In a new study, researchers have shown how the chaotic electrical signals underlying irregular heart rhythms lead to the failure of standard treatments.
They modeled how electrical signals on the inside and the outside of the heart move across the muscle and showed why corrective surgery is not currently always beneficial.
The findings could improve surgery for some, by better targeting areas of the heart responsible, and could avoid unnecessary surgery for others, where intervention is unlikely to help.
The research was conducted by a team at Imperial College London.
Atrial fibrillation (AF) is the most common heart rhythm abnormality and is projected to affect about two percent of the global population by 2050.
It is the leading cause of stroke, but treatment options are limited.
The current most common treatment is surgery to burn areas of the heart from the inside thought to be responsible for the irregularity.
However, the surgery, known as catheter ablation, is only effective in about 50 percent of patients.
Clinicians in the US recently observed that AF is linked to different patterns of electrical pulses on the inside and the outside the heart, which was previously thought to be incompatible.
In the study, the team developed a model of AF that explains how these different patterns arise and what causes them. The model can further be used to explain why some patients do not benefit from AF surgery.
For example, the model predicts that the current method of burning the heart from the inside might fail if the sources underlying AF originate on the outside of the heart.
For these patients, surgery could be optimized to increase the chances of being successful and reducing symptoms.
The model also predicts that for some patients, the heart muscle is so damaged that regardless of how often the source of AF is destroyed, a new location will always emerge that disrupts the regular rhythm.
For these patients, surgery is likely to be an unnecessary risk, as well as being costly for the healthcare system. The team says new treatments should be developed for these patients.
The team’s model is currently based on theories in physics, which match well with observations of electrical pulses from earlier studies.
They are now beginning to work with real data from patients undergoing treatment to pinpoint where in the heart to target using current surgical techniques.
This could increase the success rate of current techniques and reduce the time needed for each patient to undergo surgery.
The lead author of the study is Max Falkenberg, a Ph.D. student in the Department of Physics at Imperial.
The study is published in Physical Review E.
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