Transcript File - Respiratory Therapy Files

Chapter 30
Congenital Heart Defects
•http://www.youtube.com/watch?
v=KRy8gfmGSxg
Cardiac Defects
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Patent Ductus Arteriosus
Atrial Septal Defect
Ventricular Septal Defect
Tetralogy of Fallot
Transposition of the Great Arteries
Coarctation of the Aorta
Anomalous Venous Return
Truncus Arteriosus
Hypoplastic Left-Heart Syndrome
Heart
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Congenital heart disease (CHD) occurs in 1/125
live births.
Neonates may present with a variety of nonspecific findings, including:
- tachypnea
- cyanosis
- pallor
- lethargy
- FTT
- sweating with feeds
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More specific findings include:
- pathological murmurs
- abnormal pulses
- hypertension
- syncope
Neonatal cardiac physiology
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The transformation from fetal to neonatal circulation involves two
major changes:
1. A marked increase in systemic resistance.
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caused by loss of the low-resistance placenta.
2. A marked decrease in pulmonary resistance.
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caused by pulmonary artery dilation with the neonate’s first
breaths.
•Fetal Circulation
•No circulation to lungs
•Foramen ovale
•Ductus arteriosum
•Circulation must go to placenta
•Umbilical aa., vv.
Fetal cardiac physiology
Fetal circulation:
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Blood flows from the placenta
 IVC
 RA
 through the PFO
 LA
 LV
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 ascending
aorta
 brain
 returns via
the SVC
Fetal cardiac physiology
Fetal circulation:
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From the SVC
 RA
 RV
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 pulm aa
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 through the
PDA
 descending
aorta
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 lower
extremities
and placenta
Fetal cardiac physiology
Fetal circulation:
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Only a very small amount of
blood is directed through the
right and left pulmonary aa’s
to the lungs.
Neonatal cardiac physiology
Neonate circulation:
• The transformation to neonatal
circulation occurs with the first few
breaths.
• The two remaining remnants of the
fetal circulation are a patent
foramen ovale...
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and ductus
arteriosus.
Congenital Heart Disease
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Neonates with CHD often rely on a patent ductus
arteriosus and/or foramen ovale to sustain life.
Unfortunately for these neonates, both of these
passages begins to close following birth.
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The ductus normally closes by 72hrs.
The foramen ovale normally closes by 3 months.
http://www.youtube.com/watch?v=FG-CNV501bc
CHD
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That being said, in the presence of hypoxia or acidosis
(generally present in ductus-dependent lesions), the
ductus may remain open for a longer period of time.
• As a result, these patients often present to the ED during
the first 1-3 weeks of life.
– i.e. as the ductus begins to close.
Classifying CHD
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There are many different classification systems for
CHD.
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None are particularly good.
I will be discussing the Pink/Blue/Grey-Baby
system:
1. Pink Baby – Left to right shunt
2. Blue Baby – Right to left shunt
3. Grey Baby – LV outflow tract
obstruction
Pink Baby (L  R shunt)
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L  R shunts cause CHF and pulmonary
hypertension.
This leads to RV enlargement, RV failure, and cor
pulmonale.
These babies present with CHF and respiratory
distress.
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They are not typically cyanotic.
http://www.youtube.com/watch?v=46tmI2_RVuE&list
=PLA81DD78BDE77FBFC
Pink Baby (L  R shunt)
• These lesions include (among others)
ASD’s, VSD’s, and persistently patent
ductus arteriosus.
•VSD
•ASD
Pink Baby (L  R shunt)
•Persistently
patent ductus
arteriosus
Pink Baby (L  R shunt)
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Diagnosing L  R shunts depends on:
1. Examination findings:
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Non-cyanotic infant in resp distress.
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Crackles, widely-fixed second heart sound, elevated JVP, cor
pulmonale.
2. CXR:
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Increased pulmonary vasculature (suggestive of CHF).
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RA and/or RV enlargement.
Pink Baby (L  R shunt)
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Initial management should be directed at
reducing the pulm edema.
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Adminster Lasix 1mg/kg IV.
Peds Cardiology/ PICU should be consulted
urgently regarding use of:
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Morphine
Nitrates
Digoxin
Inotropes
Ductus Arteriosus
• Fetal Circulation Component
– Connects Pulmonary Artery to Aorta
– Shunts blood away from lungs
– Maintained patent by presence of prostaglandins
• Closure secondary to:
– Increase in PaO2_
– Decrease in level of prostaglandins
Patent Ductus Arteriosus
• 5-10% of all births (1 of 2000 live births)
– 80% of premature babies
• 2-3 times more common in females than males.
• 5th or 6th most common congenital cardiac defect.
– Often associated with other defects.
– May be desirable with some defects.
• Morbidity/Mortality related to degree of blood
flow through PDA.
Pathophysiology - PDA
• With a drop in pulmonary arterial pressure
(reduction in hypoxic pulmonary vascular
constriction), blood will flow through PDA.
