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166 Cards in this Set
- Front
- Back
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What is CO equal to?
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the volume of blood pumped by the heart in one minute
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What is SV?
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the volume of blood that the heart ejects each systole.
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What four principle factors help determine CO?
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(1) HR - direct relationship unless HR is so rapid it impairs filling
(2) preload - direct relationship (to SV - Frank Starling Law) (3) Afterload - inversely related (the forces that oppose ventricular ejection) (4) contractility - directly related |
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How can afterload be manifulated pharmacologically?
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vasodilators
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What is an important determinant of afterload?
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Peripheral vascular resistance
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What do positive inotropes do?
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increase SV and CO
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What is the definition of heart failure?
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a syndrome of clinical signs that results from impaired emptying or filling of the heart
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What results from LV CHF?
-RV CHF? |
LV CHF= pulmonary edema
RVCHF = ascites |
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What are the anatomical designations for heart failure?
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(1) pericardial
(2) myocardial (3) endocardial/valvular (4) conduction system |
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What are the primary pathophysiological classifications of heart disease?
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(1) Volume overloads
(2) contractile dysfunctions (3) Diastolic Dysfunction |
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What are two examples of volume overloads (disease that increase diastolic volume of the heart)?
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-valvular incompetence
-shunts |
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Give an example of contractile dysfunction?
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-dilated cardiomyopathy
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Give three examples of diastolic dysfunction (impair ventricular filling).
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-hypertrophic cardiomyopathy
-RCM -pericardial disease |
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Give 3 examples of pressure overloads (increase systolic load, often because of increased resistance to ventricular filling) .
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--aoritic stenosis
-pulmonary stenosis -pulmonary hypertension |
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What is heart disease?
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any structural/functional cardiac abnormality (sub or clinical)
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When heart disease is noted in young patients, it is most likely what?
-old patients? |
-congenital
-degenerative |
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Do cats with heart disease cough?
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rarely
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In amimals that are athletes, exercise intolerance may mean what?
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mild heart disease
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What can often be confused with heart disease in animals?
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respiratory problems
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When a cardiac disease explains a syncope, what is often responsible?
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-an arrhythmia
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Sudden respiratory distress is often a sign of what?
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-cardiogenic pulmonary edema
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Failure to thrive in patients may mean what?
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a congenital malformation
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What is the pulse in a canine?
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70-160
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What is the pulse in a feline?
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160-240
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What is the pulse in a horse?
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24-50
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What is the pulse in a cow?
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60-110
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Other than the femoral artery, where can a pulse be felt?
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dorsal pedal, brachial, facial, digital, median tail, coccygeal
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What are 2 important characteristics of a pulse?
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-strength (amplitude)
-quality |
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Pulse amplitude is most closely associated with what?
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Pulse pressure = SP-DP
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What 5 things does pulse pressure depend on ?
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(1) SV
(2) HR (3) aortic distensibility (4) EDV of arteries (5) resistance to flow - rate at which blood leaves the arterioles |
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What does the hypokinetic arterial pulse reflect and what is it most likely related to?
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-decrease in SV
-related to hypovolemia or heart disease |
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An absent arterial pulse is due to what?
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-obstruction due to a thromboembolism
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What does the hyperkinetic arterial pulse reflect and what is it most likely related to?
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-increase in pulse pressure
-anemia, hyperthyroidism, aortic valve insufficiency (AI), PDA |
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What does central venous pressure reflect?
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-height of the jugular pulsation reflects right atria and ventricular pressure
-evaluated at standing position |
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What is suggested when the jugular vein is distended above 8 cm ?
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-right heart failure - volume overload (diastolic filling pressure)
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Is CRT sensitive to decreases in CO?
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no
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What does a decrease in pallor of the mucous membranes mean physiologically and what are the 2 primary causes?
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-due to LESS OXYhemoglobin in the cap. bed
-anemica and peripheral constriction |
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What does cyanosis of the mucous membranes mean physiologically and what are the 2 primary causes?
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-when DEOXYhemoglobin is visible in the vasculature (exceeds 4 g/dL)
(1) peripheral cyanosis (stasis of the blood) DUE to LOW CO or THROMBOSIS if localized (2) central cyanosis DUE to lung disease and rarely due to heart defects |
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Where is PMI?
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over the left apex
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What is a thrill associated with?
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a high intensity murmur
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What is done prior to asculttion?
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precordial palpation over the PMI
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What is S1associated with?
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AV valve closure
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What is S2 associated with?
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semilunar valve closure
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What is S3 associated with?
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early diastolic filling
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What is S4 associated with?
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atrial contraction
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Is S1 higher or lower frequency than S2?
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lower
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What does that time between S1 and S2 represent?
