A premature atrial contraction occurs when a focus in the atrium (not the sinoatrial node) generates an action potential before the next scheduled SA node action potential. There are four main ...

A premature ventricular contraction occurs when a focus in the ventricle generates an action potential before the next scheduled sinoatrial nodal action potential. Ventricular bigeminy occurs when ...

For the purposes of this review, emphasis will be on studies of leading or top rope situations ... Rock climbing is unique from a physiological point of view because it requires sustained and ...