Pathophysiological Consequences of AAD
The pathophysiological consequences of AAD include:
Rupture into various body cavities
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Rupture into various body cavities |
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|---|---|
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Ascending aorta |
Haemopericardium (syncope and/or sudden death) Right haemothorax (invariably sudden death) |
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Arch of aorta |
Mediastinal haematoma Interatrial septal haematoma (cardiac conduction defects) Compression of pulmonary trunk/artery |
|
Descending aorta |
Left haemothorax (sudden death) Rarely into oesophagus (profuse haematemesis) |
|
Abdominal aorta |
Retroperitoneal haemorrhage (back pain with shock) Rarely intraperitoneal haemorrhage (shock and acute abdomen) |
AAD can result in rupture of the dissection into various body cavities.
A haemopericardium which resulted from a tear in the ascending aorta is shown in the image below.
Click on the image to enlarge.
Occlusion of any of the branch vessels of the aorta with consequent distal organ ischaemia
| Coronary vessel(s) | ST elevation myocardial infarction |
| Common carotid(s) | Any type of stroke |
| Subclavian(s) | An acutely ischaemic upper limb |
|
Coeliac/ mesenteric vessel(s) |
Ischaemic bowel |
| Renal vessel(s) | Frank haematuria |
| Spinal artery(ies) | Sudden onset painless paraplegia |
Pulse deficits are a classic feature of AAD and represent occlusion of branch vessels of the aorta. There are two ways this can happen:
- Smaller branches may be simply compressed at the point of origin without the dissection progressing within the tunica media
- The dissection progresses within the media of the branch vessel and the false lumen becomes so large it compresses the true lumen of the vessel
Occasionally, an obstructed branch vessel can have its blood flow restored either because of a re-entry tear into the true lumen or because an intimal flap only intermittently obstructs the origin of the vessel as the flap extends or moves with aortic blood flow.
A dissection of a coronary artery with compression of the true lumen by the larger false lumen can be seen in the image below.
Click on the image to enlarge.
Acute or progressive aortic regurgitation
This occurs when the dissection process extends into or around the aortic valvular support. When this happens the aortic root can dilate so much that the aortic leaflets cannot fully appose during diastole thereby allowing regurgitation of blood through the cusps. The resultant murmur may be of any grade of intensity and may be inaudible if there is associated haemopericardium.
Patients who survive the dissection process may have a delayed presentation with cardiac failure.