Kontraktilität

Kontraktilität refers to the inherent ability of muscle tissue to shorten forcefully. This property is crucial for movement in animals and for the functioning of internal organs in many organisms. In the context of cardiac muscle, kontraktilität specifically describes the force of contraction at a given end-diastolic volume. It is an intrinsic property of the heart muscle itself, meaning it can change independently of preload and afterload, although these factors significantly influence overall cardiac output.

Several factors can influence kontraktilität. Sympathetic nervous system stimulation, through the release of norepinephrine and epinephrine, increases the force and speed of myocardial contraction. Hormones like thyroid hormone can also enhance kontraktilität. Conversely, certain medications, such as beta-blockers, can decrease it. Conditions that impair oxygen supply to the heart muscle, like ischemia, or damage to the muscle itself, such as in myocardial infarction, will also reduce kontraktilität.

Measuring kontraktilität is complex as it's an intrinsic property and difficult to isolate from preload and afterload in a living organism. However, in experimental settings, it can be assessed through various hemodynamic parameters. Understanding kontraktilität is vital in cardiology for diagnosing and managing heart failure and other cardiovascular diseases. It represents the heart's power to pump blood effectively.