1. Principles of haemodynamic measurements: Pressure and flow measurements calculation of cardiac output Calculation of shunts valve area
DEEPAK NANDAN

2. Definition of Hemodynamics
Hemodynamics is concerned with the physical and physiological principles governing the movement of blood through the circulatory system.
The forces involved with the movement of blood throughout the human circulatory system include:
1. Kinetic and potential energy provided by the cardiac pump
2. Gravity
3. Hydrostatic Pressure
4. Pressure gradients, or differences, between two any points

3. Properties of blood itself that affect its flow:
1. Viscosity
2. Inertial mass
3. Volume of blood to be moved
Factors that affect the motion of blood through the vascular conduits include:
1. Size of blood vessel
2. Condition of blood vessel
3. Smoothness of lumen
4. Elasticity of muscular layer (tunica media)
5. Destination of blood (distal vascular bed)

4. Definition of Physical Concepts
PRESSURE: the ratio of a force acting on a surface to the area of the surface
(force per unit area).
Units : Newtons/m², pascal (Pa), atmospheres(atm), mmHg.
FLOW RATE: Amount of fluid passing a given point over a given period of time
Described as either flow volume or flow velocity.
Flow volume is measured in mI/mm or cm3/sec - defined by Poiseuille’s
law.
Flow velocity is measured in cm/sec or m/sec - described by Bernoulli’s principle.
VISCOSITY: The internal friction between adjacent layers of fluid.
Blood is 1.5 times as viscous as water and its viscosity is directly related to hct level

5. KINETIC ENERGY: active energy , the energy of motion.
In hemodynamics- described as the forward movement of blood.
POTENTIAL ENERGY: stored energy.
Kinetic energy is transferred into potential energy when it produces a lateral pressure or stretching of vessel walls during systole.
The potential energy is converted back into kinetic energy when the arterial walls rebound during diastole.

8. Energy in the blood stream exists in three interchangeable forms:
Energy in the blood stream exists in three interchangeable forms: 1)pressure arising from cardiac output and vascular resistance, 2)hydrostatic pressure from gravitational forces,
3)kinetic energy of blood flow
TE = (perpendicular pressure + gravitational pressure) + kinetic energy
TE = (P per + P grav) + ½ ρ V²
BP—lateral pressure, kinetic energy (also known as the impact pressure or the pressure required to cause flow to stop), and gravitational forces.
Kinetic energy- highest in aorta (< 5% contribution)
Gravitational forces - important in a standing person, minimal impact while supine
The intravascular pressure is responsible for transmural pressure(i.e. vessel distention) and for longitudinal transport of blood.

10. Pressure ΔP = ρg Δh PRESSURE IN STATIC FLUIDS
Rest- the pressure caused by liquid is α to the depth of the liquid & density
pressure is exerted equally in all directions in a static liquid
External pressure exerted on an enclosed liquid changes the overall pressure.
Pascal’s Principle states that any change of pressure in an enclosed fluid is transmitted undiminished to all parts of the fluid.
ΔP = ρg Δh
magnitude of the gravitational effect (ΔP) is the product of the specific gravity or density of the blood (ρ), the acceleration due to gravity (980 cm/s/s) (g), and the vertical distance above or below the heart (Δh ) which is 0.77 mm Hg/cm at the density of normal blood.
HYDROSTATIC PRESSURE
The pressure at a given depth in a static liquid is a result of the weight of the liquid acting on a unit area at that depth plus any pressure acting on the surface of the liquid.
The pressure in any blood vessel below the level of the heart is increased, and the
pressure in any vessel above heart level is decreased by the effect of gravity.
Eg:-in the upright position, when the MAP 100
mm Hg, the mean pr in a large artery in the head (50 cm above ) is 62 mm Hg (100 - [0.77 x 50]) an
the pressure in a large artery in the foot (105 cm
below ) is 180 mm Hg (100 + [0.77 x 105]).

