Cardiovascular pathology Flashcards
What is an aneurysm
Abnormal dilatation in an artery due to weakness on the vessel wall
What are the risk factors for AAA
*HTN
*Atherosclerosis
*Male, smoking, age >60, FHX, connective tissue disease, vasculitis, diabetes, trauma, congenital abnormalities of the aorta, infection, inflammation
Most common causes of AAA
Atherosclerosis, congential disease, mycotic, immunological, syphillis, trauma, salmonella
Morphological features of an AAA
*Localised dilatation of the abdominal aorta
*Usually between the renal arteries and bifurcation of the aorta into iliac arteries
Aneurysm often contains atheromatous ulcers covered with mural thrombi, with associated thinning and destruction of the media
Describe the pathogenesis of an aneurysm
*Occur when the structure or function of the connective tissue within the vascular wall is compromised
*Atherosclerotic plaque in the intima, compresses the media which cause degradation.
*This leads to cystic medial degeneration
*There is local inflammation, protelytic enzymes degrade the collagen, there is involvement of matrix metalloproteinases
*This results in loss of vascular smooth muscle cells, and inappropriate synthesis of non-elastic extracellular matrix
What are the clinical consequences of an aneurysm
*Painless mass
*Rupture- increased when diameter is >5cm. Can be retroperitoneal or intraperitoneal
*Obstruction-of branches such as mesenteric, vertebral or renal arteries
*Embolism of plaque or thrombus
*Impingement of plaque or compression of adjacent structures
*Infection or mycotic aneurysm
Risk of rupture of an AAA?
*<4m negligible
*4-5cm 1% per year
*5-6cm 11% per year
*>6cm 35% per year
What are thee risk factors for aortic dissection
*Male
*Age 40-60
*Hypertension
*Connective tissue disorder
*Iatrogenic- complication of arterial cannulation or coronary artery bypass
*Trauma
Describe the pathogenesis of an aortic dissection
*Hypertension with media hypertrophy as vasa vasorum and degeneration of the media
*and/or connective tissue disease (inherited or acquired)
*These cause weakness in the media
*Dissection begins with an intimal tear and the blood dissects into a tear in the media either distally or proximally within the media
How are dissections classifed?
- Stanford. Type A is proximal, type B distal
*Debakey
—>Type 1- ascending and descending
—>Type 2- ascending
—> Type 3- Descending only
Potential consequences of aortic dissection>
*Rupture back into the intima or out through the adventitia
*Rupture out or into the pericardial, pleural or peritoneal cavtities
*Cardiac tamponade, aortic insuffieciency via involvement of the aortic valve, MI, distal ischeamia and/ or spinal cord ischeamia via dissection into renal, mesenteric, formal or spinal vessels
*Death
What are the pathological consequence of aortic stenosis
*Concentric left ventricular hypertrophy
*LV outflow obstruction
*Angina/ myocardial ischeamia in the abscence of CAD
*Syncope
*Aortic dissection
*Heart failure
*Endocarditis (uncommon)
What are the causes of aortic stenosis
*Calcified/ degenerative
*Bicuspid
*Rheumatic heart disease
What clinical signs may differentiate calcific aortic stenosis from rheumatic aortic stenosis
*Rheumatic disease typically involves more than one valve
*Abscence of MS/MR and the abscence of Aortic regurgitation are more suggestive of calcific aortic stenosis
What are the predisposing factors for calcific aortic stenosis
*Age- over 70 for normal valve
*Wear and tear, chronic injury to the valve
*Bicuspid valve or other congential abnormality
*Hyperlipidaemia
*Hypertension
*Inflammation
What are the potential complications of congenital bicuspid aortic valve
*Major: calcification and stenosis
*Others: regurgitation, infective endocarditis, aortic dilatation, dissection
What are the systemic factors that lead to atherosclerosis
*Hypertension
*Hyperlipidaemia
*Smoking
*Hyperhomocysteninemia
*Infection
*Inflammation and inflammatory cystokines
What are local factors that lead to atherosclerosis
*Haemodynamic disturbanes i.e. turbulance at branch points
*Endothelial dysfunction
What arteries are most often affected by athersclerosis?
*Lower abdominal aorta
*Coronary arteries
*Popliteal arteries
*Internal carotids
*Vessels of the circle willis
Outline the steps involved in the pathogenesis of atherosclerosis
*Endothelial injury and dysfunction
*LDL accumulation and oxidation in the vessel wall
*Monocyte adhesion and migration into the intima and transformation into foam cells and macrophages
*Platelet adhesion
*Smooth muscle cell migration from media to intima
*Smooth muscle proliferation into the intima
*Enhances lipid accumulation within the intimal cells