Protecting Children's Brains during Heart Surgery

Children with heart defects often face threats to their brain's health and development. The time during and shortly after a surgery is especially risky for the brain. During a procedure, the brain can be at risk because of: 

• Medications 

• Low oxygen  

• Unusual blood flow 

The brains of babies and very young children are especially vulnerable to injury during or shortly after a medical procedure.  When patients experience a brain injury before, during, or after surgery, they may have new problems with thinking, learning, and moving their bodies.  

Neuroprotective strategies can lessen the likelihood that the brain will be injured during a medical procedure. 

When a person’s body is very cold, they require much less oxygen than when their body is a normal temperature.  This means that cooling the body prior to surgery can make it less likely that a person will experience an injury from low oxygen.  When using hypothermia, the surgical team will: 

• Cool the body slowly using a heart-lung machine 

• Shut off the heart-lung machine during the surgery so blood flow stops 

• Turn the machine back on, and slowly warm the body back up after the surgery 

Antegrade cerebral perfusion is a method of supplying some blood flow to the brain, even when blood flow is stopped in the rest of the body during a surgery.  It can allow patients to remain warmer during surgeries, and may reduce injuries and complications.   

Before and during an operation, doctors manage the amount of oxygen and carbon dioxide gas in the blood using the heart-lung machine.  By managing the blood gas levels, doctors can help make sure that enough oxygen is delivered to the brain. 

The “hematocrit” is the amount of red blood cells in the blood.  When a patient is on the heart-lung machine, doctors manage the hematocrit to make sure that the blood is neither too thick nor too thin.  When the hematocrit is optimized, blood can most effectively bring oxygen to the brain.  

During a heart surgery, doctors make sure to keep a patient’s blood sugar and blood pressure at just the right level. Blood pressure that is either too low or too high can be dangerous for a patient. Low blood sugar can lead to brain injuries.  Doctors monitor these levels through the heart-lung machine. 

During surgeries, doctors closely monitor patients’ brain activity so that they can notice any sign of possible problems.  If they can detect signs of problems early, then they can intervene to either prevent or reduce brain injury.  This process is called “Neuromonitoring.”   

Surgical teams select tools to monitor a patient’s brain during an operation.  If they detect a change, they intervene quickly to try to protect the brain.  Monitoring tools include: 

“Near Infrared Spectoscopy” or “NIRS” is a tool that can measure oxygen levels in the brain. A doctor puts sensors on the patient’s scalp.  Doctors can use the sensors to monitor for any large drops in oxygen in the brain. 

“Transcranial Doppler” (TCD) is a type of ultrasound that creates images of the blood vessels in the brain.  TCD can detect changes or blockages in blood flow, which might be dangerous to a patient.  

Patients and their families have a right to know what to expect before, during, and after any procedure. Families should feel comfortable asking the medical team to discuss neuroprotection. When everyone understands the plan and works together, they have a better chance of providing the best possible outcome to the patient.

This content was reviewed by a pediatric cardiac surgeon at Boston Children's Hospital.

Developmental care is best when it is local. Families local to Boston can receive care from the Cardiac Neurodevelopmental Program (CNP). Families from other regions can use the link below to find their local care team.