– LEFT TO RIGHT SHUNT
• Increased pulmonary blood flow may lead to
pulmonary edema.
– Reduced blood flow to all postductal organs
• NEC
• If pulmonary artery pressure rises above Aortic
pressure, blood will move in the other direction.
– RIGHT TO LEFT SHUNT
Diagnosis - PDA
• Loud grade I to grade III systolic murmur at
left sternal border.
– Washing machine
• Echocardiography
Treatment - PDA
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Restrict fluids.
Diuretics
Prostaglandin Inhibitors - Indomethacin
Surgical closure (ligation).
Atrial Septal Defect
• 6-10% of all births (1 of 1500 live births)
• 2 times more common in females than males.
• Types:
– Ostium Secundum (at or about the Foramen Ovale)
– Sinus Venous
– In 1950 most children with ASD did not reach the
first grade. Today, first year surgery facilitates
normal growth and development.
ASD: Pathophysiology and Diagnosis
• Pathophysiology
– Left to Right Shunt
• Inefficient recirculation of good blood through pulmonary
arteries.
– May not manifest symptoms and may be found later
in life.
– If defect is significant, may cause problems later in life
due to inefficiencies.
• Diagnosis
– Murmur
– Echocardiography
Treatment - ASD
• Surgical closure.
• Non-Surgical closure via cardiac catheterization.
Ventricular Septal Defect
• 1% of all births (2 to 4 of 1000 live births)
– Vast majority the hole is small.
• In 1950, fatal. Today almost all VSD can be
closed successfully, even in small babies.
Lillehei was the first person in history to
correct both ASD and VSD on 8/31/54.
VSD: Pathophysiology & Diagnosis
• Pathophysiology
– May be isolated or associated with other
congenital cardiac defects.
– With normal PVR:
• LEFT TO RIGHT SHUNT
– With elevated PVR (RDS):
• RIGHT TO LEFT SHUNT
• Diagnosis
– Echocardiography
Treatment - VSD
• Nothing if VSD is small.
• With CHF or Failure to Thrive: Surgical closure.
Blue Baby (R  L shunt)
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R  L shunts cause hypoxia and central cyanosis.
Neither hypoxia or cyanosis tend to improve with
100% oxygen.
R  L lesions include (among others):
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Tetralogy of Fallot (TOF)
Transposition of the Great Arteries (TGA)
Blue Baby (R  L shunt)
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Hypoxia and cyanosis (unresponsive to oxygen) in
the neonatal period suggests a ductus-dependent
lesion.
Treatment is a prostaglandin-E1 (PGE1) infusion.
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Dosing discussed momentarily
This should obviously be accompanied by urgent
Peds Cardiology and PICU consultation.
Tetralogy of Fallot
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Characterized by:
1. Pulmonary aa OTO
2. RV hypertrophy
3. VSD
4. Over-riding aorta
With severe pulmonary OTO...
bloodflow to the
lungs may be highly
ductus-dependent.
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Tetralogy of Fallot
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The classic CXR finding in TOF is
the boot-shaped heart.
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Pulmonary
vasculature is
typically decreased.
Tetralogy of Fallot
• 1% of neonates.
• Most common of the cyanotic cardiac diseases.
• Mortality increases with age (1 year-old has a 25%
mortality, 40 year-old has 95%).
• In 1950, fatal. Today, less than 5% mortality with
children operated on in infancy, leading normal lives.
Four Defects
– Pulmonary Artery Stenosis (determinant factor related to
severity)
– VSD (usually large)
– Overriding Aorta
– RV hypertrophy
Tetralogy of Fallot: Diagnosis and
Tet Spells (Blue spells) Treatment
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• CXR: Boot-shaped Heart
• Diagnosed with echocardiography.
• Surgical correction.
– Reparative or Palliative (Blalock-Taussig)
Blalock-Taussig
• Something the
Lord Made.
– Vivien
Thomas
Tetralogy of Fallot
Transposition of the Great Arteries
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TGA is one of the most common
cyanotic lesion presenting in the
first week of life.
Anatomically:
– RV  aorta
– LV  pulmonary aa
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To be compatible with
life, mixing of the two
circulations must
occur via an ASD,
VSD, or PDA.
•
http://www.youtube.com/watc
h?v=O83cYwKOKtI&list=PLA8
1DD78BDE77FBFC
Transposition of the Great Arteries
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The CXR findings in TGA are
typically less dramatic than in
TOF.
Pulmonary vasculature is
typically increased.
http://www.youtube.com/watch?v=bTkE_wygT4&list=PLA81DD78BDE77FBFC&index
=1
Complete Transposition of the Great
Arteries
• Second most common form (5-7%) of
congenital cardiac anomalies.
• Aorta arises from RV and Pulmonary Arteries
from LV.
• Without an abnormality, life would not be
possible.
– ASD
– VSD (30-40%)
– PDA
Transposition – Diagnosis and Treatment
• Diagnosis
– Chest X-Ray: “Egg on a String”
– Echocardiography
– Cardiac Catheterization (?)
