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Researchers Identify Multiple Backups to Heart’s Pacemaker
A new study sheds light on how the human sinoatrial node (SAN) efficiently maintains heart rhythm even under adverse conditions. The findings could help improve treatments for cardiac arrhythmias.
“Our most important finding was that the human SAN is hardwired with a backup system: 3 diverse regions of intranodal pacemakers acting as batteries and up to 5 conduction pathways that act as wires to connect the electric signal to the atria,” said Vadim Fedorov, PhD, senior author of the Science Translational Medicine study.1
For the research, Dr Fedorov, of The Ohio State University Wexner Medical Center, and his colleagues combined optical mapping, 3-dimensional tissue reconstruction, and molecular characterizations to create an integrated picture of the SAN in action in donated human hearts that were not viable for transplantation. The researchers placed each heart in a glass chamber and perfused the coronary arteries with an oxygenated solution that simulates blood flow, allowing the SAN to beat with the same rhythm as when it was inside the body. The chamber was then surrounded by infrared cameras, and a fluorescent dye was injected to allow the scientists to visualize spontaneous electric activity moving within the human SAN in 3 dimensions.
When the investigators disrupted SAN function with adenosine or atrial pacing, redundant intranodal pacemakers were able to compensate, ensuring a fail-safe mechanism to maintain automaticity and deliver electric impulses to the atria through sinoatrial conduction pathways.