Which Drug Types are Used to Treat ArrhythmiaAugust 17, 2020
Under normal conditions, the heart contracts rhythmically in a healthy person. The rhythm is produces by excitation processes that periodically occur in the heart muscle itself, causing contractions of the atria and ventricles in a certain sequence and constituting the above-described cycle of the heart.
A heart rhythm disorder is called arrhythmia — there are many types of this disorder. The frequency, sequence or strength of the contractions may vary. Too rare contractions of the heart (less than 60 per minute) are called bradycardia, and too frequent (more than 100 per minute) are known as tachycardia. There are also two types of arrhythmia depending on where is the excitation center localized, namely supraventricular (atrial) and ventricular arrhythmia.
It is not always possible to understand the cause of the disease clearly, because there can be many such reasons. Arrhythmia can develop after myocardial infarction, when damage to the heart muscle makes it difficult for the impulses to occur normally. More than 80% of patients with acute myocardial infarction develop arrhythmia. The disorder can be caused by a disruption of mineral metabolism — potassium, magnesium, calcium, and sodium, which play an important role in occurrence and propagation of electrical impulses in the heart. Certain drugs, such as cardiac glycosides, can also cause arrhythmia. Violations of the nervous regulation of heart function can contribute to the development of arrhythmia. If the disease threatens the health and in some cases the life of the patient, medications are prescribed to help reduce its manifestations.
Arrhythmia symptoms can include too slow or too frequent heartbeat; missed or extra heart beats; frequent fatigue, general malaise and weakness, shortness of breath, pain in the heart.
Types of Arrhythmia Drugs
Most of the existing antiarrhythmic drugs can be divided into three main groups according to the prevailing mechanism of action. A list of drugs commonly used to treat arrhythmia includes diltiazem, amiodarone, sotalol, and metoprolol. All the drugs are available from physical and digital retailers; My Canadian Drugstore is one such example of a reasonably-priced vendor where popular drugs retail with benefits of bonus pills, shipping deals and additional discounts.
- Medicines that reduce the flow of sodium ions into the heart cells
The emergence and propagation of electrical impulses in heart cells is associated with the activity of ion channels, among which the sodium channel plays a special role. Substances that block these channels stabilize cell membranes (they are also called membrane-stabilizing) and prevent the abnormal occurrence and propagation of electrical impulses. A malfunctioning cell becomes electrically “silent”, while the activity of normal cells does not change. However, when the dose is increased, these substances suppress the conduction of the impulse in normal tissues, provoking arrhythmia. Moreover, even the therapeutic concentration of the drug can cause frequent heartbeats, acidosis, or hyperkalemia.
The progenitor of this drug group is quinidine, which is a derivative of quinine, an alkaloid of the cinchona bark. It also includes procainamide, disopyramide, lidocaine, mexiletine, moricizine, propafenone and others. They all have the same mechanism of action, similar to the action of local anesthetics, which block sodium channels inside the cell.
- Medicines that block beta-adrenergic receptors
Beta agonists, along with other pharmacological properties, can reduce the excitability of the heart. Cardiovascular functions are regulated by the autonomic nervous system, in particular by its sympathetic division, with the participation of chemical mediators that transmit impulses from one nerve cell to another. Stress, excitement, and physical work stimulate the production of these mediators, and they, in turn, excite the receptors of the heart, causing a response to the body’s increasing demand for oxygen. By blocking beta receptors in heart cells, beta agonists alter their response to a number of mediators collectively called catecholamines. As a result, the influence of these mediators on the heart is eliminated, excitability and heart rate decrease, and the rhythm is normalized.
- Medicines that block calcium channels
Channels in cell membranes, through which calcium ions move into and out of the cell, as well as other ion channels, are involved in regulating the frequency and intensity of electrical impulses that occur in the cell. Calcium channel blockers prevent the transport of calcium ions into the cell and, thereby, slow down the conduction of electrical impulses. This leads to inhibition of the sinoatrial node (cardiac pacemaker) and consequently to a reduction in contractions. Verapamil and diltiazem have the most distinct antiarrhythmic properties among calcium channel blockers.
In addition to the above, there are other drugs that have antiarrhythmic properties, but exhibit them due to different mechanisms of action. For example, amiodarone combines the properties of a beta agonist, sodium and calcium channel blocker, but in addition also blocks potassium channels. A decrease in the excretion of potassium ions from cells leads to a slowdown or cessation of pulse generation. As a result, the period of decreased excitability of myocardial cells is lengthened, and fluctuations in the membrane potential that underlie the propagation of excitation are weakened. Excitability and conduction of the heart muscle are inhibited, heart contractions are reduced, and the rhythm is restored.
Potassium drugs are also used for arrhythmia. They increase the concentration of extracellular potassium, which inhibits its release from cells and, thus, the emergence and conduction of electrical impulses.
Diagnosis and treatment of arrhythmia
Since there are various types of arrhythmia, the treatment, required drugs and procedures may also vary. Though not all arrhythmias can be completely treated, many can.
Arrhythmia diagnostics allows to examine the patient’s condition, determine the type of arrhythmia and prescribe the most effective treatment methods. In order to understand how to treat cardiac arrhythmia, the doctor must thoroughly examine the patient. Currently, the following diagnostic methods are used:
- general examination, asking the patient about seizures and symptoms;
- heart electrocardiography;
- ECG during physical exertion;
- ECG monitoring during the day;
- Echocardiogram (cardiac ultrasound);
- biochemical blood and urine analysis;
- hormonal tests.
After the necessary diagnostics are carried out, arrhythmia treatment can begin. The initial task of the treatment is to eliminate unpleasant feelings, and then to strengthen the vascular system.