Cardiomyopathy Flashcards
(42 cards)
What is cardiomyopathy?
Cardiomyopathy is a broad term used to describe a variety of issues that result from disease of the myocardium.
What is hypertrophic cardiomyopathy?
Hypertrophic cardiomyopathy (HCM) is a genetic disorder characterised by left ventricular hypertrophy (LVH).
primary form of cardiomyopathy i.e. not in response to other underlying disease e.g. hypertension or valvular disease
Epidemiology of HCM
- Second most common cardiomyopathy (after dilated)
- 0.2% prevalence
- May present at any age
- Most common cause of sudden cardiac death in the young
What is the aetiology of HCM
- Autosomal dominant trait: genetic missense mutation in one of the genes that encode proteins in the sarcomere of heart muscle.
- Beta-myosin heavy chain mutation is the most common
RFs for HCM
- Family history
- Friedreich’s Ataxia (autosomal recessive neurodegenerative disease): patients with Friedreich’s ataxia often develop hypertrophic cardiomyopathy
What happens to the heart in HCM
- Walls get thick, heavy and hypercontractile
- muscles grow larger as new sarcomeres are added in parallel to existing ones.
Which ventricle is most affected in HCM
LV
What happens to the interventricular septum in HCM?
interventricular septum grows larger relative to the other ventricular wall
Consequences of HCM
- Walls take up more room so the cavity is smaller and less able to fill with blood.
- Walls are more stiff and less compliant so can’t stretch to fill with more blood.
- This means less blood is pumped out of the heart - stroke volume is reduced. This can lead to heart failure.
What happens due to the muscle growth of the interventricular septum in HCM
- gets in the way of the left ventricular outflow tract during systole.
- This increases blood velocity through this smaller opening, and pulls the anterior leaflet of the mitral valve toward the septum.
- This further obstructs the left ventricular outflow tract.
As blood is forced through a tiny opening in HCM what happens
crescendo-decrescendo murmur (louder as blood first rushes out, and then softer as less blood moves out).
Why might a patient have a bifid pulse in HCM
two pulses are felt because the mitral valve is moving toward the outflow tract and causing increased obstruction mid-systole.
Issue with thick powerful heart
- Leads to disarray of cardiac myocytes.
- This affects conduction and can lead to arrhythmias.
Overall pathophysiology of HCM
Heart thicker > Becomes hypercontractile > New sarcomeres > LV most affected > Increase O2 demand > Ischaemic tissue > Fast arrythmia
What happens as the interventricular septum gets larger relative to the wall?
Takes up more space > Less blood in Ventricles + Less compliance so less filling > Lower SV > Lower CO > Diastolic HF
Signs of HCM
- Ejection systolic murmum
- Bifid pulse
- S4 sound
- Fast arrhythmias
- Hypertrophy on imaging
Symptoms of HCM
Dyspnoea
Syncope
Chest pain
Dizziness
ECG signs for HCM
left ventricular hypertrophy with progressive T wave inversion and deep Q waves; may also be AF, WPW syndrome, ventricular ectopics, VT
Also do Echocardiogram investigation
Treatment for HCM
- BBs + CCBs
- Anti-arrhythmic medication e.g. amiodarone
- Consider defibrillator if at high risk of arrhythmias
- Anticoagulation: if AF is present as there is higher risk of thrombus formation
Why is digoxin contraindicated in HCM?
Digoxin is contraindicated because it tends to increase force of contraction, which can increase the obstruction.
Complications of HCM
- Left ventricular outflow obstruction
- Heart failure
- Arrhythmias: as there is disarray of cardiac myocytes as well as due to the heart becoming ischaemic
- Sudden death: due to fast arrhythmias
What is dilated cardiomyopathy? (DCM)
all 4 chambers of the heart dilate (but don’t get thicker).
Epidemiology of DCM
- Most common type of cardiomyopathy
- Prevalence: 0.2%
Causes of DCM
- Idopathic
- Autosomal Dominant
- Alcohol
- Infections
- Drugs
- Genetics
