Overview of Congenital Heart Disease
This article provides a brief overview of congenital heart disease, including its subtypes, clinical signs, investigations, and management.
- Clinical signs
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Acyanotic cardiac lesions include:
- Ventricular septal defects (VSD)
- Atrial septal defects (ASD)
- Patent ductus arteriosis (PDA)
Acyanotic cardiac lesions have the following features:
- Left to right shunting, mixing of oxygenated blood with deoxygenated blood
- Increased pulmonary blood flow, resulting in a risk of pulmonary hypertension and untreated acyanotic heart disease leading to Eisenmenger syndrome
- Lesions above the level of the nipple typically give rise to ejection systolic murmurs, while lesions below the level of the nipple typically cause pan systolic murmurs
Ventricular Septal Defect (VSD)
Symptoms vary depending on the size of the defect:
- Small -may be asymptomatic, normal growth
- Moderate -poor feeding, failure to thrive (FTT), shortness of breath (SOB)
- Large -poor feeding, FTT (falls below centiles), SOB, sweaty and pale with feeds
- Most common congenital heart lesion (15-20%)
- Associated with Down's syndrome (AVSD)
Time of Presentation
- Antenatal diagnosis at 16-18 weeks
- Presentation at 6-8 weeks
- Congestive heart failure typically presents after 4-6 weeks
- Persistent pulmonary hypertension of the newborn (PPHN) may become established by 6-12 months
- Check for the presence of a thrill
- It may be useful to palpate the liver (can be enlarged in heart failure)
- Pan-systolic murmur heard loudest at the lower left sternal border (LLSB)
- Typically grade 3-4
- Loud P2 suggests the presence of pulmonary hypertension
- Pulse oximetry -to determine oxygen saturation level
- Echocardiography -to visualize defect directly
- CXR -cardiomegaly and pulmonary edema (increased pulmonary vascular markings) if severe VSD (heart failure present), enlarged pulmonary artery
- In patients with moderate or large VSD, the ECG may demonstrate LV hypertrophy (LVH) causing increased voltage in V5 and V6 or leads II, III, and aVF
- In patients with elevated RV pressure, the ECG demonstrates RV hypertrophy (RVH) typically manifesting as tall R waves in leads V4R and V1, or upright T waves in these leads past the first 24 hours of life, in addition to LVH
- Small lesion: less than 5mm usually close spontaneously, no repair required (30-40%)
- Moderate lesion:
- Diuretic therapy (furosemide and spironolactone)
- Feeding with high calorie feeds (Infantrini)
- Large lesion:
- Manage as per moderate lesion
- Optimize weight gain for surgery
- Schedule for surgery before 12 months to prevent persistent pulmonary hypertension of the newborn (PPHN)
Atrial Septal Defect
- Typically asymptomatic
- Some children may experience recurrent chest infections
- Second most common acyanotic heart lesion (5-10%)
Time of Presentation
- Mean age for diagnosis is 4.
Patent Ductus Arteriosus
Patent ductus arteriosus (PDA) is one of the most common congenital heart defects and affects 5-10% of all individuals. It is especially common in preterm infants.
Time of presentation
Symptoms of PDA usually present 3-5 days after birth when the duct begins to close, though may remain asymptomatic for the first 5 years.
- Palpate: Might be useful to palpate the liver (enlarged in heart failure), bounding pulses and wide pulse pressure.
- Auscultate: Continuous machinery murmur typically heard at the upper-left sternal border (best heard below the clavicle), check for the presence of a thrill at the upper-left sternal border.
The best diagnosis is confirmed through 2D echocardiography and Doppler. CXR and ECG are less useful in diagnosing PDA.
- If preterm, it has a good probability of spontaneous closure. If term, it is less likely to close spontaneously.
- Medical -indomethacin/ibuprofen (not effective in term infants).
- Surgical -catheter closure or PDA ligation (left lateral thoracotomy incision) when weight is at least 5kg.
Outflow Tract Obstruction: Coarctation of the Aorta
- A left ventricle outflow tract obstruction raises the left ventricular afterload, causing left ventricular hypertrophy.
- Neonates with severe aortic coarctation may experience heart failure.
- Approximately 5% of congenital heart defects.
- Frequently seen in girls with Turner's Syndrome (5-15% probability).
Time of Presentation
- Symptoms may present 3-5 days after birth when the ductus begins to close due to a PDA and foramen ovale which allow blood to bypass the outflow obstruction.
- Systolic blood pressure will be high when measured with a BP cuff.
