Cyanotic Congenital Heart Disease
د.اثل اطفالCyanotic CHD occurs when some of the systemic venous return crosses from the right side of the heart to the left and returns to the body without going through the lungs (right-to-left shunt).
Cyanosis, the visible sign of this shunt, occurs when approximately 5 g/100 mL of reduced hemoglobin is present in systemic blood.
The most common cyanotic congenital heart defects are the 5 Ts:
Tetralogy of Fallot
Tricuspid atresia
Transposition of the great arteries
Truncus arteriosus
Total anomalous pulmonary venous return
TETRALOGY OF FALLOT
TOF is the most common cyanotic congenital heart defect, representing about 10% of all congenital heart defects.
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Hemodynamics Pulmonary stenosis plus hypertrophy of subpulmonic or infundibular muscle (crista supraventricularis) lead to:
Varying degrees of right ventricular outflow obstruction
Blood shunted right-to-left across the VSD with varying degrees of arterial desaturation and cyanosis.
Clinical Manifestations The degree of cyanosis depends on the amount of pulmonary stenosis.
Infants initially may be acyanotic & ejection systolic murmur of PS is the usual initial abnormal finding.
If the pulmonary stenosis is more severe, or as it becomes more severe over time, the amount of right-to-left shunting at the VSD increases and the patient becomes more cyanotic later in the 1st yr of life & the murmur of PS becomes shorter and softer. May heard holosystolic murmer toward the lower sternal border.
In infants with severe degrees of PS, pulmonary blood flow may be partially or nearly totally dependent on flow through the ductus arteriosus. When the ductus begins to close in the 1st few hr or days of life, severe cyanosis and circulatory collapse circulation may occur.
Single S2 and right ventricular impulse at the left sternal border are typical findings.
Continuous murmur may be audible, especially if prominent collaterals are present.
Older children with long-standing cyanosis who have not undergone surgery may have:
Dusky blue skin, gray sclerae with engorged blood vessels.
Marked clubbing of the fingers and toes.Dyspnea occurs on exertion. They may play actively for a short time and then sit or lie down. Characteristically, children assume a squatting position for the relief of dyspnea caused by physical effort; the child is usually able to resume physical activity after a few minutes of squatting. These findings occur most often in patients with significant cyanosis at rest.
Paroxysmal hypercyanotic attack (hypoxic, blue, or tet spells)
It is a problem during the 1st 2 yr of life, the spells occur most frequently in the morning on initially awakening or after episodes of vigorous crying. The onset is usually spontaneous and unpredictableThe infant presented with:
restless
cyanosis increases
ambulatory toddler may squat
gasping respirations ensue, and syncope may follow.
Temporary disappearance or a decrease in intensity of the systolic murmer.
The spells may last from a few minutes to a few hours.
Short episodes are followed by generalized weakness and sleep.
Severe & prolonged spells results in severe systemic hypoxia and metabolic acidosis. may progress to unconsciousness and, occasionally, to convulsions or hemiparesis.
Treatment of spells:
Depending on the frequency and severity of hypercyanotic attacks, 1 or more of the following procedures should be instituted in sequence:
Placement of the infant on the abdomen in the knee-chest position or squatting in older children (increases the peripheral vascular resistance, which diminishes the right-to-left shunt & increases pulmonary blood flow).
O2.
Morphine s.c. (max 0.2 mg/kg).
IV sodium bicarbonate if acidosis.
If spells are resistant to this therapy, intubation and sedation.
Drugs that increase systemic vascular resistance, such as IV phenylephrine, can improve right ventricular outflow, decrease the right-to-left shunt, and improve the symptoms. IV β- blocker as propranolol (0.1 mg/kg given slowly to a maximum of 0.2 mg/kg) to relax the infundibular.
Investigation:
ECG: RAD & RVH.
CXR: boot heart.
Echo: shows the anatomic features.
Complication:
Each anoxic spell is potentially fatal.
Polycythemia may lead to Cerebrovascular thrombosis (most often in patients younger than 2 yr.)
Brain Abcess (usually in patients older than 2 yr)
Anoxic infarction of CNS
Infective endocarditis
HF in some young infants with pink or acyanotic tetralogy of Fallot.
Treatment of hypoxic spells.
Neonates with marked PS given prostaglandin E1 (0.01-0.20 μg/kg/min), to maintain ductal patency and usually provides adequate pulmonary blood flow until a surgical procedure can be performed.
