hypertension & myocardial infarction Flashcards
what is hypertension?
- raised blood pressure above a population defined norm
- sustained systolic BP > 140mmHg and diastolic BP of > 90mmHg
what is essential hypertension?
- high blood pressure that is not as a result of a medical condition
what is** secondary** hypertension?
- high BP that is caused by another medical conditon eg problems with kidneys, arteries, heart or endocrine system etc
what is malignant hypertension?
*** very high BP that comes rapidly **
* can lead to death in 1-2 years if left untreated
* often seen with renal failure & retinal haemorrhage
compare** diastolic vs systolic pressure** & what is a normal value for these?
- systolic pressure refers to the amount of pressure experienced by the arteries while the heart is beating
- diastolic pressure refers to the amount of pressure in the arteries when the heart is at rest between beats
- normal value - under 120/80mmHg
what are examples of pathologies that may cause secondary hypertension?
- renal - any cause of chronic renal failure eg renal artery stenosis
- endocrine - cushings, conn’s syndrome
- CVS
- neurologic - acute stress
what is the equation for cardiac output?
CO= HR X SV
what is the equation for BP?
BP= CO X TPR (total peripheral resistance)
what is hypertension a risk factor for?
- stroke
- CVS disease
- renal disease
what renal event may be the key initiating event in essential hypertension & why?
- reduced renal sodium excretion
- this will lead to increased fluid volume and cardiac output - which as a result will increase BP
if the BP is lowered, what system does the renal system activate?
- the renin angiotensin aldosterone system
- by releasing renin
as a result of the actions of the RAAS system in response to a low BP, what are the end effects?
- vasoconstriction
- retention of salt & water
- lead to increase in BP
what might cause mineralcorticoid excess?
cause of secondary hypertension
- aldosterone producing adenomas
- bilateral adrenal hyperplasia
- ectopic aldosterone secretion
what may cause corticosteroid excess?
cause of secondary hypertension
- cushings disease - pituitary gland tumour leading to excessive ACTH
- cushings syndrome - any other cause eg adrenal tumours, adrenal hyperplasmia, ectopic tumours releasung ACTH
what may cause growth hormone excess in the body?
cause of essential hypertension
- pituitary gland produces too much GH
what may cause catecholmine excess in the body?
cause of secondary hypertension
- tumours of chromaffin tissue of the adrenal medulla
what is thyrotoxicosis?
- high level of thyroid hormones circulating in the body
- causes increased contactile activity of heart
- increases sympathetic activity - ie can cause vasoconstriction
- will raise systolic BP
what are the vascular effects of HTN?
- accelerates atherosclerosis - ie hardening of arteries
- causes degenerative effects in vessel wall
- small vessel disease
what is arterioloscelerosis?
progressive increase in the elastic or muscular components of the vessel wall which can be induced by hypertension
what can occur to the left side vs right side of the heart as a result of HTN?
- left side - **concentric left ventricular hypertrophy ** - more common, due to response to systemic hypertension
- right side - right ventricular hypertrophy caused by disorders of pulmonary vasculature causing pulmonary hypertension
what effect can an impaired blood flow to the heart result in?
ischaemia - which if it is very severe can cause infarction (,muscle death)
what is ischaemia?
- imbalance between supply (perfusion) and demand of oxygenated blood to a tissue
- insufficient O2 and nutrients and inadequate removal of metabolites
what is infarction?
tissue death due to ischaemia
what are the risk factors for ischaemic heart disease ?
modifiable vs non mod
- modifiable
* hypertension
* smoking
* diabates
* obesity - non mod
* family history
* genetics
* age - risk increases with age
* sex- men more likely
what is angina?
- chest pain due to reduced blood flow to the heart
- due to lack of oxygen and build up of metabolites
what is stable vs unstable angina?
- stable angina -the chest pains have a trigger eg when myocardial demand outweighs the perfusion eg during exercise … relief comes with rest or medication
- unstable - chest pain is more unpredictable - could happen with or without exercise / exertion - severe and transient reduction in cornary blood flow due to plaque
what is acute coronary syndrome?
- a term that describes a range of conditions related to sudden, reduced blood flow to the heart
- eg unstable angina, acute MI & sudden death (regional myocardial ischaemia)
what is myocardial infarction & what is it caused by ?
- heart attack
- caused by a decreased or complete cessation of blood flow to a portion of the myocardium
- platelets aggregate to the plaque on the vessel wall - coagulation pathwya is activated and a thrombus develops an atheromateous plaque which evolves to occlude the lumen
what are the symptoms of myocardial infarction?
- chest pain
- LEFT arm pain
- short of breath
- sweaty
- dizzy
- rapid, weak pulse
- silent in elderly and diabetics
how can you prevent myocardial infarction?
- stop smoking
- control BP
- reduce cholesterol and weight
- control of diabetes
