This device uses a 21 Fr cannula percutaneously inserted into the femoral vein for transseptal access of the left atrium with a 15 Fr catheter placed in the contralateral femoral artery and positioned above the aortic bifurcation. An extracorporeal pump then returns oxygenated blood from the left atrium to the arterial system, thereby unloading the left ventricle.550,551 The hemodynamic effects have been studied in patients undergoing high-risk PCI.552 Several small studies have addressed the clinical efficacy of the TandemHeart in high- risk patients undergoing PCI.551,553 556 In a single-center report of 68 patients undergoing high-risk PCI using either TandemHeart or Impella Recover 2.5, success rates ( 90%) and vascular complications (7%) were similar.553 High-risk patients may include those undergoing unpro- tected left main or last-remaining-conduit PCI, those with severely depressed EF undergoing PCI of a vessel supplying a large territory, and/or those with cardiogenic shock. Patient risk, hemodynamic support, ease of application/removal, and operator and laboratory expertise are all factors involved in consideration of use of these devices. With devices that require large cannula insertion, the risk of vascular injury and related complications are important considerations regarding necessity and choice of device. 5.7. Interventional Pharmacotherapy 5.7.1. Procedural Sedation The term conscious sedation is falling out of favor with the recognition that there is a spectrum of procedural sedation levels. Most patients undergoing PCI fall under the definition of either minimal sedation (anxiolysis) or moderate sedation (depressed consciousness with the ability to respond purpose- fully to verbal commands).557 Nonetheless, an underlying principle of procedural sedation is that the physician should be prepared to manage one level of sedation deeper than the level intended. 