Complete surgical repair with VSD closure and removal or patching of the pulmonary stenosis can be performed in infancy.
Palliative shunt surgery (Blalock-Taussig shunts), anastmosis between the subclavian artery and pulmonary artery is performed for complex forms of tetralogy of Fallot and more complete repair is done at a later time.
Subacute bacterial endocarditis prophylaxis .
TRICUSPID ATRESIA
Tricuspid atresia accounts for approximately 2% of all CHD.
The absence of the tricuspid valve results in a hypoplastic right ventricle.
All systemic venous return must cross the atrial septum into the left atrium.
A PDA or VSD is necessary for pulmonary blood flow and survival.
Clinical Manifestations
Severe cyanosis.Single S2
If a VSD is present, there may be a murmur.
A diastolic murmur across the mitral valve may be audible. Frequently there is no significant murmur.
Investigation:
ECG: LVH & LAD.
CXR:
normal or mildly enlarged cardiac silhouette.
decreased pulmonary blood flow.
Echo: shows the anatomy, associated lesions, and source of pulmonary blood flow.
Treatment: If there is no VSD, or it is small, prostaglandin E1 maintains pulmonary blood flow until surgery.
Palliative procedure: Blalock-Taussig procedure.
Definitive: two stages procedure bidirectional cavopulmonary shunt (bidirectional Glenn) and Fontan procedure.
A/ Bidirectional Glenn shunt showing the superior vena cavaright pulmonary anastomosis.
B/ Modified Fontan procedure (cavopulmonary isolation) involves anastmosing of inferior vena cava to pulmonary artery.
Ebstein Anomaly of the Tricuspid Valve
Downward displacement of abnormal tricuspid valve into right ventricle; the right ventricle gets divided into two parts:
Atrialized portion, which is thin-walled.
Smaller normal ventricular myocardium.
Right atrium is huge; tricuspid valve regurgitant.
Right ventricular output is decreased because:
Poorly functioning, small right ventricle.
Tricuspid regurgitation.
Variable right ventricular outflow obstruction produced by large, sail-like, anterior tricuspid valve leaflet. Therefore, increased right atrial volume shunts blood through foramen Ovale or ASD → cyanosis.
Clinical Manifestation:
The severity of symptoms depend on the:
extent of displacement of the TV .
severity of RV outflow tract obstruction.
Symptoms may be mild and may be delayed until the teenage years or young adult life.
Newborns with severe forms of Ebstein anomaly have:
marked cyanosis.massive cardiomegaly.
long holosystolic murmurs of TR audible over most of the anterior left side of the chest.
Investigation:
CXR: heart size varies from slightly enlarged to massive box shaped cardiomegaly caused by enlargement of the right atrium.
ECG:
RBBB.
Tall and broad P waves.
Normal or prolonged P-R interval.
SVT may occur.
Echo: shows the anatomy.
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Cardiomegaly in Ebstein anomaly
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Treatment:
PGE1
Systemic-to-pulmonary shunt
Then staged surgery
Cyanotic CHD with Increase PBF
TRANSPOSITION OF THE GREAT ARTERIESAlthough TGA represents only about 5% of CHD, it is the most common cyanotic lesion to present in the newborn period.
Aorta originating from the right ventricle, and pulmonary artery originating from the left ventricle.
Survival is dependent on the presence of mixing between the pulmonary and systemic circulation. Associated ASD, VSD, or PDA are essential for survival . 50% of patients have a VSD .
Usually presents in the first day of life with profound cyanosis.
More common in boys
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Clinical Manifestations A history of cyanosis is always present, although it depends on the amount of mixing.
Tachypnea.
Single S2 are typically present, but may be split.
If the ventricular septum is intact, there may be no murmur.
Children with large VSD have improved intracardiac mixing and less cyanosis. They may present with signs of heart failure. The heart is hyperdynamic, with palpable left and right ventricular impulses. A loud VSD murmur is heard. S2 is single.
Investigations:
CXR : Egg on a string & narrow mediastinum
Echo: shows the TGA, the sites and amount of mixing, and any associated lesions.
Treatment:
Initial medical management includes prostaglandin E1 to maintain ductal patency.If significant hypoxia persists on prostaglandin therapy, a balloon atrial septostomy improves mixing between the two circulations.
Complete surgical repair is most often an arterial switch. The arterial switch usually is performed within the first 2 weeks of life.