Abstract 16888: Computational Simulations of Coronary Artery Flow in Supravalvular Aortic Stenosis
Introduction: Supravalvular aortic stenosis (SVAS) and aortic coarctation (CoA) are sources of ventricular afterload, which can lead to a mismatch between coronary artery flow (CF) and cardiac oxygen consumption. A much higher incidence of myocardial ischemia in patients with SVAS compared with CoA is observed even without coronary artery anomalies. A characteristic ascending aortic pressure waveform with a precipitous drop in diastole is noted in SVAS, which potentially decreases coronary perfusion pressure. We hypothesized that patients with SVAS are hemodynamically prone to myocardial ischemia even without coronary artery anomalies.
Methods: To quantify CF in patients with SVAS, we developed a lumped parameter model for adults weighing 70kg, based on the 3-element windkessel model coupled with the time-varying elastance model of ventricles. CF was simulated using the waterfall model. Left ventricular systolic pressure volume area (PVA) was calculated to predict cardiac oxygen consumption. SVAS and CoA models have 80% stenosis in cross sectional area at ascending and descending aorta, respectively.
Results: Cardiac output was 5.62L/min in a control model, 5.57L/min in SVAS and 5.59 L/min in CoA. Ascending aortic pressure was 116/68mmHg in control, 157/69mmHg in SVAS and 125/68mmHg in CoA. Pressure gradient between ascending and descending aorta was 48mmHg in SVAS and 9mmHg in CoA. PVA was markedly elevated in SVAS (Control 8366, SVAS 10681, CoA 8822 mmHgml/beat). CF only mildly increased in SVAS (Control 73.6,SVAS 77.5,CoA 74.4 ml/min per 100g of left ventricle, Figure). Coronary flow to PVA ratio was the lowest in SVAS(Control 1.18*10-4,SVAS 0.966*10-4,CoA 1.12*10-4 mmHg-1 per 100g of left ventricle). PVA of 8653 mmHg/beat and CF of 74.0 ml/min were predicted in 40% stenosis in SVAS, which corresponds to 80% stenosis in CoA in terms of ascending aortic systolic pressure.
Conclusions: Computational simulations predict a higher ascending aortic pressure in SVAS compared to CoA with the same degree of stenosis. This resulted in a mismatch between CF and cardiac oxygen consumption in patients with SVAS, which may explain a higher risk of myocardial ischemia in this population.
- © 2012 by American Heart Association, Inc.