Endocardial disease Flashcards
What is endocardial disease?
= valve disease
What are the 2 forms of endocardial dz?
Acquired form
- chronic degenerative valvular dz (CDVD) -> most common form of heart dz in practice
- endocarditis (rare) -> traumatic injury (very rare)
Congenital form - valve dysplasias
- insufficient valve
- stenotic valve
Different names for chronic degenerative valve disease
- chronic (mitral) valvular disease (CVD)
- chronic degenerative valve disease (CDVD)
- endocardiosis
- myxomatous mitral valve disease
How does CDVD occur?
- myxomatous degeneration of mitral ± tricuspid valve
- 60% mitral only, 30% both, 10% tricuspid only
- rarely affects aortic/pulmonic valves in small animals
- thickening and redundancy of heart valve leaflets
- prominent nodular thickening
CDVD histopathology
- valve has 4 layers - fibres -> chordae tenidae affected -> could rupture / unattach
Whitney classification of degeneration of the valve
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
Why does valvular degeneration cause a problem?
- as the valve gets thicker, it doesn’t shut adequately
- blood regurgitation from ventricles to the atrium
- regurgitation = end diastolic volume bigger and end systolic diameter smaller
- stroke volume increases, forward output falls
AKA
- more blood can enter the ventricle at any time -> higher than usual therefore more is pumped out of the ventricle (high stroke volume) but proportion is pumped backwards
- less blood is then ejected around the body due to regurgitation therefore less blood reaches the circulation
CDVD signalment
- middle -> older age
- smaller breeds overrepresented (congenitally prone)
– CVCS
– poodles
– chihuahua
– maltese
– shih tzu
CDVD presentation
If in congestive failure
- exercise intolerance
- increased resp rate and effort
- coughing
- decreased appetite
But may just have a murmur with no other CS
- if mitral valve (most common) -> PMI left apex
- if tricuspid -> PMI right apex
Grading heart murmurs
Grade I - quiet only heart after few mins in quiet room.
Grade II - quiet but easily audible.
Grade III - same intensity as heart sounds.
Grade IV - murmur louder than heart sounds but no precordial thrill.
Grade V - very loud murmur and precordial thrill.
Grade VI - murmur audible when stethoscope removed from chest wall.
OR
Mild - 1-2.
Moderate - 3-4.
Severe - 4-5.
Signs of significant heart disease?
- Grade 3 murmur or louder
- HR >120
- loss of sinus arrhythmia
- pre-cordial thrill
- dysrhythmia
- pulse deficits
- weight loss
- signs of congestive faolure
if any of the above -> investigations needed.
if < grade 3, well in self, could leave for some time but will likely get worse so always offer investigation.
Staging heart disease in dogs
Stage A - dogs at high risk for heart dz (no dz present at this stage).
Stage B - a murmur is heard but there are no visible signs of heart failure.
Stage B1 - the heart doesn’t appear enlarged or changed on x-ray.
Stage B2 - the heart does appear enlarged or changed on x-ray.
Stage C - evidence of heart failure is visible and tx is necessary.
Stage D - heart failure is getting hard to manage and is not responding to standard tx.
Investigations
- echocardiography: dz diagnosis and staging
- thoracic radiography: fluid, cardiac enlargement, staging
- electrocardiogram: assess rhythm
- biochemistry: renal, liver dz, other systemic dz
- haematology: anaemia, polycythaemia, WBCc
- blood pressure: hypertension?
- cardiac biomarkers: pro-BNP, troponin
Radiographic abnormalities of mitral regurgitation
Left sided cardiomegaly
- elevation of distal trachea
- increased cardiac silhouette height
- straightening of caudal border of the heart and loss of cardiac waist
- ‘tenting’ of LA
- splitting of mainstem bronchi
- bulge on cardiac silhouette at 2-3o’clock in DV = LA appendage
Use of pro-BNP
- marker of muscle damage
- doesn’t help with diagnosis or staging of heart disease
