Cardiac Failure   and theTherapeutics of   Failure   Rebecca E.   Gompf
Normal Heart Function Maintain blood pressure Perfuse lung and tissues Maintain normal venous pressure Maintain system...
Abnormal Heart        Function Low blood pressure Decreased tissue perfusion Increased venous pressures Increased capi...
Factors of Cardiac      Performance Cardiac output = heart rate X  stroke volume Stroke volume = end diastolic  volume-e...
Stroke VolumeSV = contractility X preload             afterloadSince CO = HR X SV        ThenCO = heart rate X contractili...
Preload Force that stretches ventricular  fibers Increases contractility at first Increases stroke volume Estimated as...
Afterload Impedes ventricular contraction  and ejection of blood Due to vascular resistance Increases ventricular wall ...
Contractility Sarcomere contraction Many factors affect it—cardiac  and systemic factors Increased contractility increa...
Compliance Pliability of the ventricles so that  they can fill. Influenced by wall thickness Also influenced by pericar...
Heart Rate Influenced by many factors Increased heart rate will increase  cardiac output up to a point Decreased heart ...
Synergy Coordinated function of the atria  and ventricles to optimize heart  function Arrhythmias disrupt synergy and  d...
Heart Disease Abnormal heart Heart may or may not be in  failure Congenital Acquired 10% of dogs have heart disease
Circulatory Failure Insufficient cardiac output of any  cause One cause is heart failure
Heart Failure Heart cannot pump blood  presented to it-congestive Or heart cannot meet body’s  needs- output failure
Heart Failure Venous overload results in  congestion Inadequate perfusion
Heart Failure Normal heart=low diastolic size  and low venous pressure Failing heart=high diastolic size  and high venou...
Heart Failure   Congestive failure--edema,    effusions   Low output failure
Heart failure Clinical syndrome Not a specific disease!
Left sided Congestive        Heart Failure Left sided congestive heart failure  (CHF) Cascade of events that starts  wit...
Left sided congestive heart          failure Increased LV diastolic pressure Increased LA diastolic pressure Increased ...
Left sided congestive        heart failure Increased pulmonary capillary  hydrostatic pressure Fluid into interstitial a...
Causes of increased LV      diastolic pressure Increased preload Decreased compliance Increased afterload Combinations...
Right sided congestive        heart failure Increased right ventricular diastolic  pressures Increased right atrial dias...
Right sided Congestive    Heart Failure Increased systemic capillary bed  pressure Edema (pleural effusion, ascites)
Causes of Right Sided            CHF Increased preload Decreased compliance Increased afterload Combination of above
Biventricular Heart          FailureBoth sides of the heart fail
Low output failure Either right or left side cannot  pump enough blood to perfuse  tissues Dilated cardiomyopathy (end  ...
Causes of Heart Failure Pressure overload Volume overload Pump failure
Causes of Heart Failure Arrhythmias Myocardial restriction High output states
Pressure Overload Excessive afterload diastolic dysfunction Contractility ok Examples: subaorticstenosis,  pulmonicste...
Volume Overload Excessive preload Systolic dysfunction Contractility ok at first Examples: Mitral regurgitation,  pate...
Pump Failure Insufficient contractility Systolic dysfunction Low output failure Also, congestive failure
Pump Failure Dilated cardiomyopathy Ischemia/infarcts Chronic heart disease Dysenergy Drugs
Arrhythmias Changes in rate, rhythm, or  conduction Affects heart rate, synergy, and  ventricular filling Examples: tac...
Myocardial Restriction Interferes with ventricular filling Diastolic dysfunction Contractility ok Examples: hypertroph...
High output states Increased need for tissue blood  flow Heart is normal until later Examples: hyperthyroidism,  chroni...
Classes of Heart Failure Mild Moderate Severe Modified NYHA Classes
Compensatory        Mechanisms Sympathetic Nervous System RAAS system activation Myocardial remodeling
Sympathetic Nervous         System Heart rate increased due to  stimulation of Beta1 receptors on  SA and AV nodes Incre...
Sympathetic Nervous         System Increased contractility by  stimulation of Beta1 receptors  and epinephrine and  norep...
Sympathetic Nervous         System Causes peripheral arteriolar  vasoconstriction by stimulation of  Alpha1 receptors Pr...
RAAS System Increases preload to try to  increase cardiac output Activated by decreased renal  perfusion Renin released...
RAAS System Angiotension II is potent  vasoconstrictor which increases  afterload and preload Angiotension II has adrena...
RAAS System In early heart disease, can return  CO to normal In later heart disease, increases  preload which increases ...
RAAS System Antidiuretic hormone (ADH)  released by increased  angiotension II ADH causes renal retention of  fluid whic...
Myocardial Remodeling Chronic volume overload  increases diastolic stress Heart lays down more sarcomers  end to end Re...
Myocardial Remodeling Chronic pressure overloads Heart lays down more sarcomers  in parallel so that wall becomes  thick...
Side Effects of Remodeling Dilated ventricle eventually has  decreased contractility Excessively hypertrophied  ventricl...
Clinical Signs of Heart            Failure Decreased cardiac output  (exercise intolerance) Pulmonary congestion (coughi...
See notes on hormonesand cardiac failure p.96
Physical Exam Findings    with Left Heart Failure Possible murmur or gallop Tachycardias or bradycardias Coughing and/o...
Physical Exam Findingswith Left Heart Failure Pulmonary crackles (rales), not  always Prolonged capillary refill time =>...
Physical Exam Findings    with Right Heart Failure Systemic congestion (ascites in  dogs, pleural effusion in cats,  peri...
Cats with Left or Right        Heart Failure Dyspnea is primary sign** Cats may or may not cough with  left heart failur...
Therapy Goals Reduce congestion Increase cardiac output Decrease cardiac work load Control arrhythmias, heart rate Tr...
Therapy Goals Modify the neurohormonal  compensation Modify cardiac remodeling Improve the patient’s quality of  life ...
RAAS Beta blockers decrease renin  release ACE inhibitors interupt  conversion of AGI to AGII ARBs (angiotension recept...
Sympathetic Stimulation Beta blockers prevent stimulation  of heart by sympathetic system Alpha antagonists block alpha ...
