cardiovascular diseases 1 Flashcards
what factors reduce blood supply to the myocardium resulting in ischameia
reduced coronary flow
myocardial hypertrophy
vasculitis, amyloid deposition, coronary artery dissection.
pathogenesis if acute and chronic ischameia.
auto-regulation of coronary blood flow which breakdown in occlusion.
low diastolic flow- especially subendocardial.
Active aerobic metabolism of cardiac muscle- reduced
Myocytes dysfunction and eventually will lead to cell death.
what is the time frame for recovery via repercussion of a oxygen starved heart
15-20 mins
4 common ischaemic heart disease syndromes
angina pectoris
acute coronary syndrome
sudden cardiac death
chronic ischaemic heart disease
3 types of angina pectoris
typical/stable- luminal narrowing and manifestation upon stress.
Crescendo/unstable plaque- disrupted so thrombus or emboli form, resulting in pain in an uncontrollable fashion.
Variant/prinmetal- fixed obstruction but effects are not predictable.
what is shown on an ECG in acute coronary syndrome
ST elevation
what are the main factors resulting in acute ischaemia
atheroma and thrombosis. lipid rich plaques. Transmural MI Thrombolysis Myocardial stunning- contractility of the heart is abnormal
how is acute iscahemia diagnosed
ECG, cardiac proteins
what are the 3 categories of MI
transmural
subendocardial
regional
pathogenesis of a subendocardial MI
At the surface the epicardial has a direct supply of blood and the endocardial has a supply of blood from smaller infiltrating arteries and diffusion, however the space in-between is poorly perfused (subendocardial region)
what 2 factors cause the subendocardial to infarct
Stable athermanous occlusion of the coronary circulation
An acute hypotensive episode
what are the main blood markers of myocytes damage and which ones are used rottenly in clinic
Raised Troponin-most common measure- detectable from 3 hrs and peaks at 12hrs- present for unto 7 days.
Creatine Kinase
detectable from 2-3hrs and parks between 10-24hrs- present for 3 days, 3 subtypes
Myoglobin peak at 2hrs
LDH peaks at 3 days and is detectable for 14 days
Aspartate transminase
what conditions is troponin raised in excluding MI
pulmonary embolism, heart failure, & myocarditis.
what damage does creatinine kinase show excluding MI
skeletal muscle damage
what damage does myoglobin show excluding MI
skeletal muscle damage
what damage does aspartate transaminase show excluding MI
liver damage
what is the mechanism of action of troponin.
binds to actin to prevent contraction,
Ca2+ ions allow troponin to release tropomyosin and therefore bind to actin.
most common prognosis post MI
cardiac death within 1-2 hrs.
complications of MI
Arrhythmias, ventricular fibrillation, Ischaemic pain, Left ventricular failure, shock, pericarditis, cardiac mural thrombus or emboli, DVT, PE, myocardial rupture, ventricular aneurysm, autoimmune pericarditis (dressler’s syndrome), pleurisy, ventricular wall rupture, infarct extension, haemopericardium, mural thrombus.
define mural thrombus
layers of organised fibrin in the wall of the myocardium, which are unstable and can dislodge into circulation.
what cause chronic ischaemic heart disease
Coronary artery atheroma produces relative myocardial ischemia & angina pectoris on exertion
what type of genetic defect is familial hypercholesterolemia
autosomal dominant.
commonest gene mutations familial hypercholesterolemia
Low density lipoprotein receptor gene
Apolipoprotein B
what is the difference between homozygous and heterozygous familial hypercholesterolaemia
and which has a better prognosis
- Homozygous- no functioning liver LDL receptors.
- Heterozygotes – Still have some functioning liver LDL receptors
heterozygous has a better prognosis.
symptoms of familial hypercholesterolaemia
xanthomas- tendons, perioccular, corneal arcus
atheroslerosis
treatment of familial hypercholesterolaemia
statins
Treatment of homozygotes is more complex and less effective
what is classed as abnormally high blood pressure
140/90
what are the 2 types of hypertension and which is more common
primary and secondary hypertension.
what are the main causes of primary hypertension (congenital)
cardiac baroreceptors don't function. RAS breakdown kinin-kallikrekin system breakdown Naturetic peptides adrenergic receptor system autocrine factor produced by blood vessels autonomic nervous system.
pathogenesis of all primary hypotension involves a increased net balance of what chemical/food
salt.
pathogenesis of primary hypertension
increased intravascular volume due to renal salt absorption, increased cardiac output.
tissue perfusion exceeds metabolic demands, leading to auto-regulation of bloodflow in tissues. this results in steady state haemodynamic pattern of elevated blood pressure with increased systemic vascular resistance and normal cardiac output.
Renal causes of secondary hypertension.
