Presentation
Worsening chest pain over several weeks.
Patient Data
Ascending aortic aneurysm, measuring 5.6 cm anteroposterior, with acute type A aortic dissection. Dissection flap extends from from the aortic valve leaflets to the infrarenal abdominal aorta, with note that the caudal extent is not fully imaged.
Right coronary artery arises from the false lumen. Dissection extends into the origin of the left main coronary artery, with patent flow from the true lumen. Small focal rupture/pseudoaneurysm of the false lumen in the anteromedial wall of the ascending aorta resulting in moderate mediastinal hematoma (see annotated images). It is unclear if this is related to a site of aortic cannulation given the median sternotomy. Small amount of intramural hematoma along the medial ascending aorta on the noncontrast images. No pericardial effusion/hemopericardium is present. Dissection flap extends slightly into origin of brachiocephalic artery.
Majority of the left kidney is nonehancing/infarcted due to extension of the dissection flap into the left renal artery. The right renal artery arises from the true lumen. The SMA arises from the celiac artery, both supplied by the true lumen. IMA also is supplied by the true lumen. The dissection flap extends inferiorly into the lower abdomen and pelvis, which are not completely imaged.
IMPRESSION:
1. Ascending aortic aneurysm, type A dissection, and focal rupture of the false lumen, resulting in moderate mediastinal hematoma. The dissection extends to the origin of the coronary arteries, with the right coronary artery supplied by the false lumen and the left main coronary artery supplied by the true lumen. No hemopericardium.
2. The dissection flap extends through the entire visualized aorta (ascending, arch, and descending) into the lower abdomen beyond the field-of-view. The dissection flap occludes the left renal artery, with infarction of the majority of the left kidney.
3. The right renal artery, combined origin of the celiac artery/SMA, and IMA arise from the true lumen.
Five annotated images demonstrating key findings in the radiology report, indicated by yellow arrows and accompanying text boxes.
Case Discussion
Late presentation of ruptured type A aortic dissection preceded by several weeks of symptoms.
Why did the false lumen rupture, and not the true lumen?
Dissection occurs when blood enters and splits the media through an intimal tear, separating the intima and adventitia. The false lumen has a pressure equal to or greater than the true lumen, reduced elastic recoil compared to baseline, and dilates as a result. This collapses the true lumen, as the dissection flap does not respond to absolute aortic pressures. The wall tension due to aortic pressures is instead completely transferred to the weakened outer wall of the false lumen, which can become so great that it ruptures, as in this case.
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