Mitral Valve Disease Flashcards
1
Q
Mitral Valve Disease
- Mitral stenosis
- Mitral regurgitation or insufficiency
- Combined valvular disease
A
- Mitral stenosis
- Abnormal thickening & restriciton in mitral valve leaflet motion
- Mitral regurgitation or insufficiency
- Abnormal retrograde flow across the valve
- Combined valvular disease
- Both mitral stenosis & mitral regurgitation or insufficiency
2
Q
Normal Mitral Valve
A
- Anterior & posterior leaflet
- Each divided into 3 segments
- Chordae tendinae
- Attach leaflets to the papillary muscles
- Valve commissures
- Junctions of the anterior & posterior leaflets w/ the valve annulus
- Cross sectional area
- 4-6 cm2
3
Q
Mitral Stenosis Etiologies
- Congential deformities
- Systemic diseases
- Pseudo-mitral stenosis
- Mitral annular calcification (MAC)
- Rheumatic valvular disease
A
- Congential deformities
- During infancy or child
- Systemic diseases
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Carcinoid syndrome
- Pseudo-mitral stenosis
- Mitral valve is anatomically normal
- Obstruction of transvalvular flow is caused by an extrinsic structure
- Cardiac tumor
- Most commonly atrial myxoma
- Large vegetations
- Physiological rather than anatomical restriction of mitral leaflet excursion
- Seen w/ severe aortic regurgitation
- Congenital atrial membranes
- Seen w/ cor triatriatum
- Cardiac tumor
- Mitral annular calcification (MAC)
- Calcificaiton of the annulus extends into the mtiral valve leaflets & restricts leaflet motion
- Rheumatic valvular disease
- Most common cause
4
Q
Rheumatic Valvular Disease
- Rheumatic mitral stenosis
- Rheumatic fever
- Most commonly involves…
- Mediated by…
A
- Rheumatic mitral stenosis
- Long-term sequelae of acute rehumatic fever
- Rheumatic fever
- Collagen vascular disorder that develops several weeks after a group A beta-hemolytic streptococcal infeciton (strep throat)
- Multi-systemic inflammatory condition
- Inflammatory changes –> damaged collagen fibers & ground substance in connective tissue
- Most commonly involves…
- The heart, joints, & CNS system
- Mediated by…
- The cross-reactivity of antibodies against streptococcal membrane proteins & human tissue
5
Q
Modified Jones Criterion
- Major criterion
- Minor criterion
- Diagnosis requirement
A
- Major criterion
- Carditis
- Myocarditis: inflammation fo the myocardium + ventricular dysfunction
- Pericarditis: inflammation of the pericardium + pericardial friction rub or effusion
- Valvulitis: inflammation of cardiac valves
- Polyarthritis
- Asymmetrical, migratory, polyarticular arthritis
- Chorea (Sydenham’s chorea, St. Vitus’s dance)
- Choreiform activity
- Rapid, uncoordinated, jerky movements of the face, hands, & feet
- Results from the destruction of cells in basal ganglia
- Revolves several months after the onset of acute rheumatic fever, but can persist indefinitely
- Subcutaneous nodules
- Small, painless, movable nodules
- Develop on the extensor surfaces of joints, spinous processes, & the occiput
- Erythema marginatum
- Evanescent, erythematous, nonpruritic macular rash w/ serpiginous margins & a clear center
- Carditis
- Minor criterion
- Arthralgia
- Diffiuse joint pain
- Fever
- Elevated ESR or cRP
- ESR: erythrocyte sedimentation rate
- cRP: C-reactive protein
- Serological markers of systemic inflammation
- ECG: increased PR-interval
- Arthralgia
- Diagnosis requirement
- 2 major criterion
- 1 major & 2 minor criterion
6
Q
Rheumatic Valvular Disease
- Acute phase
- Chronic phase
A
- Acute phase
- Valve leaflet inflammation –>
- Transient regurgitant murmurs
- Mid diastolic murmurs (Carey-Coombs murmur)
- Due to turbulent blood flow across inflamed valve leaflets
- Valve leaflet inflammation –>
- Chronic phase
- Progressive thickening & fibrosis of the mitral valve commissures, leaflets, & chordae
- Abnormal thickening & calcification of the valve leaflets
- Restricted leaflet excursion
- Thickening of the mitral subvavlular apparatus
- Leads to valvular stenosis or stenosis + regurgitation
- Diagnosed w/ cardiac ultrasound (echocardiography)
- Progressive thickening & fibrosis of the mitral valve commissures, leaflets, & chordae
7
Q
Hemodynamics of Mitral Stenosis
- Normal mitral valve (S1, a-wave, c-wave, v-wave)
- Mitral stenosis
A
- Normal mitral valve
- LV pressure > LA pressure in early systole –> mitral valve closes –> S1
- Mitral valve rebounds into the LA –> deflection in LA pressure tracing –> c-wave
- LA filling form the pulmonary venous return during ventricular systole –> increase in LA pressure –> v-wave
- LA pressure increases abov ethe descending portion of the LV pressure curve –> mitral valve opens (beginning of ventricular diastole) –> LA empties –> LA pressure falls
