Type III Endoleaks Following Endovascular Aortic Repair: Three Case Reports

Type III endoleaks, from disconnection between modular stent-graft components (type IIIa) or fabric defects within a limb (type IIIb), are uncommon but potentially life-threatening, transmitting systemic pressure into the aneurysm sac and carrying a high rupture risk. We describe three men with late type III endoleak failure after complex thoracic aortic repair. One presented with rupture at a mid-thoracic modular overlap, salvaged by emergency relining via a hostile femoral cut-down. A second, under surveillance for an asymptomatic endoleak managed conservatively given a static sac, later ruptured at a separate site and died despite emergency relining. A third developed a type IIIb fabric failure in a highly angulated aortic arch, salvaged using a conformable stent-graft and left-ventricular through-and-through wire support. These cases show type III endoleaks may be radiologically subtle yet rapidly fatal, sac stability alone should not determine management, and complex arch morphology demands tailored device selection and access planning.