Aortic dissection occurs due to shearing stress from pulsatile pressure causing a tear in the tunica intima of the aortic wall. This tear allows blood to flow into the media, creating a “false lumen.” Aortic dissection is most commonly caused by uncontrolled hypertension. Complications arise due to partial occlusion of vital branches off the aorta and reduced blood flow to the brain, visceral organs, and extremities. Patients often present with acute, tearing chest or back pain. Computed tomography is the diagnostic modality of choice. All type A dissections (ascending aorta) are a surgical emergency due to the risk of imminent rupture. Type B dissections (descending aorta) can be managed medically with impulse control using beta-blockers and calcium channel blockers. If there is evidence of malperfusion to visceral organs or extremities, aneurysm dilation to > 5 cm, retrograde extension into the ascending aorta, or intractable pain, the patient will need evaluation for endovascular or open repair.
Last updated: 10 Feb, 2021
False versus true lumen in aortic dissection
The reconstructed computed tomography (CT) image of an aortic dissection:
1
axial
Axial
Computed Tomography (CT) slice of the CT scan (a); reconstructed surface of the aortic dissection (b); positions of the entries along the intimal flap (c; indicated by arrows).
Illustration of an aortic dissection
A tear in the intima allows blood to
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure into the media.
Mechanisms of aortic dissections
A tear in the intima, rupture of the
vasa vasorum
Vasa vasorum
Nutrient blood vessels which supply the walls of large arteries or veins.
Arteries: Histology, and
ulceration
Ulceration
Corneal Abrasions, Erosion, and Ulcers of an
atherosclerotic plaque
Atherosclerotic plaque
Lesions formed within the walls of arteries.
Atherosclerosis
TL: true lumen
FL: false lumen
Computed tomography findings in aortic dissection
A: CT scan showing an ascending aortic dissection (gray arrow)
B: CT scan demonstrating an
aortic arch
Aortic arch
Mediastinum and Great Vessels: Anatomy dissection (gray arrow)
Computed tomography findings in aortic dissection
CT scan demonstrating the dissection at the level of the
aortic valve
Aortic valve
The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle.
Heart: Anatomy
Computed tomography findings in aortic dissection
Aortic dissection extending into the left subclavian and axillary
arteries
Arteries
Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles.
Arteries: Histology, and to the level of bifurcation of the common iliac artery (thick arrows)
Magnetic resonance imaging demonstrating a descending thoracic aortic dissection:
A:
sagittal
Sagittal
Computed Tomography (CT)
gadolinium
Gadolinium
An element of the rare earth family of metals. It has the atomic symbol gd, atomic number 64, and atomic weight 157. 25. Its oxide is used in the control rods of some nuclear reactors.
Magnetic Resonance Imaging (MRI)-contrast-enhanced
MRA
MRA
Imaging of the Heart and Great Vessels view
B:
axial
Axial
Computed Tomography (CT) black blood view of the proximal descending thoracic
aorta
Aorta
The main trunk of the systemic arteries.
Mediastinum and Great Vessels: Anatomy
C:
axial
Axial
Computed Tomography (CT) true FISP (
steady state
Steady state
Enzyme Kinetics-free precession) cine view
D:
axial
Axial
Computed Tomography (CT) phase-contrast view, showing
flow
Flow
Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.
Vascular Resistance, Flow, and Mean Arterial Pressure patterns in the true and false lumens of the
descending aorta
Descending aorta
Mediastinum and Great Vessels: Anatomy (the true lumen is indicated by the white arrow)
Type A dissections require emergent surgical intervention for replacement of the involved ascending aorta Ascending aorta Mediastinum and Great Vessels: Anatomy or the entire ascending aorta Ascending aorta Mediastinum and Great Vessels: Anatomy with Dacron graft Graft A piece of living tissue that is surgically transplanted Organ Transplantation.