A case report of Impella 5.5-induced accordion phenomenon of the right subclavian artery during coronary bypass surgery.

Background: The Impella 5.5 has recently been introduced as a high-flow mechanical circulatory support device and is increasingly used to stabilize high-risk patients undergoing coronary artery bypass grafting (CABG). Although its peri-operative benefits have been described, reports on vascular complications remain limited. Case summary: A 73-year-old man on maintenance haemodialysis with progressive left ventricular dysfunction was scheduled for CABG under Impella 5.5 support. Pre-operative computed tomography (CT) showed a minimum luminal diameter of 7 mm in the right axillary artery, and the device was inserted through a prosthetic graft the day before surgery. Immediately after device placement, right radial pulsatility markedly decreased. Angiography revealed faint distal flow and an accordion-like deformation of the right subclavian artery. Because significant vascular injury was considered unlikely and the hand remained well perfused, CABG was performed without vascular reconstruction. After successful CABG, the Impella was removed on post-operative Day 1, resulting in immediate restoration of right radial pressure. Post-operative CT confirmed the absence of vascular injury, and the patient recovered without any neurological or ischaemic sequelae. Discussion: This case represents a rare instance of transient upper limb hypoperfusion caused by an accordion phenomenon of the subclavian artery during Impella 5.5 support. The phenomenon mimicked structural injury but resolved completely after device removal. The case underscores the importance of detailed pre-procedural vascular imaging, continuous limb perfusion monitoring, and awareness of reversible pseudo-lesions induced by Impella catheter-related straightening of tortuous vessels.