Congestive Heart Failure Flashcards
What is heart failure?
Syndrome in which the heart is unable to meet the metabolic needs of tissues, DESPITE adequate venous return
What are the two types of heart failure?
Congestive heart failure
Low output heart failure
What is the difference between congestive and low output heart failure?
Congestive heart failure-> cardiac malfunction resulting in increased pulmonary/systemic venous pressures (“backward” or “wet”)
Low output heart failure -> severe ventricular dysfunction resulting in arterial hypotension and poor tissue perfusion (“forward” or “cold”)
T/F: In heart failure, end diastolic pressure is lower than normal
False
There are increased ventricular filling pressures
If you have increased, left sided ventricular filling pressure you will get _________ congestion
Pulmonary
If you have increased, right sided ventricular filling pressure you will get _________ congestion
Systemic
-> effusion in peritoneum or pleural cavity
What are consequences of decreased cardiac output?
Hypoperfusion
Arterial hypotension
CO = ___________x_________
CO= stroke volume x heart rate
Stroke volume = ___________ - ___________
SV =End diastolic volume - End systolic volume
What three factors regulate stroke volume?
Preload, afterload, and contractility
What is preload?
Amount of stretching of ventricular myocytes prior to contraction, determined by amount of blood filling the ventricle
When preload increases, the force of contraction _______________
Increases
Therefore increased preload —> increased stroke volume
What is afterload??
Tension acting on ventricular myocytes after the onsite of myocyte shortening, determined by the degree of arterial tone
T/F: when afterload increases, stroke volume increases
False
When afterload increases, stroke volume decrease
What in inotropy?
Inherent ability of cardiomyocyte to contract
One of the primary way the body comespates for decreased CO is making and pumping more blood. How does this contribute to worsening cardiac dysfunction?
More blood —> larger EDV —> increased SV —> increased CO
Increased afterload to overcome —> more back up in heart —> more congestion
What are the acute responses to decreased cardiac output?
Decreased stretch in baroreceptors —> increase SNS
—> INCREASE HR
—> VASOCONSTRICTION
—> INCREASE CONTRACTILITY
What is the chronic response to decreased cardiac output?
Decreased renal blood flow—> RAAS activation
T/F: chronically activation of angiotensin II can worsen heart fialure
True
—> increased vasoconstriction and increased water retention and stroke vol
Increased afterload and increased preload —> more congestion
What are two ways the heart can change in response to hemodynamic overload?
Concentric hypertrophy -> thickened muscle wall
-in response to pressure overload
Eccentric hypertrophy -> stretching
-in response to volume overload
As heart disease worsens, hydrostatic pressure in the pulmonary and/or systemic system continues to rise and eventually fluid in intersitial space overcomes lymphatic causing what type of heart failure?
Congestive
If ventricular contractility is markedly depressed, cardiac output will be too low to maintain adequate tissue perfusion and arterial BP may also fall causing what type of heart failure?
Low output heart failure
What type of heart failure is more common and why?
Congestive heart failure more common because body prioritizes maintenance of normal arterial pressure over maintenance of normal venous pressure
What are the 6 mechanisms of heart failure?
- Myocardial systolic dysfunction
- Myocardial diastolic dysfunction
- Volume overload
- Pressure overload
- High output states
- Rhythm disturbances
CAT
Tachypnea
Dyspnea
Lethargy
Syncope
What type of HF is this?
Congestive Heart failure
These signs are consistent with left or right CHF
- Dyspnea is more pronounced in left
- Abdominal distention would be seen in right
DOG
Tachypnea Cough Dyspnea Exercise intolerance Syncope
What type of heart failure is this?
Congestive
Signs could be due to left or right.. this is likely left because there is no abdominal distention
DOG
Exercise intolerance Weakness or collapse Lethargy Depressed mentation Pallor Hypothermia
What type of heart failure is this?
Low output heart failure
-signs in the cat would be similar
What are the three main goals of heart failure therapy?
Relieve congestion
Improve cardiac output
Prevent progression (cardioprotection)
How can congestion be relieved when treating heart failure?
Decreased ventricular filling
- decreased blood volume (preload) —> diuretics/dietary sodium restriction/venodilators
- increase forward flow
Abdominocentesis/throacocentesis
How can you improve cardiac output in systolic dysfunction?
Increase ventricular contractility—> positive inotropic drugs
Decrease afterload —> arteriodilators
How can you improve cardiac output for diastolic dysfunction?
Need to improve ventricular relaxation and decrease heart rate
T/F: sinus tachycardia is a compensatory mechanism in HR to improve cardiac output
True
What is the consequence to a pathological tachyarrhythmia during heart failure?
Heart rate is too high —> diastole time is too short —> EDV falls —> SV falls —> CO falls
What is the consequence of pathological bradyarrhythmia during heart failure?
HR too low —> ventricles are to ejecting blood into arteries frequently enough to maintain BP and meet body’s metabolic requirements
What are the classes of cardiovascular drugs?
Diuretic ACE inhibitors Vasodilator Positive inotropes Anti-arrhythmics Cardioprotective
What is the first choice drug for CHF and what is its MOA?
Furosemide
Inhibit Na/K/Cl cotransporter in thick ascending loop of Henle —> increase Na, K, Cl, Mg, Ca, H, NH4+, and HCO3- secretion —> water secretion
How can you administer Furosemide?
Oral
IV
IM
SC (off label)
What is the dose for acute/emergency CHF of furosemide ?
