Type A Aortic Dissection Repair

In an acute aortic dissection a tear in the inner lining of the aorta lets blood force its way into the middle layer and split the wall lengthwise, creating a false channel (false lumen) beside the true one. A Stanford type A dissection involves the ascending aorta. It is a surgical emergency: the dissection can run back into the root and make the aortic valve leak, block a coronary artery, or burst into the pericardium and cause tamponade, and it can cut off blood to the brain, gut, kidneys or legs. These patients often come straight to the OR, so the room must be set up quickly and blood products, a cell saver and the full aortic setup must be ready. What makes this operation different from an elective aneurysm repair is the fragile, layered aortic wall and the false lumen. The arterial cannula must deliver blood into the true lumen, so it is placed in an artery that is not dissected (often the right axillary artery through a side graft, sometimes the femoral artery, the true lumen of the aorta over a guidewire under TEE, or through the left ventricular apex). Clamping the dissected aorta can injure it, so most of the repair is done under hypothermic circulatory arrest. The torn segment is removed, the separated layers at each cut end are rejoined with surgical glue and Teflon felt strips, the valve's commissures are resuspended so the valve stops leaking, and a tube graft is sewn in, its far end under the arch (hemiarch) and its near end just above the valve. When bypass restarts it must flow forward through the graft, never only backward from the groin, which could push blood into the false lumen. If the root or valve is destroyed, a root replacement (Bentall or valve-sparing) is added, and if the tear extends into the arch a hemiarch or total arch replacement is done. Bleeding is the main early problem after deep hypothermia, so expect hemostatic agents, glue, felt and many units of blood products.