Water retention Diuretics counteract it ACE inhibitors also counteract it
Cardiac Remodeling ACE inhibitors and aldosterone  antagonists Beta blockers Arteriolar dilators to reduce  afterload ...
Reduce Preload Diuretics ACE inhibitors Venodilators Low salt diet Do not reduce preload too  much!b/c these rely on ...
Afterload Reduction ACE inhibitors - dilate Arteriolar dilators Must treat other diseases causing  the increased afterl...
Increase Contractility Digoxin (wk. positive inotrope) Pimobendan (st. pos. inotrope) Catetcholamines IV Increases myo...
Increasing Compliance Calcium channel blockers may  relax heart Decrease heart rate so heart can  fill Remove pericardi...
Heart Rate Must treat tachycardias or  bradycardias Antiarrhythmic therapy if needed. Find and treat any underlying  sy...
Restore Synergy Treat significant arrhythmias with  appropriate drugs Treat heart blocks
Stabilize Patient Diuretics Cage rest Oxygen Venodilators Find and treat underlying problem
Positive Inotropes Digitalis Pimobendan (newest ones) Catecholamines (emergency) Others
Positive Inotropes Affect calcium in some manner Used only with systolic function  with decreased contractility Increas...
Positive Inotropes Do not cure disease!!*** Efficacy varies b/t patients Give symptomatic improvement  is the goal of Tx
Digitalis Increases contractility in normal  and failing hearts Only increases cardiac output in  failing hearts Weak p...
Digitalis Negative chronotrope Increases myocardial excitability Better for volume overloads and  myocardial disease. N...
Digoxin ECG Changes Seen mainly with toxicity Slower heart rate First degree heart block Mild ST changes (depression)...
Digitalis Digoxin Digitoxin Oral drugs Well absorbed but, absorption  decreased by food, drugs, and  malabsorption sta...
Digitalis Digoxin eliminated by kidneys Slow oral method of dosing Cats (sick) are more intolerant of  digoxin. Don’t u...
Digitoxicity Vomiting, diarrhea, anorexia Arrhythmias Negative inotrope Enhanced by hypokalemia, low  magnesium, hyper...
Digoxin Drug       Interactions Quinidine Aspirin (high levels) Amiodarone (same class w/  Sotalol) Spironolactone Ci...
Digoxin Crosses placenta Older dogs less tolerant of  digoxin Giants breeds need less Hypothyroid dogs have problems  ...
Digoxin Levels Run in human hospitals Low therapeutic index
Indications for Digoxin SVT (Supraventricular  tachycardia) or Hearts with decreased  contractility Does not prevent pr...
Contraindications for          Digoxin Ventricular arrhythmias (severe) Animals with just a murmur Pericardial disease...
Contraindications for          Digoxin AV blocks Hypertrophic cardiomyopathy Aortic stenosis Pulmonic stenosis Pulmon...
Pimobendan Inodilator = positive inotrope and  peripheral vasodilator Increases cardiac output Decreases preload and af...
Pimobendan Oral drug Well absorbed Out via feces Used in addition to other  medications (instead of digoxin)
Pimobendan No drug interactions But, it is a vasodilator so when  using other vasodilators, be  careful of hypotension....
Pimobendan Side Effects Uncommon – yea! Vomiting/diarrhea-uncommon Polyuria/polydipsia-uncomon Anorexia-uncommon Sinu...
Pimobendan Efficacy in cats being studied Does not stop the progression of  the disease process Can accelerate the prog...
Catecholamines Stimulates beta receptors and  cyclic AMP Synergistic with digoxin Metabolized in the liver (IV drugs)
Catecholamines    Contraindications Hypotension or hypertension Sinus tachycardia Arrhythmias Cardiac disease with mec...
Epinephrine Increases heart rate (thru beta  receptors) Increases blood pressure Increases cardiac output  (contractili...
Isoproterenol Increases contractility Increases heart rate Increases cardiac output Causes hypotension Used for heart...
Dopamine Increases contractility Increases heart rate (sinus  tachycardia) Increases blood pressure  (vasoconstricts) (...
Dopamine Side Effects Tachycardias--high doses Arrhythmias--high doses Hypotension--low doses Hypertension--high doses...
Dobutamine      Hydrochloride Increases contractility No vasodilatation or  vasoconstriction Cats can seizure or vomit...
Dopamine versus      Dobutamine Same price now Dobutamine does not induce  tachycardias or affect peripheral  vasculatur...
Amrinone Increases contractility Vasodilates Expensive
Diuretics To relieve excessive fluid  accumulation Decrease preload Relieve signs of failure only
Types of Diuretics Xanthine derivative Thiazides Aldosterone inhibitors Ethacrynic acid Loop diuretics—furosemide –  ...
Xanthines     Bronchodilators Weak diuretics Weak positive inotropes Dilates coronary, pulmonary ,  renal, and systemic...
Bronchodilators Aminophylline Theophylline
Bronchodilators Metabolized in the liver Side effects: vomiting, sinus  tachycardia, hyperexcitability  (MAY happen and ...
Thiazide Diuretics Effects are not dose dependent Not as potent as furosemide but  have a more sustained diuretic  effec...
Thiazides Side effects uncommon Cheap No drug tolerance develops Can be used with other diuretics Well tolerated Eff...
Thiazides Only disadvantage--only oral  form Drug interactions--penicillins
Aldosterone Inhibitors       Spironolactone Takes 2-3 days to be effective Weak diuretic Used in combination with other...
Furosemide Loop diuretic Effect is dose dependent Will dehydrate animal Comes in IV and oral forms Inexpensive
Furosemide Side effects--hypokalemia,  hyponatremia, dehydration,  prerenal azotemia Tolerance develops Drug interactio...
Vasodilators Arterial dilators Venodilators Mixed vasodilators
Arterial dilators Counteract reflex  vasoconstriction of heart failure Decreases work load of left  ventricle Improves ...
Venodilators Increase vascular capacity Decrease venous pressure (less  bld goes back to the heart) Decrease preload D...
Vasodilator Uses Chronic, congestive heart failure Valvular heart disease (leaky  valves) Congenital heart problems (PD...
Vasodilator    Contraindications Hypotension Coronary artery disease (some) Poor cardiac contractility Tachycardias
Vasodilator Net Effects Decreased preload Decreased afterload Increases cardiac output Decreased workload of heart An...
