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Mitral Valve Disease
Mitral Valve Disease Lecture
| Question | Answer |
|---|---|
| Mitral Stenosis | Abnormal thickening and restriction in mitral valve leaflet motion |
| Mitral regurgitation or insufficiency | Abnormal retrograde flow across the valve |
| Combined valvular disease | both mitral stenosis and regurgitation |
| What are the 3 basic forms of mitral valve disease? | stenosis, regurgitation/insufficiency, combined valvular disease (both of the above) |
| Describe the structure of the normal mitral valve | 2 leaflets (anterior and posterior), each divided into 3 segments. Each leaflet attached to papillary muscles by chordae tendinae; the junction between anterior and posterior leaflets with the valve annulus referred to as the commissures |
| What are the possible etiologies for mitral stenosis? | congenital deformities, rheumatic valvular disease, dense mitral annular calcification, systemic disease (lupus, rheumatoid arthritis, carcinoid syndrome, etc), pseudo mitral stenosis |
| What is the most common cause of mitral stenosis? | Rheumatic valvular disease |
| How does mitral annular calcification lead to stenosis? | Calcification extends from the annulus to the leaflets, restricts leaflet motion |
| What is pseudo mitral stenosis? | Mitral valve anatomically normal. Obstruction casued by extrinsic structure |
| How does rheumatic mitral stenosis arise? | Long term sequelae from acute rheumatic fever |
| Rheumatic fever | collagen vascular disorder which occurs following group A beta hemolytic streptococcal infections (strep throat); develops after several weeks after acute strep infection; involves joints, heart, CNS |
| What histological changes are seen rheyumatic fever? | inflammation --> damage of collagen fibers + ground substance in connective tissue; thought to be mediated by cross reactivity of Ab against streptococcal membrane proteins and human tissue |
| How is rheumatic fever diagnosed? | Modified jones Criterion (2 major criteria or 1 major and 2 minor criteria) |
| What are the major criteria in the modified jones criteion for the diagnosis of acute rheumatic fever | carditis, polyarthritis, chorea, subcutaneous nodules, erythema margitanum |
| What are the minor criteria in the modified jones criteion for the diagnosis of acute rheumatic fever | Arthralgia, fever, elevated ESR (erythrocyte sedimentation rate) or cRP (C-reactive protein), ECG: increased PR interval) |
| In rheumatic fever, how does carditis present? | Can be myocarditis (inflammation of myocardium with ventricular dysfunction), pericarditis (inflammation of the pericardium with pericardial friction rub or effusion), or valvulitis (inflammation of the cardiac valves) |
| In rheumatic fever, how does polyarthritis present? | Asymmetrical, migratory, polyarticular arthritis |
| In rheumatic fever, how does chorea present? | Syndeham's chorea (aka St. Vitus's dance): choreiform activity with rapid uncoordinated, jerky movement of cae, hands, feet; thought to be caused by destruction of basal ganglions; resolves after several months of onset but may persist indefinitely |
| In rheumatic fever, how does sybcutaenous nodules present? | Usually 0.5-2 cm movable, firm painless nodules which develop on extensor surfaces of joints, spinous processess and occiput |
| In rheumatic fever, how does erythema marginatum present? | Evanescent (fading), erythematous (red), nonpruritic macular rash with serpinginous (creeping, wormlike) margins and clear center |
| Describe the changes in the heart + blood during the acute phase of rheumatic fever | valve leaflet inflammation --> transient regurgitant murmurs and mid-diastolic murmurs (aka Carey-Coombs murmur) due to turbulent blood flow |
| Describe the changes in the heart + blood during the chronic phase of rheumatic fever | progressive thickening + fibrosis of the mitral valve commissures, leaflets, and chordae leading to stenosis or a combination of stenosis and regurgitation |
| What would you expect to find on an echocardiograph of a patient with chronic rheumatic valvular disease? | Abnormal thickening and calcification of the valve leaflets with restriction in leaflet excursion and thickening of the mitral subvalvular apparatus. |
| What event casues the c-wave? | Mitral valve rebounds upon systole and deflects into left atrium, causing a deflection in the left atrial pressure tracing |
| What event is associated with the v-wave? | Mitral valve reamins closed during systole-->as it fills (due to pulmonary venous inflow), pressure progressively rises |
| What even is responsible for the a-wave? | Towards END of ventricular diastole, left atrial contraction occurs, creating a transient increase in lef-atrial pressure tracing |
| What hemodynamic changes do you see in patients with Mitral Stenosis? | Transvalvular pressure gradient rises (due to decreased atrial outflow into ventricle) |
