under contract means there is an offer on it already and the buyer and seller are negotiating back and forth to come to an agreement. if ya need any more help just e-mail me. Lori lspalletta Â· 1 decade ago
Premature atrial complexes are caused by abnormal electrical impulses transmitted by the atria (either of the upper chambers of the heart). The abnormal electrical impulses cause contractions of the upper chamber of the heart earlier than expected. Such premature beats are generally harmless. slide 1 of 7.
A ventricular premature beat is an extra heartbeat caused by an abnormal electrical impulse starting in the lower chambers of the heart (the ventricles) before a normal heartbeat would occur. It is also known as a ventricular ectopic beat or a premature ventricular contraction.This is a form of arrhythmia that is similar to an atrial ectopic heartbeat. But where that affects the upper chambers of the heart (the atria), this affects the ventricles (or lower chambers of the heart). ventricular premature beat is an extra heartbeat caused by an abnormal electrical impulse starting in the lower chambers of the heart (the ventricles) before a normal heartbeat would occur. It is also known as a ventricular ectopic beat or a premature ventricular contraction.