shunt calculation final in structural heart disease

cardiology

1. ASSESSMENT OF SHUNT
LESIONS
DR. BHUSHAN PATIL

3. Salient features of all the shunt lesions:
1)Shunt would lead to volume overloads of
the chambers it feeds (particularly in relation to the
tricuspid valves.
Shunt proximal to tricuspid valve -volume overloading of RA and RV
Lesion beyond tricuspid valve -volume overloading of LA and LV.
2) Magnitude of the chamber enlargement depends
upon the magnitude of the shunt.
significant RA and RV enlargement -pretricuspidshunt.
significant LA and LV enlargement -post-tricuspid shunt.

4. Salient features of all the shunt lesions:
3) Pressure of the investigated chamber would rise :
Not only on account of distal obstruction
It would be because of the transmitted pressures
from the adjacent chambers on account of the shunt.
4) Magnitude of the gradient from a chamber outflow
would be dependent on the magnitude of shunt into
the chamber.

5. Salient features of all the shunt lesions:
5) Shunt lesion almost always signifies a
communication between 2 chamber, the gradient
between the 2 chambers can guide as to the magnitude
of the shunt lesion or the size of the defect.
6) The size of the defect in 2 dimensions may be a
useful guide in deciding the degree of shunt. It also is
useful to help the interventional modality

6. ASSESSMENT OF SHUNT LESIONS

7. Assessment of shunt lesions must be preceded by:
•History
•Physical examination
•Chest X-ray
•Arterial blood gas (ABG) estimation
•ECG
•Echocardiography.
•These modalities provide independent useful
information on the status of the pulmonary
vasculature.

8. •There are occasions when despite equivocal
cardiac catheterization data, defects have
been successfully corrected based on a
comprehensive clinical and noninvasive
evaluation.

11. •Presence of clinical cyanosis or saturations <90% is a
strong predictor of inoperability.
•Whereas the clear detection of a mid diastolic
murmur on serial assessment strongly favours
operability.

12. Evaluation of left to right shunts by
echocardiography

13. Stepwise approach (on echocardiography)
Stepwise approach (on echocardiography) for
evaluation of any shunt lesion involves:
1) Determine the presence of shunt lesion
2) Determine the volume overload (and complication)
on account of the shunt lesion
3) Defining the size of the lesion and its location
4) Define the lesion on echocardiography for operability
5) If suitable to decide the relevant modality of
treatment

14. Step 1: suspect the shunt lesion
Visualization of an accessory flow into the chamber
Any shunt lesion will lead to the chamber
enlargement into which it drains
Tricuspid valve an important landmark
•A pretricuspidshunt would lead to RA and RV
enlargement
•A post-tricuspid shunt would lead to left atrial and
left ventricular enlargement

15. Step 2: a recall of the shunt lesions
Pretricuspidshunts:
atrial septal defect (ASD)
anomalouspulmonaryvenousdrainage,
systemic AV fistulae
Ruptured sinus of Valsalva to right atrium
Coronary AV fistulae to right atrium
Gerbodedefect (left ventricle to right atrial
shunt)

16. Step 2: a recall of the shunt lesions
Post-tricuspid shunt:
Ventricular septal defect (VSD)
aortopulmonary window (APW)
Patent ductus arteriosus (PDA)
Pulmonary AV fistulae
Coronary AV fistulae
RSOV to any structure beyond tricuspid valve,
aortopulmonary collaterals

17. Atrial septal defects
Objectives on echocardiography
1.To diagnose atrial septal defect, asses its anatomical
site and size.
2.To assess the direction and quantum of flow.
3.To assess the degree of pulmonary arterial
hypertension.
4.To assess atrioventricular valve anomalies,
pulmonary veins and pulmonary valve stenosis.

