What does "re-entry" refer to in the context of dysrhythmias?

"Re-entry" in the context of dysrhythmias specifically refers to a phenomenon where an electrical impulse travels along a circuitous pathway within the heart tissue. This occurs when a single impulse encounters a region of tissue that is partially depolarized, allowing the impulse to loop back and re-excite the myocardial tissue that it has already stimulated.

This mechanism can result in sustained dysrhythmias, such as atrial flutter or certain types of ventricular tachycardia, because the re-entering impulse can cause rapid and repetitive activation of the heart muscle. The essential feature of re-entry is that it requires a circuit, which is often facilitated by changes in conduction velocity and refractoriness in the heart.

This concept is critical in understanding various arrhythmias and their treatments, as addressing the underlying re-entry circuit can effectively restore normal heart rhythm.