🥀Cardiomyopathies

DCM:

Dilatation (BSA corrected) and systolic impairment (quantified) of LV.

Replacement of muscle architecture with diffuse scarring.

Need to look at regional pattern of scarring due to difficulty distinguishing from ischaemic CM. DCM should be diffuse without RWMAs.

Common causes:

• Myocarditis
• Pregnancy
• Alcohol
• Prolonged tachycardia

Often associated with pulm htn and dilatation of all cardiac chambers. RV dysfunction is poor prognostic factor. Functional MR and TR is common.

Normal wall thickness with spherical LV. Early AV closure and delayed MV closure.

Dobutamine stress echo may demonstrate contractile reserve.

Important to assess for apical thrombus. Spontaneous echo contrast indicates low flow.

Diastolic function often demonstrates restrictive filling. Identifying significantly reduced filling time will give a marker of overall clinical state. Below image shows well patient with adequate LV filling time (top) when compared with significantly reduced filling time in a patient in pulmonary oedema (bottom). Can see v rapid filling and long period of MR on Doppler.

Important to differentiate from non-compaction cardiomyopathy.

Failure of myocardial development during embryogenesis creating large trabeculations in LV extending into chamber. Colour doppler can be seen to spread all the way to the epicardial border (reduce nyquist).

HCM:

Myocyte disarray – presenting as LVH, contractile dysfunction and arrhythmia substrate.

Genetic inheritance.

Classically asymmetrical:

• 65% asymmetrical, typically septal. Can present as apical.
• 35% symmetrical – need to exclude htn/valve related etc.
• May be obstructive or non-obstructive.

Systolic function is often preserved and ejection fraction normal or high. However, small LV cavity so SV is often low.

Diastolic function impaired.

Risk factors for arrhythmias:

• FHx of VT/SCD.
• Syncope, non sustained VT.
• Reduced BP during exercise.
• Severe LVH >30mm on echo.
• LVOT obstruction.
• LV dysfunction.

Key is to identify diagnosis and any outflow tract obstruction which appears as:

• Systolic anterior motion of the anterior MV leaflet. – see visually or on M-mode. Due to venturi effect. May see posteriorly directed MR jet.
• Early systolic closure of AV.
• Increased PW velocities in outflow tract. Need to measure highest gradient, may have subvalvular/mid LV obstruction so don’t just measure velocity in LVOT. Obstructive if gradient >30mmHg.
• Sabre shaped LVOT jet. Velocity increases through systole due to progressive narrowing of LVOT.
• Measure degree of hypertrophy at 3/6/9/12 o clock in each level of LV.
• Can get apical ballooning/aneurysm formation if mid cavity obstruction.
• Dynamic obstruction – Bernoulli equation not strictly accurate. Velocity will increase with exercise.
• Can develop HCM to DCM transformation.

Restrictive CM:

Caused by infiltration or deposition:

• Amyloid.
• Haemochromatosis.
• Endocardial fibrosis.
• Fabry’s disease.
• Hypereosinophilic syndrome (Loeffler’s).
• Sarcoid.
• Glycogen storage disease.

Features:

• LVH with small LV cavity.
• Normal EF – but small cavity size so SV is actually low.
• Impaired long axis function – often do not see either annulus move towards apex.
• Impaired diastolic function.
• Severe bi-atrial enlargement.
• Pulmonary hypertension.

Amyloid (note also small QRS complexes despite apparent LVH, v common for amyloid). Note the echo-bright myocardium and speckled appearance:

Differentiating between constrictive pericarditis and restrictive cardiomyopathy is popular question.

Arrhythmogenic RV CM:

Diffuse segmental condition with inflammation of myocardium, myocyte death with fibrous fatty replacement.

Aneurysms of RV free wall.

Echo-bright myocardium and moderator band.

Remember to look for RV apical thrombus – rare but can be seen.

RVOT is always enlarged – can measure either in PLAX of PSAX.

• RVOT plax: >32mm or >19mm/m2 and presence of regional RV akinesia, dyskinesia or aneurysm is major criteria.
• 29mm to <32mm (or 16mm/m2 to 19mm/m2) and presence of regional RV akinesia or dyskinesia is minor criteria.

• RVOT psax: RVOT1 >36mm or >21mm/m2 in presence of regional RV akinesia, dyskinesia or aneurysm is major criteria.