Overview
Chronic valve lesions have independent Mild, Moderate and Severe grades. Acute severe MR and acute severe AR remain acute severe phenotypes. The grade is a selected teaching state: it is not inferred from a single pressure wave, v-wave height or calculated area.
Chronic cavity remodeling, immediate loading and recirculating stroke volume are separate mechanisms. Mild/moderate isolated lesions do not receive assumed chronic ventricular enlargement; actual filling and recirculating flow can still change the computed volume excursion.
Illustrative severity parameters
Burden interpolates reference filling, flow, rate and BP from normal toward the severe endpoint. These are model coefficients, not guideline grading cutoffs.
| Grade | Burden | MR / AR / TR fraction | PR fraction |
|---|
| mild | 0.14 | 0.15 | 0.12 |
|---|
| moderate | 0.45 | 0.35 | 0.30 |
|---|
| severe | 1 | 0.52 | 0.45 |
|---|
Pressure gradients and timing
Stenosis raises pressure upstream of the obstructed valve. Outflow gradients change with flow squared and lesion burden. MS/TS pressure separation changes with the amount of inflow and filling time. The PA contour solver preserves mean PA = wedge + PVR × pulmonary flow; higher wedge alone does not create higher PVR.
Gradient shading uses simultaneous upstream and downstream pressure differences during the relevant systolic or diastolic phase. It is pressure-gradient area on a time plot, not a measure of acoustic murmur loudness or Doppler velocity. Peak-to-peak and mean instantaneous gradients are different quantities.
Regurgitation and forward flow
Total chamber stroke volume can exceed forward stroke volume because some blood recirculates. In the LV model, combined MR and AR use the net fraction 1 − (1 − MR fraction)(1 − AR fraction), bounded to prevent unbounded recirculation. MR is further influenced by modeled LV systolic pressure and prolapse; AR by heart rate and selected unloading response.
Acute regurgitation can raise filling pressure without assuming chronic dilation. AR removes truly isovolumic contraction and relaxation. Generic MR permits systolic/relaxation leakage; the selected late-systolic MVP phenotype initially closes and then prolapses. RV loops apply analogous TR/PR accounting.
Dynamic prolapse and obstruction
MVP responds to transmural loading, afterload and contractility: smaller filling or reduced afterload can worsen the selected prolapse phenotype; reduced inotropy can lessen it. HOCM uses a separate dynamic outflow factor. Similar maneuver directions do not mean that MVP and HOCM are the same disease.
Post-treatment pressures and regurgitant modifiers are shared with atrial waves, echo volume, PV and formula readouts. A treatment is not applied again inside the volume drawing.
References & further reading