| What are the hemodynamic changes associated with chronic elevation in left aterial pressure on the rest of the cardiopulmonary system? | Left atrium can't empty as well, and left atrial pressure rises to maintain forward flow to LV; Increased LA pressure --> pulmonary + RV hypertension + congestion-->reactive vasoconstriction in pre-capillary beds of lungs --> more RV enlargement |
| What symptoms do patients with mitral stenosis develop? | Dyspnea and cough, orthopnea, chest pain, hoarseness, peripheral edema, fatigue, systemic thromboembolism |
| What symptoms of mitral stenosis develop as a result of pre-capillary block? | Low CO: fatigue, exhaustion, weakness, tiredness; right sided failure edamn, hepatomegally, tricuspid insufficiency, cyanosis, large heart, mild jaundice, hoarseness |
| What symptoms of mitral stenosis develop as a result of post-capillary block? | Dyspnea, orthopnea, pulmonary edema, hemoptysis, cough, left sided failure, small heart, pulmonary congestion, no edema |
| What auscoltatory findings would you find in patients with mitral stenosis? | Mild: decresendo diastolic rumble (due to turbulence) with possible pre-systolic accentuation (due to atrial contraction); moderate: pan-diastolic rumble; progressive decrease in A2 to opening snap interval (OS not normally heard); soft S1, louder P2 |
| What is the Gorlin formula? | Square root (mitral valve pressure gradient) = (Cardiac Ouput) / (Mitral valve area * diastolic filling period * 44.3) |
| What conditions can lead to increased mitral valve gradients? | Conditions that increased CO, higher heart rates (decrease diastolic filling period), increased catecholamine tone, and hyperthyroidism |
| How is mitral stenosis treated? | Medical: volume management, rate control, and controlling coexisting medical conidtions. Surgical: percutaneous baloon valuloplasty, mitral valve commisurotomy, mitral valve replacement |
| Volume management of mitral stenosis | Regulate oral fluid intake, restrict Na consumption; oral diuretics (furosemid); important in pregant women (increase in intravascular volume + CO) |
| Rate control management of mitral stenosis | Rate control and (when possible) restoration of sinus rhythm; IMPORTANT for patients with tachyarrhytmias due to decrease in diastolic filling period and loss of atrial kick-->insufficient CO |
| How does percutaneous baloon valvuloplasty work? | insert catheter into right atrium through venous sheath-->intratrial septum punctured using small needled catheter --> balloon on catheter advanced through to mitral valve area and inflated to increase area |
| Who are ideal candidates for balloon mitral valvuloplasty? | younger patients with low valvuloplasty scores, no prior history of surgical commissurotomy, and no significant mitral regurgitation; provides good results (event free 5-7 years post procedure) |
| Mitral valve commissurotomy | surgically separating mitral valve leaflets in regions of commissural fusion; done either on or off bypass |
| Mitral valve replacement | With either mechanical (metallic) or bioprosthetic (porcine or bovine)valve |
| What are the etiologies for mitral valve regurgitation? | Mitral valve prolapse, rheumatic valvular disease, endocarditis, dilated cardiomyopathy, cornoary ischemia, trauma, systemic diseases |
| How can mitral valve prolapse lead to mitral regurgitation? | imperfect coaptation of the mitral leaflets |
| How can rheumatic valvular disease lead to mitral regurgitation? | Fibrosis and tethering of the valve leaflets |
| How can endocarditis lead to mitral regurgitation? | leaflet inflammation, obstruction of leaflet coaptation by large vegetations, or leaflet destruction in the form of flail leaflets, leaflet perforation and/or perivalvular abcessess |
| How can dilated cardiomyopathy lead to mitral regurgitation? | dilation of the mitral valve annulus and/or apical displacement of the mitral leaflet coatpation poin due to enlargement of the ventricular cavity |
| How can coronary ischemia lead to mitral regurgitation? | due to ischemically mediated papillary muscle dysfunction or (in infarction) papillary muscle rupture related to myocardial necrosis |
| How can trauma lead to mitral regurgitation? | rupture of the papillary muscles |
| How can systemic disease lead to mitral regurgitation? | Possible causes: carcinoid syndrome and collagen vascular diseases (cause fibrosis and deformity of the mitral valve) |
| Pathophysiology of acute Mitral Regurgitation | Increased LV stroke Volume (with decrease forward flow and increased backward flow) --> increased LA pressure and increased pulmonary venous pressure (may cause pulmonary edema) |
| What changes do you expect to see in the left atrium with mitral regurgitation? | Decrease LV end-systolic pressure, decreased LV systolic radius, decreased wall tension (Laplace's law), and increased extend and velocity of myofibril shortening |
