inotrópok

Inotropes are substances that alter the contractility of heart muscle. Positive inotropes increase the force of myocardial contraction, while negative inotropes decrease it. This effect on contractility influences the heart's ability to pump blood effectively.

The primary mechanism of action for many inotropes involves altering the intracellular concentration of calcium ions within cardiac muscle cells. Increased calcium availability during contraction generally leads to stronger muscle fiber shortening. Some inotropes achieve this by enhancing calcium influx into the cell, while others inhibit the mechanisms that remove calcium from the cell.

In clinical practice, positive inotropic agents are frequently used to manage conditions characterized by weakened heart muscle, such as heart failure. By increasing the force of contraction, these drugs can improve cardiac output, reduce blood congestion in the lungs, and alleviate symptoms like shortness of breath and fatigue. Examples of commonly used positive inotropes include digoxin, dobutamine, and milrinone. Digoxin works by inhibiting the sodium-potassium pump, leading to increased intracellular sodium and subsequently increased intracellular calcium. Dobutamine and milrinone are often administered intravenously in acute settings.

Negative inotropic agents, on the other hand, reduce the force of heart muscle contraction. These are less commonly used as primary treatments but may be employed in specific situations, such as managing certain arrhythmias or reducing myocardial oxygen demand in acute myocardial infarction. Beta-blockers and calcium channel blockers can have negative inotropic effects, though their primary indications are often for blood pressure control or rate control in arrhythmias. The use of inotropic agents requires careful monitoring due to potential side effects, including arrhythmias and increased myocardial oxygen consumption.