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Pediatrics lect. 29+30 21-12-2009
Dr. Iyad AL-Ammouri
[ LECTURE OUTLINE ]
Fetal circulation
Congenital Heart Diseases
o Acyanotic HD
Left to Right Shunts
ASD VSD
PDA
Outflow Obstruction
Coarctation of the Aorta
Aortic Stenosis (not req'd)
Pulmonary Stenosis (not req'd)
Cyanosis
o Cyanotic HD
TOF TGV
Truncus Arteriosus
Tricuspid Atresia
TAPVR
[ INTRODUCTION ]
Congenital heart disease (CHD): heart defects that are present at birth
and cause problems for newborns. The American Heart Association statesthat there are at least 35 distinct forms of CHD, categorized into either
acyanotic or cyanotic lesions. However, before we discuss these diseases
we need to understand fetal circulation and circulatory changes that
occur at birth.
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Fetal circulation is different than newborn
circulation in many ways.
1) The cardiac output of the fetus is
considered "total cardiac output"(CO) or "combined ventricular
output" rather than the left
ventricular (LV) and right ventricular
(RV) output. This happens because the fetus does NOT use its lungs, as
they are full of fluid. Instead of going to the lungs, the blood is directed
across the patent ductus arteriosus to the descending aorta.
2) The organ responsible for oxygenation in fetus is the placenta (NOT lung)
3) 3 communications present in the fetal circulation that close after birth:
Communication Description FunctionPatent ductus
arteriosus
(PDA):
It is an
opening which
connects the
pulmonary
artery to the
aorta
It directs blood away from lungs because
they are not used. So most of blood going to
the pulmonary artery will cross PDA to aorta.
This means the direction of flow across the
PDA in the fetus is pulmon. a aorta
(NOT aorta pulmonary a. like newborn)
Patent foramen
ovale (PFO)
It is a
foramen
present
between theleft atrium
(LA) and the
right atrium
(RA)
It directs blood from the right side of the
circulation RA LA. This blood is rich in
oxygen because it comes mainly from the
inferior vena cava (IVC) and from theplacenta across the ductus venosus. In fact,
it is the most oxygenated blood in the fetus
(60-70% of blood is saturated), so it is
directed to the most important organs in the
body! Most of the blood crosses the PFO to
the LA LV ascend. aorta head & brain
Ductus venosus It is a communication between the umbilical vein (which
carries O2-rich blood from the placenta, O2saturation
70%) across the hepatic area into the IVC.
These 3 communications close after birth (they disappear),
and the circulation divides into 2 separate parts:
1) Pulmonary circulation:"blue" (deoxygenated or
cyanotic) blood going to the lungs
2) Systemic circulation:"red" (oxygenated) blood going
to the body and end organs
*Remember: CO in the newborn is LV output only & is no longer combined.
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Congenital heart defects can be classified into 2 types of lesions:
1) Shunt lesions: presence of a shunt (communication) between pulmonary
and systemic circulations (direction of shunt either right left or left
right). As a result, blood goes to the wrong circulation (the one that
it's NOT supposed to go to) and there is mixing of the red and blue blood.2) Non-shunt lesions: obstructive or regurgitant lesions (not topic of lect)
The shunt lesions are divided into 2 major categories:
1) Left to Right shunt
2) Right to Left shunt or "cyanotic heart disease"
Obstructive lesions Regurgitant lesions
congenital lesions
cause pressure load
Examples:
o *Aortic stenosis (AS)
most common
o Supravalvar AS
o Subaortic stenosis
o Coarctation of Aorta
o Mitral Stenosis
o Pulmonary Stenosis
acquired lesions
cause volume overload on heart
Examples:
o Aortic regurgitation
o Mitral regurgitation
o Tricuspid regurgitation
o Pulmonary regurgitation
*NOTE: physiology of obstructive
and regurgitant lesions is NOT req'd
*NOTE: most patients with cyanotic heart disease have R to L shunt, but they may
have a combined shunt (R to L & L to R) with complete mixing of blood in the heart.
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*REMEMBER:
Pulmonary blood flow: amount
of blood going to the lungs
Systemic blood flow:amountof blood going to the body
Left to Right Shunts------- Outflow Obstruction
There are 3 major types of L to R Shunts
1) ASD(atrial septal defect)
2) VSD(ventricular septal defect)3) PDA(patent ductus arteriosus)
In L to R shunts, the red blood crosses the area of the defect and goes to the
lungs. Whether the lesion is an ASD, VSD, or PDA, the blood goes across the
defect RA RV pulmonary artery lungs. This is an example of
"ineffective circulation"(amount of red blood going to the lungs = ineffective
pulmonary blood flow) because the blood is already 100% saturated and
canNOT become more red. It causes volume overload on the lungs, but there is
NO cyanosis because the systemic blood flow is still 100% saturated.
*NOTE: effective pulmon.blood flow: blue(cyanotic) blood going to lungs (what we need)
To measure the L to R shunt, we depend on the ratio between the pulmonary andsystemic blood flow (Q=blood flow). For example, if the ratio of Qp/Qs= 2:1
then the shunt is causing twice as much blood to pass through the lungs as what
is passing through the systemic arteries.
