Figure 9c. Ventricular perforation by a pacemaker electrode in a 66-year-old woman with acute retrosternal pain, dyspnea, and tachycardia during pacemaker implantation. (a) Axial thin-slab MIP image shows the tip of one pacemaker electrode outside the heart (arrowhead), whereas the other electrode is in a normal position in the left ventricle (arrow). (b) Coronal thin-slab MIP image shows that one electrode is in the correct location, whereas the other electrode has perforated the floor of the right ventricle (arrow). (c) Coronal volume rendered image shows the tip of the perforating electrode. Note the pronounced artifacts due to cardiac motion, which are one of the disadvantages of non-electrocardiographically gated CT.