Cardiac Beriberi

Cardiac beriberi is the cardiovascular manifestation of thiamine (vitamin B1) deficiency. It causes high output heart failure with peripheral vasodilatation (wet beriberi), and in its fulminant form (Shoshin beriberi) cardiogenic shock with severe lactic acidosis. It is fully reversible if treated early.

It is seen in chronic alcohol use disorder, populations with polished rice or otherwise monotonous diets, food insecurity, bariatric surgery, persistent vomiting and hyperemesis, malabsorption, prolonged parenteral nutrition without vitamins, refeeding, dialysis, HIV and prolonged high dose loop diuretic use.

Thiamine stores last only 2 to 3 weeks, so deficiency develops quickly with poor intake. Dry beriberi (neuropathy) and Wernicke-Korsakoff syndrome can coexist.

Pathophysiology.

Thiamine pyrophosphate is the cofactor for pyruvate dehydrogenase, alpha ketoglutarate dehydrogenase and transketolase. Deficiency blocks aerobic metabolism, causing lactate accumulation, energy failure and metabolic acidosis.

Lactate and other metabolites cause marked peripheral vasodilatation and arteriovenous shunting, lowering systemic vascular resistance and raising cardiac output. Fluid retention follows renal hypoperfusion and neurohormonal activation, producing congestion despite a high output state.

In Shoshin beriberi, cardiac output may not be raised, and shock is driven by acidosis and myocardial energy failure.

Dyspnoea, orthopnoea, oedema, palpitations, wide pulse pressure, warm peripheries, bounding pulses, tachycardia, raised jugular venous pressure, a third heart sound, and cardiomegaly. Peripheral sensorimotor neuropathy, calf tenderness, anorexia and weight loss are often present. Neurological features (ophthalmoplegia, nystagmus, ataxia, confusion) indicate Wernicke encephalopathy.

Diagnosis is clinical, and treatment must not wait for laboratory confirmation. Take blood before the first dose where possible.

• Whole blood thiamine diphosphate (usual range about 70 to 180 nmol/L; low in deficiency) or erythrocyte transketolase activity coefficient (over 1.25 supports deficiency).
• Lactate, blood gas, glucose, electrolytes, magnesium, phosphate, creatinine, liver tests, full blood count, TSH.
• ECG: sinus tachycardia, prolonged QT, low voltage, T-wave inversion.
• Echocardiography: dilated right ventricle and often left ventricle, with preserved or reduced ejection fraction and high cardiac output.
• Right heart catheterisation (if done): high cardiac output, low systemic vascular resistance, raised right atrial and pulmonary artery pressures.
• Response within 24 to 48 hours (fall in heart rate and cardiac output, rise in blood pressure, diuresis) supports the diagnosis.

Differential diagnosis.

• Other high output states: thyrotoxicosis, severe anaemia, arteriovenous fistula, Paget disease, sepsis, liver disease and pregnancy.
• Dilated cardiomyopathy, alcoholic cardiomyopathy and peripartum cardiomyopathy.
• Pulmonary hypertension and constrictive pericarditis.

Thiamine (emergency).

• Moderate to severe cardiac beriberi: thiamine 100 to 200 mg intravenously (diluted in 50 to 100 mL of saline over 30 minutes) once to three times daily for 3 to 7 days, then 100 mg orally three times daily until recovery, then 50 to 100 mg daily.
• Shoshin beriberi or Wernicke features: thiamine 500 mg intravenously over 30 minutes three times daily for 2 to 3 days, then 250 mg intravenously or intramuscularly daily for 3 to 5 days, then oral therapy. Maximum single doses and duration are directed by response.
• Give thiamine before or with any glucose infusion. Resuscitation facilities should be available because anaphylaxis, though rare, is reported with parenteral thiamine.
• No dose adjustment for renal or hepatic impairment. Dialysis removes thiamine, so dose after sessions.

Supportive treatment.

• Magnesium: correct low magnesium (magnesium sulfate 2 g intravenously over 20 minutes then repeat to keep serum magnesium over 0.8 mmol/L) because thiamine dependent enzymes need it.
• Hypotension and shock: noradrenaline 0.05 to 0.5 microgram/kg/min to restore mean arterial pressure over 65 mmHg. Inotropes add little because output is already high in most cases.
• Severe acidosis (pH under 7.1 with failing compensation): sodium bicarbonate 50 to 100 mmol intravenously over 30 minutes with blood gas review; the main treatment is thiamine.
• Congestion: furosemide 20 to 40 mg intravenously, repeated by response; use cautiously because diuretics deplete thiamine and worsen hypovolaemia in shock.
• Vasodilators are not used while vascular resistance is low.
• Nutritional rehabilitation with multivitamins, protein and calories, introduced gradually to avoid refeeding syndrome (with phosphate, potassium and magnesium monitored daily for the first week). Stop alcohol.
• Mechanical circulatory support in refractory shock.

Monitoring. Heart rate, blood pressure, lactate every 2 to 4 hours in shock, daily electrolytes, magnesium and phosphate, echocardiography at 1 to 2 weeks and at 3 months. Ejection fraction usually improves within days to weeks.

Referral and escalation. Admit all patients with heart failure and suspected thiamine deficiency. Intensive care for Shoshin beriberi (hypotension with lactate over 5 mmol/L, or shock). Give high dose thiamine without delay for confusion, ophthalmoplegia or ataxia (Wernicke encephalopathy), and watch closely for rapid worsening after glucose, parenteral nutrition or refeeding. Involve nutrition, addiction and social services.

Special groups.

• Pregnancy: hyperemesis is a cause; thiamine 100 mg intravenously daily with early parenteral supplementation.
• Bariatric surgery patients: lifelong multivitamin with thiamine at least 12 mg daily (more after complications such as vomiting).
• Children: infantile beriberi occurs in breastfed infants of deficient mothers, with acute heart failure, aphonia and shock; treat with thiamine 10 to 25 mg intravenously daily and treat the mother.
• Region specific: polished rice, cassava predominant diets and food insecurity are important causes.