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58 Cards in this Set
- Front
- Back
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Stroke Volume
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The volume of blood ejected w/ each heart beat
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Cardiac Output
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The volume of blood pumped by the heart during one minute
CO= SV x HR |
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4 Determinants of Cardiac Output
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Heart Rate
Preload Afterload Contractility |
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Effect of Heart Rate on Cardiac Output
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↑ in HR= ↑ in CO
except when HR is so fast ventricular filling is inadequate |
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Effect of Preload on Cardiac Output
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↑ in Preload= ↑ in CO
(More forceful contractions, larger stroke volume) Direct relationship |
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Effect of Afterload on Cardiac Output
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↑ in Afterload= ↓ in CO
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Preload
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the force that stretches the myocardium prior to contraction
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Afterload
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the forces that oppose ventricular ejection
Related to aortic pressure & Peripheral vascular resistance |
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Contractility
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the intrinsic ability of myocardium to shorten
("the strength" of the myocardium) Dependent upon autonomic activity |
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Inotropic state
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the level of contractility of the myocardium
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Effect of Contractility on Cariac Output
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Positive Inotropic intervention= ↑ Stroke volume = ↑ Cardiac Output
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Definition of Heart Disease
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A structural or functional abnormality of the heart
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Definition of Circulatory Failure
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the Cardiovascular system is unable to deliver adequate oxygen & nutrients to tissues
(SHOCK) |
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Heart Failure
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The potential consequence of any cardiac disease
A syndrome of clinical signs & neuroendocrine abnormalities resulting from impaired emptying or filling |
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Forward Heart Failure
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(LOW OUTPUT)
Clinical signs result from poor perfusion, such as hypothermia & pre-renal azotemia |
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Backwards Heart Failure
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(CONGESTIVE)
Clinical signs result from high venous pressure Most common Heart failure in animals |
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Right-sided (congestive) heart failure
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Signs=ascites, pleural effusion, peripheral edema
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Left-sided (congestive) heart failure
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elevations in pulmonary venous pressure that causes lung edema
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Anatomical Classifications of Heart Disease
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Pericardial Disease
Myocardial Disease Endocardial Disease (includes valvular disease) Diseases of the conduction system |
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Pathophysiologic Classifacations of Heart Disease
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More Useful (MAIN) Classifications
Volume Overloads Pressure Overloads Contractile Dysfunction Diastolic Dysfunction Arrhythmias High Cardiac Output States |
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Characteristics of Volume Overloads
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Diseases that increase diastolic volume of the heart
i.e. valvular incompetence & shunts |
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Characteristics of Pressure Overloads
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Diseases that increase resistance to ventricular emptying
i.e. aortic/pulmonary stenosis, pulmonary hypertension |
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Characteristics of Contractile Dysfunction
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Functional or structural disorder of the sarcomeres can be cause, A.K.A. dilated cardiomyopathy
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Characteristics of Diastolic Dysfunction
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Diseases that impair ventricular fillinf
i.e. hypertrophic & restrictive cardiomyopathy, pericardial disease |
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Arrhythmias
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Abnormal cardiac rate/rhythm, can result in syncope or heart failure
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Characteristics of High Cardiac Output States
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conditions may cause or lead to heart failure
i.e. hyperthyroidism, chronic anemia, AV fistula |
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4 Questions to answer with Cardiovascular exam
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What's cardiac rate & rhythm?
Is heart enlarged? Is CHF present? If present, what's causing it? |
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Diagnosis of Left-sided CHF
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Radiographic Pulmonary edema, & cardiac dysfunction (see as left atrial enlargement radiographically)
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Diagnosis of Right-sided CHF
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Presence of ascites w/radiographic cardiac enlargement or jugular distention
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Most common cardiac diseases of dogs
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Chronic, progressive disorders, see left atrial enlargement prior to clinical signs of heart disease or left-sided CHF
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Most common cardiac disease affecting cats
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Myocardial disease, though thoracic rads no very useful in determining the true nature
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Echocardiogram
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(Cardiac Ultrasound), allows visualization of structural & functional information, exact measurements of the chambers
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Uses of Doppler Echocardiogram
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Provides info about blood flow, velocity, direction & character
Used to localize disturbances in flow |
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Primary use of Electrocardiogram
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the "elucidation of cardiac rhythm disturbances"=to determine arrhythmias
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When to take Thoracic Rads for cardiology
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When clinical signs indicate: cough, dyspnea
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When to use Echocardiogram
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When the cause of enlarged cardiac silouhette is unclear or need a more definitive diagnosis
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Orthopnea
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Discomfort breathing in any but the standing position
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Significance of a nocturnal cough
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Common in left-sided heart failure
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Thrill
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Palpable turbulence from a heart murmur, best felt with the palm of the hand
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PMI
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Point of Maximum Intensity
Area at which the beat feels the strongest |
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Tricuspid Valve
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Separates Right Atrium --> Ventricle
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Mitral Valve
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Separates Left Atrium --> Ventricle
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Pulmonary valve
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Separates Right Ventricle --> Pulmonary artery
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Aortic valve
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Separates left Ventricle --> Aorta
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Significance of P wave
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Represents Atrial depolarization
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Significance of QRS complex
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Represents Ventricular depolarization
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Significance of T wave
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Represents Ventricular repolarization
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Source of 1st Heart Sound
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AV valves closing
Semilunar valves opening |
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Source of 2nd Heart Sound
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Semilunar valves closing
AV valves opening |
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Source of 3rd Heart Sound
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Rapid passive filling of the ventricles after systole
Only normal when heard in the horse |
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Source of 4th Heart Sound
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Contraction of the atria & the active movement of blood into the ventricles
Only normal when heard in the horse |
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Areas of Auscultation on the left side
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Pulmonic
Aortic Mitral Thoracic inlet |
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Areas of Auscultation on the right side
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Tricuspid
Thoracic inlet |
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Systolic clicks
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usually beniegn, best heard over mitral/tricuspid valves
high frequency and labile sounds |
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Diastolic heart sounds
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Third heart sound
Fourth heart sound |
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Third heart sound
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low pitched sound from rapid ventricular filling
best heard @ the apex |
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Fourth heart sound
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occur @ the beginning of atrial systole, right before S1
best heard @ apex |
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Summation gallop
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fusion of the S3 & S4
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