17 Cardiomyopathies Flashcards
What are the causes of DCM?
Idiopathic (unknown), familial, genetic (e.g. sarcomeric protein mutations), neurological disorders (e.g. Becker and Duchenne muscular dystrophies), toxins (e.g. alcohol and drugs), infection (e.g. myocarditis), inflammation (e.g. sarcoidosis, SLE and RA), tachycardia (e.g. chronic AF with RVR) and pregnancy (peripartum cardiomyopathy).
What are the echo characteristics of DCM?
Global LV dilatation, thin LV walls, global or regional LV systolic dysfunction, LA dilatation (chronic increased LV filling pressures), MR, RV dilatation and RV systolic dysfunction (chronic/severe), TR, RA dilatation (chronic/severe).
What are the echo characteristics associated with DCM?
MR, thrombi, pulmonary hypertension and pericardial effusions.
LV dilatation causes papillary muscle displacement and annular dilatation which causes MV leaflet tethering and functional MR.
LV systolic dysfunction causes blood stasis which causes thrombus formation.
LV systolic dysfunction increases LV filling pressures which increases LA pressure. This causes pulmonary arterial hypertension.
LV systolic dysfunction causes HF. This increases systemic venous pressure and increases pericardial fluid.
What is the cause of HCM?
HCM is a genetic cardiac disease (autosomal dominant).
What are the echo characteristics of HCM?
Asymmetrical LV hypertrophy (may be concentric), normal LV systolic function and impaired LV diastolic function, LVOT (and RVOT) obstruction (subaortic or midventricular), systolic anterior motion (SAM) of the anterior MV leaflet, MR, LA dilatation and RVH (RV wall thickness >5mm).
How is wall thickness assessed in HCM?
A LV wall thickness of ≥15mm indicates HCM (may be <15mm).
A LV wall thickness ≥30mm indicates severe HCM and is a risk factor for SCD.
A LV septal wall to a LV posterior wall ratio of ≥1.5:1 indicates asymmetrical hypertrophy.
How is LVOT obstruction, and LVOT gradient, assessed in HCM?
Normally, LVOT obstruction is dynamic so the PWD is sabre shaped.
Resting obstruction is defined as a LVOT gradient of ≥30 mmHg at rest.
Latent obstruction (induced or increased with exercise) is defined as a LVOT gradient of <30mmHg at rest but ≥30 mmHg with provocation.
Non-obstructive HCM is defined as a gradient <30mmHg at rest and with provocation.
How is LVOT obstruction induced in HCM?
The Valsalva manoeuvre decreases preload which increases LVOT gradients.
Standing from squatting decreases the preload and the afterload which increases the LVOT gradients.
Amyl Nitrite inhalation decreases afterload which increases LVOT gradients.
What are the echo characteristics associated with HCM?
SAM, apical aneurysms and apical thrombi, and papillary muscle abnormalities.
In SAM, the anterior MV leaflet towards the IVS during systole.
LV hypertrophy increases the LV pressures and LV stress which causes apical LV dilatation and thinning. This causes apical LV aneurysms which causes blood stasis which causes thrombus formation.
Papillary muscle hypertrophy and/or anterior displacement affect the MV and narrow the LVOT to cause LVOT obstruction.
What is SAM, what causes it, and what does it cause?
SAM is the movement of the anterior MV leaflet towards the IVS during systole.
The Venturi effect causes the SAM. In the Venturi effect, the increased LVOT velocity via the small LVOT creates a suction effect which draws the anterior MV leaflet towards the IVS during systole.
This causes subaortic LVOT obstruction and posteriorly directed MR.
How is HCM differentiated from the other causes of hypertrophy?
In hypertensive heart disease, there is mild and symmetric LV hypertrophy, the LV is normal in size or dilated, the LVOT gradient is normal or decreased and there is no family history.
In athletes’ heart, there is mild and symmetric LV hypertrophy, no family history and the hypertrophy decreases with detraining.
In amyloidosis, there is concentric LV hypertrophy, the ECG voltage is low and cardiac MRI shows LGE.
In Fabry’s disease, there is LV basal posterior hypertrophy, there are systemic symptoms and signs and there are alpha-galactosidase A mutations.
In Friedreich’s ataxia cardiomyopathy, there is concentric LV hypertrophy, there are systemic symptoms and signs (neurological) and there are FXN gene mutations.
What is the HCM SCD risk score?
The HCM SCD risk score estimates the risk of SCD in patients with HCM and guides ICD implantation.
The HCM SCD risk score is based on age, family history, maximum wall thickness, fractional shortening, LA diameter, maximum LVOT gradient, NSVT and unexplained syncope.
What are the echo characteristics of restrictive cardiomyopathy?
Normal LV size, normal LV systolic function, LV hypertrophy, diastolic dysfunction, restrictive filling patterns, bi-atrial dilatation and the absence of valvular and/or pericardial disease.
The LV is normal or small in size because the restriction decreases LV filling.
The wall thickness is dependent on the aetiology (normal in idiopathic restrictive cardiomyopathy but increased in infiltrative diseases).
The LV systolic function, and LVEF, are normal, but, with time, the increased stiffness and diastolic dysfunction may cause systolic dysfunction.
The GLS is decreased due to the increased stiffness in diastolic dysfunction and decreased contractility in systolic dysfunction.
The atria are dilated because the LV compliance is low so the LV filling pressures are high.
The E/A ratio is increased because there is increased early diastolic LV filling due to low LV compliance and high LA pressures and decreased late diastolic LV filling.
The DT is decreased because the LV compliance is low so the pressure between the LA and LV equalises quickly.
The E’ is decreased because the myocardial stiffness is increased and the myocardial relaxation is decreased.
The E/E’ ratio is increased because the LV filling pressures are increased.
The S velocities are decreased because the myocardial stiffness is increased and the myocardial relaxation is decreased.
What are the types of restrictive cardiomyopathy?
Idiopathic, Fabry’s disease, Danon’s disease, Friedrich ataxia, amyloidosis, sarcoidosis, endomyocardial fibrosis, carcinoid, and radiotherapy/drug induced.
Describe the aetiology and TTE characteristics of Fabry’s disease, Danon disease and Friedrich ataxia.
Fabry’s disease is an X-linked lysosomal storage disease in which globotriaosylceramide build ups in the heart causing hypertrophy, fibrosis and restriction.
Fabry’s disease is characterised by concentric LV hypertrophy, normal or small LV size, normal systolic function, decreased GLS, diastolic dysfunction, restrictive filling patterns, speckled myocardial pattern and/or endocardial fibrosis with valvular thickening.
Danon disease is genetic disease in which LAMP2 genetic mutations cause glycogen to build up in the myocardium causing hypertrophy and restriction.
Danon disease is characterised by severe LV hypertrophy, small LV size, normal or decreased systolic function, diastolic dysfunction, restrictive filling patterns and/or MV abnormalities including MVP and MR.
Friedrich ataxia is genetic disease in which FXN genetic mutations cause mitochondrial dysfunction.
Friedrich ataxia is characterised by concentric LV hypertrophy, normal or small LV size, normal systolic function, diastolic dysfunction, restrictive filling patterns, increased myocardial echogenicity and/or MV thickening and MR.
