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← Section II · Valvular Heart Disease
II.E

Fluid Dynamics of Regurgitant Jets

10 cards

Notes

Three regions of a regurgitant jet

  1. Proximal flow convergence - hemispheric surface of iso-velocity (PISA). Used for EROA calculation.
  2. Vena contracta - the narrowest, highest-velocity segment just downstream of the orifice; approximates the effective orifice diameter. Grade with color VC width.
  3. Distal jet - turbulent expansion into the receiving chamber.

PISA-based EROA calculation

EROA=2πr2×ValiasingVpeak regurg\mathrm{EROA} = \frac{2\pi r^2 \times V_{aliasing}}{V_{peak\,regurg}}

  • Baseline-shift the color scale in the direction of the jet to lower the aliasing velocity to ~30–40 cm/s → obtain optimal hemispheric PISA.
  • Zoom the ROI; measure r from aliasing edge to orifice.
  • Regurg volume = EROA × VTI_regurg jet.

Vena contracta

  • Best measured with narrow color sector, zoomed image, high frame rate.
  • Aortic VC: severe if > 0.6 cm.
  • Mitral VC: severe if ≥ 0.7 cm.
  • Tricuspid VC: severe if ≥ 0.7 cm.

Volumetric (SV-difference) method

  • Regurg volume = SV_regurg valve − SV_reference valve (where reference has no significant regurgitation).
  • MR: SV_mitral − SV_LVOT.
  • AR: SV_LVOT − SV_mitral.

Effect of jet direction and Coanda effect

  • Eccentric wall-hugging (Coanda) jets appear smaller by color area but are usually more severe than a central jet of the same appearance.
  • Color area method underestimates severity in wall-hugging jets.
  • Use PISA/VC/volumetric quantitation instead.

Nyquist limit for jet analysis

  • Color scale Nyquist for jet-area methods ≈ 50–70 cm/s.
  • Lowered to 30–40 cm/s specifically for PISA hemisphere.
  • Changing Nyquist changes the visual area of the jet (higher Nyquist → smaller jet area).

Downstream flow-pattern effects

  • Severe MR → systolic pulmonary vein flow reversal.
  • Severe TR → systolic hepatic vein flow reversal.
  • Severe AR → holodiastolic aortic flow reversal (proximal descending aorta).
  • Severe PR → holodiastolic pulmonary artery flow reversal (below the pulmonic valve).

Pressure gradient across a regurgitant jet

  • Peak regurgitant velocity reflects the instantaneous chamber-to-chamber pressure difference (via ΔP = 4v²).
  • AR CW peak velocity = √((DBP_ao − LVEDP)/4) in principle; a low peak velocity means a small aorta-to-LV pressure difference (i.e., acute severe AR).
  • MR peak velocity ~5–6 m/s in a hypertensive LV vs 3–4 m/s in a severely regurgitant, hypotensive LV.

Cards

  • basicII.E-001
    Name the three regions of a regurgitant jet used in quantitation.
    → Proximal flow convergence (PISA), vena contracta (narrowest segment), and the distal turbulent jet.
  • basicII.E-002
    State the PISA formula for EROA.
    → EROA = (2π r² × V_aliasing) / V_peak regurg. Regurg volume = EROA × VTI_regurg.
  • basicII.E-003
    What color-Doppler adjustment optimizes PISA hemisphere formation?
    → Shift the color baseline in the direction of the jet to reduce aliasing velocity to ~30–40 cm/s. This enlarges the PISA hemisphere and improves the accuracy of the radius measurement.
  • basicII.E-004
    State the severe vena contracta widths for AR, MR, and TR.
    → Severe AR: VC > 0.6 cm. Severe MR: VC ≥ 0.7 cm. Severe TR: VC ≥ 0.7 cm.
  • basicII.E-005
    How is the color-area (% of receiving chamber) method affected by an eccentric wall-hugging jet?
    → It UNDERESTIMATES severity — the Coanda effect makes wall-hugging jets appear smaller than they truly are. Use PISA, VC, or volumetric methods for accurate grading.
  • basicII.E-006
    Downstream flow pattern in severe MR vs severe AR — where do you look?
    → Severe MR: SYSTOLIC pulmonary vein flow reversal. Severe AR: HOLODIASTOLIC flow reversal in the proximal descending / abdominal aorta.
  • basicII.E-007
    Downstream flow pattern for severe TR? Severe PR?
    → Severe TR: systolic hepatic vein flow reversal. Severe PR: holodiastolic pulmonary artery flow reversal (below the pulmonic valve).
  • basicII.E-008
    State the volumetric method for calculating MR volume.
    → RV_MR = SV_mitral − SV_LVOT, where SV_mitral = CSA_MV annulus × VTI_MV inflow and SV_LVOT = CSA_LVOT × VTI_LVOT. Only valid when the aortic valve is competent.
  • basicII.E-009
    What is the acceptable color Nyquist range for JET-AREA analysis vs PISA?
    → Jet-area/color surveys: Nyquist ~50–70 cm/s. For PISA hemisphere: baseline-shifted Nyquist ~30–40 cm/s.
  • basicII.E-010
    Why can a LOW peak velocity of an AR CW jet actually indicate severe (acute) AR?
    → Peak AR velocity reflects (aortic DBP − LVEDP). In acute severe AR, LVEDP rises rapidly while aortic DBP falls, so the gradient — and thus peak velocity — is small (rapid pressure equalization). Also produces steep deceleration / short PHT.