How does malnutrition cause chest pain and palpitations?

Mechanisms of Chest Pain and Palpitations in Malnutrition

Malnutrition can cause chest pain and palpitations through multiple pathophysiological mechanisms including cardiac muscle atrophy, electrolyte disturbances, and autonomic dysfunction. 1

Cardiac Mechanisms

Cardiac Muscle Changes

• Cardiac muscle atrophy: Malnutrition causes proportional loss of both skeletal and cardiac muscle, reducing myocardial mass and the heart's ability to generate adequate cardiac output 2
• Cardiac cachexia: In severe cases, malnutrition leads to cardiac cachexia, creating a vicious cycle where heart failure worsens cardiac function 1
• Structural changes: Prolonged starvation can cause anatomical abnormalities including cardiac muscle atrophy and pericardial effusions 3

Electrophysiological Disturbances

• Electrolyte imbalances: Potassium depletion from malnutrition can produce:
  • Disturbances in cardiac rhythm (primarily ectopic beats)
  • Prominent U-waves on electrocardiogram
  • Palpitations and arrhythmias 4
• QTc prolongation: Malnutrition, especially with rapid weight loss, causes prolongation of the QTc interval, increasing risk of arrhythmias 3
• Bradycardia: Chronic starvation often leads to sinus bradycardia, which can cause compensatory palpitations when activity increases 3

Chest Wall and Respiratory Mechanisms

• Diaphragmatic fatigue: Malnutrition causes respiratory muscle weakness leading to diaphragmatic fatigue and chest wall pain 1
• Altered chest wall mechanics: Poor nutrition leads to delayed lung and chest wall development, resulting in altered mechanics and pain 1
• Musculoskeletal causes: Malnutrition exacerbates musculoskeletal causes of chest wall pain, leading to chest wall syndrome 1

Systemic and Metabolic Effects

• Inflammatory response: Malnutrition is associated with increased inflammatory markers and oxidative stress, which can sensitize pain receptors in the chest wall 1
• Autonomic dysfunction: Nutritional deficiencies affect autonomic nervous system function, leading to inappropriate heart rate responses and palpitations
• Metabolic alkalosis: Potassium depletion is often accompanied by metabolic alkalosis, which can trigger cardiac arrhythmias 4

Gastrointestinal Contributions

• Gastroesophageal reflux: Pulmonary hyperinflation from respiratory muscle weakness can affect lower esophageal sphincter function, leading to reflux that causes chest pain 1
• Esophageal pain: Malnutrition can exacerbate esophageal sensitivity, causing chest pain that mimics cardiac pain 1

Clinical Implications and Management

• Nutritional assessment should be performed in all patients with unexplained chest pain and palpitations 1
• Malnutrition is present in approximately 17% of patients with heart failure and is independently associated with increased mortality 5, 6
• Refeeding must be done cautiously as the "refeeding syndrome" can trigger cardiac complications, especially in severely malnourished patients (less than 70% ideal body weight) 3
• Extremely low-calorie diets should be avoided as they have been reported to cause cardiac arrhythmias and sudden cardiac death 3

Monitoring and Prevention

• Regular screening for electrolyte abnormalities, particularly potassium, is essential in malnourished patients 4
• ECG monitoring for QTc prolongation is important, especially in patients with anorexia nervosa or rapid weight loss 3
• Most cardiac manifestations of malnutrition are reversible with appropriate nutritional rehabilitation 3

Understanding these mechanisms can help clinicians recognize and address the cardiac manifestations of malnutrition before they progress to more serious complications.