Physiologic effect of the shunt is dependent on 3 factors:
1) Location of the shunt
2) Size of the defect
3) Relative pulmonary and systemic vascular resistance (or ventricular
compliance in case of atrial level shunts)
FROMRO2IA
Large shunts cause the pulmonary blood flow to increase and can be associated later
with development of pulmonary arteriolar hypertrophy, increase in pulmonary
resistance and pulmonary hypertension. Over time the elevated pulmonary resistance
may force the direction of original shunt to reverse, causing R to L shunt and cyanosis.
The development of pulmonary vascular disease as result of chronic left to right shunt
is known as EISENMENGER Syndrome
ASD (v. imp)ASD is an atrial level shunt (persistent opening of interaterial septum after
birth that allows direct communication between the LA and
RA). The defect can occur anywhere along the septum and
produce different types of ASD that share the same
physiology (ex. secundum ASD, primum ASD NOT req'd).
VERY IMP: In CHD,
the heart will do what
it can to compensate
for and maintain CO.
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PhysiologyWe will focus on the physiology (v. imp) of ASD because it will help us
understand everything else heart changes, clinical signs and symptoms, and lab
findings. The CO in patients with ASD is normal, meaning the heart will pump
the same volume of blood to the body as a normal heart (normal CO= 3-5 L/min).
In the figure, the CO 4 L (volume of blood
leaving the heart) and the O2saturation = 100%.
It will return to the systemic veins as 4 L. Let's
assume that the ASD (between the LA and RA)
will allow another 4 L of blood to cross per minute
(from high pressure of LA to low pressure of RA).
So, we will have 8 L in the RA and RV. This volume
will go to the lungs and will come back to the LA
as 8L. Then it will be divided into 4 L across theASD and 4 L into the LV (which is the normal CO).
So at the equilibrium state, there is compensated
CO in patients with ASD. This means L to R shunt
does NOT compromise the systemic blood flow,
but it increases the pulmonary blood flow.
FROM RO2IA
In the RA 1/2 of blood is arterial with 100% O2sat. and 1/2 of blood is venous with
70% O2sat.. They will mix and the RV out put will be 8L blood with 85% O2saturation.
Based on the above, the following heart chambers undergo changes:1) LA dilation(it becomes bigger): because it is receiving 8 L of blood
instead of 4 L (twice the normal amount)
2) RA dilation
3) RV dilation
4) Pulmonary artery dilation
These areas are receiving more blood than usual, so they are subjected to
volume overload. Volume overload gives dilation in chambers and stenosis on
valves(tricuspid and pulmonary valves = stenotic due to chronic shunting and
volume overload). The majority of the shunt occurs during diastole(ventricular filling ventricular diastole = atrial systole)
The LV in patients with ASD is NOT affected, so there is NO LV dilation. This
means they will NOT develop signs of heart failure or decreased tissue
perfusion. They will NOT have any type of holosystolic murmur because the
flow across the ASD is at low pressure.
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Symptoms1) Usually there are NO symptoms (asymptomatic)
2) Some patients who present with FTT (failure to thrive) are incidentally
found to have ASD, but we should look for other causes of FTT because
ASD does NOT normally cause FTT.3) ASD aggravates symptoms of pulmonary diseases (ex. asthma, pneumonia,
etc) but does NOT cause them. So, children with underlying pulmon. dis.
may be more symptomatic with ASD due to increased pulmon. blood flow.
4) There is NO congestive heart failure (very rare)
5) Older children may complain of dyspnea on exertion only due to increased
pulmonary blood flow (asymptomatic at rest).
6) Pulmonary hypertension almost never happens in young patients with ASD
because it is a low pressure shunt (less than 10% risk)
7) Older patients may present with arrhythmias like SVT (supraventricular
tachy) or atrial/vent. tachy due to RA dilation.8) Paradoxical emboli may occur in older patients (rare in children).
FROM RO2IA: A paradoxical embolus is a venous embolus that bypasses the lung due to
R-L shunt through ASD, and becomes arterial embolus. It occurs with reversal of the
shunt in EISENMENGER syndrome.
Examination1) Normal in young infants
2) Prominent RV heave due to RV dilation
3) Wide, fixed split of S2 because the RV is pumping twice as much blood tothe lungs across the pulmon. valve. So, systole will occur over a longer
period of time and P2 will happen later than A2 of second heart sound.
4) Ejection systolic murmur of the pulmonary valve because there is more
blood across a normal valve (relative pulmonary stenosis)
5) Diastolic murmur (rumble) of the tricuspid valve (if the ASD is very large,
due to increased blood flow thru the tricuspid valve)
REMEMBER:
All findings and changes can be
explained byphysiology of ASD.
