Valvular Heart Disease

VALVULAR HEART DISEASE (VHD)

• Either acquired or congenital
• Incidence decreased due to advanced technology
• Laminar flow is smooth and its peak velocity is within the center of the flow. When normal valve is open, pressure on either side of the valve is equal w/no sig. pressure gradient (PG).
• FLOW = FLOW = FLOW think of a hose and any disruption in the flow
• Stenotic valve (obstruction) and/or regurgitant (leaky) valve create chaos.
• Stenotic valve leads to pressure overload, turbulent floaw, and hypertrophy. Creates turbulent, high velocity jets. 
• Regurgitant valve leads to volume overload, turbulent flow, and dilation. Creates turbulent, high velocity jets. 
• Diagnostics: 2D echo, CFD, CWD/PEDOF. 
• Waves:
  • TS/MS & TR/MR: jet travels toward the transducer during diastole (normal TV/MV flow); it’s narrow and turbulent with increased velocity
  • TR/MR jet is turbulent and travels away from the transducer during systole, when valve is closed.
  • TS/MS & TR/MR: Doppler waveform travels toward the transducer (above the baseline) during diastole (normal TV/MV flow) w/increased velocity & flatter waveform.
  • TR/MR Doppler waveform travels away from the transducer (below the baseline) during systole
  • AR jet is turbulent and travels toward the transducer during diastole. 
  • AS jet travels away from the transducer during systole (line normal AOV flow); it’s narrow and turbulent w/increased velocity.
  • PR jet is turbulent and travels toward the transd. During diastole. 
  • PS jet travels away from the transd. During systole, it is narrow and turbulent w/incr velocity
  • AR/PR Doppler waveform travels toward the trands. During diastole
  • AS/PS Doppler waveform travels away from the transducer – below the baseline, during systole, w/incr. vel.

VALVULAR STENOSIS

• Is the narrowing, thickening, fusion, or blockage of valve that obstructs blood flow through the valve; 3 levels: proximal (before valve), at the level of the stenosis (at the valve) and distal (after the valve).
  • Proximal: blood backs up, pressure increases: stenotic valve obstructs the flow. Pressure goes up, creates pressure overload pattern (increased afterload). Hypertrophy (thickening of walls). The greater the demand on muscle, the more it thickens and grows.
  • Severe stenosis -> greater backup, greater pressure, severe hypertrophy.
  • At the level: DOMING – when leaflets “round inwards” and don’t close fully. Increased pressure pushes on the undersurface of the tethered leaflets to cause doming. Thickening/fusion/calcification of the valve leaflets decreases the valve area within its orifice. 
  • Distal to the stenotic valve: turbulent flow, pressure decreases. (CFD more often). Mosaic pattern Doppler – red blood cells are traveling in multiple directions. Severe stenosis -> smaller area, greater velocity, more turbulent flow. REMEMBER: the atrium or ventricle has to squeeze harder to get the blood out. Decreased flow distal to the stenosis decreases the distal pressure. PG generated by the stenosis <36mmHG mild, 36-64mmHG moderate, >64 mmHg Severe. 
• TTE w/Doppler
  • ATRIOVENTRICULAR VALVES: MS and TS
    • Pressure Half Time P1/2t- time required for the peak gradient across the valve to reduce to one-half:
    • Mitral valve: MVA (cm2) = 220/PHT
      • Continuity equation: SVlvot = SVmv

LVOTarea = pi x (LVOTdiameter / 2)to the 2 power

MVA (cm2) = LVOT area x LVOT VTI / MV VTI 

PISA flow rate= 2 pi r2 * Va

MVA = (PISA flow rate / Vmax) x (angle funnel/180)

    Tricuspid Stenosis:   

        Mean Gradient Pressure >= 5mmHg

        Pressure Half Time >= 180ms

        Inflow VTI >60cm

        Valve Area by Continuity Equation* <= 1cm2

• SEMILUNAR VALVES: AS & PS
  • Peak velocity
  • Aortic valve and pulmonic valve area via the continuity equation: 
    • AVarea = LVOTarea x LVOT VTI / AV VTI
    • AVarea = [pi * (LVOTdiameter/2)2 x LVOT VTI ] / (AV VTI)

• VALVULAR REGURGITATION:
  • Insufficiency – valve doesn’t close completely
    • Primary: degeneration, inflammation, infection, trauma –structural changes of a valve
    • Secondary: chamber remodeling eg. Enlarged ventricle
      • Analogy of a door in a frame: door is the primary, frame is secondary
• Doppler assessment
• In chronic insufficiency: volume overload pattern (increased preload) results in extra blood dumped into the proximal chamber. Chamber dilation.

Works Cited

Otto, Catherine: Textbook of Clinical Echocardiography

DeWitt, Suzanne: Echocardiography from a Sonographer’s Prespective: The Workbook

Both textbooks are highly recommended