- An aneurysm is dilation of the arterial wall to >1.5 times it normal diameter.
- It can be either true, pseudo or mycotic aneurysm,
True aneurysm :
- The wall of true aneurysm consists of all layers of the vessel wall.
- Larger aneurysm is likely to rupture once the stress on the vessel wall exceeds its tensile strength.
- As the aorta dilates, the force on the aortic wall increases, which causes further aortic dilatation. Laplace law: wall tension x radius.
Pseudoaneurysm
- Consists partly of the vessel wall and partly of fibrous or other surrounding tissue.
- It can develop at the site of previous arterial cathetrisation or at anastomoses from prior vascular reconstruction, or due to trauma or infection.
Mycotic aneurysm
- It develops as a result of infection.
- Common in immunocompromised.
Popliteal artery aneurysm is the commonest peripheral aneurysm.
AORTIC ANEURYSM
Risk factors for aortic aneurysm
- High blood pressure
- Male
- Genetics Inherited conditions that adversely affects the supporting connective tissue.
- Aging: the aorta becomes less elastic and stiffer than age.
- Infections : can damage lining of the heart and aorta.
- Trauma: falls or motor vehicle collision can injure the aorta.
Aortic aneurysm can be either abdominal or thoracic aneurysm
Abdominal aneurysm
- Abdominal aortic aneurysm is defined as an aneurysm > 3.0cm in diameter and repair is considered for an aneurysm >5.0 cm in diameter.
Clinical Feature
- They present commonly with back pain or abdominal pain. It is often severe and abrupt in onset. It is usually described as a tearing pain.
- Syncope suggests rupture of aneurysm with cerebral hypoperfusion.
- GI bleeding from aortoduodenal fistula,
- Extermity ischemia from embolisation of a thrombus in the aneurysm.
- Pulsatile abdominal mass
- Tenderness on palpation may be a sign of aneurysmal expansion or rupture.
- Signs of aortic rupture include turners sign, cullens sign, scrotal or vulval hematoma or inguinal masses.
Differential Diagnosis
- Pancreatitis
- Hepatobiliary disorders
- Renal disorders
- Other differential diagnosis for syncope and chest pain.
Diagnosis
- Emergency bedside USG
- >90% sensitivity
- Aneurysm is measured from the outsside margin of one wall to outside margin of the opposite wall in both transverse and longitudinal planes.
- CT with IV contrast
Management
- Airway, Breathing
- Circulation
- Secure two large bore IV cannulas
- Cardiac monitoring
- Permissive Hypotension & bradycardia
- Here the aim is to reduce the mean arterial pressure and aortic shear force.
- Target mean arterial pressure is between 60 -70 mmHg
- It is achieved by using sedatives, analgesics, vasodilators, beta blockers like esmolol.
- Definitive treatment
- Open AAA repair using a prosthetic graft.
- Endovascular stent graft
Update on 27/4/13
Reference
- Tintinalli
- Vascularsurgery.org