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systole
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What is splitting of heart sounds?
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-the separate sounds of S1 (mitral valve heard first then tricuspid) or the sounds of S2
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What can cause delayed semilunar valve closure (prolonging systole)?
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-outflow tract stenosis
-volume load -bundle branch block/premature complexes -associated with respiration |
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What could cause delayed AV valve closure - causing a splitting of heart sounds?
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-bundle branch block
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When is a systolic click heard and what is it associated with?
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-high freq sound heard mid-systole
-associated with mitral valve prolapse |
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Systolic clicks are common in what types of dogs and are a precursor to what?
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-older, smaller breed dogs
-precursor to mitral valve regurgitation |
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What is a gallop rhythm?
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audibility of the S3 or S4 heart sounds
-not an arrhythmia -heard when atrial pressures are high and ventricle is close to its elastic limit |
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Is a gallop rhythm a specific marker of heart disease?
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yes - in dogs and cats
BUT heard in HEALTHY horses (S3) |
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What does a murmur reflect?
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-break down of laminar blood flow to turbulent flow
-it is a prolonged series of vibrations |
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What are the 3 determinants of blood flow character?
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(1) velocity=acceleration explains MOST murmurs
(2) viscosity=anemia when HCT is less than 17 (3) Vessel diameter |
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How are murmurs characterized?
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(1) intensity
(2) timing (3) PMI (location) |
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How many grades are there to the intesisty of murmurs?
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6
Grade 1 - very soft and focal Grade 6 - loud murmur with thrill and audible if lifted from chest |
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How is the timing of a murmur characterized?
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(1) systolic
(2) diastolic (3) continuous - begin during systole, persist after S2 (PDA!) |
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What is the PMI for aortic and pulmonic areas?
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left heart base
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What is the PMI for mitral valve?
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left apex
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Where are most murmors in cats heard?
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along the sternal borders
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What does configuration of a murmur mean?
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the phonographic shape
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What is the configuration of an ejection murmur that results from outflow tract obstruction?
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diamond - that is it is loudest mid-systole
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What is the configuration of a reguritant murmur and what is it caused by?
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-same thruout
-mitral valve regurg |
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What are innocent murmurs?
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occur in the absence of structureal CD in animals that are normal (puppies, kittens, horses (adult)
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Functional flow murmurs are associated with what?
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-when SV increases, ejection velocity must also increase to keep systole the same
-thyrotoxicosis, fever, athleticism |
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What are the 2 electrophysiologically distinct populations of cells in the heart?
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(1) specialized conduction cells= pacemakers that depolarize spontaneously (exhibit automaticity)
-SA node is dominant and fastest (2) working cardiomyocytes |
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What does the EKG actually measure?
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potential differences
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What is the ECG used for?
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provides information on the rate, rhythm, and cardiac size (chamber enlargement), as well as ischemia
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What is the primary utility of the ECG?
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to diagnose arrhythmia
-when the heart rate is too fast, too slow or inappropriately irregular |
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What is the x and y axis of an ECG?
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x - time
y - voltage |
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What 2 things are controled by the operator when performing an ECG?
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-paper speed - usually 50 or 25 mm/sec
-sensitivity - usually 1mV=1 cm |
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What is the positive pole of lead 2 attached to?
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left leg
-QRS in lead 2 is normally positive |
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What does P mean on an ECG?
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atrial depolarization
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What does QRS mean on an ECG?
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ventricular depolarization
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What does T mean on an ECG?
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ventricular repolarization
-can be pos or neg or biphasic |
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Is the normal QRS wide or narrow?
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narrow
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What is the mean electrical axis
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-dominant vector of ventricular activation ( wave of cardiac activation is a vector with direction and magnitude)
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What is the origin of a narrow QRS?
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supraventricular
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What is the origin of a wide QRS?
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ventricular
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Clinical Signs such as syncope, low CO and sudden cardiac death are signs or what?
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arrhythmia
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What is the definition of arrhythmia?
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any deviation in normal sinus rhythm
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When disease of the conduction system prevents initiation or propagation of the wave front (AV block or SA node disease, this explains)...
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bradyarrhythmias
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When disease of the myocardium causes spontaneous depolarization of working myocyte (premature complexes), this explains...
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tachyarrythmias
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What are some causes of tachyarrhythmias?
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(1) structural cardiac disease (DCM)
(2) extra cardiac disease --> electrolyte abnormalities, acid base disturbances, autonomic imbalance |
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What are some causes of bradyarrhythmias?
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(1) Disease of the conduction system (slows the rate of depolarization or blocks conduction)
(2) Autonomic factors - high vagal tone |
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What is the basic approach to EKGs?
