Mitral Regurgitation

Abnormalities of the Mitral Valve Valve Leaflets Chordae Tendineae Papillary Muscles Mitral Annulus

Abnormalities of the Valve Leaflets Rheumatic Heart Disease –shortening, rigidity, deformity and retraction of the leaflets Infective Endocarditis –perforation, retraction(healing), and prevention of coaptation

Abnormalities of the Mitral Annulus Dilation –normally the mitral annulus constricts during systole. A dilated left ventricle will result in dilation of the mitral annulus and result in mitral regurgitation.

Abnormalities of the Mitral Annulus Calcification –one of the most common cardiac abnormalities found at autopsy. Usually of little consequence but may immobilize the basal portions of the MV leaflets preventing their normal excursion.

Abnormalities of the Chordae Tendineae Rupture –primary –infective endocarditis –trauma –rheumatic fever Lenghtening of the chordal structures may occur with MV prolapse allowing excessive billowing of the MV leaflets

Abnormalities of the Papillary Muscles Myocardial ischemia can cause a spectrum of problems for the papillary muscles –papillary muscle dysfunction –papillary muscle necrosis –papillary muscle rupture

Pathophysiology The left ventricle has two systems it dumps into - the LA and the aorta, so MR enhances LV emptying The LA is a low pressure system therefore it is easier for blood to be ejected into the LA than the aorta

Pathophysiology The amount of blood ejected into the the LA depends on a number of factors –impedence of LV emptying into the systemic circulation –LV size itself, a larger LV will stretch the mitral annulus and cause further regurgitation

Pathophysiology The amount of blood ejected into the LA depends also on the reverse pressure gradient between the LA and the LV –chronic MR will result in enlargement of the LA and lower LA pressure –in acute MR the LA is small and non-compliant so pressures are higher

History Symptoms from MR usually does not develop until the left ventricle begins to fail. When symptoms do develop they are related to LV failure - dyspnea on exertion, easy fatigability, decreased exercise tolerance, orthopnea, and paroxysmal nocturnal dyspnea. The development of LV failure is a poor prognostic sign. Sudden onset of symptoms should alert the examiner of complications such as ruptured chordae, endocarditis, ruptured papillary muscle.

Physical Examination Palpation - the PMI is displaced laterally and downward. Arterial pulse - since AS and MR are both systolic murmurs one way to differentiate the two is to check the arterial pulse. Remember the carotid pulse in AS is delayed and depressed, it is sharp and on time in MR.

Physical Examination Auscultation –S1 is usually diminished in intensity and may be obscured by the murmur –S2 may also be obscured for the same reason and there may be wide splitting since LV emptying is more rapid S1 A2P2

Physical Examination Auscultation continued –S3 (early filling) is usually audible with significant MR due to an abnormally large and rapid inflow of blood into the left ventricle during the rapid filling phase in early diastole. MV Opens Atrial Contraction Begins MV Closes Passive Filling Active Filling S3 S4

Physical Examination The Murmur –A systolic murmur that is usually long and loud and heard best at the apex throughout systole. Known as a holosystolic murmur. –May radiate out to the axillary line on the chest, and sometimes can be heard throughout the chest –The intensity of the murmur and the severity of the MR does not usually correlate.

Physical Examination The Murmur described as a blowing or high pitched murmur S1 S2 Mitral Regurgitation

Physical Examination Dynamic Auscultation –Any maneuver that results in an increase in systemic resistance will result in a louder murmur and vice versa. handgrip, squatting = louder murmur amyl nitrite = softer murmur –Any maneuver that results in a decrease in venous return will result in a softer murmur and vice versa. Standing, initial phase of valsalva = softer murmur squatting = louder murmur

Chest X-Ray

EKG

Echocardiography

Echocardiography Chordal Rupture

Echocardiography Perforation from Endocarditis

Cardiac Catheterization

Medical Management of Mitral Regurgitation Afterload Reduction Digoxin –CHF –Control of arrhythmias Diuretics Ab for SBE prophylaxis

Surgical Management of Mitral Regurgitation Indications –Factors influencing timing of surgery for MR include symptoms, LV ejection fraction, LV ESD, atrial fibrillation and pulmonary HTN. –Acute symptomatic MR –Patients who are functional class II, III, IV with normal LV function (ejection fraction >60%) –Symptomatic or asymptomatic patients with mild LV dysfunction EF 50-60% – Symptomatic or asymptomatic patients with moderate LV dysfunction EF 30-50%

Surgical Management of Mitral Regurgitation In most cases, mitral valve repair is the operation of choice for those with suitable valvular anatomy. –Annuloplasty with the use of a ring prosthesis –reconstruction of the valve leaflets –replacement, reimplantation, elongation, or shortening of the chordae or papillary muscles

Surgical Management of Mitral Regurgitation Mitral Valve Replacement –This can be accomplished with either a bioprosthesis or a mechanical prosthesis

Surgical Management of Mitral Regurgitation

Valve replacement can be associated with some further impairment of LV function due to loss of chordal-papillary continuity which interferes with left ventricular function Bioprosthesis can wear out Mechanical prosthesis can be associated with thromboembolism