- LA contracts durign late diastole –> increase in LA pressure tracing –> a-wave
- Mitral stenosis
- Impaired leaflet excursion during diastole impedes LA emptying
- LA pressure increases to maintain transvalvular (LA to LV) flow
- Transvalvular gradient increases
- Magnitude of this gradient assesses mitral stenosis severity
8
Q
Impact of chronic elevation in LA pressures on the rest of the cardiopulmonary system
- Blood flow under normal conditions
- Mitral stenosis
- With ongoing passive congestion
- If left uncorrected
- Evolutionary standpoint
A
- Blood flow under normal conditions
- Superior & inferior vena cava –> RA –> tricuspid valve –> RV –> pulmonary artery –> pulmonary capillary bed –> pulmonary veins –> LA –> mitral valve –> LV –> systemic circulation
- LA & LV pressures are equal a the end of diastole when the mtiral valve is fully opened
- Mitral stenosis
- Impedance to LA emptying
- LA pressure increases to maintain antegrade flow across the stenotic valve
- Creates a pressure gradient b/n the LA & LV
- lLevation in LA pressure is passively transmitted back across the pulmonary vascular bed
- Post-capillary block: pulmonary hypertension via passive congestion
- With ongoing passive congestion
- Pre-capillary block: reactive vasoconstriction in pre-capillary beds
- Additional increases in pulmonary arterial & right heart pressures
- RV enlargement & dysfunction
- If left uncorrected
- Intimal hyperplasia, medial hypertrophy, & worsening pulmonary hypertension in the pulmonary vascular bed
- Evolutionary standpoint
- Increases in pre-capillayr pulmonary vascular resistance may be cardioprotective
- By preventing large surges in volume from the right heart into an engorged left sided system, pulmonary edema may decrease
9
Q
Symptoms associatd w/ mitral stenosis
A
- Symptoms related to mitral stenosis are categorized based on whether they’re primarily related to pre-capillary or post-capillary block
- Post-capillary block: pulmonary venous hypertension
- Pre-capillary block: pulmonary arterial hypertension
- Dyspnea & cough (post-capillary block))
- Pulmonary vascular congestion
- Pulmonary hypertension
- Orthopnea (post-capillary block)
- Positional increases in preload when –> supine
- Hemoptysis (post-capillary block)
- Spitting up of blood
- Chest pain
- RV hypertrophy
- Pulmonary hypertension
- Hoarseness (Ortner’s syndrome) (pre-capillary block)
- Compression fo the recurrent laryngeal nerve from a dilated pulmonary arter
- Peripheral edema
- Pulmonayr hypertension
- Right heart failure
- Chronic elevation in peripheral venous hydrostatic pressure
- Fatigue (pre-capillary block)
- Low output state
- Systemic thromboembolism
- Statis of blood flow in the LA –> thrombus formation in the LA appendage
10
Q
Auscultatory findings associated w/ mitral stenosis
A
- Normal mitral valve
- No significant LA to LV diastolic pressure gradient at end diastole
- Opening of the mitral valve is silent
- No diastolic murmur
- Mild mitral stenosis
- Elevated LA pressure –> LA to LV pressure gradient during early diastole
- Turbulent flow
- Diastolic rumble: low pitched diastolic murmur
- As LA to LV pressure gradient equilibrates toward mid diastole, rumble diminishes or disappears
- Pre-sytolic accentuation: rumble reappears in late diastole during atrial contraction
- Mitral stenosis increases in severity
- LA pressure continues to increase to a point where the LA to LV pressure gradient persists throughout diastole
- Holodiastolic rumble: diastolic rumble that persists throughout the diastolic filling period
- Assement of the severity of mitral stenosis
- Based on the timing of the closure of the aortic valve (S2) & onset of the mtiral valve opening snap
- As mitral vavle motion becomes more restricted
- Opening snap: early diastolic sound is generated as the valve reaches its elastic limits
- As LA pressure increases w/ worsening mitral stenosis, the LA pressure curve crosses the descending limb of the LV pressure curve earlier
- –> decreased A2 to Os interval
- As the mitral valve becomes more calcified & less pliable
- –> S1 becomes softer & more muffled
- As pulmonary hypertension develops
- –> P2 becomes louder
11
Q
Gorlin Formula
- Describes…
- Formula
- Mitral valve gradient increases with…
- Conditoins that increase CO
- Conditions that increase HR & decrease DFP
A
- Describes factors that can affect the mitral valve gradient in mitral stenosis
- √ΔP = CO / (MVA * DFP * 44.3)
- ΔP = mitral valve gradient
- MVA = mitral valve area
- CO = carida coutput
- DFP = diastolic filling period
