I'm afraid I don't have enough information to answer these questions. The document provided is an overview of techniques for detecting intracardiac shunts and quantifying cardiac output and shunt flow. It does not include a specific patient case. Could you please provide more details about a patient for me to reference in answering your questions?

1. Dr. Fuad Farooq
Resident Cardiology
Aga Khan University Hospital

2.  Normal circulation
 Left to right shunting of blood as in ASD,VSD and PDA
 Unoxygenated blood can be shunted from the right
heart to the left heart - Eisenmenger syndrome
 Intracardiac shunts can be either congenital or
acquired e.g., VSD as a complication of myocardial
infarction

3.  Detection, localization and quantification of
intracardiac shunts are an integral part of the
hemodynamic evaluation in these patients

4.  Intracardiac shunting of blood results when there is an
opening between the right and left heart chambers and
a pressure difference between the connected
chambers
 Pressures on the left side of the heart are generally
higher than on the right side so most shunts are
predominantly left to right although right to left and
bidirectional shunts are seen (predominantly in
Eisenmenger syndrome)

5.  Many techniques are available for the detection
intracardiac shunts
• Indicator dilution method – Injecting indocyanine
green into a right sided heart chambers and then
monitoring its appearance in the systemic
circulation
• Contrast angiography – Contrast dye is injected into
high pressure chamber of suspected shunt
• Oximetry run – Most frequently used measurement
of the oxygen saturations in various locations in the
venous system and the right heart

9.  Basic technique for detecting and quantifying left to
right shunts
 Oxygen content or percent saturation is measured in
blood samples drawn sequentially from the pulmonary
artery, right ventricle, right atrium, superior vena cava
and inferior vena cava
 A left to right shunt may be detected and localized if a
significant step-up in blood oxygen saturation is found
in one of the right heart chambers

10.  Samples need to be acquired with the patient
breathing room air or a gas mixture containing no more
than a maximum of 30% oxygen
 Saturation data may be inaccurate in patients breathing
more than 30% oxygen, as a significant amount of
oxygen may be present in dissolved form in the
pulmonary venous sample
 Dissolved oxygen is not factored into calculations when
saturations are used and thus pulmonary flow will be
overestimated and the amount of shunt exaggerated
Heart 2001;85:113–120.

11. The simplest way to screen for a left to right shunt is to
sample SVC and pulmonary artery blood and measure
the difference in O2 saturation if >=8%, a left to right
shunt may be present at atrial, ventricular or great
vessel level, and a full oximetry run should be done

12.  Samples are obtain (2-mL) from each of the following locations
with the end hole catheter

13.  To ensure the results are as accurate as possible, the
samples must be collected as close in time as good
technique permits
 Blood samples should not be withdrawn into the
syringe too rapidly, “rapid aspiration increased oxygen
saturations”
 Complete mixing of blood is assumed in all chambers
Matta et al. Anesthesiology 1997;86:806–808.

14.  Oximetry method of quantifying shunts loses accuracy
when determining small shunts or in the presence of
high cardiac output (which decreases AVO2 difference)
 The magnitude of the step-up varies with the oxygen
carrying capacity of blood
 Relationship between the magnitude of step-up and the
shunt flow is nonlinear and with increasing left to right
shunting, a given change in shunt flow produces less of
a change in the saturation step-up

15.  Saturation step-ups are increased if
hemoglobin concentration is low or cardiac
output is low

16. Hillis et al. found that the difference between RA and PA
saturations in 980 patients without intracardiac shunts was
2.3% ± 1.7%. In this same population,the difference between
SVC and RA saturations was 3.9% ± 2.4%
Using threshold values of 8.7% and 5.7% respectively,
between SVC to RA and RA to PA as “cut-offs” to identify
patients with intracardiac shunts had excellent sensitivity
and specificity
Am J Cardiol 1986;58:129–132

17. Level of shunt Difference in
O2 saturation
Differential diagnosis
Atrial
(SVC/IVC to RA)
>7% ASD; PAPVD; Ruptured sinus of
Valsalva; VSD with TR; Coronary to
RA fistula
Ventricular
(RA to RV)
>5% VSD; PDA with PR; Primum ASD;
coronary to RV fistula
Great Vessel
(RV to PA)
>5% PDA; AP window; Aberrant coronary
artery origin
Any level
(SVC to PA)
>7% All the above

18.  Generally done in two ways
1. The ratio of pulmonary blood flow versus the
systemic blood flow can be calculated (QP/QS)
2. Calculation of actual flow of the shunt by
difference between the pulmonary blood flow
and the systemic blood flow
 These two are equal in a normal heart

19. Quantification of shunt size using Qp/Qs is not affected
by hemoglobin concentration and the relationship
between Qp/Qs and shunt flow is linear

20.  If a PV has not been entered, systemic arterial oxygen
content may be used if >95%

21.  If systemic oxygen saturation is <95% then,
• Must determine whether a right to left intracardiac shunt
is present
• If right to left shunt is present then an assumed value for
pulmonary venous oxygen content of 98% oxygen
capacity should be used
• If no right to left intracardiac shunt is found, then the
observed systemic arterial oxygen saturation should be
used to calculate pulmonary blood flow

22. Oxygen consumption can measured by using the metabolic rate meter
Mixed venous oxygen content must be measured in the chamber
immediately proximal to the shunt

23. Location of shunt as determined
by site of O2 step-up
Mixed venous sample to use in
calculating systemic blood flow
1. Pulmonary artery (e.g., patent
ductus arteriosus)
Right ventricle
2. Right ventricle (e.g., ventricular
septal defect)
Right atrium
3. Right atrium (e.g., atrial septal
defect)
3 SVC + 1 IVC
4