18. Atrial septal defects
ASD classification
a.patent foramen ovale(PFO)
b.Ostiumsecundumatrial septal defect
c.Sinus venosusdefect
d.Coronary sinus atrial septa defect.
e.ostium primum atrial septal defect

19. Evaluation on echocardiography
•Abnormal interventricular septal motion and
enlarged RA and RV are indirect evidence of left to
right shunt at atrial level.
•The best views to directly visualize the atrial septal
defect are subcostal coronal and sagittal views.
•Atrial septal defect will be diagnosed by a dropout in
the interatrial septum with flow across the defect on
Doppler interrogation

20. Evaluation on echocardiography
•When the defect is visualized its relationship to the
SVC /IVC should be evaluated.
•If the SVC forms the roof of the defect -SVC sinus
venous type.
•If the IVC straddles the defect -IVC type.
•The defects in the center of the atrial septum
involving the fossa ovalis area are fossa ovalis
defects/ OS ASD.

21. Evaluation on echocardiography
•Defect in the lower most part of the interatrial
septum with atrioventricular valves attached at the
same level -ostiumprimum defects.
•It should also be viewed in apical four chamber and
short axis views.

22. Evaluation on echocardiography
•Color flow mapping across the defect will show the
direction of flow and also presence or absence of any
regurgitation.
•Doppler velocities across all valves should be taken,
in particular the pulmonary valve to look for any
pulmonary stenosis.

23. Atrial septal defects
Direction of shunt
•Dominant shunt occurs from left to right.
•Left to right shunt occurs mainly during mid to late
systole as ‘v’ wave of left atria is larger than right
atria .
•The second wave of left to right shunt occur with
atrial contraction.

24. The following pattern of shunting can be appreciated in patient
of ASD.
1)Left to right shunt: ASD without PAH,thisis a commonest
pattern of shunting.
2) Right to left shunt: In ASD right to left shunting will occur in
following situation
a) Severe PAH.
b) Hypoplasiaof right sided chambers.
c) Severe pulmonary stenosiswith right ventricular
hypertrophy or hypertension.
d) Obligatory right to left shunt even in absence of significant
PAH is seen in tricuspid atresia, TAPVC.

25. 3) Bidirectional shunting :seen most commonly during
the stage of progression of PAH
•For the estimation of pulmonary arterial pressure the
peak gradient of tricuspid regurgitation should be
taken.
•If pulmonary regurgitation is present the pressure
derived from the peak diastolic velocity will reflect
the pulmonary arterial mean pressure.

26. Evaluation on echocardiography
Calculation of shunt in ASD
•Because of its fallacy calculation of shunts by
echocardiography is rarely practiced.
•Quantitative assessment of significant shunt is
assessed by its impact on RA and RV chamber size.
•“significant” shunt is will be associated with dilated
RA and RV.
•The disadvantage of this visual assessment is that
progressive enlargement of RA and RV can occur
with increasing pulmonary artery pressures.

27. Ventricular septal defect
Objectives of echocardiography
Confirm ventricular septal defect (VSD).
Determine the size and morphological location of
VSDs.
Rule out associated lesions.
Assessment of chamber size and wall thickness.
Estimation of shunt size (pulmonary/systemic flow
ratio).
Estimate right ventricular and pulmonary arterial
pressures.

28. Classification of VSD
Ventricular septaldefects can be classified into
following types:
1.perimembranous ventricular septal defect
2.muscular ventricular septaldefect
i. muscular inlet
ii. muscular outlet
iii. trabeculardefect
3.doubly committed ventricular septaldefect
4.inlet ventricular septaldefect

30. Size of ventricular septal defect
•The judgment of size of defect is generally made on
hemodynamic grounds (degree of left to right shunt,
presence of volume overload, and pulmonary artery
pressure).
•Comparative size: VSD size is defined in relation to
aortic root size.
Small -less than 1/3rd of aortic root diameter,
Moderate -1/ 3rd to 2/3rd of aortic root diameter
Large VSD-> 2/3
rd
aortic root

31. .
Hemodynamic classification: uses the pressure
differential across the left to right ventricle to classify
defects.
1.large or nonrestrictive defect : there is equalization
of pressure between two ventricles in absence of
pulmonary stenosis
2.Restrictive defect: pressure gradient of more than
60 mmHg (VSD peak velocity more than 4 m/s)
3.moderately restrictive : pressure difference of 25 -
60 mmHg (VSD peak velocity 2.5 -4 m/s).

