Reizleitungssystem

The **Reizleitungssystem** (German for conduction system) is a specialized network of electrically excitable cells within the heart that coordinates the rhythmic contraction of cardiac muscle. It ensures synchronized electrical activity, allowing the heart to pump blood efficiently through the circulatory system. The system is composed of several key structures, each playing a distinct role in maintaining cardiac rhythm and function.

At the center of the conduction system is the **sinus node**, located in the right atrium near the superior vena cava. This node, often referred to as the natural pacemaker, generates electrical impulses at a regular interval, typically between 60 and 100 beats per minute in a healthy adult. These impulses travel through specialized conduction fibers to initiate atrial contraction.

From the sinus node, impulses propagate to the **atrioventricular (AV) node**, situated in the interatrial septum near the coronary sinus. The AV node acts as a delay mechanism, allowing the atria to contract fully before the impulses reach the ventricles. From here, the conduction system branches into the **bundle of His**, which descends through the fibrous skeleton of the heart into the ventricles.

The bundle of His divides into two main branches, the **left and right bundle branches**, which further subdivide into smaller fibers known as **Purkinje fibers**. These fibers spread throughout the ventricular myocardium, ensuring rapid and uniform depolarization of the ventricular muscle. This coordinated depolarization results in synchronized ventricular contraction, which drives blood into the aorta and pulmonary arteries.

Disruptions in the conduction system can lead to various cardiac arrhythmias, including bradycardia (slow heart rate), tachycardia (rapid heart rate), or conduction blocks. Conditions such as heart block, Wolff-Parkinson-White syndrome, or myocardial infarction may impair signal transmission, requiring medical intervention. Understanding the conduction system is fundamental to diagnosing and managing cardiac disorders.