25. These equations are simplified as
Since pulmonary veins are rarely entered during a cardiac cath,
a pulmonary catheter wedge sample or LA sample (if the LA is
entered via an ASD) can be used in its place
Alternatively, arterial saturation can be substituted or an
assumed value of 98% may be used

26.  Qp/Qs can be a very useful tool in making decisions
about the need for repair of a shunt
• Qp/Qs of 1–1.5 – observation is generally recommended.
• Qp/Qs ratio of 1.5–2.0 – significant enough that closure (either
surgically or percutaneously) should be considered if the risk of the
procedure is low
• Qp/Qs ratio of greater than 2 – closure (either surgically or
percutaneously) should be undertaken unless there are specific
contraindications

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

28.  Primary indication for the use of techniques to detect
and localize right to left intracardiac shunts is the
presence of cyanosis, or more commonly, arterial
hypoxemia
 Right to left shunting is unusual except in the case of
Eisenmenger syndrome
 Qp/Qs will be less than 1

29.  In right to left shunting, the effective pulmonary flow is
reduced by the amount of the shunt
Flow through the + Flow through the shunt = Flow through the
pulmonary valve aortic valve

30. 1. Angiography:
May demonstrate Right to Left intracardiac shunts
Important in detecting Right to Left shunting owing to
a pulmonary AVF
Although angiography may localize Right to Left
shunts, it does not permit quantification

31. 2. Oximetry :
The site of Right to Left shunts may be localized if blood
samples can be obtained from a pulmonary vein, LA, LV
and aorta
The pulmonary venous blood of patients with arterial
hypoxemia caused by an intracardiac Right to Left shunt is
fully saturated with oxygen
Site of a Right to Left shunt may be localized by noting
which left heart chamber is first to show desaturation (i.e.,
a step-down in oxygen concentration)

32. e.g., If LA blood oxygen saturation is normal but
desaturation is present in the LV and in the systemic
circulation, the Right to Left shunt is across a VSD

33.  The only disadvantage of this technique is that a
pulmonary vein and the left atrium must be entered
• This is not as easy in adults as it is in infants, in whom the left
atrium may be entered routinely by way of the foramen ovale

34.  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

35. Oxygen content = hemoglobin × 1.36 × percent saturation
The approximate left-to-right shunt then equals Qp - Qeff, and
the approximate right-to-left shunt equals Qs - Qeff

36.  Pulmonary circulation is characterized by high flow, low
pressure and low resistance system
 Normal pulmonary systolic pressures are 18-25 mm Hg, end
diastolic pressure ranges from 6-10 mm Hg and mean
pulmonary arterial pressures of 10-16 mm Hg
 Pulmonary hypertension is define as mean pulmonary
artery pressure (MPAP) >25 mm Hg at rest or > 30mmHg on
exercise or systolic pulmonary artery pressure >30 mm Hg
 Pulmonary artery pressure increase in response to increase
on LA pressures, pulmonary vascular resistance and cardiac
output

37.  The pulmonary vasculature is a dynamic system and is
subject to many mechanical, neural and biochemical
influences
 Pulmonary vascular resistance provides general
information about the pulmonary circulation but this
must be interpreted in the context of the clinical
situation and other hemodynamic data obtained during
cardiac catheterization

38.  Expressed in Woods unit (1WU=1mm Hg/L = 80
dynes/cm3
)
 Normal value is < 3 WU or 150 – 250 dynes/sec/cm3
 PVR is one sixth SVR

39.  Factors increases PVR
• Hypoxia
• Hypercapnia
• Increased sympathetic tone
• Polycythemia
• local release of serotonin
• Mechanical obstruction by multiple pulmonary emboli
• Precapillary pulmonary edema
• Lung compression (pleural effusion, increased
intrathoracic pressure via respirator)

40.  Factors that decreases PVR:
• Oxygen
• Adenosine
• Isoproterenol
• Inhaled nitric oxide
• Prostacyclin infusions
• High doses of calcium channel blockers

41.  Pulmonary vasoreactivity can be checked with the help
of
• 100% oxygen
• Adenosine
• Epoprostenol
• Inhaled nitric oxide

43.  Positive response is define as:
• 20% fall in pulmonary artery pressure and PVR or
decrease in mean pulmonary artery pressure of 10
mm Hg to an absolute value of less than 40 mm Hg
without in decrease in cardiac output
 These are the patient who are most benefited from
corrective procedure and calcium channels
blockers

44.  The ratio between pulmonary vascular resistance and
systemic vascular resistance (resistance ratio) can be
used as a criterion for operability in dealing with
congenital heart disease
• Normally, this ratio is <0.25
• Values of 0.25 to 0.50 indicate moderate pulmonary vascular
disease
• Values greater than 0.75 indicate severe pulmonary vascular
disease
• When the PVR/SVR resistance ratio equals 1.0 or more, surgical
correction of the congenital defect is considered
contraindicated because of the severity of the pulmonary
vascular disease

45. Q 1. What is the level of shunt?
Q 2. What is the direction of shunt?
Q 3. What is diagnosis?
Q 4. What is Qp/Qs

46. Q 1.What is the level of shunt?
Q 2.What is the direction of shunt?
Q 3.What is diagnosis?
Q 4.What is Qp/Qs?

47. Q 1. What is the level of shunt?
Q 2. What is the direction of shunt?
Q 3. What is diagnosis?
Q 4. What is Qp/Qs

48. Q 1.What is the level of shunt?
Q 2.What is the direction of shunt?
Q 3.What is diagnosis?
Q 4.What is Qp/Qs