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DiagnosisECG:(beyond infancy - findings reflect the physiology)
1) Signs of right axis deviation
2) Signs of RA dilation or hypertrophy
3)Signs of RV increased mass (the ventricular mass is increased, NOTnecessarily hypertrophic)
4) Atrial arrhythmias +other things in specific types (not mentioned by dr
rSR pattern of incomplete right bundle branch block, peaked P waves in
lead II, sinus node dysfunction in sinus venosus defects,
northwest/superior QRS axis is typical of Primum ASD& AV canal defect)
CXR:
1) Normal (most of the time)
2) Dilated RA, RV & pulmonary artery: RA or right
border of the heart is dilated and extends more to
the right (NO shifting of apex beat)3) RV against sternum because it's dilated (lateral CXR)
4) Increased pulmonary blood flow (plethoric lungs)
5) Increased vascular markings (blood vessels are a
little larger than normal. The lungs are NOT opaque
and there is NO pulmon. edema. Actually, the lungs are
"plethoric" opp. of "oligemic lungs", which are more black)
6) Cardiomegaly (occasionally, because there is mainly RA
dilation NOT LV dilation)
Echocardiograph: Diagnostic method
Management1) The only method is closure of the defect, if it is indicated (by surgery or
by cathether details of devices used for closure NOT req'd)not mentioned by dr: Secundum ASD: transcatheter closure is
amenable in most cases. Sinus venosus, primum ASD and extremely large
or deficient rim secundum ASDs require surgical closure
2) NO medications should be given
3) NO need for subacute bacterial endocarditis (SBE) prophylaxis (not
mentioned by dr except in case of primum ASD because of theassociated mitral regurgitation)
4) NO restriction from activity
5) Spontaneous closure may occur in small or med. size secundum ASD
Dr. Zuhdi:There is increased risk of SBE because with time the shunt damages the
epithelium (breaks it down), which creates a good media for bacterial growth.
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VSDVSD is a communication between the LV and RV (ventricular level L to R shunt).
So we have red blood going to the RV. The types of VSD differ in terms of
management and prognosis, but they share the same physiology. VSD is
categorized into groups according to the site of the defect:
1) *Peri-membranous VSD(most common): co-ventricular defect around the
membranous part of the ventricular septum (remember that the
ventricular septum is mostly muscular, except for a small membranous
part underneath the aortic valve). There is incidence of aortic valve
prolapse and AI (aortic insufficiency)
2) Muscular VSD(2ndmost common): one or
more ms defects in any part of vent.
septum (anterior, apical, mid, posterior)
3) Inlet VSD or AV canal(more than aVSD): atrioventricular canal defect,
also known as "endocardial
cushion" defect. This defect is
associated with abnormal mitral and
tricuspid valves. Instead of
being 2 valves, they are actually 1
valve (common junction). Complete
AV canal is common in patients with
trisomy 21 or Down synd.)
4) Sub-pulmonary defect(conal septalhypoplasia) NOT req'd
Physiology
Remember the general rule: the heart will do whatever it canto make the CO normal. Again, we will assume that the CO
4 L min (same #s used in ex. for ASD). These 4 L will come
back to the RA RV, then another 4L it will cross the VSD
from LV to RV pulmonary arteryLALV. The ratio
between pulmon. blood flow and systemic blood flow (Qp: Qs)
is the same as that discussed above in ASD (2: 1, volume
overload), but the physio differs.
RV aspect of
vent. septumTricuspid
valve
Pulmonary
valve
RV
Aortic
valve
(inside)
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VERY IMPORTANT:
VSD systolic shunt
ASD diastolic shunt
Volume overload- dilation of
chambers & stenosis of valves
Pressure overload
hypertrophy of chambers
The chambers that will be affected in VSD:
1) LA dilationbecause it is receiving 8 L blood
2) LV dilationbecause it is receiving 8 L during
diastole (it fills with 8 L).
3) RV hypertrophydue to pressure load (there
is a hole between 2chambers, one pumping athigh resistance and the other pumping at low
resistance; so pressure will be transmitted to RV thru systole VSD
shunt is systolic. The RV will not be affected by any volume changes
because the pulmon. valve is open, so all of the 4L will go directly to lungs)
4) Pulmonary artery dilationbecause it is receiving more blood (like in ASD)
NO changes in RA (at least early on) and CO well maintained even in large VSDs
FROM RO2IA
The hemodynamic changes that occur in VSD depend on the size of defect and relative
resistance in pulmon. and systemic vasculature. In small VSD, the defect itself offersmore resistance to flow than pulmonary or systemic vasculature, thus the magnitude of
shunt depends on the hole. Conversely with larger defects, the volume of shunt
depends on systemic and pulmonary resistances. Remember that in the perinatal period
the pulmonary vascular resistance is approximately equal to the systemic resistance, so
minimal shunting occurs between the ventricles. However, after birth the pulmonary
resistance falls and the blood will be shunted to the right along the pressure gradient.
Symptoms
1) Newborns with VSD are usually well (asymptomatic, especially if smallVSD) because their pulmonary vascular resistance is high (right side of
heart receives all systemic venous return, including blood from placenta).
It takes about 4-8 wks for their pulmonary resistance to decrease to the
normal adult level. So, the L to R shunt is minimal in the newborn period.
FROM Illust.Text: With the first breaths the baby takes upon delivery, resistance to
pulmonary blood flow falls and the volume of blood flowing through the lungs increases
6-fold. This results in a rise in the LA pressure. Meanwhile, the volume of blood
returning to the RA falls as the placenta is excluded from the circulation. The change
in the pressure difference causes the flap of the valve of the foramen ovale to be
closed. The ductus arteriosus also normally closes within the first few hours or days).
2) Moderate to large VSD: LA/LV dilation due to increased pulmonary blood
flow. Unlike ASD, congestive heart failure may follow (according to the
Frank-Starling law, excessive dilation of the LV will cause it to lose its
contractility. So, there will be systolic
dysfunction, the patient will become
decompensated, and the CO will drop).