Hydralazine Pure Arterial dilator Uses--dogs with mitral  regurgitation, hypertension Side effects in 50%--hypotension,...
Nitrates Nitroglycerine ointment--  venodilator, no side effects,  topical Sodium nitroprusside--IV, mixed  vasodilator,...
Prazosin Arterial and venous dilator Metabolized in the liver Does not cause a reflex  tachycardia Unknown if animals ...
Angiotension    Converting Enzyme     Inhibitors (ACE) Captopril (not used much b/c had  many problems) Enalapril Benaz...
ACE Inhibitors Stop conversion of angiotensin I  to angiotensin II in lungs Decreases plasma aldosterone  levels Increa...
ACE Inhibitors Increases effects of thiazide  diuretics Causes retention of potassium Does not cross blood brain  barrier
ACE Inhibitors Used in: Dilated cardiomyopathy Mitral regurgitation Volume overloaded hearts  (shunts such as PDA, VSD)...
Enalapril Side effects uncommon--  hypotension Improves heart failure and  increases survival Takes 7-10 days to reach ...
Enalapril Hard to use in renal patients so  use benazepril Improves dog’s quality of life and  increases longevity Use ...
Beta Blockers’ Actions Decrease contractility (negative  inotrope) Decrease heart rate Decreases myocardial oxygen  con...
Beta Blockers Used to slow AV conduction and  slow heart rate with SVT Also used in hypertrophic  cardiomyopathy
Beta Blockers Propranolol Atenolol Metroprol Carvedilol Other ―–ol‖ drugs
Beta Blockers Side Effects Blocking beta 1 receptors in heart  will decrease contractility and  heart rate Blocking beta...
Carvedilol Blocks beta 1 and beta 2  receptors Extends life span in people May help in dogs—studies  ongoing
All Beta Blockers Start at low dose and increase  gradually Do not stop abruptly Don’t start until heart failure  under...
Additional Therapy Cage rest Low sodium diet Narcotics Removing accumulated fluids
Acute Pulmonary Edema Diuretics Cage rest with oxygen Nitrol ointment ACE inhibitors Hydralazine or nitroprusside Ca...
Pleural Effusion Thoracentesis—but do NOT  stress Cage rest and diuretics
Chronic CHF Therapy Diuretics Venodilators—ACE inhibitors Treat the underlying heart  disease with appropriate drugs B...
Pressure Overload Excessive afterload Systolic dysfunction Subaortic stenosis or pulmonic  stenosis Pulmonary hyperten...
Volume Overload Excessive preload Systolic dysfunction Mitral or tricuspid regurgitation Shunts--PDA, VSD
Pump Failure Systolic dysfunction Cardiomyopathies--dilated,  myocarditis Chronic heart disease Dysynergy Drugs
Arrhythmias Changes in rate, rhythm, or  conduction Affects heart rate, synergy and  filling of the ventricles Effect d...
Myocardial Restriction Diastolic dysfunction Restrictive cardiomyopathy Pericardial disease Tumors infiltrating myocar...
High Output States Excessive tissue demands Shunts Anemia Fever Hyperthyroidism
Cardiac Preformance Preload Afterload Contractility
Cardiac Performance Distensibility Heart rate Synergy
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
Tag training version 1.0
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  • Aka Diastolic dysfunction
  • Increase in HR will increase CO put to a certain ptHR of over 200 will decrease the amount of time the heart has to fill thus CO will decreaseVentricle has time to fill and fill and fill and fill (great prelload and contractility ) but b/c HR is so low
  • 70-80% filling is tolerated in a healthy heart but not so in a dz heartArrhythmias disrupt synergyA fib so no atrial contraction so atrial doesn’t contribute to filling so blood pools in atriaAsk L about VPC’s and synergy
  • Not as many cats have heart dz
  • When heart can not get enough blood to the rest of the bodyEx. hyperthyroid causes the bodies demands to be more b/c of increase in metabolism and the heart can’t get enough blood the body
  • Congestive heart failure when one part of heart doesn’t work and one of the chambers gets back up (left heart failure = fluid in lungs)
  • L ventricle failure blood accumulates in the Left ventricle and thus pulonary edemaRight geartfailre results in build of blood in the venous system all over the body (ascities)
  • Diastolic size is the size of the heart during diastole
  • L sided heart failure is main cause of increased hydrostatic pressure => pulmonary edema
  • Ex. too much fluids (increased preload)Valvulardz is the most common cardiac cause of increased LV DP d/t increased preloadLook at notes p. 89 to see examples of both
  • Left sides heart failure is the same signs in all sppRight sides is different in spp see p. 89
  • See p.89
  • Very little left sided signs and the signs of right sided CHF are the ones that persist and you will see
  • This can be from either side of heart failing, it is not specific for one sided CHFBodies tissue aren’t perfused well so can result in syncope if not enough to brain, also exercise intolerance
  • The Lventricle not working wellPressure overload cause hypertrophy in the heart and thus decreases size of the lumen of the LVSubaorticstenosis increases restriction to flow out of the LV and LV hypertrophies and has to push harder to get it out thus the pressure of blood coming out will be greater
  • Diastolicdysfxn – pressure overload
  • 75% of dogs with heart dz have thisDilitation is the first response of the heart to vol overload but at some point the fibers strecth too much and the then loses contractility
  • From aorta to the pulmonary artery -PDA
  • Basic problem with heart Vol overload can eventually cause thisBut as primary dz it is caused by DCM
  • Dogs die of arrhythmias and heart failure – not heart attacksArrhythmias can eventually lead to pump failure if they are fast enough and for long enough
  • Tachy 2.5 times normal HR is badBrady don’t usually lead to congestion, tachy can
  • These are normal P QRS TThis is a tach. If it keeps going it can lead to cardiomyopathy
  • HCM in fel
  • HCM in fel (this LV)Lumen spaces decreases and leads to congestion of left atrium
  • Heart is small b/c of fluid in pericardial sac that keeps the ventricle from filling -> diastolic dysfxn
  • Most common cause is hyperthyroidism
  • NE and E sensitize the heart to arrhythmiasThe longer the SNS acts we get blunting and the SNS doesn’t work as well (analogy whipping a dying horse) can make things worse
  • You increase HR a certain point will increase COIf HR is 2.5 times normal for that animal then will have less time for filling and thus decrease cOSNS is not specificIncrease preload the increase stretch of the myocardial fibers and increases contractility and thus CO
  • This system kicks in when there is less CO esp to the kidneys so that they get more blood in the short run it works weel but tin the long term it increases the preload
  • Angi II constrictsarterieas and veins (most potent vasoconstrictor in the bodyIn a failing heart it will increase the workload to the heart and that is not good -> congestion
  • If volume overload (mitral vlaveregurg most common) then increase diastolic stress and dilatation and that causes the heart to lay down more sarcomers (compensatory hypertrophy). Dilates first and then hypertrophy. Acute volume overload makes the heart wall (left ventricle) thin. Re,olded heart keeps CO up which makes the body happy but the heart is not happy.