– Acute glomerulonephritis – Chronic renal disease – Polycystic kidneys – Renal artery stenosis – Renal artery fibromuscular dysplasia – Renal vasculitis – Renin – producing tumour
Endocrine causes of secondary hypertension
– Adrenocortical hormones (Cushing syndrome, primary aldosteronism, congenital adrenal hyperplasia, liquorice ingestion)
– Exogenous chemicals (glucocorticoids, oestrogen including pregnancy and oral contraceptives, monoamine oxidase inhibitors, amphetamines, cocaine)
– Phaeochromocytoma
– Acromegaly
– Hypothyroidism
– Hyperthyroidism
– Pregnancy – preeclampsia if severe
cardiovascular causes of secondary hypertension
– Coarctation of the aorta
– Polyarteritis nodosa
– Increased intravascular volume
– Increased cardiac output
when is the renin angiotensin system activated, when BP is low or high.
BP is low
where is renin synthesised
juxtaglomerular apparatus in the wall of the afferent arterioles of the kidney
what is the function of renin
cleaves angitensinogen to angiotensin 1.
in which organ is angiotensin I converted to angiotensin II
lungs
what is a major side effect of ACE inhibitors
chronic cough
main function of angiotensin II
Potent natural vasoconstrictor
stimulate aldosterone production.
main function of aldosterone
renal action cause sodium and water retention
circulating blood volume therefore increases
what are the consequences of renal artery stenosis
reduced blood pressure in the kidney
Juxtaglomerular apparatus stimulated to produce renin
Renin-angiotensin system stimulates adrenal cortex zona glomerulosa cells to produce aldosterone
define co-arctation of the aorta
Congenital narrowing of the aorta, usually distal to the origin of the left subclavian artery
how is coarctation of the aorta detected.
- Detected by difference in BP between the arms and legs- low BP in legs but normal in arms.
- Characteristic chest X-ray
how is coarctation of the aorta treated
surgically correctable
what is conn’s syndrome
excessive aldosterone secretion
what is the most common cause of conn’s syndrome
adrenocortical adenoma
how is conn’s syndrome diagnosed
CT scan of adrenals in presence of these metabolic abnormalities
what chemicals are retained and which chemicals are lost in Conn’s syndrome
Renal sodium and water retention.
Potassium loss
what are the side effects of excessive potassium loss
Muscular weakness, cardiac arrhythmias, parasthaesesia, metabolic alkalosis
define phaechromocytoma
tumour of the adrenal medulla
common symptoms of phaechromocytoma
pallor, headaches, sweating, nervousness, hypertension
how is phaechromocytoma diagnosed
24hr urine collection for adrenaline metabolites
treatment for phaechromocytoma
remove adrenal medulla.
Cushing’s disease.
Overproduction of cortisol by the adrenal cortex.
effects of cortisol overproduction
– Potentiating sympathetic nervous system activity.
– Mineralocorticoid action on the kidneys, thus causing hypertension.
Cause of Cushing’s disease.
– Adrenocortical neoplasm usually an adenoma.
– A pituitary adenoma
–paraneoplastic effect of other neoplasms (particularly small cell lung carcinoma) producing adrenocorticotrophic hormone that stimulates the zona fasciculata cells of the adrenal cortex to produce cortisol
what 3 organs does hypertension severely effect
heart, renal and brain.
pathogenesis of hypertensive heart disease
– Systemic hypertension leads to increased left ventricular blood pressure
– Initially left ventricular hypertrophy- recognized cause of cell death.
– When the pressure is too great the left ventricle fails to pump blood at a normal rate and dilates.
what renal changes occur due to systemic hypertension
– Vascular changes- arterial intimal fibroelastosis, and hyaline arteriosclerosis.
– Slow deterioration in renal function leading to chronic renal failure- due to damage and scarring in the intima.
what are the common conditions which occur in the brain due to hypertension
- Athermanous plaque can rupture.(intracerebral haemorrhage)
- Berry aneurysm (inherited) of the Circle of Willis (subarachnoid haemorrhage)
- Massive basal ganglia haemorrhage
- Lacunar infarct.
define hypertensive crisis
rapid rise in BP (increased risk of stroke).
what blood pressure reading shows hypertensive crisis
BP 180/120mmHg
clinical signs of hypertensive crisis
- Renal failure
- Retinal haemorrhages
- acute hypertensive encephalopathy
what are the clinical symptoms of acute hypertensive encephlopathy
confusion, vomitting, convulsions, coma and death
what are the causes of pulmonary hypertension
loss of pulmonary vasculature- Chronic obstructive lung disease, pulmonary interstitial fibrosis, pulmonary emboli and thrombosis, under ventilated alveoli
secondary to left ventricular failure
Systemic to pulmonary artery shunting
Primary or idiopathic
risk factors for cardiovascular disease
- Gender
- Hypertension
- Smoking
- High blood cholesterol
- Low blood high density lipoproteins
- Diabetes
- Sedentary lifestyle
- Obesity – especially central obesity
- High alcohol use
- Ethnicity – south Asian
what study calculates an individual’s risk of cardiovascular disease based on assessment of multiple risk factors.
The Framingham Heart Study
risk assessment methods for cardiovascular disease include
- SCORE
- QRISK2
- Joint British societies risk prediction charts.
