased impact on PVR.
