Small Animal Endocardial Disease Flashcards
What is the most common cause of heart failure in the dog?
Valvular disease
What are the two forms of valvular disease?
Acquired form and congenital form.
(Acquired - chronic degenerative valvular disease (CVDV), endocarditis (rare), traumatic injury (very rare)).
(Congenital - valve dysplasia - insufficient valve, stenotic valve).
What are four alternative names for the same disease?
Chronic (mitral) valvular disease (CVD).
Chronic degenerative valve disease (CDVD).
Endocardiosis.
Myxomatous mitral valve disease.
What is the endocardium?
The thin, smooth membrane that lines the inside of the chambers of the heart and forms the surface of the valves.
What is the pathology of endocardial disease?
Myxomatous degeneration of MV and/or TV.
60% MV only, 30% both, 10% TV only.
Rarely affects aortic / pulmonic valves.
Thickening and redundancy of heart valve leaflets.
Most pronounced at the free margins of the valves.
Area becomes thickened.
Prominent nodular thickenings.
CDVD results in valve leaflet and CT abnormalities. Lengthening of the CT and redundancy of the CT and laxcity of the valve leaflets. This leads to MV prolapse. 1st see prolapse then thickening of the leaflet edges which then curl on themselves.
What is the structure of a valve in the heart?
4 distinct layers. Atrialis Spongiosa Fibrosa (connective tissue) Ventricularis
What is the histopathology of endocardial disease?
The elastic fibres between the spongiosa and atrialis spilt and seperate. Spongiosa increases in size while the fibrosa layer of the valve degenerates. Increase in ECM. Fibroblasts in the spongiosa proliferate forming swirls and small nodules. In the fibrosa layer the collagen bundles become swollen and hyalinised fragment and vanish. In severe cases only scattered remnants of the fibrosa remain. Similar changes in the CT.
What does a normal valve look like?
(see powerpoint - slide 16)
What is the histopathology of endocardial disease? (cont.)
Valve and CT composed of 4 layers.
Spongiosa layer proliferates.
Fibrous layer degenerates.
In severe cases only scattered remnants of the fibrosa layer remain.
Whitney classification:
Class I – small discrete nodules along edge of valve
Class II – thickened free edges and irregular
Class III – valve edges are grossly thickened and nodular with extension of lesions to the base of CT
Class IV – Further severity of Class III lesions.
Whitley classified the progression of the disease into 4 classes. Class I lesions are small, discrete nodules along the edge of the valve leaflet. The lesions coalesse to form larger deformities toward the free edges of the leaflet. Class II the free edges are thickened and the edges become irregular and more thickened as the disease progresses. Some thickened CT are thickened where they attach to the valve. Class III valve edges are grossly thickened and nodular the thickening extends part way and sometimes all the way to the base of the CT . In class 4 further severity of class 3 lesions.
What does the pathology of CVD look like?
(see powerpoint - slide 18).
What is stroke volume?
Stroke volume = EDV - ESV
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EDV = end diastolic volume
(ESV = end systolic volume)
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What is pre-load?
Degree of stretch on the heart before it contracts.
What is contractility?
Forcefulness of contraction of the individual ventricular muscle.
What is after-load?
Pressure that must be exceeded before ejection of blood from ventricles.
What are the factors that increase cardiac output?
(see powerpoint - slide 20).