- Mitral valve gradient increases with…
- Increased CO & HR (due to decreased diastolic filling time)
- Decreased MVA & DFP
- Conditions that increase CO
- Acute anemia, increased catecholamine tone, hyperthyroidism
- –> Increase in mitral valve gradient
- –> Asymptomatic patient w/ a fixed degree of mitral stenosis to become symptomatic
- Conditions that increase HR & decrease DFP
- Fever, rapid atrial fibrillation
- –> Increase in mitral valve gradient
12
Q
Medical Treatment of Mitral Stenosis
- Volume management
- Management
- Pregnancy
- Rate control
- Tachyarrhythmias
- Treatments
- Coexisting medical conditions
- Medical conditions
- Treatment
A
- Volume management
- Managed through regulation of oral fluid intake, dietary sodium restriction, & sometimes diuretics (ex. furosemide)
- Pregnancy: poorly tolerated in patients w/ significant mitral stenosis
- Due to increased intravascular volume & cardiac output in the 2nd & 3rd trimesters
- Rate control
- Tachyarrhythmias (ex. atrial fibrillation) are often poorly tolerated in patients w/ significant mitral stenosis
- Due to decreased diastolic filling period & loss of augmentation of late diastolif flow w/ loss of “atrial kick”
- Treatments: adequate rate control & sinus rhythm restoration (when possible)
- Tachyarrhythmias (ex. atrial fibrillation) are often poorly tolerated in patients w/ significant mitral stenosis
- Coexisting medical conditions
- Medical conditions –> increased transvalvular flow –> increased cardiac output –> clinical decompensation in patients w/ mitral stenosis
- Ex. hyperthyroidism, acute infection w/ fever, Paget’s disease, & arteriovenous malformations
- Treatment: manage co-morbid conditions
- Medical conditions –> increased transvalvular flow –> increased cardiac output –> clinical decompensation in patients w/ mitral stenosis
13
Q
Surgical Treatment of Mitral Stenosis
- Percutaneous balloon valvuloplasty
- Procedure
- Scoring systems
- Ideal candidates
- Mitral valve commissurotomy
- Mitral valve replacement
A
- Percutaneous balloon valvuloplasty
- Procedure
- Interarterial septum is punctured using a small needle tipped catheter
- Balloon tipped catheter is passed across the interatrial septum from the RA to the LA
- Balloon is advanced across the mitral valve & inflated to increase the mitral valve area
- Scoring systems
- Echos assess mitral valve thickness, leaflet mobility & calcification, & subchordal thickening
- Ideal candidates
- Younger, low valvuloplasty scores, no prior history of surgical commissurotomy, no significant mitral regurgitation
- Procedure
- Mitral valve commissurotomy
- In patients who aren’t candidates for balloon valvuloplasty
- Surgically separate the mitral valve leaflets in regions of commissural fusion
- On or off bypass
- Mitral valve replacement
- In patients who aren’t candidates for balloon valvuloplasty
- W/ either a mechancial (metallic) or bioprosthetic (porcine or bovine) valve
14
Q
Mitral Regurgitation Etiologies
A
- Mitral valve prolapse
- Imperfect coaptation of myxomatous mtiral leaflets
- Rheumatic valvular disease
- Fibrosis & tethreingof valve leaflets
- Endocarditis
- Leaflet inflammation
- Obstruction of leaflet coaptation by large vegetations
- Leaflet destruction in the form of flail leaflets, leaflet perforation, &/or perivalvular abscesses
- Dilated cardiomyopathy
- Dilation of the mitral valve annulus
- Apical displacement of the mitral leaflet coaptation point due to enlargement of the ventricular cavity
- Coronary ischemia (rare)
- Ischemically mediated paipllary muscle dysfunction
- Infarction: papillary muscle rupture from myocardial necrosis
- Trauma (rare)
- Rupture of papillary muscles & chordae tendinae
- Systemic diseases (rare)
- Carcinoid syndrome
- Collagen vascular disease which can cause fibrosis & deformity of the mitral valve
15
Q
Pathophysiology of Mitral Regurgitation
- Aorta & LA in mitral regurgitation
- Results of reducing impedance to LV emptying
- Although total LV SV increases…
A
- Aorta & LA in mitral regurgitation
- Aorta & LA function as parallel circuits durign ventricular systole
- LA is at lower pressure at baseline –> impedance to LV emptying is reduced
- Results of reducing impedance to LV emptying
- Decrease LV end systolic pressure
- Decrease LV systolic radius
- Decrease LV wall tension (Laplace’s Law)
- Increase magnitude & velocity of myofibril shortening
- Although total LV SV increases…
- Forward flow across the aortic valve decreases
- Retrograde flow from the LV to the LA increases
- –> increase in LA pressure
- Magnitude of this pressure increase is determined by regurgitant volume, LA compliance, & intravascular volume