After a common cardiac surgery, some patients experience migraines with visual auras – temporary vision disorders such as flashing lights and zigzag lines. The reason for this unusual complication was a mystery, but now research suggests that a brain clot could be the culprit.
“these [clots] Co-authors of Gregory Marcus, a cardiologist at the University of California, San Francisco, was not believed to have been thought to cause symptoms or result in obvious adverse consequences.
A new study published July 7th in the Journal Heart Rhythm proposes a new theory of why these mystical migraines become apparent.
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Any serious signs?
To treat an irregular heartbeat or an irregular heartbeat, your doctor will perform a catheter ablation. Catheter ablation involves inserting a tube into the heart, burning or injuring the heart tissue that drives irregularity. Approximately 360,000 people in the United States undergo surgery every year.
Different catheter ablation techniques can be used depending on the location of the damaged cardiac tissue. One strategy, known as “transceptal punk,” creates an opening between two heart chambers, while another strategy, known as the “reverse approach,” does not require this hole.
However, in the months following catheter ablation, 2.3% of patients with no history of migraine with visual aura reported these symptoms for the first time. The aura itself usually appears just before or after a migraine attack.
These new symptoms are because ischemic strokes that occur when blood flow to the brain are blocked are 2.6 times more likely in people under 45 who experience migraines with visual aura, and 3.7 times more likely in women of the same age who experience them. Therefore, these migraines can be a precursor to serious cardiovascular events.
Related: “This is what promotes migraine headaches”: Scientists reveal “missing links” about why some migraines occur
The Mysterious Origin of Visual Aura
Scientists have several theories as to why catheter ablation is associated with migraine. One theory assumes that holes created by diaphragmatic punctures can cause complications by rerouting blood from typical routes.
Blood usually circulates from the right side of the heart to the lungs, then to the left side of the heart and finally to the rest of the body, including the brain. However, puncture allows blood to travel directly from the left to the right heart centre, bypassing the lungs. Researchers believe that this detour can result in some type of neurotoxin (usually broken down by pulmonary enzymes) reaching the brain, causing an aura.
However, MRI scans revealed an alternative visual aura trigger: meaning brain lesions, blood clots, air bubbles or fat deposits caused by embolism, passing through the bloodstream and obstructing blood vessels in the brain.
Although migraines with visual auras also occur in people who have no history of cardiac surgery, the mechanisms behind the phenomenon are also unknown in these scenarios. Marcus said previous studies found that people experiencing these auras generally tend to also have a history of cerebral emboli.
“But it was very difficult to determine if there was a causal relationship between the two,” he said. He said that because emboli in the brain tends to be short-lived, clinicians must perform scans at about the same time as patients report their aura and find the link.
Patients undergoing catheter ablation may present opportunities to explore connections as surgery can cause more emboli. Debris from burnt heart tissue can migrate to the brain, blocking blood flow and thus starve brain tissue of oxygen and nutrients, Marcus said. Although these lesions are temporary, he and his team suspected that embolicity could be associated with the aura after cardiac surgery.
So they conducted a trial in which 63 arrhythmic patients were treated with lineage puncture and 57 were treated with a retrograde approach. The patient underwent a brain MRI scan the following day and completed a survey a month later to report a visual aura. It turns out that both surgical techniques are likely to provide a visual aura.
“Our findings here show that the presence of holes providing communication between the right and left side of the heart is not necessary at all for these visual auras to occur,” Marcus said. However, looking at MRI scans, they found that patients with postoperative cerebral embolism were 12 times more likely to develop a visual aura than patients without embolic.
Next Steps
If brain emboli is thought to not cause symptoms, it could at least partially contribute to a visual aura, Marcus added that scientists should explore whether it is also related to more serious problems like stroke.
However, new research has some weaknesses. Dr. Andrew Lee, an ophthalmologist at Houston Methodist Hospital in Texas, was not involved in the study, but said “the main limitation is self-reported migraine symptoms.” “Even validated and prospectively retrieved surveys can misclassify symptoms of certain participants,” Lee told Live Science in an email.
He also said the study did not assess whether patients have naturally occurring holes in the heart. This hole between the heart chambers forms during development and closes immediately after birth of most people, but in 25% of people it remains open. Holes are linked to migraine, visual aura, and strokes when present in adults.
The new study only investigated whether brain lesions are associated with visual aura immediately after cardiac surgery, so “future research is needed to determine whether the results of this study can generally be generalized to migraine,” Lee said.
Editor’s Note: Dr. Gregory Marcus consults and owns the shares of Incarda, a drug delivery company intended to treat cardiovascular diseases, including arrhythmias.
This article is for informational purposes only and is not intended to provide medical advice.
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