32. Direction of shunt
•Uncomplicated nonrestrictive VSD, pressure between
the two ventricles is similar.
•Low pulmonary vascular resistance –dominant
occurs from left to right during systole
•Increase in left ventricle end diastolic pressure left to
right shunt will persist during diastole also.

33. •A typical ‘M’ shaped flow pattern is being described
in patients with nonrestrictive VSD.
•As left ventricle contraction starts early and last
longer than right ventricle.
•With onset of systole flow occur from left to right,
with decrease in degree of shunt during mid systole
as pressure between two ventricles equalized.
•In later part of systole as right ventricle relaxes left to
right shunt dominates.

34. •Restrictive VSD, left to right shunting occurs
throughout systole.
•In some small muscular VSD, left to right shunt
occurs only during a portion of systole, presumably
because of closure of muscular ventricular septal
defect in mid systole with ventricular contraction
•Nonrestrictive ventricular septal defect with high
pulmonary vascular resistance, direction of flow can
be bidirectional or dominantly right to left.

35. •With associated pulmonary stenosis, there may be
isolated right to left shunt.
•With severe right ventricular outflow obstruction, if
ventricular septal defect is small, one can get a
turbulent jet of right to left shunt with suprasystemic
right ventricle systolic pressure.
•One should also look for any left ventricle to right
atrial shunt as high velocity of left ventricle to right
atrial jet can be misinterpreted as elevated right
ventricle pressure.

36. •Pulsed and continuous wave Doppler examination is
used to assess:
-Direction of shunt across VSD.
-Pressure gradient across the defect (difference of left
ventricle –right ventricle systolic pressure).
-Right ventricle pressure (by VSD gradient and peak
gradient of tricuspid regurgitation jet).
-Diastolic function of both ventricles.

37. Pressure gradient across ventricular septal defect
•While taking continuous wave Doppler across VSD,
the cursor should be well aligned with VSD jet on
color flowmapping.
•The velocity of the VSD shunt can be determined
using the Bernoulli’s equation.
•This will give the difference between the left and
right ventricular systolic pressure.

38. •The left ventricular systolic pressure is derived from
the systolic blood pressure (provided there is no left
ventricular out flow obstruction)
•Right ventricular pressure = Systolic blood pressure -
VSD jet peak gradient
•This equation has been found to have good
correlation with cardiac catheterization derived right
ventricle systolic pressure.

39. •Sometimes the jet velocity may not reflect the
interventricular pressure gradient accurately because
proper alignment of the Doppler beam with the jet is
not possible .
•Determining the right ventricular pressure from
tricuspid insufficiency jet velocity (which may be
found in som cases) is also very useful.

40. Assessment of suitability for device closure
•Percutaneous closure for mid muscular VSD and
perimembranous VSD can be done.
•While assessing the child for device closure of
muscular defect, the defect should be at least 5mm
away from atrioventricular valves and semilunar
valves

41. Patent ductus arteriosus (PDA)
Objectives of echocardiography
•The presence of a duct
•Detailed definition of ductus
-Size of the duct
-Type of duct
•The hemodynamic significance of a duct
-Direction of shunt
-Pulmonary arterial pressure
-Quantification of shunt
•Associated defects

42. Various views to define the ductus
1)DuctalView : high parasternalwindow just beneath
the left clavicle. Short axis cut of the great vessel -
the transducer is rotated anticlockwise in gradual
motion.
2) Suprasternalview:
a) Suprasternallong axis view
b) Suprasternalshort axis view
c) Modified ductalview : suprasternallong axis view
the transducer is rotated anticlockwise -slight
anterior tilt .

43. Measurements on the duct by echocardiography
include:
a)Size of the narrowest part of the duct -in the
majority of cases this would be at the site of
pulmonary artery insertion.
b) Size of the ampullaof duct
c) The length of the duct that is necessary to determine
adequacy of coil/device/stent placement.

44. •In patients with inadequate windows, the size of
the duct can be determined by the narrowest width
of the color flow across the duct.
•This, however, always overestimates the ductalsize
and gives only a rough estimate

45. Hemodynamic significance
•Hemodynamic significance of ductus arteriosus can
be assessed by evidence of
-volume overload of LA and LV
-direction of shunt
-pulmonary arterial pressure.
Chamber dimensions:
•Left atrial enlargement signifies increased
pulmonary venous return because of left-to-right
ductal shunting.