12. PRESSURE IN FLOWING FLUIDS
pressure in a flowing liquid depends on the details of the flow process, in contrast to the case of the static liquid
pressure gradient, which is defined as a pressure drop/ unit length.
For a uniform horizontal tube the pg will be the same at all points in the tube if a perfectly uniform flow pattern is maintained
Pressure gradient = P1 – P2 /L
( P1 = entry pressure,P2 = exit pressure, L = length of tubing)
Drops in pressure during flow represent losses in energy.
These losses are largely attributable to friction effects
Viscosity- force that oppose the flow

13. Flow Rate The Bernoulli Effect
POISEUILLE’S LAW
The Bernoulli Effect
predicts the volume of flow in moving fluids.
Q= (P¹-P²)π r4
8ήl
(Q = volume flow P1 = entry pressure P2 = exit pressure l = length of tubing r = radius of tube ή = viscosity of fluid)
As pressure difference or diameter of vessel ↑, volume flow ↑
As length or viscosity ↑, volume↓
predicts volume flow under laminar flow conditions in straight tubes where wall friction is not a significant factor.
When fluid flows steadily (without acceleration or deceleration) from one point in a system to another further downstream, its total energy content along any given streamline remains constant, provided there are no frictional losses. Bernoulli’s equation -rel between kinetic energy, gravitational potential energy, and pressure in a frictionless fluidsystem. predicts flow velocity and explains the presence of high-velocity jets obtained with Doppler instruments

16. Flow(Q) = pressure gradient (P)/resistance(R)
relationship bet bf , resistance, and pressure - modification of Ohm’s law for the flow of electrons in an electrical circuit:
Flow(Q) = pressure gradient (P)/resistance(R)
Blood is not an “ideal fluid” and energy (and pressure) is lost as flowing blood overcomes resistance.
Resistance to blood flow is a function of viscosity, vessel radius, and vessel length.
relationship is known as Poiseuille’s law
Resistance = 8 × viscosity × length/ π× radius4
Blood flow = π × radius4 × difference in pressure/8 × viscosity × length
Viscosity is also important in determining resistance. Exp relative to water.
plasma is 1.7 × viscosity of water and viscosity of blood is 3–4 × viscosity of water, the difference being due to blood cells and particularly hematocrit.

17. In the mammalian circulation, resistance is greatest at the level of the arterioles. effective area is much larger (capillaries)
arteriolar resistance can be regulated

19. R = diameter × velocity × density/viscosity
Transition from laminar to turbulent flow can be predicted by calculatingthe Reynold’s number, which is the ratio of inertial forces to viscous forces
R = diameter × velocity × density/viscosity
(viscosity (ή) of blood is Pa s, density (ρ) of blood is approximately 1050 kg/m3, velocity (V) of blood is in m/s, and the diameter of the tube is in m. Reynold’s number is dimensionless.)
Aorta- laminar to turbulent flow occurs at Nr bet 2000 and 2500
In atherosclerotic arteries &/or branch points,the critical Nr is much lower
In severe stenoses, turbulence can be initiated at Reynold’s numbers an order of magnitude less than in the theoretical, straight pipe.
Vessel diameter is doubly important for not only is it a direct variable in the equation, it also influences velocity
both velocity and diameter decrease in the microcirculation- laminar flow

20. Methods of Measuring Blood Pressure
INTRAVASCULAR METHOD
AUSCULTATORY METHOD (Stethoscope and cuff)
PALPATION METHOD (Pulses)
Reverend stephen Hales measured blood pressure of a horse using a vertical glass tube
Landois ( 1872 ) used a needle in an artery to direct spraying blood onto a moving paper surface-Hemautogram

21. Pressure wave A complex periodic fluctuation in force per unit area
A pressure wave is the cyclical force generated by cardiac muscle contraction
Its amplitude and duration are influenced by various mechanical and physiological parameters
1 .force of the contracting chamber
2.surrounding structures - contiguous chambers of the heart pericardium, lungs, vasculature
3.Physiological variables - heart rate, respiratory cycle

22. FOURIER ANALYSIS The complex waveform- (Fourier analysis)-
Mathematical summation of a series of simple sine waves of differing amplitude and frequency- harmonics
Fourier found that each pressure wave is a summation of a series of simple sine waves of differing amplitude and frequency

23. Wiggers principle
The essential physiologic information is contained within the 1st 10 harmonics of the pressure wave’s Fourier series
HR-120/min
Fundamental frequency- 2 Hz,
10th harmonic- 20 Hz
System with frequency response range upto 20 Hz suffice

