Congenital Heart Disease (CHD) Overview

Red Flags for Critical CHD (Emergency Department Referral)

Newborn Findings Indicative of Critical CHD: Immediate emergency response required if observed.
- Gastrointestinal Symptoms: Includes poor feeding, nausea, vomiting, diarrhea (N/V/D), failure to thrive (FTT), weight loss, dry diapers.
- Skin Signs: Observations include pallor, cyanosis, diaphoresis (sweating), and cool extremities.
- Activity Levels: Signs of lethargy, excessive sleepiness, and exercise intolerance.
- Breathing Issues: Respiratory distress and frequent upper respiratory infections (URI).
- Perfusion Indicators: Clinical signs including heart murmurs, tachycardia, decreased pulse strength, and cool extremities.
- Importance of O2 Saturation Measurement: Critical for identifying oxygen deprivation.

Critical Congenital Heart Disease (CCHD) Screening

Nature: Quick, simple, and cost-effective with low false positive rate.

Acyanotic Congenital Heart Diseases (The "Pink" Defects)

General Pathophysiology: Primarily involves left-to-right shunt. Oxygenated blood flows from the left side back to the right and into the lungs, resulting in an increased blood flow that can lead to pulmonary overcirculation and volume overload on the right heart.

1. Ventricular Septal Defect (VSD)

Description: An opening in the wall (septum) separating the left and right ventricles, most common congenital heart defect in pediatrics.
Pathophysiology: Pressure in the left ventricle exceeds that in the right, causing oxygenated blood to shunt through VSD into the right ventricle and pulmonary artery.
Presentation: Symptoms arise from pulmonary congestion: poor feeding, FTT, diaphoresis during feeds, tachypnea, increased respiratory effort, hepatomegaly.
- Characteristic Heart Sound: Loud, harsh, high-pitched systolic ejection murmur, which may intensify as flow diminishes during closure.
- Large VSDs: Can lead to a significantly unwell infant.
Types: Includes perimembranous, muscular, mid-muscular, and those adjacent to valve tissue.

2. Atrial Septal Defect (ASD)

Description: Opening in the septum between atria, described as an enlarged Patent Foramen Ovale (PFO).
Pathophysiology: Higher left atrial pressure causes oxygenated blood to shunt from left to right atrium, leading to right-sided volume overload.
Presentation: Generally benign; may close spontaneously or cause symptoms of congestive heart failure if large.
- Characteristic Heart Sound: Widely split, fixed second heart sound with systolic ejection murmur.

3. Patent Ductus Arteriosus (PDA)

General Information: Failure of the ductus arteriosus (a fetal structure connecting the aorta and pulmonary artery) to close, most commonly seen in premature infants.
Pathophysiology: The systemic pressure exceeds pulmonary arterial pressure post-birth, causing oxygenated blood to shunt through PDA into pulmonary artery, creating pulmonary overcirculation/glass discomfort.
Presentation: Symptoms include poor feeding, FTT, tachypnea, increased respiratory effort, and respiratory infections.
- Characteristic Heart Sound: Continuous machinery-like murmur.
- Other Signs: Bounding pulses and wide pulse pressure.

4. Atrioventricular Canal (AVC) / Endocardial Cushion Defect

Description: A complex defect characterized by a large hole where the atrial and ventricular septa meet.
Pathophysiology: Causes extensive mixing of oxygenated and deoxygenated blood due to a primarily left-to-right shunt.
Presentation: Varies based on shunt size and pulmonary pressures; poor feeding, FTT, tachypnea, recurrent respiratory infections, hepatomegaly.
- Characteristic Heart Sound: Loud 3-4/6 harsh holosystolic murmur.
- Associated Condition: Common in individuals with Trisomy 21 (Down Syndrome).

5. Coarctation of the Aorta (CoA)

Description: A narrowing of the aorta, usually near the ductus arteriosus; more frequent in males.
Pathophysiology: This obstructive lesion creates a pressure differential leading to high pressures before the coarctation and low pressures beyond it, potentially causing critical pressures variances and even cyanosis.
Presentation: Key signs include discrepancies between arm and leg blood pressure and perfusion.
- Classic Findings: Faint or decreased pulses in legs with normal/bounding in arms, brachial-femoral delay, and prolonged capillary refill in legs.
- Symptoms in Neonates: Tachypnea, poor feeding, pallor, and vomiting, with potential rapid progression to cardiogenic shock post-PDA closure.
- In Older Children: Often discovered incidentally due to hypertension in upper extremities.
- Associated Condition: Highly associated with Turner Syndrome.

Cyanotic Congenital Heart Diseases (The "Blue" Defects)

General Pathophysiology: Either involves a right-to-left shunt (deoxygenated blood bypassing the lungs) or inadequate pulmonary flow, leading to mixing or purely deoxygenated blood entering systemic circulation, creating a blue appearance.
Many are also ductal dependent.

1. Tetralogy of Fallot (TOF)

Description: Complex condition comprising four defects: large VSD, overriding aorta, RVOT obstruction, and RVH.
Pathophysiology: Severe RVOT obstructs blood flow to the lungs; deoxygenated blood shunts right-to-left through VSD leading to systemic circulation.
Presentation: Cyanosis can be classified (pink TOF with mild obstruction, blue TOF with significant obstruction).
- Characteristic Heart Sounds: Harsh, high-pitched systolic ejection murmur and single second heart sound (S2).
- TET Spells: Sudden acute cyanosis, often countered by a knee-to-chest posture or squatting, improving lung blood flow.
- Associated Conditions: DiGeorge Syndrome, Trisomy 21.