Dr. Zuhdi:
Large VSD > 50% aortic width
Small VSD = 1-3 mm
Moderate VSD = in between
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3) Symptoms of heart failure in infants or babies are different than those
seen in adults. Usually, infants with large VSD present with *respiratory
symptoms due to fluid accumulation in the lungs (v.imp) For example:
tachypnea, tachycardia, diaphoresis (sweating during feeding), decreased
or difficulty feeding, resp.distress, failure to gain wt, recurrent LRTI,etc
4) FTT, usually due to large VSD5) Compensated patients deteriorate rapidly with infection
FROM RO2IA:
Augmented pulmonary
circulation can cause
pulmonary vascular
diseases early in life. As
pulmonary resistance
increases the shunt may
reverse leading tohypoxemia & cyanosis
EISENMENGER'S
SYNDROME
Examination1) Newborns may NOT have heart murmur in the first day of life because
the pressure in both ventricles is almost equal (high pulmonary vascular
resistance). So, there is NO turbulence of blood across the VSD,
meaning NO murmur may be heard until about 4-8 wks of life (Dr. Zuhdi:
musical grade 2 ejection systolic murmur).
2) Displaced apex beat because the LV is dilated.
3) Hyperdynamic precordium with large, visible pulsations (Dr. Zuhdi)
4) Pansystolic (holosystolic) murmur is common after first day of life due to
blood flow across VSD. (Dr. Zuhdi: may be accompanied by palpable thrill)
5) Small muscular VSD may be associated with short systolic murmurs
(These murmurs are actually pansystolic, but we don't label them as such
because they stop before S2. This occurs because the defect is in the
muscular part of the ventricular septum; the VSD is initially open but
then closes upon itself during ventricular contraction. This is a good sign
because it means that the defect is getting smaller in size, so at onepoint the murmur will disappear).
6) Loud P2 of second heart sound (because there is pulmonary hypertension).
7) Diastolic rumble due to excessive flow across a normal mitral valve
(Dr. Zuhdi: diastolic murmur at the apex usually indicates a large VSD)
8) S3 gallop may be present in patients with heart failure.
9) Hepatomegaly due to liver congestion if patient develops right heart
failure (Dr. Zuhdi)
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DiagnosisECG:(beyond infancyonly helpful in dx. NL if small VSDDr. Zuhdi)
1) Signs of left axis deviation
2) Signs of LV hypertrophy (LV dilation is a more accurate description)
3)Signs of LA dilation4) Northwest (superior) axis in AV canal defects (not mentioned by dr)
*NOTE: ECG does NOT differentiate between hypertrophy and dilation (reflects
presence of ventricular mass in general)
Dr. Zuhdi:ECG in VSD changes with time. First, it shows signs of LV hypertrophy,
then signs of biventricular hypertrophy, and finally signs of RV hypertrophy depending
on which chambers are exposed to the highest blood load and pressure.
CXR:(NL if small VSD Dr. Zuhdi)
1) Increased pulmonary flow2) Increased vascular markings
3) Cardiomegaly (especially if large VSD)
Echocardiography(diagnostic): It diagnoses
presence and type of VSD, as well as its effect on
other cardiac structures.
Management
1)
Asymptomatic patients do NOT need any treatment (we just wait for theVSD to close spontaneously. Spontaneous closure is common in small and
moderate perimembranous and muscular defects
2) Symptomatic patients may need medications to alleviate symptoms
3) NO restriction from activity
4) NO SBE prophylaxis (according to the new guidelines). However, some
people still give SBE prophylaxis while others do NOT.
5) Surgical treatment is the standard treatment for symptomatic VSDs like
the AV canal type VSDs because they dont close spontaneously (details
NOT req'd). If Eisenmenger syndrome occurs, then surgery is
contraindicated (Dr. Zuhdi)6) Transcatheter closure of certain types of VSD has been done (not
mentioned by the dr)
Dr. Zuhdi:It is known that the most common CHD is VSD. However, recent studies
show that bicuspid aortic valve is now #1.
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Patent Ductus Arteriosus (PDA)PhysiologyPDA is a L to R shunt between
the aorta and pulmon. artery.
If we apply same #s used in
the above examples to PDA, we will
find that it is very similar to VSD.
It causes the same chamber
changes, but it differs in that it
also causes wide pulse pressure.
Symptoms(book & dr's slides)1) Usually present in first 2wks of life, when PDA starts to constrict
2) Signs and symptoms of decreased systemic perfusion3) Lethargy, and signs of CHF
4) Metabolic acidosis and shock develops quickly
5) Should be in the differential diagnosis of neonates with R/O sepsis
Examination1) Continuous murmur beneath
the left clavicle
2) Poor pulses collapsing or
bounding(wide pulse pressure)
3) Poor capillary refill4) May not detect radiofemoral
delay or BP gradient in
patients with COA
(coarctation of aorta)
5) Ejection systolic murmur may
indicate aortic stenosis
6) Tachycardia and gallop
7) Tachypnea
8) Hepatomegaly
DiagnosisECG: RV hypertrophy
Echocardiography: Final diagnosis
Management
CXR: (like VSD)
1) Cardiomegaly
2) Pulmonary edema
In infants with asymp. PDA, closure at about 1 yr of age is recommended to
abolish the lifelong risk of SBE.
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Coarctation of the Aorta
PhysiologyCoarctation is a non-shunt,
obstructive lesion (coarctation= constriction or pinching).
There is obstruction in the
distal part of aortic arch (just
distal to subclavian artery), which
will cause the heart to pump at a
higher pressure in order to perfuse
the lower extremities. Eventually,
there will be collateral blood flow across area of obstruction.
