How is "heart block" defined?

Heart block is defined as a delay or complete block in the electrical conduction system of the heart. This condition occurs when the electrical impulses that coordinate the heartbeat are either slowed down or interrupted as they move through the heart's conduction pathways, particularly through the atrioventricular (AV) node. The severity of heart block can vary, ranging from first-degree block, which is merely a delay, to third-degree block, where the conduction is completely blocked, potentially leading to serious complications such as bradycardia or complete heart failure.

Understanding heart block is crucial in cardiac medicine since it affects the heart's ability to effectively pump blood to the rest of the body. Patients may experience symptoms such as dizziness, fatigue, palpitations, or even syncope, depending on the degree of the block. Treatment often involves the use of a pacemaker in more severe cases to regulate heartbeats effectively.

The other options represent conditions or phenomena that do not relate directly to the definition of heart block. Rapid heartbeat without warning describes tachycardia, abnormal heart size relates to cardiomyopathy or other structural heart issues, and a persistent elevated heart rate is again a separate condition known as tachycardia or a form of arrhythmia, rather than a conduction