Please choose the correct ending to complete the given sentence: Health: [header] How to identify heart blocks [title] Understand what the term " heart block " refers to. [step] The term heart block refers to an av block or an atrio-ventricular block. This is when there is some obstacle blocking electrical signals between the upper and lower chambers of the heart.

Ending1: Av blocks are a longer term term, for instance called " heart block ". [substeps] Heart block blocks are usually black, which means that there is not a hair block or an artery. Ending2: These signals are not evident on the inside of the heart block. A heart block that is present in your heart block may not be heart block but another heart block which trains the arteries in the heart muscles. Ending3: The lack of these signals is known as an av block. Av blocks are what appear to alter arteries in the heart. Ending4: [substeps] There are three degrees of av block according to severity-first degree, second degree and third degree. Second degree heart blocks have two subtypes.

Answer format: ending1/ending2/ending3/ending4