Symptoms1) Symptoms usually do not show at birth, they begin to emerge after 1 wk
2) Hypertension in the upper extremities (above the constriction)
3) Normal or low blood pressure in the lower extremities
Examination1) LV hypertrophy with dilation of apex beat.
2) Difference in blood pressure between upper and lower limbs (look above)
3) Normal or ejection systolic murmur between shoulder blades
DiagnosisECG: LV hypertrophy
CXR: 1) Usually normal
2) Rib notching from development of collaterals
ManagementA child with severe coarctation should have surgery in early childhood, after
which long-term follow up is necessary.
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Please note that info found inthis box is from the slides but not
mentioned by the doctor!
Cyanosis is a clinical sign where you have bluish discoloration of the
lips it happens when there is clinically significant amount of
deoxyhemoglobin , in order to see the cyanosis by your eyes theremust be 3-4 gm/dL of deoxyHb If the Hb in an individual is 15
needs 5 gm of deoxygenated Hb so the saturation should be less
than 70% in order too see cyanosis on the other hand desaturation is not a
clinical sign; cant be seen by your eyes but by the saturation that you measure ,
so not everyone who is hypoxic , will be cyanotic especially in children who
usually have Hb of 10 & need to 60% desaturated inn order to see the cyanosis.
Causes of cyanosis
In children the majority of causes are pulmonary causes , either
1. airway disease like pneumonia , asthma or foreign body due to preventing the
air from getting in or hypoventilation due to central causes.
2.intrapulmonary shunting; the blue blood passes to the red blood area.
Cardiac causes are always secondary to intracardiac shunting ; the blue blood
goes to the red blood area.
3. other rare causes.
Mechanisms of cardiac cyanosis1. Pure right to left shunt; so a portion of the blue blood going to the left
side of circulation, this what happened in a patient with Tetralogy Of
Fallot (TOF).
2. Mixing, meaning that blue blood & red blood are mixed together in a
chamber & then it is distributed to the lungs & body .
From Illustrated : Cyanosis in a newborn infant with respiratory distress (respiratory rate
>60 breaths/min) may be due to:
cardiac disorders - cyanotic congenital heart disease
respiratory disorders, e.g. surfactant deficiency, meconium aspiration, pulmonary
hypoplasia, etc.
persistent pulmonary hypertension of the newborn (PPHN) - failure of the pulmonary
vascular resistance to fall after birth
infection - septicaemia, group B streptococcus and other organisms
inborn error of metabolism - metabolic acidosis and shock
polycythaemia.
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=Note = the difference between them is that the 1stmechanism has only
rightleft shunt , while the 2ndone has rightleft & left right shunt
but still causes cyanotic heart disease.
3. The Recirculation; the whole red blood will go to the wrong side of
circulation ( to the pulmonary artery , & the whole blue blood will go tothe body. That happens in transposition; where the left ventricle is
pumping the blood into the lungs while the right ventricle is pumping to
the body. So the pulmonary arterial saturation is 100% , systemic arterial
saturation is 50%.
Approach to cyanotic baby
o detailed History; age at presentation can give you a hint about what the
pt has . ex. TGA may present in the 1
st
day of life, TOF appears in the 1
st
few months of life. Symptoms of presentation that might range from
pure cyanosis with no respiratory symptoms to heart failure symptoms
which is mostly respiratory symptoms; SOB, tachypnia, fever, FTT,
feeding problems
o physical examinationmight also help : - General Exam
-Vital signs - Lung exam - Cardiac exam.
o Testing ; many tests can be done to a cyanotic baby :
- Chest radiography
- Electrocardiogram non of the 3 is diagnostic of the lesion itself
- Hyperoxia test=Note= The only test that is diagnostic is Echocardiogram.
HYPEROXIA TESTvery important clinical test
- If the pt is cyanotic & you can overcome his cyanosis by giving him
O2 then more likely he has respiratory illness rather than a shunt.
If there is a shunt, means blue blood going to the body so it won't be corrected
by O2 .
- We give the pt 100% O2 for 15 min. then take arterial sample for ABG then
look at the partial pressure of O2 (PO2) .
PO2 is > 250 so more likely to be a pulmonary disease; overcome by O2
PO2 is < 150 so more likely to be a shunt ; cardiac
PO2 is 150-250 gray zone
=Note= if a pt has PO2 =150 the saturation is 100% so we dont depend on
saturation BUT depend on PO2
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CCYYAANNOOTTIICCHHEEAARRTTDDIISSEEAASSEESS55TTSSTetralogy Of Fallot ( the most common) = Rt-Lt shunt
Transposition Of Great Arteries = recirculation
Truncus Arteriosus = mixing
Tricuspid Atresia >> note it is Atresia not Tricuspid stenosis = mixing
Total Anomalous Pulmonary venous Return =mixing
=Note= some add 1P which is Pulmonary atresia that can comes alone.
TTEETTRRAALLOOGGYYOOFFFFAALLLLOOTT4 things
1.Pulmonary stenosis or right
ventricular outflow tract (RVOT)
obstruction.
2.VSD.
3.Overriding of aorta; looks like
arising from both RV & LV.(overridingmeans that it is deviated towards the rightside to ride over the VSD and the right
ventricle).
4.RV hypertrophy because VSD is
large so the RV has the same pressure as the LV.TOF is the most commoncyanotic heart disease & the 3rdmost common
congenital heart disease = 10% of CHD.
