Valvular Heart Disease

Introduction/Review

• Valve dysfunction can be:
  • Stenotic lesions --> overload of chamber proximal.
  • Regurgitation --> overload of both chambers proximal and distal. 
  • Both
• Often associated with chamber remodeling to adapt to pressure or volume overload (or both).
• Two types of hypertrophy:
  • Eccentric hypertrophy
    • Elongation of cells due to new sarcomeres layed down in series rather than in parallel. > myocytes become longer > LV dilates without thickening walls.
    • Progressive dilation leads to systolic dysfunction.
  • Concentric hypertrophy
    • Sarcomeres layed down in parallel -> thickening of LV wall -> causing smaller chamber. 
• Combined regurgitation and stenosis develop both concentric and eccentric hypertrophy (i.e. aortic regurg and stenosis)
  • Dominant abnormality dictates predominant remodeling. 
• Compensatory changes maintain heart function, and are asymptomatic for a long time.
• Acute valve changes lack compensatory remodeling, can can present as severe symptoms. and hemodynamically unstable
  (i.e. sudden volume overload)
  • I.e. acute papillary muscle rupture causing severe MR.

• Reading list:
  • AHA Valvular Guidelines 2014

Diagnostic Tests

• Indication for echocardiography in incidentally discovered murmur:
  • Symptomatic
  • Systolic grade 3 or louder, extending from S1 to S2 or longer, or diastolic murmurs..
• DO NOT investigate Grade ≤2 systolic non-radiating murmurs with no other abnormalities or reasons to investigate.

• Transthoracic Echo: LV size/function, pulmonary pressures, other disease and severity.
  • If image quality is poor --> TEE recommended.
• CT/MRI if echo not helpful, along with stress testing and BNP levels.
• Other indications for TEE for valve assessment:
  • Endocarditis, prosthetic valves, etc..

Aortic Stenosis

• Cause:
  • 1st most common: Calcific degeneration of trileaflet aortic valve is the most common cause.
    • Along with mitral annular calcification, this is often regarded as an atherosclerotic process.
  • 2nd most common: Congenital bicuspid valve disease.
    • Younger presentation, earlier need for intervention.
  • 3rd most common: Rheumatic heart disease (uncommon)
• Initially get aortic "sclerosis", thickening of aortic leaflets without obstruction or stenosis (25% of pts >65yo).
  • Often early-peaking systolic murmur is detected.  Echo: thickening of aortic leaflets, but no elevated pressure gradient.
  • In minority, can progress to aortic stenosis.
• Multiple RCT's using statins, but did not find slowed rate of progression AS.
• In aortic stenosis: increased LV afterload, results in concentric LV hypertrophy.  Pattern is adaptive to increased wall stress and helps maintain systolic function.  However as it progresses, diastolic dysfunction occurs, causing increased filling pressures and symptoms of angina/dyspnea.
  • High endocardial pressures and hypertrophy can cause subendocardial ischemia and angina.
• Symptoms
  • Reduced exercise tolerance and exertional dyspnea are earliest symptoms.
  • Onset of cardinal symptoms: (avg. survival 2-3y without intervention.)
    • Angina
    • Syncope
    • Heart failure 

• Physical Exam:

• Consequences:
  • Due to strict outlet size, fixed output, cardiac output limited with exertion.
    • syncope during exercise.
  • Loss of atrial kick, or decrease in diastolic filling time (i.e. exercise or Afib) can lead to deterioration.
  • BUT! asymptomatic patients have same survival time as those without AS.
• Some patients have low gradient (or moderate) but have small calculated valve area = "low gradient AS"
  • Dobutamine stress echo useful to differentiate from true AS (persists stenosis) vs. pseudo-stenosis (calc. valve area increases in response to dobutamine-induced increased contractility.

• Replacement is indicated for patients with severe aortic stenosis: valve gradient > 40 mmHg and Symptoms such as dyspnea, chest discomfort, syncope. LVEF is abnormal < 50% Poor response to exercise (hypotension, symptoms). Rapid AS progression (i.e. mean gradient > 60 mmHg). Other cardiac surgery is planned. If patient is asymptomatic: repeat physical exam in 6 months, repeat echo in 12 months.