Dog: 2-4mg/kg IV or IM +/- CRI
Cat: 1-3mg/kg IV or IM +/- CRI
What are the the expected/adverse effects of furosemide and hydrochlorothiazide?
Expected: polyuria and polydipsia
Adverse:
- volume depletion and pre-renal azotemia
- electrolyte imbalances
- renal failure
- ototoxicity
- dermal ulcerations
What drug has better bioavailability and longer duration than furosemide, often used as an adjunct therapy in refractory CHF?
Torsemide
What is the MOA of hydrochlorothiazide?
Inhibits Na/Cl cotransporter in the distal tubule, which results in incresed renal excretion of sodium, chloride, and water
-also increase K, Mg, and phosphate
What is the potassium sparing diretic?
Spironolactone
What is the MOA of spironolactone?
Aldosterone receptor antagonist
Why use spironolactone in CHF patients?
As add on to furosemide in patients that are becoming hypokalemic (potassium sparing)
Cardioprotective (anti-fibrotic effects)
What are the ACE inhibitor drugs?
Benazepril
Enalapril
What is the MOA of enalapril and benazepril?
ACE inhibitors
-inhibit conversion of angiotensin I to angiotensin II
What are the uses of ACE inhibitors in heart failure?
Inhibit chronic effects of RAAS—> decreased afterload due to vasodilation
Cardioprotective by helping to prevent myocardial fibrosis
What are adverse effects of ACE inhibitors?
Systemic hypotension
Impaired renal function
GI upset
When is use of ACE inhibitors contraindicated?
Dehydrated or hypotensive patients
Caution in renal disease and with concurrent NSAID use —> decreased perfusion pressures and low GFR
What is the MOA of nitroglycerin and nitroprusside ?
Increase production of nitric oxide -> vasodilation
T/F: nitroglycerin and nitroprusside are given topically, usually on the inner surface of pinna
False
Only nitroglycerin is given topically
Nitroprusside is a potent and rapid arterio-and vasodilator —> is CRI and must be closely monitored
Nitroglycerin is primarily a arterio- or venodilator?
Venodilator (reduce preload)
What is the MOA of hydralazine ?
Potent arteriodilator
Interferes with cellular calcium metabolism in smooth muscle
What is the indication for hydralazine?
For severe/life-threatening pulmonary edema if nitroprusside is not an option
Oral
What is the MOA amlodipine?
Arteriodilator
Calcium channel blocker
What is the main use of amlodipine?
Chronic treatment of systemic hypertension (cats and dogs)
Adjunct therapy in refractory CHF
What is the MOA of sildenafil?
Pulmonary arteriodilator
Inhibit phosphodiesterase 5
What is the main use of sildenafil?
Moderate to severe pulmonary hypertestion
What is the MOA of pimobendan?
“Inodilator”
Calcium sensitization —> increase contractility
phosphodiesterase 3 inhibitor —> vasodilator
What is the main use of pimobendan ?
Canine HF due to degenerative valve disease/ dilated cardiomyopathy
Inodilator
What is the MOA of dobutamine ?
B1 agonsit
—> inotropic
When do you use dobutamine?
Severe HR and cardiogenic shock
-when there is lack of response to other drugs
What is the MOA of diltiazem?
Class IV
Calcium channel blocker
What are the uses of diltiazem ?
Atrial fibrillation
Supraventricular tachycardia (SVT)
Can be used to improve myocardial relaxation in hypertrophic cardiomyopathy
What is the acute (emergency) dose of diltiazem ?
0.1mg/kg IV slow over 5mins
What drug slows conduction through the AV node and is used in conjunction to diltiazem to control heart rate in AF and SVT ?
Digoxin -cardiac glycoside
What is the MOA of lidocaine?
Class I
Sodium channel blocker
What is the main used of lidocaine IV?
Suppress VPC and ventricular tachycardia
What is the actue(emergency) dose of lidocaine?
Dog: 2mg/kg IV slow over 2-3mins
Cat: 0.2mg/kg IV slow
What is used for chronic management of ventricular tachycardia?
Mexiletine (PO)
Class I sodium channel blocker
What is the MOA of sotalol?
Class III potassium channel blocker
Beta blocking effects
-typically used for chronic management of ventricular tachycardia and other complex ventricular ectopic
What is the MOA of amiodarone ?
Class III potassium channel blockers
What are the uses of amiodarone?
Post cardioversion of AF
Refractory ventricular tachycardia
What are the cardioprotective drugs?
Beta blockers
ACE inhibitor
Aldosterone antagonist
What does chronic sympathetic stimulation do to cardiac muscle?
Fibrosis
Apoptosis
Necrosis
When are beta blockers contraindicated
Acute heart failure
Use cautiously in patients with ventricular systolic dysfunction
What non pharmacologic methods can you use in treatment of heart failure?
Supplemental oxygen
Thoracocentesis /abdominocenesis
Mechanical ventilation
What diets should you recommend to patients in heart failure?
Complete and balanced with high quality protein and moderate sodium restriction is possible
What is the cause of cardiac cachexia?
Loss of lean body mass
- increased inflammatory cytokines
- decreased appetite/intake
—> omega fatty acids are beneficial —>inflammatory
T/F: mild azotemia is relatively common in patients with CHF
True
-often pre renal -> from diuretic or decreased CO
Mild elevations in BUN/CREA do not warrant a reduction in diuretic dose
CHF is a chronic condition that usually progresses to death, what is the exception to this?
If the underlying disease is reversible, CHF will resolve
