Premature atrial contraction the atrioventricular (AV) node, the signal is conducted both to the ventricle and back to the SA node where the signal began. Premature atrial contraction Premature atrial contractions (PACs), also known as atrial premature complexes (APC) or atrial premature beats (APB), are a common cardiac dysrhythmia characterized by premature heartbeats originating in the atria. While the sinoatrial node typically regulates the heartbeat during normal sinus rhythm, PACs occur when another region of the atria depolarizes before the sinoatrial node and thus triggers a premature heartbeat. The exact cause of PACs is unclear; while several predisposing conditions exist, PACs commonly occur
Node (Well of Echoes) or node-drainers that drain the node of the field and render anything that draws power from it useless. Mancers who cannot draw from a distat node's field must rely on charged crystals, while clankers, constructs and any other devices of the Art will not work. There are also rare places called anti-nodes, where the Art does not work or is at least greatly reduced. Node (Well of Echoes) Nodes are fictional, naturally occurring phenomena in Ian Irvine’s "The Three Worlds Cycle" of novels. They often occur in places where there is a significant landmark, such as on a hill or