- New research found an increased heart rate can lead to a stroke in patients with highly blocked carotid arteries.
- But for patients without blockage or minimal blockage, exercise helped maintain healthy blood flow.
- Further research is needed to understand the relationship between elevated heart rate and adverse impact on patients with moderate to severe carotid artery stenosis.
- For patients with moderate or higher stenosis levels, exercise recommendations include walking, yoga and balance training to avoid falls.
While exercise is typically considered good for our health, an elevated heart rate can have negative effects on people with specific health conditions.
According to a new study published in Physics of Fluids an increased heart rate can cause a stroke in patients with highly blocked carotid arteries.
However, for healthy patients and those with only minimally blocked arteries, exercise helped support healthy blood flow.
How higher heart rates can impact stroke risk
Using a computational model, researchers simulated blood flow in carotid arteries in the following stages of stenosis: without blockage, with a mild 30% blockage, and with a moderate 50% blockage. They analyzed the impact of heart rates during exercise and resting heart rates.
For those without blockage and mild blockage, exercise was beneficial for the simulated carotid.
But for moderate blockage patients, exercise increased the stress in the blocked area, which may cause the stenosis to burst.
Once this blockage reaches the brain, it could ultimately lead to an ischemic stroke.
“Exercise is very common practice to avoid cardiovascular diseases,” Somnath Roy, study author and Associate Professor, Department of Mechanical Engineering at the Indian Institute of Technology Kharagpur, told Healthline. “Existing literature showed that exercise-induced higher pulse rate improves the stress levels on the artery wall and prevents the formation of stenotic blockage. We have observed similar features for healthy arteries through our numerical predictions.”
However, for artery models with already progressed stenosis or narrowing, there were higher levels of oscillations in WSS (known as oscillatory shear index), Roy explained.
This may increase the risk of further stenosis progression along with very high shear stress, if levels are substantially high to result in the break-up of the stenotic plaque and forming blood clots or embolis, which can travel to the brain and block thinner vessels resulting in stroke.
“The authors have reported the effect of elevated heart rates on hemodynamics[how blood flows] in healthy and stenosed carotid arteries by deploying computational simulations based on physiologically relevant data. It is not a clinical study,” said Dr. Joseph C. Maroon, MD, FACS, Clinical Professor and Vice Chairman, Heindl Scholar in Neuroscience, Department of Neurosurgery at the University of Pittsburgh. “The observations are of interest. They are suggesting that a 50% or greater stenotic lesion may have increased risk of flow obstruction and thus result in a stroke or heart attack.”
For future studies, the research team plans to investigate on the effects of high heart rate at other arterial models like a coronary artery, aorta etc, Roy explained.
Additionally, they plan to look into the effect of changed blood viscosity on the flow features and stress levels. The viscosity of blood may change due to diseases like anemia, leukemia, sepsis etc. They are also looking into the effects of exercise on people with heart valve replacements.
How exercise affects stenosis
As observed in the study, intense exercise can have adverse effects on patients with moderate or higher stenosis levels.
“Although flow volume is not reduced until there is 90% or greater stenosis in an artery, the suggestion is that the shear and flow disturbances caused by a 50% narrowing of an artery can disrupt the lining of the artery (the intima) and precipitate clotting and obstruction despite a normal flow,” said Maroon. “This is an important observation that would need to be further studied and confirmed.”
In understanding more about the relationship between exercise and stenosis, it’s also important to note the potential differences between human heart rate and a computer model.
“Substantial variability in human heart rate (as compared to a computer model) can occur during the course of different-impact workouts, sports, and isometric exercises,” said Dr. Sandra Narayanan, MD, board-certified vascular neurologist and neurointerventional surgeon at Pacific Stroke & Neurovascular Center at Pacific Neuroscience Institute in Santa Monica, CA. “More study will be needed to understand the relationship between duration of sustained elevated heart rate and adverse impact on cerebrovascular risk in patients with moderate-severe carotid artery stenosis.
Narayanan also explained that it would be helpful to identify if specific activities pose more lifestyle risk, or whether risk is derived more from tachycardia and is independent of cause.
Exercise regimen for people with moderate to severe stenosis
Study authors suggested a carefully prescribed exercise regimen for people with moderate to severe stenosis or with a history of strokes.
“Exercise is good for healthy people to prevent arterial degeneration,” said Roy. “Mild exercise or moderate increase in heart rate may also be good for people with moderate stenosis.”
However, very high heart rate may lead to fatal effects for people with severe stenosis. In the case of athletes or performers, many times arterial blockage is unreported and high heart rate situation arises. Regular medical check-ups and control over exercise patterns will be thus important for them, Roy added.
Low-impact exercises such as walking, yoga and Tai chi are recommended.
“Walk at a normal pace and gradually increasing distance, the elliptical or stationary bike at a comfortable but not short of breath pace, bands for stretching and flexibility,” Maroon stated. “Also, yoga, Tai chi and balance training can help to avoid falls.”
Takeaway
According to a new study, an increased heart rate can cause a stroke in patients with highly blocked carotid arteries. However, for patients without blockage or minimal blockage, exercise resulted in healthy blood flow.
To better understand the connection between exercise-induced heart rate and stenosis, further research is required.
Experts recommend walking, yoga and balance training for patients with moderate or higher stenosis levels.
People With Blocked Arteries May Be at Higher Risk for Stroke While Exercising
Source: Pinoy Lang Sakalam
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