​Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome (HLHS) is a rare and complex congenital (present at birth) heart defect. In this disorder the left side of the heart is dangerously underdeveloped. The heart contains four chambers; two upper chambers called atria and two lower chambers called ventricles. The oxygen-poor blood enters the right side of the heart from the rest of the body, which is then pumped to the lungs to be oxygenated. The oxygen-rich blood returns to the left side of the heart and from there, pumped to the rest of the body. In a baby born with HLHS, the lower left chamber (left ventricle) is unable to pump the blood to the body as it is too small. Other parts of the heart that lay on the left side can also be underdeveloped. These include:

  • Mitral valve which controls the blood flow between the left atrium and left ventricle

  • Aortic valve which transport blood from the left ventricle into the aorta

  • Aorta, the largest artery of the blood, which supplies blood from the heart to the rest of the body

Therefore, during the first few days of life, the right side pumps the blood to the rest of the body and to the lungs. This is done through:

  • Ductus arteriosus which is a blood vessel that connects the aorta and the pulmonary artery (which carries blood from the heart to the lungs for oxygenation)

  • Foramen ovale which is a small opening between the right and left atria

Both of these connections normally close after birth. It is important to keep these connections open until the first surgical procedure. HLHS occurs during foetal development due to unknown reasons. It is more common in children who already have siblings with this disorder.

Symptoms of HLHS usually occur immediately after birth. These may include:

  • Rapid, difficult breathing

  • Pounding heart

  • Cyanosis (bluish colour of the skin, lips and nail beds)

  • Poor suckling and feeding

  • Cold hands and feet (extremities)

  • Unusual lethargy

HLHS is mostly diagnosed in babies during prenatal ultrasound. Nonetheless, you should seek immediate medical help from our doctors at the Children's Hospital Service Line at The Aga Khan University Hospital, the only internationally accredited hospital in Pakistan, if you notice the above mentioned symptoms in your child.​

HLHS can already be diagnosed in babies in the womb during a routine prenatal ultrasound. Otherwise, the doctor may suspect HLHS if your new-born has bluish tint to the skin or has trouble breathing. The doctor may also hear a heart murmur (an abnormal sound caused by turbulent flow of the blood). For confirm diagnose, your child may have to go through a series of test including:

  • Echocardiogram in which sound waves, directed at the heart from a device (transducer) placed on the chest, are used to produce images of the heart. The doctor studies the images which may reveal a smaller than normal left ventricle, aorta, and mitral and aortic valves

  • Electrocardiogram (ECG) in which the electrical activity of the heart

  • Cardiac catheterization in which a thin tube (catheter) is inserted in the arm or groin and threaded up to the inside of the heart. This is done to inject a dye in the heart to clearly visualize its structure. This procedure is performed if the non-invasive tests fail to provide adequate information​

Due to the complexity of HLHS, it is a challenging disease to care for. But our competent doctors at the Children's Hospital Services Lines at The Aga Khan University Hospital are internationally trained so they can provide exemplary medical care to your baby. Their commitment to providing quality healthcare makes them the best in the country.

HLHS is treated with step by step surgical procedures or a heart transplant. After consultation from you, your child may be admitted in the hospital. Initially, the doctor may recommend various options to stabilize their condition. These may include:

  • Medications to help dilate blood vessels and keep the ductus arteriosis open

  • Breathing assistance with a ventilator

  • Intravenous (IV) fluids

  • Feeding tube

  • Atrial septostomy in which the opening between the two atria is enlarged to promote more blood flow if the foramen ovale closes

The surgical steps include:

  • Norwood procedure which is usually performed in the first week of your baby’s life. In this procedure the doctor reconstructs the aorta and connects it to the heart’s left ventricle. A tube is inserted to make a path between the aorta and the pulmonary arteries (arteries leading to the lungs), or they place a tube to connect the right ventricle to the pulmonary arteries. At times, the doctor may perform a hybrid procedure where they implant a stent in the ductus arteriosis to keep it open, place bands around the pulmonary arteries to reduce blood flow to the lungs and create an opening between the two atria

  • Bi-directional Glenn procedure which is performed once your child is between three to six months. The doctor removes the shunt on the pulmonary artery and connects the superior vena cava (large veins that returns blood to the heart from the top half of the body) to the pulmonary artery. The blood travels from the top half of body directly to the lungs, for oxygenation, via the pulmonary artery

  • Fontan procedure which is performed once your child is between eighteen months and four years. The doctor creates a path for the oxygen-poor blood to travel from the inferior vena cava (veins that carries blood from the rest of the body) to the pulmonary artery and then to the lungs. After this procedure, the oxygen-rich and oxygen-poor blood do not mix

Heart transplant is another option, especially if the defects are very complex. Your child will be kept on medications until a donor heart becomes available.​

The Aga Khan University Hospital offers various support services to help with managing or recovering from the disease or condition. These include but are not limited to nutrition, physiotherapy, rehabilitation, specialized clinics and some patient support groups. Your doctor or nurse will advise you accordingly.

The Aga Khan University Hospital offers financial assistance to those who are in need and fulfil the eligibility criteria. For further information, you can contact the Patient Welfare Department. You can find the contact number of the Patient Welfare Department in the ‘Important Numbers’ section on the website homepage.
The financial counselling staff is available during office hours, at the main PBSD (Patient Business Services Department), to answer your financial queries on treatments’ costs and authorize admissions on partial deposit as per hospital policies allow. The financial counsellor in the emergency room is open 24/7. You can find the contact number of the Patient Business Services in the ‘Important Numbers’ section on the website homepage.​

Your doctor and or nurse will give you specific instructions about the prescribed medication. Please ensure that you take or use the prescribed medicine as advised. It can be dangerous to your health if you self-prescribe. Please inform the doctor or nurse beforehand if you have experienced any adverse reactions to any medications in the past. If you experience any symptoms of drug poisoning, overdose or severe reaction please contact the Pharmacy Service at The Aga Khan University Hospital immediately. You can find the contact number of the Pharmacy Services in the ‘Important Numbers’ section on the website homepage.

The information provided on our website is for educational purposes and not intended to be a substitute for medical advice, diagnosis or treatment. You should always seek the advice of your doctor or other healthcare professional provider.