  • Chronic hypertension – left ventricle has to generate increases force to keep blood in circulation and the heart compensates by laying down more sacomersamd so the heart get thicker and after a while hyperthrophy and thus the lumen decreases and the amoung of blood that can go in there decrease. = concentric hypertrophyDilaitation is immediate but hyperthrophy takes time.
  • The heart can return to normal overtime but depends on how long it has been going on and how bad it is
  • Gallop is S3 or S4 when it shouldn’t be thereS3 = big ventriclesS4 = big atriumsNot every dog with heart dz has a murmur esp with DCMIncreased HR and arrhythmias can mask murmursDog in heart failure should be tachyBrady will happen right at the end (near death) and may occur with blocks
  • Just b/c the lungs sound clear does not R/O heart refillVolume overload can also cause weak femoral pulses
  • Don’t lie down until they are exhausted or the heart failure is getting under control
  • When they lie down that is a good sign
  • There are species differences with these findingsVolume backs up in liver and thus ascites = DOGSVessels in the pleural space effected and thus pleural effusion = CATS
  • Looks thin from up above and ascites
  • Can eventually get ventral edema when abd and chest get full. This is rare though
  • Result of right sided heart failure
  • When get fluid in lungs get dyspnea (may or may not cough)
  • Severe HCM with severe pleural effusion
  • Get blue but that is a very late change
  • p. 101 in notes
  • In human med they go for quantity of life and in vet med we go for qualityThesedz don’t cause pain in our patients
  • Does not work in the lungs and does not decrease pulmonary hypertensionIt takes time for the ACEi to work (7-10 days to see effects)By interrupting AGII you reduce effectiveness of aldosterone so you decrease fluid buildup - > goodACEi used a lot in vet med but do not stop the progression of the dzARB’s are used in human med in people can’t use ACEi – these aren’t used in vet med yetSpironolactone – wk diuretic (aldosterone antagonists). Aldosterone effects cardiac remoldling so these drugs help to prevent remolding
  • People with CHF do better on beta blockers but this is not proven in animals yet but very close to knowing if that is true in animals. Beta blockers have the potential but they aren’t used yet.Beta blockers used for HR controllers but not for longevity in CHF. These are neginotropes so that is why we don’t use in CHF.
  • These drugs halt the remoldling but they don’t reverse the dz
  • Diuretics reduce the amount to fluid retained by the bodyACE I vasodilateLow salt diet do play a role but don’t start dog with a murmur and no dz on low salt diet b/c it will not be beneficial
  • Ventricle cannot fill with decreased compliance (relaxation). Compliance is not a passive process, it takes energy.This is hard to measure/evaluate.If we have problems with compliance it is with diastole
  • AbnormVPC’s if they come from place in heart that makes heart contract from base to apex then CO is decreased greatly
  • Left sided heart failure – diuretics (lasix) and cage rest is the main stay of TxRight sided heart failure – have to remove the fluid first then Lasix and cage rest
  • In early mitregurg in sm dogs no contractility problem, but may eventually effect contractility
  • Not well understood how dig effects Ca and how the heart usesPimobindin induces arrhythmias in humans, so only used in vet med
  • We are treating symptoms to make the animal more comfortable, they are not a cureDCM – taurine deficit in cats causes it
  • DigoxinIn human med it doesn’t exend life but makes it better, so goes in and out of favorDig is cheap and Pimobendin is expensiveDecreases HR – negchronotrope- slows S stimulation, slows conduction thru AV nodeUse to slow HR in a fib in dilated dog
  • SA nodal conduction slowed-prolongs APDecreases pol in atriums and ventricles (myocardial tissue) – shortens APThe effect is opposite in myocardial tissue and AV node.
  • Give orally and no need for loading dose
  • At toxic dose can become neginotropeLasix can cause hypoK+, be aware of it and use can use Dig with Lasix. The reason Dig and Lasix together is contraindicated is b/cLasix can cause hypoK+. There is not drug interaction.
  • Quinidine increased HR at first I horse before it converts the horse, so may use Dig first to slow HR.She uses Spironolactone and not seen any problems clinically
  • She has no experience with this. Never treated preg animal with heart failure.Dig dosed on lean body weightLose lower dose in older animals b/c of decreased renal fxnHypothyroid effects distribution of Dig in body an dthus uncontrolled hypothyroid can lead o Dig toxicity
  • 0.01 mg/kgDose is lowCheck dose several times before givingCan run dig levels on blood. Very easy to get to toxic levels.If at therapuetic level and still need more then add a combo drug.