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(1) HR
(2) Rhythm - regular or irregular - do they change abruptly; is there a pattern (3) Association between atrial and ventricular activity - P wave before QRS and is the PR interval consistent and believable |
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What does a sinus rhythm look like?
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P wave is normal and precedes a QRS wave by a consistent and believable PR interval; HR is normal
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During a sinus arrhythmia that only difference between it an a sinus rhythm is that the RR interval increases during what?
uncommon in what? |
inspiration
- cats in hospital |
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What is needed for the development of a sinus arrhythmia?
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vagal influence and often accompanied by a wandering pacemaker
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What is the difference between sinus tachycardia and sinus bradycardia and sinus rhythm?
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just the increase and decrease of the HR (outside the boundary of the normal heart rate)
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What is sinus tachycardia associated with?
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fear, anxiety, pain, excitement (normal physiologic)
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What is sinus bradycardia associated with?
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vagal tone is high - athletes, norm in sleeping individuals
(physiologic) |
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What are the characteristics of a supraventricular premature complex
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(1) occur early and result in a decrease in RR interval
(2) have a narrow QRS (3) P wave is absent or has an abnormal morphology - often overlapping with T wave (4) associated with diseases that cause atrial distension |
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What are the characteristics of SVT?
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(1) regular
(2) start and stop abruptly (3) QRS is narrow |
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What does fibrillation mean?
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disorganized electrical activity
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What are the characteristics of atrial fibrillation?
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(1) rapid
(2) irregular (3) NO P wave (4) QRS complexes all look the same and are normal (5) associated with disease that result in atrial distension (DCM in dogs) |
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What animal is atrail fibrillation sometimes normal in?
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horse and giant breeds b/c need lots of mass
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What are the characteristics of the ventricular premature complex (VPC)?
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-occur early
-are wide and strange -associated with structural disease or extracardiac disease |
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What are the characteristics of ventricular tachycardia?
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(1) rapid
(2) regular (3) initiated by a VPC (4) often associated with structural disease |
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What can ventricular tachycardia cause signs of and what can it degenerate to?
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-signs of low CO
-can degenerate to ventricular fibrillation (death) |
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What is sometimes the prodrome of severe myocardial dysfunction in Dobermans and Boxers?
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Ventricular Tachycardia
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What is VTA in Extracardiac Disease associated with?
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-trauma
-GDV - bloat - deep chested dogs -splenic disease -neurologic disease -sepsis |
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What are the characteristics of VTA in extracardiac disease?
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-slow (less than 160 bpm)
-initiated by late diastolic ventricular complexes -well tolerated by the patient |
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AV blocks resolve after the administration of what?
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atropine
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What is AV block related to?
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-functional and related to elevated vagal tone
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What are the characteristics of a 1st degree AV block?
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-prolonging of the PR wave
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What are the characteristics of a 2nd degree AV block?
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-intermittent failure of AV conduction
-P waves that are not followed by a QRS |
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What are the characteristics of a 3rd degree AV block?
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complete failure of AV conduction
-ventricle takes over and QRS is wide and bizarre -lots of P waves at a rapid rate, but ventricle rate is only about 20 bpm |
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What does a high grade 2nd degree AV block normally result from?
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idiopathic fibrosis and occasionally associated with myocardial disease, aortic valve endocarditis
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What is an important cause of syncope?
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complete AV block
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What breed does sick sinus syndrome most often occur in?
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older miniature schnauzers and dachsunds
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What is sick sinus syndrome most commonly manifested as?
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syncopal episodes
-sinus pauses, sinus bradycardia, sometimes SVT |
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What are characteristc of hyperkalemia on an ECG?
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-wide QRS
-P waves of low amplitude -peaked T waves |
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What is associated with hyperkalemia cardiac rhythm?
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urethral obstruction
-oliguric renal failure -addison's disease |
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What do arrythmias cause?
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syncope/sudden death
-contribute to poor perfusion in the critically ill |
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How are tachyarrhythmias treated?
brady? |
-drugs
-pace makers |
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How are most forms of Congenital Heart Disease found?
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the presence of a murmur, with usually no outward clinical signs at the time
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How are congenital heart disease most appropriately treated?
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mechanically
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Which way does a PDA normally shunt? Which side of the heart then has a volume overload?
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left to right shunt
-overload of left atrium and left ventricle |
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What are potential consequences of a PDA?
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myocardial dysfunction, mitral valve regurgiation and congestive heart failure
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What is the signalment of PDAs?
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small breed dogs, females more common
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What is always found with a PDA?
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a continuous murmur and bounding arterial pulse
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What are radiographic findings of a PDA?
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-cardiomegaly due to left atrial and ventricular enlargement
-pulmonary hyperperfusion -dilation of aorta and MPA |
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What are ECHO findings of a PDA?
