Temporary wires are routinely sutured to atrial and/or ventricular epimyocardium after open heart surgery. Despite the common problems of poor sensing or capture, dislodgement or retention, no criteria exists for proper placement or removal. This report describes clinical complications due to: failure of ventricular sensing, failure of ventricular capture, bleeding from right ventricular laceration with tamponade, avulsion of a side branch from a saphenous vein coronary bypass graft, and perforation of the superior epigastric artery. Appropriate placement of temporary wires for optimum function requires 2-cm electrode separation, application into both atrium and ventricle with a gentle redundant loop to exit near the midline, avoiding both coronary arteries and coronary artery bypass grafts. Gentle traction for removal is recommended on the day prior to discharge, especially for patients on antiplatelet or anticoagulant therapy.