Congenital Heart Disease

Last Updated on by frcemuser

Congenital heart disease is the most common of all congenital malformations, affecting 9 in every 1000 newborns. Screening for congenital heart disease includes ultrasonography in the second trimester of pregnancy and postnatal clinical examination; however, detection rates are low and patients may still present undiagnosed to ED. Presentations range from life threatening shock or cyanosis in a neonate to respiratory distress, congestive cardiac failure and failure to thrive in infants. As 80-85% of patients with CHD now survive to adulthood, patients can also present later in life with complex needs.

Shock and the collapsed baby

CHD lesions presenting as shock:

  • Coarctation of the aorta
    • Pathophysiology:
      • Significant narrowing in thoracic aorta just distal to the left subclavian artery near the region of the ductus arteriosus (can be pre-ductal, ductal or post-ductal). Vessels to the head and upper limbs emerge proximal to the narrowing so blood supply to these areas isn’t compromised but blood flow to the rest of the body is often reduced. Coarctation causes increased afterload on the left ventricle which can cause hypertrophy.
    • Clinical features:
      • Absent femoral pulses or radio-femoral delay before DA closes
      • Cyanosis
      • Four limb BP discrepancies – gradient of > 10 mmHg is clinically significant
      • Signs of CCF
    • Diagnosis:
      • Diagnosis is usually made antenatally via USS scan
      • ECG may show LVH or RV conduction delay
      • CXR: may show figure of 3 sign (formed by pre-stenotic dilation of the aortic arch, site of coarctation, and post-stenotic dilation)
      • All patients should have either cardiac MRI or CT for evaluation of thoracic aorta prior to definitive management
    • Management:
      • Rapid A-E assessment of collapsed neonate
      • Prostaglandin infusion if duct-dependent circulation
      • Diuretics to reduce preload combined with volume replacement to correct metabolic acidosis
      • Surgery usually performed within 24 hours – removal of the narrow segment
  • Hypoplastic left heart syndrome
    • Pathophysiology:
      • The lesion causes severe mitral and aortic valve stenosis or atresia. This is associated with an underdeveloped left ventricle, ascending aorta and aortic arch – often too small to sustain cardiac output. An ASD is also necessary to allow the pulmonary venous blood flow from the left atrium to the left atrium. A PDA is necessary to allow blood flow from the pulmonary artery to the systemic circulation – shock occurs when the PD closes.
    • Clinical features:
      • Increased right→left shunting leads to cyanosis, congestive heart failure, shock and respiratory distress
      • Absent femoral and brachial pulses, delayed CRT, hypotension secondary to shock
      • Signs of right heart failure – enlarged liver, tachypnoea, rales
      • Shock and respiratory distress secondary to acidosis upon DA closure
      • May have PDA murmur
    • Diagnosis:
      • Usually diagnosed prenatally
      • ECG: absent LV forces
      • CXR: cardiomegaly
      • Echo is gold standard for diagnosis
    • Management:
      • Patients should be born in a cardiac centre
      • Prostaglandin infusion to maintain DA patency
      • Surgery within 3-5 days – surgical management is staged and requires 3 operations to establish a single ventricle circulation

Differentials of circulatory collapse in the neonate (THE MISFITS):

  • Trauma and NAI
  • Heart disease
  • Endocrine disturbances
  • Metabolic/electrolyte disturbances
  • Inborn errors of metabolism
  • Seizures/CNS abnormalities
  • Formula errors
  • Intestinal disorders e.g. intussusception
  • Toxins
  • Sepsis

Cyanosis and the blue baby

CHD lesions presenting as cyanosis:

