Valvular Heart Disease and Hemodynamics
Quantifying stenosis and regurgitation
Valve questions reward a systematic approach. Aortic stenosis: integrate peak velocity, mean gradient, continuity-derived area (AVA = 0.785 × D² × VTI_LVOT ÷ VTI_AV), and dimensionless index (VTI ratio <0.25 indicates severe). Severe AS: peak velocity ≥4 m/s, mean gradient ≥40 mmHg, AVA ≤1.0 cm². Beware low-flow, low-gradient AS with reduced EF - use low-dose dobutamine to demonstrate contractile reserve and true severity - and paradoxical low-flow AS with preserved EF and a small, thick LV.
Mitral stenosis: planimetered area ≤1.5 cm² is severe; the pressure half-time method (220 ÷ PHT) is unreliable immediately after balloon valvuloplasty and in significant aortic regurgitation.
Regurgitation is graded with color jet size, vena contracta, PISA-derived EROA, regurgitant volume/fraction, and adjunct signs. Mitral: EROA ≥0.4 cm², vena contracta ≥0.7 cm, systolic pulmonary vein flow reversal. Aortic: vena contracta ≥0.6 cm, holodiastolic flow reversal in the descending aorta, pressure half-time <200 ms. Tricuspid: dense jet with hepatic vein systolic reversal.
Core hemodynamics: simplified Bernoulli ΔP = 4V²; RVSP = 4 × TR velocity² + right atrial pressure.
Traps: mean gradient is flow-dependent, peak gradient is not interchangeable with mean gradient, and a misaligned CW cursor underestimates severity.
Rule of thumb: never grade severity from one number - for any regurgitant lesion, find three concordant signs.