Congenital Heart Disease

• The lecture covers congenital heart diseases and their management.
• By the end of the lecture students should be able to identify the etiology and classification of congenital heart diseases as well as describe clinical presentations of ASD, VSD, Co-A, and TOF and their management.

Case Scenario

• A 25-year-old female with congenital heart disease following corrective surgery for VSD and coarctation of the aorta attends a cardiology clinic for a follow-up visit.
• The patient's vital signs are stable and she is well-nourished.
• Cardiac auscultation reveals a holosystolic murmur at the left sternal border and a continuous murmur in the left infraclavicular region.
• The patient denies chest pain, dyspnea, or palpitations.
• Her electrocardiogram shows evidence of right ventricular hypertrophy.

Introduction to Congenital Heart Disease (CHD)

• Congenital heart disease is a common congenital defect that occurs in approximately 0.6-0.8% of newborns.
• Advances in therapy have led to dramatic improvements in outcome.
• Over 85% of infants with complex CHD are expected to reach adolescence and early adulthood.
• Due to advances in pediatric cardiology and surgery, there are now more adults than children with CHD.

Etiology of Congenital Heart Disease

• Common environmental factors include maternal illness (diabetes, rubella, systemic lupus erythematosus), maternal intake of teratogenic agents (lithium, isotretinoin, antiseizure drugs), and maternal age.
• Chromosomal abnormalities that are strongly associated with congenital heart disease include: trisomy 21 (Down syndrome), trisomy 18, trisomy 13, and monosomy X (Turner syndrome).
• No identifiable genetic etiology is detected in about 72% of patients with congenital heart disease

Pathophysiology of Congenital Heart Anomalies

• Congenital heart anomalies are classified as cyanotic or acyanotic (left-to-right shunts or obstructive lesions).
• The physiologic consequences range from a heart murmur or discrepancy in pulses in asymptomatic children, to severe cyanosis, heart failure, or circulatory collapse.

Cyanotic Heart Anomalies

• Varying amounts of deoxygenated venous blood are shunted to the left heart (right-to-left shunt), which reduces systemic arterial oxygen saturation.
• The amount of deoxygenated hemoglobin that results in cyanosis is > 5 g/dL (> 50 g/L).
• The complications of persistent cyanosis include: polycythemia, clubbing, thromboembolism (including stroke), bleeding disorders, brain abscess, and hyperuricemia.
• Variable severity of cyanosis can result from reduced, normal, or increased pulmonary blood flow, which may also result in heart failure.
• Heart murmurs associated with cyanotic heart anomalies are variably audible and are not specific.

Left-to-Right Shunts

• Oxygenated blood from the left heart (left atrium or left ventricle) or the aorta shunts to the right heart (right atrium or right ventricle) or the pulmonary artery through an opening or communication.
• High-pressure shunts (ventricular or great artery level) become apparent several days to a few weeks after birth.
• Low-pressure shunts (atrial septal defects) become apparent considerably later.
• Untreated elevated pulmonary blood flow and pulmonary artery pressure may lead to pulmonary vascular disease and Eisenmenger syndrome.
• Large left-to-right shunts such as large ventricular septal defect [VSD] or patent ductus arteriosus [PDA] cause excess pulmonary blood flow and left ventricular volume overload, which leads to signs of heart failure and infant failure to thrive.
• A large left-to-right shunt can lead to lower lung compliance and higher airway resistance, which increases the likelihood of hospitalization in infants with respiratory syncytial virus or other upper or lower respiratory tract infections.

Obstructive Lesions

• Blood flow obstruction causes a pressure gradient.
• Hypertension and heart failure may result from the pressure overload proximal to the obstruction.
• A heart murmur is the most obvious manifestation, and it results from turbulent flow through the obstructed (stenotic) point.
• Examples are congenital aortic stenosis which accounts for 3 to 6% of congenital heart anomalies and congenital pulmonic stenosis which accounts for 8 to 12%.

Congenital Heart Disease in Adults

• Acyanotic lesions: atrial septal defect, ventricular septal defect, atrioventricular septal defect, pulmonary stenosis, coarctation of the aorta, patent ductus arteriosus.
• Cyanotic lesions: transposition of the great arteries, tetralogy of Fallot, congenitally corrected transposition of the great arteries.

Atrial Septal Defect (ASD)

• ASDs are common congenital heart defects in adults.
• A hole connects the atria.
• Types of ASD:
  • Ostium secundum defects (high in the septum) are most common.
  • Ostium primum defects (partial atrioventricular canal).
  • Sinus venosus defects.

ASD Symptoms

• Primum ASDs present early.
• Secundum ASDs are usually asymptomatic until adulthood since the L-R shunt depends on compliance of the right and left ventricles. Compliance decreases with age, augmenting L-R shunting, leading to dyspnoea or heart failure around age 40-60.
• Symptoms may include pulmonary hypertension, cyanosis, arrhythmia, haemoptysis, and chest pain.

ASD Signs

• Signs include AF, increased JVP, wide and fixed split S2, pulmonary ejection systolic murmur.
• Pulmonary hypertension may cause pulmonary or tricuspid regurgitation.

ASD Complications

• Reversal of left-to-right shunt, i.e., Eisenmenger’s syndrome: initial L-R shunt leads to pulmonary hypertension, shunt reversal, causing cyanosis (±heart failure & chest infections).
• Paradoxical emboli (vein-artery via ASD), is a rare occurence.