• 
• Source: AHA guidelines
   
•  ETT: exercise treadmill test;

• Surgical valve repair/replacement is the only definitive treatment.
• Workup:
  • If systolic dysfunction and moderate AS --> do dobutamin stress echo to find the true severity of AS. (low flow, low gradient AS)
  • Cardiac catheterization to assess CAD.
• AS and heart failure
  • Cautious diuresis can improve symptoms.
    • Acute reduction in preload by diuresis can reduce stroke volume and BP drops.
  • Diuresis can be effective, but does not change indication for surgery.
  • Afterload reduction can be used in acute pulmonary edema (in systolic dysfunction), but titrate carefully to avoid hypotension. 
• Treatment options:
  • No pharmacologic therapy know to decrease progression of AS.
    • Treat concominant risk factors for CAD (high prevalence of CAD).
    • Only surgery offers survival benefit and durable symptom relief.
  • Balloon aortic valve replacement
    • Indicated for severe AS with hemodynamic compromise. (bridges to aortic valve repair).
    • Only mild improvement, and high rate of restenosis at 6mo.
    • High complications (stroke, MI, death)
  • Transcatheter aortic valve replacement (TAVI)
    • Reserved for very high predicted operative mortality.
    • Superior to medical therapy.
    • Mortality equivalent to surgical replacement.
    • Extends indications for patients who are not operative candidates.
  • ***Surgical valve repair*** (3-4% operative mortality?)
    • Recommended therapy.

Aortic Regurgitation

• Acute AR relatively uncommon.. can be due to:
  • dissection
  • endocarditis
  • trauma
• More commonly chronic, gradually progressive due to :
  • Bicuspid valve
  • Calcific degeneration
  • Myxomatous degeneration
  • Ascending Aortic pathology (Marfans, ascending aortic dilation, aortitis (AnkSpond or giant cell aortitis)).
  • Subvalvular abnormalities (subaortic stenosis, VSD causing aortic valve leafelet damage).
• Leads to volume and pressure overload of LV.
  • (Eccentric hypertrophy is due to increased preload, and concentric due to increased afterload/wall stress).
• Symptoms:
  • Dyspnea, angina, presyncope/syncope => mortality rate 10-20%/year.
  • (Most pts have symptoms)
• Complications:
  • LV systolic dysfunction (EF < 50%)
    • Progressive LV dilation -> contractility impairment -> global LV dysfunction 
  • LV dilation progressive, annual risk of symptoms increases + LV dysfunction, death up to 19% with LV end-systolic diameter >50mm. = marker of aortic vavel surgery in asymptomatic pt.
• Physical Exam:
  • Vitals: Wide pulse pressure

• Classic Murmur	Associated Features	Severity / Notes:
  Location: LLSB (valvar) or             RLSB (dilated aorta)   Quality: Diastolic; decrescendo   Radiates: NONE	- Enlarged, displaced apical impulse;  - S3 or S4; increased pulse pressure;  - bounding carotid and peripheral pulse   Chronic AR (many features! will list later)	- Acute, severe regurgitation murmur  may be masked by tachycardia, short  duration of murmur - Severity difficult to assess by physical   exam

• Echocardiogram
  •  
• Management:
  • Surgery required to reverse LV dysfunction (early stage).
  • Pharmacology
    • Vasodilators theortically reduce regurgitant volume, decrease symptoms, and reduce remodeling.
      • Indications for vasodilator therapy in AR:
        • Acute severe AR for short term hemodynamic improvement (before surgery)
        • AR with LV dysfunction in non-surgical candidates and concominant HTN.
        • Intra-aortic balloon counter-puslation is counterindicated in moderate/severe AR (increase back-flow and AR volume).
    • However, results from small trials did not show benefit on rate of progression. 
  • Surgical valve replacement is the only definitive management.  (see indication below)
    • The BEST management option.
    • Indications when symptoms or evidence of LV systolic dysfunction or severe dilation develops.

• 

Mitral Regurgitation

• Causes:
  • Organic (Primary)
    • Mitral valve prolapse
    • Rheumatic heart disease
    • Infective endocarditis
    • Collagen vascular disease
  • Functional (Secondary)
    • LV systolic dysfunction causing mitral annular dilation +/- restricted leaflet mobility.
    • CAD/ischemia can cause acute degeneration such as papillary muscle rupture/dysfunction.
    • chronic functional changes in the setting of LV dilatation and systolic dysfunction causing mitral valve leaflet tethering and malcoaptation
• Pathophysiology:
  • MR causes an increase in ventricular preload, whereas afterload is unchanged or reduced due to low impedance of flow into the LA.
  • Eccentric hypertrophy occurs to accommodate increased LV filling volume initially with normal diastolic filling pressure and maintain full stroke volume.  Eventually increased LA pressure results in dyspnea and pulmonary hypertension and progressive LA dilation results in AFib.
  • Volume overload to LV, ventricle adapts through eccentric hypertrophy/remodeling.
    • This compensatory mechanism maintains ventricular compliance... increases LV volume without increasing filling pressures.
    • With progression of regurgitation, and regurgitation, LV contractility is impaired.
  • Typicaly present in combination with AS due to mitral annular calcification and increased LV systolic pressures, can contribute to dyspnea when MR is moderate or severe.
  • MR ventricle is usually in a hyperdynamic state, so LVEF <60 = indication for surgery.
•  
• Physical Exam

