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.
Premature atrial complexes, or PACs, are âextraâ heartbeats that arise within the atria of the heart. PACs are the most common variety of heart arrhythmia. In fact, PACs are so common that most people will have them occasionally.