Week Five - Case Two Flashcards
what sort of pain is associated with aortic dissection
central pain radiating to the back. not affected by exertion, movement or position and is not pleuritic
what the CXR findings for aortic dissection
mediastinal widening
widened aortic knob
trachea can be deviated also
what are significant consequences of aortic dissection
MI and pericardial effusion with tamponade
when can you only assess cardiomegaly on CXR
on a PA film
what are the most common signs of aortic dissection
pulsus paradoxus
pulse deficits
distended neck veins
muffled heart sounds
what is the definition of pulse deficits
a difference of 20mmHg or more in blood pressure between left and right arms
what are the risk factors for aortic dissection
hypertension which is poorly controlled (70% of patients)
atherosclerosis (30%)
aortopathy such as bicuspid aortic valve disease (16%)
connective tissue disorders such as Marfan’s (5%)
what should be arranged if an aortic dissection is suspected
an urgent contract thoracic aortogram should be arranged
what is the mortality risk associated with aortic dissection
untreated it is very high - 50% within the first 48 hours.
what is Type A aortic dissection
aortic dissection involving the ascending aorta
what classification is used for aortic dissection
Stanford Classification
what is Type B aortic dissection
aortic dissection not involving the ascending aorta
what should be sought for a Type A
urgent cardiothoaric surgical advice should be sought for immediate surgery
what should be sought for Type B
urgent vascular surgical referral should be made and patient should be admitted for BP control and monitoring in a cardiac care of high dependency unit
what is recommended to reduce the risk
lifestyle modification is recommended to reduce the risk and includes smoking cessation
what are the 5 steps in the pathophysiology of aortic dissection
- patients usually have an underlying aortic pathology, predisposing to dissection
- an intimal tear of the lining of the aortic causes sudden onset chest pain. this is called an aortic dissection
- subsequently there is movement of blood through the tear between the intima and medial layers of the aorta. this gives rise to a true and false lumen
- the false lumen enlarges and can occlude the true lumen potentially compromising the blood supply of organs distal to the original dissection tear. the original dissection can also extend. these can give rise to ongoing chest pain
- type A dissection is a cardiothoracic surgical emergency. type B is a vascular surgery emergency
what is the link between Marfan’s and aortic dissection
Aortic dissection / dilatiation – particularly at the aortic root. The arotic media is less resistant to stretching, particularly in areas of high pressure – hence the involvement of the aortic root. In severe cases, dissection can occur before the age of 10! Aortic regurg and endocarditis are also common
what are the three layers of the aortic wall
intima, media, and adventitia
what happens when there is constant exposure to high pulsatile pressure and shear stress
leads to a weakening of the aortic wall in susceptible patents resulting in an intimal tear
following this, blood flows into the intimal-media space, creating a false lumen
where do most of the tears take place and why
most take place in the ascending aorta, usually in the right lateral wall where the greatest shear force on the aorta occurs
what can ADD propagate
anterograde and/or retrograde and depending on the direction the dissection travels, cause branch obstruction that produces ischemia of affected territory
what can proximal type A AADs instigate
acute tamponade, aortic regurgitation or aortic rupture
what are both the true and false lumen lined with
in an ADD, the true lumen is lined by the intima whereas the false lumen is within the media
in most cases, the true lumen is smaller than the false lumen
what are the three common sites for ADD
nearly 2-2.5cm above the aortic root
just distal to the origin of the left subclavian artery
in the aortic arch
