What is Keshan Disease?

Keshan disease is a kind of heart disease that was first identified in the Keshan region in northeastern China. This disease mostly appear in parts of the world where there’s not enough selenium in the soil. This is particularly common in certain remote and rural areas. It can lead to serious health problems and even death. Studies have shown a direct link between low levels of selenium in the soil and local foods and reduced selenium in the people living in those areas.

Keshan disease leads to severe damage to heart muscles, resulting in conditions like cardiogenic shock, where the heart is unable to pump enough blood to the body, and heart failure. People with Keshan disease may have symptoms including sudden heart problems, irregular heart rhythms, and heart failure.

Recent studies have also suggested that, besides lack of selenium, certain changes in genes can also cause Keshan disease. These changes in genes, known as polymorphisms and mutations, can contribute to the development of this disease. The combination of these genetic factors and low selenium levels complicates our understanding of this disease.

What Causes Keshan Disease?

Keshan disease, a heart condition, happens due to a variety of possible causes. These include a lack of selenium in the diet, genetic factors, viral or fungal infections, and malnutrition. Despite knowing these potential triggers, it’s still unclear exactly what causes Keshan disease.

Selenium is a nutrient that we acquire from different types of food like grains, meat, and fish. How much selenium is in these foods largely depends on the amount of selenium present in the soil where the plants or animal feed grow.

People tend to lack selenium in areas where the soil doesn’t have much selenium, and the local food is the main source of nutrition. This lack is noteworthy in China, where about half of the population doesn’t get enough selenium according to the standards set by the World Health Organization. The leading theory is that a lack of selenium is the main cause of Keshan disease. This idea is backed up by the fact that the number of cases dropped significantly when China introduced selenium into table salt and crops.

However, experts don’t believe that the lack of selenium is the only cause for Keshan disease. This is because not everyone deficient in selenium develops the illness. It’s believed that Keshan disease involves a mix of genetic and environmental factors, including selenium deficiency and other potential elements. Other nutritional factors that are suggested to contribute to the disease include a lack of vitamin E, protein, and certain kinds of amino acids.

Risk Factors and Frequency for Keshan Disease

Keshan disease is commonly found in specific provinces of China, as well as sporadically in countries with similar low-selenium environments. It became a significant health issue during the mid-20th century, especially between 1950 and 1970. Notable outbreaks occurred in 1959, 1964, and 1970. The disease spread throughout China, impacting over 2,900 towns in 327 counties within 15 provinces, an area where over 60 million people live.

This disease most often affects children aged 2 to 10 and women of childbearing age. Areas where Keshan disease is often seen are typically remote, rural, and economically disadvantaged. The high rates of the disease in these regions might be linked to their residents’ socioeconomic vulnerabilities.

The average yearly rate of this disease is 10 in every 100,000 people. However, some areas have much higher rates. For example, Chuxiong region in Yunnan Province saw an alarming rate of over 100 in 100,000 people, with a death rate exceeding 98%, in 1960. Though most reported cases come from China, Keshan disease has also cropped up in low-selenium areas in Russia, Korea, and Japan. Instances similar to Keshan disease were seen in Japan’s Nagano prefecture and the northern mountains of North Korea in the 1950s. This shows that the disease can occur in different countries, particularly regions with low selenium levels.

Signs and Symptoms of Keshan Disease

Keshan disease is a condition that is impacted by many factors, including where a person lives, the food they eat, their family’s medical history, and whether they have been exposed to environmental aspects seen in regions with a deficiency in selenium. There are several elements to consider when assessing Keshan disease, including a thorough check of the patient’s heart status, as the disease commonly causes heart complications, such as failing heart conditions and abnormal heart rhythms.

Keshan disease patients can be grouped into four main types according to when symptoms start, the clinical features, and how the heart is functioning. These types are:

Acute: comes on abruptly, major symptoms include severe heart issues, breathlessness, nausea, and discomfort in the chest
Subacute: sets on slower than acute, shows signs of failing heart conditions and an enlarged heart
Chronic: emerges slowly overtime, wreaks havoc on heart functionality due to a severely enlarged heart and thin heart walls
Latent: presents minor heart abnormalities initially while maintaining adequate heart function

The condition has also been linked to other concerns such as high blood pressure and selenium deficiency which has been associated with diseases like thyroiditis, Graves disease, and goiter.

Testing for Keshan Disease

Distinguishing early-stage Keshan disease from a heart condition known as idiopathic dilated cardiomyopathy can be tough for doctors. Both conditions share symptoms such as heart enlargement, reduced heart function, and irregular heartbeats. While there is no universally accepted method for diagnosing Keshan disease, an electrocardiogram (ECG) is often used as a primary non-invasive tool for detecting it.

