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Valvular Abnormalities and Disease


Primary vs. Secondary Findings:
A primary finding refers to the primary cause of the abnormality EX: atherosclerosis formation on the aortic valve causes the stenosis
A secondary finding refers to other abnormalities caused by the primary abnormality EX: aortic stenosis causes thickening of the LV wall and post-stenotic dilatation of the aortic root

Four Considerations When Evaluating Cardiac Valves:
  1. How many valve leaflets are present?
  2. Do you see abnormal masses, thickening or calcification attached to the valve leaflets?
  3. Is leaflet mobility normal, restricted or hypermobile?
  4. What are the associated abnormalities of the cardiac chambers and other cardiac valves?
AORTIC VALVE ABNORMALITIES

Aortic Stenosis - Atherosclerosis:

  • Varying degrees of leaflet thickening will be demonstrated
  • Fusion of the edges of the leaflets may occur with severe stenosis
  • Hypertrophy of the muscle wall of the ventricle will occur as it adapts to the chronic pressure overload
Clinical Symptoms:
  • Dyspnea/Shortness of breath most common symptom
  • Orthopnea
  • Palpitations
  • Fatigue
  • Dizziness and syncope due to decreased cardiac output
  • Harsh systolic crescendo-decrescendo murmur best heard at the right upper sternal border
  • Systolic ejection click
M-mode:
  • Used to assess systolic leaflet separation
  • <12 mm cusp separation indicates significant obstruction
  • Method is not very accurate in determining the severity of the stenosis
  • Thickened leaflets cause multiple echoes to be displayed in diastole
  • Decreased leaflet separation and multiple echoes filling the space between the aortic root and AV opening
  • LVH due to pressure overload
  • Post stenotic aortic root dilatation due to eccentric flow through stenosis
2D and Doppler Evaluation:
  • PLAX - delineates the restricted opening of the tips of the aortic leaflets
  • PSAX - at the level of the aortic valve demonstrates the true orifice of the stenotic valve ; area can be traced, ****planimetry is not very accurate because heavily calcified leaflets cause bright echoes with poorly defined borders making measurement difficult
  • AP 5/AP 3 – Doppler evaluation of the LVOT and AV velocities
  • Pedoff probe applied at the apical, right parasternal and suprasternal windows
  • Average normal aortic valve area is 3cm2
  • Average PSV 1.4m/s
  • Increasing velocities and acceleration times are noted with increasing severity of stenosis
  • Aortic flow may be recorded from the apical, suprasternal or parasternal locations
  • Velocity and PPG alone cannot diagnose stenosis due to variations in cardiac output, you must know the valve area
  • Heavy calcification on the leaflets can lead to understimation of  stenosis due to degraded Doppler signal and inability to locate the highest velocity
ASE Classifications:
  • Aortic sclerosis <2.5m/s
  • Mild:                PSV 2.6 – 3m/s;        PPG <36mmHg
  • Moderate:       PSV 3 – 4m/s;           PPG 36 – 64mmHg
  • Severe:            PSV >4m/s;               PPG >64mmHg
  • Valve area calculated by continuity equation (independent of cardiac output, NOT affected by regurge):
       >        Mild:  1.5 – 2.0cm2
       >        Moderate:  1.0 - 1.5 cm2
       >        Severe:  <1.0 cm2
  • Dimensionless Orifice Index, VTI 1 / VTI 2 ratio (independent of cardiac output);  Severe stenosis at <0.25
Peak Pressure Gradient (PPG):
  • Mild (normal or increased cardiac output) <36 mmHg
  • Moderate 37-64 mmHg
  • Severe (normal or depressed cardiac output) >64 mmHg
  • PPG is not an accurate method of assessing AS in patients with severe AI; LV becomes hypercontractile due to the continuous reprocessing of the same blood; PPG will be higher than the actual gradient related to the stenotic valve
Mean Pressure Gradient (MPG):
  • Mild (normal or increased cardiac output) <20mmHg
  • Moderate 21-40mmHg
  • Severe (normal or depressed cardiac output) >40 mmHg
  • Critical >50 mmHg
  • MPG can be used to assess aortic stenosis in patients who also have aortic insufficiency
  • MPG calculated on Doppler best correlates with the mean pressure gradient obtained during heart cath
Associated Abnormalities:
  • LVH with left heart pressure overload
  • Dilated aortic root
  • Turbulence distal to the valve
  • Can be associated with CVA/Stroke due to decreased flow to brain and embolus potential from atherosclerotic disease on cusps

