Stroke risk: Exercise can put people with narrowed arteries at risk

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A new study looks at how exercise can affect stroke risk. Drazen Zigic/Getty Images
  • New research has found that an increased heart rate can lead to a stroke in patients with highly blocked carotid arteries.
  • But for patients with no blockage or minimal blockage, exercise helped maintain healthy blood flow.
  • More 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 stricture levels, exercise recommendations include walking, yoga, and balance training to avoid falls.

While exercise is generally 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 severely blocked carotid arteries.

However, for healthy patients and those with only minimally clogged arteries, exercise has helped support healthy blood flow.

Using a computational model, the researchers simulated blood flow in the carotid arteries at the following stages of stenosis: without blockage, with 30% mild blockage, and with 50% moderate blockage. They analyzed the impact of heart rate during exercise and heart rate at rest.

For those without blockage and mild blockage, exercise was beneficial for the simulated carotid artery.

But for patients with moderate blockage, exercise has increased stress on the blocked area, which can cause the stricture to burst.

Once this blockage reaches the brain, it could eventually lead to an ischemic stroke.

Exercise is a very common practice to avoid cardiovascular disease, Somnath Roy, study author and associate professor, Department of Mechanical Engineering at Indian Institute of Technology Kharagpur, told Healthline. Existing literature has demonstrated that an exercise-induced higher heart rate improves stress levels on the artery wall and prevents the formation of a stenotic blockage. We have observed similar characteristics for healthy arteries across our numerical predictions.

However, for artery models with already progressed stenosis or narrowing, there were higher levels of oscillations in the WSS (known as the oscillatory shear rate), Roy explained.

This can increase the risk of further progression of the stricture along with very high shear stress, if levels are substantially high enough to cause rupture of the stricture plaque and formation of blood clots or emboli, which can travel to the brain and block finer vessels resulting in stroke.

The authors reported the effect of elevated heart rates on hemodynamics[how blood flows] in healthy and stenotic carotid arteries by deploying computational simulations based on physiologically relevant data. AND Not a clinical study, said Dr. Joseph C. Maroon, MD, FACS, Clinical Professor and Vice Chair, Heindl Scholar in Neuroscience, Department of Neurosurgery at the University of Pittsburgh. The observations are interesting. They’re suggesting that a lesion is 50% stenotic or greater May have an increased risk of blockage of the flow and thus lead to a stroke or heart attack.

For future studies, the research team plans to investigate the effects of high heart rate on other arterial patterns such as a coronary artery, aorta, etc., Roy explained.

In addition, they plan to examine the effect of varying blood viscosity on flow characteristics and stress levels. Blood viscosity can change due to diseases such as anemia, leukemia, sepsis, etc. They are also looking into the effects of exercise on people with heart valve replacements.

As noted in the study, vigorous exercise can have adverse effects on patients with moderate to high levels of strictures.

Although the volume of flow is not reduced until there is a 90% or greater stenosis in an artery, the suggestion is that shear and flow disturbances caused by a 50% narrowing of an artery can disrupt the flow. lining the artery (the intima) and precipitating clotting and blockage despite a normal flow, Maroon said. This is an important observation that should be further investigated and confirmed.

To better understand the relationship between exercise and stenosis, it is also important to note the potential differences between human heart rate and a computer model.

Substantial variability in human heart rate (compared to a computer model) can occur over the course of different-impact isometric workouts, sports, and exercises, said Dr. Sandra Narayanan, MD, board-certified vascular neurologist and neurointerventional surgeon at Pacific Stroke and Neurovascular Center at the Pacific Neuroscience Institute in Santa Monica, CA. Further studies are needed to understand the relationship between the duration of sustained elevated heart rate and the negative impact on cerebrovascular risk in patients with moderate-to-severe carotid artery stenosis.

Narayanan also explained that it would be useful to identify whether specific activities carry a higher risk to the lifestyle or whether the risk stems more from the tachycardia and is independent of the cause.

The study authors suggested a carefully prescribed exercise regimen for people with moderate to severe strictures or a history of stroke.

Exercise is good for healthy people to prevent arterial degeneration, Roy said. Even light exercise or a moderate increase in heart rate can be helpful for people with moderate strictures.

However, a very high heart rate can lead to fatal effects for people with severe stenosis. In the case of athletes or artists, arterial blockage often goes unnoticed and causes an elevated heart rate situation. Regular medical checkups and checking on exercise patterns will therefore be important for them, Roy added.

Low impact exercises such as walking, yoga and Tai chi are recommended.

Walk at a normal pace and gradually increase the distance, the elliptical or stationary bike at a comfortable pace but don’t run out of breath, bands for stretching and flexibility, Maroon said. Additionally, yoga, Tai Chi, and balance training can help prevent falls.

An increased heart rate can lead to a stroke in patients with highly blocked carotid arteries, according to a new study. However, for patients with no blockage or minimal blockage, exercise resulted in healthy blood flow.

To better understand the connection between exercise-induced heart rate and stenosis, more research is needed.

Experts recommend walking, yoga, and balance training for patients with moderate or higher stricture levels.

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