Cardiovascular system Flashcards
Flow of blood in heart
- Superior or inferior vena cava
- Right atrium
- Tricuspid valve (diastole)
- Right ventricle
- Pulmonary valve
- Pulmonary artery (de02 blood)
- Lungs
- Pulmonary vein (oxygenated)
- Left atrium
- Mitral valve
- Left ventricle
- Aortic valve
- Aorta and to the body!!!!
Layers of the heart (out to in)
Pericardial sac
Parietal pericardium
Visceral pericardium (epicardium)
Myocardium
Endocardium
Electrical conduction of the heart
SA node
AV node
Bundle of HIs
Purkinje fibers
Function of the cardiovascular system
Maintain circulation of blood
Molecular exchanges
Thermoregulation
Urine output
Cardiac output
HR x SV
heart rate x vol. of blood pumped per beat of ventricle
_____________ functional cardiac reserve capacity
3-5 fold
how much the heart can compensate
Compensatory response to ↑ workload
Cardiac dilation (from myofiber stretching)
Acute transient overload (physiolocal dilation)
Chronic volume overload (dilation + hypertorphy)
Cardiac hypertrophy
LV: ↑ in length
RV: heart has broader base (backward D shape)
Concentric and eccentric
What’s needed for cardiac hypertrophy?
Time, healthy myocardium, and myocardial nutrition
Concentric hypertrophy
↑ myocardial mass and thickness of ventricular wall WITHOUT ↑ diameter of chamber
What causes concentric hypertrophy?
Pressure overload from aortic or pulmonary stenosis (narrowing), pulmonary hypertension
*Hyperthyroidism in cats
Eccentric hypertrophy
↑ myocardial mass of ventricular wall and +/- thickness, WITH ↑ diameter of chamber
What causes eccentric hypertrophy
Volume overload due to vascular insufficiencies (pulmonic, aortic, atrioventricular)
Vascular insufficiencies
Valves don’t close completely after systole → blood forced back up into the atrium → diastole → extra blood going back into ventricles
Frank-Starling mechanism
↑ force of contraction of myocardium by ↑ load of ventricles by stretching fibers and ↑ strength of contraction
Heart failure
Occurs when the heart can’t compensate: cardiac output ↓, cardiac enlargement
Causes of heart failure
Sustained pressure overload
Sustained volume overload
↓ normal contractility
Congestive Heart failure
Cardiac output can’t keep pace with venous return
↓ stroke vol. and rate of contraction
Pulmonary (left) and generalized (right) venous congestion
Small dog breeds with CHF
Geriatric: mitral regurgitation due to endocardiosis (most common)
Large and giant breeds with CHF
Dilated cardiomyopathy (most common)- biventricular but LV most effected
Boxer CHF
Arrhythmogenic right ventricular cardiomyopathy
Cat with CHF
Hypertrophic and cardiomyopathy
Inherited autosomal dominant trait in Maine Coon and American Shorthairs
1-3 yrs - sudden death
Left sided heart failure
Primarily effects the lungs: congestion, edema and induration
Coughing and shortness of breath (dogs)
Brown induration of the lungs (left sided heart failure)
Deposition of hemosiderin in the lung macrophages forming heart failure cells → thick pulmonary pleura, firm, chronic
CS of brown induration
Coughing, fluid in alveolar spaces, golden appearance to lungs, macrophages with hemosiderin
Right sided heart failure
Generalized effects: venous congestion, distention of liver, spleen and jug vein
Distribution of fluid for right sided heart failure
Cat: thorax
Dog: peritoneum
Horse: SQ edema (legs- stocking)
Cow: SQ edema (brisket)
Brisket disease
Cattle and swine
Hypertensive heart failure at high altitudes (right sided heart failure)
SQ edema on the brisket
Brisket disease pathogenesis
Hypoxia induced vasoconstriction → tunica media hypertrophy of pulmonary arteries and arterioles → pulmonary hypertension → right ventricular dilation and hypertrophy → cardiac decompensation if chronic → chronic HF
