Valvular Pathology



Figure 5.1
Calcified tricuspid aortic valve stenosis seen in long axis (left) and short axis (right); note significant leaflet calcification restriction of motion (arrows). LA left atrium, LV left ventricle, RV right ventricle, Ao aorta, RA right atrium




 


2.

Calcific stenosis of congenitally abnormal valve – review of 932 excised aortic valves (in patients without concomitant mitral valve replacement or mitral stenosis) showed that 59 % of men and 46 % of women had bicuspid or unicuspid aortic valve [1]



  • Unicuspid aortic valve



    • Anatomy: One leaflet; acommissural (no commissure) or unicommissural-one commissure (Fig. 5.2a)

      A322490_1_En_5_Fig2_HTML.jpg


      Figure 5.2
      (a) Shows unicupsid aortic valve. (b) Shows bicuspid aortic valve with fusion of the right and left leaflets


    • Rare form of congenital aortic stenosis (0.02 % incidence)


  • Bicuspid aortic valve (Fig. 5.2b)



    • Anatomy: two leaflets and two commissures from cusp fusion of right and left – 86 %, cusp fusion of right and non-coronary – 12 %, left and non-coronary – 3 % [2]


    • Associated lesions: coarctation of aorta, dilatation of aortic root, ascending aorta, sinus of Valsalva aneurysm, sub and supra valvular aortic stenosis, Shone’s complex, Turners Syndrome, ventricular septal defect [3, 4].

 

3.

Rheumatic heart disease

Important etiology of aortic stenosis in developing countries

 



N.B. up to 80 % of patients with AS will also have AR

Interesting fact: First description and sketches of bicuspid aortic valve are attributed to Leonardo da Vinci [5]



Evaluation of Aortic Valve






  • Morphology of the valve


  • Aortic Stenosis velocity by continuous wave Doppler (note, the recorded velocity is at effective orifice area, not anatomic area) [6]. N.B. Measure maximal velocity at outer edge of dark signal


  • Mean and maximal transaortic gradient (do not forget that ΔP = 4 (V2max−V2proximal) for cases when proximal velocity is >1.5 m/s or aortic velocity is <1.5 m/s)


  • LVOT diameter – measure in mid systole (N.B. in many patients LVOT is elliptical and not circular leading to underestimation of AVA)


  • LVOT velocity by pulsed Doppler


  • N.B. pressure recovery has to be taken into account for aortic size <30 mm (pressure drop across the stenosis will be overestimated)



$$ \mathrm{A}\mathrm{V}\mathrm{A}={\mathrm{AREA}}_{\mathrm{LVOT}}\cdot {\mathrm{VTI}}_{\mathrm{LVOT}}/{\mathrm{VTI}}_{\mathrm{AV}}=\pi /4\;{\mathrm{D}}^2\cdot {\mathrm{VTI}}_{\mathrm{LVOT}}/{\mathrm{VTI}}_{\mathrm{AV}} $$




Aortic stenosis severity [7, 8]






































 
Mild
Moderate
Severe

AVA (cm2)
>1.5
1.0–1.5
≤1

AVA index

(cm2 /m2)
    
≤0.6

Mean Gradient

(mm Hg)
<20
20–39
≥40

Aortic Jet Velocity (m/s)
2.0–2.9
3.0–3.9
≥4

Velocity Ratio

(LVOT/AV)
>0.5
0.25–0.5
<0.25


Note: V < 2.5 m/s with normal cardiac output – aortic sclerosis

Low Flow Low Gradient Aortic Stenosis with decreased Ejection Fraction (present in 5–10 % of Severe AS patients) [9, 10]



  • LVEF < 40 %


  • Mean pressure gradient <30–40 mmHg


  • Effective orifice area <1.0 cm2

Possible situations: severe AS causing LV dysfunction limiting the ability to generate high transaortic valve gradients or patient with moderate AS and LV dysfunction from other etiology.

Dobutamine stress test:



  • Get images at rest, 2.5–5 μg/kg/min, 10 μg/kg/min, 20 μg/kg/min (increase dose every 3–5 min)


  • Record: LVOT diameter (at rest), AV VTI, LVOT VTI, AV mean pressure gradient, Aortic valve Vmax, Heart Rate


  • Stop when positive result is obtained or heart rate goes over 20 bpm over the baseline or exceeds 100 bpm, blood pressure drops, or when there are appearances of arrhythmias or symptoms.