ASD Investigations

• ECG: RBBB with LAD and prolonged PR interval (primum defect) or RAD (secundum defect).
• CXR: A prominent pulmonary artery, right ventricular enlargement, and pulmonary plethora are found on chest radiographs.
• Echocardiography is diagnostic.

ASD treatment

• Before age 10, closure is suggested for children.
• Closure is indicated for adults with symptoms or for systemic blood flow ratios ≥1.5: 1.
• Transcatheter closure is more common than surgical intervention.

Ventricular Septal Defect (VSD)

• A VSD involves a hole connecting the ventricles.
• There are four main types based on the location include:
  • Membranous which is most common (80% of VSDs) in the upper section of the wall between ventricles.
  • Muscular comprises about 20% of VSDs in infants, often with multiple holes.
  • Inlet in the tricuspid valve of the right ventricle and the mitral valve of the left ventricle.
  • Subarterial- in the ventricular septum under the pulmonary valve, also called supracristal, conoseptal, or doubly committed subarterial defects.

VSD Causes

• VSDs can be congenital with a prevalence of 2:1000 births.
• VSDs can be acquired, for example post-MI.

VSD Symptoms

• Infants with moderate to large VSDs exhibit symptoms resembling heart failure, these symptoms include shortness of breath (fast breathing or difficult breathing), sweating or fatigue during feeding, failure to thrive (slow weight gain), and frequent respiratory infections,
• Older children and adults: feeling tired or out of breath easily when exercising.
• Following the development of Eisenmenger syndrome, pale skin, or a bluish tinge to skin and lips called cyanosis.

VSD Signs

• Smaller holes are haemodynamically less significant and will give louder mumurs.
• Harsh pansystolic murmur heard at the left sternal edge, systolic thrill, ± left parasternal heave.
• Larger holes are associated with signs of pulmonary hypertension.

VSD Complications

• AR
• Infundibular stenosis
• IE/SBE
• Pulmonary hypertension and Eisenmenger’s syndrome.

VSD Investigations

• ECG: normal (small VSD), LAD + LVH (moderate VSD) or LVH + RVH (large VSD).
• CXR: normal heart size ± mild pulmonary plethora (small VSD) or cardiomegaly, large pulmonary arteries and marked pulmonary plethora (large VSD).
• Echocardiogram helps identify the size of the VSD and its location.
• Computed tomography (CT) scan

VSD Treatment

• Treatment is medical at first.
• In some instance VSD close spontaneously.
• Surgical closure of is indicated with failed medical therapy, symptomatic VSD, LV volume overload, SBE/IE.
• Endovascular closure is a treatment option.

Coarctation of the Aorta

• Coarctation of the aorta is the narrowing of the descending aorta, which typically occurs just distal to the origin of the left subclavian artery.
• Coarctation of the aorta is associated with bicuspid aortic valve and Turner’s syndrome.

Coarctation of the Aorta Signs

• Radiofemoral delay (femoral pulse later than radial)
• Weak femoral pulse
• High BP
• Scapular bruit
• Systolic murmur best heard over the left scapula.

Coarctation of the Aorta Complications

• Heart failure
• Infective endocarditis.

Coarctation of the Aorta Tests

• CT or MRI-aortogram.
• CXR shows rib notching.

Coarctation of the Aorta Treatment

• Surgery, or balloon dilatation ± stenting.

Tetralogy of Fallot (TOF)

• TOF is the most common cyanotic congenital heart disorder
• The prevalence of TOF is 3-6 per 10,000.
• TOF accounts for 10% of all congenital defects.
• TOF is also the most common cyanotic heart defect that survives to adulthood.

TOF Etiology

• Believed to be caused by abnormalities in the separation of the truncus arteriosus into the aorta and pulmonary arteries that occur in early gestation.

TOF Features

• The four features include ventricular septal defect (VSD), pulmonary stenosis, right ventricular hypertrophy, and the aorta overriding the VSD.
• Some children may also have an atrial septal defect constituting a pentad of Fallot.

TOF Presentation

• Severity of illness is related to the degree of pulmonary stenosis.
• Infants may initially be acyanotic, presenting only with a murmur indicative of pulmonary stenosis.
• Gradual cyanosis develops (particularly following closure of the ductus arteriosus) due to reduced pulmonary blood flow and a right-to-left shunt across the VSD.
• The child becomes restless and agitated during a hypoxic spell- crying inconsolably.
• Toddlers may squat in order to increase peripheral vascular resistance while decreasing the amount of right to left shunting.
• Additional signs and symptoms include difficulty in feeding, failure to thrive, and clubbing.
• Adult patients are often asymptomatic.
• Cyanosis is common in unoperated adult patients, however extreme cyanosis is uncommon.
• Repaired patients symptoms tend to include: exertional dyspnoea, palpitations, RV failure, syncope, and sudden death.

TOF Investigations

• ECG shows RV hypertrophy with a right bundle-branch block.
• CXR may be normal, or show the hallmark of TOF, the classic boot-shaped heart.
• Echocardiography shows the anatomy and stenosis.
• Cardiac CT and cardiac MRI gives vital information for surgery.

TOF Management

• Give O2.
• Place the child in knee-chest position.
• Morphine can sedate the child as well as relaxing the pulmonary outflow.
• Long-term B-blockers may be needed.
• Give endocarditis prophylaxis only if recommended by a microbiologist.
• Without surgery, mortality rate is ~95% by age 20.
• Surgery is usually done before 1 year of age, with closure of the VSD and correction of the pulmonary stenosis.
• Following surgical repait 20-year survival is ~90-95%.