Antiarrhythmic Drugs: What Types Of Medications Are Used To Treat Irregular Heartbeats?

Arrhythmias, conditions that cause an abnormal heartbeat, can be challenging to deal with. If severe enough, they cause damage to one of the most vital organs in the body, the heart.

Not only does this make the arrhythmias with more symptoms hard to ignore, but also hard to permanently remedy without very invasive surgery that permanently changes the heart. Fortunately, there is another solution that can assist in treating most arrhythmias; medications.

Most arrhythmias aren't severe enough to require surgery, so medications are often the best solution. With proper management, medications can do a great deal towards mitigating the symptoms of arrhythmias.

What medications are used to treat arrhythmias?

Because "arrhythmia" covers many different conditions that cause an abnormal heartbeat, the variance in the type of medication depends on the condition that the patient has. For example, someone with a condition that causes a slow heartbeat may need a medication that increases how fast the heart beats. Others may require a drug that makes the heart less forceful, and so on. Below are some of the most common medications used to treat arrhythmias.

Adenosine

Adenosine is a medication that makes it more difficult for electrical signals to cause a heartbeat. Electrical signals that move throughout the heart control the heart's beats. When these electrical signals reach certain parts of the heart, it forces that part of the heart to react in a certain way, which is what allows "beats" to occur.

Adenosine slows down heartbeats by chemically requiring the heart to need stronger signals to produce a heartbeat. Adenosine deals with arrhythmias that cause the heart to beat too fast. Adenosine can also have short-lived side effects, such as lightheadedness, nausea, sweating, and nervousness.

Atropine

Atropine works oppositely to adenosine. Whereas adenosine makes it harder for electrical signals to produce a heartbeat, atropine makes it easier. It blocks chemicals that would otherwise slow down the heartbeat. Thus, atropine speeds up the heart to oppose arrhythmias that slow down the heart. Some side effects can include a dry mouth, photophobia, and blurred vision. Other side effects, such as difficulty with sweating and urination, can occur in the elderly in particular. 

Beta-blockers

Beta-blockers are named such because they block chemicals, like adrenaline, from affecting the heart. Adrenaline is a widely known stress hormone, and it also increases heart rate and blood pressure. By preventing some adrenaline from affecting the heart, a beta-blocker lowers blood pressure and heart rate. Some beta-blockers even relax blood vessels, which can lower blood pressure even further. Of course, this lends itself to treating arrhythmias that involve a fast heart rate.

Unfortunately, blocking chemicals isn't just limited to the heart, and can cause several other unintended effects across the body. Fatigue, nausea, and constipation are possible side effects of beta-blockers. Sexual dysfunction is a side effect that has also been reported but is less frequent.

Blood thinners

Blood thinners don't literally make the blood thinner, but they're a good analogy for how they actually work. Blood thinners make it more difficult for the blood to clot. This doesn't directly improve the life of someone with an arrhythmia; in daily life, it'll hardly be noticeable.

However, certain arrhythmias, such as atrial fibrillation, significantly increase the risk of cardiovascular diseases like heart attacks and strokes. Because strokes and heart attacks involve blood clots, blood thinners can help protect those with said arrhythmias from deadly cardiovascular events. The side effects of blood thinners aren't surprising; it makes the patient bleed easier in addition to making it harder for blood to clot after bleeding has started. 

Calcium channel blockers

Calcium channel blockers are very similar to beta-blockers. Calcium channel blockers prevent calcium from entering heart muscle cells, which ends up reducing how effective electrical signals are, as well as widening blood vessels. Calcium channel blockers similarly reduce blood pressure and heart rate and are used to counteract increased heart rate from certain arrhythmias. Possible side effects are headaches, lightheadedness, and constipation.

Digitalis/digoxin​

Digitalis is another drug that interacts with calcium. Unlike calcium channel blockers, digitalis increases the amount of calcium, which increases heart output. However, digitalis also interacts with electrical conductivity, making it harder for the heart to conduct electrical signals, thus slowing the heart rate. Digitalis is used for cases when the heart has been weakened or it is beating too quickly. Some of the possible side effects include vision changes, dizziness, drowsiness, or rash.

Potassium channel blockers

Unsurprisingly, potassium channel blockers work similarly to many of the other "blockers" listed. They cause the cells that produce electrical signals to take longer to "recharge," and therefore slow the heart rate. Side effects can include nausea, lightheadedness, anxiety, and insomnia.

Sodium channel blockers

Sodium channel blockers inhibit how much sodium can pass through certain cells. Sodium channel blockers are another drug that results in the heart's cells being less conducive to electrical signals and slows down the heartbeat. These should be avoided when one has heart disease as it can increase the risk of cardiac arrest.

Isoproterenol 

Isoproterenol works similarly to adrenaline and increases the heart rate and strength of heartbeats. Because it induces a quicker heartbeat, it is best used to treat arrhythmias that cause the heart to become abnormally slow. Side effects of isoproterenol can include headache, lightheadedness, nervousness, and nausea.