Cardiotonic drugs are drugs that enhance the activity of the heart muscle, its contractility and are used in the treatment of heart failure. The group includes a significant number of drugs having various active substances in the composition and a different mechanism of action. Cardiotonics are used to treat acute and chronic heart failure.
Cardiotonic drugs: classification
The overall effect of all drugs in the group is based on the ability to increase the strength of myocardial contractions, resulting in increased cardiac output and stroke volume. Cardiotonic drugs reduce diastolic volume, pulmonary and systemic pressure in the veins, as well as pressure when filling the ventricles.
- Cardiac glycosides - "Strofantin", "Korglikon", "Digoxin".
- Adrenergic drugs - Isadrin, Dobutamine, Dopamine.
- Nonadrenergic synthetic drugs - Amrinon, Milrinon.
The choice of drugs used is associated with the severity of the patient's condition and the form of the course of the disease.
Cardiac Glycosides
The group is represented by herbal or synthetic products. Preparations based on plant substances were obtained from digitalis, adonis, spring lily of the valley, oleander, strophanthus, etc.
The duration of the therapeutic effect, the effect of accumulation in the body and the neurotoxicity of drugs completely depend on their ability to form complexes with blood plasma proteins. The stronger the bond, the higher the efficiency of the glycoside. Cardiotonic agents of this group have an effect based on the following mechanisms:
- there is a shortening of systole with its simultaneous strengthening;
- the resting period of the heart muscle lengthens;
- heart rate decreases;
- increased ability of the myocardial muscle to arousal;
- with an overdose of drugs, ventricular arrhythmia develops.
"Digoxin"
The drug is synthesized from digitalis leaves. Refers to long-acting glycosides that do not give serious side effects. It is used for the complex treatment of chronic heart failure and tachysystolic arrhythmia.
Available in the form of tablets and injection. The dose must be selected carefully, for each patient individually. If other cardiac glycosides are used before Digoxin, the dosage is reduced.
Strofantin
It is a short-acting cardiac glycoside used in case of acute form of insufficiency. "Strophanthin" does not tend to accumulate in the body. The drug enhances the contractile function of the myocardium and increases the minute volume of blood. In parallel, there is a reduction in the size of the heart muscle and a decrease in its oxygen demand.
It is used intravenously, intramuscularly, in some cases - inside. Taking large amounts can lead to an overdose. Application with other drugs changes the effectiveness of the action of glycoside:
- with barbiturates, the effect is reduced;
- with "Reserpine", sympathomimetics and antidepressants can cause the development of cardiac arrhythmias;
- admission with tetracyclines, “Levomycetin”, “Amiodarone” and “Captopril” enhances the cardiotonic effect;
- magnesium sulfate contributes to the development of cardiac atrioventricular block.
Adrenergic drugs
Non-glycoside cardiotonic agents with a short-term effect. The group is used in acute heart failure to support important body functions.
"Isadrin" is a stimulant of adrenergic receptors of blood vessels, bronchi and the heart. The drug has a hypotensive effect, strengthens the contractility of the heart muscle. It is used in cardiac surgery with a sharp decrease in contractility during surgery, as well as in cardiogenic shock. Reviews of doctors warn: improper use or oversizing can cause fibrillation of the ventricles of the heart.
“Dobutamine” is a cardiotonic agent of a non-glycosidic structure, which has a stimulating effect on the heart muscle, and also normalizes coronary blood flow. The risk of developing arrhythmias when using this agent is quite low, since Dobutamine has practically no effect on cardiac automatism.
It is prescribed, if necessary, to strengthen the contractility of the myocardium. In some cases, it can cause the development of side effects:
- nausea;
- headache;
- hypertension
- increased heart rate;
- pain behind the sternum.
"Dopamine" is a catecholamine that stimulates adrenergic receptors. The drug increases blood pressure, enhances coronary blood flow. It is prescribed for acute myocardial failure, shock. Caution should be used for myocardial infarction, pregnancy, thyroid disease, arrhythmias.
Nonadrenergic Synthetic Cardiotonics
These are cardiotonic agents used in case of acute coronary insufficiency . The drugs act on the contractility of the heart muscle, strengthening it. They can provoke the development of arrhythmia and a decrease in blood pressure, impaired renal function.
Cardiotonic drugs of this group cannot be used for heart defects, as well as cardiomyopathy, cardiac arrhythmias, aortic aneurysm, kidney failure, heart attack, and during the period of gestation.
Amrinon is used exclusively in intensive care units, so that the patient is constantly under the control of special devices that signal his condition. In addition to strengthening heart contractions, the drug dilates blood vessels, increases blood flow during systole, and reduces pulmonary pressure.
Available in the form of a solution. For intravenous administration, it is diluted exclusively in physiological solution of sodium chloride. Do not mix with other medications. With the introduction of a possible sharp decrease in pressure, increased heart rate, arrhythmia, the appearance of headache, gastrointestinal disorders.
Milrinon is more active than the first representative of the group, and according to reviews it is better tolerated by patients. The use of the drug in pregnancy and the development of myocardial infarction is contraindicated. It belongs to the drugs of group A. The need for the use of the drug is determined solely by the doctor.
Conclusion
Cardiotonic agents have proven effective several generations ago. Reviews indicate that drugs in this group help to cope with heart failure. However, taking such medications in the form of self-medication is strictly contraindicated due to the development of possible complications, side effects or overdose. The choice of drug, as well as the dose, is determined by the cardiologist in each clinical case individually.