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.
Then there's usually a pause that causes the next beat to be more forceful. You felt this more-forceful beat. Types of premature contractions. Premature atrial contractions (PACs) start in the upper chambers of the heart (atria). Premature ventricular contractions (PVCs) start in the lower chambers of the heart (ventricles).