6-cardio Flashcards
why can diuretics be good for heart failure (3)
relieve oedema, reduce work load, may have vasodilatory action
name two diuretics used in heart failure
thiazides, furosemide
what do thiazides do
diuretic, cause K+ loss
how does furosemide work
diuretic, causes K+ loss
what type of diuretic is furosemide
“high ceiling”, aka loop diuretics
what is spironolactone
K+ sparing diuretic
how does spironolactone work
aldosterone antagonist
where is aldosterone released from
adrenal cortex
what are the net effects of aldosterone
renal K+ loss, Na+ retention, water retention
what are the net effects of spironolactone
renal K+ retention, renal Na+ loss, renal water loss
what are the 3 major effects of a vasodilator on a NORMAL patient
dilate veins, dilate arterioles, increased heart rate
why does heart rate increase when vasodilators are given to normal patients (mechansim)
veinous dilation causes decreased preload which leads to decreased CO. dilation of arterioles leads to decreased arterial presure and decreased afterload. net effect: decreased CO and arterial pressure decreases BP, activating baroreceptors and increased HR
what is amyl nitrate (poppers)?
a recreational drug that is a fast acting NO donor, resulting in vasodilation
what is the net effect on BP and HR with vasodilators (in healthy subject)
hypotension and tachycardia
why does afterload increase during heart failure
compensatory sympathetic reflexes + increased angiotension = arteriolar constriction
what does high afterload do to output of a failing heart
it may limit output
why does CO increase when heart failure patients are given vasodilators?
less afterload so the heart will have an easier time pumping out blood
what happens to BP and HR when heart failure patients are given vasodilators? why?
BP doesn’t fall, no reflex tachycardia since the decreased peripheral resistance is balanced out by increased CO
where is angiotensinogen released
liver
where is renin released
kidneys
where does angiotensin converting enzyme come from
lungs
what does ACE do
convers angiotensin 1 into angiotensin2
what does renin do
converts angiotensinogen into andgiotension 1
what are the two major effects of angiotensin II
increase aldosterone release, vasocontriction
what are 4 main effects of ACE inhibitors
vasodilation
decreased aldosterone production
K+ retention
H2O and Na+ loss
what do ACE inhibitors do to bradykinin
prevents its catabolism
what is the role of bradykinin
potent activator of NO release from endothelium, resulting in vasodilation
list 3 side effects of ACE inhibitors
dry cough, angioedema and tase disturbances
what causes side effects of ACE inhibitors
they prevent breakdown of bradykinin which causes dry cough when acting in lungs
name 2 ACE inhibitors
enalapril and captopril
what is the mechanism of enalapril and captopril
ACE inhibitor, stop AG2 synthesis, increased Na+ and water loss
what are the physiological effects of ACE inhibitors
lower afterload, lower preload, incrased CO. also relieve edema by encouraging NA+/H2O loss
what receptor does SARS-CoV-2 use to gain entry to cells
ACE2 receptor
why are ACE inhibitors and ARBs speculated to worsen COVID-19 disease progression?
ACE inhibitors and ARBs tend to upregulate ACE2 expression
what are 2 drugs classes that are often combined to treat heart failure
ACE inhibitor and diuretic
why is it good to use low doses of both ACE inhibitor and diuretic instead of a high dose of one drug?
you get additive therapeutic effects and less side effects (sometimes side effects cancel out)
which side effects cancel out with ACE inhibitor and diuretics?
thiazide diuretics promore K+ loss and ACE inhibitors promote K+ retention, resulting in normal K+
name 3 angiotensin 1 receptor blockers (ARBs)
losartan, candesartan, telmisartan
which have more side effects: ACE inhibitors or ARBs?
ACE inhibitors
why do ARBs have less side effects than ACE inhibitors?
ARBs do not result in increased bradykinin levels
what class of drugs are amrinone and milrinone
phosphoriesterase inhibitors
what are the physiological effects of amrinone and milrinone
increase contraction of the heart, reduce contraction of smooth muscle
how do beta agonists work on cardiac muscle
cAMP, PKA, increase Ca++ through L type
is myocin light chain kinase in heart
no
how do B2 agonists cause vascular smooth muscle relaxation
elevated cAMP inactivates MLCK by phosphorylating it so then it cant contract
what is hypertension
elevated peripheral resistance resulting in a resting BP of 140/90
what can hypertension lead to
heart failure, strok, kidney damage
what are 4 therapeutic approaches to high BP
- diuretics
- sympatholytic agents
- direct vasodilators
- ACE inhibitors/ARBs (drugs that block angiotensin)
how can diuretics be used to treat hypertension
promote hypertension
depleting Na+ reduces blood vessel stiffness
vasodilatory action
thiazides inhibit reabsorption of which ions? where?
NaCl in the distal convoluted tubule
what is propanolol
beta 1 and 2 receptor antagonist
what is metoprolol
b1 selective antagonist
why can metoprolol be better than propranolol
acute vasodilatory action from b2 receptors may reduce effectiveness ( you dont wanna block those )
what are 4 main things that beta blockers do
- inhibit renin release by NA
- inhibit presynaptic beta receptors that increase NA release
- reduce sympathetic outflow (possible actions in CNS)
- slows HR during exercise and stress
name 4 vasodilators used to treat hypertension
hydralazine
nitroprusside
verapamil
nifedipine (DHPs)
what does hydralazine do (3)
arteriolar vasodilation, lowers BP and reflex tachycardia
what do you usually combine with hydralazine and why
beta blocker to help prevent the reflex tachycardia
what is nitroprusside? when is it used?
powerful arteriolar and venous vasodilator used in hypertension emergencies
name two Ca2+ channel blockers used to treat hypertension
verapamil
nifedipine (and other DHPs)
what are 3 agents that block the production or action of angiotensin
captopril
enalapril
losartan
what is captopril
ACE inhibitor
what is enalapril
ACE inhibitor
what is losartan
angiontensin receptor blocker
does captopril make the dry cough
yes
does enalapril make the dry cough
yes
does losartan make the dry cough
no