• Classic Murmur	Associated Features	Severity / Notes:
  Location: Apex   Quality: Systolic; holo- or late systolic   Radiates: To axilla or back	- Systolic click in mitral valve prolapse; - S3; - apical impulse hyperdynamic and may be displaced if dilated left ventricle; - handgrip increases murmur intensity - in mitral valve prolapse, Valsalva maneuver moves onset of murmur closer to S1	- Acute, severe regurgitation may have soft or no holosystolic murmur, mitral inflow rumble, S3

• Echocardiography
  • Regurgitant Flow = 2piR^2 x Va
  • Effective Regurgitant Area (EROA)
  • Regurgitant Volume = EROA x VTI
  • Vena Contracta (where flow convergence happens - smallest diameter of stream - measure perpendicular to flow)
  • Severe =
    • Vena contracta ≥ 0.7cm
    • Regurg volume ≥ 60 mL
    • Regurg fraction ≥ 50%
    • ERO ≥ 0.40 cm^2
• Management
  • Organic: medical therapy is limited.
    • Acute symptomatic MR  --> CV surgery.
      • Afterload reduction with vasodilators with IV nitroprusside and stroke volume enhanacement with inotropic agents may stabilize patients pre-op.  Aortic balloon pumps can help mechanical ventricular unloading.
    • Chronic severe MR
      • No studies demonstrated clinical benefit with medical therapy.
      • Chronic ischemic MR with LV systolic dysfunction treatment of underlying heart failure with ACEi, beta-blocker witll decrease severity of MR, improve LV function, CV events.
      • Benefit of surgery unclear for functional MR.
      • Mitral valve repair: preferred alternative.  Better preservation of LV systolic function.
        • Improved outcomes with repair vs. replacement.
        • Valve repair has a benefit => no need for anticoagulation.  (replacement involves mechanical valve requiring anticoagulation). 

  • Indications for Mitral Valve Surgery:    1. Symptomatic Severe MR + LVEF > 30% (Gr I)   OR if Asymptomatic:      1.  LVEF < 60% (asymptomatic)     2.  LV End-Systolic Diameter > 40 mm (asymptomatic)      Gr IIA Indications    3.  Severe pulmonary HTN at rest (PASP >50 mm Hg) or during exercise (>60 mm Hg)    4.  New onset of atrial fibrillation      Gr IIB Indications     Severe Symptomatic MR and  LVEF < 30% can consider

  • Medical therapy:
    • Preload reduction
    • Treat low EF medically
    • Avoid vasodilator therapy (can affect LV) - can still use for hypertension?
  • Secondary MR
    • Worse outcomes (worsening LV dysfunction and adverse remodeling). 
    • Sparse data that correcting secondary MR improves mortality/sx.
      • Worse outcomes with repair (replacement recommended)
      •  

Mitral Stenosis

• Causes:
  • Often due to rheumatic heart disease. (can affect other valves, but mostly mitral).
    • Often women in 4-5th decades of life.
  • Rarely calcific disease can cause MS, most often mitral annular calcification in elderly
• Loading conditions are not significantly altered.
• Progressive stenosis of mitral valve, stenosis increases LA, pulmonary vein, and pulmonary artery pressures.
• Symptoms:
  • Exertional dyspnea.
  • Pulmonary edema in states of high flow (i.e. pregnancy), or impaired LV flow (afib/tach)
• Complications
  • Atrial fibrillation is the most common complication (30% of pts) and thromboembolism.
  • Pulmonary Hypertension
• Echo Parameters
  • Mean trans-mitral gradient: >10 mm Hg and < 1.0 cm^2 = severe mitral stenosis,
  • Mitral valve area:
    • ≤ 1.5 cm² in severe mitral stenosis
    • ≤ 1.0 cm² in very severe mitral stenosis.
• Physical Exam:

