Mitral Regurgitation

MR is caused by:

Abnormalities of any part of the MV (leaflets, annulus, chordae, papillary muscles) or as a result of left sided heart dysfunction

What is primary MR?

An abnormality with a component of the MV itself

What is secondary (functional) MR?

MR results from other cardiac disease (CAD or cardiomyopathy) but the MV is structurally normal

What causes primary MR?

Age related degeneration, rheumatic heart disease, infective endocarditis, trauma, congenital MV malformations, MAC, connective tissue disorders causing prolapse

When in the cardiac cycle does MVP occur?

Systole

Triangular shaped MR CW jet indicates

Severe regurgitation

Causes of secondary (functional) MR:

CAD, MI, dilated cardiomyopathy, HCM, AFib

What is acute MR:

Results in sudden volume and pressure overload in the LA, leading to increased LAP. LV volume overload occurs so LVEDP increases.

Acute MR causes:

Increased preload, increased HR, increased SV, hyperdynamic LV

Decreased CO, hypotension, cardiogenic shock.

What causes acute MR?

Endocarditis, papillary muscle rupture (from acute MI), rupture of chordae

What does Doppler jet look like for acute MR?

Low velocity jet from shock. Creates a high inflow velocity waveform (above baseline) and triangular MR jet.

What does chronic MR cause?

Causes gradual volume and pressure overload leading too dilation of LA and LV.

Increased SV to handle increased preload

Ultimately, leads to PHTN, pulmonary edema and systolic HF

How to tell the difference between acute and chronic MR

Acute: normal EF and normal size LV

Chronic: EF is normal, LV enlarged (once becomes significantly enlarged then EF begins to drop) (called decompensated MR)

Symptoms of MR:

Symptoms are related to rate of progression, PAP, arrhythmias, associated cardiac disease.

Occur late in pts with primary MR

Transition from asymptomatic to symptomatic is important for timing of intervention

Primary MR: DOE, fatigue, PHTN, new Afib

Severe MR: symptomatic HF, pulmonary congestion, edema, at this stage systolic dysfunction is irreversible

Chronic secondary MR: mild symtoms and they usually reflect ventricular dysfunction more than the MR. Reflect decreased CO: weakness, fatigue, exercise intolerance

MR murmur:

Holosystolic high pitched blowing murmur

MVP murmur:

Midsystolic click

A vena contracta of >7mm is what grade of MR?

Severe

A vena contracta <3mm is what grade of MR?

Mild

PISA radius should be measure when in cardiac cycle?

Systole

PISA EROA of >0.4cm² is what grade of MR?

Severe

A PISA EROA of 0.2cm² is what grade of MR?

Mild

A regurgitant volume of 60mL/beat is what grade of MR?

Severe

A regurgitant volume of <30mL/beat is what grade of MR?

Mild

How does pulmonary vein reversal occur?

During systole the MV should be closed and blood flows from the Pulm veins into the LA. With severe MR the LA is filling with retrograde flow during systole through the MV, increasing LAP and causing flow to reverse into the pulmonary veins.

What does a systolic flow reversal in pulmonary veins look like?

S wave below baseline, D wave above baseline, and A wave below baseline. (S wave should be above baseline with D wave.)

Blunted flow= smaller S wave above baseline

Echo findings with MR

Increased LAP (higher E wave velocity), systolic reversal in pulm veins (only in severe MR), increased PAP (always with severe MR, may or may not be with moderate MR)

Repair options for MR:

Valvuloplasty and annuloplasty band or mitraclip

What conditions don’t favor repair?

Severely calcified valves & annulus, some cases of rheumatic MV, signifant tissue destruction from endocarditis.

In these cases, MV replacement may be favorable.