Acquired and Congenital Cardiac Pathology
Valvular disease severity
Severe aortic stenosis by peak velocity ≥4 m/s, mean gradient ≥40 mmHg, or valve area ≤1.0 cm²; low-flow low-gradient disease with reduced ejection fraction requires dobutamine stress, where a valve area ≤1.0 cm² with rising velocity confirms true severe stenosis. Severe mitral regurgitation: vena contracta ≥0.7 cm, PISA effective orifice area ≥0.4 cm², regurgitant volume ≥60 mL, and systolic pulmonary vein flow reversal. Severe mitral stenosis: valve area ≤1.0 cm² and mean gradient ≥10 mmHg at a heart rate of 60–80. Severe aortic regurgitation: vena contracta >0.6 cm, pressure half-time <200 ms, holodiastolic flow reversal in the descending aorta.
Myocardial and pericardial disease
Hypertrophic cardiomyopathy shows asymmetric septal hypertrophy with a ratio ≥1.3 and systolic anterior motion of the mitral leaflet; cardiac amyloid shows concentric thickening, biatrial enlargement, and relative apical sparing of longitudinal strain. Pericardial tamponade requires right-sided chamber collapse, a plethoric IVC, and respiratory variation in inflow velocities, not effusion size alone.
Congenital lesions
Know bicuspid aortic valve (raphe, eccentric jet, associated aortic dilation), atrial septal defect (sinus venosus defects accompany anomalous pulmonary venous return), ventricular septal defect, patent ductus arteriosus, coarctation, and tetralogy of Fallot (VSD, overriding aorta, RV outflow obstruction, RV hypertrophy).
Traps and rule of thumb
Eccentric wall-hugging jets are systematically underestimated by color Doppler. Never grade severity on one parameter. Rule of thumb: if two of three Doppler parameters agree, the severity call is safe; if they disagree, repeat with a second window and orthogonal view.