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Pitfalls in determining the severity of heart valve disease

Non-Invasive Imaging

TOPIC -1: Low flow, low gradient, Aortic stenosis presented by Raphael Rosenhek.
The independent parameters that determine outcome are velocity, mean gradient and aortic valve area (AVA). An important determinant of outcome is left ventricular ejection fraction (LVEF).
Patients with LVEF >50% (preserved function) may have normal flow or reduced flow, while those with LVEF < 50% (reduced function) may have low gradient or high gradient. Dobutamine echocardiography that documents “reduced contractibility” is associated with poor outcome.
Patients with poor function may have a greater amount of myocardial fibrosis.
Patients with aortic stenosis who have a reduced flow and reduced gradient have poor prognosis and aortic valve replacement (AVR) has a high operative mortality. Patients with reduced flow and high gradient have a poor prognosis if they do not have AVR. In general, all patients with high gradient do well with AVR. Patients with paradoxical low flow improve with AVR.

There is energy loss at the stenotic aortic valve that results in pressure loss. A very short distance from the valve, some of the energy (pressure) loss is converted back to kinetic energy and thus, some of the pressure loss is regained, resulting in “pressure recovery”
Thus,in AS, the gradient is highest at the level of the valve, which is where the velocity is measured and beyond the obstruction, the gradient is similar to that measured by cardiac catheterization. Other factors that affect the calculations are the size of the aortic root and jet eccentricity.
The group from Canada have provided a method of correcting the size of the aorta by calculating the energy loss index (ELI). Aortic valve area index (AVAI) by ELI and by cardiac catheterization show that ELI and AVAI of <0.6 cm2/m2 signify servere AS. At the present time, there is no data showing the relationship of ELI to results of aortic valve replacement (AVR).

MR in AS maybe primary or secondary. Primary MR is diagnosed by changes in mitral valve (MV) morphology and the colour flow MR jet. In secondary MR, survival varies inversely with grade of MR. Outcomes in patient with MR vary with (a) etiology of MR; (b) severity of MR; (c) remodelling after valve replacement; and (d) remodelling is influenced positively with successful revascularization. With TAVI, about 50% of MR is improved.
Valve prosthesis –patient mismatch was first described in 1978. All prosthetic heart valves (PHV) are smaller than the normal valve and thus, all patients have prosthesis-patient mismatch (PPM). In most patients, PPM is mild to moderate in severity. PPM severity should be judged by the same criteria as aortic stenosis: Mild is: EOAi of>0.9cm2/m2; moderate is EOAi of >0.6 cm2/m2; severe is ≤0.6 cm2/m2; very severe or critical is EOAi of <0.4cm2/m2. PPM should be evaluated by echocardiography/Doppler at 2-4 weeks after AVR and also at 6-12 months post-AVR. Severe PPM has some untoward clinical events but its role as an independent predictor of cardiac mortality and its cause is unproven at present. Prediction of severity of PPM is problematic.





Pitfalls in determining the severity of heart valve disease

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.