| What changes are seen in pathophysiology of chronic MR? | Left ventricular and atrial remodeling can occur to compensate --> eccentric ventricular hypertrophy --> increase in left ventricular volume; increased LV diastolic wall stress -->eccentric hypertrophy and left ventricular enlargement-->worse MR |
| What is the change you expect to see in the left-ventricular pressure-volume relationship in acute mitral regurgigration? | insufficient time for remodeling --> compliance remains same --> left ventrcile responds to shift in loading conditions by shifting along FIXED pressure volume curve; if shift large enough --> pulmonary edema |
| What is the change you expect to see in the left-ventricular pressure-volume relationship in subacute mitral regurgigration? | Rises less dramatically --> ventricular remodeling through eccentric hypertrophy --> increase in LV volume and compliance --> shifts patient to new left ventricular pressure-volume relationship --> chornic compensated phase of mitral regurgitation |
| What is the change you expect to see in the left-ventricular pressure-volume relationship in chronic mitral regurgigration? | Left ventricle becomes increaseing dysfunctional during systole --> LV pressure rises --> congestive heart failure and CHRONIC DECOMPENSATED PHASE of mitral regurg. |
| What changes would you see in the atrial pressure curves in patients with mitral regurgitation? | Prominent V-waves (simultaneous filling of LA from lung and contracting LV); rapid y-descent due to augmented antegrade flow (due to increased atrial preload) |
| What auscultatory findings would you find in patients with significant mitral regurgitation? | Best heard in 5th intercostal space in anteroaxillary line + radiation into axilla: Pan-or holosystolic murmur (S1-->slightly beyond A2), early dystolic rumble (with possible S3); murmur location can vary based on direction of jet |
| What is the cause of mitral valve prolapse? | Myxomatous degeneration of mitral valve with redundant leflets that are inappropriately elongated relative to ventricular diameter |
| What happens during mitral valve prolapse? | Ventricle contracts --> redundant mitral valve leaflets bow/prolapse into atria --> inappropriate coaptation of leaflet tips |
| What auscultatory finding would you find in mitral valve prolapse? | mid-to-late systolic click as the leaflets tense during prolapse; if leaflets don't coapt well-->mid-to-late systolic regurgitatn murur following systolic click |
| How does the position of the mitral valve click change with systole? | Increasing left ventricular volume --> mitral valve click and murmur later in systole |
| How is mitral regurgitation treated? | Relieve pulmonary vascular congestion (DIURETICS); reduce peripheral vascular resistance to augment forward blood flow (VASODILATORS or if critically ill, SODIUM NITROPUSSIDE); intra-aortic balloon; surgical repair or replacement of mitral valve |
| How does an intra-aortic baloon pump work and why does it help patients in cardiogenic shock? | Percutaneous catheter based therapy; during diastole, IABP inflates, displacing blood in descending thoracic aorta in retrograde and antegrade direction, improving coronary perfusion; deflates in systole to facilitate foward flow |
| What is the definitive treatment for patients with mitral regurgitation? | Surgical repair or replacement of mitral valve |
| What is the mechanism of action of sodium nitroprusside? | Potent arteriolar vasodilator: metabolized into NO --> guanylate cyclase activation in vascular smooth muscle cells --> stimulates cGMP production, which promotes calcium reuptake from cytoplasm into endoplasmic reticulum --> smooth muscle relaxation |
| What are the advatages and disadvantages of using nitroprusside? | Pro: short half-life, easily titrated; Con: cyanide is metabolic byproduct, so monitor CN if used over long period of time |
| Medical management of chronic mitral regurgitation focuses on: | 1) diuretics to manage volume overload and 2) vasodilator therapy in patients with systemic hypertension (no definitive data on benefit of chronic vasodilator therapy in normotensive patients) |
| What are the surgical treatment options for patients with mitral valve prolapse? | Mitral valve replacement (mechanical or bioprostetic); Mitral valve repair (avoids need for long term anticoagulation and minimiszed amount of prosthetic material implanted) |
| How is post-operative survival affected by LV ejection fraction? | Postoperative survival decreases as LV function decreases. |
| When should a patient be recommended for mitral valve surgery? | Rule of thumb: mitral valve surgery for patients with severe regurgitation PRIOR to patient developing significant symptoms or left ventricular dysfunction |
Created by:
karkis77
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