Cardio - Treatment of HF Flashcards
What pathophysiological parameters can we alter pharmacologically to treat HF?
Increase inotropy, decrease preload, decrease afterload, optimize HR, blunt RAAS, blunt SNS
What are the top 3 drugs we can use to decrease preload?
Furosemide, Spironolactone, Hydrochlorothiazide
What is the trade name for furosemide?
Lasix or Salix
What is the trade name for Spironolactone?
Aldactone
What is the trade name for Pimobendan?
Vetmedin
What drugs are considered diuretics?
Furosemide, Spironolactone, Hydrochlorothiazide
What drug class are weak diuretics and why?
Carbonic anhydrase inhibitors - weak due to increased Na resorption distally (PCT)
(Not really used as diuretics)
Where do loop diuretics act?
Ascending Loop of Henle
What is the mechanism behind loop diuretics?
Act on the Na/K/2Cl co-transporter to block it, therefore allowing electrolytes to remain in the lumen and be excreted in the urine along with water
Where do thiazide diuretics act?
DCT
What is the mechanism behind thiazide diuretics?
They block resorption of the Na/Cl co-transporter, causing loss of Na and Cl into the lumen - they are excreted out
Where do K+ sparing diuretics act?
Distal tubule/Collecting duct
What is the mechanism behind K+ sparing diuretics?
They block aldosterone, so you get less of the Na/H antiporter; Na is excreted and K+ is kept (“spared”) in the blood
What type of diuretic is furosemide?
It is a loop diuretic
What type of diuretic is hydrochlorothiazide?
thiazide diuretic
What type of diuretic is spironolactone?
K+ sparing diuretic
In what order would you choose a diuretic in the face of CHF?
Furosemide > Spironolactone > Hydrochlorothiazide
What are potential side effects of furosemide?
Activates RAAS (need ACEi), azotemia, hypokalemia, metabolic alkalosis, hypochloremia, hypomagnesemia
What are potential side effects of spironolactone?
Azotemia, hyperkalemia, facial dermatitis (cats)
What are the side effects of hydrochlorothiazide?
Azotemia, hypokalemia, hypercalcemia
What diuretic is the most effective at diuresis?
Furosemide
What diuretic activates RAAS and which one blocks RAAS?
Furosemide activates RAAS
Spironolactone blocks RAAS
What are the 5 drug options we have to decrease afterload?
Enalapril/Benazepril, nitroprusside, amlodipine, hydralazine, sildenafil
What is the general mechanism of drugs that decrease afterload?
They are vasodilators
What drug class are enalapril/benazepril in?
ACE inhibitors
What drug class is hydralazine in?
They increase cGMP
What drug class are nitroprusside and nitroglycerine in?
They are nitrates
What drug class is amlopidine in?
Ca channel blocker
What drug class is sildenafil in?
PDE-V inhibitor
What is the selectivity of vasodilation of enalapril/benazepril?
Balanced vasodilator (dilates arteries and veins to some degree)
What is the selectivity of vasodilation of hydralazine?
Arteriodilator
What is the selectivity of vasodilation of nitroprusside?
balanced vasodilator
What is the selectivity of vasodilation of nitroglycerine?
venodilator
What is the selectivity of vasodilation of amlopidine?
arteriodilator
What is the selectivity of vasodilation of sildenafil?
pulmonary arteriodilator
What is the indication for use of enalapril/benazepril?
chronic CHF (always), proteinuria
What is the indication for use of hydralazine?
Acute severe CHF
What is the indication for use of nitroprusside?
Acute severe CHF (CRI)
What is the indication for use of nitroglycerine?
Acute severe CHF (topical paste)
What is the indication for use of amlopidine?
Systemic hypertension or severe chronic CHF
What is the indication for use of sildenafil?
Pulmonary hypertension ONLY
What are side effects of enalapril/benazepril?
Azotemia/AKI, hypotension
What are side effects of hydralazine?
Hypotension
What are side effects of nitroprusside/nitroglycerine?
Nitrate tolerance, cyanide toxicity, hypotension
What are side effects of amlopidine?
Gingival hyperplasia (dogs), hypotension
What are side effects of sildenafil?
Hypotension, inguinal/ear tip flushing
What 2 vasodilators are given mainly in the hospital setting?
nitroprusside and nitroglycerine
What 3 drugs are used to increase inotropy?
Pimobendan, Dobutamine, Digoxin
What mechanism does Dobutamine utilize?
It is a ß-adrenergic agonist; binds to ß1 receptor, causing a cascade that results in PKA causing Ca influx into the cell
What mechanism does Pimobendan utilize?
It is a Ca sensitizer, positive inotrope, and vasodilator;
It inhibits phosphodiesterase III to increase cAMP, and sensitizes actin/myosin to Ca –> increase inotropy
What mechanism does Digoxin utilize?
