Heart Failure: Clinical Management Flashcards
What is heart failure?
inability to sustain a cardiac output sufficient to provide for their metabolic requirements are normal cardiac filling pressure
What are some clinical signs of inadequate cardiac output?
- exercise intolerance
- syncope
- pallor
- cold extremities
- signs of hypotension (lethargy, depression)
Whare are some clinical signs of excessive cardiac filling pressure?
signs of venous congestions
- tachypnea, dyspnea (pulmonary congestion, pleural effusion)
- ascites
What’s the gold standard for diagnosing heart failure?
CXR
- cardiomegaly
- pulmonary venous congestion
- alveolar pattern
How does heart failure affect the preload?
it may increase the preload due to fluid retention
Which drugs would be beneficial in patients with signs of congestion?
- diuretics
- venodilators
How does heart failure affect the afterload?
sympathetic nervous system and RAAS activation –> increase in afterload
Which drugs would be beneficial in patients excessive afterload?
vasodilators
Which drugs would be beneficial in patients with abnormal myocardial contractility?
positive inotrope
What drugs can improve cardiac filling?
lusitropic drugs –> sympathomimetic agents and calcium channel blockers
What are some clinical signs of patients with excessive preload?
- pulmonary edema (dyspnea)
- pleural effusion (dyspnea)
- ascites (respiratory compromise)
What’s the first choice in diuretics?
furosemide
If a patient is refractory to furosemide, what are the next options?
- can add in thiazide or spironolactone
- or switch to torsemide
What’s the MOA of furosemide?
- acts at the Loop of Henle, ascending limb
- blocks the Na/K/2Cl co transporter
- up to 25% Na excretion
What’s the MOA of thiazide?
- acts at the distal tubule and connecting segments
- blocks the Na/Cl carrier – ie. inhibits sodium reabsorption
- up to 5% Na excretion
What’s the MOA of K-sparing diuretic?
- acts at the collecting tubules
- aldosterone antagonist
- up to 2% Na excretion
What is a unique side of spironolactone in cats?
cutaneous adverse drug reactions
How is spironolactone best used?
- by itself it’s not a very potent natriuretic
- best used along side a loop diuretic
- but it’s aldosterone antagonism has benefits beyond being a diuretic
How is thiazide best used?
along side with loop diuretic and K-sparing diuretic to provide “sequential nephron blockade”
What are the 3 common complications of diuretics?
- volume depletion
- reduction in cardiac output
- electrolyte abnormalities – hypokalemia, hyponatremia
How does hypokalemia develop in the face of diurectics?
the homeostatic mechanism in response to increased Na+ and water loss is more vigorous Na+ and water retention
- Na+ retention = K+ loss in the distal nephron
- therefore, hypokalemia develops, which is more common with the loop diuretics
how does hyponatremia develop in the face of diurectics?
Vasopressin release
- free water retention = dilution of Na+ = hyponatremia
How should abnormalities with diuretics be monitored?
baseline, and 10-14d later –> urea, creatinine, electrolyte levels
What’s an example of a venodilator?
nitrate venous dilators: nitroglycerine
- cutaneous ointment
- gains tolerance quickly
What are some complications of venodilator?
drop in blood pressure –> syncope, weakness, hypoperfusion
- watch in cats with hypertrophic cardiomyopathy
How is nitroprusside used?
it’s a balanced vasodilator
- good for acute, ICU setting –> CRI, need to protect from light
- rapid, profound action –> need to monitor blood pressure
- gain tolerance quickly
- cyanide = metabolite, limits cumulative use
How is angiotensin converting enzyme inhibitors (ACEi) used?
- usually alongside a diuretic to minimize the effects of RAAS activation
- not a very potent vasodilator
- more beneficial in chronic rather than acute setting
How is amlodipine used?
it’s a calcium channel blocker
- good for cats with systemic hypertension
- may be beneficial for dogs with mitral valve regurgitation
- probably given as 2nd or 3rd line vasodilator if patient refractory to ACEi or pimobendan
How is diltiazem used?
calcium channel blocker
- also a lusitrope in cats
- used as an antiarrhythmic in dogs
Which drug can be used for pulmonary vasodilation? What’s the MOA?
Sildenafil
- it’s the phosphodiesterase V inhibitor
- reduces pulmonary vascular resistance
- can be used in dogs with severe degenerative mitral valve disease
- pimobendan can be used as well
What’s the MOA of dobutamine?
It’s a inotrope and lusitrope
- block beta-1 receptor –>enhance myocardial contraction and rate of relaxation
- sympathomimetic agent
- only given as CRI – so in hospital use only
- high doses can lead to arrhythmia
What’s the MOA of pimobendan?
Inodilator
- phosphodiesterase inhibition and calcium sensitization
- useful in DCM and DMVD
- may be helpful for cats with hypertrophic cardiomyopathy
What’s the aim of resting respiration rate for dogs/ cats with heart failure?
<40 breaths per minute