- A lack of femoral pulses (perform a 4-limb BP measurement).
- Cold extremities (especially feet).
- Hepatomegaly may occur with severe coarctation resulting in heart failure.
- Listen for a murmur heard at the back between the scapulae.
- A 2D echocardiogram and Doppler can give a direct visualisation of the defect.
- CXR and ECG have limited diagnostic utility.
- Continuous intravenous infusion of prostaglandin E1 keeps the ductus arteriosus open.
- Dopamine or Dobutamine can be used to improve contractility in those with heart failure.
- Supportive care can address metabolic acidosis, hypoglycemia, respiratory failure, and anaemia, which may be contributing factors or consequences of heart failure.
- Balloon angioplasty.
- Resection with end-to-end angioplasty.
- A bypass graft.
- A subclavian flap.
Cyanotic Lesions (6 Ts)
Cyanotic lesions occur from the mixing of deoxygenated and oxygenated blood (right to left shunt). The differential diagnoses of cyanotic lesions using the 6 Ts are: Tetralogy of Fallot, Transposition of Great Arteries, Truncus Arteriosus, Total Anomalous Pulmonary Venous Connection, Tricuspid Valve Abnormalities, and any number of other causes (i.e. hypoplastic left heart, double outlet right ventricle, and pulmonary atresia.
Tetralogy of Fallot
Tetralogy of Fallot comprises of four abnormalities: a Ventricular Septal Defect, Overriding Aorta, Pulmonary Stenosis, and Right Ventricular Hypertrophy.
- Poor feeding.
- Sweating during feeds.
- 7-10% of congenital heart disease.
Time of Presentation
- During the neonatal period when the Patent Ductus Arteriosus begins to close (day 3-5).
- Cyanotic “tet” spells arise from increased RV to LV shunting due to pulmonary stenosis causing RV outflow tract obstruction.
- An ejection systolic murmur may be present due to RVOTO caused by pulmonary stenosis. It is crescendo-decrescendo in quality, heard loudest at the upper-left sternal angle with posterior radiation.
Investigations and Management of Ventricular Septal Defect (VSD) and Transposition of the Great Arteries (TGA)
- 2D echocardiogram and Doppler -to assess location and number of VSDs and severity of RVOTO
- ECG -shows right atrial enlargement and right ventricular hypertrophy (right axis deviation, prominent R waves anteriorly and S waves posteriorly)
- CXR -classic “boot-shaped heart”, with a right aortic arch seen in 25% of patients
- Cardiac catheterisation can help further delineate cardiac lesion, particularly helpful for assessing levels of right ventricular outflow obstruction
Neonates with severe cyanosis: prostaglandin infusion to maintain patency of ductus and pulmonary flow until the time of surgical repair
- Tet spells:
- Knee to chest position to increase systemic vascular resistance and promote blood flow into the pulmonary circulation
- Heart failure: digoxin and loop diuretic (furosemide)
- Prophylaxis for endocarditis: antibiotics
Surgical repair -Blalock-Taussig shunt
Transposition of the Great Arteries
The aorta arises from the RV and pulmonary artery from the LV, resulting in deoxygenated blood from the RV being circulated around the body
- Poor feeding, sweating during feeds
- TGA accounts for about 3% of all congenital heart disease, and 20% of all cyanotic heart disease
- Without treatment, 90% will die within the first year of life
Time of presentation
- During neonatal period when the patent ductus arteriosus begins to close (day 3-5)
- Fetal ultrasound
- CXR -classic “egg on a string” appearance
- ECG and cardiac catheterisation is typically not used in the diagnosis of TGA
- Balloon atrial septostomy to increase mixing of the two circulatory systems
- Arterial switch procedure
- Still's murmur
- Venous hum
- Turbulent flow in the pulmonary artery bifurcation
25% of full-term neonates have a murmur
Features of an innocent murmur (10 ‘S’)
10 ‘S’ of innocent murmur:
- S1 and S2 normal
- Special test (X-ray and ECG) normal
- Standing/sitting vary with position
- Sternal depression
A soft vibratory murmur heard over the lower-left sternal border most frequently in childhood when there is normal blood flow and no cardiac lesion.
Continuous murmur heard loudest over the clavicles due to venous return from the head and neck, and this varies with position.
Turbulent flow in pulmonary artery bifurcation
A soft ejection systolic murmur caused by turbulent flow in the pulmonary artery (PA) bifurcation as the PA bifurcation and branches are small.