It increases IC Ca by acting on 2 different pumps:
- Binds Na/K ATPase (normally 3Na out, 2K in) and paralyzes it so that it can no longer send Na out of the cell
- Works on the Na/Ca exchanger; Na buildup powers this exchanger, sending excess Na out and bringing Ca in –> extra Ca binds actin/myosin
Digoxin is used only in CHF with _____ _____.
atrial fibrillation
What generally does Digoxin do to the heart, other than increasing inotropy?
Decreases HR
What inotrope is used in the 1st line for CHF?
Pimobendan
What effect does Pimobendan have on HR?
No change
What are the side effects of Pimobendan?
Anorexia (rare), pro-arrhythmic (humans)
What effect does Dobutamine have on HR?
Mild increase
What is the indication for using Dobutamine and how is it administered?
Cardiogenic shock - IV CRI only
What are the side effects of Dobutamine?
Vasoconstriction (high doses), ventricular arrhythmias
What effect does Digoxin have on HR?
decreases it
What is the specific indication of use of Digoxin and in what species?
atrial fibrillation rate control in dogs only
What are the side effects of Digoxin?
Vomiting/diarrhea, ventricular arrhythmias, bradycardia
The therapeutic index of Digoxin is _____.
low
What 3 drugs can be used to optimize HR?
Digoxin, Diltiazem, Atenolol
What HR is used to optimize CO in dogs?
~150 - 160 bpm
What HR/pattern do most dogs that are in heart failure have?
Sinus tachycardia ~160 bpm
What eventually happens when the HR in dogs goes above 160?
The heart is beating so fast that they are no longer increasing CO
What does optimization of HR in HF mean?
Treating tachyarrhythmias (or bradyarrhythmias) that compromise CO
What drug type would you use to treat rapid atrial fibrillation?
negative chronotrope
What drug type (and give the names) would you use to treat bradyarrhythmias?
Positive chronotrope;
Atropine, theophylline, or artificial pacing
What are the negative chronotropes?
Diltiazem, Digoxin, Atenolol
What is the MOA of Diltiazem?
Ca channel blocker (slow conduction at AV node)
What effect does Diltiazem have on contractility?
Mild decrease
What is the specific indicatino for using diltiazem?
It is most effective at lowering HR
What are the side effects of diltiazem?
GI upset, bradycardia, hypotension
What is the MOA of Digoxin?
Vagomimetic (slow conduction at AV node)
What is the MOA of Atenolol?
B-adrenergic blocker (slow conduction at AV node)
What effect does Digoxin have on contractility?
Mild increase
What effect does Atenolol have on contractility?
Decreases it
What is the specific indication for Digoxin?
It is a good drug to use in the setting of CHF
What is the specific indication for Atenolol?
ONLY if started prior to CHF
What are side effects of Digoxin?
Vomiting/diarrhea, ventricular arrhythmias, bradycardia
What are side effects of atenolol?
Bradycardia, hypotension, bronchospasm
What are the 3 drugs that blunt RAAS/SNS?
Enalapril/benazepril, Spironolactone, Atenolol
What stimulates renin release?
Decreased renal perfusion, increased sympathetic tone, decreased Na to macula densa
What 2 aspects of RAAS are we blocking with drugs?
- Angiotensin II (aldosterone release, SNS stim, hypertrophy of heart/vessels)
- ACE
Angiotensin II, aldosterone, and SNS stimulation are _____ (AKA bad) because they cause _____ and _____.
CARDIOTOXIC, fibrosis, remodeling
What is the order of choice for neurohormonal modulators?
Enalapril/benazepril = always in chronic CHF
Spironolactone = usually in chronic CHF
Atenolol = ONLY if started prior to CHF
What is the acronym for treatment of ACUTE CHF in dogs?
FOPS
Furosemide, Oxygen, Pimobendan, Sedation
(+/- dobutamine and nitroprusside if doing very poorly)
What is the acronym for ACUTE CHF in cats?
FOPS +/- T
Furosemide, Oxygen, Pimobendan, Sedation, +/- Thoracocentesis
(+/- dobutamine)
Why would you want to perform a thoracocentesis in a cat with acute CHF?
Because it probably has pleural effusion
What is the acronym for CHRONIC CHF in dogs?
Dogs Are For Special People
Dietary Na restriction, ACEi, Furosemide, Spironolactone, Pimobendan
(+/- Sildenafil if pulmonary hypertension)
(+/- Diltiazem+Digoxin if atrial fibrillation)
What is the acronym for CHRONIC CHF in cats?
Don’t Forget About Cats, Please
Dietary Na restriction, Furosemide, ACEi, Clopidogrel, Pimobendan
(+/- Atenolol if started before CHF)
Why would you consider clopidogrel as part of your treatment of chronic CHF in cats?
Because of possible clot formation (HOCM)
What is the frequency of tx of HF meds?
BID-TID
What diet changes should be condiered for patients in HF?
Moderate Na restriction (50-80mg per 100kcal), protein/calories to avoid cachexia, supplements such as fish oil, K, mg, taurine, carnitine
What exercise/activity modifications should be considered in patients in HF?
Allow pets to self-regulate and avoid strenuous activity
What are the 2 goals of HF tx?
Quantity of life (survival) and Quality of life
