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Small animal cardiac ultrasound measurements

LA:Ao (Left atrium:aortic root ratio)

Right parasternal short axis view at the level of left atrium and aorta (‘Mercedes Benz’)
Measurement on frozen B-mode image
Measurement taken during diastole (just before QRS on ECG)
Measurements taken: LA Diam + Ao Diam (machine will calculate LA:Ao for you)
Lines should be drawn through middle of aortic valve leaflets and continued through left atrium in a straight line
Normal value - <1.5 in normal dog
Increased value in left atrial enlargement (disease like Mitral regurgitation)



FS (Fractional shortening)
Right parasternal short axis view at level of chordae tendinae (Mushroom view)
Measurement on frozen M-mode image
3 measurements taken during diastole and 3 during systole (6 total)
Diastole (just before QRS on ECG)
- IVSd (Interventricular septum at end diastole)
- LVIDd (Left ventricular internal diameter at end diastole)
- LVPWd (Left ventricular posterior wall thickness at end diastole) or LVFWd 
 (Left ventricular free wall thickness at end diastole) – depends on if human machine Systole (at nadir of septal motion – when ventricular diameter narrowest)
- IVSs (Interventricular septum at end systole)
- LVIDs (Left ventricular internal diameter at end systole)
- LVPWs (Left ventricular posterior wall thickness at end systole) or LVFWs 
 (Left ventricular free wall thickness at end systole) – depends on if human machine
All measurements are taken from leading edge to leading edge (see below)
Machine will calculate Fractional shortening
Normal value - >25% in normal dog (breed variations!)
Decreased in DCM (heart contracting poorly during systole)



EF (Ejection fraction)
Right parasternal long axis view (4 chamber view)
Measurement on frozen B-mode image
Simpson’s rule used to evaluate left ventricular volume 
2 measurements made during diastole and 2 measurements taken during systole
Diastole
- LVLd (Left ventricle length during diastole)
- LVAd (Left ventricle area during diastole)
Systole
- LVLs (Left ventricle length during systole)
- LVAs (Left ventricle area during systole)
Machine will calculate Ejection fraction (will also display EDV and ESV – End diastolic 
volume and End systolic volume)
Normal value - >50% in normal dog
Decreased in DCM (heart contracting poorly during systole)



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