Valvular Heart Disease

Valvular Heart Disease

•     Left sided valve lesions:

–      Aortic: stenosis / regurgitation

–      Mitral: stenosis / regurgitation

•     Right sided valve lesions:

–      Tricuspid: stenosis / regurgitation

–      Pulmonary: stenosis / regurgitation

•    Prosthetic heart valves

Aortic stenosis

Aetiology

•       Aortic stenosis may be congenital or acquired.

•       Congenital malformations may be tricuspid, bicuspid or more rarely unicuspid / quadricuspid

•       Acquired causes include the following:

      -     Degenerative disease

      -     Rheumatic disease

      -     Calcific e.g. end-stage renal failure, Paget’s disease

      -     Miscellaneous e.g. rheumatoid involvement

Pathophysiology

          

Symptoms

•       Exertional dyspnoea or fatigue

•       Angina

•       Syncope

Physical findings

•       Slow rising pulse

•       Reduced systolic and pulse pressure

•       Systolic thrill over the aortic area

•       Ejection systolic, crescendo-decrescendo murmur

•       Soft or inaudible second heart sound

•       ECG:  LVH, AV node conduction defects

Echocardiography

•       Thickened valves with reduced motion, sometimes calcified

•       Grading of stenosis severity is as follows:

      -     Normal valve area = 3-4cm2

      -     Mild stenosis = 1.5-3cm2

      -     Moderate stenosis = 1.0-1.5cm2

      -     Severe stenosis ≤ 1.0cm2

•       When stenosis is severe, the peak gradient across the aortic valve is usually > 60mmHg.

Medical therapy

•      Conservative treatment should be offered for mild to moderate aortic stenosis and to asymptomatic patients with severe aortic stenosis as follows:

     -    Advise to report symptoms

     -    Avoid vigorous exercise

     -    Antibiotic prophylaxis for endocarditis

     -    Regular follow-up ± echocardiography

Surgical/ Interventional therapy

•       Aortic valve replacement should be offered to the following:

      -     Symptomatic pts with severe AS

      -     Pts with severe AS undergoing CABG surgery

      -     Pts with moderate AS undergoing CABG surgery

      -     Asymptomatic pts with severe AS and LV dysfunction

•       Balloon valvuloplasty: bridge to surgery in haemodynamically unstable patients, or palliation for patients with serious comorbid conditions

•       Transcatheter aortic valve replacement

Aortic valve replacement

•      In the absence of LV dysfunction, operative risk is

     2-5%.

•      Indicators of higher mortality are NYHA class, LV dysfunction, age, concomitant coronary artery disease, and aortic regurgitation.

•      Valve replacement usually results in reduced LV volumes, improved LV performance and regression of LV hypertrophy.

Transcatheter Aortic Valve (TAVI)

•       Novel alternative therapy

•       Performed via femoral, subclavian or transapical approaches

•       Currently reserved for high risk, symptomatic severe degenerative aortic stenosis

Aortic regurgitation

Aetiology

•       Either due to primary disease of the aortic valve or wall of the aortic root or both.

•       Causes of primary aortic valve disease include:

      -     Congenital eg. bicuspid aortic valve

      -     Acquired:  rheumatic valve disease, infective       endocarditis, trauma,   connective tissue disease.

•       Causes of primary aortic root disease include:

      -     Degenerative, cystic medial necrosis (eg. Marfan’s), aortic dissection, syphilis, connective tissue disease,      hypertension.

Clinical history

•       Chronic severe AR

         Dyspnoea is the principal symptom

         Syncope is rare and angina is less frequent than in

         aortic stenosis.

•       Acute severe AR

          LV decompensation occurs readily with fatigue,

          severe dyspnoea and hypotension.

Pathophysiology of aortic regurgitation

                               

Physical findings

•       Collapsing pulse

•       Wide pulse pressure

•       Peripheral signs- De Musset’s, Corrigan’s, Quinke’s, Muller’s, Duroziez’s

•       Hyperdynamic apex beat

•       Early blowing diastolic murmur

•       ECG:  Left axis deviation, LV hypertrophy.

•       CXR:  Cardiomegaly, aortic calcification, aortic root dilatation

Echocardiography

•       Colour flow

      - width of the jet at its origin

      - extent into the LV

•       Doppler

      - Rate of decline of aortic reguritant flow

      - Diastolic flow reversal into the descending aorta

Management

•       Medical treatment

      -     Diuretics, digoxin, salt restriction

      -     Vasodilators

      -     Endocarditis prophylaxis

•       Without surgery, death usually occurs within 4 years of developing angina and within 2 years after onset of heart failure.

Surgical therapy

•       Severe acute AR requires prompt surgical intervention.

•       Chronic severe AR

      -     Symptomatic patients with normal LV function

      -     Symptomatic patients with LV dysfunction or dilatation

      -     Asymptomatic patients with LV dysfunction or dilatation   (EF<50% or end-systolic diameter > 55mm)

•       Aortic valve and root replacement- if aortic root diameter is ≥ 50mm.