24. To record pressure accurately, a system must respond with equal amplitude for a given input throughout the range of frequencies contained within the pressure wave
If components in a particular frequency range are either suppressed or exaggerated by the transducer system, the recorded signal will be a grossly distorted version of the original physiologic waveform

25. Transducer
Amplifier
Recorder
A pressure recording system is said to be adequate if the tenth harmonic of the fundamental frequency of a wave can be recorded with uniform sensitivity

26. Sensitivity-
ratio of the amplitude of the recorded signal to the amplitude of the input signal
Natural frequency-
Frequency at which the system oscillates when shock excited or
The frequency of an input pressure wave at which the ratio of output/input amplitude of a system is maximal
Directly proportional to lumen radius
Inversely proportional to cath length, √cath compliance, √liquid density
Highest natural frequency- short, wide-bore, stiff cath, low-density fluid without air bubbles- overdamped

27. Damping- dissipation of the energy of oscillation of a pressure measurement system owing to friction
Optimal damping

29. THE ELECTRICAL STRAIN GUAGE-WHEAT STONE BRIDGE

30. Pressure Measurement Systems
Fluid-filled Systems
Micromanometer Catheters

31. Fluid-filled Systems
fluid-filled catheter attached to a pressure transducer
pressure wave is transmitted by the fluid column within the catheter
Pressure measurement system should have the highest possible natural frequency and optimal damping
Data should be collected ,with the patient in steady state, in close proximity to one another and before introduction of radiographic contrast.
Accurate ‘zero’ reference is essential
Transducers must be caliberated frequently (before each rec)

32. The pressure transducer -calibrated against a known pressure, and the establishment of a zero reference undertaken at the start of the catheterization procedure
To “zero” the transducer, the transducer is placed at the level of the atria, which is approximately midchest
If the transducer is attached to the manifold and is therefore at variable positions during the procedure, a second fluid-filled catheter system should be attached to the transducer and positioned at the level of the midchest

34. Phlebostatic Axis Intersection of the 4th ICS and
½ the anterior-posterior diameter of the chest

36. ERROR & ARTIFACT DETERIORATION OF FREQUENCY RESPONSE
During the course of study deterioration fr response and damping
Air bubbles-> compliance- excessive damping and lower natural freq
High freq components of the wave sets the system in oscillation-pressure overshoot( early syst & diastole of ventr pressure curve)
flushing

37. Artifacts Movement artifact (WHIP Artifact)
Motion of tip of the catheter within the measured chamber → Enhance the fluid oscillations of the transducer system
May produce superimposed waves of ±10 mm Hg
Particularly common in PA
Render systolic and to a lesser extent diastolic pressures unreliable
No way to fix it internally
Stabilize externally
If whip noted - should indicate that to the physician and consider using mean pressures which are usually not affected

38. End hole artifact
An end-hole catheter measures an artificially elevated pressure
because of streaming or high velocity of the pressure wave
Flowing bld- K.E- sudden halt- converted to pressure
This added pressure may range from 2-10 mm Hg
Catheter impact artifact
When the catheter is struck by the walls or valves of the cardiac chambers
Common with the pigtail cath in the LV, where the MV hits the cath as they open in early diastole

39. Systolic P amplification in the periphery
Peak SBP in radial,brachial,femoral > peak SBP in central Ao mmHg
Mean arterial P remains same
Largely as a consequence of reflected wave from Ao bifurc, art branch, small peri vessls
Reinforce the peak and trough of the anterograde P wave

41. Micromanometer –Tipped Catheters
Fluid filled system-distortion of wave forms- artifacts, amplification of syst pressure in periphery, damping or augmentation of frequency response system.
For precise undistorted high fidelity pressure recordings
Micromamometer chips at the end of catheters
Interposing fluid column is eliminated
Have higher natural frequencies and more optimal damping characteristics
To assess pressure waveform contours in a tachy situation, rate of ventricular pressure rise(dp/dt) etc
Limitation- additional cost, fragility , time needed for properly calibrating and using the system

42. Techniques for determination of cardiac output
Fick Oxygen technique
Indicator dilution technique
Thermodilution technique
Angiographic technique

