While the treatment of congenital heart disease (CHD) continues to advance, children are still at risk of developing arrhythmias. An arrhythmia — an abnormal heart rhythm that can make the heart pump inefficiently — can be caused by a congenital heart condition, but it can also be the result of surgery for CHD.
The Surgical Electrophysiology Program at the Benderson Family Heart Center at Boston Children’s Hospital was created in 2020 to find new ways to treat children with CHD and arrhythmias.
Although we’ll eventually widen the scope of the program, right now we’re focused on reducing the risk of heart block during surgery for CHD. A type of arrhythmia, heart block is the partial or full blocking of electrical signals that make the heart beat and control its rate and rhythm. Heart block that occurs during surgery is usually the result of an accidental injury. Surgeons cannot see the conduction tissue that generates the electrical signals, putting it at risk of being damaged.
Innovating to reduce heart block
Our program is a collaboration of the Benderson Family Heart Center’s Department of Cardiac Surgery and the Electrophysiology Service within the Department of Cardiology. Our collective experience and appreciation for innovation is driving us to pinpoint conduction tissue during surgery so that the risk of injuring it and causing heart block in CHD patients is minimized — and someday doesn’t happen at all.
We now know it’s possible to chart the heart’s conduction system by using a catheter that’s specially outfitted for cardiac mapping. This electrophysiology (EP) tool collects electrical signals on open, beating hearts during surgical repair, letting us mark the spot of conduction tissue so we can avoid injuring it.
Our innovation has reduced heart block in many CHD surgical patients — especially those with heterotaxy who need complex biventricular repair. In that patient group, heart block has decreased from more than 14 percent to less than 3 percent when conduction mapping is used during heart surgery.
Gaining an understanding of each child’s heart
When children develop heart block they often require a pacemaker, committing them to more operations. Our ability to map the heart’s conduction system allows us to finally “see” where this tissue is located and give patients a vastly better chance of avoiding surgical complications, so they can focus on recovering from CHD treatment.
EP mapping also allows us to record the location of conduction tissue for further study. We’re finding that anatomical variables — like how a patient’s ventricles are looped, where the heart is located inside the chest, and how the atria are oriented — can influence the location of the conduction system. While some of these findings were first discovered in older anatomy studies, our rapidly growing conduction mapping experience is enabling us to better understand where the conduction system is located across all variants of complex CHD.
Our program is creating 3-D models of the heart anatomies of every CHD patient who benefits from EP mapping in surgery. Ultimately, those individual models will be available in a digital library that will let clinicians review the influences that different anatomies have on conduction, helping them take a specific approach to a surgery for a particular type of CHD.
Mapping conduction tissue is just the first of many innovations and collaborations we intend to pursue in the future, as we collectively work to better treat children with CHD and aim to reduce or eliminate altogether their risk of acquiring arrhythmia.
Electrophysiology mapping volumes
Electrophysiology (EP) mapping has become a routine part of complex congenital heart surgery at Boston Children’s. Pinpointing unseen conduction tissue has led to a significant decrease in heart block that is caused by surgical error.
Data as of September 2022