Small Animal Endocardial Disease Flashcards
What are some of the names used for valvular disease in the dog?
Chronic (mitral) valvular disease (CVD)
Chronic degnerative valve disease (CDVD)
Endocardiosis
Myomatous mitral valve disease
What can be seen on thoracic radiographs of dogs with mitral valve disease?
- Enlarged cardiac silhouette (straightening of distal trachea, straightening of caudal border, tenting of LA)
- Increased radiodensity in caudal dorsal lung fields with some border obliteration
- Alveolar pattern
What are the typical findings on clinical exam of a dog with valvular disease?
Heart murmur (PMI left apex, radiates dorsally and to right thorax), often get very loud S1 Crackling lungs
What happens in the heart during chronic degenerative valvular disease (acquired)?
Valve leaflet and CT abnormalities
Lengthening of the CT, redundancy of the CT and laxity of the valve leaflets
Mitral valve prolapse
Thickening of the edges of the valve leaflets which then curl in on themselves
What are the 4 layers of a valve?
Atrialis
Spongiosa
Fibrosa (tougher area of the valve, contiguous with the chordae tendinae)
Ventricularis
Describe the Whitney classification of valvular degeneration (I-IV)
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
What is preload?
Degree of stretch on the heart before it contracts
What is contractility?
Forcefulness of the contraction of the individual ventricular muscle
What is afterload?
Pressure that must be exceeded for ejection of blood from ventricles
What factors increase stroke volume?
Increased pre-load, increased contractility, decreased after-load
What factors increase cardiac output?
Increased stroke volume and increased heart rate
What is the signalment for valvular disease?
Middle-old age Small breeds (cavalier king Charles, poodles, maltese, etc.)
What is the typical history of a patient with congestive heart failure?
- Increased respiratory rate and effort (due to pulmonary oedema)
- Coughing (often during night/early morning)
- Exercise intolerance
- Decreased appetite
Describe the characterisation and grading of heart murmurs
o Grade I- quiet, only heard after a few minutes in a quiet room
o Grade II- quiet but easily audible
o Grade III- same intensity as the heart sounds
o Grade IV- a murmur louder than heart sounds but no precordial thrill
Precordial thrill vibration felt on chest wall due to transmission from turbulent blood flow
o Grade V- very loud murmur and precordial thrill present
o Grade VI- murmur audible when stethoscope removed from chest wall
Alternative grading:
o Mild- 1 and 2
o Moderate- 3 and 4
o Loud with thrill- 5 and 6
When is heart disease classed as significant?
- Grade III murmur or louder (without anaemia)
- Heart rate > 120bpm
- Loss of sinus arrhythmia
- Precordial thrill
- Dysrhythmia +/- pulse deficits
- Weight loss?
What will be seen on thoracic radiographs in patients with CHF?
o Cardiac enlargement
o Engorged pulmonary vessels
o Pulmonary oedema (L-CHF)
o Starling forces mean that fluid will leak out of capillaries first, therefore oedema fluid into interstitium first
What might be seen on an electrocardiogram of a dog with valvular disease?
o +/- tachycardia- sympathetic stimulation with CHF
o +_ arrhythmia- APCs, atrial fibrillation (sometimes more problematic than the heart disease itself)
o Changes in complex morphology
o Look for complications- rhythm abnormalities are what will kill the dog, even if it has heart disease
What might be seen on blood tests in valvular disease?
Haematology
Anaemia, polycythaemia, WBC count
Biochemistry
Renal, liver disease, other systemic disease
Can do significant damage with the treatment that we use so monitoring biochemistry is important
Cardiac biomarkers
ANP, BNP, troponins
What are potential complications of valvular disease?
- ruptured chordae tendonae (emergency)
- intractable cough
- pulmonary hypertension
- pericardial effusion due to left atrial tear (after jet lesions)
- tussive syncope (syncope associated with coughing or occasionally with wretching/gagging)
Name some causes of pulmonary hypertension
- Alveolar hypoxia with pulmonary vasoconstriction/ remodelling (severe respiratory disease, e.g. IPF, neoplasia)
- Pulmonary vascular obstructive disease (e.g. pulmonary thromboembolism, heart worm)
- Pulmonary overcirculation
- High pulmonary venous pressure
- Idiopathic
Describe the presenting signs of endocarditis
Rarely present as a cardiac patient
Dogs> cats
Usually a sick patient with a variable murmur (can be diastolic if semilunar valve affected)
Other systemic signs are usually observed (e.g. variable pyrexia, shifting lameness, anorexia, lethargy, weight loss)
Describe how a continuous murmur due to endocarditis occurs
o Sounds like just a continuous noise- there are no obvious lubs and dubs
o The aortic valve becomes stenotic (systolic murmur) then the valve doesn’t close properly so also get a diastolic murmur
o Continuous rumbling
o Need to listen at base of heart or wouldn’t hear murmur