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-LAE/LVE
-mitral valve regurgitation -continuous disturbed flow in the MPA -ductus visible in left cranial parasternal images |
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What is the therapy of a PDA?
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-ligation following left lateral thoracotomy or
-transcatheter ductal occlusion (ACDO) with fluroscopy placement (small patients may not be possible, so angiographic characterization is required to determine success) |
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What is PS most often due to?
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dysplasia of the valve (type 2 PS)
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Is the pressure high or low in the RV with PS?
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very high systolic pressures to maintain flow and pressure
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What is a potential sequella to PS?
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right side CHF (ascites)
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what is the signalment of PS?
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terriers OEBD
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What is the physical finding of PS?
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-systolic murmur at the left heart base
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What is required for a definitive diagnosis of PS?
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Doppler ECHO and assessment of severity
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What is considered a severe gradient in PS?
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gradients greater than 80 mmHG
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What are therapies for PS?
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-pulmonary balloon valvuloplasty - preferred as initial management when treatment indicated
-Surgery: patch graft following temporary venous occlusion; definitive repair under cardiopulmonary bypass |
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Do you treat an animal with PS and a gradient above 80 mmHg even if there are no clinical signs?
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yes
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If untreated, PS may cause what?
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CHF - which generally occurs in the first three years of life - or sudden unexpected death
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Where is the fibrous ring normally in subvalular aortic stenosis?
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subvalvular
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SAS imposes a pressure overload on what?
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the left ventricle
mild - less than 40 mmHG severe - greater than 80 -estimated from Doppler |
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What is the signalment of SAS?
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large breed dogs
-even mild SAS has genetic implications -inherited as a polygenic trait in Newfoundlend dogs -Goldies, Rotties, Boxers -clinical signs in puppies are uncommon |
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What is required for definitive diagnosis of SAS?
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Doppler - wen a murmur is detected
-BUT auscultation is the accepted screening methods |
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What are the radiographic findings of SAS?
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maybe cardiac enlargement
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What are the physical findings of SAS?
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-systolic murmur over the left heart base
-weak hypokinetic arterial pulse |
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What is the therapy for SAS?
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-definitive surgical correction requires cardiopulmonary bypass (may not affect survival)
-beta blockers may be helpful in decreasing heart rate and oxygen demand |
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Patients with SAS are at risk of what?
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sudden cardiac death
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Where are most VSDs?
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permembranous or high
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As isolated VSD results in what type of shunting and overload?
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-left to right shunt and LA/LV volume overload
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What does the clinical importance of a VSD depend on?
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-size of the defect
-presence of other defects |
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What is the signalment of VSD?
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-common in cats
-bloodhounds, english bulldog, shiba inu are predisposed |
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What are the physical findings of a VSD?
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-an isolated VSD results in a systolic murmur - restrictive defects typically associated with a right apical thrill
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What is teh definitive diagnosis for a VSD?
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Doppler
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What is the therapy for a VSD?
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most are small and don't require therapy
-FOR LARGE - surgery under bypass or medical therapy |
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A left to right atrial septal defect imposes a volume load on what part of the heart?
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right atrium and venticle
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What is the murmur associated with a ASD?
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-a functional PS (acceleration thru the valve)
- not hearing the actual shunt |
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How is an ASD fixed?
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-uncommon, but cardiopulmonary bypass
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What can AV valve dysplasia result in?
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regurgitation or stenosis of the mirtal or tricuspid valves
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AV valve dysplasia is common in what breed?
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cats
-Tricuspid VD common in LABS |
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How is AV valve dysplasia fixed?
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cardiopulmonary bypass
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What does cyaotic heart disease result from?
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right to left shunts
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What are prerequisites for cyanotic heart disease?
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-markedly elevated right atrial, right ventricular and or pulmonary artery pressures
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Cyanotic heart disease results when there is a shunt AND what?
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-tricuspid stenosis
-pulmonary stenosis -pulmonary hypertension associated with elevated pulmonary vascular resistance |
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What are clinical signs of cyanotic heart disease?
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-exercise intolerance
-complications of polycythemia (release of EPO from kidney is a result of hypoxia) makes the blood more viscus and more chance for a thrombus |
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Why is polycythemia associated with cyanotic heart disease?
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-the kidney is releasing EPO
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What is Eisenmenger's Physiology?
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elevated pulmonary blood flow can result in vascular disease and shunt reversal (right to left PDA)
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What is the therapy for shunt reversal?
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therapeutic phlebotomy when RBCs are high
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What are the components of Tetralogy of the Fallot? - a cyanotic heart disease
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-PS
-VSD -RVH (right ventricular hypertrophy) -aortic malposition |