* In the extreme form there is complete pulmonary atresia (PA/VSD), 2% of
CHD.
There is no known etiology but it is more common in syndromes like Down
syndromepatients that usually have AV canal but may have TOF.
It might be seen in other syndromes but are not important to know.
* Not typically found with syndromes: De Lange, Goldenhar, Klippel-Feil
* TOF is seen with malformation assoc :VACTERL, CHARGE, Velo-cardio-facial.
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Key
TGA: Transpositoin of Great arteriesLA,RA: Lt & Rt Atrium
RV,LV : right & left ventricles
TOF : Tetralogy of FallotCO: cardiac output
ABG : Arterial Blood GasPDA : patent ductus arteriosusVSD : ventricular septal defect
SVC : superior vena cavaIVC : inferior vena cava
SVR: systemic vascular resistance
PVR: pulmonary vascular resistance
This Figureexplains everything , please concentrate & you will get the pictureeasily>> remember the 4 items of TOF
The cardiac output (CO) is well preserved, the
aortic outflow is about 4L/min so there is normalCO this 5 (in the figure) or 4L will come to the RA
then 2L will cross the ventricular septum & 3L will
go to the lungs, the reason why the RV is trying
to pump blood & there are 2 ways to go either
through the pulmonary artery or the VSD
(remember that there is obstruction near the
pulmonary valve "RVOT obstruction" so some
blood will go through VSD but if no obstruction,
all blood will go through pulmonary artery & not
only That, some blood from LV will pass VSD topulmonary artery , so what determines how much
blood crosses is actually THE RESISTANCEto the
flow, there is much resistance to the flow to the
pulmonary artery so some of the blood will cross the left side of the circulation
so we have Right Left shunt.
The 3 L goes to the lungs , will come back fully saturated 100% to the LV ,
3L"from lungs"(100%) + 2L"fromVSD"(50%) =5L"goes thro aorta"(80%), the
pt will be cyanotic because of Right Left shuntso the saturation might be
80% goes through aorta then will come back from body as 50% saturation in the
RV 2L to left & 3L up! Blood to LA will be 100% 3L(100%) +
2L(50%)=etc.
>> Now we will conclude the chambers affected in TOF>>
~ None of chambers will have volume overload so NO Cardiomegaly, normal size
of the heart.
~ Decreased pulmon. blood flow so in X-ray you
will see oligemic lungs or more black lungs.
~ RV Hypertrophy because VSD is large so the
pressure is transmitted from the LV to the RVso there might be RV heave & right axis
deviation.
=Note= to differentiate between:
- oligemic lungs : normal # of ribs + black lung
- Hyperinflated lungs : more ribs + black lung
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Physiology of TOF
Depends on 2 things:
1. large unrestrictive VSD( equal pressure in both sides) 2. pulmonary stenosis.
If the pt doesnt have pul. Stenosis so it is VSD so overriding of aorta doesnt
contribute to physiology & RV hypertrophy is just due to VSD.
Pulmonary stenosisdiffers from pt to another & it's progressive with time; at
1 month of age it is moderate , but at 6 months it is sever & more cyanotic with
time.
Flow depends on the difference between systemic & pulmonic outflow
resistance
From Ru2ia: Normally, PVR (pulmonary vascular resistance) is 1/10thof the systemic resistance(10 times lower), so in case of large VSD, 10 times the amount of blood will go tothe lungs compared to the body. This of course means an overload on thelungs' vascularity.
From Ru2ia: Exercise will rapidly drop the PaO2, how?? Decreased SVR Increased R->L shunt During exercise, the systemic vascular resistance (SVR) is
decreased, this means that instead of the RV pumping 3L to the lungs and 2L to body (through VSD), it willpump 1L to the lungs and 4L to body. This means less blood to the lungs less O2
Increased oxygen consumption decreased venous oxygen saturation (instead of 50%, u willhave 30% so when mixing with the 3L(100%) = less O2 sat).
>> Patients with TOF or other cyanotic heart dis. (whom are not treated) oftensuffer from :
With TOF, PVR is usually normal
Resistance to flow is related to the fixed and/or dynamicobstruction (or multiple levels of obstruction)
Symptoms depend on the relationship of SVR to this resistance
*If pulmonic obstruction is mildMinimal cyanosis
Good exercise tolerance*With increasing obstruction
Worsening cyanosis at rest
Higher risk of spellsPoor exercise tolerance*pH and PCO2 are normal at rest*PO2 will vary with degree of obstruction
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Hypercyanotic spell ( TET spells ) IMP
Mainly here we talk about SQUATTING; the pt squats when he
feels cyanotic (knee-chest position) it is seen in pts beyond age
of 1 year, they learn how to do this in periods when they haveexcessive/sever cyanosis which is life threatening.
Precipitated by activity or fright, BUT could be spontaneous.
Physiology of Squatting
Hypercyanosis happens because there is more RV outflow obstructions at
times when they become profoundly cyanotic, the mechanism is somewhere
around the obstruction; where they have hypovolemia if the pt slept all through
the night , fasting ;(SVR is low, and blood volume is low after sleep), he will
become agitated in the morning for any reason, he becomes tachycardiactachycardiawill impair ventricular filling ; because it happens at the expense of
DIASTOLE not systole so impairment in the RV filling so the obstruction to the
RVOT increases (becomes more profound) because of its dynamics just under
the valve, just like pts of
Hypertrophic obstructive cardiomyopathy>> they have less
volume in the ventricle so the obstruction becomes sever
when they stand up the murmur becomes louder because the
filling drops.