43. Adolph Fick 1870
The total uptake or release of any substance by an organ is the product of blood flow to the organ and arteriovenous oxygen difference of the substance
If no intracardiac shunt PBF=SBF
Pulmonary blood flow = oxygen consumption/ arteriovenous oxygen difference across the lungs
CO = O2 consumption (ml/min)
arterial O2 content - mixed venous (PA) O2 content
O2 consumption varies according to individual, by age and sex

44. cardiac output Fick Method- (CONSERVATION OF MASS) lung Flow =
rate of O2 consumption
O2 concentration of blood entering lung
O2 concentration of blood leaving lung
lung
Flow =
rate of O2 consumption
[O2] leaving – [O2] entering =
250 ml/min
190 – 140 ml/litre
= 5 litres/min

45. Assumptions made
Uptake of oxygen by the lungs from the blood is measured instead of measuring the rate at which oxygen is taken up from the lungs by the blood
Left ventricular or systemic arterial blood is sampled instead of pulmonary venous blood
Due to bronchial venous and thebesian venous drainage oxygen content of systemic arterial blood is 2 to 5ml/l lower than pulmonary venous blood

47. O2 content of room air is also measured
Douglas bag method
Polarographic method
Older
A timed sample of patients expired air is collected in a Douglas bag & analyzed for O2 content and ( Beckman oxygen analyzer) and volume
O2 content of room air is also measured
Oxygen consumption per l per minute is calculated
Metabolic rate meter by Waters instruments
Parts: oxygen hood /mask
Polarographic oxygen sensor cell
V o2=O2 content in the room air – O2 content in the air flowing past the polarographic cell
Respiratory quotient is assumed
Paramagnetic method
Paramagnetic sensor for measuring O2
Adjusts for temperature and partial pressure of water vapour
Calculates respiratory Q for each patient
Deltatrac II made by sensormedics

48. O2 consumption index – 125 ml / m2 BSA Dubois, nomograms
Assumed
O2 consumption index – 125 ml / m2
BSA Dubois, nomograms
× wgt .425 (kg) × height .725 (cm)
Mosteller = √(HT cm x Wt Kg )/ 60
Kendrick AH.Direct Fick CO: are assummed values of O2 consumption acceptable?Eur Heart J 1988;9:37

49. Arteriovenous difference and extraction reserve
The extraction of a given nutrient from the circulation is expressed as arteriovenous difference.
The factor by which arteriovenous diff can increase at constant flow -- extraction reserve
normal extraction reserve for oxygen - 3.
AV difference of O ml/L

50. Assumes prevalance of steady state
SOURCES OF ERROR
Assumes prevalance of steady state
Reflectance oximetry accurate only for a range 45%-98%
Improper collection of the mixed venous sample
O2 con- error-6% A-V O2 diff -error -5%
The total error Fick CO– about 10 %
Resting O2 consumption is 125 mL/m2, or 110 mL/m2 for older patients
6% error by assumption in trials
Cardiac output age and BSA dependent
Age 7 to 70 yrs to 2.5 litre /min /m2

51. Indicator dilution methods
Merely a specific application of fick’s general principle
“An indicator mixed into a unit volume of constantly flowing blood can be used to identify that volume of blood in time, provided the indicator remains in the system between injection and measurement and mixes completely in the blood”
Indocyanine green is the indicator usually used
Continous infusion & single injection method
It is injected as a bolus in to the pulmonary artery and samples are taken from the peripheral systemic artery
Severe allergic reactions can occur

52. General equation: mass of dye (Q g) Flow rate = ~
time of passage (t) = 0.5 min ~
average conc (X) = 2 mg/L
Amount of dye added = 5 mg
Average dye concentration = 2 mg/L
Therefore the volume that diluted the dye =
5mg/2mg per L = 2.5 L
Time it took to go past = 0.5 min
ie flow rate = L /0.5 min = 5 L/min
General equation:
mass of dye (Q g)
Flow rate = ~
average dye conc (X g/L) x time of passage (t min)

53. THERMODILUTION METHOD
Fegler (CONSERVATION OF ENERGY)
cold saline or 5% D
balloon-tipped flow-directed pvc catheter
thermistor at tip
opening 25 to 30 cm proximal to the tip
Via vein to PA (proximal opening –SVC or RA, thermistor –PA)
5 to 10 mL to proximal port
change in temperature at the thermistor recorded