• Treatment
– Balloon septostomy during
cardiac cath.
• Rashkind’s Procedure
• Reestablish Foramen Ovale
– Prostaglandin E1 to keep PDA
open.
– Surgical Correction
• Jantene Operation
Grey Baby (LVOTO)
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Left-ventricular outflow tract obstructions
(LVOTO’s) lead to cyanosis, acidosis, and shock
early in the neonatal period.
Complete obstruction is universally fatal unless
shunting occurs through an ASD, VSD, or PDA.
Examples of these lesions include:
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Severe coarctation of the aorta
Hypoplastic left heart syndrome (HLHS)
Grey Baby (LVOTO)
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Treatment:
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Any neonate presenting with shock unresponsive to
fluids +/- pressors has a LVOTO until proven
otherwise.
As with the Blue babies, appropriate management is
an urgent PGE1 infusion and emergent consultation.
Coarctation of the Aorta
• 7% of congenital cardiac defects.
• Constriction of the aorta.
– Results in severely reduced blood flow.
• Increased work on the heart leading to CHF
and cardiovascular collapse.
• Location of narrowing determines the clinical
signs.
• Usually associated with PDA, VSD and a
defective aortic valve.
•http://www.youtube.com/
watch?v=SiNJfvK_qeI
Location of Coarctation
• Pre-Ductal
– Less common but more serious
– Associated with VSD, PDA, Transposition
• Post-Ductal
– More common
– Often associated with collateral circulation beyond
coarctation, which minimizes effect.
– Diagnosed by a difference in blood pressure between
lower extremities and upper ones.
• Pressure in upper extremities > lower
Coarctation – Diagnosis and Treatment
• Diagnosis
– Chest X-Ray
– Echocardiography
– Cardiac catheterization
• Treatment
– Support with inotropic agents (Dopamine).
– Prostaglandins to maintain PDA.
– Surgical repair
–
http://www.youtube.com/watch?v=AGohu9fqKHg&list=PLF81322B9674D16CF
Anomalous Venous Return
• Return of pulmonary venous blood to the
right atrium instead of the left.
– ASD is present to sustain life.
– Can also be partial.
• Cyanosis usually present.
• Diagnosed with echocardiography.
• Surgical correction with reimplantation of
pulmonary veins.
Truncus Arteriosus
• Defect in which one large vessel arises from right and
left heart over a large VSD.
• Cyanosis is often present.
• CHF common.
• Diagnosed with echocardiography and cardiac
catheterization.
• Surgery:
– Separate pulmonary arteries from truncus.
– Closure of VSD
– Create valved connection between RV and Pulmonary
Artery
– http://www.youtube.com/watch?v=HXlWeSGIR7A
Repair of
Truncus
Arteriosus
Hypoplastic Left-Heart Syndrome
• Several anomalies:
– Coarctation of the aorta
– Hypoplastic left ventricle
– Aortic and mitral valve stenosis or atresia.
• Cyanotic defect.
• Right heart pumps blood to body through PDA.
• Closure of PDA results in hypotension, shock, and
death.
– Maintain hypoxemia with normalized CO2 levels.
• “40-40 Club”
http://www.youtube.com/watch?v=DcbiHP6zvus
1 Patent foramen
ovale
2 Coarctation of
the aorta
3 Patent ductus
arteriosus
4 Narrowed aorta
5 Hypoplastic left
ventricle
6 Aortic atresia
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Surgical Treatment of Hypoplastic Left Heart
Syndrome
• Three separate surgeries.
– Norwood procedure
• First few days after birth.
– Glenn Shunt (Cavo
Pulmonary Connection)
• 3-9 months of age
– Fontan Procedure
• 2 years of age
– Less wait because of damage
from pulmonary hypertension.
Stage I - Norwood Procedure
Stage II - Glenn Shunt
Stage III – Fontan Procedure
Prostaglandin-E1
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PGE1 promotes ductus arteriosus patency.
Use an IV infusion at 0.05-0.1 ug/kg/min.
A response should be seen within 15 min.
– If ineffective, try doubling the dose.
– If effective, try halving the dose.
The lowest possible dose should be used– as adverse-effects of
PGE1 can include:
- fever
- flushing
- diarrhea
- periodic apnea
(be ready to intubate)
Remnants of Fetal Circulation
• Ligamentum teres = Round ligament
– Remnant of the umbilical vein
– Anterior abdominal wall
• Ligamentum venosum
– Remnant of ductus venosum
– On liver’s inferior surface
• Medial Umbilical Ligaments
– Remnant of umbilical arteries
– Anterior abdominal wall below navel
– Also gives branch to urinary bladder
Clinical Monitoring
• Blood pressure
• Oxygen saturation
• End tidal carbon dioxide
Respiratory Care of Patients with Cardiac
Anomalies
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Vascular resistance
Ventilator management
Inhaled nitric oxide
Subambient oxygen
Hypercarbia