  • Animals with just murmurs don’t need to be treated they need to a heart workup to see how severe their heart dzPericardial dz is problem with fluid around heart so the heart can’t fill and dig will not help with this. Contractility is not a problem.Cardiomyopathy has no contractility problem so dig won’t help
  • Increased pressure and heart working fine then dig will not work,b/c contractility is fine – pulmonary or systemic hypertension
  • Is not diuretic and not a brochodilator
  • Don’t have to worry about liver or kidneydz when giving this drug
  • Can be used with brochdilators (collasped tracheas) Can be used with ACE I but watch for hypotension
  • Use in DCM with catsPDA puppy sent home on Pimobendanb/c volume overload is so bad and thus anesth risk
  • Increase contractility
  • Catechol stimulate beta receptors
  • IV drugHypoxic heart will be sensitized to arrhythmias if you use epinephrineUse this drug in CPR
  • Use mainly to increase HR in complete heart block dogsUse during anesth when putting in pacemaker, to keep heart rate up while putting pacemaker
  • Vasodilates at low levels but to increase contractility you have to use higher doses which vasoconstricts which is not good for kidneysPositiveinotrope
  • Don’t use in right heart failure b/c of the above last point
  • Does not stimulate beta receptors More expensive than Dop or Dob
  • Removes signs of failures/congestion – the only drug that will do this
  • Used more for bronchodilitation than for diuret
  • Used to think that side effects were uncommon but now they are giving dogs renal failure, there have been not studies done with these drugs. Only info we have is from human med. Caution with use b/c no good studies. Check lytes and if they are off then stop use of the thiazides. If there is a dog that is refractive to diuretics then might try thiazides. Don’t use with penicilans
  • Can’t be used alone as a diureticIn right sided heart patients can’t get rid of the acsitesw/ Lasix alone, need to add spironolactone to LasixStops and reverses cardiac remolding with chronic congestive heart failure in humans – don’t know if this is true in animals. Adding spironolactone will no hurt the dog.Don’t use without Lasix.With left sided heart failure she will use this but not from the beginning, she will add it in later. But with right sided heart dogs she will start with Lasix and spironolactone.This drug spares K+ and so do ACEi. If you use them together then keep an eye on K+, esp if animal has compromised renal fxn. Lasix is K+ wasting, so if on Lasix, spironolactone and ACEi then probably not a problem.
  • Back bone of Tx for congestive heart failureCan give IM or SQ, if animal is stressedUse with left sided heart failure
  • Few doses of Lasix, fluids and food and they will be fineMonitor renal fxn and lytes when an animal is on a diurecticOnly use Lasix when the animal is in heart failure, not beforeAminoglycosides – Lasixconc this Abx in the kidneys and thus toxicity is reached more quickly. This Abx isn’t used much any more but just be aware of this.Pachake insert says otic toxicity but she hes never observed this.Lasix and Dig can be used together even though it says not to. Remember that when K+ is low that Dig can be toxic and Lasix is K+ wasting. But you wil be monitoring K+ so ok.
  • Pulmonic, aortic stenosis, HCM = don’t use with these (pressure overload)these can cause hypotensionUse with volume overload
  • Most of these drugs don’t work the same in pulmonary circulationVasodilation will not happen in the pulmonary circulationVasodilation is systemicLeft atrium is low pressure and aorta is high pressure. If sytemic pressure is decreases then more flow to aorta
  • Lessbld to right ventricle -> less blood to the lungsMixed vasodilator will cause less side effects
  • Can use Viagra for pulmonary hypertensionSystemic hypertension – increased afterload is not good to hypertensive animals. Ca channel blocker (Amlodipine) works great in hypertensive cats.
  • Hypotension is the only case in vet med where vasodiltor is contraindicated
  • Used in emergenciesith mitral valve regurg and failing heartKnow side effects and that it is a pure arterial dilator – she didn’t spend much time on this
  • Na + nitroprussisdeNext drug of choice for dog that is not responding to LasixImportant that this be given at appropriate dose over the correct rate – Need to use a fluid pumpRescue drug for left sided heart failure if not responding to LasixNytroglycerine ointment for left sided heart failure with no side efects, but no studies done
  • Not used much, spend 30 sec on this one
  • Side effect : hypotension -> renal failureIf use drugs off label when there are other drugs that are used in vet medIf you can find a dose in the lit then you can use it off label safely
  • Not an acute drugIt will take 7-14 days to have max effectsDCM, mitral regurg dogs life better life with ACEi – it doesn’t stop the progression
  • Use with Volume overload, advanced heart dz, regurg dogs
  • Didn’t talk about this
  • If left sided heart failure then diuretics and cage rest (O2 is nice)If right sided then drain fluid, diuretics and cage restVasodilators (Na+ nitroprusside) the next drug in LSHF if not responding to Lasix. Monitor respriatory rate and effort. If RR decreases then you are making progress in treating to Tx.
  • Tag training version 1.0

    1. 1. Cardiac Failure and theTherapeutics of Failure Rebecca E. Gompf
    2. 2. Normal Heart Function Maintain blood pressure Perfuse lung and tissues Maintain normal venous pressure Maintain systemic and pulmonary capillary pressures
    3. 3. Abnormal Heart Function Low blood pressure Decreased tissue perfusion Increased venous pressures Increased capillary pressures
    4. 4. Factors of Cardiac Performance Cardiac output = heart rate X stroke volume Stroke volume = end diastolic volume-end systolic volume
    5. 5. Stroke VolumeSV = contractility X preload afterloadSince CO = HR X SV ThenCO = heart rate X contractility X PL afterload
    6. 6. Preload Force that stretches ventricular fibers Increases contractility at first Increases stroke volume Estimated as end diastolic volume
    7. 7. Afterload Impedes ventricular contraction and ejection of blood Due to vascular resistance Increases ventricular wall stress Increases work load of heart Decreases stroke volume
    8. 8. Contractility Sarcomere contraction Many factors affect it—cardiac and systemic factors Increased contractility increases stroke volume and vice versa
    9. 9. Compliance Pliability of the ventricles so that they can fill. Influenced by wall thickness Also influenced by pericardial diseases
    10. 10. Heart Rate Influenced by many factors Increased heart rate will increase cardiac output up to a point Decreased heart rates can decrease cardiac output
    11. 11. Synergy Coordinated function of the atria and ventricles to optimize heart function Arrhythmias disrupt synergy and decrease cardiac output
    12. 12. Heart Disease Abnormal heart Heart may or may not be in failure Congenital Acquired 10% of dogs have heart disease
    13. 13. Circulatory Failure Insufficient cardiac output of any cause One cause is heart failure
    14. 14. Heart Failure Heart cannot pump blood presented to it-congestive Or heart cannot meet body’s needs- output failure
    15. 15. Heart Failure Venous overload results in congestion Inadequate perfusion
    16. 16. Heart Failure Normal heart=low diastolic size and low venous pressure Failing heart=high diastolic size and high venous pressure Failing heart=cardiac reserve is used at rest
    17. 17. Heart Failure Congestive failure--edema, effusions Low output failure
    18. 18. Heart failure Clinical syndrome Not a specific disease!
