Pharmacology of the heart : Arrhythmia
A healthy heart beats 60 – 100 times per minute. Arrhythmias are anomalies of the heartbeat. A lower heart frequency is known as bradycardia, a higher one as tachycardia. Not just a deviation of the normal frequency, but also irregularities of the heart beat can occur. However, an arrhythmia does not have to be necessarily dangerous. If arrhythmias burden the patient, restrict their performance or even prevent the blood supply, a professional treatment is needed and has to be conducted by a physician.
In order to understand the antiarrhythmic therapy, the patient has to understand the cardiac activity to a certain extent. The heartbeat, which is finally pumping the blood through our body, is a result of electric stimuli pervading through the heart. These stimuli are causing contractions of the heart muscle and with that the pumping motion.
This electric stimuli, called cardiac action potential, is mostly generated by the ions sodium, potassium and calcium by passing through the membranes of the heart cells (In order to generate continuous heart actions, our body is in possession of ion pumps and transporter to put the ions in the basic position).
Pathology and Therapy
A heart frequency above 100 times/minute (tachycardia) and lower 60 times/minute (bradycardia), as well as an irregular heart beat (e.g. an extra heart contraction) are considered pathologic.
Depending on which type, localization and the degree of disturbance, a certain therapy has to be taken into account.
The following gives an overview about the pharmaceutical drugs, used in the treatment of arrhythmia. The main target for these therapies are the ions, which are responsible for the electric stimulus. By blocking their channels and therefore influencing their pathways, it is possible to achieve a partial recovery. On the other side, the use of heart medication can be a risk, especially when taken incorrectly. For this purpose, patients need to be aware and listen to advices given by the physician and pharmacist.
The group of anti-arrhythmics are subdivided in four groups:
- Type I (Sodiumchannel blocker)
- Type II (b-adrenergic blocker / Betablocker)
- Type III (Potassiumchannel blocker)
- Type IV (Calciumchannel blocker)
Each group targets a different ion channel and can help to stabilize the heart rhythm. Depending on severity, co-medication or other circumstances like pregnancy, different therapies can be conducted. The following drug profiles shall provide the most important facts the patient must know, if the respective drug is part of the treatment:
Author: Simko Sama (KEMSA IT Manager)
Arzneimittelprofile 4th edition , Deutscher Apotheker Verlag