A Prospective, Multicenter, Non-Blinded, Non-Randomized Study of the RelayPro Thoracic Stent-Graft in Subjects With an Acute, Complicated Type B Aortic Dissection

• Subject must have an acute (symptom onset to diagnosis within 2 weeks)or subacute, complicated type B aortic dissection (entire dissection is distal to the left subclavian artery (LSA)), confirmed by Computed Tomography Angiography (CTA) or Magnetic Resonance Angiogram (MRA), with time from symptom onset to diagnosis ≤ 6 weeks, with at least one of the following:

• Malperfusion of the viscera, kidneys, spinal cord, or lower extremities, measured by clinical or radiographic evidence;

• Rupture;

• Intractable pain.

• Proximal and distal aortic neck with diameter between 19 mm and 42 mm.

• Subject's anatomy must meet all of the following anatomical criteria:

• Proximal attachment zone distal to the left common carotid and a distal attachment zone proximal to the origin of the celiac artery. (Dissection is permitted in the distal attachment zone but is not permitted in the proximal attachment zone.)

• The length of the attachment zones will depend on the intended stent-graft diameter and type of graft selected.

• The proximal attachment zone should be 15 mm for 22 - 28 mm RelayPro grafts with bare stent (20 mm for RelayPro grafts with non-bare stent), 20 mm for 30 - 46 mm RelayPro grafts with bare stent (25 mm for RelayPro grafts with non-bare stent), and proximal to non-dissected segment (healthy zone).

• The distal attachment zone should be 20 mm for all RelayPro grafts.

• Coverage of the left subclavian artery is permitted with mandatory revascularization if patent left internal mammary artery (LIMA) bypass or left upper extremity (LUE) arteriovenous graft or anomalous vertebral artery off the aorta. Revascularization must be performed prior to device placement, and may occur during implant procedure, provided it is before coverage of the LSA by the endograft.

• Proximal attachment zone containing a straight segment (non-tapered, non-reverse-tapered, defined by <10% diameter change) with lengths equal to or greater than the required attachment length for the intended device.

• Vascular dimensions (e.g., aortic diameters, length from left subclavian to celiac artery) must be in the range that can be safely treated with the RelayPro Thoracic Stent-Grafts.

• Adequate iliac or femoral artery access for introduction of the RelayPro Delivery System. Alternative methods to gain proper access may be utilized (e.g., iliac conduit).

• Subject willing to comply with the follow-up evaluation schedule.

• Subject (or Legally Authorized Representative, LAR) agrees to sign an Informed Consent Form prior to treatment.