Changes

* Prolapse of mitral valve leaflets into the left atrium during systole

* Prolapse of mitral valve leaflets into the left atrium during systole

* Tricuspid leaflets may also be affected, though usually not as severely as the mitral valve

* Tricuspid leaflets may also be affected, though usually not as severely as the mitral valve

* Doppler evidence of turbulent flow within the left atrium during systole

* Increased diastolic left ventricular diameter

* Fractional shortening may be increased. This is because in the setting of mitral regurgitation impedance to ventricular emptying is reduced (blood can be ejected into the low pressure left atrium)and end-diastolic ventricular stretch is increased by the addition of the regurgitant fraction, increasing the force of contraction. A reduced fractional shortening in the presence of DMVD indicates systolic dysfunction.

* Colour Doppler jet of mitral regurgitation

 

 

Thickening of the mitral valve leaflets is usually diffuse, but most pronounced at the leaflet edges. With myxomatous degeneration, the mitral valve becomes stiffer and distorted. The conformation of the valve remains constant throughout the cardiac cycle. Normally, the mitral valve leaflets do not extend beyond a line across the mitral annulus in systole. In dogs with DMVD, the mitral leaflets prolapse towards the left atrium during systole. Colour Doppler can be used to demonstrate the jet of mitral regurgitation. The size of the jet is related to the severity of mitral regurgitation. Most mitral regurgitation jets in DMVD are eccentric.

 

 

 

Fractional shortening may be increased (hyperynamic left ventricle). This is because, in the setting of mitral regurgitation, impedance to ventricular emptying is reduced (blood can be ejected into the low pressure left atrium)and end-diastolic ventricular stretch is increased by the addition of the regurgitant fraction, increasing the force of contraction.  

 

A serious complication of DMVD is chordae tendinae rupture, resulting in a 'flail leaflet' and acute worsening of mitral regurgitation. A leaflet segment typically 'flails' back into the left atrium during systole.

===Electrocardiogram (ECG)===

===Electrocardiogram (ECG)===