So the same thing with the RV because of depressed
/decreased RV filling there will be more obstruction to the
pulmonary outflowthe blood of right ventricle will cross
VSD to the LV so more Right to left shunt during those
times cyanosis feeling cyanotic will increase agitation
( ) more tachycardia So it becomes like a cycle: the
pt either dies or loses consciousness.
>> If he loses consciousnessless tachycardiamight regain consciousness.
Dr.Zuhdi: stress( hunger,trauma,..) might cause cyanotic spell , the pt becomes semiconscious , O2sat = 40-50% because of infundibular spasminc. Rt to Lt shunt
In the tt u can give propranolol to release the spasm, NaHCO3 bcoz of metabolic acidosis ( lacticacidosis) due to hypoxia & anaerobic glycolysis.
Treatment of Spells
Reverse elements of the cycle :
-- if cyanosed give O2 ; improves PO2 in the pulmonary venous blood
-- knee-chest position ,why?
::Summary::
Sleeping
stress
tachycardic
impaired RV
fillinginc. obstruxn
inc. R to L
shunt
cyanosis
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1.Because squatting will squeeze the liver so this will increase the venous return,
filling the RV ,decreasing the obstruction.
2. squatting kinks the femoral arteries so this increases the resistance in the
systemic circulation so blood would rather go to the lungs than the aorta
-- give Morphine to calm the pt down.
-- give fluids to open up RV to fill it.-- finally give systemic vasoconstrictor (phenylpherine) which works at the same
mechanism of kinking femoral artery; inc. SVR.
-- beta blockers if surgery is not available to prevent these events.
Symptoms of TOF
-Cyanosis.
-Periods of Squatting.
Dr. Zuhdi: 1. cyanosis at age 4-5 mo depends on severity of pul.StenosisWith age due to subvalvular, infundibular stenosis 2.clubbing 3.transient inc. in cyanosis 4.tachypnea.
From Ru2ia: Clinical features: Extreme variability of presentations
Related to degree of RVOT obstruction Consistency of symptoms relates to degree of shunting between right and left
Cyanosis might be present in the neonatal period, it is always present in patients with PA (pulmonaryatresia) or severe obstruction. If you listen to them you might not here a murmur, especially if the PDA islarge (the PDA would be the only route of blood to the lungs).
Cyanosis might be minimal if the obstruction is mild or not severe
Some patients would be asymptomatic but with a murmur. The murmur of TOF can't be missed as thepulmonary valve is right under the sternum and it is a loud murmur.
Cyanosis Typically appears after 1 month as the obstruction becomes more prominent (typically appears
between 6wks and 6 months in the unrepaired infant)
Parents complain from cyanosis of nail beds and mucous membranes May be present at rest or only with agitation/exercise
Persistent cyanosis in childhood and clubbing if not repaired
*Cyanosis will be accompanied by: Hyperpnea: Increased rate and depth of respirations Increased fussiness progressing to decreased level of consciousness Increasing acidosis, can be fatal
*Theories: Primary infundibular spasm (unlikely) Hyperpnea as a primary cause Circulating catecholamines
*Spells are an indication for need of surgical intervention
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Diagnostic studies
CXR >>
~ normal size BUT abnormal shape
(boot-shaped heart)
~Upturning of the apex~Concavity on the area of pulmonary artery.
Instead of convexity there is concavity
because the pulmonary artery is small.
~Lungs are oligemic.
EKG >>
~RV Hypertrophyis the characteristic
finding
~RA Dilatation ~Right axis deviation.Dr. Zuhdi: on examination you can hear Ejection
Systolic Murmur bcoz LV & RV both pump to aortaso heard sound asso. With pul. stenosis (inc. intensityinc. severity of pul.stenosis), PMI= pul. Area.
*Arrhythmias and ectopy are uncommon pre-operatively
*RAD - degree of axis deviation relates to severity of RVH
Medical management
Polycythemia
Most pts of TOF are polycythemic as a secondary mechanism to the Hypoxia.Hematocrit will be > 60% so might have symptoms of hyperviscosity syndrome.
* > 65% serious hyperviscosity risk - Neurologic sequelae
-Clotting abnormalities
* Consider phlebotomy pre-operatively
Infection
R->L shunt, direct route to body
Bacterial endocarditis
Brain abscessTET spells
As mentioned above & MSO4, surgery
Surgical management
1.VSD closure
http://images.google.com.sa/imgres?imgurl=http://www.clker.com/cliparts/b/8/d/a/12456405211563039613badaman_blue_boot.svg.med.png&imgrefurl=http://www.clker.com/clipart-28740.html&usg=__5GBSccXfDBUTvc9MgNMPFVm4czA=&h=255&w=300&sz=37&hl=ar&start=14&um=1&itbs=1&tbnid=FKgzvJ9MTV30BM:&tbnh=99&tbnw=116&prev=/images%3Fq%3Dboot%2Bclipart%26hl%3Dar%26safe%3Dactive%26rlz%3D1T4SKPB_enJO319JO320%26sa%3DN%26um%3D17/25/2019 Cyanotic and Acyonitic Heart Diseases
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transatrial access if possible
Infundibular resection for visualization
Patch closure
2.Alleviation of RVOT obstruction done by surgery.