46. •The reference measure is the ratio of the left atria to
aorta at the level of the aortic valve (the LA: Ao
ratio)by Mmode echocardiography in parasternal
long axis view.
•A LA: Ao ratio >1.3:1indicates a significant shunt.
•LV will enlarge as cardiac output increases with both
increased pulmonary venous return and with
increased diastolic run-off from the systemic
circulation.

47. Direction of shunt and pulmonary arterial pressure
•On color flow mapping, small duct with normal
pulmonary artery pressure is displayed as a mosaic
flow from descending aorta to pulmonary artery.
•With large duct, and low pulmonary vascular
resistance, the duct jet appears as predominantly red
flow with minimal aliasing.
•In patients with severe pulmonary arterial
hypertension, on color flow mapping, there will be
bidirectional shunt.

48. Continuous wave Doppler examination of ductus
arteriosus
•By the use of continuous wave Doppler, direction of
shunt in relation to cardiac cycle can be detected
•Pulmonary arterial pressure =systolic blood pressure
-pressure gradient cross duct
•Small to moderate sized PDA and normal or mildly
elevated pulmonary artery pressure -continuous flow
toward the transducer with peak in late systole

49. •In large duct with pulmonary arterial hypertension -
bi-directional shunting on Doppler imaging of duct,
right to left in systole and left to right in diastole.
•With further rise in pulmonary vascular resistance,
right to left shunt begins in diastole extending to
systole
•With duct dependent systemic circulation and severe
pulmonary arterial hypertension, there will be
isolated right to left shunting across the duct.

50. CARDIAC CATHETERISATIONAND
ANGIOGRAPHY

51. Cardiac Output Measurement
•Quantity of blood delivered to the systemic
circulation per unit time
•Techniques
–Fick-Oxygen Method
–Indicator-Dilution Methods
•Indocyanine Green
•Thermodilution

52. Cardiac Output Measurement
Fick Oxygen Method
•Fick Principle: The total uptake or release of any substance by
an organ is the product of blood flow to the organ and the
arteriovenous concentration difference of the substance.
•As applied to lungs, the substance released to the blood is
oxygen, oxygen consumption is the product of arteriovenous
difference of oxygen across the lungs and pulmonary blood
flow.
•In the absence of a shunt, systemic blood flow (Qs) is
estimated by pulmonary blood flow (Qp).
Q
p=
Oxygen consumption
Arteriovenous O
2difference

53. O
2Consumption
1.PolarographicO
2Method with metabolic rate
meter
2.Douglas bag method
3.Nomogramsfrom Lafarge
•1 met = 3.5 ml/min/kg body weight
•70 kg man = 245 ml/min = 150 ml/min/m
2
•Woman = 125 ml/min/m
2
•Young infant = 200 ml/min/m
2
•Higher consumption if patient is febrile,
tachycardia, agitated

54. Cardiac Output Measurement
Fick Oxygen Method: O
2Consumption
•PolarographicO
2Method
–Metabolic rate meter
–Device contains a polarographicoxygen sensor
cell, a hood, and a blower of variable speed
connected to a servocontrolloop with an
oxygen sensor.
–The MRM adjusts the variable-speed blower to
maintain a unidirectional flow of air from the
room through the hood and via a connecting
hose to the polarographicoxygen-sensing cell.

55. Cardiac Output Measurement
Fick Oxygen Method: O
2Consumption
•Polarographic O
2Method
V
M= V
R + V
E-V
I
V
M = Blower Discharge Rate
V
R = Room Air Entry Rate
V
I = Patient Inhalation Rate
V
E = Patient Exhalation Rate
V
O2 = (F
RO
2 x V
R) -(F
MO
2 x V
M)
F
RO
2 = Fractional room air O2 content = 0.209
F
MO
2 = Fractional content of O2 flowing past polarographic cell
V
R V
M
V
E
V
I