Mitral stenosis

Aetiology

•       Rheumatic

•       Congenital

•       Carcinoid, SLE, rheumatoid arthritis,  mucopolysaccharidoses.

•       Left atrial myxoma, ball-valve thrombus, infective endocarditis with large vegetation and cor triatriatum.

Rheumatic mitral stenosis

•       Fusion of the valves, commisures and chordae

•       Symptoms usuually occur in the 3rd or 4th decade, but mild MS in the aged is becoming more common.

•       25% of patients have pure mitral stenosis and two-thirds are female.

•       Lutembacher’s syndrome- associated with an atrial septal defect

Pathophysiology

•       Normal mitral valve area = 4-6cm2.

•       A mitral valve area ≤ 1cm2 equates to severe mitral stenosis.

•       Symptoms usually develop when  mitral valve area ≤ 2.5cm2

•       Symptoms in mild mitral stenosis usually precipitated by exercise, emotional stress, infection, pregnancy or fast atrial fibrillation.

Natural history

•       Long latent period of 20 to 40 years

•       Once significant limiting symptoms occur, 10-year survival rate is 5-15%.

•       With severe pulmonary hypertension, mean survival falls to

     < 3 years.

•       Mortality from untreated mitral stenosis is due to progressive heart failure (60-70%), systemic embolism (20-30%) and pulmonary embolism (10%).

Clinical features

•       Dyspnoea

•       Haemoptysis may also occur

•       Angina

•       Embolic events

Physical findings

•       Mitral facies

•       Tapping apex beat

•       Right ventricular heave, loud P2

•       Loud first heart sound.

•       Opening snap.

•       Rumbling, mid-diastolic murmur with presystolic accentuation in sinus rhythm.

Echo evaluation

•       Assessment of valve morphology: degree of leaflet thickness, mobility and calcification and extent of subvalvular fusion.

•       Estimation of left atrial size.

•       Doppler echo: estimation of mitral valve area, transvalvular gradient and PA pressure.

Medical treatment

•       The asymptomatic patient with mild mitral stenosis should be managed medically. Medical therapy includes:

      -  Avoidance of unusual physical stress.

      -  Salt restriction.

      -  Diuretics if needed.

      -  Control of heart rate – β-blocker or digoxin.

      -  Anticoagulation for AF or prior embolic event.

      -  Annual follow-up.

      -  Echocardiography if deterioration in clinical condition.

Management of symptomatic mitral stenosis

•       Patients with symptoms should undergo clinical re-evaluation with echocardiography.

•       NYHA class II symptoms and mild mitral stenosis may be managed medically.

•       NYHA class II symptoms and at least moderate stenosis (MVA≤1.5cm2 or mean gradient ≥5mmHg) may be considered for balloon valvuloplasty.

•       NYHA class III or IV symptoms and severe mitral stenosis should be considered for balloon valvuloplasty or surgery.

Mitral valve replacement

•       Severe mitral stenosis and contraindications to surgical commisurotomy or balloon valvuloplasty:

      -  Restenosis following surgical commisurotomy or balloon        valvuloplasty

      -  Significant mitral regurgitation

      -  Extensive calcification of the subvalvular apparatus.

•       Operative mortality ranges from 3-8% in most centres.

Mitral Regurgitation

Chronic MR

Acute MR

Mitral valve prolapse

Aetiology

Mitral regurgitation may be caused by abnormalities of the valve leaflets, chordae tendinae, papillary muscles or mitral annulus:

•         Valve leaflets

   - myxomatous degeneration

   - rheumatic heart disease

   - infective endocarditis

•         Chordae tendinae

   - congenital, infective endocarditis, trauma, rheumatic fever, myxomatous

•         Papillary muscles

   - myocardial ischaemia, congenital abnormalities, infiltrative disease

•         Mitral annulus

   - dilatation eg. ischaemic or dilated cardiomyopathy

   - calcification due to degeneration, hypertension, diabetes,                   

     chronic renal failure

Clinical features

•       Symptoms usually occur with LV decompensation: dyspnoea and fatigue.

•       Physical findings include:

     - Pulse: sharp upstroke

     - Apex: displaced, hyperdynamic

     - Pansystolic murmur

Natural history

•       The natural history of chronic MR depends on the volume of regurgitation, the state of the myocardium and the underlying cause.

•       Preoperative LV end-systolic diameter is a useful predictor of postoperative survival in chronic MR.

•       The preoperative LV end-systolic diameter should be < 45mm to ensure normal postoperative LV function.

Medical treatment

•       Symptomatic patients may benefit from the following drug therapy whilst awaiting surgery:

•       Vasodilator therapy

•       Diuretics

•       Digoxin / Beta-blockers in presence of atrial fibrillation.

