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 graph architecture Node graph architecture Node graph architecture is a type of software design which builds around modular node components which can be connected to form a graph. Often the software's underlying node graph architecture is also exposed to the end user as a two-dimensional visualization of the node graph. The node graph architecture is popular in the film and computer games industry. There are often many different node types participating in the node graph. For example, in the Nuke Manual they list hundreds of nodes. Each node type performs one specific task. For example, Nuke's Merge node produces an output image