Catheter estimation of
stenotic valves
Dr. DAYASAGAR RAO
KIMS
HYDERABAD
Stenotic valve orifice areaevaluation
• Cardiac catheterization- gold standard?
• Echo doppler
• MRI based
• MDCT
Clinical
Stenotic valve orifice areaevaluation
• Is there role of catheter based
assessment- stenotic valves in 2009?
ACC/AHA guidelines valvular heart
disease-evaluation 2008
• Discrepancy:
clinical findings
noninvasive data
.
• Technically unsatisfactory non invasive
data (echo-doppler)
operator dependent
acoustic window
TEE
• Low flow- low gradient: aortic stenosis
Catheter based – evaluation of
stenotic orifice
• Is it safe?
tight/ critical stenosis
cerebral embolism- calcific aortic stenosis
Omran et al:
LANCET 2003
152 patients aortic stenosis
randomized: CAG only
Vs
CAG + crossing of aortic valve (retrograde)
Stenotic orifice area (catheter
based)
• Brain MRI: diffusion imaging
22% focal diffusion imaging abnormalities
3% clinically apparent neurodeficit
only in patients- crossing of aortic valve.
Stenotic orifice area- catheter
based
• Aortic stenosis:
retrograde approach
antegrade
Mitral stenosis:
LV- PCW
LV- LA
Stenotic orifice area
AORTIC STENOSIS- (LV-AO)
METHOD
EASE OF USE
DISADVANTAGE
PULLBACK
+++++
LEAST ACCURATE
FEMORAL SHEATH
+++++
PRESSURE
AMPLIFICATION ILIAC
ARTERY STENOSIS
DOUBLE ARTERIAL
PUNCTURE
+++
EXTRA VASCULAR
ACCESS RISK
PIG TAIL- DOUBLE
LUMEN
+++
DAMPING
PIG TAIL + PRESSURE
+++
EXPENSE
TRANSEPTAL
++
RISK
STENOTIC ORIFICE AREA
• MITRAL STENOSIS
• LV-PCW
• LV-LA TRANSEPTAL
• PROPER PCW PRESSURE: MEAN WEDGE- MEAN
PA
• ALIGNMENT MISMATCH- TIME DELAY 50-70
msec
• REALIGNMENT- PEAK OF V WAVE BISECTED BY
LV PRESSURE DOWNSTROKE.
STENOTIC ORIFICE AREA
MILD
MODERATE
SEVERE
AORTIC
>1.5 sq cm
1-1.5 sq cm
<1 sq cm
MITRAL
>1.5 sq cm
1-1.5 sq cm
<1 sq cm
TRICUSPID
<1 sq cm
PULMONARY
Peak gradient
>60 mm hg
VALVULAR STENOSISSEVERITY
• Valvular disease cause of symptoms
• Timing of intervention: symptomatic
status
natural history- symptoms
Stenotic orifice area
• Geometric orifice area
• Effective orifice area
• Critical valve area
DIAGRAM SHOWING
• Geometric / effective orifice area
• Contraction co efficient
Contraction coefficient
STENOTIC ORIFICE- VALVES
• Hemodynamic impact influenced by
• Cross sectional area
• Geometry of valve – flat valves have
greater contraction co-efficient (for similar
CSA and volume flow)
Stenotic orifice area
• Clinical implication:
- Planimetry area
- Effective orifice area (continuity/Gorlins)
- EOA smaller than planimetered areaproportional contraction coefficient.
PRESSURE RECOVERY
• Fluid energy= pressure energy+ kinetic
energy
• Narrowed orifice (vena contracta) highest
velocity
• Downstream - flow stream expands
• Deccleration (decreased velocity- kinetic)
• Conversionkinetic – pressure
(pressure recovery)
PRESSURE RECOVERY
Clinical implication- pressure
recovery
• Doppler derived gradients- using CW
doppler @ vena contracta
• Catheter derived gradients- downstream
vena contracta- pressure recovery
GRADIENT DERIVED BY CATH IS LOWER
THAN DOPPLER DERIVED GRADIENT
PROSTHETIC VALVES
Bileaflet valves
• Side orifice velocities are less than central
orifice velocities. (side orifice velocities is 85%
of central orifice)
• Pressure recovery occurs much further
downstream in central orifice than side orifice.
• Discrepancy measurement of gradients- over
time.
Stenotic orifice area- pressure recovery
• Pressure recovery is more across aortic
than at mitral
prosthetic valve- native valve.
• Pressure recovery- exaggerated in
- Smaller aorta
- Stiffer aorta
- Hypertension
• Discrepancy between catheter derived and doppler
derived pressure data. (thus calculated valve area)
Stenotic orifice area- pressure recovery
(exaggeration- HTN)
Stenotic valve area
Torricelli’s law
• F= A X V
A=F/V
A=F/V Cc
F- Flow
A- Valve area
V- Velocity of flow
Cc- coefficient of contraction
Stenotic valve area
• V2 = (CV)2 X 2Gh
• V= (CV) x sq root 2Gh
h = pressure gradient
G = gravitational constant (980 cm/sec2)
for conversion cmH2 to units pressure
Cv- coefficient velocity for correcting energy
loss
(pressure energy- kinetic energy)
Stenotic valve area
• A= F/V
F- flow (vol flow ml/sec)
• Flow rate= cardiac output/ duration of
systole or diastole (SEP/DFP X HR)
Stenotic valve area
• Valve area= cardiac output ÷ (HR X SEP)
44.3 X C X sq root of pressure
gradient
C- empirical constant
calculated valve area (by Gorlin)
actual valve area (at surgery)
Mitral Valve = constant 0.7 (later changed 0.85)
Aortic valve: assumed to be 1
GORLINS FORMULA
•
•
•
•
•
(AHJ 1951 Gorlin R, Gorlin G)
Eleven patients
Right heart catheterization- PCWP
Assumed LV diastolic pressure- 5mmhg
Duration diastole- peripheral arterial
tracing
• Calculated mitral valve area
• Measured MVA at surgery
GORLIN FORMULA
• Cardiac output
• Pressure gradient across valve
(mitral/aortic)
• Duration of flow (DFP/SEP)- pressure
tracing
• Constant (calculated-measured valve
area)
GORLIN FORMULA
Empirical constant includes
Conversion of cms H2o to units of pressure
• Contraction co-efficient
• Velocity co-efficient
• Difference-
valve area calculatedand valve area at surgery
GORLIN FORMULA
Problems
• cardiac output
Fick - oxygen consumption
Thermodilution- low output state
- significant TR
• Duration of flow (SEP-DFP)
• Alignment mismatch
• Calibration errors
GORLIN FORMULA
• Modification: HAKKI
cardiac output (L/ min)
Sq root of MPG
• Heart rate: 60- 100/ min
Stenotic valve orifie area
• Catheterization : gold standard ?
(Grossman et al 2006)
1.Invasive procedure
2.Risk
3.Limitations – measured parameters
- calibration
-valvular regurgitation
4.Expensive
ACC/AHA Guidelines