  • Truncus arteriosus
    • Pathophysiology:
      • When this occurs, the only artery arising from the heart is the truncus arteriosus that functions as both the aorta and pulmonary artery. Cyanosis occurs as there is mixing of deoxygenated and oxygenated blood. There is a single semilunar valve. The lesion is often associated with a VSD which sits under the semilunar valve. As pulmonary vascular resistance falls after birth, more and more blood travels into the low-resistance pulmonary circuit and heart failure develops.
    • Clinical features:
      • Cyanosis and heart failure
      • Wide pulse pressure
      • Systolic ejection murmur – increased flow across semilunar valve
      • Single second heart sound
    • Management:
      • Surgical repair via a Rastelli procedure. This involves a patch to close the VSD and allow the LV to communicate with the common trunk. A Conduit is then made from the RV to the pulmonary artery.
  • Transposition of the great arteries
    • Pathophysiology:
      • This occurs due to failure of separation of the pulmonary artery and aorta. The aorta is connected to the right ventricle and the pulmonary artery is connected to the left ventricle. This results in two parallel circulations where deoxygenated blood is pumped around the body and oxygenated blood circles around the lungs. Unless there is mixing of these parallel circulations e.g. via a VSD/ASD/PDA, severe cyanosis, metabolic acidosis and death will occur. Shunting of blood through either a VSD/ASD/PDA allows deoxygenated and oxygenated blood to mix before being pumped to the lungs and the body.
    • Clinical features:
      • Cyanosis
    •  Diagnosis:
      • ECG – usually normal
      • CXR: may show egg on string appearance or signs of CCF
    • Management:
      • Where there is no VSD, when the ductus arteriosus closes → cyanosis → ABCDE, prostaglandin infusion.
      • If there is a VSD, patients are usually well oxygenated however they are more prone to developing CCF so require surgical repair within the first few weeks.
      • Some infants with TGA and an intact ventricular septum will remain excessively cyanotic despite initiation of prostaglandin infusion and these patients require a balloon atrial septostomy to create an ASD.
      • The definitive management is an arterial switch operation. This is often carried out in the first few weeks to avoid left ventricular deconditioning.
  • Tricuspid atresia
    • Pathophysiology:
      • Lack of development of the tricuspid valve leads to poor inlet to the right ventricle. The resulting right ventricle is small and underdeveloped and there is often a degree of pulmonary stenosis. This causes right-to-left shunting as systemic venous return enters the right atrium, is shunted through the foramen ovale to the left atrium, left ventricle and aorta. Variable amounts of systemic return gains access to the pulmonary artery through a VSD. Flow to the pulmonary artery is therefore limited by the size of the ventricular defect and the amount of pulmonary stenosis.
    • Clinical features:
      • Cyanosis
      • Harsh systolic murmur
    • Diagnosis:
      • ECG: superior axis, absent RV voltages, large P-waves
        CXR: May have increased or decreased pulmonary vascular markings
    • Management:
      • If the lesion presents with cyanosis →BT shunt or RV to pulmonary artery conduit shortly after birth
      • If it presents with CCF, medical management is used initially followed by surgical correction with a pulmonary artery band to reduce pulmonary vascular resistance and pressure.
      • Definitive management is to establish Fontan circulation by 3-5 years of age
  • Tetralogy of Fallot
    • Pathophysiology:
      • Consists of 4 lesions which occur together as a result of a single developmental defect:
        • Ventricular septal defect
        • Overriding aorta
        • Pulmonary stenosis
        • Resultant right ventricular hypertrophy
      • Pulmonary stenosis and RV hypertrophy causes right to left shunting through an often too large VSD. The overriding aorta sits over the VSD therefore the mixed blood is then pumped to the body.  TOF presentation depends on degree of RV outflow obstruction as this determines the extent of mixing of oxygenated and deoxygenated blood.
    • Clinical features:
      • If there is a large degree of pulmonary stenosis the entire right ventricle output passes through the VSD. Pulmonary flow is only supplied by the DA → presents with cyanosis when the DA closes
      • If there less pulmonary stenosis, pulmonary blood flow will be higher → CCF and cyanosis later in life (hypercyanotic “tet spells”)
    • Diagnosis:
      • ECG: RA and RV enlargement
      • CXR: boot shaped heart due to RA and RV enlargement resulting in an upturned apex with an absent or diminished pulmonary artery
      • Echo/cardiac MRI +/- cardiac catheterisation – gold standard for diagnosis
    • Management:
      • 10% require BT shunt or RV to pulmonary artery conduit in newborn if severely cyanosed
      • Acute cyanosis at birth is managed with prostaglandins
      • Most have elective surgical repair at 6-9 months. This involves using a patch to close the VSD and surgical widening of the stenosed pulmonary valve.
  • Total anomalous pulmonary venous return
    • Pathophysiology:
      • When this occurs, the four pulmonary veins do not drain into the left atrium but drain into the innominate vein(Supracardiac), liver (Infracardiac ) or coronary sinus/right atrium (cardiac).
    • Clinical features:
      • Depends on the degree of obstruction between pulmonary veins and right heart
      • In Supracardiac and Infracardiac lesions, there is usually a higher degree of obstruction which presents at birth with pulmonary oedema, pulmonary hypertension and cyanosis →collapsed cyanotic neonate
      • In cardiac lesions there is less obstruction → Develop symptoms within weeks to months – mild cyanosis and CCF
    • Diagnosis:
      • ECG: Right axis deviation, RVH
      • CXR: snowman sign
      • Definitive imaging: Echo, cardiac MRI, angiography
    • Management:
      • If patients present obstructed – emergency surgical correction
      • If non obstructed – medical management of CCF (see section on the breathless baby) followed by elective surgical repair

