Case report. The patient is an 82-year-old man with a medical history significant for atherosclerotic heart disease, rheumatoid arthritis, coronary artery bypass surgery, aortic valve replacement, New York Heart Association class III congestive heart failure on optimal drug therapy (captopril, furosemide, carvedilol, metolazone) and a left ventricular ejection fraction of 20%. The patient had a prior permanent pacemaker inserted for complete heart block and had a QRS duration of 160 msec. He had been complaining of increasing dyspnea on exertion for the past 7 months with an acute decompensation over the last month, and increasing lower extremity edema, rapid palpitations and bouts of near syncope. The patient was referred for an electrophysiology study and possible upgrade to a biventricular device. The electrophysiology study identified sustained monomorphic ventricular tachycardia at a cycle length of 210 msec and the patient was referred for biventricular implantable cardioverter-defibrillator upgrade. The old pacemaker was explanted and the pocket revised to accommodate the newer device. During the electrophysiology study, a very unusual right heart anatomy was observed in which we were unable to identify the coronary sinus vein with a steerable 20-pole catheter from the right femoral vein. The right ventricular apex was unable to be identified and only a narrow passage which led to the outflow tract was observed due to altered anatomy post-aortic valve replacement. During the biventricular implantable cardioverter-defibrillator implant, a newly marketed steerable introducer (Prevail, Medtronic Inc., Minneapolis, Minnesota) was utilized to help identify the coronary sinus vein. A left subclavian venopuncture was used and the introducer sheath entered the right atrium. In the left anterior oblique position, the catheter was torqued towards the septum and contrast was injected through the sheath in order to visualize the anatomy. By steering the catheter from the most inferior part of the right atrium and injecting small puffs of contrast, the coronary sinus ostium was visualized and a left ventricular pacemaker lead was placed. Due to the unusual right ventricular anatomy with only the right ventricular outflow tract being accessible, a ventricular defibrillator lead was placed in the proximal component of the coronary sinus vein in order to achieve defibrillation. The pace-sense component of the old device was used for right ventricular pacing. The left and right ventricular leads were attached to the biventricular implantable cardioverter-defibrillator. There was no atrial activity (atrial standstill), thus the atrial port was plugged. Discussion. Figure 1 shows the steerable introducer sheath used in this case, with the adjustable steering mechanism which achieves a tighter radius. Figure 2 shows the fluoroscopic images obtained during the implant. Figure 2A shows the introducer sheath inside the coronary sinus with the left ventricular lead being introduced. Figure 2B shows a right anterior oblique projection in which the defibrillator lead was placed in the proximal coronary sinus due to the inability to implant the lead in a position other than the right ventricular outflow tract (adjacent to the right ventricular pacing lead). Figure 3 shows the PA and lateral chest x-rays post-procedure. Note: the patient felt at least one full New York Heart Association classification better 3 days post-procedure. This case illustrates the utility of a novel, steerable introducer sheath to help elucidate the coronary sinus ostium and vein in a case with difficult anatomy. To our knowledge, we are the first institution to utilize this device after the U.S. Food and Drug Administration approval prior to market release. Previously, a number of preformed sheaths and catheters have been utilized to help identify the coronary sinus ostium.1-3 Intracardiac echocardiography has been used to facilitate defining anatomy during electrophysiology studies and catheter-based procedures.4-10 To emphasize the difficulty of some of these procedures, we reported a case of intracardiac ultrasound which helped visualize the coronary sinus ostium to achieve a successful implant.11 In closing, a steerable introducer sheath provides a significant advance over existing technology and may prevent sheath exchange in these cases. Reprinted with permission from the Journal of Invasive Cardiology 2004;16:600-601.