Hypoplastic Left Heart Syndrome: Causes, Symptoms, Investigations, and Treatment
A Disturbing and Disheartening condition!!
Dr. M.v. Annalarasi

Congestive Cardiac failure can occur in babies too. It is a sad truth, that a condition called the Hypoplastic Left Heart Syndrome, is one of the common causes of the failure. Hypoplastic Left Heart Syndrome is a congenital cyanotic heart defect. Congential Cyanotic heart disorders refers to a group of disease conditions that are present in babies at the time of their birth. Low levels of oxygenated blood in these heart defects causes bluish discoloration of the skin and mucous membranes. The ventricular septal defect is most commonest in this category. In this condition, the left side of the heart fails to develop fully in a fetus during pregnancy. The developmental deficit affects the normal blood flow through the heart.

To comprehend the fact of how the flow of blood is affected, let us first try to understand the normal flow. The oxygenated blood necessary for survival is pumped into the body via the left side ventricle through a major vessel called aorta. The right side of the heart pumps oxygen-poor blood from the heart to the lungs. In a fetus, there are shunts between the right and the left side of the heart. These are referred to as the ductus arteriosus and foramen ovale. These openings close after birth in normal babies. The aortic and mitral valves that control the blood flow as well the vessel (aorta) mentioned is completely narrowed, affecting the blood outflow from the left ventricle. Due to the defective left chambers, the right side of the heart works to compensate. But finally, the overload makes the right side of the heart to stop working too. As the shunts mentioned too close, the right side of the heart is not able to substitute for the left anymore as well the overwork makes the heart to fail.

Hypoplastic left heart syndrome
Hypoplastic left heart syndrome
Pic courtesy: Wikimedia Commons
Hypoplastic Left Heart Syndrome Causes

The exact cause is still a mystery. Certain studies are still trying to find if it can run in families. Some of these studies have already observed that for couples who have already had a kid with Hypoplastic Left Heart Syndrome, the chances of their next bay having the condition are more. The condition can also evolve due to severe aortic stenosis ( valve narrowing) and is also found associated with cases of Turner’s syndrome, Noonan Syndrome, Trisomy 18& 21 and Cystic Hygroma. Some other studies have also shown that taking the drug Nitrofurantoin for urinary tract infections, during early pregnancy can also lead to Hypoplastic Left Heart Syndrome


Hypoplastic Left Heart Syndrome Symptoms

Immediately after the babies are born, they might not show any signs of distress with respect to the condition as the shunts mentioned above take some time to close. The trouble begins after the closure. The neonate presents with respiratory distress, difficulty in breathing. Heavy sounds of heartbeats, heart murmurs with a weaker pulse are some of the major findings in the baby. Sometimes it might take a month while in some other cases, Congestive heart failure occurs within a week from the time of birth. Due to the circulation of deoxygenated blood( blood without oxygen), the baby turns blue- cyanotic (ash/ Bluish discoloration of the skin). From common experience, it has also been noted that just around the time when the babies are about to be discharged (approx 48 hours of age) from the hospital, a routine screening of Pulse oximetry is done. It is a test done to identify the oxygen levels in the blood, especially in babies suspected of having a critical congenital heart disease. A borderline SP02  or peripheral capillary oxygen saturation of around 88 is a warning sign for Hypoplastic Left Heart Syndrome. The baby might actually look normal and not blue, but on closer examination the skin might be a bit dusky.


Hypoplastic Left Heart Syndrome Investigations

The condition can be identified by routine screening done during 14-16 weeks of pregnancy, with the help of ultrasound. Fetal echocardiography is one of those newer emerging investigations helpful in detecting the condition. The echocardiogram can clearly depict the defective functioning of the heart in the fetus.

Hypoplastic Left Heart Syndrome Treatment

Thanks to the advancements in the field of medicine, these babies can be saved from an ill-fated journey through life, in some, if not in most cases.

One of the issues addressed by way of treatment is to ensure adequate nutrition for the babies. Special high-calorie formulas might be prescribed, for a healthy weight gain. In cases where feeding seems impossible, the babies are fed through feeding tubes.

Medical Management

The babies are treated with Prostaglandins to keep the ducts open and thus promote blood flow through the body.

Surgical Management

Most of the procedures available are more palliative in nature than being corrective. They do not cure the babies of the condition but facilitate improvement in the blood flow. The survival rate is still lower compared to most other cardiac conditions. These procedures include Norwood procedure, Bi-directional Glenn Shunt Procedure and Fontan procedure.

The development of a new staged hybrid procedure has shown some significant short and medium term favorable outcome in these babies.

Cardiac Catheterization

Cardiac catheterization is not done unless the cause of the condition is a restrictive atrial septum. In which case, atrial septectomy or balloon septostomy is performed.

Cardiac Transplant

It is one of the best options to wait for a donor heart for the baby. While the infant awaits a new organ, balloon dilation of the ductus or a ductal stent is placed to maintain an adequate ductal size.

Alarm Signal!!!

It is highly impossible for the diagnosis to be missed in the investigations done during pregnancy. But in

Hypoplastic Left Heart Syndrome
Hypoplastic Left Heart Syndrome
Pic Courtesy: Pixabay

the unlikely event that does happen, and the newborn baby develops any of the symptoms mentioned above, it is highly advisable to visit the nearest Doctor at the earliest.

Also Read

Premature Baby : causes and preventive strategies


  1. Pediatric Cardiovascular Medicine by James H. Moller, Julien I. E. Hoffman, and Julien I E Hoffman.
  2. http://www.stanfordchildrens.org/en/topic/default?id=hypoplastic-left-heart-syndrome-90-P01798
  3. Pediatric Cardiology: The Essential Pocket Guide by Walter H. Johnson, and James H. Moller.
  4. Williams Obstetrics by F. Gary Cunningham, MD, Kenneth J. Leveno, MD, Steven L. Bloom, MD, Catherine Y. Spong, MD, Jodi S. Dashe, MD, Barbara L. Hoffman, MD, Brian M. Casey, MD, Jeanne S. Sheffield, MD
  5. Moss & Adams’ Heart Disease in Infants, Children, and Adolescents by Hugh D. Allen, David J. Driscoll, Robert E. Shaddy, Timothy F. Feltes, and Allen.
  6. Hypoplastic Left Heart Syndrome Links to Chromosomes 10q and 6q and Is Genetically Related to Bicuspid Aortic Valve by Robert B. Hinton, MD, Lisa J. Martin, Ph.D., Smitha Rame-Gowda, Ph.D., Meredith E. Tabangin, MPH,‡ Linda H. Cripe, MD, and D. Woodrow Benson, MD, Ph.D.
  7. https://www.cdc.gov/ncbddd/heartdefects/index.html


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