In a new study, researchers discovered a backup natural pacemaker, which is able to generate a pulse and control the heart rate.
The finding has important implications on the work of cardiologists and heart surgeons.
The research was conducted by a team at the University of Manchester and elsewhere.
In the study, the team found that a ‘subsidiary atrial pacemaker’ (SAP) takes over from the nearby sinoatrial, or SA Node, the primary way the heart generates electrical signals that make it beat, when it fails.
The SA node in human, goat and other mammalian species is a group of cells located in the wall of the right atrium of the heart which have the ability to spontaneously produce the electrical impulses to make our hearts beat.
The team are confident the discoveries are highly relevant to the human heart, as the organ in goats has similar anatomy and physiology, producing a similar heart rate.
When the SA node doesn’t work as it should, the heart rate can slow down causing breathlessness and blackouts.
However, when the malfunctioning SA node is removed by cardiologists in a procedure known as ablation, the new structure discovered by the team carrying out the research in goats took over as the dominant pacemaker, which also drives the electrical activity of the heart.
And even though electrocardiograms (ECGs) – which provide an electrical map of the heart—have slightly different shapes for each natural pacemaker, the heart still functioned normally when using the SAP.
The study also explains why ablation of the SA node—sometimes performed by cardiologists to treat a fast heartbeat called inappropriate sinus tachycardia—is often unsuccessful.
The research shows that the SA node is difficult to completely destroy using ablation and even if a few cells of the SA node are left, they find, it will continue to function as the heart’s pacemaker.
The team says the heart is a complex organ that contains many different types of specialist cells serving distinct functions.
These include the cells in the heart’s own ‘pacemaker,” which generates the electrical signal triggering each heartbeat.
The findings will inform future work to better understand and treat human diseases associated with abnormal pacemaker activity.
One author of the study is Dr. Halina Dobrzynski.
The study is published in Frontiers in Physiology.
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