Anorexia nervosa is a serious eating disorder characterized by severe restriction of food intake, leading to significantly low body weight. This condition profoundly impacts nearly every organ system in the body. Among the most serious physical consequences are those affecting the cardiovascular system, which can be life-threatening.
How Malnutrition Affects Heart Function
The body responds to prolonged starvation by conserving energy, slowing down non-essential physiological processes. This mechanism directly impacts the heart, leading to a reduced heart rate, known as bradycardia. Blood pressure also decreases, resulting in hypotension, as the body attempts to lower its overall metabolic demand. These changes reflect the heart’s struggle to maintain function in a state of extreme energy deficit.
Prolonged nutritional deprivation also causes the heart muscle to atrophy. The heart shrinks in size and loses mass due to the lack of protein and energy substrates. This reduction in muscle mass diminishes the heart’s pumping strength, making it less efficient at circulating blood throughout the body.
Electrolyte Imbalances and Electrical Instability
Beyond the physical changes to the heart muscle, malnutrition, particularly when coupled with purging behaviors like vomiting or laxative misuse, disrupts the body’s electrolyte balance. Minerals such as potassium, magnesium, and phosphate are depleted. These electrolytes are essential for the heart’s electrical system, which dictates the rhythm and regularity of heartbeats.
Potassium, for instance, is necessary for nerve and muscle cell function, including the electrical impulses that trigger heart contractions. Magnesium helps regulate potassium and calcium transport, which are also involved in electrical signaling. Phosphate plays a role in energy production and cell membrane integrity, indirectly influencing electrical stability. When these minerals are in short supply, the heart’s electrical signals can become erratic, leading to various types of arrhythmias. These electrical disturbances can range from relatively benign to life-threatening, with serious arrhythmias being a leading cause of sudden cardiac death in individuals with anorexia.
The Risks of Refeeding Syndrome
A dangerous complication arises during the initial stages of nutritional rehabilitation, known as refeeding syndrome. When a severely malnourished individual begins to consume food again, rapid shifts in metabolism occur. The reintroduction of carbohydrates stimulates insulin release, which drives electrolytes like phosphate, potassium, and magnesium into cells. This rapid intracellular shift can lead to low levels of these electrolytes in the bloodstream.
The sudden depletion of these minerals, combined with fluid shifts, places significant stress on an already weakened heart. This metabolic imbalance can overwhelm the cardiovascular system, causing acute heart failure, where the heart cannot pump enough blood to meet the body’s needs. Refeeding syndrome can also lead to respiratory failure and, in severe cases, death. Because of these significant risks, nutritional rehabilitation for individuals with severe anorexia must be conducted under careful medical supervision, often beginning with small, frequent feedings and close monitoring of electrolyte levels.
Cardiac Recovery and Prognosis
Many of the cardiovascular complications associated with anorexia nervosa, such as bradycardia and the reduction in heart muscle mass, can be reversible with sustained nutritional rehabilitation and weight restoration. As an individual regains weight and consistently consumes adequate nutrients, the heart can begin to rebuild its muscle mass and improve its pumping efficiency. The heart rate normalizes, and blood pressure returns to a healthier range as the body’s metabolic demands are met.
However, the recovery of heart function can lag behind initial weight gain. While significant improvement is common, some individuals may experience a persistently increased risk for cardiac events, even after reaching a healthy weight. This can be due to long-term structural changes or residual damage from prolonged malnutrition. Therefore, long-term medical monitoring, including regular cardiovascular assessments, remains important even after weight restoration to ensure the heart has fully healed and to address any lingering cardiac vulnerabilities.