    19. 19. Left sided Congestive Heart Failure Left sided congestive heart failure (CHF) Cascade of events that starts with increased left ventricular diastolic pressure
    20. 20. Left sided congestive heart failure Increased LV diastolic pressure Increased LA diastolic pressure Increased pulmonary venous pressure
    21. 21. Left sided congestive heart failure Increased pulmonary capillary hydrostatic pressure Fluid into interstitial and alveolar areas Pulmonary edema
    22. 22. Causes of increased LV diastolic pressure Increased preload Decreased compliance Increased afterload Combinations of the above
    23. 23. Right sided congestive heart failure Increased right ventricular diastolic pressures Increased right atrial diastolic pressure Increased central venous pressure
    24. 24. Right sided Congestive Heart Failure Increased systemic capillary bed pressure Edema (pleural effusion, ascites)
    25. 25. Causes of Right Sided CHF Increased preload Decreased compliance Increased afterload Combination of above
    26. 26. Biventricular Heart FailureBoth sides of the heart fail
    27. 27. Low output failure Either right or left side cannot pump enough blood to perfuse tissues Dilated cardiomyopathy (end stage)
    28. 28. Causes of Heart Failure Pressure overload Volume overload Pump failure
    29. 29. Causes of Heart Failure Arrhythmias Myocardial restriction High output states
    30. 30. Pressure Overload Excessive afterload diastolic dysfunction Contractility ok Examples: subaorticstenosis, pulmonicstenosis, hypertension
    31. 31. Volume Overload Excessive preload Systolic dysfunction Contractility ok at first Examples: Mitral regurgitation, patent ductus arteriosus
    32. 32. Pump Failure Insufficient contractility Systolic dysfunction Low output failure Also, congestive failure
    33. 33. Pump Failure Dilated cardiomyopathy Ischemia/infarcts Chronic heart disease Dysenergy Drugs
    34. 34. Arrhythmias Changes in rate, rhythm, or conduction Affects heart rate, synergy, and ventricular filling Examples: tachycardias, bradycardias, heart blocks
    35. 35. Myocardial Restriction Interferes with ventricular filling Diastolic dysfunction Contractility ok Examples: hypertrophic cardiomyopathy, pericardial effusion
    36. 36. High output states Increased need for tissue blood flow Heart is normal until later Examples: hyperthyroidism, chronic anemia, chronic fever
    37. 37. Classes of Heart Failure Mild Moderate Severe Modified NYHA Classes
    38. 38. Compensatory Mechanisms Sympathetic Nervous System RAAS system activation Myocardial remodeling
    39. 39. Sympathetic Nervous System Heart rate increased due to stimulation of Beta1 receptors on SA and AV nodes Increases cardiac output at up to 2 ½ times normal rate
    40. 40. Sympathetic Nervous System Increased contractility by stimulation of Beta1 receptors and epinephrine and norepinephrine Effects blunted in chronic disease and can make things worse
    41. 41. Sympathetic Nervous System Causes peripheral arteriolar vasoconstriction by stimulation of Alpha1 receptors Prevents hypotension Creates increased afterload and increased workload on the heart
    42. 42. RAAS System Increases preload to try to increase cardiac output Activated by decreased renal perfusion Renin released, converted to angiotension I converted to angiotension II by ACE
    43. 43. RAAS System Angiotension II is potent vasoconstrictor which increases afterload and preload Angiotension II has adrenals release aldosterone so that sodium and water retained which also increases preload
    44. 44. RAAS System In early heart disease, can return CO to normal In later heart disease, increases preload which increases cardiac work load and increases failure
    45. 45. RAAS System Antidiuretic hormone (ADH) released by increased angiotension II ADH causes renal retention of fluid which increases preload
    46. 46. Myocardial Remodeling Chronic volume overload increases diastolic stress Heart lays down more sarcomers end to end Result is dilation of the heart and eventually some hypertrophy (eccentric hypertrophy)
    47. 47. Myocardial Remodeling Chronic pressure overloads Heart lays down more sarcomers in parallel so that wall becomes thicker Concentric hypertrophy
    48. 48. Side Effects of Remodeling Dilated ventricle eventually has decreased contractility Excessively hypertrophied ventricle results in decreased lumen size, stiff ventricle, and decreased coronary artery filling
    49. 49. Clinical Signs of Heart Failure Decreased cardiac output (exercise intolerance) Pulmonary congestion (coughing, dyspnea)
    50. 50. See notes on hormonesand cardiac failure p.96
    51. 51. Physical Exam Findings with Left Heart Failure Possible murmur or gallop Tachycardias or bradycardias Coughing and/or dyspnea are the main 2 signs
    52. 52. Physical Exam Findingswith Left Heart Failure Pulmonary crackles (rales), not always Prolonged capillary refill time => decrease CO Weak femoral pulses (not always)
    53. 53. Physical Exam Findings with Right Heart Failure Systemic congestion (ascites in dogs, pleural effusion in cats, peripheral edema in horses, cows) Hepatomegaly, splenomegaly Distended jugular veins Cardiac cachexia
    54. 54. Cats with Left or Right Heart Failure Dyspnea is primary sign** Cats may or may not cough with left heart failure (usually not detected)
    55. 55. Therapy Goals Reduce congestion Increase cardiac output Decrease cardiac work load Control arrhythmias, heart rate Treat cause of heart failure
    56. 56. Therapy Goals Modify the neurohormonal compensation Modify cardiac remodeling Improve the patient’s quality of life Increase patient’s longevity
    57. 57. RAAS Beta blockers decrease renin release ACE inhibitors interupt conversion of AGI to AGII ARBs (angiotension receptor blockers) Aldosterone antagonists
    58. 58. Sympathetic Stimulation Beta blockers prevent stimulation of heart by sympathetic system Alpha antagonists block alpha one receptors in arterioles (over 50% dogs will get hypotensive). ACE I don’t cause hypotension.
