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Image source: Unsplash Our hearts may change more easily than we think.

wrote an article| erqi

revisers| Clefable

In 1990, Hikaru Sato, a Japanese cardiologist, noticed a particular group of patients. All 30 patients were admitted for chest pain, shortness of breath, and on initial examination, all showed signs of heart failure.

However, when examined carefully, doctors failed to detect the typical symptoms of myocardial infarction patients (including coronary artery stenosis), and most patients did not even show any signs of heart disease.

To find out what was going on in these patients, doctors performed another test to assess the condition of their left ventricles, and the results were even more strange: the top of the left ventricle narrowed, but the bottom expanded like a balloon, shaped like the fish basket used by Japanese fishermen to catch octopus.

Because of this shape, Professor Sato named the disease Takotsubo syndrome. When looking for susceptible people and predisposing factors for this strange disease, scientists found that a large proportion of patients were women, especially postmenopausal women. Most of them experience psychological or physical stress shortly before they develop the disease, which is why it is also known as "broken heart syndrome."

Although the exact mechanism is not fully understood, the cause of this disease is clear: intense psychological and physiological stress. It is thought that during periods of intense mood swings or stress, our sympathetic nerves regulate stress hormones, triggering the fight-or-flight response. This response regulates many physiological functions, including heart rate, blood pressure, and respiratory rate.

Under normal circumstances, when the threat disappears, the reaction disappears. However, in patients with Zhang Yulou syndrome, the sympathetic connections to the brain regions that process emotions are weakened, leading to sympathetic overreaction, persistent stress hormone secretion, and ultimately left ventricular deformation.

The good news is that, for most patients, it heals within 3-6 months, and the structural and functional abnormalities of the heart can be restored.

We sometimes think that the heart, as such an important organ, should maintain a relatively stable shape after adulthood. But in fact, it's much easier to change than we think. In addition to the classic "fishbasket syndrome," many studies have found that after heart disease, the heart becomes more round-this is called cardiac sphericity and is usually measured by the ratio of the short axis to the long axis of the left ventricle. In individuals with known heart disease, increased left ventricular sphericity was also associated with poor outcomes, including ventricular arrhythmias and death.

A 2014 study also found that when astronauts spend long periods of time in weightlessness in space, their hearts become more rounded, increasing sphericity by an average of 9.4%. Fortunately, the change appears to be temporary, and shortly after returning to Earth, the astronaut's heart reverts to its normal elongated shape.

But even if we haven't experienced a heartbreak or heart attack, and haven't been to space, the shape of our hearts changes with our lifestyles. A 2019 study published in the Proceedings of the American Academy of Sciences (PNAS) found that exercise habits can change the shape of our hearts.

Exercise makes the heart grow longer? If we compare Homo sapiens to our closest relatives, chimpanzees, we can see that many of our body structures are built for endurance. Our joints absorb shock, our tendons are elastic, and even our hearts are optimized for endurance-but the degree of optimization depends on whether you exercise or are a sedentary couch potato.

Couch potato refers to someone who sits on a couch all day and watches TV (or plays with his cell phone). The term was added to the English dictionary in the 1990s In 2019, researchers at Harvard University and the University of British Colombia used ultrasound imaging to examine the heart morphology of more than 160 adult men, including long-distance runners, professional football linemen (who assist referees in making decisions at the sideline), Tarahumara (known as the "world's first running people") and sedentary adults, typical urban animals. For comparison, they also looked at the hearts of 43 adult male chimpanzees.

The Tarahumara depend on agriculture for their livelihood and, from a medical health perspective, engage in low to moderate intensity endurance exercise (EPA) throughout their lives-farming. Theoretically, they fit more closely into the "primitive" form of pre-industrial humanity. Long-term training for long-distance runners has a similar effect. Rugby linemen, on the other hand, are trained to do short, intense exercises called resistance sports (RPA), and their patterns of activity are more like chimpanzees who fight or climb every day.

The researchers found significant differences in the shape of the left ventricle between different populations and chimpanzees. Long-distance runners and Tarahumara, who engage in moderate and low intensity endurance sports, have significantly larger left ventricles, thinner walls and longer shapes-characteristics that help pump large amounts of blood over time.

In contrast, linemen have thicker ventricular walls and shorter, wider ventricles. Chimpanzees have the shortest and thickest ventricles. The researchers propose that high-intensity activity causes arterial blood pressure to spike for a short period of time, requiring such small chamber volumes, thicker walls and rounder shapes to ensure sufficient blood flow to the brain to maintain consciousness.

Left ventricular morphology in chimpanzees, sedentary people and Tarahumara, from left to right (Credit: R. E. Shave et al., Strangely, however, even without these evolutionary pressures, a sedentary, sedentary lifestyle seems to result in thicker ventricular walls and a rounder heart shape. The researchers aren't sure what causes this tendency, but at least it reminds us that maintaining moderate to low intensity exercise can make the heart "more personal."

The human heart is an extremely complex structure. Even though the relevant medicine has been developed over a long period of time, the existing diagnosis and treatment methods are still limited. At present, most of the heart examinations focus on shape and function. Studies of cardiac sphericity have focused on patients after heart attacks. A recent study published in Med speculated that the heart might begin to round before a heart attack.

The study used data from the UK Biobank. As part of the study, nearly 40,000 participants underwent magnetic resonance imaging of their hearts. Then, based on medical records, researchers counted which of them went on to develop conditions such as cardiomyopathy, atrial fibrillation or heart failure, and which did not.

The research team used deep learning techniques to automatically measure the sphericity of the heart. The results showed that people with higher cardiac sphericity were 31% more likely to develop atrial fibrillation and 24% more likely to develop cardiomyopathy in the future.

The researchers also looked at genetic factors that influence cardiac sphericity and found four genes associated with cardiomyopathy and three with a higher risk of atrial fibrillation.

Different heart shapes in healthy people (Photo source: M. Vukadinovic et al., 2023)"Changes in heart shape may be the first sign of disease," study author Christian M. Albert (Christine M. Albert said,"Understanding how the heart changes in the face of disease-and now there are more reliable and intuitive imaging to support this knowledge-is a key step in preventing such diseases."

It should be noted that this study is only speculative at present, and more and more detailed data support is needed from the real clinical application. Shaw L., a preventive cardiologist and lecturer at Stanford University School of Medicine and one of the study's corresponding authors. Shoa L. Clark Clarke also stressed: "The sphericity of the heart is not necessarily the problem itself, it may just be a sign of the problem." People with rounder hearts may have underlying cardiomyopathy or underlying molecular and cellular dysfunction of the heart muscle. We need to ask whether it is useful to include cardiac sphericity in clinical decisions. "

When you become a couch potato, your heart becomes more like a couch potato?

Source: Unsplash

Reference link:

https://www.eurekalert.org/news-releases/983948

https://www.acc.org/about-acc/press-releases/2014/03/29/09/09/may-hearts-in-space

https://www.cell.com/med/fulltext/S2666-6340(23)00069-7?_ returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2666634023000697%3Fshowall%3Dtrue#secsectitle0100

https://www.pnas.org/doi/full/10.1073/pnas.1906902116

https://www.science.org/content/article/running-or-sitting-can-change-shape-your-heart

This article comes from Weixin Official Accounts: Global Science (ID: huanqiukexue)

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