Cardiac Failure Flashcards
Heart Disease
Presence of any cardiac finding outside the accepted limits of normaility
Ex = mitral regurgitation, dilated cardiomyopthy, pulmonary stenosis
Myocardial Failure
Decrease in contractile capacity of the heart
ex = Systolic dysfunction
Heart Failure
Failure of heart to pump enough blood to satisfy the metabolic needs of the body
Response of body to a failing heart
1) FIRST = Increase in sympathetic nervous stimulation (IMMEDIATE) = baroreceptors = try to inc cardiac output
2) NEXT = Reabsorption of fluid by kidneys (days/weeks) = to inc cardiac output
3) FINALLY = remodeling of the heart (weeks/months) = to compensate for the problem
Sympathetic stimulation = Immediate response to heart failure
Increases Arterial P:
1) Constricts arterioles = inc in peripheral resistance (alpha receptors)
2) Constriction on large veins = decrease compliance = push more blood to the heart = inc cardiac output (alpha receptors)
3) Stimulating heart to increase heart rate and contractility (beta receptors
Retention of Fluid by the Kidney = 2nd response to heart failure
1) Decreased glomerular filtration = less fluid leaving the blood system
2) Activation of Renin-Angiotensin system = increase of sodium reabsorption and constriction of arterioles
3) Increased aldosterone secretion (due to Angiotensin II) = Inc water retnetion and water and ion reabsorption
TO ALLOW MORE FLUID TO RETURN TO THE HEART + INCREASE CARDIAC OUTPUT = INC ARTERIAL P
Moderate vs Long-Term fluid retention during cardiac failure
Moderate Fluid Retention in Cardiac Failure = BENEFICIAL
1) Increase in venous return helps to compensate for decreased pumping ability of the heart
2) When cardiac output returns to normal = no more fluid retention
Long-Term Fluid Retention in Cardiac Failure = DETRIMENTAL (severe cardiac failure since so much time has passed)
1) Overstretching Heart
2) Edema Formation (water fluid collecting in cavities)
Cardiac Remodeling = Final Response to Cardiac Failure
Pressure overload = aortic stenosis, hypertension = concentric hypertrophy of cells
Volume oveerload = valvular insufficiency (abnormal closure of heart valve) = eccentric hypertrophy of cells
Heart gets thicker
Myocytes get longer
Compensated Heart Failure
SUCCESSFUL RESPONSE TO CARDIAC FAILURE
1) Normal cardiac output DUE TO fluid retention in the kidney AND cardiac remodeling
2) HIGHER THAN NORMAL atrial P
3) Sympathetic stimulation GOES BACK TO BASAL RATE as long as cardiac rate remains normal
4) REDUCED CARDIAC RESERVE = normal cardiac output BUT exercise intolerant = cannot produce enough output
Decompensated Heart Disease
BODY”S RESPONSE TO CARDIAC FAILURE DID NOT WORK
1) Severely damaged heart
2) Cannot maintain cardiac output regardless of the body’s 3 attempt to inc it
3) Continuous progression of fluid retention in the kidney = progressive elevation of atrial P
4) Progressive EDEMA formation
Edema in Patients with Cardiac Failure
1) Left Cardiac Failure - fluids go backwards = CAUSES PULMONARY PROBLEMS
Produced by = mitral regurgitation, aortic stenosis, patent ductus arteriosis (PDA),
Causes = pulmonary edema, tachypnea, dyspnea coughing
2) Right Cardiac Failure - CAUSES PERIPHERAL PROBLEMS
Produced by - Cardiac Heartworm Disease, Pulmonary Hypertension
Causes = ascites (abdominal swelling), hepatomegaly (enlargement of the liver), peripheral edema
Treatment of Decompensation
Strengthening the heart, Diuretics, Angiotensin Converting Enzyme Inhibitors, Beta Bockers
3 disease states that lead to heart failure
1) Degenerative Mitral Valve Disease
2) Dilated Cardiomyopathy
3) Hypertrophic Cardiomyopathy
Degenerative Mitral Valve Disease
VOLUME OVERLOAD of heart = leakiness
Most common primary abnormality that causes AV regurgitation
Mild 75%
= GOES BACKWARDS
Higher on L side b/c more P
Mild Mitral Regurgitation in Small Dogs
Caused by Degenerative Mitral Valve Disease
, 50% regurgitant fraction
soft systolic murmur (clinically normal)
Inc Symp Tone
Inc end diastolic vol = normal stroke volume despite regurg (body’s response)
L VENT ENLARGEMENT (essentric hypertrophy) to accomodate end diastolic vol
Moderate Mitral Regurgitation
50-75%
Elevated end diastolic vol
moderate cardiomegaly
normal contractility and normal flow bc heart not big enough to cause probs yet
Retain fluids to lower BP
Severe Mitral Regurgitation
> 75%
Heart Failure
Forward stroke vol dec
Body cont to retain fluids
L vent can no longer inc in size
INCREASED:
L vent P
L atrial P
Pulm capillary P and pulm edema
Large dogs w/ degenerative mitral valve disease
Effects happen earlier and are more severe
need a new valve
Dilated Cardiomyopathy (DCM)
Myocardial failure present for unknown reason
systolic dysfunction = heart is not contraction
dilation of 4 chambers
L appear more severe than the R
Body response:
Inc symp tone
Inc fluid reabs
Eccentric hypertrophy
chamber can grow no more
pulm edema
NO DRUGS = MUST HAVE TRANSPLANT
Hypertrophic Cardiomyopathy
L Vent myocardium characterized by concentric myopathy = STIFF chamber = hard to push blood
MOST COMMON DIAGNOSED CV IN CATS
L vent chamber smaller than normal
enlarged L atrium
INC in:
L vent diastolic P
L atrial and pulm Ps
Inc pulm cap P = pulm edema
