Cardiomyopathies Flashcards
What are the three main types of cardiomyopathy?
- Hypertrophic cardiomyopathy
- Dilated cardiomyopathy
- Arrythmogenic cardiomyopathy
What is a cardiomyopathy?
A myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valvular disease and congenital heart disease sufficient to cause the observed myocardial abnormality.
Which cardiomyopathy is the most common?
Hypertrophic cardiomyopathy
Which cardiomyopathy is most commonly seen following a heart transplant?
Dilated cardiomyopathy
Clinical presentation of cardiomyopathy
What is hypertrophic cardiomyopathy?
Increased ventricular wall thickness or mass without loading conditions sufficient to cause the observed abnormality.
Cause of hypertrophic cardiomyopathy
Most common genetic cardiac disorder and is inherited in an autosomal dominant fashion (although around 50% of cases are sporadic)
Three cardinal features of hypertrophic cardiomyopathy
- Hypertrophy (usually asymmetrical left ventricular hypertrophy)
- Myocyte disarray
- Fibrosis
Clinical features of hypertrophic cardiomyopathy
- Most people with hypertrophic cardiomyopathy are asymptomatic
- May present with angina, dyspnoea or syncope if left ventricular outflow tract (LVOT) obstruction occurs
- Sudden death is usually caused by arrhythmias or severe LVOT obstruction
Managment of hypertrophic cardiomyopathy
- Manage the LVOT obstruction
- Prevent sudden cardiac death
- ICD implantation
- Offer screening
- First degree relatives should be offered ECG and echocardiography
How to manage LVOT and SAM?
- Avoid volume depletion as this worsens LVOT obstruction
- First line: beta blocker or rate limiting calcium channel blocker (eg verapamil)
- Second line: surgical myectomy
- Alcohol septal ablation (alcohol injected directly into the coronary artery causing a small iatrogenic MI to reduce septal thickness)
- Heart transplantation may be required in severe cases
Dilated cardiomyopathy definition
Dilated cardiomyopathy is characterised by dilation and systolic dysfunction of the left and/or right ventricles.
Aetiology of dilated cardiomyopathy
Around 50% of cases are idiopathic but several important associations exist.
- Chronic alcohol consumption
- Genetic (at least 20% are familial)
- Viral infections
- Hypothyroidism
- Peripartum cardiomyopathy
- Chemotherapy (eg doxorubicin, trastuzumab)
Clinical features of dilated cardiomyopathy
- Patients may present with symptoms of heart failure, dyspnoea and thromboembolism
- Or patients may be asymptomatic
Why is it important to rule our chronic alcohol consumption?
Dilated cardiomyopathy that is secondary to chronic alcohol consummation is potentially reversible.
Managment of dilated cardiomyopathy
- Managment of heart failure symptoms
- Anticoaguation
- Some patients may need an ICD or CRT
Pathophysiology of restrictive cardiomyopathy
Restrictive cardiomyopathy involves contraction of atria against stiff, non-dilated ventricles with near normal systolic function.
Stiff ventricles lead to impaired diastolic filling, congestive heart failure and reduced cardiac output.
Causes of restrictive cardiomyopathy
Investigations for restrictive cardiomyopathy
- First line: echo
- Gold standard: endomyocardial biopsy
- CT, MRI and diagnostic angiography are also helpful
- Important to distinguish between constrictive cardiomyopathy and constrictive pericarditis as the latter may be correctable with surgery
Managment of restrictive cardiomyopathy
- Treat the underlying cause
- Anticoagulation
- Treat heart failure
Arrythmogenic right ventricular cardiomyopathy definition
A form of cardiomyopathy that can present with arrhythmia or sudden death.
Genetic mutations in the desmosomes of the cardiac myocyte lead to eventual fibro-fatty infiltration of the myocardium, leading to impaired RV function.
Investigations for Arrythmogenic right ventricular cardiomyopathy
Diagnosis is challenging and requires a combination of ECG changes, echocardiography and cardiac MRI.
ECG shows epsilon wave and T wave inversion on ECG.
Management of Arrythmogenic right ventricular cardiomyopathy
Patients should be treated symptomatically and offered ICDs for the prevention of sudden cardiac death.
Definition of Takotsubo cardiomyopathy
Also known as broken heart syndrome, is thought to be a catecholamine mediated response to severe stress events.
Clinical features of Takotsubo cardiomyopathy
Signs and symptoms may mimic MI but patients have non-obstructive coronary arteries on angiography.
Apical ballooning of the left ventricle is pathognomic on ventriculography.
Managment of Takotsubo cardiomyopathy
Usually self limiting, but there is a risk of death due to arrythmia or ventricular free wall rupture.
Most physicians recommend monitoring in the early stages of treatment with beta blockers and ACE inhibitors.