56. Cardiac Output Measurement
Fick Oxygen Method: O
2Consumption
•Polarographic O
2Method
V
O2 = (F
RO
2 x V
R) -(F
MO
2 x V
M)
V
O2 = V
M (0.209 -F
MO
2) + 0.209 (V
I -V
E)
Servocontrolled system adjusts VM to keep fractional O2
content of air moving past polarographic sensor (FMO2) at
0.199
V
O2 = 0.01 (V
M) + 0.209 (V
I -V
E) Respiratory
quotient
RQ = V
I/ V
E=
1.0
V
O2 = 0.01 (V
M)

57. Cardiac Output Measurement
Fick Oxygen Method: O
2Consumption
•Douglas Bag Method
–Volumetric technique for measuring O2
–Analyzes the collection of expired air
–Utilizes a special mouthpiece and nose clip so
that patient breathes only through mouth
–A 2-way valve permits entry of room air while
causing all expired air to be collected in the
Douglas bag
–Volume of air expired in a timed sample (3
min) is measured with a Tissot spirometer

59. Cardiac Output Measurement
Fick Oxygen Method: AV O
2Difference
•Sampling technique
–Mixed venous sample
•Collect from pulmonary artery
•Collection from more proximal site may result in error with
left-right shunting
–Arterial sample
•Ideal source: pulmonary vein
•Alternative sites: LV, peripheral arterial
–If arterial dessaturation (SaO2 < 95%) present, right-to-left shunt
must be excluded
•Measurement
–Reflectance (optical absorbance) oximetry

60. Cardiac Output Measurement
Fick Oxygen Method: AV O
2Difference
O
2carrying capacity (mL O
2 / L blood) =
1.36 mL O
2 / gm Hgb x 10 mL/dL x Hgb (gm/dL)
Step 1: Theoretical oxygen carrying capacity
Step 2: Determine arterial oxygen content
Arterial O
2content = Arterial saturation x O
2carrying capacity
Step 3: Determine mixed venous oxygen content
AV O
2difference = Arterial O2 content -Mixed venous O
2 content
Step 3: Determine A-V O
2oxygen difference
Mixed venous O
2content = MV saturation x O
2carrying capacity
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 5
th
Edition. Baltimore: Williams
and Wilkins, 1996.

61. Cardiac Output Measurement
Fick Oxygen Method
Fick oxygen method total error 10%
Error in O2 consumption 6%
Error in AV O2 difference 5%. Narrow AV O2 differences more
subject to error, and therefore Fick method is most accurate in
low cardiac output states
Sources of Error
Incomplete collection of expired air (Douglas bag)
Underestimate O2 consumption and CO
Respiratory quotient = 1
Volume of CO2 expired is not equal to O2 inspired
Leads to underestimation of O2 consumption and CO
Incorrect timing of expired air collection (Douglas bag)

62. Cardiac Output Measurement
Fick Oxygen Method
Sources of Error
Spectophotometric determination of blood oxygen saturation
Changes in mean pulmonary volume
Douglas bag and MRM measure amount of O2 entering lungs, not
actual oxygen consumption
Patient may progressively increase or decrease pulmonary volume
during sample collection. If patient relaxes and breathes smaller
volumes, CO is underestimated
Improper collection of mixed venous blood sample
Contamination with PCW blood
Sampling from more proximal site

63. Cardiac Output Measurement
Indicator Dilution Methods
•Requirements
–Bolus of indicator substance which mixes
completely with blood and whose concentration
can be measured
–Indicator is neither added nor subtracted from
blood during passage between injection and
sampling sites
–Most of sample must pass the sampling site before
recirculation occurs
–Indicator must go through a portion of circulation
where all the blood of the body becomes mixed
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 5
th
Edition. Baltimore: Williams
and Wilkins, 1996.

