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Type A Dissection

Acute ascending aortic dissection (type A) is a true surgical emergency. Arterial walls are comprised of the intima (innermost layer), media, and adventitia (outermost layer). In a dissection, an intimal tear creates a plane between the intima and media and a “false lumen” that can compromise blood flow to branches off the aorta (carotids, coronaries, visceral organs, etc.) Dissections can also rupture leading to massive hemopericardium or internal bleeding resulting in death. In fact, if untreated, the mortality rate is 1-2% PER HOUR, so operative intervention is warranted ASAP!

As a cardiothoracic anesthesiologist, it’s my job to maintain impulse control to minimize sheer forces that could worsen (or rupture) the dissection until my surgical colleagues can get the patient on cardiopulmonary bypass. Coagulopathy is also expected especially given that many of these patients end up receiving deep hypothermic circulatory arrest – a portion of the surgery where the patient is cooled to half the normal body temperature for global organ protection while all circulation is stopped to resect and replace the diseased aorta. Furthermore, intraoperative transesophageal echocardiography (TEE) allows me to determine if the aortic valve (which can often be compromised by the dissection) needs to be replaced/repaired, if there is potential coronary artery involvement, etc.

This image shows a dilated, inflamed ascending aorta with a large dissection flap proximally towards the aortic annulus and distally to the proximal descending thoracic aorta (not shown).

Drop me a comment with your experiences regarding type A dissections!

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