The function of your heart as a pump is dependent on the movement of calcium ions into cardiac cells. It is therefore reasonable to believe that taking calcium supplements may impact heart function, particularly in a patient with heart disease. A number of studies have investigated the impact of calcium supplements on the efficacy of medications used in the treatment of atrial fibrillation and have provided insight into the relationship between this cardiac condition and dietary calcium supplements. Consult with your doctor when considering adding supplements to your diet.
Heart Physiology
To understand the pathology of atrial fibrillation, you must have a clear picture of normal heart function. The process of heart contraction normally begins in a bundle of specialized cells known as the sino-atrial node, or SA node. This structure generates an electrical signal autonomously, acting as the master regulator of cardiac contraction. Next, the electrical signal is conducted to the surrounding heart muscle tissue, propagating itself through the first pair of chambers in the heart, known as the atria. As the left and right atria are forced to contract, blood is pumped downward into the second pair of chambers, or the ventricles. This region of the heart is responsible for pumping blood throughout your entire body. Consequently, the ventricles are much larger and more muscular than the atria. Just as the last drops of blood are transferred to the ventricles, the electrical signal is conducted through a second specialized group of cells, known as the atrio-ventricular node, or AV node. The AV node, located between the atria and ventricles, serves a vital function in coordinating the movement of blood through the heart; these cells will prevent the electrical signal from initiating ventricular contraction until the atria have fully emptied their contents into the ventricles. This mechanism of coordination, which normally allows for efficient circulation of blood through the heart, is disrupted in severe cases of atrial fibrillation.
Atrial Fibrillation
One of the most common heart conditions in elderly patients is atrial fibrillation, or AF. According to the National Heart, Lung and Blood Institute, AF is characterized by rapid, disorganized electrical signals in the atria, causing these chambers to fibrillate, or contract in a fast, irregular pattern. When the atria are contracting in this erratic, unregulated fashion, blood will not flow smoothly through the heart. Additionally, electrical signals from the atria may inappropriately propagate into the ventricles, leading to a similarly rapid, uncontrolled pattern of contraction in these larger, more important heart chambers. While patients may experience AF on a chronic basis with minimal symptoms, the consequences of this condition can be disastrous when the ventricles become affected. Therefore, the primary goal of treatment for atrial fibrillation is to prevent the conduction of the erratic, rapid electrical signals through the AV node and into the ventricles.
Treatment
AF is commonly treated with a class of medications known as calcium-channel blockers. These drugs act to inhibit the movement of calcium ions into heart cells, attenuating the strength and rate of heart contraction. This is an effective treatment strategy in patients with AF; by slowing the rate of electrical excitation in the SA node, the atria are less prone to contract in the dangerous, uncontrolled manner that is characteristic of this syndrome. Additionally, these medications are known to act on the AV node to prevent the electrical signals from inappropriately propagating into the ventricles where they can produce ventricular tachycardia, or rapid heart beats.
Calcium Salt Studies
The interaction of calcium supplements with the function of calcium-channel blockers has been investigated in several clinical studies. According to a May 2000 article from the journal "Annals of Pharmacotherapy," calcium supplements given before treatment with intravenous verapamil, a calcium-channel blocker, are effective in preventing dangerous side effects of the medication, which include hypotension, or low blood pressure. The anti-arrhythmic effects of verapamil were not affected by calcium supplements, suggesting this combination as a useful strategy for managing AF while minimizing its hypotensive side effects. In other words, calcium supplements do not appear to have significant negative effects on patients with atrial fibrillation and may in fact show benefits when combined with other anti-arrhythmic medications.
References
- Drug-Drug Interactions: Calcium Supplements/Calcium Channel Blockers
- "Annals of Internal Medicine"; Intraveneous Verapamil for Treatment of Multifocal Atrial Tachycardia With and Without Calcium Pretreatment; Salerno D.M., Anderson B., Sharkey P.J., and Iber C.; 1987
- PubMed Health; Verapamil; August 2010
- "Annals of Pharmacotherapy"; The Use of Calcium Salts in the Prevention and Management of Verapamil-induced Hypotension; Moser L.R., Smythe M.A., and Tisdale J.E.; May 2000
- "American Heart Journal"; Pharmacologic Management of Atrial Fibrillation: Current Therapeutic Strategies; Levy S.; 2001
- National Heart, Lung and Blood Institute: What is Atrial Fibrillation?
