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Flashcards in Mitral Valve Disease Deck (23):
1

Mitral Valve Disease

  • Mitral stenosis
  • Mitral regurgitation or insufficiency
  • Combined valvular disease

  • 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

Normal Mitral Valve

  • 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

Mitral Stenosis Etiologies

  • Congential deformities
  • Systemic diseases
  • Pseudo-mitral stenosis
  • Mitral annular calcification (MAC)
  • Rheumatic valvular disease

  • 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
  • Mitral annular calcification (MAC)
    • Calcificaiton of the annulus extends into the mtiral valve leaflets & restricts leaflet motion
  • Rheumatic valvular disease
    • Most common cause

4

Rheumatic Valvular Disease

  • Rheumatic mitral stenosis
  • Rheumatic fever
  • Most commonly involves...
  • Mediated by...

  • 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

Modified Jones Criterion

  • Major criterion
  • Minor criterion
  • Diagnosis requirement

  • 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
  • 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
  • Diagnosis requirement
    • 2 major criterion
    • 1 major & 2 minor criterion

6

Rheumatic Valvular Disease

  • Acute phase
  • Chronic phase

  • Acute phase
    • Valve leaflet inflammation -->
      • Transient regurgitant murmurs
      • Mid diastolic murmurs (Carey-Coombs murmur)
    • Due to turbulent blood flow across inflamed valve leaflets
  • 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)

7

Hemodynamics of Mitral Stenosis

  • Normal mitral valve (S1, a-wave, c-wave, v-wave)
  • Mitral stenosis

  • 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

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

  • 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

Symptoms associatd w/ mitral stenosis

  • 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

Auscultatory findings associated w/ mitral stenosis

  • 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

Gorlin Formula

  • Describes...
  • Formula
  • Mitral valve gradient increases with...
  • Conditoins that increase CO
  • Conditions that increase HR & decrease DFP

  • 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

Medical Treatment of Mitral Stenosis

  • Volume management
    • Management
    • Pregnancy
  • Rate control
    • Tachyarrhythmias
    • Treatments
  • Coexisting medical conditions
    • Medical conditions
    • Treatment

  • 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)
  • 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

13

Surgical Treatment of Mitral Stenosis

  • Percutaneous balloon valvuloplasty
    • Procedure
    • Scoring systems
    • Ideal candidates
  • Mitral valve commissurotomy
  • Mitral valve replacement

  • 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
  • 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

Mitral Regurgitation Etiologies

  • 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

Pathophysiology of Mitral Regurgitation

  • Aorta & LA in mitral regurgitation
  • Results of reducing impedance to LV emptying
  • Although total LV SV increases...

  • 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

16

Pathophysiology of Acute & Chronic Mitral Regurgitation

  • Acute mitral regurgitation
    • LA complicance
    • Increase reguritant volume -->
  • Chronic mitral regurgitation
    • Chronic volume overload -->
    • Chronic LV diastolic volume overload -->
    • Chronic LA volume overload -->
    • Symptoms

  • Acute mitral regurgitation
    • LA complicance is fixed
    • Increase regurgitant volume --> increase LA pressure & pulmonary capillary wedge pressure --> pulmonray edema
  • Chronic mitral regurgitation
    • Chronic volume overload --> LV & LA remodeling
    • Chronic LV diastolic volume overload --> eccentric hypertrophy of ventricular myocytes --> increase LV cavity size
      • --> maintain normal forward SV despite valvular regurgitation
      • --> increase LV diastolic wall stress --> ongoing eccentric hypertrophy --> progressive LV enlargement & mitral annular dilation --> increase mitral regurgitation
    • Chronic LA volume overload --> gradual LA enlargement --> increase LA compliance --> LA can accommodate larger regurgitant volumes w/ less elevation in atrial pressure than w/ acute mitral regurgitation
    • Patients have a long latent period before becoming symptomatic

17

Impact of Acute & Chronic Mitral Regurgitation on the Left Ventricular Pressure-Volume Relationships

  • Acute severe mitral regurgitation
    • Compensatory changes
    • LVEDP shifts
  • Chronic mitral regurgitation
    • LV pressure
    • Chronic compensated phase

  • Acute severe mitral regurgitation
    • Insufficient time for compensatory changes in LA & LV compliance
      • Changes in LA & LV volumes --> increased chamber pressure
    • LVEDP shifts
      • Large increases in LV volume --> large increases in LVEDP --> pulmonary edema
  • Chronic mitral regurgitation
    • LV pressure rises abruptly
      • Chronic increases in LV end diastolic wall stress --> eccentric hypertrophy --> increased LV volume & compliance
    • Chronic compensated phase
      • LV systolic dysfunction --> increase ventricular pressure --> congestive heart failure --> chronic decompensated phase