•       Endocarditis prophylaxis

Surgical treatment

•       Symptoms or left ventricular end systolic diameter ≥45mm.

•       Mitral valve repair or replacement.

•       Mitral valve repair better preserves LV function and avoids the need for chronic anticoagulation.

Acute mitral regurgitation

Aetiology

Important causes of acute mitral regurgitation include:

•             Infective endocarditis

•             Ischaemic dysfunction or rupture of papillary       muscle.

•             Malfunction of prosthetic valve.

Chronic versus Acute MR

Finding                       Chronic MR                  Acute MR

Symptoms                 subtle onset                         obvious

Appearance             normal/mildly                        severely ill

                                 dyspnoeic

Tachycardia              not striking                         always present

Apex beat                  displaced                         not displaced

Systolic thrill                   common                      a bsent

Murmur                         harsh pansystolic         soft or absent early     systolic component

ECG-LVH               usually present                      absent

CXR                            severe cardiomegaly     normal heart size

Acute mitral regurgitation

Medical therapy

The following therapies may be beneficial in reducing the severity of MR

- Vasodilator therapy

- Inotropic therapy

- Intra-aortic balloon counterpulsation

Surgical therapy

•        Indicated in patients with acute severe MR and heart  

  failure.

•        Higher mortality rates than for elective chronic MR

Mitral valve prolapse

General features 

•         2-6% of the general population

•         Twice as common in women. 

•         Due to myxomatous proliferation of the mitral valve.

•         Primary condition, or secondary finding in connective tissue

   diseases e.g. Marfan’s syndrome.

•         Vast majority asymptomatic.

•        Palpitations, dizziness, syncope, or chest discomfort.

•        Mid-systolic click, late systolic murmur

Echocardiographic criteria

•         M-mode criterion: ³ 2mm posterior displacement of one or both

   leaflets.

•         2-D echo findings: Systolic displacement of one or both leaflets

   within the left atrium in the parasternal long-axis view; leaflet

   thickening, redundancy, chordal elongation and annular dilatation.

Natural history

•         Benign prognosis in most patients

•         Complications may occur in patients with a systolic murmur,

   thickened leaflets, an increased LV or LA size, especially in men

   > 45 years old

•         Complications include progressive mitral regurgitation, infective

   endocarditis, cerebral emboli, arrhythmias and rarely sudden death.

Management

•       Asymptomatic patients without MR or arrhythmias have an excellent prognosis – follow-up every 3-5 years.

•       Patients with a long systolic murmur may show progression of MR and should be reviewed annually.

•       Severe MR requires surgery, often mitral valve repair.

Tricuspid stenosis

•       Almost always rheumatic

•       The low cardiac output state causes fatigue; abdominal discomfort may occur due to hepatomegaly and ascites.

•       The diastolic murmur of tricuspid stenosis is augmented by inspiration.

•       Medical management includes salt restriction and diuretics.

•       Surgical treatment in patients with a valve area <2.0cm2 and a mean pressure gradient >5mmHg.

Tricuspid regurgitation

•       Most common cause is annular dilatation due to RV failure of any cause

•       Symptoms and signs result from a reduced cardiac output, ascites, painful congestive hepatomegaly and oedema.

•       The pansystolic murmur of TR is usually loudest at the left sternal edge and augmented by deep inspiration.

•       Severe functional TR may be treated by annuloplasty or valve replacement. Severe TR due to intrinsic tricuspid valve disease requires valve replacement.

Pulmonary stenosis

•       Most commonly due to congenital malformation

•       Survival into adulthood is the rule, infective endocarditis is a risk and right ventricular failure is the most common cause of death.

•       Carcinoid plaques may lead to constriction of the pulmonary valve ring.

Pulmonary regurgitation

•       Most common cause is ring dilatation due to pulmonary hypertension, or dilatation of the pulmonary artery secondary to a connective tissue disorder.

•       May be present and well-tolerated for many years

•       The clinical manifestations of the primary disease tend to overshadow the pulmonary regurgitation.

•      Physical examination

–       right ventricular heave

–       high-pitched, blowing, early diastolic decrescendo murmur

•         left sternal edge

•         augmented by deep inspiration.

•      Pulmonary regurgitation is seldom severe enough to require specific treatment. Surgery may be required because of intractable RV failure.

Prosthetic valves

Prosthetic valves may be divided into 2 broad categories:

Mechanical valves

•        Very good durability.

•        Require long-term anticoagulation.

•        May cause mild haemolysis.

Bioprosthetic (tissue) valves

•        Porcine variety most commonly used.

•        Limited durability.

•        Anticoagulation for first 3 months only.

Mechanical versus tissue valves

•       No difference in survival, haemodynamics or in probability of

    developing endocarditis, valve thrombosis or systemic embolism.

•       Valve-related failure is much more common with tissue valves.

•       Anticoagulant-related bleeding occurs with mechanical valves.

•       Elderly patients tend to receive tissue valves.