Heart Failure Flashcards
Define low output heart failure / “Forward” HF
ventricular dysfunction resulting in poor tissue perfusion (↓ CO) & arterial hypotension (↓ BP)
Define CHF / “Backwards” HF
cardiac malfunction resulting in ↑ pulmonary venous or systemic venous pressures
Which usually precedes the other: low output heart failure or congestive heart failure
CHF almost always precedes low output HF
What is the expected blood pressure (High vs Low vs Normal) for the following:
congestive heart failure:
low output heart failure:
congestive heart failure: normal BP
low output heart failure: ↓ BP
True or False: patients with CHF usually appear BAR, whereas patients with low output heart failure appear QAR
TRUE
BP = _____ X _____
BP = CO x SV
List the harmful effects of Angiotensin II
- Free radicals cause cell death and fibrosis resulting in myocardial dysfunction (can’t fill or contract)
- Increased vasoconstriction causes increased afterload and decreased SV and CO
List the beneficial effects of Angiotensin II
- Increased vasoconstriction and sympathetic tone results in increased BP and increased CO
- Triggers aldosterone to increase Na+ and H20 which increases blood volume and CO
In concentric hypertrophy, sarcomeres are added in __________
parallel
In eccentric hypertrophy, sarcomeres are added in __________
series
What symptoms and CS do you expect to see with L-sided CHF?
- Syncope
- Coughing (Dogs>cats)
- Hypoxemia (dec. gas exchange from lungs)
- Exercise intolerance
- Tachypnea (inc resp rate) to try and compensate/ Dyspnea
- Pulmonary edema
Cats: pleural effusion causing ABD distention
What symptoms and CS do you expect to see with R-sided CHF?
- ABD and jugular distention
- Exercise intolerance
- Cough (Dogs>cats)
- Tachypnea/Dyspnea
- Syncope
- Diarrhea if peritoneal effusion
PE abnormalities in a dog with L-sided CHF?
- Tachypnea/Dyspnea
- Inc HR (tachycardia)
- Crackles/wheezes
- Muscle loss
- Abnormal heart sounds
PE abnormalities in a dog with R-sided CHF?
- Inc HR (tachycardia)
- Jug vein distension
- +/- Tachypnea/Dyspnea if pleural effusion
- Decreased or absent lung sounds if pleural effusion
- ABD distension due to peritoneal effusion
- Abnormal heart sounds
PE abnormalities in a cat with R-sided CHF?
- Inc HR (tachycardia)
- Jug vein distension
- Tachypnea/Dyspnea due to pleural effusion
- Decreased or absent lung sounds due to pleural effusion
- +/- ABD distension due to peritoneal effusion
PE abnormalities in a cat with L-sided CHF?
- Tachypnea/ +/-Dyspnea
- Inc HR (tachycardia)
- Increased bronchovesicular sounds/Crackles/wheezes if pulmonary edema ORRR decreased/absent lung sounds if pleural effusion
- Muscle loss
- Abnormal heart sounds
CS and PE abnormalities of Low Output heart failure
- Pale mucous membranes
- Hypothermia
- Weak femoral pulses
- Weakness/collapse
- Tachycardia (inc HR)
- Abnormal heart sounds
- Muscle loss
(Bolded shows differences between low output heart failure vs CHF)
List 2 tests you would want to do in order to diagnoses low output heart failure?
- Blood pressure (will be LOW)
- Lactate (will be HIGH due to hypoxemia and anaerobic metabolism)
3 Goals of heart failure therapy?
- Relieve congestion
- Improve cardiac output
- Prevent progression
The first step of HF therapy is to relieve congestion. How is this done?
Decrease ventricular filling pressure by:
- Decreasing blood volume (preload): Give diuretic drug to dec. preload
- Decrease venous return to the heart (preload): Give venodilating drugs
- Increase forward flow (CO)
Which drug is given during heart failure therapy to decrease preload?
Furosemide!!! (loop diuretic)
- decreases blood volume back to the heart which slows down accumulation and congestion
Which drugs is given during heart failure therapy to improve CO and relieve congestion in the case of a systolic dysfunction?
- Positive inotrope to increase ventricular contractility (Ex: Pimobendan, Dobutamine)
- Arterial dilating drugs to decrease afterload
Which drug is given during heart failure therapy to improve CO and relieve congestion in the case of a diastolic dysfunction?
