Medications That Reduce The Heart Rate

Physicians treat arrhythmias that cause the heart to beat too fast and irregularly with medications that slow the heart rate by delaying electrical impulses in the heart. Medications that reduce the heart rate work by affecting the movement of electrolytes like calcium and potassium in and out of cardiac cells. Interfering with these electrolytes alters the cardiac conduction system. Following prescribed dosing regimens can successfully and safely reduce the heart rate.

Cardiac Glycosides

The Digitalis lanata plant produces a commonly used cardiac glycoside called digoxin. Physicians prescribe digoxin to treat irregular heart rhythms such as atrial fibrillation and heart conditions such as congestive heart failure. The National Institutes of Health explains how digoxin makes the heart beat slower by decreasing the speed at which signals for the heart to beat travel from the sino-atrial node in the atrium to the ventricles. Digoxin also gives the heart a stronger contraction, which improves blood flow to the body.
Patients taking digoxin should be aware of dangerous adverse reactions. The pulse must be measured for one minute before taking digoxin. Billie Ann Wilson, PhD., Margaret Shannon, PhD., and Kelly Shields PharmD., authors of "Pearson Nurse's Drug Guide 2010" explain if a patient's heart rate falls outside of the prescribing physician's parameters, for example below 50 beats per minute, the patient holds the dose of digoxin and notifies the physician.
Blood levels of digoxin can become too high causing toxicity. Symptoms are nausea, vomiting, diarrhea, visual disturbances and an irregular heart rate and rhythm. Too much digoxin can cause a condition called atrioventricular heart block. With AV block the signal for the heart to beat does not reach the ventricles so the heart can stop beating.

Beta Blockers

Beta blockers slow the heart rate by blocking certain receptor sites, called beta-adrenergic receptors, in the heart muscle. This action, called a negative inotropic action, slows the heart rate. Atenolol and metoprolol are examples of commonly prescribed beta blockers. Many beta blocker drug names end in "lol" which makes for easy recognition. Physicians use beta blockers to treat patients with high blood pressure, angina and heart attack. Slowing the heart rate has the added benefit of lowering blood pressure. Both of these actions decrease the work load on the heart. Beta blockers have the potential to significantly decrease the heart rate. Patients should measure the pulse for one minute before taking a beta blocker and report a heart rate below 60 beats per minute to the prescribing physician. The beta blocker should be held unless instructed otherwise.

Calcium Channel Blockers

Verapamil and diltiazem are two examples of calcium channel blocker drugs used to control heart rate. A calcium channel blocker slows the rate of calcium ion transport across cardiac cell membranes. This action slows the rate of electrical impulse conduction in the heart, causing a slower heart rate. There are many other calcium channel blockers used primarily for lowering blood pressure, because these drugs cause vasodilation or relaxation of arteries. Low blood pressure can be problematic for patients, especially when beginning drug therapy. Patients should monitor blood pressure daily and report symptoms of dizziness and fatigue to the prescribing physician. The dose of the calcium channel blocker may need to be adjusted to alleviate low blood pressure.