Cardiovascular Pathology I Flashcards
What is the main job of the heart?
- To pump blood through the vasculature
- Meet the cardiac output demands and the waste disposal demands
What happens when the body demands greater output from the heart?
- The heart and vascular system employs mechanisms to compensate and meet demands (increase cardiac output)
- Cardiomyocytes contract more
- Increased flow and volume in the conduction system
What is pre-load?
Stretching of the cardiomyocytes just prior to contraction
What is after-load?
The force which the heart has to contract against to eject blood
What is inotropy?
The degree the muscle fibres shorten independent of the load
What is Frank-Starlings law?
Increased EDV and therefore pressure, increases the stroke volume
What does a persistently increased diastolic workload lead to?
pathologic dilation
* arteriovenous shunts
* AV and semilunar valve insufficiency
* Septal defects
* Fluid overloading
What is cardiac hypertrophy?
Reversible increase in mass with a minimal increase in the number of myocardial cells
* a compensatory response in order to increase mechanical work
When does concentric hypertrophy usually occur?
- Concentric hypertrophy is when the walls begin to thicken
- Usually occurs when there is a chronic pressure overload
increased resistance to the ventricles
When does eccentric hypertrophy occur?
- Occurs when there is a chronic volume overload
eccentric= elongation of the cardiomyocytes
What is physiological hypertrophy?
- Response to exercise or pregnancy
(increased cardiac output demand)
What is pathological hypertrophy?
- Decreased cardiac function
- associated with a change in workload
What are the three major arteriovenous connections present during cardiac embryology?
- between the aorta and pulmonary artery= ductus arteriosus
- Between the atria = foramen ovale
- separation of the ventricles
What is left to right shunting?
- High to low pressure
- Systemic -> Pulmonary (overload of pulmonary circulation)
What is Eisenmenger syndrome?
Vascular malformations lead to pulmonary hypertension
This leads to a reversal of the left to right shunting across pulmonary-systemic vasculature
What are some of the clinical findings of left to right pulmonary shunting?
- Exercise intolerance
- Syncope
- Dyspnea
- Sudden death
What three murmers might you see in systemic to pulomary shunting?
- PDA- continuous ‘washing-machine’ murmer
- VSD- right apical to basilar systolic, the smaller the defect the louder the murmer
- ASD- left basilar systolic
What is a patent ductus arterious?
An extra blood vessel between the aorta and pulmonary artery
What are the three atrial septal defects?
- Sinus venosus defects = (septum between right upper pulmonary veins and cranial vena cava)
- Ostium primum defect= failed fusion of septum primum with endocardial cushions
- ostium secundum defect = excessively large ostium
secundum (patent foramen ovale) = most common
What is a stenotic disease?
valvular malformation
aortic valve narrows and blood therefore cannot flow normally- affects the semilunar valves
(increases the afterload)
What is dysplastic disease?
valvular malformation
- an insufficincey -> increases the preload
- More common in the AV than the semilunar valves
What are the three different types of pulmonic stenosis?
narrowing of the valve
- Subvalvular, valvular, supravalvular
How is pulmonic stenosis caused?
- Pulmonary outflow tract hypertension -> Pressure overload of the right ventricle -> RV concentric hypertrophy
In english bulldogs- > caused by circumpulmonary left coronary artery
What is the most common form of aortic and subaortic stenosis in dogs and pigs?
Subvalvular
