### Date : 2024-06-25 11:22 ### Topic : Hypoplastic Left Heart Syndrome (HLHS) #medicine #cardiology #internalmedicine ---- ### Hypoplastic Left Heart Syndrome (HLHS) Overview **Hypoplastic left heart syndrome (HLHS)** is a complex and rare congenital heart defect that affects normal blood flow through the heart. In HLHS, the left side of the heart — including the left ventricle, mitral valve, aortic valve, and ascending aorta — is underdeveloped (hypoplastic). This condition prevents the heart from effectively pumping oxygen-rich blood to the body, leading to life-threatening consequences shortly after birth. ### Etiology **Congenital Defect:** - HLHS occurs during fetal development and is present at birth. - The exact cause is often unknown, but it involves genetic and environmental factors. - There may be an association with certain genetic syndromes and chromosomal abnormalities. ### Pathophysiology **Structural Abnormalities:** 1. **Underdeveloped Left Ventricle:** - The left ventricle is too small to pump blood effectively to the body. 2. **Hypoplastic Mitral and Aortic Valves:** - These valves are either too small, improperly formed, or completely closed (atretic). 3. **Small Ascending Aorta:** - The aorta, the main artery that carries blood from the heart to the body, is underdeveloped. **Circulatory Impact:** - **Compromised Systemic Blood Flow:** The underdeveloped left side of the heart cannot supply oxygen-rich blood to the systemic circulation. - **Dependency on Ductus Arteriosus:** To sustain life, blood must flow from the right side of the heart to the left side and the body through the ductus arteriosus, a vessel that normally closes shortly after birth. - **Mixing of Blood:** Oxygen-poor blood mixes with oxygen-rich blood, leading to less oxygen being delivered to the body's tissues. ### Clinical Features **Symptoms in Newborns:** - **Cyanosis:** Bluish tint to the skin, lips, and nails due to low oxygen levels. - **Difficulty Breathing:** Rapid and labored breathing. - **Poor Feeding:** Difficulty or refusal to eat, leading to poor weight gain. - **Lethargy:** Unusual sleepiness or unresponsiveness. - **Cold Extremities:** Poor perfusion leading to cold hands and feet. **Signs:** - **Heart Murmur:** An abnormal heart sound detected during auscultation. - **Weak Pulses:** Reduced pulse strength, especially in the lower extremities. - **Shock:** In severe cases, signs of shock such as low blood pressure, weak pulse, and poor perfusion. ### Diagnosis **Prenatal Diagnosis:** - **Fetal Echocardiogram:** An ultrasound of the baby's heart performed during pregnancy to detect structural abnormalities. **Postnatal Diagnosis:** - **Physical Examination:** Initial assessment based on clinical symptoms and signs. - **Echocardiography:** An ultrasound of the heart to confirm the diagnosis by visualizing the underdeveloped left heart structures and assessing blood flow. - **Chest X-ray:** May show an enlarged right heart and pulmonary congestion. - **Pulse Oximetry:** Measures oxygen levels in the blood, which are typically low in affected newborns. ### Example Case Study **Patient Profile:** - **Name:** Jee Hoon Ju - **Age:** Newborn (2 days old) - **Clinical Presentation:** Cyanosis, difficulty breathing, poor feeding, and lethargy. **Clinical Evaluation:** - **Physical Examination:** Cyanosis, weak pulses, heart murmur, and signs of poor perfusion. - **Echocardiography:** Confirms the diagnosis of hypoplastic left heart syndrome with underdeveloped left ventricle, mitral and aortic atresia, and a small ascending aorta. **Diagnosis:** Based on clinical presentation and echocardiography findings, Jee Hoon Ju is diagnosed with hypoplastic left heart syndrome. ### Management **Immediate Management:** 1. **Prostaglandin E1 Infusion:** - Administered to keep the ductus arteriosus open, ensuring blood flow from the right side of the heart to the body. 2. **Stabilization:** - Supportive care including oxygen therapy, ventilation, and fluid management to stabilize the newborn. **Surgical Interventions:** 1. **Stage 1: Norwood Procedure (First Few Days of Life):** - Reconstructs the aorta and connects it to the right ventricle, enabling the right ventricle to pump blood to the body. - A shunt is placed to provide blood flow to the lungs. 2. **Stage 2: Glenn Procedure (3-6 Months of Age):** - Connects the superior vena cava to the pulmonary artery, directing oxygen-poor blood from the upper body directly to the lungs, reducing the workload on the right ventricle. 3. **Stage 3: Fontan Procedure (2-4 Years of Age):** - Connects the inferior vena cava to the pulmonary artery, directing all oxygen-poor blood to the lungs, allowing the right ventricle to pump only oxygen-rich blood to the body. **Long-Term Management:** - **Medications:** To manage heart function and prevent complications. - **Regular Follow-Up:** Continuous monitoring by a pediatric cardiologist. - **Nutritional Support:** Ensuring adequate nutrition and growth. - **Activity Restrictions:** Tailored to the child's condition and surgical outcomes. ### Prognosis - **Survival Rates:** Improved with advances in surgical techniques and neonatal care, but long-term survival and quality of life vary. - **Complications:** Potential for arrhythmias, heart failure, thromboembolism, and developmental delays. - **Lifelong Care:** Ongoing medical care and monitoring are essential for managing complications and optimizing quality of life. ### Conclusion Hypoplastic left heart syndrome is a severe congenital heart defect requiring immediate medical intervention and multiple surgical procedures to ensure survival and improve quality of life. Early diagnosis, typically via prenatal or postnatal echocardiography, allows for timely management. While prognosis has improved with modern surgical techniques, ongoing care and monitoring are crucial for managing potential complications and supporting the child's development.