MITRAL REGURGITATION

I. Pathophysiology:

• Abnormal LA pressure increase during ventricular systole, so abnormally high 'v' wave
• LV is filled rapidly from a higher starting LA pressure so more abrupt 'y' descent
• Usually some left atrial enlargement
• Usually some increase in LVEDP
• Compensation: LV hypertrophies and dilates to make EDV sufficient to maintain SV

II. Clinical presentation:

• Similar symptomatology as MS but different compensations
• CHF develops over years, unless MR is sudden in onset
• Heart Sounds: see under "Cardiac Murmurs"

III. Mnemonic for causes of MR: "PRIESTS' CAPS"

P apillary musc. problems (rupture or fibrosis, 2? to ischemia, LV dilatation, bact. endocarditis)

R heumatic HD (40% of cases of MR, more common result of RHD in males; females get more MS)

I HSS (on echo, see ant. motion of the mitral valve during systole)

E ndocarditis, infective (due to direct involv. of valve or chorae tendinae; also Endocardial cushion defects)

S LE & other collagen-vast. disorders, esp. RA (not so common)

T ransposition of the great vessels, corrected

S pondylitis, ankylosing (3% of pts get MR; same amount get AR)

C alcified mitral annulus (us. in elderly, causes very MILD MR)

A neurysm of LV (changes pap. mm. configuration)

P rolapse of mitral valve (us. very MILD MR, but increased incidence of endocarditis and arrhythmias)

S ingle papillary m. (congenital, aka "parachute mitral valve"; valve may be regurgitant, stenotic, or neither)

IV. Treatment

• Mitral valve repair
• Mitral valve replacement (bioprosthetic or mechanical)
• In a nonrandomized prospective study of 1250 patients undergoing surgery for mital regurgitation, repair was ass'd with high overall 10-year survival than replacement (62% vs. 46%); this survival advantage was limited to patients < 60yo at surgery (Circ. 108:298, 2003--abst)
• In a prospective study in 132 pts with severe MR but no sx and normal LV function who underwent surgical repair only if they developed sx or LV dysfunction (or pulmonary HTN or recurrent AF), 8y survival was 91%; similar to that expected in the general population (Circ. 113:2238, 2006--JW)