2. Transposition of the Great Arteries (TGA)

Description: Aorta originates from the right ventricle while the pulmonary artery arises from the left ventricle.
Pathophysiology: Creates two separate blood circulations; deoxygenated blood circulates to the body, and oxygenated blood circulates to the lungs. Reliance on PDA or ASD for mixing.
Presentation: Typically presents as blue at birth with severe cyanosis, possible respiratory distress. Classic finding includes reverse oxygen saturation differential (higher O2 saturations in lower extremities).

3. Truncus Arteriosus

Description: A single artery arises from both ventricles, overriding a VSD.
Pathophysiology: Oxygenated and deoxygenated blood mix in the truncus and VSD before being distributed, leading to systemic desaturation.
Presentation: Cyanosis at birth, poor feeding, tachypnea, poor perfusion, bounding pulses, wide pulse pressure, and failure to thrive.
- Characteristic Heart Sounds: Harsh holosystolic murmur, single S2, high-pitched diastolic murmur.
- Associated Condition: DiGeorge Syndrome.

4. Total Anomalous Pulmonary Venous Return (TAPVR)

Description: All four pulmonary veins connect poorly to the right atrium or systemic venous circulation instead of the left atrium.
Pathophysiology: Oxygenated blood returning from the lungs mixes with deoxygenated blood, requiring an ASD for any flow to reach systemic circulation.
- Types: Supracardiac, infradiaphragmatic, and intracardiac.
Presentation: Unobstructed TAPVR shows tachypnea and poor feeding.
- Obstructed TAPVR: Causes severe respiratory distress and may lead to cardiogenic shock.

5. Hypoplastic Left Heart Syndrome (HLHS)

Description: Significant underdevelopment of all left-sided heart structures, including mitral/aortic stenosis, and aortic arch hypoplasia.
Pathophysiology: Inadequate functional left ventricle; systemic blood flow relies entirely on PDA, requiring right-to-left shunting through ASD for systemic circulation.
- Ductal Dependent: Dependent on PDA survival for systemic blood flow.
Presentation: Symptoms include poor feeding, FTT, cyanosis, and tachypnea. Rapid decline to cardiogenic shock post-PDA closure.

6. Tricuspid Atresia

Description: Absence of the tricuspid valve, obstructing blood flow from the right atrium to the right ventricle.
Pathophysiology: All venous return passes through ASD to left atrium, mixes with oxygenated blood before being pumped to the body, leading to systemic desaturation.
- Ductal Dependent: Needs PDA for sufficient pulmonary blood flow.
Presentation: Presents with cyanosis at birth, poor feeding, FTT, increased respiratory effort, and tachypnea.

7. Critical Pulmonary Stenosis (PS)

Description: Severe obstruction hindering blood flow from the right ventricle into the pulmonary artery.
Pathophysiology: Prevents sufficient blood flow for lung oxygenation, leading to right-to-left shunting.
- Ductal Dependent: Needs PDA for pulmonary blood flow.
Presentation: Cyanosis, poor feeding, tachypnea, and respiratory distress. Associated with Williams or Alagille syndrome.

8. Critical Aortic Stenosis (AS)

Description: Obstruction to blood flow from the left ventricle to the aorta.
Pathophysiology: Severe obstruction leads to inadequate systemic blood flow, potentially causing cyanosis or circulatory shock.
- Ductal Dependent: Requires PDA to bypass obstruction and maintain blood flow.
Presentation: When critical, potential cyanosis, poor feeding, and other associated symptoms like those seen in Williams syndrome.

Physiological Effects of Congenital Heart Disease

Increased Preload: The right ventricle experiences volume overload from venous return.
Decreased Afterload: Blood is redirected into the pulmonary circuit, decreasing systemic resistance.
Right Ventricular Remodeling: Chronic overload can lead to ventricular dilation and hypertrophy.
Left Atrial Dilation: Increased pulmonary venous return results in enlargement of the left atrium.
Pulmonary Congestion and Edema: Excessive blood flow leads to overwhelmed pulmonary capillaries, particularly in preterm infants.
Decreased Lung Compliance: Chronic over-circulation causes stiffening of lung tissue, resulting in higher pulmonary vascular resistance.
Compromised Organ Perfusion: Risk of organ perfusion loss, which can lead to complications like necrotizing enterocolitis (NEC) and intracranial hemorrhage.

Clinical Features of Congenital Heart Disease

Tachypnea: Elevated respiratory rate.
Poor Feeding: Difficulty feeding or diaphoresis during feeding.
Hepatomegaly: A clinical sign indicative of heart failure.
Heart Murmur: Clinical sign depending on the specific defect.
Chest X-ray Findings: Signs of cardiomegaly and pulmonary congestion.
Focused History: Collect data on family history of heart problems, previous surgeries, substance use, and infant history post-birth to aid diagnostic process.
Primary Care Considerations: Recognize congenital heart disease is a lifetime issue, requiring enhanced vigilance relating to nutrition, potential arrhythmias, and comorbid conditions. Frequent doctor visits and potential hospitalizations may affect caregiver mental health.