Download Congenital Cardiac Lesions

Congenital Cardiac Lesions
Overview
Three Shunts of Fetal Circulation
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Ductus Arteriosus
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Ductus Venosus
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Protects lungs against circulatory overload
Allows RV to strengthen
High pulmonary vascular resistance, low pulmonary
blood flow
Carries moderately saturated blood
Connects umbilical vein to IVC
Flow regulated via sphincter
Conducts highly oxygenated blood
Foramen Ovale
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Shunts highly oxygenated blood from RA to LA
Circulatory Changes at Birth
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Aeration of Lungs at Birth
Decreased pulmonary vascular resistance
secondary to lung expansion
 Increase in pulmonary blood flow- raising LA
pressure to higher than that of the IVC
 Thinning of walls of PA secondary to stretch
as lungs increase in size with first few breaths
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Changes Associated with
First Breath
Alveoli open
 Pressure in pulmonary tissues decrease
 Pressure in R. heart decreases
 Pressure in the L. heart increases as
blood returns from highly vascularized
pulmonary tissue to the LA
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Fate of the shunts…
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Foramen Ovale:
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Ductus Arteriosus:
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Closes at birth due to decreased flow from placenta and IVC
Pulmonary venous return causes pressure in LA to be higher
than that in RA
Due to decreased pulmonary vascular resistance, PA pressure
falls below systemic pressure and blood flow through DA is
diminished
Closure mediated by bradykinin
Prostaglandin E2 may reopen DA
Umbilical Vessels
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Constrict at birth and are then tied and cut
The Normal Heart
Right-Sided Heart Lesions
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Other right-sided cardiac abnormalities that
may present with or without cyanosis include:
 Pulmonary
Valve and Infundibular Stenosis
 Pulmonary Regurgitation
 Absence of the pulmonary valve
 Pulmonary Artery Stenosis
 Tricuspid Stenosis
 Double-chambered right ventricle
 Ebstiens anomaly
Ebsteins Anomaly
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Defect that mainly affects the tricuspid valve.
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Tricuspid valve may be malformed.
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The tricuspid valve is located lower than normal
The upper part of the right ventricle is part of the right atrium,
making the right ventricle is too small and the right atrium is too
large.
Abnormal leaflets may let blood leak back into the atrium after it
has flowed into the ventricle. The backward flow of blood makes
the atrium even larger and the ventricle even smaller.
Often Associated with other heart lesions
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ASD
Pulmonary Stenosis
Pulmonary Atresia
Treatment
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The mainstays of treatment for cyanotic heart
lesions are oxygen and prostaglandin.
PGE1 serves to reopen the ductus arteriosus or
prevent it from closing, which allows partially
desaturated blood to enter PA and be
oxygenated.
Initial dose of PGE1 is 0.1 mg/kg/min; can be
reduced to 0.02-0.05 mg/kg/min when patient is
stable.
Adverse Effects of PGE1 are rare, including
apnea, hypotension, edema, and fever.
Treatment- continued
General procedure for cyanotic heart
lesions involves a systemic to PA shunt.
 Procedure known as the Blalock-Taussig
shunt.
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Uses a small Gore-Tex® shunt to connect
either left or right subclavian to left or right
branch PA.
 Allows partially desaturated blood to enter PA,
increasing pulmonary blood flow and
oxygenation
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