54. Modification of Stewart-Hamilton conservation of heat equation
normal curve
sharp upstroke
smooth curve
mildly prolonged
downslope until baseline

55. area under the curve is inversely proportional to the flow rate in the pulmonary artery which equals the cardiac output in absence of intracardiac shunt

56. adv
Sources of error
easy widely available
No withdrawl of blood
No arterial puncture
Inert and inexpensive indicator
No recirculation –analysis simple
Less measurement variability and correlation with Fick.
Unreliable- TR,PR
Baseline temp fluctuation
Inaccurate in low flow- low output states (overestimation upto 35%)
Empirical correction factor to account for catheter warming may be inadequate

57. ANGIOGRAPHIC CO
Calculated by tracing end diastolic and end systolic images
SV= EDV-ESV
CO= ( EDV-ESV ) × HR
In regurgitation or AF- not accurate
But preferred over fick to measure co in calculation of valve areas in combined stenotic and regurgitant lesions
Erroneous in RWMA or structurally abnormal ventricles

58. METHOD
MOST RELIABLE
LEAST RELIABLE
FICK METHOD
LOW CO
HIGH CO
THERMODILUTION
PR, TR
INTRACARDIAC SHUNTS
ANGIORAPHIC
NL-SHAPED VENTRICLE
EXTENSIVE RWMA
DILATED VENTRICLE
AR,MR( CO >)

59. VASCULAR RESISTANCE Q = ΔP OHM’S LAW (V=IR) R
OVERSIMPLIFICATION- pulsatile flow in dynamic and diverse vascular beds

60. DETERMINATION OF VASCULAR RESISTANCE

62. VASCULAR IMPEDENCE
Vasc impedence –pulsatile pressure /pulsatile flow
Research use
Analogue is Vasc resistance

63. Principles of haemodynamic measurements: Pressure and flow measurements calculation of cardiac output Calculation of shunts valve area

64. Cardiac Catheterization: Shunt Detection
Oximetry Run (Dexter and his associates in 1947)
Early recirculation of indicator
Early appearance.of indicator in Rt heart
Angiography
Radio- nuclide techniques.

65. Detection, localization, and quantification of intracardiac shunts
several methods
indicator dilution method is of historical interest
Contrast angiography
Oximetry, or measurement of the oxygen saturations in various locations
goal of the oxygen saturation run is to measure differences in oxygen saturation in various chambers of the heart

66. Oxygen saturation run
Performed as a catheter is passed through the venous system, right heart, and pulmonary circulation.
samples - acquired with the patient breathing room air or a gas mixture ≤ 30% oxygen
place the catheter - PA first and then obtain samples as the catheter is withdrawn.
(difficulty advancing the catheter into the pulmonary artery)
ASSUMPTIONS
Body is in a steady state during the collection of samples
Complete mixing of blood is assumed in all chambers.
Blood samples should not be withdrawn into the syringe too rapidly.
( Matta et al. found that rapid aspiration increased oxygen saturations)

67. End-hole catheter (e. g. , Swan-G) or with side holes close to tip (e
End-hole catheter (e.g., Swan-G) or with side holes close to tip (e.g., GL)
CO by Fick method
O2 consumption calculated
2-ml samples under fluoroscopic + pressure wave
<7 minutes
VPCs, that site should be skipped until the rest of the run has been completed

68. Sites from which oxygen saturation should be measured when quantifying intracardiac shunts

69. Important formulas in quantifying shunts

71. MVO2

72. EFFECTIVE BLOOD FLOW- fraction of the mixed venous return received by the lungs without contamination by the shunt flow
EBF= O2 CONSUMPTION(ml/min)
( PvO2 - MV O2)
1. SIZE OF L R SHUNT (NO R L SHUNT)
= PBF – SBF
2 . SIZE OF L R SHUNT (R L SHUNT ⁺)
= PBF – EBF
3. SIZE OF R L SHUNT
= SBF - EBF

73. Limitations of Oximetry Run
Sample collection errors.
Lack of sensitivity (L-R shunts <20% of PBF not detected)
influence of Hb concentration
Assumed oxygen saturations
Assumed pulmonary vein saturation
“Non-physiologic” state
Calculated PVRI (basal and post-pulmonary vasodilator) has not been adequatelystandardized .

