Lecture 11 9/13/24 Flashcards
What is the most common acquired cardiac disease in dogs?
degenerative valvular disease/MVD
What is the primary importance of MVD?
important cause of morbidity and mortality in elderly small-breed dogs
What is the pathology of MVD?
-sterile degenerative process that affects the AV valves
-mucopolysaccharide found within spongiosa layer of the valve
-nodular thickening and distortion of valve leaflets
-chordae tendinae can lengthen and potentially rupture
What is the etiopathogenesis of MVD?
largely unknown, but there is a genetic predisposition
What is the pathophysiology of mitral valve disease?
-mitral valve regurg. results from valve leaflet distortion and lengthening/rupture of the chordae tendinae
-regurgitant volume augments pulmonary venous return
-regurg. imposes a volume load of left atrium and left ventricle
-progressive nature of MVD leads to further valve distortion and activation of RAAS which increased volume load of atrium and ventricle
-high atrial and pulmonary venous pressures can lead to CHF
-cough is most common presenting sign
-primary airway disease is common in patients with MVD
What are the characteristics of cardiac auscultation as it relates to MVD?
-systolic murmur heard over left apex
-murmur intensity is not consistently related to severity of MR
-soft MR murmurs are rarely of consequence but loud murmurs can be
What are the characteristics of pulmonary auscultation as it relates to MVD?
-increased bronchial tones
-crackles/wheezes
-crackles localize to small airways
How does a patient presenting for cardiac disease differ from a patient presenting for respiratory disease?
cardiac disease:
-thin body condition
-rapid heart rate
-regular rhythm unless pathologic arrhythmia is present
-loud murmur
resp. disease:
-obese body condition
-normal or slow heart rate
-exaggerated respiratory arrhythmia possible
-soft murmur
How is MVD diagnosed?
-chest rads to identify enlarged cardiac silhouette
-echo to identify left atrial and ventricular dilation
-echo to identify thick mitral leaflets/prolapse
When is echo required?
-cause of a cardiac murmur is uncertain
-difficult to tell if left atrium is enlarged with thoracic rads alone
-pulmonary arterial hypertension is suspected
-asymptomatic patients with murmurs grade 3/6 or louder with a VHS > 10.5
Why is furosemide/diuretic therapy used to treat MVD?
decrease in intravascular volume decreases venous pressure and facilitates clearance of edema
What are the characteristics of ACE inhibitor use in MVD treatment?
-value in dogs with subclinical MVD is uncertain, but thought to do no harm and potentially decrease mortality
-efficacious in the treatment of stage C MVD and DCM
Why is pimobendan used to treat MVD?
-increases sensitivity of contractile apparatus to available calcium
-has favorable effects on myocardial energetics
What is the EPIC inclusion criteria?
-grade 3/6 or louder murmur caused by MVD
-VHS > 10.5
-echo evidence of left atrial and left ventricular enlargement
What did the EPIC trial assess?
whether the administration of pimobendan delays the onset of pulmonary edema in subclinical canine MVD cases in which cardiomegaly has occurred