18

Hemodynamic Findings with Mitral Regurgitation

  • Simultaneous antegrade & retrograde filling of the LA from pulmonary venous inflow & mitral regurgitation --> prominent v-waves
  • Increased LA to LV pressure gradient --> rapid antegrade flow across the mitral valve --> rapid y-descent

19

Auscultatory Findings with Severe Mitral Regurgitation

  • Pan- or Holo-systolic murmur
    • Due to regurgitatnt flow from the LV to the LA
    • Murmur begins w/ closure of the mitral valve (S1) & persists throughout systole
    • B/c the mitral valve opens slightly after the aortic valve closure at the dicrotic notch (S2)
      • Regurgitant murmur can persist slightly beyond A2
  • Early diastolic rumble
    • Due to increased LA pressure --> turbulent antegrade flow across the mitral valve
  • S3
    • Due to rapid diastolic inflow into the LV
  • Best heard in the 5th intercostal space in the anteroaxillary line
    • Radiates to the axilla

20

Mitral Valve Prolapse

  • Common cause of...
  • Myxomatous degeneration
  • Auscultatory findings
  • Maneuvers that...
    • Decrease LV volume -->
    • Increase LV volume -->

  • Common cause of mitral regurgitation
  • Myxomatous degeneration
    • Degeneration of the mitral valve w/ redundant leaflets --> mitral valve prolapse
    • Leaflets are inappropriately elongated relative to the LV diameter
    • Decreased LV cavity size during systolic ejection --> redundant mtiral valve leaflets boy or prolapse into the atria --> inappropriate coaptation of the leaflet tips
  • Auscultatory findings
    • Mid to late systolic click: as valve leaflets prolapse into the LA
    • Mid to late systolic regurgitant murmur: follows sytolic click of inadequate coaptation fo the mtiral leaflets occur
  • Maneuvers that...
    • Decrease LV volume --> mitral valve click & sytolic murmur occur earlier in systole
    • Increase LV volume --> mitral valve click & systolic murmur occur later in systole

21

Treatment of Acute Mitral Regurgitation

  • Medical
  • Intra-aortic balloon pump (IABP)
    • Procedure
    • During diastole
    • During systole
  • Surgical

  • Medical
    • Diuretics
      • Relieve pulmonary vascular congestion
    • Vasodilators (ex. sodium nitroprusside)
      • Reduce peripheral vascular resistance to augment forward flow across the aortic valve
  • Intra-aortic balloon pump (IABP)
    • Procedure
      • Mechanical support in patients w/ cardiogenic shock
      • Percutaneous catheter based device that's placed in the cardiac catheterizaiton lab under fluroscopic guidance
    • During diastole: IABP inflates
      • Displaces blood in the descending thoracic aorta in a retrograde & antegrade direction
      • Retrograde flow increases MAP & augments diastolic blood flow into the coronary arteries --> improved coronary blood flow
    • During systole: IABP deflates
      • Creates a vaccuum in the descending throacic aorta
      • Facilitates forward cardiac output in patients w/ severe mitral regurgitation
  • Surgical repair or replacement of the mitral valve (definitive)

22

Nitroprusside

  • General
  • Mechanism
  • Cyanide

  • General
    • Potent predominant arteriolar vasodilator
    • Short half-life
    • Easily titrated in the ICU
  • Mechanism
    • Metabolized into NO
    • --> activates guanylate cyclase in vascular smooht muscl ecells
    • --> stimulates cGMP production
    • --> promotes Ca2+ uptake from the cytoplasm into the ER
    • --> decreases availability of intracellular Ca2+
    • --> vascular smooth muscle relaxation
  • Cyanide
    • Produced as a metabolic byproduct
    • Levels need to be monitored if nitroprusside is used for a prolonged period

23

Treatment of Chronic Mitral Regurgitation

  • Medical
  • Surgical
    • Mitral valve replacement
      • Mechanical valves
      • Bioprosthetic valves
      • Patient characteristics taken into consideration
    • Mitral valve repair
  • Primary challenge in surgical intervention of mitral valve disease

  • Medical
    • Diuretics: manage volume overload
    • Vasodilators: in patients w/ systemic hypertension
  • Surgical
    • Mitral valve replacement
      • Mechanical valves: more durable, mandate lifelong anticoagulation w/ warfarin
      • Bioprosthetic valves: less durable, don't require long term anticoagulation
      • Patient characteristics taken into consideration: age, underlying bleeding disorders, medical compliance
    • Mitral valve repair
      • Eliminated need for long term anticoagulation
      • Minimized prosthetic material implanted --> decreased risk of postoperative complications
  • Primary challenge in surgical intervention of mitral valve disease: optimal timing of surgery
    • Decreased LV funciton --> decreased postoperative survival
    • Patients w/ severe mitral regurgitation should undergo mitral valve repair or replacement prior to developing symptoms or LV systolic dysfunction
    • Patients w/ significant mitral regurgitation should be followed w/ annual or biannual echoes to assess adverse LV remodeling to assist the optimal timing of surgery