```html

Keshan Disease – A Complete Patient‑Friendly Guide

Overview

Keshan disease (KD) is an endemic, potentially fatal form of dilated cardiomyopathy that primarily affects the heart’s ability to pump blood. First described in the 1930s in the Keshan county of southwestern Heilongjiang Province, China, the condition is closely linked to severe selenium deficiency and, in many cases, to infection with the Coxsackievirus B (CVB).

Although most cases have been reported in rural areas of China, isolated outbreaks have also been documented in parts of Russia, North Korea, and Japan where soils are selenium‑poor. The disease is most common in children and young adults (ages 5‑25) but can affect any age group, particularly those with poor nutritional status.

Prevalence reports vary, but epidemiological surveys from the 1980s–1990s estimated an average incidence of 1–2 cases per 10,000 people in high‑risk counties, with mortality rates as high as 20 % in acute forms when treatment is delayed (WHO, 1994). Nationwide selenium‑supplementation programs in China have reduced the incidence dramatically, yet sporadic cases continue to appear, especially in impoverished farming communities.

Symptoms

Symptoms of Keshan disease develop gradually in the chronic form or abruptly in the acute (fulminant) form. Below is a comprehensive list with brief explanations.

Cardiac‑related symptoms

• Dyspnea (shortness of breath) – initially on exertion, later at rest.
• Fatigue and weakness – due to reduced cardiac output.
• Palpitations – irregular or rapid heartbeats.
• Chest discomfort – often described as pressure rather than sharp pain.
• Peripheral edema – swelling of the ankles, feet, or abdomen.
• Orthopnea – difficulty breathing when lying flat.

Systemic symptoms

• Loss of appetite & weight loss – common in chronic malnutrition.
• Fever & malaise – may accompany viral infection.
• Exercise intolerance – early tiring during routine activities.
• Chest tightness after meals – a sign of post‑prandial heart failure.

Acute (fulminant) presentation

• Sudden onset of severe dyspnea.
• Rapid heart rate (>120 bpm) or profound bradycardia.
• Hypotension (blood pressure <90/60 mmHg).
• Altered mental status (confusion, fainting).
• Cold, clammy skin.

Causes and Risk Factors

Keshan disease is multifactorial. The two primary contributors are:

1. Selenium deficiency

• Selenium is an essential trace element needed for the enzymes glutathione peroxidase and thioredoxin reductase, which protect heart muscle cells from oxidative damage.
• Soils in parts of northeastern China contain < 0.05 µg Se/g, far below the 0.5–1.0 µg Se/g required for adequate dietary intake.
• People who rely on locally grown rice, wheat, and corn—crops that absorb little selenium—are at highest risk.

2. Coxsackievirus B (CVB) infection

• CVB is an enterovirus that can cause myocarditis. In a selenium‑deficient host, the virus replicates more aggressively, leading to severe myocardial injury.
• Outbreaks of KD often follow seasonal peaks of CVB infection (spring–early summer).

Additional risk factors

• Geographic location – living in selenium‑deficient regions.
• Poor nutrition – diets lacking animal protein, seafood, or fortified grains.
• Low socioeconomic status – limited access to diverse foods or supplements.
• Age – children and adolescents with rapid growth demands.
• Genetic susceptibility – polymorphisms in selenoprotein genes may increase vulnerability (J. Nutr., 2021).

Diagnosis

Diagnosing Keshan disease requires a combination of clinical suspicion, laboratory testing, imaging, and sometimes tissue analysis.

1. Clinical evaluation

• Detailed history focusing on residence, diet, recent viral illness, and family history of cardiomyopathy.
• Physical exam looking for signs of heart failure (elevated JVP, murmur, edema).

2. Laboratory tests

• Serum selenium level – < 70 µg/L suggests deficiency (WHO reference).
• Cardiac biomarkers – elevated troponin I/T or CK‑MB indicate myocardial injury.
• Complete blood count & inflammatory markers – may reveal viral infection (elevated CRP, ESR).
• Viral serology / PCR – detection of CVB RNA in blood or throat swabs.

3. Imaging studies

• Echocardiography – hallmark finding: dilated left ventricle with reduced ejection fraction (often <40 %).
• Chest X‑ray – cardiomegaly and pulmonary congestion.
• Cardiac MRI – identifies myocardial edema and fibrosis; helpful when echo is equivocal.

4. Endomyocardial biopsy (rare)

Reserved for atypical cases; may show non‑specific inflammatory infiltrates and viral particles.

5. Diagnostic criteria (simplified)

1. Residence in a known endemic area or documented selenium deficiency.
2. Clinical signs of dilated cardiomyopathy.
3. Exclusion of other causes (ischemic heart disease, hypertension, alcoholic cardiomyopathy, etc.).
4. Supporting evidence: low serum selenium and/or positive CVB test.

Treatment Options

Management of Keshan disease is three‑pronged: re‑plenish selenium, treat the heart failure, and address the underlying viral infection.

