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Single ventricle defects

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Single ventricle defects are a group of congenital heart defects where one of the heart’s ventricles (either the left or the right) is underdeveloped or non-functional. This leads to a situation where effectively only one ventricle is doing the work of pumping blood both to the lungs and to the rest of the body. These conditions are complex and often require a series of surgeries for treatment.

Types of Single Ventricle Defects

  • Hypoplastic Left Heart Syndrome (HLHS): The left side of the heart is underdeveloped.
  • Tricuspid Atresia: The tricuspid valve is not formed, leading to an underdeveloped right ventricle.
  • Double Inlet Left Ventricle (DILV): Both atria connect to the same ventricle, usually the left.
  • Pulmonary Atresia with Intact Ventricular Septum: The pulmonary valve is not formed correctly, affecting the right ventricle.


  • Cyanosis: Bluish skin, lips, and nail beds due to low oxygen levels.
  • Difficulty Breathing.
  • Poor Feeding and Growth: Especially in infants.
  • Fatigue: Older children may tire easily during physical activity.
  • Heart Murmurs.


  • Echocardiogram: Primary tool for diagnosis, providing detailed images of the heart.
  • Chest X-ray: Can show the size and shape of the heart and lungs.
  • Electrocardiogram (ECG): Measures the electrical activity of the heart.
  • Cardiac MRI or CT Scan: Offers detailed anatomical information.
  • Cardiac Catheterization: Provides detailed information about the heart’s function and structure.


Treatment involves a series of surgeries to redirect blood flow:

  • First Stage (e.g., Norwood Procedure for HLHS): Performed shortly after birth to ensure blood flow to both the lungs and the body.
  • Second Stage (e.g., Glenn Procedure): Usually performed when the child is a few months old, redirects blood from the upper body directly to the lungs.
  • Third Stage (e.g., Fontan Procedure): Conducted around 18 months to 4 years of age, directs blood from the lower body to the lungs.


  • With advances in surgical techniques, the survival rates for children with single ventricle defects have improved.
  • Long-term outcomes depend on the specific defect and the success of the surgeries.
  • Lifelong cardiac care is necessary.


  • Heart Rhythm Problems (Arrhythmias).
  • Problems with Heart Function.
  • Protein-Losing Enteropathy (especially after the Fontan procedure).
  • Blood Clots and Stroke.

Preventive Measures

  • The cause of single ventricle defects is often unknown, and there’s no specific way to prevent them.
  • Early detection through prenatal ultrasounds and genetic counseling for at-risk families can be helpful.

Children with single ventricle defects require specialized, lifelong cardiac care that often involves a multidisciplinary medical team. Advances in surgical and medical care have significantly improved the outcomes for these children, but close monitoring and management of their heart health are crucial throughout their lives.

The content is provided for informational purposes only and is not intended as medical advice or as a substitute for medical advice of a physician