In a long-term study involving 414 patients with early-stage Keshan disease and abnormalities in their ECG results, some patterns emerged. Nearly half of the patients showed major ECG abnormalities, like complete heart block, abnormal heart rhythm, and significant changes in the electrical activity of the heart. The other half had minor ECG irregularities, like minor changes in the electrical activity of the heart, premature beats, and variations in the rhythm of the heartbeat. Almost all patients continued to show these abnormal ECG results during the follow-up period. Patients with major ECG abnormalities were more likely to progress to chronic Keshan disease compared to those with minor ECG irregularities.

In another study comparing 71 Keshan disease patients and 290 healthy individuals, certain risk factors associated with the development of Keshan disease were identified. Roughly 30% of patients with Keshan disease had severe heart dysfunction. A significant number of patients with chronic Keshan disease also had a family history of the disease, suggesting a genetic predisposition. Most of the patients had ECG irregularities, and heart tests with the use of ultrasound (echocardiography) showed heart enlargement in all chronic cases. These findings underline the importance of family history and severe heart symptoms when assessing the risk and severity of Keshan disease.

These studies emphasize the value of using an ECG in detecting early-stage Keshan disease and predicting its progression. They also highlight the connection between a family history of Keshan disease and severe heart dysfunction. Even though there isn’t a single perfect test for diagnosing Keshan disease, a thorough evaluation including ECG, analyzing family history, heart tests with ultrasound and MRI can help rule out other heart diseases and guide diagnosis.

In measuring selenium levels, which can be related to Keshan disease, different samples like blood, urine, hair, and nails are frequently used. Among these, blood serum levels are most prone to changes, which can make them less reliable. A protein called selenoprotein P, which makes up for over 60% of selenium in the blood, is a useful indicator of selenium intake and shows fewer fluctuations.

Treatment Options for Keshan Disease

Keshan disease, which can lead to heart complications like cardiomyopathy and failure, can be managed through a combination of diuretics (medicines that help get rid of excess fluid in the body) and other recommended medical treatments. In some cases, devices may be inserted in the body to support the heart’s functioning and minimise the risk of sudden cardiac death.

A key aspect of treating Keshan disease specifically is by supplementing the patient’s diet with selenium, an essential nutrient. Sodium selenite tablets, a form of selenium, have been shown to reduce death rates in people with Keshan disease. However, it’s important to be mindful of how much selenium intake, as too much can lead to toxicity.

The US National Academy of Sciences puts the safe limit of selenium intake at 55 micrograms a day, with 400 micrograms being the maximum limit to prevent toxicity. Some studies have shown that when combined with certain heart medications like ACE inhibitors and beta-blockers, selenium supplementation can enhance survival rates in individuals with heart failure. However, an excess of selenium beyond 700 micrograms daily can cause adverse effects such as diarrhea, fatigue, hair loss, brittle hair, memory loss, and bad breath.

Another important fact to note is that a high intake of selenium can potentially increase the risk of type II diabetes. Several studies have raised this connection, although the evidence is not consistent. Concerns have been raised about elevated blood sugar levels even with a daily intake of 200 micrograms of selenium in diabetic patients for 3 months. Therefore, it’s crucial to maintain a delicate balance with selenium supplementation. The dose needs to be precise and attuned to the individual patient’s conditions to avoid any complications. It’s essential to weigh the therapeutic benefits of selenium supplementation against the risk of side effects, particularly in individuals who may be at risk of conditions like diabetes.

When trying to determine if a person has Keshan disease, doctors take into account various heart-related conditions that show similar symptoms. These conditions require careful study to avoid confusion:

Dilated cardiomyopathy: This condition also involves the widening and ineffective function of the heart. A detailed consideration of family history helps distinguish it from Keshan disease.
Ischemic heart disease: This term covers heart disorders like heart attack and chronic conditions that reduce blood flow to the heart. Like Keshan disease, it can lead to heart failure and irregular heartbeats. Doctors use heart health indicators and imaging techniques to tell them apart.
Viral myocarditis: This inflammation of the heart muscle can present symptoms similar to Keshan disease. It often demands tests for viruses, imaging, and tissue examination to diagnose accurately.
Hypertrophic cardiomyopathy: This is another condition where the heart muscle becomes abnormally thick. Examining through imaging and genetic testing helps differentiate it.
Other types of cardiomyopathy: These include medical conditions where substances like amyloid or diseases such as sarcoidosis fill the heart. Imaging and tissue biopsy assist in ruling out Keshan disease.
Nutritional cardiomyopathies: Heart diseases like wet beriberi that arise from poor nutrition present symptoms similar to Keshan disease. Dietary assessments and specific laboratory tests help in telling them apart.

