CV lecture notes Flashcards
risk factors for atherosclerosis?
age, smoking, high serum cholesterol, obesity, diabetes, hypertension, family history
why is obesity a risk factor for atherosclerosis?
fat holds onto inflammatory cells
why is diabetes a risk factor for atherosclerosis?
hypo/hyperglycaemia affects endothelium function
What is the main danger of atherosclerotic plaques?
Can rupture, leading to thrombus formation.
Can occlude, leading to ischaemia/infarction
Distribution of atherosclerotic plaques?
What are haemodynamic factors that affect plaque distribution?
Focal distribution along artery length.
Peripheral and coronary arteries.
Changes in flow such as bifurcations lead to wall thickness changes - neointima
Components of atherosclerotic plaques?
Complex lesion of:
- lipid
- necrotic core
- connective tissue
- fibrous cap of smooth muscle
what is the significance of the fibrous capsule that covers an atherosclerotic plaque?
The thicker it is, the less likely the plaque is to rupture.
how does the ‘response to injury’ hypothesis explain plaque formation?
injury to endothelial cell walls leads to endothelial dysfunction.
This signals to circulating leukocytes which accumulate and migrate to endothelial wall.
Inflammation ensues.
how is adhesion of leukocytes in plaque formation mediated?
chemoattractants on endothelial cell surface send signals to leukocytes. Selectins mediate slow rolling and capture of leukocytes.
Integrins and chemoattractants located in the tissue mediate firm adhesion and transmigration - entice leukocytes in.
what are the 5 stages in the progression of atherosclerosis?
- Fatty streaks: present from about 10yr of age
- Intermediate lesions: foam cells, smooth muscle cells, t-lymphocytes…
- Fibrous plaques/advances lesions: foam cells, smooth muscle cells, t-lymphocytes, macrophages, covered by dense fibrous cap of collagen and elastin.
- Plaque rupture: fibrous cap resorbed and redeposited. Balance shifts in favour of inflammatory conditions, weakening cap and plaque ruptures. BM collagen and necrotic tissue is exposed, haemorrhage of vessels.
- Plaque erosion: collagen triggers thrombosis, small early lesions
what are ‘foam cells’ present in plaques?
lipid laden macrophages
From what stage in atherosclerosis do plaques impede blood flow and are prone to rupture?
what do plaques consist of at this point?
Stage 3: fibrous plaques/advanced lesions
Consist of foam cells, smooth muscle cells, t-lymphocytes, macrophages, covered by dense fibrous cap of collagen and elastin.
what is meant by syncope?
episodes of loss of consciousness
what are the 3 pacemakers of the heart, and how many bpm do they fire at?
SAN - main pacemaker of the heart: 60-100bpm
AVN: back up, 40-60bpm
Ventricular cells: back-up, 20-45bpm
WHat will an electrical impulse that travels towards the electrode show up as on an ecg?
upright, positive deflection
What is the route of conduction of the impulse once generated in the SAN ?
To AVN (slows down impulse, allowing atrial contraction). Then to bundle of his --> bundle branches on either side --> purkinje fibres
PQRST in ECG
What do the letters represent?
P = atrial depolarisation QRS = ventricular depolarisation T = ventricular repolarisation
What are the 12 ECG leads?
12 leads
3 standard limb
3 augmented limb leads
6 precordial leads (v1-v5)
what constitutes a complicated plaque?
calcification, mural thrombus, ulcerated, occluding, vulnerable (thin fibrous cap)
what does ‘immunogenic’ mean in context of an atherosclerotic plaque?
Incited inflammatory response, which may contribute to its growth.
what are the patterns that myocardiac infarction can take and associated ecg trace?
subendocardial - (NSTEMI) partial infarction of muscle wall, ST depression
transmural infarction - (STEMI) total infarction of muscle wall, ST elevation
Progression of acute coronary syndrome will go from unstable angina -> NSTEMI -> STEMI
what are methods for reperfusion of ischaemic myocardium?
- coronary artery bypass grafts
- stenting (PCI) * method of choice*
- Percutaneous transluminal coronary angioplasty (PTCA) balloon tipped catheter, balloon inflated and deflated
thrombolytic enzymes
what is a cardiac aneurysm?
dilation of myocardial wall
how can lung disease lead to heart failure?
Pulmonary hypertension leads to RV hypertrophy and dilatation
what is infective endocarditis?
why does it have high mortality?
infection of the endocardium (inner lining of heart chambers and heart valves), leads to valve distortion and disruption and infected thromboemboli.
30-40% mortality. Hard to spot and treat. Symptoms are generalised and non-specific, such as fever, anorexia, anaemia.
what is myocarditis?
inflammation of the myocardium. Usually viral causes, lymphocytic following upper respiratory tract infection.
3 types of cardiomyopathy (disease of the heart muscle where it becomes enlarged/thick/rigid)
- Dilated cardiomyopathy (DCM). Big, dilated heart, non-specific. Secondary dilated cardiomyopathy can be caused by alcohol/cocaine/pregnancy.
- Hypertrophic cardiomyopathy. Compensatory asymmetrical hypertrophy in response to dysfunction. Accounts for 5-10% sudden deaths in young adults.
- Arrythmogenic - dilated RV, fat, tissue, inflammatory cells
What is the commonest vascular disease and how may it present?
Giant cell arteritis.
Focal, chronic and granulatomous inflammation of temporal arteries which may affect the opthalmic arteries leading to sudden blindness.
Headaches, joint pain, facial pain, fever, and difficulties with vision, and sometimes permanent visual loss in one or both eyes.
Common examples of vascular disease?
Hypertensive vascular disease: usually idiopathic, 20-30% population >140/90mmHg
Giant cell arteritis
Abdominal aortic aneurysm
Berry aneurysm (commonly in branching points of circle of Willis)
Varicose veins
When is an abdominal aortic aneurysm considered at risk of rupture and operated on?
When it reaches >5-6cm diameter
what is angina?
a symptom which occurs as a result of restricted coronary blood flow, almost exclusively secondary to atherosclerosis
WHY does angina occur?
Mismatch between oxygen demand and oxygen supply to the heart:
- impairment of blood flow by proximal arterial stenosis affects supply
- increased distal resistance (eg LV hypertrophy) increasing demand
- reduced oxygen carrying capacity in the blood eg in anaemia
on ECG paper, horizontally what does one small box represent? What about one large box?
One small box = 0.04s/40ms
• One large box = 0.20s
on ECG paper, vertically what does one large box represent?
• One large box = 0.5mV