• Classic Murmur	Associated Features	Severity / Other Notes:
  Location: Apex (best heard in left             lateral decubitus position)   Quality: Diastolic;               low pitched, decrescendo   Radiates: NONE	- Opening snap after S2 if leaflets mobile; - irregular pulse if atrial fibrillation present	- Interval between S2 and opening snap is     short in severe mitral stenosis - Intensity of murmur correlates with transvalvar    gradient - P2 may be loud if pulmonary hypertension    present

• Management
  • Negative chronotropic drugs (B-blockers etc..)
    • Allow increased diastolic filling time and can improve symptoms.
    • Rate control of AFib is VERY important
  • Anticoagulation required if develop afib, risk is higher than in non-valvular afib.
  • Rhythm control unlikely to be successful unless MS is treated (large LA).
  • Diuretic therapy can improve pulmonary congestion. 
  • Indication for surgery (see below)
    • Must measure PA pressures with exercise echo (indication for surgery if elevated)
    • Mostly presence  of symptoms or pulmonary HTN.
  • Percutaneous balloon valvotomy often a procedure of choice (must r/o LA thrombus with TEE).
    • HIGH success rates.
• Balloon valvotomy is a possibility, but re-stenosis can occur.
  • Timing is crucial 

    - if done too early, miss asymptomatic period

    - if too late = pulmonary HTN + sx

  • Percutaneous balloon mitral valvuloplasty (PBMV) Indications:
    • Symptomatic (New York Heart Association [NYHA] functional class II, III, or IV)
    • AND severe mitral stenosis
    • AND valve morphology favorable for PBMV
    • AND absence of left atrial thrombus
    • AND absence of moderate to severe mitral regurgitation.
  • Complications:
    • MR, L-R shunt, perforation, embolism, MI
  • Surgery reserved for: (if cannot do percutaneously)
    • Open commisurotomy
    • Valve Reaplacement (last considered, higher mortality)

Tricuspid Regurgitation

• Two main causes:
  • Functional TR - due to processes like:
    • Pulmonary hypertension, which increases RV pressure leading to functional TR.
    • Pulmonic regurgitation
    • Left-sided disease
    • Cardiomyopathy (RV dilation)
  • Due to leaflet or myocardial dysfunction
    • Often RV systolic pressure would be < 30.
• Physical Exam

• Classic Murmur	Associated Features	Severity / Other Notes:
  Location: LLSB   Quality: Holosystolic   Radiates: LUSB	- Merged and prominent c and v waves in jugular venous pulse; - Murmur increases during inspiration	- Right ventricular impulse below sternum - Pulsatile, enlarged liver with possible ascites - May be higher pitched if associated with   severe pulmonary hypertension

• Treatment:
  • Indication for surgery:
    • Severe, symptomatic TR
    • RV enlargement/dysfunction??
  • Surgical options:
    • Tricuspid annuloplasty
    • Replacement

Valve Prophylaxis For Dental Procedures

• See Infective Endocarditis Section

Murmur Maneuvers

• Decrease Preload:
  • Valsalva
  • Squat-To-Stand
  • Cause decrease in preload.
  • Louder (earier initiation and longer duration of murmur in:
    • hypertrophic cardiomyopathy, mitral valve prolapse.
  • LVOT obstructions: Fixed valvular or subvalvular stenosis
    • If fixed, thse maneuvers decrease intensity of systolic murmur.
• Increase in afterload
  • Hand squeeze.
  • Increase LV systolic pressure and intensity of mitral valve regurgitation murmur.
• Other features:
  • Enlarged/displaced apical impulse.
  • S3/S4, systolic ejection click.

Echo Evalutation

Generally, follow-up echo evaluation

• Mild: q3-5y
• Moderate: q1-2y
• Severe: yearly.

Serial Evaluation of Asymptomatic Patients with Left-Sided Valvular Conditions

(Source: MK--SAP16)

Management

Indications for Interventions for Valvular Heart Conditions

• Generally development of LV systolic dysfunction = poor prognostic factor.
• However, sometimes fixing reversible ischemia by stenting, can improve papillary function and help MR.
• Generally medical therapy helps acute management, but no effect on progression of disease and mortality.
  • Acute valve dysfunction (i.e. mitral valve proplase) is a surgical emergency.  Afterload reduction and inotropes can help stabilize the patient, but surgery is often needed for definitive management.

Source: MK-SAP16

Physical Exam Findings Summary

Valvular and Other Cardiac Lesions and Their Associated Examination Findings

References

• MKSAP 16

• MKSAP 17

• ACC/AHA Guidelines 2014 (attached)

• JACC valvular heart disease review

•  

  Cardiac auscultation: rediscovering the lost art.  (Chizner, 2008)