74. Level Step-Up Q.P./Qs Atrial >9% 1.5-1.9 ventricular >6% 1.3-1.5
Oximetry Run
Level Step-Up Q.P./Qs
Atrial >9%
ventricular >6%
Grt Vessel 5%
Any level %
( SVC - PA)

75. Quantification based on Qp/Qs
Qp/Qs Shunt Guidelines for Trt
< small medical
moderate Sx if risk is low
> large Sx
< R-L Sx contra-indicated

76. A ratio <1.5 → small L→R shunt A ratio ≥2.0 → large L→R shunt
Flow Ratio
A ratio <1.5 → small L→R shunt
A ratio ≥2.0 → large L→R shunt
A ratio betw 1.5 and 2.0 →intermediate
A ratio <1.0 → net R→L shunt
(irrev pulm vasc D)

77. PVRI
PVR/SVR
<8 WU
operable
<8-12 WU
borderline
>12 WU
>0.75
inoperable

78. Closure either percutaneously or surgically, may be considered :-
Class llb
Closure either percutaneously or surgically, may be considered :-
in the presence of net left-to-right shunting
pulmonary artery pressure less than two thirds systemic levels
PVR less than two thirds SVR or
when responsive to either pulmonary vd therapy or
test occlusion of the defect

79. Role of cardiac catheterization in assessment of operability
The calculated parameters by catheterization PVR and ratio of PVR to SVR -caveats - should not be taken at their face value in isolation.
Vasodilator testing in catheterization lab using 100% oxygen or oxygen with no- has not been shown to be of proven value and does not add significantly to decision making.
( Lock JE, Einzig S, Bass JL, Moller JH. The pulmonary vascular response to supplemental oxygen and its influence on operative results in children with ventricular septal defect. Pediatr Cardiol. 1982;3:41–6.
Balzer DT, Kort HW, Day RW, et al. Inhaled nitric oxide as a preoperative test (INOP Test I): The INOP Test Study Group. Circulation 2002;1060)
Patient with a PVRI of 6 Wood units & PVR/SVR ratio of 0.25 is considered operable.
PVRI > 10 Wood units & PVR/SVR ratio of 0.5 is clearly beyond the operable range.
Patients with PVRI and PVR/SVR ratio between these values fall in the gray zone
(National Consensus Meeting on “Management of Congenital Heart Diseases in India” held on 26thAugust 2007)

80. Operability-determination of the severity of PAH and the degree of vasoreactivity of the pulmonary circulation.
Agents used to elicit such reaction should ideally have an effect on PVR but not on the systemic circulation
Inhaled 100% oxygen mc.
recomm- short-acting vasodil - inhaled no, iv epoprostenol, or adenosine
An acute reduction of the mean PAP of 10 mmHg or greater with a resultant mean PAP of 40 mmHg or less without a fall in CO is considered a positive response to acute vasodilator testing
In patients with evidence of vasoreactivity during acute testing but high pulmonary vascular resistance and bidirectional shunting
- balloon test occlusion
A drop in CO &/ increase in RV filling pressures-may suggest
1)a low likelihood to benefit from permanent repair )higher perioperative risk

81. On O2 adm- if diastolic pressures fall significantly (10mm Hg) & mean pressure by about 5mm Hg- reversible PAP and operability.

82. Calculation Of Stenotic Valve Orifice Area

83. Gorlin Formula
Torricelli's law
1st formula
2nd formula
Combining both

84. Geometry of valve – flat valves have greater contraction co-efficient (for similar CSA and volume flow)

85. For the AV & PV, SEP is substituted for DFP
Antegrade flow across MV & TV occur in diastole, AV & PV occur in systole
For MV & TV
DFP(sec/beat) × HR (bpm)
CO in ml/min divided by sec/min during which there is flow
→ diastolic flow in cm3 /sec
For the AV & PV, SEP is substituted for DFP

86. DFP begins at MV opening(PCW-LV Crossover) & until end-diastole(peak of R in ECG) SEP begins with AV opening & until dicrotic notch/other evidence of AV closure

87. CO- ml/min DFP/SEP- sec/beat HR- beats/min C- empirical constant (0
CO- ml/min DFP/SEP- sec/beat HR- beats/min C- empirical constant (0.85-MVA,1.0- AVA) P- mm Hg ( 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 )

