Flashcards in Hypertension Deck (43):
What is the resting BP in hypertension?
SBP > 140mmHg
DBP > 90mmHg
Organs that will be damaged by hypertension
heart, brain, retina, kidney, dissecting aortic aneurysm
Tissues damaged due to artherosclerosis
Coronary, cerebral vessels, carotids
What two broad changes occur in the cardiovascular system in response to hypertension?
Cardiac and vascular hypertrophy
Lifestyle changes to treat hypertension?
regular exercise, reduced dietary salt, decreased alcohol, lower weight
Groups of commonly used antihypertensive drugs
angiotensin converting enzyme inhibitors and angiotensin antagonists
calcium channel blockers
diuretics (thiazides, loops, K+ sparing)
Where does angiotensinogen come from?
what converts angiotensinogen into angiotensin I?
renin from juxta-glomerular cells
what converts angiotensin I to angiotensin II?
ACE (lungs and elsewhere)
What does angiotensin II cause?
vasoconstriction (has direct effect on lumen diameter), aldosterone output, sodium and water retention
what converts bradykinin to inactive products?
ACE (lungs and elsewhere)
where are angiotensin I and II found?
in the bloodstream
What do ACE inhibitors do? -opril, -april
- prevent angiotensin II formation and inhibit bradykinin breakdown, resulting in lower peripheral resistance and sodium and water excretion
What are the indications for use of ACE inhibitors?
hypertension, heart failure, preserve renal function in diabetes (diabetic nephropathy)
contraindications for ACE inhibitors?
- less effective in patients of African origin
- renal failure if there is also renal artery stenosis
- avoid in pregnancy
Common side effects of ACE inhibitors?
cough (from high bradykinin), headache, marked hypotension (start with low dose), hyperkalaemia (beware of K+ supplements or K+ sparing diuretics)
infrequent side effects of ACE inhibitors?
rash/itch, taste disturbances, angioedema
Example of ACE inhibitor?
Example of an angiotensin receptor blocker (ARBs)?
What do ARBs do?
are angiotensin I receptor antagonists: inhibit angiotensin -induced vasoconstriction and aldosterone output; effect is reduced total peripheral resistance and increased Na+ and water excretion *no dry cough as seen in ACE inhibitors
What are the indications for use of ARBs?
hypertension, heart failure, diabetic nephropathy, for patients intolerant to ACE inhibitors e.g. cough
adverse effects of ARBs?
hypotension (less than ACE inhibitors), hyperkalaemia, avoid in pregnancy, beware of renal artery stenosis
What do calcium channel blockers do?
block L-type (voltage operated) calcium channels, reduces Ca2+ entry into the vascular/cardiac cells *not skeletal muscle, therefore there is a reduction in intracellular calcium = vasodilation and reduced cardiac contractility and reduced atrioventricular conduction
2 examples of calcium channel antagonists? Key difference between the two?
verapamil - reduces venous pressure (preload), has stronger effects on the heart
and amlodipine - reduces arteriolar pressure (afterload), stronger effects on HR (up), BP (down) and TPR (down)
what are indications for calcium channel blockers/antagonists?
hypertensions, angina, tachydysrhythmias (TDRs)
What are contraindications for calcium channel blockers?
heart failure or beta-blockers (with verapamil)
Side effects of calcium channel blockers
- cardiac depression (both rate and force reduced), bradycardia (therefore contraindicated in heart failure)
- flushing, oedema, dizziness, headache
- constipation, nausea
what do diuretics do?
- increase water and sodium excretion from the kidney
- reduce circulating blood volume in hypertension; there is an initial drop in CO and; in longer term CO and TPR return to normal levels
What do thiazides e.g. hydrochlorothiazide and indapamide act on?
Example of a diuretic?
frusemide, more potent than thiazides, used in acute scenarios
What do loop diuretics such as frusemide act on?
loop of Henle
Uses of thiazides such as hydrochlorothiazide and frusemide?
- mild to moderate hypertension
- oedema due to: 1)congestive heart failure (+/- hypertension), 2) +/- pulmonary congestion and renal or liver disease
Side effects of thiazides generally?
rash, hypokalaemia, hyperuricaemia, glucose intolerance, hyperchlesterolaemia
Side effects of loop diuretics?
- hypovolaemia: dizziness, weakness, nausea, cramps, hypotension
- hearing loss
- increased magnesium, calcium excretion
What is an important drug interaction with the use of diuretics?
Digoxin - toxicity is greatly increased
(also consider K+ supplementation or combination with K+ sparing diuretics)
What do beta-adrenoceptor antagonists do - what are their effects?
decrease sympathetic input to the heart (therefore reduced CO and HR - and TPR to a lesser extent), inhibit renin release by decreasing Ang II levels, reduce sympathetic outflow from CNS if lipid soluble
2 examples of beta-adrenoceptor antagonists and their selectivities?
Propranolol - non selective beta 1 and 2 antagonist
Atenolol - beta 1 selective antagonism
Clinical uses for beta adrenoceptor antagonists?
angina, post myocardial infarct, hypertension, dysrhythmias, clinically stable heart failure
Factors to consider when choosing a hypertensive
-patient's CV risk profile
-presence of target organ damage, renal disease, diabetes
-presence of coexisting conditions which may favour/limit use of particular classes (diabetes, respiratory)
-individual patient variability to different classes
-interactions with other co-prescribed drugs
Most effective combination for hypertension?
ACE inhibitor or ARB
+ calcium channel blocker
Other effective combination therapies?
- ACE inhibitor/ARB + thiazide diuretic esp. in heart failure or post stroke (low dose thiazide diuretic for people aged 65+)
- ACE inhibitor/ARB + beta-blocker esp. post MI or heart failure
- beta-blocker + dihydropyridine calcium channel blocker esp. coronary heart disease
- thiazide diuretic + Ca2+ channel blocker
- thiazide diuretic + beta-blocker *not recommended in people with glucose intolerance, metabolic syndrome or established diabetes
In newly diagnosed hypertension, is it best to start with mono or combination therapy?
One drug to start, then 2 then 3. If after 3, target BP is still not reached, then refer to a specialist.