    59. 59. Water retention Diuretics counteract it ACE inhibitors also counteract it
    60. 60. Cardiac Remodeling ACE inhibitors and aldosterone antagonists Beta blockers Arteriolar dilators to reduce afterload Reduce preload with ACE inhibitors and diuretics
    61. 61. Reduce Preload Diuretics ACE inhibitors Venodilators Low salt diet Do not reduce preload too much!b/c these rely on preload for CO
    62. 62. Afterload Reduction ACE inhibitors - dilate Arteriolar dilators Must treat other diseases causing the increased afterload. Hyperthyroid in cats Don’t overdo it as get hypotension.
    63. 63. Increase Contractility Digoxin (wk. positive inotrope) Pimobendan (st. pos. inotrope) Catetcholamines IV Increases myocardial oxygen demand and ATP consumption (down side) Find and treat underlying disease
    64. 64. Increasing Compliance Calcium channel blockers may relax heart Decrease heart rate so heart can fill Remove pericardial effusion. This is easy to do and rewarding. Find cause and treat
    65. 65. Heart Rate Must treat tachycardias or bradycardias Antiarrhythmic therapy if needed. Find and treat any underlying systemic problem contributing to the change in heart rate.
    66. 66. Restore Synergy Treat significant arrhythmias with appropriate drugs Treat heart blocks
    67. 67. Stabilize Patient Diuretics Cage rest Oxygen Venodilators Find and treat underlying problem
    68. 68. Positive Inotropes Digitalis Pimobendan (newest ones) Catecholamines (emergency) Others
    69. 69. Positive Inotropes Affect calcium in some manner Used only with systolic function with decreased contractility Increases oxygen and energy used by heart, so heart works harder Arrhythmogenic
    70. 70. Positive Inotropes Do not cure disease!!*** Efficacy varies b/t patients Give symptomatic improvement is the goal of Tx
    71. 71. Digitalis Increases contractility in normal and failing hearts Only increases cardiac output in failing hearts Weak positive inotrope
    72. 72. Digitalis Negative chronotrope Increases myocardial excitability Better for volume overloads and myocardial disease. Not good for pressure overloads.
    73. 73. Digoxin ECG Changes Seen mainly with toxicity Slower heart rate First degree heart block Mild ST changes (depression) Arrhythmias
    74. 74. Digitalis Digoxin Digitoxin Oral drugs Well absorbed but, absorption decreased by food, drugs, and malabsorption states
    75. 75. Digitalis Digoxin eliminated by kidneys Slow oral method of dosing Cats (sick) are more intolerant of digoxin. Don’t use it.
    76. 76. Digitoxicity Vomiting, diarrhea, anorexia Arrhythmias Negative inotrope Enhanced by hypokalemia, low magnesium, hypercalcemia, and alkalosis
    77. 77. Digoxin Drug Interactions Quinidine Aspirin (high levels) Amiodarone (same class w/ Sotalol) Spironolactone Cimetidine (decreases absorp of Dig) Verapamil
    78. 78. Digoxin Crosses placenta Older dogs less tolerant of digoxin Giants breeds need less Hypothyroid dogs have problems unless being treated
    79. 79. Digoxin Levels Run in human hospitals Low therapeutic index
    80. 80. Indications for Digoxin SVT (Supraventricular tachycardia) or Hearts with decreased contractility Does not prevent progression of the disease process
    81. 81. Contraindications for Digoxin Ventricular arrhythmias (severe) Animals with just a murmur Pericardial disease Restrictive cardiomyopathy Sinus node disease
    82. 82. Contraindications for Digoxin AV blocks Hypertrophic cardiomyopathy Aortic stenosis Pulmonic stenosis Pulmonary hypertension
    83. 83. Pimobendan Inodilator = positive inotrope and peripheral vasodilator Increases cardiac output Decreases preload and afterload Increases efficiency of cardiac cells
    84. 84. Pimobendan Oral drug Well absorbed Out via feces Used in addition to other medications (instead of digoxin)
    85. 85. Pimobendan No drug interactions But, it is a vasodilator so when using other vasodilators, be careful of hypotension. Negative inotropes may attenuate its positive inotropic effects
    86. 86. Pimobendan Side Effects Uncommon – yea! Vomiting/diarrhea-uncommon Polyuria/polydipsia-uncomon Anorexia-uncommon Sinus tachycardia at high doses Usually doesn’t worsen VPCs, but can cause them at high doses
    87. 87. Pimobendan Efficacy in cats being studied Does not stop the progression of the disease process Can accelerate the progression of mitral regurgitation (murmurs) if used too soon in the disease. Don’t start p on this drug if just has murmurs.
    88. 88. Catecholamines Stimulates beta receptors and cyclic AMP Synergistic with digoxin Metabolized in the liver (IV drugs)
    89. 89. Catecholamines Contraindications Hypotension or hypertension Sinus tachycardia Arrhythmias Cardiac disease with mechanical obstruction (aortic stenosis) With beta blockers
    90. 90. Epinephrine Increases heart rate (thru beta receptors) Increases blood pressure Increases cardiac output (contractility thru beat receptors) Increases arrhythmias Used mostly in CPR
    91. 91. Isoproterenol Increases contractility Increases heart rate Increases cardiac output Causes hypotension Used for heart block
    92. 92. Dopamine Increases contractility Increases heart rate (sinus tachycardia) Increases blood pressure (vasoconstricts) (dose dependent)
    93. 93. Dopamine Side Effects Tachycardias--high doses Arrhythmias--high doses Hypotension--low doses Hypertension--high doses (vasoconstriction) Increases pulmonary capillary pressure--high doses. Right heart to work against increased
    94. 94. Dobutamine Hydrochloride Increases contractility No vasodilatation or vasoconstriction Cats can seizure or vomit Dogs can vomit
    95. 95. Dopamine versus Dobutamine Same price now Dobutamine does not induce tachycardias or affect peripheral vasculature Both cannot be used more than 72 hours b.c they up regulate beta receptors and the receptors then become ineffective
    96. 96. Amrinone Increases contractility Vasodilates Expensive
    97. 97. Diuretics To relieve excessive fluid accumulation Decrease preload Relieve signs of failure only
    98. 98. Types of Diuretics Xanthine derivative Thiazides Aldosterone inhibitors Ethacrynic acid Loop diuretics—furosemide – used the most - Lasix
    99. 99. Xanthines Bronchodilators Weak diuretics Weak positive inotropes Dilates coronary, pulmonary , renal, and systemic arterioles and veins (v little effect) Bronchodilator
    100. 100. Bronchodilators Aminophylline Theophylline
    101. 101. Bronchodilators Metabolized in the liver Side effects: vomiting, sinus tachycardia, hyperexcitability (MAY happen and could last for 8 hrs.)