88. Aortic Valve Area
AVA= CO/(HR)(SEP)
44.3 √∆P

90. Pitfalls Peak – peak gradient alignment mismatch Distortion of pulse -FA Peripheral pulse amplification Catheter in LVOT Central aorta - pressure recovery Carballo’s sign

92. Doppler derived gradients- using CW doppler @ vena contracta
Catheter derived gradients- downstream vena contracta- pressure recovery
Pressure recovery is more across aortic than at mitral
prosthetic valve> native valve.
Pressure recovery- exaggerated in
Smaller aorta
Stiffer aorta
Hypertension
GRADIENT DERIVED BY CATH IS LOWER THAN DOPPLER DERIVED GRADIENT

93. Aortic Stenosis: Carabello’s Sign
Carabello’s Sign: Increase in aortic pressure while withdrawing catheter from Ao V – critical AS
An augmentation in periph SBPof >5 mm Hg at the time of LV catheter pullback indicates – signi AS
> 80% of pts with an AVA ≤0.5 cm2

94. LV-FA Systolic gradient
time delay/syst amplific/widening

96. LVOT-Ao Systolic gradient
Catheter tip in LVOT will measure a typical LV-P tracing but can underestimate true LV-Ao gradient by 30 mm Hg

97. ideal location for measuring gradient
may better reflect the actual overload on the myocardium

99. Mitral Valve Area
MVA= CO/(HR)(DFP) 37.7 √∆P

100. MVA-pitfalls
Calculation of cardiac output : Fick’s method - presence of MR - overestimate MVA Thermodilution method - not possible in presence of TR Confounding factors like anemia, fever AF & thyrotoxicosis Calibration errors PCWP tracing - delay in transmission over estimate LA pressure by 2 – 3 mmHg difficult to obtain wedge position confirm by noting mean Pr & oxymetry

101. Simplified valve formula for calculation of stenotic cardiac valve areas
Based on observation- HR × SEP/DFP × C ≈ 1 Hakki et al Differs from Gorlins by 18 ± 13% in HR

102. Valve Resistance
Mean Ao V Gradient/CO per sec of syst flow

103. Thank u

104. Valve area = cardiac output ÷ (HR X SEP)
V2 = (CV)2 X 2Gh
V= (CV) x √ 2Gh
(h = pressure gradientG = gravitational constant (980 cm/sec2) for conversion cmH2 to units pressure. Cv- coefficient velocity for correcting energy loss (pressure energy- kinetic energy)
A= F/V
Flow rate= cardiac output/ duration of systole or diastole (SEP/DFP X HR)
Valve area = cardiac output ÷ (HR X SEP)
44.3 X C X √ 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 )
Modification: HAKKE
cardiac output (L/ min)
√ MPG
Heart rate: / min

105. AVA Pull back hemodynamics : Peak – peak gradient alignment mismatch
Distortion of pulse - femoral artery
peripheral pulse amplification
catheter in LVOT
central aorta - pressure recovery
Carballo’s sign

108. Reflected waves
The forward P wave is modified by summation with a reflected P wave
Major effective reflection sites in humans- terminal abd Ao (↑reflected W and hence peak Ao P in B/L femoral occlu)

109. Factors affecting magnitude of reflected waves
Augmenting reflected waves
Vasoconstriction
CCF
HTN
Ao/iliofemoral obstruct
Valsalva-after release
Diminishing reflected waves
Vasodilation-fever,NTG
Hypovolemia
Hypotension
Valsalva-strain phase

110. The current definition of PAH relies on the presence of a mean pulmonary arterial pressure exceeding 25 mmHg at rest or 30 mmHg during exercise, a left atrial pressure below 15 mmHg, and a normal resting cardiac output, suggesting a resting pulmonary vascular resistance above 3 Wood units.
5% to 10% of patients with CHD (mostly those with late or no repair) develop PAH
Venice classification
approximately 4% of individuals with CHD followed in tertiary centers develop Eisenmenger syndrome, as opposed to 8% prior to the current operative era
VSDs are the most common simple defects causing PAH, with an estimated 10% of all VSDs and 50% of large VSDs-ES