64. Cardiac Output Measurement
Indicator Dilution Methods
Indicators
Indocyanine Green
Thermodilution (Indicator = Cold)
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
h
Edition. Baltimore: Williams and
Wilkins, 1996.
CO =


0

Indicator amount
C (t) dt
C = concentration
of indicator
Stewart-Hamilton Equation
CO =
Indicator amount (mg) x 60 sec/min
mean indicator concentration (mg/mL) x curve duration

65. Cardiac Output Measurement
Indocyanine Green Method
•Indocyanine green (volume and concentration fixed)
injected as a bolus into right side of circulation (pulmonary
artery)
•Samples taken from peripheral artery, withdrawing
continuously at a fixed rate
•Indocyanine green concentration measured by
densitometry
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
th
Edition. Baltimore: Williams
and Wilkins, 1996.
Concentration
Recirculation
Extrapolation
of plot
time
CO =
(C x t )
I
(C x t)
CO inversely
proportional
to area under
curve

66. Cardiac Output Measurement
Thermodilution Method
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
th
Edition. Baltimore: Williams
and Wilkins, 1996.
CO =


0

V
I(T
B-T
I) (S
IxC
I/ S
BxC
B) x 60
T
Bdt
V
I= volume of injectate
S
I, S
B= specific gravity of injectate and blood
T
I= temperature of injectate
C
I, C
B= specific heat of injectate and blood
T
B= change in temperature measured downstream

67. Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 5
th
Edition. Baltimore: Williams
and Wilkins, 1996.
Cardiac Output Measurement
Thermodilution Method
•Sources of Error (±15%)
–Unreliable in tricuspid regurgitation
–Baseline temperature of blood in pulmonary artery may fluctuate
with respiratory and cardiac cycles
–Loss of injectate with low cardiac output states
(CO < 3.5 L/min) due to warming of blood by walls of cardiac
chambers and surrounding tissues. The reduction in T
Bat
pulmonary arterial sampling site will result in overestimation of
cardiac output
–Empirical correction factor (0.825) corrects for catheter warming
but will not account for warming of injectate in syringe by the hand

68. SVR =
Vascular Resistance (R=V/I)
Ao -RA
Q
s
PVR =
PA -LA
Q
p
Normal reference values
Woods Unit x 80 = Metric Units
10 –20 770 –1500
0.25 –1.5 20 –120
Systemic vascular resistance
Pulmonary vascular resistance

69. Vascular Resistance
Poiseuille’s Law
Q =
(P
i–P
o) r
4
8 η L
Pir
P
oP
i
LPi –Po = inflow –outflow pressure
r = radius of tube
η= viscosity of the fluid
L= length of tube
Q = volume flow
Resistance =
8 η LP
Q
=
r
4
In vascular
system, key
factor is radius
of vessel

70. •It has been suggested that resistance ratio PVR/SVR
be used as a criterion for operability in dealing with
congenital heart disease.
Normally : 0 . 2 5 .
0 . 2 5 t o 0 . 5 0 : moderate pulmonary vascular
disease,
values higher than 0. 75 -severe pulmonary
vascular disease.
When the PVR/SVR resistance ratio is >1 . 0 , surgical
correction of the congenital defect is considered
contraindicated because of the severity of the
pulmonary vascular disease.

71. Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
th
Edition. Baltimore: Williams
and Wilkins, 1996.
Vascular Resistance
Systemic Vascular Resistance
•Increased
–Systemic HTN
–Cardiogenic shock with compensatory arteriolar
constriction
•Decreased
–Inappropriately high cardiac output
•Arteriovenousfistula
•Severe anemia
•High fever
•Sepsis
•Thyrotoxicosis

72. Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
th
Edition. Baltimore: Williams
and Wilkins, 1996.
Vascular Resistance
Pulmonary Vascular Resistance
•Increased
–Primary lung disease
–Eisenmenger syndrome
–Elevated pulmonary venous pressure
•Left-sided myocardial dysfunction
•Mitral / Aortic valve disease

73. Shunt Detection
•Arterial hypoxia
–Pulmonary causes corrects with ventilation/oxygen
–Right to left shuntdoes not correct with O
2
•High PA saturation (>80%) due to left to right
shunt
•Obtain O2 saturations in sequential chambers,
identifying both step-up and drop-off in O2 sat
•Insensitive for small shunts (< 1.3:1)

74. Shunt Detection & Measurement
Oximetric Methods
•Obtain O2 saturations in
sequential chambers,
identifying both step-up
and drop-off in O2 sat
•Insensitive for small
shunts (< 1.3:1)
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
h
Edition. Baltimore: Williams and
Wilkins, 1996.

