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
What does pressure overload of the left ventricle cause?
Concentric hypertrophy
What are the congenital features of AV valve dysplasia
- Shortening, Thickening and rolling of leaflets
- Direct insertion of valve edges onto papillary muscle
- atrophy/ fusion/ malposition of papillary muscles and chordae tendinae
What are transposition complexes?
Malpositioning of arterial trunks
What is the most common transposition complex?
Overriding aorta
* Aorta straddles IVS, receives blood from both ventricles,
What is Tetralogy of Fallot/ Partial transposition?
- Obstruction of Right Ventricle outflow due to abnormal conotruncal positioning
- overriding aorta
What is a persistent right aortic arch?
- Aorta forms from the right 4th aortic arch rather than the left
- The ductus arteriosus that connects the aorta wraps around the oesophagus -> causing megaoesophagus
- usually causes aspiration pneumonia
What is lusitropy?
The rate of myocardial relaxation
Why does left to right shunting result in increased left sided volume?
- All of the blood on the right side is pumped into the left side
- increased blood volume = increased preload for the LHS
What is the implication of aortic valve stenosis?
- Smaller aortic valve
- increases afterload
What is an overriding aorta?
Aorta lies over a heart defect
What is partial transposition?
Aorta and pulmonary artery are on the right hand side of the heart
What is complete transposition?
Aorta leaves the right ventricle
Pulomonary artery leaves the left ventricle
What is an overriding pulmonary artery?
Aorta leaves through the right ventricle, the Pulmonary artery ‘straddles’ a defective Intra ventricular septum
What is a partial transposition also known as?
Tetralogy of fallot
What does left to right shunting cause?
- Oxygenated blood from the left side flows into the right hand side
- Volume overload of the pulmonary circulation
- Therefore also volume overload of the left side as well
What is the most common cause of pulmonic stenosis in dogs?
Valvular
What valves are stenotic diseases most likely to affect?
Semilunar valves
What valves are most likely to be affected by stenotic diseases?
Semilunar valves
What valves are most likely to be affected by dysplastic diseases?
Atrioventricular
What does stenosis and subaortic stenosis look like grossly?
White band of thickened tissue
What is a frequent sequelae to persistent right aortic arch?
Aspiration pneumonia
