Non-Ischaemic Acquired Heart Disease

Definition

• An incompetent mitral valve allowing regurgitant flow from the left ventricle (LV) into the left atrium (LA) during systole (mid-to-late systolic murmur) ▸ maintaining an adequate stroke volume requires an increased ventricular stroke volume and ejection fraction

Clinical presentation

• Acute regurgitation (e.g. ruptured chordae tendineae): sudden volume loading with acute pulmonary oedema/heart failure

• Chronic regurgitation (e.g. hypertrophic cardiomyopathy): volume overload with dilated left cardiac chambers ± cardiac failure

Radiological features

• CXR Selective left atrial enlargement may be absent, slight or moderate (the left atrial appendage is usually not enlarged)

  • Acute severe non-rheumatic disease: a normal heart size ▸ pulmonary oedema

  • Later stages: compensatory left ventricular dilatation

• Echocardiography It can assess coaptation of the valve leaflets and any regurgitant jet direction (with Doppler assessment)

• CMR mitral regurgitation seen as a retrograde jet through the mitral orifice secondary to turbulent flow and spin dephasing ▸ CMR can also quantify the degree of regurgitant flow (e.g. phase contrast velocity flow mapping)

Pearls

• Mitral valve prolapse: systolic bowing of the mitral leaflet >2 mm beyond the annular plane into the atrium (due to rupture or elongation of the chordae tendineae) ▸ most common cause of non-ischaemic mitral regurgitation

• Chordal rupture: following bacterial endocarditis or MI leading to eversion of the valve leaflet into the atrium during systole and preventing full closure

• Functional mitral regurgitation: occurs in dilated cardiomyopathy or ischaemic failure, with a normal valve

• Mitral annulus calcification : this rarely occurs before 70 years of age (F>M) ▸ it is seen with hypercalcaemic states (e.g. end-stage renal disease) ▸ it may lead to mild mitral regurgitation (but rarely stenosis) ▸ there is a possible increased risk of infective endocarditis ▸ it is also associated with transient ischaemic attacks (due to emboli)

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    CXR it is seen as a C-shaped open ring (the gap occurs where the anterior mitral valve leaflet base is in contact with the posterior aortic valve ring)

• Dystrophic calcification of the mitral valve: unlike mitral annulus calcification this is very suggestive of a rheumatic aetiology

Definition

• This is usually due to chronic rheumatic fever (leading to leaflet thickening/nodularity/commissural fusion)

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    The most common result is a mixture of stenosis and regurgitation (both cannot be severe at the same time)

• Mild stenosis: mitral area >1.5 cm ² ▸ mean gradient <5 mmHg

• Moderate stenosis: 1–1.5 cm ² ▸ mean gradient 5–10 mmHg

• Severe stenosis: <1 cm ² ▸ mean gradient >10 mmHg

Clinical presentation

• It is usually asymptomatic until a critical stenosis develops (e.g. following an attack of rheumatic fever)

• Atrial fibrillation (due to atrial dilatation) ▸ dyspnoea (pulmonary venous hypertension) ▸ sequelae of atrial thrombus embolization ▸ secondary pulmonary arterial hypertension

Radiological features

• CXR

  • Left atrial enlargement : the left atrial appendage is particularly affected (suggesting a rheumatic aetiology) ▸ simple straightening of the left heart border to a large bulge at the appendage ▸ a grossly dilated left atrium can enlarge to the right and also posteriorly (causing oesophageal displacement and dysphagia)

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      A ‘double density’ behind the heart

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      Widening of the subcarinal angle

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      Left ventricular enlargement is not a feature (cf. mitral regurgitation)

  • Parenchymal lung changes of haemosiderosis and intrapulmonary ossification: these may appear after several years of pulmonary venous congestion

  • Curvilinear calcification: this may occur within the left atrial wall or within the clot lining the wall

• Echocardiography Standard for diagnosis ▸ evaluates mitral valve morphology and valve mobility

• CMR Can show restricted mitral valve opening ▸ thickened leaflets ▸ commissural fusion ▸ antegrade jet due to turbulent flow across a stenotic valve ▸ ‘fish mouth’ appearance on short axis images ▸ ‘hockey stick’ appearance due to bowing of a thickened/fibrotic anterior leaflet during diastole ▸ can directly measure the orifice area ▸ mitral valve area can be calculated via mitral flow velocity analysis

Pearls

• Congenital mitral stenosis is rare

• Treatment: valve replacement or valvuloplasty for severe stenosis

Definition

This may result from aortic valve cusp or aortic wall disease

• Acute aortic regurgitation: causes include bacterial endocarditis or rarely occurring after trauma or aortic dissection (with acute avulsion of a leaflet into the left ventricle) ▸ it develops rapidly with increasing left ventricular end-diastolic pressure and acute heart failure

• Chronic aortic regurgitation: congenital deformities (e.g. bicuspid aortic valve or Marfan's syndrome) ▸ rheumatic heart disease ▸ syphilitic aortitis ▸ ankylosing spondylitis ▸ a descending aortic aneurysm

Radiological features

Chronic

CXR

There may be severe left ventricular enlargement (paralleling the disease severity) ▸ moderate thoracic aortic enlargement (or severe enlargement with aortitis or chronic dissection) ▸ there is infrequent valve calcification ▸ if mitral valve disease is also present then left atrial enlargement may dominate the picture

CMR

Precise assessment of regurgitant volume can be estimated from the degree of signal loss ▸ it also allows assessment of the LV function (ECG-gated cardiac CT is an alternative if MRI is contraindicated)

Pearls

• Chronic disease: this allows the left ventricle to dilate with an increased compliance ▸ end-diastolic pressures remain low and the patient remains asymptomatic until heart failure develops ▸ once failure develops the prognosis is markedly worsened

• Acute disease: ventricular compliance cannot compensate ▸ it is associated with a very large rise in ventricular end-diastolic pressures (limiting regurgitant flow)

Definition

Stenosis with a valve area < 1.0 cm ² is severe ▸ stenosis can be:

• Supravalvular: a rare lesion associated with Williams–Beuren syndrome (genetic disorder of elastin which is responsible for aortic recoil) – characteristic hourglass aortic narrowing (or diffuse tubular narrowing of the ascending aorta in 30%)

• Valvular:

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    Calcific aortic stenosis : this is most commonly due to degenerative calcium deposition on normal aortic cusps (cf. mitral stenosis where calcium is deposited on an already stenosed valve) ▸ it was previously commonly due to calcification of a congenitally deformed bicuspid valve

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    Rheumatic aortic stenosis : this causes inflammatory fusion of the commissures of the aortic valve cusps and is often associated with aortic regurgitation and mitral valve involvement ▸ associated with pronounced dyspnoea due to the associated mitral valve disease

• Subvalvular (least common): commonly caused by hypertrophic cardiomyopathy

Radiological features

Rheumatic aortic stenosis

CXR

The appearances are commonly dominated by any associated mitral valve disease ▸ post stenotic dilatation is rare; gross valvular calcification is rare

Pearls

There is a frequent association with coronary artery disease – coronary angiography is therefore necessary prior to valve replacement surgery

Clinical presentation

High venous pressures with a big ‘v’-wave and a pulsating enlarged liver