10. Vasodilators and Diuretics Flashcards
Why is vasoconstriction important during HF?
redistributes blood flow to the brain and heart
Peripheral vasoconstriction increases ________.
afterload
What other tissues are compromised when blood is shunted away from periphery?
- kidney
- skeletal muscle
- liver
What class of vasodilators produces the most venous dilation?
nitrovasodilators
What class of vasodilators produces the least venous dilation?
hydralazine
What class of vasodilators produces the most arterial dilation?
hydralazine
What class of vasodilators produces the least arterial dilation?
nitrovasodilators
What is the MOA of organic nitrates in HF?
- biotransformation to NO
- activates guanyl cyclase to ↑ cGMP
- produces SMC relaxation
The smooth muscle relaxation produced by organic nitrates mainly has what action on the heart?
reduces preload
Organic nitrates are not approved as monotherapy for HF. (T/F)
True
What are organic nitrates often combined with to treat HF?
hydralazine
What is the only organic nitrate approved for HF?
isosorbide dinitrate
Isosorbide dinitrate is approved for what class of HF?
HFrEF Class III-IV
What is nitroprusside approved for?
acute decompensated HF
Nitroprusside is spontaneously converted to ____.
NO
What is the route of administration of nitroprusside?
IV
What is the boxed warning of nitroprusside?
prolonged infusions = high potential for cyanide toxicity
What is the infusion duration maximum of nitroprusside?
≤ 10 minutes
What is the MOA of hydralazine?
unknown
Hydralazine reduces afterload in HFrEF patients by doing what?
relaxing arterial smooth muscle
Hydralazine has the most significant effect on preload. (T/F)
False: minimal effect on preload
Hydralazine is often combined with _______ to decrease preload.
isosorbide dinitrate
What class of vasodilator is the most effective at reducing renal vascular resistance/ ↑ renal blood flow?
hydralazine
What drug can be used to counteract the renal dysfunction created by ACE inhibitors or ARBs?
hydralazine
What other vasodilators are rarely used in HF and have questionable efficacy?
- Prazosin
- CCBs
What CCBs are not recommended in systolic dysfunction and why?
- verapamil
- diltiazem
- negative inotropic effect
The treatment guidelines now recommend what with the treatment of CCBs?
avoid use of all CCBs in HF
What 2 processes contribute to extracellular fluid volume expansion?
- adrenergic stimulation
- RAAS
What is the adrenergic effect on fluid volume?
β receptor mediated release of ADH (vasopressin) from pituitary gland
What is the effect of the RAAS on fluid volume?
Ang II increases aldosterone and stimulation of thirst
What is the primary goals of diuretic therapy?
- reduce edema and pulmonary congestion by reducing preload
- reduce ventricular filling pressure
Diuretic therapy causes clinically important reduction in CO. (T/F)
False: only when there is a rapid decline in intravascular volume
In HF patients, reduction in preload decreases CO. (T/F)
False: this happens in healthy patients
How do loop diuretic produce significant diuresis?
increased urinary excretion of Na, K, Cl
What is the most widely used class of diuretics?
loop
Loop diuretics can be used as a single agent in moderate and advanced HF. (T/F)
True
What is the most significant problem with loop diuretics?
hypokalemia can precipitate life-threatening ventricular arrhythmias
What other HF drug, when combined with diuretics, can enhance arrhythmias?
digoxin
What class of diuretics can be used as monotherapy in the beginning stages of HF?
thiazide
What is the site of action of thiazide diuretics?
distal tubule
What are the potential complications of thiazide diuretics?
- ↑ excretion of K (contribute to arrhythmias)
- effectiveness reduced in patients with renal failure
What are the Na channel inhibiting K sparing diuretic agents?
amiloride and triamterene
What are the aldosterone receptor antagonist K sparing diuretics?
- spironolactone
- eplerenone
What is nesiritide?
a purified preparation of human B-type natriuretic peptide
What is nesiritide approved for?
acute decompensated HF
What is the route of administration for nesiritide?
IV
What is the mechanism of action for Ivabradine?
Blocks the iNa (slow) in the SA node to slow HR
What class of HF is Ivabradine recommended for?
class II and III with EF ≤ 35%
What are contraindications for Ivabradine?
- acute decompensated HF
- rhythm disturbances
- AV block
What 2 drugs make up Entresto?
sacubitril and valsartan
What class of HF is Entresto recommended for?
Class II – IV
Sacubitril is a prodrug that is metabolized into what?
neprilysin
What is neprilysin?
peptidase that degrades multiple endogenous peptides, including natriuretic peptides and bradykinin