Rheumatic Heart Disease:
  • Valvular degeneration and thickening from rheumatic heart disease usually affects BOTH the AV and MV where atherosclerotic disease usually affects one valve or the other
  • May cause MS/MR and/or AS/AI
  • Leads to same 2D/Doppler appearance as atherosclerotic stenosis

Congenital Aortic Valve Stenosis:
  • Usually involves an abnormal leaflet number with restricted movement
  • Can be unicuspid, bicuspid or quadricuspid
  • Some bicuspid valves are composed of 3 leaflets with 2 fused together causing decreased AVA/stenosis
AV Regurgitation/Insufficiency:

Acute AV Regurgitation:
  • Can be considered a critical finding with severe regurgitation
  • Left ventricular pressure rises rapidly and can cause premature closure of the mitral valve and early opening of the aortic valve
  • Left ventricle dimension is usually NORMAL with the acute onset of the regurgitation
  • Restrictive filling pattern demonstrated by E/A > 1.5 and short deceleration time
Symptoms:
  • Chest pain
  • Orthopnea - difficulty breathing when supine
  • Cough
Common Causes:
  • Infective endocarditis
  • Aortic dissection of the ascending aorta
  • Trauma
Chronic AV Regurgitation:

Symptoms:
  • Heart Failure
  • Chest Pain
  • Fatigue
  • Dyspnea/Orthopnea
  • High pitched, early diastolic decrescendo murmur heard along the left sternal border; severity of the murmur is inversely proportional to the duration of the regurgitation
  • Austin Flint murmur - severe AI; low frequency diastolic murmur
Common Causes:
  • Inadequate leaflet coaptation
  • Ruptured leaflet or vegetation
  • Dilatation of the valve annulus
  • Bacterial endocarditis
  • Fibrosis/Calcification of the leaflets
  • Rheumatic heart disease
  • Chronic volume overload of the left ventricle may cause dilatation
  • Aortic valve is more resistent to regurgitation than the mitral valve due to structural differences in the valve
  • Aortic valve is the most resistent to regurgitation when compared to all of the heart valves
Treatment:
  • Valve replacement indicated when the left ventricle is significantly enlarged and fractional shortening of the ventricle is reduced
  • End diastolic dimension >5.5cm and FS% <25%
2D/M-Mode:
  • Flow starts before the mitral valve opens and continues until shortly after it closes
  • Best recorded with a transducer in apical position or from a suprasternal location
  • Fluttering of the anterior leaflet of MV or IVS in diastole
  • May see premature closure of the MV and reverse doming of the MV in diastole
  • Chronic AI leads to LV volume overload and hypercontractile LV motion
  • LA dilatation occurs with significant chronic aortic insufficiency
  • Significant AI can cause early closure of the MV in diastole due to increased diastolic pressures in the LV
  • Mild: Little to no effect
  • Moderate/Severe:  LV dilatation and hypercontractility, mild LA enlargement
  • Early MV closure seen on m-mode with severe AI
  • May cause IVS fluttering and anterior MV leaflet vibration in diastole due to eccentric jet
Color Doppler:
If the regurgitation jet fills LVOT at a ratio:
  • <30% suggests mild regurgitation
  • 30% to 60% suggests moderate regurgitation
  • >60% suggests severe regurgitation 
  • Vena contracta <0.3cm is mild; >0.6cm is severe
  • Vena contracta width can be performed at the narrowest segment of the regurgitant jet between proximal flow convergence and distal jet expansion
PW/CW Doppler:
  • The denser the jet appearance on the Doppler display, the more severe the regurgitation
  • Peak velocity of the regurgitation indicates the maximum pressure gradient between the aorta and the LV in diastole, not helpful in diagnosing severity of the regurgitation; 70mmHg = about 4m/s peak velocity in the normal heart
  • Pressure half-time of the slope of the Doppler tracing used to assess severity of regurgitation
  • SSN notch used to assess flow reversal in the descending aorta
  • Pressure half-time: time it takes for the pressure gradient to reduce by 1/2
       >        shorter time = more severe AI
       >        Mild >500 msec
       >        Moderate 200-500 msec
       >        Severe <200 msec
  • Moderate : early diastolic flow reversal in descending aorta
  • Severe: flow reversal throughout diastole in the descending aorta; causes overestimation of the peak pressure gradient through a stenotic AV due to the hypercontractile motion of the LV
  • The waveform of mitral stenosis and aortic regurgitation can be difficult to distinguish on the Doppler tracing; if the flow pattern begins before the mitral valve opens, the waveform is from aortic regurgitation

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