Subclavian vein occlusion from previously implanted pacing leads is a problem that has become more of an issue as physicians attempt to upgrade existing pacing systems to either an AICD or a resynchronization device. On some occasions, a guidewire such as the Glidewire ® (Terumo Medical Corporation, Somerset, New Jersey) or Cross-It XT ® (Guidant, St. Paul, Minnesota) can be manipulated through the total occlusion. Once a guidewire is across the lesion it can be dilated with a balloon or progressively larger dilators. When a guidewire will not cross the occlusion, the operator must either extract an existing lead or move to the other side. Lead extraction has a mortality in excess of 2%, has limited availability and the remaining lead is often displaced or damaged in the process. Implantation of a cardiac resynchronization system on the right side is more difficult and defibrillation thresholds are often higher on the right. In some cases moving to the other side may not be an option due to occlusion or infection. Epicardial LV lead placement is associated with a significant morbidity and mortality and lead placement may not be ideal. A practical, generally applicable approach to the totally occluded subclavian vein is important for patient care. A 73-year-old patient with Class 4 CHF, VT, and non-ischemic cardiomyopathy ejection fraction of 17% was presented for implantation of a resynchronization device. There was no venous access on the left and an occluded subclavian vein on the right at the site of a previous pacemaker implant (Figure 1). The occluded vein segment vein was short (Figure 2). After failure to cross the occlusion with several guidewires, the patient returned to the lab for an attempt to cross the occlusion with the Frontrunner device (Figure 3). Venous access was obtained proximal to the occlusion and a 5 French (Fr) sheath was inserted up to the occlusion. The Frontrunner catheter was then advanced to the occlusion and repeatedly opened and closed to bluntly dissect along the existing pacing leads (Figure 4). Contrast was intermittently infused to confirm the Frontrunner was not extra luminal. After 5 minutes of blunt dissection with the Frontrunner, a puff of contrast revealed the collaterals were no longer apparent (Figure 5). The Frontrunner was removed and an angled Glidewire was easily manipulated across the lesion. A 6 mm x 4 cm POWERFLEXTM (Cordis Endovascular, Warren, New Jersey) balloon was then inflated at the site of the occlusion (Figure 6). A long 7 Fr sheath was passed across the occlusion, and two Amplatz (Cook, Bloomington, Indiana) extra-stiff wires were placed through the 7 Fr sheath. The sheath was then removed, and the Amplatz wires were used to insert two 9 Fr sheaths for LV lead and AICD lead placement. The procedure was completed successfully and the patient discharged home the following day. There was no damage to the existing pacing leads. A 53-year-old male with coronary artery disease and a prior pacemaker on the left, developed ventricular tachycardia and required AICD implantation. Both antegrade (Figure 7) and retrograde (Figure 8) venograms revealed a short segment total occlusion of the left subclavian vein. After an unsuccessful attempt to cross the occlusion with a variety of wires, the Frontrunner device was employed. The Frontrunner was deployed through a 6 Fr guidewire to improve directional control. The initially position of the device (Figure 9) was superior to occlusion-lead interface. Microdissection was not carried out in this area. After redirection, microdissection was conducted along the inferior aspect of the lead (Figure 10), until the tip reentered the vein distal to the occlusion (Figure 11). Contrast injection proximal to occlusion revealed a flow through the occlusion (Figure 12). A guidewire followed by a 6 mm x 4 cm balloon was advanced through the area of former occlusion and inflated to 18 atmospheres to eliminate the waist in the balloon produced by the residual stenosis (Figure 13). After microdissection and balloon dilation, the subclavian vein was patent with no evidence of loss of vascular integrity (Figure 14). The outcome of recent clinical trials has resulted in the general acceptance of cardiac resynchronization therapy and AICD implantation as valuable additions to patient care. As a result, more patients with existing leads will be presented for AICD implantation and/or upgrade to a biventricular pacing system. Many of these patients have existing left-sided systems with an occluded subclavian vein. When the left side is occluded, neither lead extraction nor implanting from the right side is a desirable option. In the case of cardiac resynchronization, both options are associated with an increased mortality; the right sided approach as a result of implant failure1 and lead extraction as a result of vascular or cardiac laceration.2 In the case of AICD s, the defibrillation thresholds may be higher on the left side. The Frontrunner CTO is designed to cross chronic, totally occluded coronary or peripheral vessels via controlled blunt microdissection that enables guidewire access to perform percutaneous intervention. We describe the first reported use of the Frontrunner CTO for blunt microdissection of a vein along an existing pacing lead to facilitate placement of a resynchronization device without damage to the existing leads. In our patients, the only options were lead extraction to create a new channel or surgical lead placement; both options associated with significant morbidity and/or mortality. Although blunt microdissection has the potential to perforate the vein, venous perforation is not likely to be a problem in a low-pressure system with preexisting collaterals. Given the need for a way to open occluded subclavian veins and the lack of available alternatives and apparent safety, blunt microdissection may become a routinely applied technique to open occluded subclavian veins.