1. Selenium supplementation

• Oral sodium selenite – 200 µg daily for 3 months, then 100 µg maintenance (adjusted by serum levels).
• Intravenous selenium may be used in critically ill patients (e.g., 500 µg bolus then 100 µg/day).
• Monitoring: repeat serum selenium at 4‑week intervals.

2. Heart‑failure therapy (guideline‑based)

• ACE inhibitors or ARBs – reduce afterload and remodeling.
• Beta‑blockers (e.g., carvedilol, metoprolol succinate) – improve survival.
• Mineralocorticoid receptor antagonists – spironolactone or eplerenone for symptomatic patients.
• Loop diuretics – relieve congestion (furosemide, torsemide).
• Digoxin – may be added for atrial fibrillation or refractory symptoms.

3. Antiviral / immunomodulatory treatment

• There is no specific antiviral approved for CVB; however, early use of **intravenous immunoglobulin (IVIG)** (2 g/kg over 2‑5 days) has shown benefit in severe viral myocarditis (JACC, 2020).
• Corticosteroids are controversial; they may be considered in life‑threatening inflammation after weighing infection risk.

4. Advanced interventions

• Mechanical circulatory support – intra‑aortic balloon pump (IABP) or extracorporeal membrane oxygenation (ECMO) for fulminant KD.
• Implantable cardioverter‑defibrillator (ICD) – for patients with LVEF < 35 % and documented ventricular arrhythmias.
• Heart transplantation – rare, reserved for end‑stage disease unresponsive to medical therapy.

5. Lifestyle & supportive care

• Low‑sodium diet (<2 g/day) to reduce volume overload.
• Regular, moderate aerobic exercise as tolerated (under cardiology supervision).
• Vaccination against influenza and COVID‑19 to lower risk of viral triggers.

Living with Keshan Disease

Even after acute stabilization, lifelong management is essential.

Medication adherence

• Use a pill organizer and set daily alarms.
• Never stop ACE inhibitors, beta‑blockers, or selenium without consulting your doctor.

Monitoring

• Check weight every morning; a gain of >2 kg in 3 days may signal fluid retention.
• Blood pressure and heart rate should be recorded at least twice weekly.
• Annual echocardiograms to track ventricular size and function.

Nutrition

• Incorporate selenium‑rich foods: Brazil nuts (≈68 µg/se‑nut), seafood (especially tuna, sardines), eggs, and legumes.
• Maintain a balanced diet with adequate protein to support myocardial repair.
• Work with a dietitian familiar with trace‑element deficiencies.

Psychosocial support

• Join patient support groups (e.g., Chinese Cardiomyopathy Association) for shared experiences.
• Address anxiety or depression through counseling; chronic heart disease can affect mental health.

Regular follow‑up

Schedule cardiology visits every 3–6 months, or sooner if symptoms change. Keep a log of any new chest pain, palpitations, or swelling.

Prevention

Because the disease is largely environmental, public‑health measures are the cornerstone of prevention.

• Soil and crop fortification – Selenium fertilization of wheat, rice, and corn has reduced regional incidence by >80 % (Chinese CDC, 2012).
• Dietary supplementation – Community distribution of selenium tablets (100 µg) to at‑risk populations.
• Improved nutrition education – Encouraging consumption of animal proteins and nuts.
• Viral infection control – Hand hygiene, safe water, and prompt treatment of febrile illnesses.
• Screening programs – Annual serum selenium checks for children in endemic villages.

Complications

If Keshan disease is not promptly treated, the following complications may arise:

• Progressive heart failure – leading to refractory pulmonary edema and renal dysfunction.
• Life‑threatening arrhythmias – ventricular tachycardia or fibrillation.
• Thromboembolic events – atrial fibrillation can precipitate stroke.
• Cachexia – severe weight loss and muscle wasting.
• Multi‑organ failure – especially in fulminant cases requiring ECMO.
• Psychological impact – depression, reduced quality of life, and social isolation.

When to Seek Emergency Care

---

References (selected):

• World Health Organization. Keshan disease – review of epidemiology and control. WHO Technical Report Series, 1994.
• Mayo Clinic. Dilated cardiomyopathy. Updated 2023.
• Chinese Center for Disease Control and Prevention. National selenium supplementation program outcomes. 2012.
• J. Nutr. “Genetic polymorphisms of selenoprotein genes and susceptibility to Keshan disease.” 2021.
• JACC. “Intravenous immunoglobulin in viral myocarditis: a randomized trial.” 2020.
• Cleveland Clinic. Heart failure medication guide. Accessed 2024.

```