pathophysiology + treatment of hypertension Flashcards
what is the equation for mean arterial pressure?
MAP (mean arterial pressure) = CO (cardiac output) x TPR (total peripheral resistance)
what is the equation for MAP involving systolic and diastolic pressure?
MAP = DP + 1/3(SP - DP)
what is the equation for cardiac output?
CO = SV (stroke volume) x HR (heart rate)
define cardiac output
amount of blood for heart can pump out in one minute
define stroke volume
amount of blood that can be effectively pumped out of the heart via the left ventricle
equation for stroke volume
SV = preload (vol of blood at the end - diastole) x afterload (resistance heart much overcome to pump) x contractility (inherent strength of the heart’s contraction)
define total peripheral resistance
resistance arteries and cells have against blood being pumped through them
how is TPR increased?
vasoconstriction
name the 3 hypertensive drug categories
ace inhibitors or angiotensin II receptor blockers (ARBs) calcium channel blockers diuretics
list the main side effects of ACE inhibitors
angiodema cough alopecia angina nausea chest pain
how do ACE inhibitors help relieve hypertension?
inhibit conversion of angiotensin I to angiotensin II, which reduces vasoconstriction
how do ARBs help relieve hypertension?
selective competitive blockers of angiotensin II at the AT1 receptor
when should you be cautious about prescribing ARBs? (specifically losartan)
severe hepatic impairment severe cardiac failue pregnancy
list main side effects of ARBs
abdominal pain hyperkalaemia hypotension renal impairment anaemia (losartan specific)
when should you be cautious about prescribing ACE inhibitors?
renal impairment
list main side effects of calcium channel blockers
peripheral oedema tachycardia dizziness palpitations
when should you be cautious about prescribing calcium channel blockers?
cardiogenic shock hepatic impairment (may need dose reduction
when should you be cautious about prescribing diuretics?
diabetes eletrolyte balance addison’s disease elderly
list main side effects of diuretics
kypokalaemia constipation electrolyte imbalance
how do diuretics help relieve hypertension?
Inhibition of Na+ and Cl- reabsorption from distal convoluted tubules by blocking Na+ Cl- symporter – stop reabsorption of water lower doses can also cause vasodilation
how do calcium channel blockers help relieve hypertension?
inhibit influx of calcium ions
what do calcium channel blockers act on?
Myocardial muscle – inhibit contractility (how well heart pumps – reducing stroke volume and therefore cardiac output) Vascular smooth muscle – coronary or systemic vascular tone reduced (vasodilation)
define ARTERIOsclerosis
thickening, hardening and loss of elasticity of arteries which gradually restricts blood flow to tissues
define ATHEROsclerosis
form of arteriosclerosis where there is development of fatty plaques and cholesterol in the wall of arteries as part of an inflammatory response
what are the parameters for the different stages of hypertension?
what are the contraindications for ACE inhibitors?
combination with aliskiren (renin inhibitor) in patients w eGFR (glomerular filtration rate)
diabetes mellitus
what are the contraindications for ABRs?
combination w renin inhibitor in pateints w reduced eGFR
diabetes mellitus
what are the contraindications with calcium channel blockers?
cardiogenic shock
significant aortic valve disease (stenosis)
unstable angina
hepatic impairment - may need dose reduction due to prolonged half-life
what are contraindications for diuretics?
addison’s disease
electrolyte imbalance