Infundibular resection vs. transannular patch
TRANSPOSITION OF GREAT ARTERIES (TGA)
~The pulmonary artery coming from the LV while the aortic artery fromRVso
blue blood will go to the same area & the red blood to the same area.
~We should have some mixing in order for pt to
survive ; because he won't survive more than few minutes if no communication .
~The communication has to be at the atria level(PFO or ASD) BUT if they dont have we should create it.
~ 50 % of pts have VSD; usually small, not contributing to the physiology.
~ usually presents in the 1st day/hrs of life with cyanosis so we dont think of
TOF although it's the most common.
~ More common in boys.
Diagnosis
If left untreated then the CXR finding will be
prominent.
-Egg on side - Narrow mediastinum;
because pul. Artery & aorta are front & back
NOT side by side.
=Note= you can't find that in the newborn period
but later on.
Physiology
The pt presents with profound cyanosis at birth; we should do number of things
medically before he goes to surgery; one is to insure there is mixingat atrial
level & to insure that blue blood is going to lungsso what we do is to keep PDA
open because it will allow blood to go from aorta to pulmonary arterywhich is blue
as it comes from Aorta that is connected to RV.
http://images.google.com.sa/imgres?imgurl=http://kalaalog.com/wp-content/uploads/2008/04/egg-large.png&imgrefurl=http://kalaalog.com/2008/04/03/egg-free-clipart/&usg=__Y0FkQRm73h7or_pKRaUigk26X5w=&h=502&w=400&sz=38&hl=ar&start=20&um=1&itbs=1&tbnid=kzMpuDiddHD3ZM:&tbnh=130&tbnw=104&prev=/images%3Fq%3Degg%2Bclioart%26ndsp%3D18%26hl%3Dar%26safe%3Dactive%26rlz%3D1T4SKPB_enJO319JO320%26sa%3DN%26start%3D18%26um%3D17/25/2019 Cyanotic and Acyonitic Heart Diseases
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* Examis significant for Single S2
Ejection click of the abnormal truncal valve Systolic murmur of truncal valve stenosis if present Diaastolic murmur of truncal valve insufficiency
Gallop* CXR: Cardiomegally , increased pulmonary circulation
* Management: basically the management is surgery like TOF, so we close the VSDand separate the Aorta and the Pulmonary artery.
TTRRUUNNCCUUSSAARRTTEERRIIOOSSUUSS
Is a common trunk arising from both
ventricles so it implies that there isVSD. There is no truncus without VSD
but we dont call it VSD or truncus-VSD.
This common trunk is divided into the
pulmonary artery & the Aorta , it
differs from the others because the
red & the blue blood are mixed
together .
It will be divided into 2 circulations
both have the same color ; same O2 saturation so it's complete mixing.
Then the blood will pass according to the resistance ; pulmonary vascularresistance (PVR) is very low (large way) BUT the systemic vascular resistance is
very high (small way) so more blood to the lungs.
Pts of TA won't present with cyanosis BUT they will present with Heart
Failure!! .why?Because there is more blood to the lungs; the ratio between pul. & systemic
blood flow is more than (5 : 1) so there will be dilation of the LA & LV &
symptoms of Heart failure .
with time they become cyanotic because of PVR rising as in Pulmonary
Hypertension.
Although it is called cyanotic heart disease BUT it causes Heart Failure
(tachypnea, hepatomegaly, FTT).
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TRICUSPID ATRESIA
Atresiameans The valve didnt form so NO
communication between RA & RV.
They have to have atrial communication.We have 2 options : either we will have VSD
because blood in the RA will mix with the blood in
the LA complete mixing so you can see it purple in
color in the figure . blood going to the lungs can
come from 2 options either VSD to the pul. Artery
or across Patent Ductus Arteriosus (PDA) to pul.
Artery .
Symptoms will depend on the amount of Pul. Blood
Flow ;
if VSD is small there will be cyanosisif VSD is large there will be Heart Failure because more blood flow to the
lungs than the body, so the cyanosis will be minimal .
=Note= So both Tricuspid Atresia + Truncus Arteriosus will have HFsymptoms.
TOTAL ANOMALOUS PULMONARY VENOUS RETURN (TAPVR)
It is the rarest cyanotic heart disease.
Instead of pulmonary veins coming to LA , they miss the LA but will come to RA
through a communication either through an abnormal vein ( vertical vein ordirectly to RA so the pul.veins which have red blood is coming to the SVC to RA
or to INC to RA so all the blood will be mixed in the RA (complete mixing), the
blood can't go to the LV except through ASD or
PDA.
The blood will be distributed to both circulations
through ASD & the pt is cyanotic.
Types of (TAPVR)
>> Supracardiac through the SVC
-Figure above-
>> Infracardiacthrough the IVC
-figure below-
>> Mixed type.From Ru2ia:In a radiograph of a Pt with supracardiacTAPVR, you will see a dilated superior vena cava, and it wouldshow a characteristic figure 8 shape.While in the infracardia type you would see pulmonary edemawithout cardiomegally, unlike in CHF where the heart would belarge.
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~ SLIDES NOT MENTIONED BY THE DOCTOR ~
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Done by Ruba Al-Abwah & We'am Al-Zayadneh
www.shifa2006.com
REFERENCES:Lecture recording
Ro2ia lecture
Illustrated Textbook of Pediatrics
Dr. Zuhdi Al-Hanuti (Al-Mafraq Hospital)
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