An aortic dissection is a serious condition in which a tear occurs in the inner layer of the aorta. Blood flows through the tear and into the wall of the aorta. This forces the inner and middle layers of the aorta to split apart (dissect), creating 2 passages (a true lumen and a false lumen). As more blood flows into the new false lumen the dissection extends along the aorta. This can lead to aortic rupture or decreased blood flow (ischaemia or malperfusion) to organs.
Aortic dissections are classified into 2 types, depending on which part of the aorta is affected. Type A dissection involves a tear in the ascending part of the aorta. The tear may also occur in the aortic arch, which may extend into the abdomen or back into the ascending aorta. Type B dissection involves a tear in the aorta beyond the arch, usually in the descending thoracic aorta. Dissections can be acute or chronic.
Treatments for aortic dissection include medicines (to control hypertension) and surgery (to repair the aorta, and possible replacement of the aortic valve). Type of treatment depends on the chronicity, site location, and whether there are complicating features. Acute type A aortic dissection is life threatening and needs immediate surgery. The goals of surgical repair are to seal the false lumen and resolve malperfusion.
Insertion of aortic remodelling hybrid stent is incorporated into open hemiarch repair for an acute type A aortic dissection, under general anaesthesia. The device is a self-expanding bare-metal stent with a short felt sewing cuff end. It aims to resolve malperfusion and promote positive remodelling of the aorta.
During the hemiarch aortic reconstruction, once circulatory arrest is established, the ascending aorta is transected and resected in the standard manner. A hybrid stent is then inserted until the entire device is inside the true lumen. This is usually done under direct vision, although it can be implanted using a guidewire. The cuff end of the stent is placed level with the edge of the transected aorta and attached with interrupted sutures. The uncovered portion of the stent expands along the aortic arch into the descending aorta. The remainder of the surgical hemiarch aortic reconstruction is completed in the usual way.