Tetralogy of Fallot and Heart Defects

• Tetralogy of Fallot, Tricuspid Atresia and Eisenmenger Syndrome are heart defects characterized by decreased pulmonary blood flow.

Tetralogy of Fallot

• Tetralogy of Fallot (TOF) is a congenital heart defect with four anatomical abnormalities.
• These include: Ventricular Septal Defect (VSD), Overriding Aorta, Pulmonary Stenosis, and Right Ventricular Hypertrophy.
• The severity of pulmonary stenosis varies among individuals with TOF and largely determines the symptoms and prognosis.
• Right Ventricular Hypertrophy is a secondary effect, resulting from the increased workload on the right ventricle due to the pulmonary stenosis.
• A Ventricular Septal Defect (VSD) is an opening between the right and left ventricles, allowing blood to flow between them.
• In TOF, the aorta is positioned over both ventricles (overriding), allowing blood from both ventricles to enter the systemic circulation.
• Pulmonary stenosis is a narrowing of the pulmonary valve and outflow tract, obstructing blood flow to the lungs.
• Clinical manifestations of TOF include cyanosis, dyspnea, fatigue, and delayed growth.
• Older children with uncorrected TOF may develop clubbing of the fingers and toes.
• Hypercyanotic spells, also known as "tet spells," can occur, characterized by a sudden increase in cyanosis, often triggered by crying or feeding.
• Diagnosis involves echocardiography, electrocardiogram (ECG), and chest X-ray to visualize the heart's structure and function.
• Treatment usually requires surgical repair.
• Complete repair involves closing the VSD and relieving the pulmonary stenosis.
• Some infants may need a temporary shunt to improve pulmonary blood flow before complete repair.
• Postoperative, patients require regular cardiology follow-up to monitor for potential complications like arrhythmias or pulmonary valve regurgitation.

Tricuspid Atresia

• Tricuspid Atresia is a congenital heart defect characterized by the absence of the tricuspid valve, which normally allows blood to flow from the right atrium to the right ventricle.
• It results in hypoplasia of the right ventricle, as well as interatrial communication through a patent foramen ovale or an atrial septal defect (ASD).
• Blood flows from the right atrium to the left atrium through an ASD, mixing with oxygenated blood.
• A ventricular septal defect (VSD) is usually present, allowing some blood to flow from the left ventricle to the pulmonary artery, mitigating complete lack of pulmonary flow.
• Clinical manifestations are typically evident in newborns and include cyanosis, difficulty breathing, and fatigue.
• Long-term cyanosis can lead to clubbing of the fingers and toes.
• Diagnosis involves echocardiography, ECG, and cardiac catheterization to assess the heart's anatomy and pressures.
• Initial management includes prostaglandin E1 (PGE1) infusion to maintain patency of the ductus arteriosus, ensuring pulmonary blood flow.
• Surgical interventions are multistaged.
• The first stage often includes a Blalock-Taussig shunt to increase pulmonary blood flow.
• A Glenn shunt (bidirectional cavopulmonary anastomosis) may be performed, connecting the superior vena cava to the pulmonary artery.
• The Fontan procedure connects the inferior vena cava to the pulmonary artery, directing systemic venous return to the lungs without a pumping ventricle.
• Post-Fontan, patients require long-term monitoring.
• Complications include arrhythmias, protein-losing enteropathy, and liver dysfunction.

Eisenmenger Syndrome

• Eisenmenger Syndrome is a condition that develops from long-standing, uncorrected congenital heart defects with left-to-right shunting.
• Over time, increased pulmonary blood flow leads to pulmonary hypertension and vascular remodeling.
• The pulmonary hypertension eventually causes the shunt to reverse, becoming a right-to-left shunt.
• Common underlying defects include VSD, ASD, and patent ductus arteriosus (PDA).
• In the early stages (left-to-right shunt), oxygenated blood from the left side of the heart recirculates to the lungs, increasing pulmonary blood flow.
• Prolonged increase in pulmonary blood flow causes vasoconstriction and structural remodeling of the pulmonary vasculature.
• Pulmonary hypertension increases right ventricular pressure, eventually exceeding left ventricular pressure and reversing the shunt.
• Once the shunt reverses, deoxygenated blood enters the systemic circulation, causing cyanosis.
• Clinical manifestations include cyanosis, dyspnea, fatigue, chest pain, and syncope.
• Additional signs may include clubbing of the fingers and toes, edema, and heart failure symptoms.
• Diagnosis involves echocardiography, cardiac catheterization, pulmonary function tests, and blood tests.
• Echocardiography assesses the heart structure and estimates pulmonary artery pressure.
• Cardiac catheterization directly measures pulmonary artery pressures and assesses the degree of shunt reversal.
• Pulmonary function tests evaluate lung function and rule out other causes of dyspnea.
• Management focuses on supportive care and symptom management.
• Medications include pulmonary vasodilators to reduce pulmonary artery pressure, such as endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and prostanoids.
• Oxygen therapy can help alleviate hypoxemia and reduce pulmonary vasoconstriction.
• Phlebotomy may be necessary to reduce blood viscosity in patients with significant polycythemia.
• Advanced therapies include lung or heart-lung transplantation in severe cases.
• Patients with Eisenmenger Syndrome require lifelong monitoring and specialized care, avoiding strenuous activity, dehydration, and situations that exacerbate hypoxemia.