- Negative chronotropic drugs to decrease HR and allow more time for filling
- Lusitropic drugs to improve ventricular relaxation and atrial function
The 3rd step of HF therapy is to prevent progression/remodeling. How is this done?
- Inhibit the deleterious neuroendocrine mechanisms (Ex: RAAS and Ang II)
Give ACE inhibitor!! Benazepril/Enalapril
What is the 1st choice diuretic for CHF in cats and dogs?
Furosemide
What is the acute/emergency administration dose of Furosemide for a dog with CHF? Cat dose?
Dog: 2-4 mg/kg IV or IM
Cat: 1-3 mg/kg IV or IM
What is the chronic/maintenance administration dose of Furosemide for a dog with CHF? Cat dose?
Dog: Start at 2mg/kg PO BID
Cat: Start at 1 mg/kg PO SID or BID
Main electrolyte imbalance seen in a patient on furosemide for CHF?
Hypokalemia
A patient on furosemide for CHF has developed tolerance. What is an alternate drug you can give?
Torsemide (loop diuretic)
- Better oral bioavailability and longer duration than furosemide
How is spironolactone a K+ sparing diuretic?
Aldosterone receptor antagonist
- Blocks Na+ reabsorption and K+ elimination
Cardiac effects of ACE inhibitors?
- Combats deleterious effects of chronic RAAS activation
- Arterial and venous vasodilator
- Cardioprotective by preventing myocardial fibrosis
Contraindications for use of ACE inhibitors?
Do not use in dehydrated, hypovolemic, or hypotensive patients
Caution with pre existing renal dz and concurrent NSAID use
List conditions that cause renal hypoperfusion
- Hypotension
- Hypovolemia
- Dehydration
- Renal disease
- Heart failure
MOA of nitroglycerin?
Venodilator
(decreases preload, used in acute tx of CHF)
MOA of nitroprusside and main use?
Arteriodilator + venodilator
(decreases afterload via artery dilation)
**Used for severe/life threatening pulmonary edema
Sildenafil MOA and main use?
Pulmonary arteriodilator
Used for pulmonary hypertension
Hydralazine MOA and main use?
Arteriodilator (reduces afterload)
True or False: Arteriodilating drugs are used in CHF to reduce preload
FALSE
Used for CHF but arteriodilators reduce AFTERLOAD
True or False: Venodilating drugs are used in CHF to reduce preload
TRUE
All of the following are arteriodilators used to decrease afterload, except?
A. Nitroprusside
B. Nitroglycerin
C. Amlodipine
D. Hydralazine
B. Nitroglycerin (venodilator, decreases preload)
List the arteriodilators
- Nitroprusside
- Hydralazine
- Amlodipine
- Sildenafil (pulmonary arteriodilator)
- ACE inhibitors (indirectly)
What effects does Pimobendan have that makes it useful in treatment of CHF?
Positive inodilator - improves contractility and decreases afterload
Main use of digoxin?
Weak, positive inotrope used as an anti-arrhythmic
Which of the following is NOT a positive inotrope?
A. Pimobendan
B. Amlodipine
C. Dobutamine
D. Digoxin
B. Amlodipine (arteriodilator)
- no effect on contractility, used to dec. BP
What would you prescribe to a cat in acute CHF?
- Furosemide
- Clopidogrel
(same for chronic CHF)
- +/- pimobendan, vasodilators, etc.
What would you prescribe to a dog in acute CHF?
- Furosemide
- Pimobendan if suspect systolic dysfunction or valvular regurg
- +/- positive inotrope, vasodilator, etc.
What would you prescribe to a dog in chronic CHF?
- Furosemide (dec. preload and vol to the heart, slows down congestion)
- Pimobendan if suspect systolic dysfunction or valvular regurg (increases contractility)
- ACE inhibitor (Benazepril/Enalapril) (cardioprotective, indirect vasodilator, counteracts neg effects of RAAS)
- Spironolactone (K+ sparing, cardioprotective)
Diet reccommendations for a pet in heart failure?
- Adequate calories and protein to prevent cardiac cachexia
- Omega 3 for anti-inflamm effects
List the 2 main cardioprotective drugs that reduce the deleterious effects of RAAS (fibrosis, apoptosis, necrosis)
- ACE inhibitors (Benazepril/Enalapril)
- Aldosterone antagonist (Spironolactone)
