Cardiac Myopathies & Channelopathies Flashcards
What is a cardiomyopathy?
A problem with heart muscle
What types of congenital heart defects are there?
Structural
Cardiomyopathies
Channelopathies
All cardiomyopathies will present themselves within the first few years of life. True or false?
False!
They can start to develop at any age.
Some people have no abnormalities for many years and suddenly one starts to manifest itself
Who do we screen for congenital heart defects?
People who have affected first degree relatives
Groups at risk of mortality: athletes
List some cardiomyopathies.
Hypertrophic
Dilated
L ventricle non-compaction
Arrhythmogenic
Describe some other non heart specific conditions that can cause CVS diseases.
Palmoplantar keratoderma
Marfan’s syndrome:
Can cause an aortic root aneurysm
Familial Hypercholestrolaemia:
Can’t take up cholesterol from blood due to an LDL receptor fault. Excess blood cholesterol = heart problems
List some Channelopathies.
Long QT
Short QT
Brugada
CPVT
What are the features of hypertrophic cardiomyopathy?
Thick walls, small cavities
When they contract the atria & ventricles contract down to almost nothing
Disorganised arrangement of myocytes
Fibrotic tissue develops: arrhythmias
Why does fibrotic tissue cause arrhythmias?
Fibrotic tissue is an electrical insulator, so it blocks electrical conduction in the heart.
Causes random bursts of ventricular arrhythmias
How do patients with hypertrophic cardiomyopathy present?
Sudden death Angina Dyspnoea Palpitations Syncope Jerky pulse Harsh ejection systolic murmur
What tests can you do to confirm hypertrophic cardiomyopathy?
ECG: shows up the random bursts of ventricular arrhythmia
Echo: shows up the hypertrophic walls
Exercise test with heart monitor
What is the treatment of hypertrophic cardiomyopathy?
Beta blockers or verapamil (a Ca antagonist): to reduce ventricular contractility
Amiodarone: anti-arrhythmic drug
Anti-coagulants: to prevent a clot forming as a result of arrhythmia
Septal myomectomy
Implantable defribrillator
What is septal myomectomy? How is it done?
Removal of a portion of the septum that is obstructing the flow of the blood from the ventricle to the aorta
Can be done surgically or chemically (alcohol ablation)
What is an implantable defibrillator?
A device placed in the heart that senses and corrects any arrhythmias that occur
It corrects them by giving electric shocks to get the heart back into a normal rhythm
Which type of cardiomyopathy causes the most sudden deaths?
Hypertrophic
What are the features of dilated cardiomyopathy?
A dilated, flabby heart
Thin walls
Chambers don’t contract properly
How do patients with dilated cardiomyopathy present?
They present very young with heart failure
Breathless
Fatigue
Fluid retention
Emboli
What are the clinical signs of dilated cardiomyopathy?
Raised pulse Low BP Raised JVP S3 gallop Mitral or tricuspid regurgitation Pleural effusion
What tests can you do to confirm dilated cardiomyopathy?
Bloods:
Look for B-natriuretic peptide which will be raised
U&E: low Ca2+
CXR: cardiomegaly, pulmonary oedema
ECG: tachycardia
Echo: flabby, dilated heart
What is the significance of low Ca2+ in dilated cardiomyopathy?
Low Ca2+ indicates a poor prognosis
What is the treatment of dilated cardiomyopathy?
Bed rest
Diuretics
Digoxin: cardiac stimulant
ACE inhibitors
Anti-coagulants
Transplant
What are the features of left ventricle non-compaction?
The inside of the heart is sponge like during development and is compacted prior to birth to leave chambers
In this condition there’s a fault in the compaction process and the inside of the heart, especially the L ventricle remains spongy and there are excessively prominent trabeculations
This causes poor pumping performance
How do patients with left ventricle non-compaction present?
Heart failure symptoms SOB Oedema Fatigue Exercise intolerance
Tachycardia
Blood clot formation
How is left ventricle non-compaction diagnosed?
When the trabeculations are more than twice as thick as the underlying ventricular wall
What tests can you do to confirm left ventricle non-compaction?
Echo CT PET MRI to look at the trabeculations
What is the treatment of left ventricle non-compaction?
ACE inhibitors
B-blockers
Aspirin
Implantable pacemaker
Heart valve replacement
Heart transplant
What is palmoplantar keratoderma?
A syndrome causing abnormal thickening of palms and soles when there is minor trauma
It also causes cardiomyopathy: fibro-fatty replacement of the right ventricle
Fibro-fatty tissue causes arrhythmias
What is a channelopathy?
