hemo dynamics
Post on 22-Dec-2015
6 Views
Preview:
DESCRIPTION
TRANSCRIPT
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
top related