Aortic stenosis: no more hemodynamic cardiac catheterization!

Revisiting the simplified bernoulli equation

BACKGROUND

The assessment of the severity of aortic valve stenosis is done by either invasive catheterization or non-invasive Doppler Echocardiography in conjunction with the simplified Bernoulli equation. The catheter measurement is generally considered more accurate, but the procedure is also more likely to have dangerous complications.

OBJECTIVE

The focus here is on examining computational fluid dynamics as an alternative method for analyzing the echo data and determining whether it can provide results similar to the catheter measurement.

METHODS

An in vitro heart model with a rigid orifice is used as a first step in comparing echocardiographic data, which uses the simplified Bernoulli equation, catheterization, and echocardiographic data, which uses computational fluid dynamics (i.e., the Navier-Stokes equations).

RESULTS

For a 0.93cm(2) orifice, the maximum pressure gradient predicted by either the simplified Bernoulli equation or computational fluid dynamics was not significantly different from the experimental catheter measurement (p > 0.01). For a smaller 0.52cm(2) orifice, there was a small but significant difference (p < 0.01) between the simplified Bernoulli equation and the computational fluid dynamics simulation, with the computational fluid dynamics simulation giving better agreement with experimental data for some turbulence models.

CONCLUSION

For this simplified, in vitro system, the use of computational fluid dynamics provides an improvement over the simplified Bernoulli equation with the biggest improvement being seen at higher valvular stenosis levels.

Calcific aortic stenosis: new pathophysiologic insights and possible new medical therapy

Aortic stenosis is a progressive disease of aging with serious complications. A common disease of the elderly, it may inexorably progress to stenosis. Recent retrospective studies have correlated risk factors commonly associated with coronary and vascular atherosclerosis with an accelerated rate of aortic valve stenosis. Although hydroxymethyl glutaryl co-enzyme A reductase inhibitor (statin) treatment therapy has been shown to delay the rate of progression of valvular aortic stenosis, the salutary mechanism of the statin may be cholesterol-lowering and/or anti-inflammatory. Further prospective studies are warranted to investigate the mechanism and medical therapy of aortic sclerosis and stenosis.