75. Shunt Detection & Measurement
Oximetry Run
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 7
h
Edition. Baltimore: Williams and
Wilkins, 1996.
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
•IVC, L4-5 level
•IVC, above diaphragm
•SVC, innominate
•SVC, at RA
•RA, high
•RA, mid
•RA, low
•RV, mid
•RV, apex
•RV, outflow tract
•PA, main
•PA, right or left
•Left ventricle
•Aorta, distal to ductus

76. Shunt Detection & Measurement
Oximetric Methods
RA receives blood from several sources
SVC: approximates true systemic venous saturation
IVC: renal extraction is low
Coronary sinus: high extraction
FlammEquation:
in exercise study-more weightage to IVC
Mixed venous saturation = 2 IVC + SVC/ 3
Mixed venous saturation =
3 (SVC) + IVC
4

78. Shunt Detection & Measurement
Oximetric Methods
•Fick Principle: The total
uptake or release of any
substance by an organ is the
product of blood flow to the
organ and the arteriovenous
concentration difference of
the substance.
–Pulmonary circulation (Qp)
utilizes PA and PV saturations
RA (MV)
RV
LA (PV)
LV
PA Ao
Lungs

79. •Pulmonary blood flow is calculated by the
same formula used in the standard Fick
equation:

80. Shunt Detection & Measurement
Oximetric Methods
•Fick Principle: The total
uptake or release of any
substance by an organ is the
product of blood flow to the
organ and the arteriovenous
concentration difference of
the substance.
–Systemic circulation (Qs)
utilizes MV and Ao saturations
RA (MV)
RV
LA (PV)
LV
Body
PA Ao

81. SYSTEMIC blood flow is calculated by the same
formula used
in the standard Fickequation:

82. •If there is no evidence of an associated right-
to-left shunt, the left-to-right shunt is
calculated by

83. Calculation of Bidirectional Shunts
•A simplified approach to the calculation of
simultaneous right-to-left and left-to-right (also
known as bidirectional) shunts makes use of a
hypothetic quantity known as the effective blood
flow , the flow that would exist in the absence of any
left-to-right or right-to-left shunting:

84. •The approximate left-to-right shunt then
equals
Qp -Qeff
•the approximate right-to-left shunt equals
Qs -Qeff·

85. •this effective blood flow approach is an
approximation of the significantly more
complex formula shown in Eq.

86. Shunt Detection & Measurement
Left-to-Right Shunt
Qp / Qs Ratio =
(PvO
2–PaO
2)
(AoO
2–MVO
2)

87. Shunt Detection & Measurement
Indocyanine Green Method
Indocyanine green (1 cc) injected as a bolus into right side
of circulation (pulmonary artery)
Concentration
measured from
peripheral artery
Appearance and
washout of dye
produces initial 1
st
pass curve followed
by recirculation in
normal adults
Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 5
th
Edition. Baltimore: Williams
and Wilkins, 1996.

88. Shunt Detection & Measurement
Left-to-Right Shunt

89. Baim DS and Grossman W. Cardiac Catheterization, Angiography, and Intervention. 5
th
Edition. Baltimore: Williams
and Wilkins, 1996.
Shunt Detection & Measurement
Right-to-Left Shunt

90. Shunt Detection & Measurement
Indocyanine Green Method
Bashore, TM. Congenital Heart Disease in Adults. The Measurement of Intracardiac Shunts. In: CATHSAP II.
Bethesda: American College of Cardiology, 2001.

92. Atrial Septa l Defect

93. •Mvo2 = (3 [ 6 7 . 5 ] + 1 [ 73 ] ) / 4 = 69%
•O2 consumption = 240 mL, hemoglobin
concentration is 14 g%,
•oxygen content of PV = 183 mLo2/liter
•oxygen content of PA = 1 5 2 mL02/liter
•Qp= 7 . 74 Umin
•Qs = 4 . 7 Umin
•Qp/Qs, in this example is 7. 74/4 . 7 = 1 . 6 5 ,
•and the magnitude of the left-to-right shunt is
7 . 7 -4 . 7 = 3 Umin

94. SUMMARY

102. THANK YOU