Cardiomyopathy Flashcards
What is the types of and epidemiology of cardiomyopathy?
Hypertrophic CM:
- Most common genetic cardiovascular disease
- 1/500; more common in men and black people
- Most common cause of sudden cardiac death in young people and athletes
- Most commonly presents in 2nd or 3rd decade of life but may present at any age
Dilated:
- c. 2/10,000
- Known genetic risks
- Usually in adults aged 20-60
- M > F, and black > Caucasian
Arrhythmogenic right ventricular:
- Uncommon, c.1/2000
- M > F
- Familial in 30-50%
- Presents in adolescence/early adulthood (15-35)
Restrictive:
- Least common - c.5% of all cardiomyopathy
- Most patients are elderly
- M = F
- Familial inheritance not a strong factor
What is the aetiology and pathophysiology of hypertrophic cardiomyopathy?
Genetics:
- AD inheritance with variable penetrance and expressivity
- Minority of sporadic non-familial cases
Myocyte disarray and fibrosis
- Troponin T mutations have an increased risk of sudden death in patients with or without significant LVH
Hypertrophy can occur anywhere in the left ventricle, most commonly in the anterior ventricular septum
- Impaired diastolic filling due to rigidity of LV
What is the aetiology and pathophysiology of dilated cardiomyopathy?
Genetics:
- 60+ gene mutations associated
- 30-48% have an inherited form
- Genes encoding sarcomeric, cytoskeletal, nuclear membrane etc
Other risk factors/causes:
- Ischaemia
- Alcoholism
- Thyrotoxicosis
- SLE, RA
- Cocaine, amfetamines, heroin
- Haemochromatosis, amyloidosis, sarcoidosis
- HIV, adenovirus, coxsackie, CMV, toxoplasmosis, Lyme etc
Ventricular chamber enlargement and contractile dysfunction
- Normal left ventricular wall thickness
- Right ventricle might also be dilated and dysfunctional
What is the aetiology and pathophysiology of arrhythmogenic right ventricular cardiomyopathy?
Genetics:
- AD (most common) and AR forms
Precise aetiology is unknown
Fibro-fatty replacement of RV myoctypes due to apoptosis, inflammation or genetic causes
What is the aetiology and pathophysiology of restrictive cardiomyopathy?
Usually no cause found
Some possible causes:
- Amyloid heart disease (most common cause of restrictive)
- Sarcoidosis
- Haemochromatosis
Normal LV cavity size and systolic function but with increased myocardial stiffness
- Ventricle is incompliant and fills predominantly in early diastole
- Raised LA pressure + dilatation
How does hypertrophic cardiomyopathy present?
Mostly asymptomatic
- Incidental on examination, ECG or echo
Symptoms may develop with age:
- Dyspnoea (can be alcohol induced)
- Chest pain
- Palpitations
- Syncope (can be alcohol induced)
- Profound exercise limitation
- Recurrent arrhythmias
Cause of sudden death, especially in the young
- Due to arrhythmias and/or obstruction of LV outflow tract (25%)
- Unexplained syncope = risk marker for sudden death
How does dilated cardiomyopathy present?`
Many are asymptomatic
Most presenting features will be of heart failure:
- Dyspnoea
- Weakness
- Fatigue
- Oedema
- Raised JVP
- Pulmonary congestion
- AF
Depending on causes:
- Viral prodrome
- Signs of alcohol abuse etc.
Complications:
- Heart failure
- Stroke from thromboembolism
- Arrhythmia
- Sudden death, especially in the young
How does arrhythmogenic cardiomyopathy present?
Palpitations, presyncope or syncope
Possible later stages:
- Biventricular or R side heart failure
Cause of sudden death, especially in the young
How does restrictive cardiomyopathy present?
Usually with heart failure but with normal systolic function:
- Dyspnoea
- Fatigue
Up to 75% develop AF
What do you find on examination of someone with hypertrophic cardiomyopathy?
May be normal
Forceful apex beat
- Double impulse if LV outflow tract is obstructed
Late ejection systolic murmur
- Increased by standing
- Diminished by squatting
Possible AF
What do you find on examination of someone with dilated cardiomyopathy?
May be normal
Displaced apex beat
Raised JVP
Loud third and/or fourth heart sounds
What do you find on examination of someone with arrhythmogenic cardiomyopathy?
May be normal
Variable changes in pulse
Signs of right ventricle dysfunction
What do you find on examination of someone with hypertrophic cardiomyopathy?
Raised JVP
Hepatomegaly
Oedema
Ascites
AF
How do you investigate cardiomyopathy?
ECG:
- Various features for all including sinus tachycardias, BBBs etc. , non-specific changes
- AF
Echo +/- Doppler:
- Will show signs of hypertrophy or dilatation
- Possible signs of obstruction
- Looking at filling and flow changes
CXR:
- Features may include cadiomegaly, pulmonary oedema etc.
Cardiac MR:
- More detail than both the above imaging modalities
Other:
- Cardiac catheterisation
- Angiography
- BNP
- Endomyocardial biopsy
- Genetic analysis
How do you treat hypertrophic cardiomyopathy?
Alleviate symptoms + reduce risk of sudden death
Rhythm control:
- Often necessary
- Anti-arrhythmic drugs or catheter ablation
- Beta-blockers, verapamil; amiodarone
Anticoagulation if concomitant AF
Surgery:
- Septal myomectomy (or alcohol septal ablation) - to reduce left ventricular outflow gradient
- implantable cardioverter defibrillator if multiple risk factors for sudden death
- Heart transplant necessary if refractory heart failure