By considering these conditions and conducting various tests, doctors can make an accurate diagnosis.

What to expect with Keshan Disease

The outcome of Keshan disease, a heart ailment, can greatly differ based on its stage and when treatment begins. Prompt medical care during the early and less severe phases is crucial to avoid serious complications like heart failure or a sudden drop in blood pressure due to heart dysfunction (cardiogenic shock). These complications can significantly affect the patient’s ability to recover.

People with hidden (latent) Keshan disease may show major abnormalities in their electrocardiogram (ECG), a heart test. Observations such as a completely blocked electrical pathway in the heart (complete heart block), irregular heart rhythm (atrial fibrillation), and significant alterations in the heart’s electrical activity (ST-T changes) could imply a higher risk of the disease becoming chronic.

Taking supplements of an essential nutrient called selenium is showing promising results in improving Keshan disease outcomes. One study looked into the relationship between selenium levels in the blood and the outcomes of heart failure patients in China. The results showed that particularly in patients with lower selenium levels in the blood, survival rates were noticeably affected. Patients with the lowest selenium levels had the worst outcomes and a significantly increased risk of death from any cause. This highlights the importance of selenium levels in determining a patient’s prognosis. However, the study didn’t find a clear link between selenium levels and the number of times these heart failure patients had to be readmitted to the hospital, suggesting that Keshan disease is caused by multiple factors.

Possible Complications When Diagnosed with Keshan Disease

Keshan disease can cause various complications because it affects heart function and overall health. It’s a progressive disease, meaning it gets worse over time. It causes damaging changes to the heart muscle, like multifocal necrosis (death of cells in several different areas) and fibrosis (the buildup of fibrous connective tissue), leading to serious problems.

In the acute form of Keshan disease, patients may experience cardiogenic shock, which is a serious condition that happens when the heart can’t pump enough blood to meet the body’s needs, and severe heart rhythm disorders that can threaten the life. Patients with impaired functioning of the left ventricle, a key pumping chamber of the heart, may experience sudden cardiac death due to these serious rhythm disorders.

On the other hand, chronic Keshan disease can result in heart failure, a condition where the heart cannot pump enough blood to the rest of the body. This can lead to fluid buildup in the lungs and around the body. Various heart rhythm disorders can occur, including potentially deadly ones such as complete heart block, atrial fibrillation, and ventricular rhythm disorders.

Lastly, the disease can change the structure of the heart. It can cause the heart’s chambers to become enlarged, the heart walls to weaken, and there can also be changes to the valves within the heart. These alterations raise the likelihood of congestive heart failure and associated complications.

Possible Complications:

Cardiogenic shock
Life-threatening heart rhythm disorders
Cardiac arrest
Sudden cardiac death
Heart failure
Fluid buildup in lungs and other tissues
Various heart rhythm disorders
Enlarged heart chambers
Weakened heart walls
Heart valve changes

Preventing Keshan Disease

Keshan disease often doesn’t show symptoms and can sometimes go untreated. This makes the detection and treatment of the disease a major challenge. People with this disease are at a higher risk of it becoming chronic over time, thus it’s very important to catch and treat it early. Keshan disease is mainly seen in areas where it’s historically been prevalent, which makes it a public health concern in those places.

There is a need to increase programs that boost the intake of a mineral called selenium and help patients manage the disease on their own. A key prevention strategy is using table salt mixed with selenium in the areas where the disease is most common. This strategy needs more attention and should be a priority in public health planning.

A thorough analysis by Zhou and colleagues has shown that increased intake of selenium can help prevent Keshan disease. They studied 17 different scientific studies that included nearly 2 million people and found that the people who didn’t get extra selenium had an 8 times higher risk of getting the disease than those who did. This suggests that adding selenium to the diet can help prevent the disease.

Because it was suspected that a lack of selenium could contribute to Keshan disease, measures were taken in China to increase selenium intake. This was mainly done by adding a form of selenium to table salt in regions where people generally don’t get enough of it. In one large trial that provided selenium-fortified table salt to over a million people, the incidence of Keshan disease dropped significantly, from 25.23 to 2.7 cases per 100,000 individuals. Also, the number of undetected Keshan disease cases dropped a lot more in people who got the selenium-enriched salt compared to those who didn’t. This shows that adding selenium to the diet is an effective strategy to prevent the disease.

These findings prove how critical adding selenium to the diet is in preventing Keshan disease from getting worse. The success seen in the affected regions shows the importance of continuing these selenium programs and proactive public health efforts. There should also be a focus on educating people at risk and increasing awareness to detect the disease early. This can help manage undetected cases and prevent the disease from becoming chronic.