Disturbed function of ion channels or the proteins that regulate them
Cardiac Channelopathies appear normal on a scan but abnormal on ECG
What are the features of long QT?
There are a few different forms
Q - T segment is longer than it should be
You get random bursts of ventricular arrhythmias
What can cause a cardiac arrest in patients with Long QT?
Stress
Sudden noise
Strenuous exercise
Slow HR during sleep
Drugs: a huge list of drugs that can trigger a cardiac arrest
What is the pathophysiology of Long QT?
Flow of ions in and out of cardiac myocytes generates the heart’s electrical activity
In Long QT flow of potassium ions out of cardiac myocytes is delayed
This means that after each heartbeat the heart takes longer to repolarise (reset itself)
What are the causes of Long QT?
Inherited
Drug induced
Anorexia: due to dangerous electrolyte imbalances
Which gender is more commonly affected by Long QT?
Females
What are the symptoms of Long QT syndrome?
Sudden death
Asymptomatic
Blackouts
Seizures
Arrhythmia: torsade de pointes
Ventricular fibrillation
What is torsade de pointes arrhythmia?
A type of arrhythmia that can lead to sudden cardiac arrest
It is a ventricular tachycardia
What is ventricular fibrillation?
Why is it so dangerous?
Uncoordinated contraction of the cardiac muscle of the ventricles
The heart quivers rather than contracts
This means that the heart can’t pump blood around the body properly as there’s no contraction occuring
What is the treatment for Long QT?
Drugs: B-blockers
Implantable cardioverter-defibrillator (ICD) that can detect and correct arrhythmias
Avoid trigger: strenuous exercise, loud noises
Investigations of Long QT?
ECG
History: syncope, blackouts etc.
Family history of Long QT, sudden death
What are the features of short QT?
QT segment is shorter than it should be
Abnormal heart beat
V-fib
What are the symptoms of short QT?
Palpitations
Unexplained syncope
V-fib
Sudden death
What is the pathophysiology of short QT?
Increased activity of K channels in cardiac myocytes, so K ions flow out of the cells quicker than they should
This alters the electrical activity of the heart
What causes short QT?
Inherited genetic mutations
What is the treatment for short QT?
Implantable cardioverter-defibrillator (ICD)
Detects and corrects arrhythmias
Anti-arrhythmic agents: quinidine
Investigations of Short QT?
ECG
History of blackouts etc.
Family history
What are the features of Brugada Syndrome?
Arrhythmias caused by problems with the electrical activity of the heart
What are the symptoms of Brugada Syndrome?
Blackouts Seizures Heart palpitations V or A-fib Sudden death
Which type of people are mot affected by Brugada Syndrome?
Males
Young and middle age
Japanese & SE Asian descent
What is the pathophysiology of Brugada Syndrome?
Genetic mutations that cause problems with ion channels in the heart, which causes problems with heart contraction
There are a few mutations that cause Brugada, one of which reduces the flow of sodium ions into the cell
Investigations of Brugada.
ECG: does not always show up problems, need to give a drug that will help to show up the problem
Genetic testing
What drug can be used to show up problems on an ECG when diagnosing Brugada? How does it work?
Ajmaline: an anti-arrhythmic
It blocks sodium channels
It will show up any abnormalities of heart electrical activity on an ECG
How do you treat Brugada?
ICD pacemaker
No drugs available
Avoid triggers: fever, diarrhoea, many more
What does ICD pacemaker stand for?
Implantable cadioverter defibrillator
What does CPVT stand for?
Catecholaminergic polymorphic ventricular tachycardia
What are the features of CPVT?
Ventricular tachycardia that arises during times when they have high adrenaline levels (catecholaminergic)
Can cause fainting or sudden death
What are the symptoms of CPVT?
Associated with exercise, emotion, things associated with high adrenaline levels
Syncope
Blackouts
Seizures - if V tachycardia persists
If it persists further, V-fib can develop
Sudden death
Investigations for CPVT.
ECG is not helpful on its own
Stress test: stress the heart using exercise or catecholamines
This will show up premature ventricular contractions which can sometimes progress into ventricular tachycardia
What is polymorphic ventricular tachycardia?
A form of ventricular tachycardia where there are QRS complexes varying in amplitude, axis and direction
With the Channelopathies, how come sometimes only syncope occurs and other times death occurs?
When the heart goes into ventricular tachycardia, sometimes it corrects itself and the heart goes back to normal sinus rhythm
Sometimes it doesn’t and the heart goes into V-fib and can’t usually get out of this without medical intervention
This is when death occurs
