Catheter estimation of stenotic valves

Dr. DAYASAGAR RAO

KIMS

HYDERABAD

Stenotic valve orifice area-evaluation

• Cardiac catheterization- gold standard?

• Echo doppler

• MRI based Clinical

• MDCT

• Is there role of catheter based assessment- stenotic valves in 2009?

Stenotic valve orifice area-evaluation

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 areaAORTIC 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 STENOSIS- SEVERITY

• 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 area- proportional contraction coefficient.

PRESSURE RECOVERY

• Fluid energy= pressure energy+ kinetic energy

• Narrowed orifice (vena contracta) highest velocity

• Downstream - flow stream expands

• Deccleration (decreased velocity- kinetic)

• Conversion- kinetic – 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 calculated-

and 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 procedure2.Risk 3.Limitations – measured parameters - calibration -valvular regurgitation4.Expensive

ACC/AHA Guidelines