Differentials of cyanosis in the neonate:

  • Respiratory
    • Persistent pulmonary hypertension
    • Acute respiratory distress syndrome
    • Pulmonary hypoplasia
  • Cardiac
    • Congenital heart disease
  • CNS
    • Seizures
    • Toxins
    • Intracerebral ischaemia
    • Intracerebral haemorrhage
  • Sepsis

Congestive heart failure and the breathless baby

Features of CCF in neonates:

  • Symptoms
    • Feeding difficulty
    • Sweating/tachypnoea with feeds
    • Failure to thrive
    • Respiratory distress
    • Fussiness
  • Signs
    • Tachypnoea and laboured breathing
    • Rales
    • Hepatomegaly
    • Cyanosis if severe
    • Faltering growth
    • Displaced apex beat
    • Cool peripheries
    • Gallop rhythm

CHD lesions presenting as congestive heart failure:

  • Ventricular septal defect
    • Pathophysiology:
      • Left-to-right shunt
    • Clinical features:
      • They are usually asymptomatic and undetectable unless large.
      • Large lesions are defined as being the same size or larger than the aortic valve and larger lesions are often associated with pulmonary hypertension and present with CCF after one week.
      • May have pansystolic murmur at lower left sternal edge – usually the louder the murmur the smaller the hole.
    • Diagnosis:
      • ECG: Biventricular hypertrophy by 2 months
      • CXR: shows increased pulmonary vascular markings and cardiomegaly
    • Management:
      • Loop diuretics such as furosemide, digoxin, ACEIs, beta blockers and spironolactone are used.
      • Supplemental oxygen and hyperventilation should be avoided as they will cause pulmonary vascular resistance to fall which causes increased shunting.
      • Muscular VSDs often close spontaneously whereas perimembranous VSDs don’t – these are closed either surgically or via percutaneous closure by an interventional cardiologist. Surgical correction is deferred to 3-5 months which improves outcomes.
  • Atrial septal defect
    • Pathophysiology:
      • Left-to-right shunt
    • Clinical features:
      • Isolated ASDs rarely cause symptoms in infants as significant shunting doesn’t occur until right ventricular compliance is less than left ventricular compliance, causing CCF at 2-3 years old.
      • May have soft systolic murmur at upper sternal edge.
    • Diagnosis:
      • ECG: Partial RBBB, RV hypertrophy
      • CXR: Cardiomegaly, increased pulmonary vascular markings
    • Management:
      • Medical management is used to treat symptoms of CCF.
      • Surgical closure usually occurs at 3-5 years of age – 90% undergo device closure in catheter lab, 10% undergo surgical closure if defects are large.
  • Patent ductus arteriosus
    • Pathophysiology:
      • May exist in isolation or with other types of CHD.
    • Clinical features:
      • Although there is increased pulmonary flow, PDAs are usually asymptomatic in isolation. There is left-to-right shunting so that can cause CCF once the pulmonary vascular resistance falls in the first few months of life.
      • Continuous systolic murmur in the left infraclavicular area – known as a machinery murmur
    • Diagnosis:
      • ECG: Usually normal
        CXR: Increased pulmonary vascular markings if large
    • Management:
      • Two-thirds of PDAs will close with a course of indomethacin or ibuprofen as these act as prostaglandin inhibitors
      • If large enough to cause CCF → medical management is used and surgical ligation is carried out at 1-3 months
      • If there is no CCF → closure in catheter lab with a coil or device is carried out at 1 year

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