  • Useful formulas:






    • $$ \mathrm{A}\mathrm{V}\mathrm{A}=\pi /4\;{{\mathrm{D}}^2}_{\mathrm{LVOT}}\cdot {\mathrm{VTI}}_{\mathrm{LVOT}}/{\mathrm{VTI}}_{\mathrm{AV}} $$





    • $$ \mathrm{S}\mathrm{V}=\pi /4\;{{\mathrm{D}}^2}_{\mathrm{LVOT}}\cdot {\mathrm{VTI}}_{\mathrm{LVOT}} $$





    • $$ \mathrm{C}\mathrm{O}=\pi /4\;{{\mathrm{D}}^2}_{\mathrm{LVOT}}\cdot {\mathrm{VTI}}_{\mathrm{LVOT}}\;\mathrm{H}\mathrm{R} $$




  • Result interpretation [7]

    (a)

    Vmax >4 m/s or mean pressure gradient >40 mmHg (assuming AVA <1 cm2) – severe stenosis

     

    (b)

    AVA >1 cm2 – stenosis is not severe

     

    (c)

    Evaluate contractile reserve (increase of stroke volume or cardiac output by >20 %). Note – does not predict improvement of EF, but predicts mortality [11, 12].

     



Aortic Regurgitation



Etiology




Aortic Root Dilatation (Secondary)



  • Marfan’s syndrome


  • Idiopathic aortic dilation


  • Cystic medial necrosis


  • Senile aortic ectasia and dilation


  • Syphilitic aortitis


  • Giant cell arteritis


  • Takayasu’s arteritis


  • Ankylosing spondylitis


Valvular Abnormalities (Primary)



  • Rheumatic fever


  • Infective endocarditis


  • Collagen vascular diseases


  • Degenerative aortic valve disease


  • Bicuspid Aortic Valve


  • Unicuspid Aortic Valve


  • Quadricuspid Aortic Valve (Fig. 5.3)

    A322490_1_En_5_Fig3_HTML.jpg


    Figure 5.3
    Quadricuspid aortic valve; all four leaflets best seen when valve is closed forming a characteristic cross sign


Evaluation






  • Aortic valve morphology


  • Aortic Root Morphology


  • Left Ventricle (dimensions and performance)


  • Aortic Flow


  • Left ventricular size and function


  • Flow in the aorta


Useful Formulas



  • Deceleration time:






    • $$ DT=0.29\;PHT $$


  • Regurgitant Volume






    • $$ RV= EROA\cdot VT{I}_{AR} $$





    • $$ RV=p/4\;{\left( LVOT\;D\right)}^2\cdot VT{I}_{Ao}-p/4\;{\left(MV\;D\right)}^2\cdot VT{I}_{MV} $$





    • $$ RV= Stroke\;V-p/4\;{\left(MV\;D\right)}^2\cdot VT{I}_{MV} $$


  • Regurgitant Fraction






    • $$ RF=RV/SV=RV/\;\left(p/4\;{\left( LVOT\;D\right)}^2\cdot VT{I}_{Ao}\right) $$


  • EROA






    • $$ EROA=RV/\;VT{I}_{AR};\; EROA=2p{r}^2{u}_{aliasing}/\;{u}_{AR} $$




Chronic aortic regurgitation evaluation [8, 13]









































































 
Mild
Moderate
Severe

Regurgitant Jet/LVOT Diameter
<0.25
0.25–0.45 mild-moderate

0.46–0.64 mod-severe
>0.65

Regurgitant Jet Area/LVOT Area (cross sectional area)
<0.05
0.05–0.2 mild-moderate

0.21–0.59 moderate to severe
≥0.6

Regurgitant Volume (ml)
<30
30–44 mild-moderate

45–59 moderate to severe
≥60

Regurgitant fraction
<30 %
30–39 mild-moderate

40–49 moderate to severe
≥50 %

EROA (cm2)
<0.1
0.1–0.19 mild-moderate

0.2–0.29 mod-severe
≥0.3

Vena Contracta (cm)
<0.3
0.3–0.6
>0.6

Pressure Half-time (ms) (=0.29DT)
>500
  
<200

Decceleration rate (m/s2)
<2
  
>3.5

MV flow pattern
    
restrictive

Aortic Doppler
Mild early diastolic reversal in descending aorta
  
Holodiastolic flow reversal in descending aorta

Doppler
Faint continuous Doppler sign
  
Dense continuous Doppler sign

LVEDD (mm)
<55
  
>75



Mitral Valve Lesions


Mitral valve has such a name due to its resemblance to a mitre, a bishop’s headgear [14].


Mitral Stenosis



Etiology






  • Rheumatic Heart Disease (vast majority of cases)


  • Congenital mitral stenosis


  • Severe calcification of mitral annulus


  • Systemic lupus erythematosus (rare)


  • Fabry’s disease (rare)


Evaluation






  • Mitral valve morphology


  • Left Atrial size


  • Pulmonary Pressures


Rheumatic Mitral Stenosis (Fig. 5.4, Videos 5.5 and 5.6)




A322490_1_En_5_Fig4_HTML.jpg


Figure 5.4
Parasternal long (left) and short axis (right) views showing rheumatic mitral stenosis. Note the hockey-stick appearance of the anterior leaflet (left image) consistent with rheumatic etiology of stenosis. Parasternal short axis view shows commissural fusion and “fish mouth” opening in rheumatic mitral stenosis. LA left atrium, LV left ventricle, RV right ventricle
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Jul 10, 2016 | Posted by in CARDIOLOGY | Comments Off on Valvular Pathology

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