Differences seen between the sexes in terms of stroke survival
Researchers have found that women are 39% more likely to die by one year after a first stroke, mostly due to their advanced age vs. men and having more severe strokes. Women were about seven years older compared with men in terms of first stroke. The group also found that 9.3% fewer women could walk independently on admission to the hospital, meaning they likely had experienced a more severe stroke. “Among those deceased by any cause, men had more deaths due to cancer (12% vs. women 6%) and ischemic heart disease (8% vs. women 6%) while women had more deaths attributed to stroke (50% vs. men 41%) or other cardiovascular disease (16% vs. men 13%), wrote Dominique Cadilhac, School of Clinical Sciences at Monash Health, and coauthors. The study appeared Nov. 23, 2020, in Journal of Women’s Health.
Light used to control cardiac waves
A team has used mice to study tachycardias and determined that there are intrinsic mechanisms that exist in heart tissue that they think could lead to the self-termination of rapid cardiac rhythm. "A tachycardia is a heartbeat continuously activating the heart, like a toy train endlessly going around a circular track," explained co-author Leon Glass. The group modeled tachycardias by detecting the wave in one part of the heart and stimulating another part at a fixed time later. They discovered that small changes in the delay lead to either endless circulation or self-termination of the cardiac waves. In addition, they determined that there was often an alternation of wave characteristics, such as one cycle proceeding faster and the next being slower. The researchers used optogenetics, a set of tools that allows them to stimulate and control cardiac waves with light, rather than by standard methods of electrical stimulation. Alternating dynamics, called alternans, in the heart have been associated in the past with initiation of tachycardias. With that in mind, there have been efforts to eliminate or reduce alternans. "Paradoxically, we find that alternans can also facilitate self-termination of tachycardia and might be beneficial," said co-author Gil Bub. And the group sees potential benefit in other areas, such as epilepsy, noted co-author Leonardo Sacconi. Their findings appeared Dec. 22, 2020, in Chaos.
3D-printed blood vessels ID possible link between coronavirus, stroke
A group of researchers is looking into how COVID-19 increases the risk for stroke after running fluid spiked with a COVID-19-like protein through a 3D-printed model of the arteries of a patient who had suffered a stroke. Clinicians have seen strokes in younger people who had no known risk factors before contracting COVID-19. University of California - Los Angeles researchers used a 3D-printed silicone model of blood vessels in the brain to mimic the forces generated by blood pushing through an artery that is abnormally narrowed. They showed that as those forces act on the cells lining the artery, there is an uptick in the production of angiotensin-converting enzyme 2, or ACE2, which the coronavirus uses to enter cells on the surface of blood vessels. The team fashioned the model using data from computed tomography scans of blood vessels in a human brain, lining the inner surfaces with endothelial cells. The models enabled the researchers to mimic the same forces that would act on real blood vessels during a COVID-19 infection. Another discovery offered an insight that might aid in identifying those with COVID-19 who may have a higher risk for stroke. When the researchers assessed which genes were turned on in the endothelial cells after the coronavirus spike proteins bound to them, they found that the genes that were activated were a specific set of immune-response genes that are found in brain blood vessel cells, but not in endothelial cells from other organs of the body. The paper was published in the January 2021 edition of Stroke.