Cardio Pharm Flashcards
What is heart failure?
inability to provide required physiological needs
What is congestive heart failure?
- retention of fluid secondary to heart failure
- Na+ retention, H20 follows
- “diastolic failure”
What neurohumoral factors are increased in response to decreased perfusion of tissues in heart failure?
- SNS
- RAAS
- ADH
What are the adaptive responses that occur after an increase in neurohumoral factors?
- vasoconstriction
- Na/H2O retention
- increased inotropy
What maladaptive responses occur in heart failure?
- increased afterload
- increased cardiac work
- decreased cardiac efficiency
- fibrosis
- altered signaling
What is the goal of cardio pharm?
blunt maladaptive responses the best we can
What are 2 consequences of maladaptive responses in heart failure?
- decreased ventricular compliance
- decreased systolic function
What are the three types of CHF?
- left sided CHF: pulmonary edema
- right sided CHF: ascites
- biventricular failure: ascites, pleural effusion
How do you progress from heart failure to CHF?
- reduction in compliance of ventricle
- diseased heart fills at elevated pressure
What are the three goals of pharmacologic therapy for CHF
- resolve/prevent retention of fluid
- improve quality of life
- improve prognosis
How will cardio pharm improve the quality of life in CHF patients?
- improve hemodynamic parameters
- increase exercise capacity
How will cardio pharm improve prognosis in CHF patients?
decreased morbidity and mortality
What is preload?
end diastolic pressure
What is afterload
end systolic pressure
What drugs decrease preload?
- diuretics
- venous vasodilators
How do diuretics decrease preload to treat heart failure?
decrease plasma volume
How do venous vasodilators decrease preload to treat heart failure?
increase vascular volume
What drugs decrease afterload to treat heart failure?
arterial vasodilators
How do arterial vasodilators decrease afterload to treat heart failure?
decrease systemic vascular resistance
What drugs increase pumping strength/efficiency (positive inotropy) in treatment of heart failure?
- catecholamines (epi and norepi)
- phosphodiesterase inhibitors
- calcium sensitizers
- cardiac glycosides
Where are loop diuretics secreted?
into the tubular lumen
What is the MOA of loop diuretics?
- inhibition of Na/K/2CL symporter in the thick ascending LOH
- Na/K/ Cl remain in tubule, disrupting countercurrent multiplication
What is the onset of action of loop diuretics?
rapid
What is the duration of action of loop diuretics?
relatively short
Because loop diuretics can secrete lots of Na, it is considered potent or what?
high ceiling
Describe the potency of torsemide compared to furosemide
10x more potent, lasts longer –> be cautious of dehydration
When does peak diuresis occur after oral administration of furosemide?
1-2 hours
When does furosemide effect begin to dissipate?
6 hours
When does diuretic resistance begin to develop in healthy dogs after beginning furosemide therapy?
14 days
What factors contribute to furosemide resistance?
- increased expression of co-transporters in response to aldosterone like substance
- high ceiling diuretic
What effect does furosemide have when administered IV?
venodilation prior to onset of diuretic action
What are the adverse effects of furosemide?
- hypokalemia, hypochloremic metabolic alkalosis
- dehydration
- ototoxicity in humans
Furosemide also induces notable excretion of what two compounds?
Ca and Mg
What substances may blunt the furosemide response?
NSAIDs and steroids
What class of loop diuretics is torsemide in?
pyridine-3-sulfonylurea
When does peak diuresis occur with torsemide?
1-2 hours after oral administration
When does torsemide begin to dissipate?
12 hours
When is torsemide used?
when furosemide resistance develops
What are the adverse effects of torsemide?
- hypokalemia, hypochloremic metabolic alkalosis
- dehydration
Explain the activity of torsemide in regards to aldosterone.
anti-aldosterone activity
What is the MOA of thiazide diuretics?
- directly inhibit Na/Cl cotransporter in DCT
- Na, Cl, and H2O remain in tubule
Are thiazide diuretics considered high or low ceiling?
low
When does peak diuresis and dissipation occur with thiazide diuretics?
- rapid GI absorption
- peak diuresis 1-2 hours after oral admin.
- dissipates over 6-12 hours
Thiazide diuretics can be used synergistically with what other type of diuretic?
loop diuretics
What are the adverse effects of thiazide diuretics (more likely when used with loop diuretics)?
- hypokalemia
- dehydration
What effect do thiazide diuretics have on Ca?
relative Ca-sparing effect
What two drugs are thiazide diuretics?
- hydrochlorothiazide
- chlothiazide
What is the K sparing diuretic?
spiranolactone
What is the MOA of spiranolactone?
- antagonized effects of aldosterone
- decrease Na/H2O resorption in DCT/CT
- reduction in luminal Na channel
- reduction in Na/K ATPase pump at basolateral membrane
Is spironolactone a weak or strong diuretic?
weak
Spironolactone is used in combination with other diuretics, why?
- never used for substantial diuresis alone
- can help obviate hypokalemia from other diuretics
Explain the anti-mitogenic properties of spironolactone?
- hypertrophy (cardiac and smooth muscle)
- fibrosis (myocardial and vascular)
- aldosterone-escape with ACE
Why is CHF therapy with diuretics alone should be limited to acute, relative short episodes?
- further reduction in CO and azotemia
- AKI risk
- activation of neurohumoral systems and maladaptive responses
How does diuretic therapy induce reduction in CO and pre- or intra-renal azotemia?
overaggressive diuresis without other drugs to improve cardiac performance
How does diuretic therapy induce AKI?
aggressive therapy with ace –> why you should avoid ace