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.
Quick Answer. Common causes of mild left atrial enlargement can be divided into both congenital causes, like ventricular septal defect, or VSD, and patent ductus arteriosus, or PDA, and acquired causes, like mitral stenosis, mitral regurgitation, left ventricular failure and left atrial myxoma, as reported by Radiopaedia.