Vascular & Ischaemic Heart Disease Flashcards
What is the difference between a thrombus and embolus?
A thrombus is a solid mass of blood components that forms locally in a vessel, while an embolus is a particle that moves about in our blood vessels, either in the veins or arteries.
What are fatty streaks and what causes them?
Lipids within macrophages causes by endothelial damage
What are the stages of atherosclerosis?
1) Endothelial damage stimulates the accumulation and oxidation of LDL-C in the vessel wall. 2) Monocytes migrate from the blood into the subendothelial intima and transform into macrophages, which accumulate lipids to form foam cells which appear as fatty streaks. 3) Production of inflammatory mediators stimulate deposition of elastin and collagen, leading to formation of the fibrous cap - fibrofatty plaque. 4) This causes the vessels to lose elasticity and leads to a cycle of more endothelial damage > streaks > fibrosis 4) Eventually the fibrous cap may weaken and rupture, exposing the underlying thrombogenic tissues. 5) This can induce further thrombus formation resulting in continued luminal narrowing or even arterial occlusion
Atheroma
An atheroma is an accumulation of degenerative material in the tunica intima of artery walls
Where do atheroma tend to form first and worst?
At areas of turbulent flow such as where vessels branch
What are the complications of atheroma?
1) Arterial stenosis (narrowing of the lumen) 2) Ischaemia 3) Thrombosis with infarct 4) Aneurysm (due to weakening of wall) 5) Arterial dissection 6) Embolism
Which arteries does arterial stenosis from atherosclerosis commonly occur?
Coronary, carotid, renal and peripheral arteries (eg. claudication)
Thrombosis
Formation of a solid or semi-solid mass from the constituents of blood, within the vascular system, during life.
How does an embolism form from atherosclerosis?
Piece of the plaque or thrombus breaks off and moves along the circulation until it reaches a smaller vessel and lodges
Ischaemia
Result of impaired vascular perfusion depriving the affected tissue of nutrients (inc. O2).
Infarction
Ischaemic necrosis of a tissue or organ secondary to occlusion/reduction of the arterial supply or venous drainage.
What is Virchow’s Triad of factors which contributes to thrombosis?
- Changes in vessel walls (endothelial injury) 2. Changes in blood constituents (hypercoagulability) 3. Changes in blood flow (stasis)
What is the role of platelets?
Close small breaches in vessel walls by temporary patching with collagen when in contact with sub-endothelial layers. If activated in a vessel = thrombus
What is the role of the endothelial cell?
- Maintains a permeability barrier - Manages anticoagulant, antithrombotic, fibrinolytic regulators (Keeps the blood in a fluid state) - Manages prothrombotic molecules (When damaged, allows the blood to clot) - Produces EC Matrix - Modulates blood flow and vascular reactivity via vasoconstrictors - ACE and vasodilators – NO - Regulates inflammation and immunity - Regulates cell growth - Role in LDL oxidation
What 2 groups can conditions causing hyper coagulability be split into?
Acquired e.g. MI, prosthetic valves, AF and genetic e.g. factor V mutations
What are the main underlying causes of thrombosis in arteries and veins?
In arteries: atheroma In veins: stasis
Embolism
Any detached intravascular solid, liquid or gaseous mass which is carried by the bloodstream to a site distant from the point of origin.
What types of embolism re there?
- Thromboembolism - Fat embolism - Marrow embolism - Air embolism - Septic embolism - Amniotic fluid embolism - Tumour embolism
Pulmonary thromboembolism
Emboli where 95% of which derive from large leg veins (popliteal, femoral, iliac) and travel via IVC to pulmonary circulation
True or False: Venous emboli cause infarcts in peripheral arterial circulation
False, DVTs etc only cause infants in the venous circulation or pulmonary circulation. Except if if there is an atrial/ventricular septal defect
What usually predisposes pts to fat emboli?
Generally follows soft tissue trauma or major bone fractures
What usually predisposes pts to gas/air emboli?
Barotrauma eg. in divers or others such as delivery/abortion
What occurs in amniotic fluid embolism?
Amniotic fluid and debris enters torn veins and embolises to lungs
What 3 disease patterns does arteriosclerosis cover?
1) Atherosclerosis 2) Arteriolosclerosis 3) Monckeberg Medial Calcific Sclerosis
Angina
Visceral pain from myocardial hypoxia
What are the characteristic patterns of angina?
• Provocation – exercise, cold day • Relief – within a few seconds – minute after stopping/resting or GTN spray • Timing – generally lasts less than a few hours
What investigations can be done for angina?
- Exercise testing - Perfusion imaging - CT angiography
Which drugs can be used in the management of aspirin?
- Aspirin: Antiplatelet - ß blockers: Slow heart rate, reduce O2 demand - Statin: Reduces cholesterol - ACE inhibitor: Reduces blood pressure
What are the general indications for PCI vs revascularisation (CABG)?
PCI - acute coronary syndrome Revascularisaton - chronic stable angina
Peripheral vascular disease
Circulation disorders affecting the vasculature outside the heart and brain, most often caused by atherosclerosis. Can affect either the arteries of veins
Peripheral arterial disease
Vascular disease specifically occurring in the arteries
Chronic lower limb ischaemia
Form of peripheral arterial disease. The gradual loss of blood supply to the lower limbs,
Intermittent claudication
Symptom of peripheral vascular disease - ‘angina of the legs’. - Mostly occurs due to atherosclerosis thus limiting the blood supply particularly when demand increases
Which system is used to classify the severity of PAD symptoms?
Fontaine classification