    102. 102. Thiazide Diuretics Effects are not dose dependent Not as potent as furosemide but have a more sustained diuretic effect New lipid soluable ones Not effective with compromised renal function
    103. 103. Thiazides Side effects uncommon Cheap No drug tolerance develops Can be used with other diuretics Well tolerated Effects aren’t dose related
    104. 104. Thiazides Only disadvantage--only oral form Drug interactions--penicillins
    105. 105. Aldosterone Inhibitors Spironolactone Takes 2-3 days to be effective Weak diuretic Used in combination with other diuretics Other benefits being explored Drug interactions—ACE inhibitors
    106. 106. Furosemide Loop diuretic Effect is dose dependent Will dehydrate animal Comes in IV and oral forms Inexpensive
    107. 107. Furosemide Side effects--hypokalemia, hyponatremia, dehydration, prerenal azotemia Tolerance develops Drug interactions--cephaloridine, polymixins, aminoglycosides
    108. 108. Vasodilators Arterial dilators Venodilators Mixed vasodilators
    109. 109. Arterial dilators Counteract reflex vasoconstriction of heart failure Decreases work load of left ventricle Improves tissue perfusion Decreases mitral regurgitation (indirectly) Side effect is hypotension
    110. 110. Venodilators Increase vascular capacity Decrease venous pressure (less bld goes back to the heart) Decrease preload Decreases pulmonary edema indirectly Side effect is decreased CO (be careful with this)
    111. 111. Vasodilator Uses Chronic, congestive heart failure Valvular heart disease (leaky valves) Congenital heart problems (PDA, VSD) Pulmonary hypertension (some) Cardiac arrhythmias due to hypoxia
    112. 112. Vasodilator Contraindications Hypotension Coronary artery disease (some) Poor cardiac contractility Tachycardias
    113. 113. Vasodilator Net Effects Decreased preload Decreased afterload Increases cardiac output Decreased workload of heart Antiarrhythmic
    114. 114. Hydralazine Pure Arterial dilator Uses--dogs with mitral regurgitation, hypertension Side effects in 50%--hypotension, GI side effects, increased pulmonary artery pressures
    115. 115. Nitrates Nitroglycerine ointment-- venodilator, no side effects, topical Sodium nitroprusside--IV, mixed vasodilator, metabolized to cyanide
    116. 116. Prazosin Arterial and venous dilator Metabolized in the liver Does not cause a reflex tachycardia Unknown if animals develop a tolerance to it or not.
    117. 117. Angiotension Converting Enzyme Inhibitors (ACE) Captopril (not used much b/c had many problems) Enalapril Benazapril Lisinopril Other ―Pril‖ drugs
    118. 118. ACE Inhibitors Stop conversion of angiotensin I to angiotensin II in lungs Decreases plasma aldosterone levels Increases blood flow to kidneys Effects are progressive
    119. 119. ACE Inhibitors Increases effects of thiazide diuretics Causes retention of potassium Does not cross blood brain barrier
    120. 120. ACE Inhibitors Used in: Dilated cardiomyopathy Mitral regurgitation Volume overloaded hearts (shunts such as PDA, VSD) Advanced heart disease in people
    121. 121. Enalapril Side effects uncommon-- hypotension Improves heart failure and increases survival Takes 7-10 days to reach maximum benefits Only one clinically tested in animals
    122. 122. Enalapril Hard to use in renal patients so use benazepril Improves dog’s quality of life and increases longevity Use in cat needs more study Not effective in horses, not absoped well in their GI tract
    123. 123. Beta Blockers’ Actions Decrease contractility (negative inotrope) Decrease heart rate Decreases myocardial oxygen consumption Blocks sympathetic stimulation of heart
    124. 124. Beta Blockers Used to slow AV conduction and slow heart rate with SVT Also used in hypertrophic cardiomyopathy
    125. 125. Beta Blockers Propranolol Atenolol Metroprol Carvedilol Other ―–ol‖ drugs
    126. 126. Beta Blockers Side Effects Blocking beta 1 receptors in heart will decrease contractility and heart rate Blocking beta 2 receptors cause bronchoconstriction Heart blocks Heart failure
    127. 127. Carvedilol Blocks beta 1 and beta 2 receptors Extends life span in people May help in dogs—studies ongoing
    128. 128. All Beta Blockers Start at low dose and increase gradually Do not stop abruptly Don’t start until heart failure under control
    129. 129. Additional Therapy Cage rest Low sodium diet Narcotics Removing accumulated fluids
    130. 130. Acute Pulmonary Edema Diuretics Cage rest with oxygen Nitrol ointment ACE inhibitors Hydralazine or nitroprusside Catecholamines
    131. 131. Pleural Effusion Thoracentesis—but do NOT stress Cage rest and diuretics
    132. 132. Chronic CHF Therapy Diuretics Venodilators—ACE inhibitors Treat the underlying heart disease with appropriate drugs Beta blockers
    133. 133. Pressure Overload Excessive afterload Systolic dysfunction Subaortic stenosis or pulmonic stenosis Pulmonary hypertension Systemic hypertension
    134. 134. Volume Overload Excessive preload Systolic dysfunction Mitral or tricuspid regurgitation Shunts--PDA, VSD
    135. 135. Pump Failure Systolic dysfunction Cardiomyopathies--dilated, myocarditis Chronic heart disease Dysynergy Drugs
    136. 136. Arrhythmias Changes in rate, rhythm, or conduction Affects heart rate, synergy and filling of the ventricles Effect depends on ventricular heart rate Bradyarrhythmias, tachyarrhythmias
    137. 137. Myocardial Restriction Diastolic dysfunction Restrictive cardiomyopathy Pericardial disease Tumors infiltrating myocardium Hypertrophic cardiomyopathy
    138. 138. High Output States Excessive tissue demands Shunts Anemia Fever Hyperthyroidism
    139. 139. Cardiac Preformance Preload Afterload Contractility
    140. 140. Cardiac Performance Distensibility Heart rate Synergy

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