cardiac arrhythmias Flashcards
1
Q
what are arrhythmia’s generally named for
A
- The anatomical site or chamber of origin
- Mechanism or pathway
- includes tachycardia and bradycardia
- Can occurs as single beats or continuously or repeated episodes of limited duration
2
Q
what is an arrhythmia
A
abnormalities in the cardiac rhythm generated by abnormal electrical conduction
3
Q
Supraventricular (SVT)
A
- Origin is above the ventricles anatomically (SAN, atrial myocardium, AV node, HIS origin)
- ECG shows narrow QRS
4
Q
Ventricular Tachycardia
A
- ventricular myocardium (common)
- or fascicles of the conducting system (uncommon)
- The ECG shows a wide QRS as the arrhythmia path is outside the fast His PK system
5
Q
common types of Atrial tachycardia
A
Atrial Fibrillation
Atrial Flutter
Ectopic atrial tachycardia
6
Q
common types of bradycardia
A
Sinus bradycardia
Sinus pauses
7
Q
Ventricular Arrhythmias
A
- Ectopics or Premature Ventricular Complexes
- Ventricular Tachycardia (VT)(>3 beats @ >100bpm)
- Ventricular Fibrillation (VF) (fast chaotic irregular)
- Asystole ( no contractions)
8
Q
causes of arrhythmias
A
-Abnormal anatomy which
allows re-entrant circuits
-Autonimic nervous system
-Metabolic
-Inflammation
-drugs
-genetics
9
Q
Abnormal anatomy which allows re-entrant circuits
A
- Accesory pathways
- Congenital HD
10
Q
Autonimic nervous system
A
- Sympathetic stimulation
- Increased vagal tone = bradycardia
11
Q
Metabolic
A
- Hypoxia
- Ichaemic myocardium
12
Q
Inflammation
A
viral myocarditis
13
Q
drugs
A
direct electrophysiological effect or via ANS
14
Q
genetics
A
mutation of genes coding cardiac ion channels e.g. congenital long QT syndrome
15
Q
‘Heart block’ = AVN block
A
- Means delayed or nonconduction through the AV node
- May be intermittent or permanent
- Varying degrees, described according to the pattern of block
16
Q
First degree AVN block =
A
slow conduction (long PR interval)
17
Q
Second degree =
A
intermittent, PR interval may be varying
18
Q
Complete or third degree=
A
complete nonconduction
19
Q
symptoms
A
- Palpitations, ”pounding heart”, “skipped beat”
- Dyspnoea
- Faintness: “presyncope”
- Transient loss of consciousness; ”Syncope”
- Shock
- Sudden cardiac death
- Angina
- Heart failure
- Anxiety
20
Q
consequences
A
Tachycardia
- may be life-threatning depending on how it affects CO
21
Q
investigations
A
- 12 lead ECG (during SR and in tachycardia ideally)
- Bloods: FBC, Biochemistry, thyroid function
- CXR
- Echocardiogram
- Stress ECG
- Look for myocardial ischaemia, exercise related arrhythmias
- 24-hour ECG Holter monitoring
- Event recorder: (capture the arrhythmia)
- Electrophysiological (EP) study
- catheter inserted, inside of heart
22
Q
Electrocardiogram ECG
A
Recording of cardiac electrical activity from the body surface
To assess rhythm, cardiac conduction system,
Signs of
- pre-excitation (delta waves)
- abnormal repolarization (a prolonged QT interval)
23
Q
Exercise ECG
A
To assess for ischaemia
Exercise induced arrhythmia
24
Q
24hr Holter ECG
A
To assess for paroxysmal arrhythmia
To link symptoms to underlying heart rhythm
25
Echocardiography
To assess for structural heart disease e.g
- Valve disease
- LV, RV dilatation,
- Hypertrophic cardiomyopathy
- Previous MI scar, aneurysm
26
Electrophysiological study
To trigger the clinical arrhythmia and study its mechanism/pathways
Opportunity to treat the arrhythmia by delivering radiofrequency ablation to extra pathway
27
Normal Sinus Arrhythmia
Variation in heart rate, due to reflex changes in vagal tone during the respiratory cycle.
Inspiration reduces vagal tone and increases heart rate
28
Sinus Bradycardia
< 60 beats/min
Physiological i.e., athlete
Drugs (B-Blocker)
Sinus node disease
Channelopathies eg long QT syndrome
29
Treatment if symptomatic or unstable for sinus bradycardia
Atropine (if acute, e.g. acute MI)
Pacing if haemodynamic compromise: hypotension, CHF, angina, collapse
30
Sinus Tachycardia
HR > 100 beats/min
Physiological (Anxiety, fever, hypotension, anaemia)
Inappropriate (drugs, etc)
31
Sinus Tachycardia treatment
Treat underlying cause
B-adrenergic blockers
32
Regular Supraventricular Tachycardia may be due to
- AV nodal re-entrant tachycardia (AVNRT)
- AV reentrant tachycaria (via an accessory pathway) (AVRT)
- Ectopic atrial tachycardia (EAT)
33
Supraventricular Tachycardia acute management
Increase vagal tone: valsalva, carotid massage
Slow conduction in the AVN
IV Adenosine
IV Verapamil
34
Supraventricular Tachycardia chronic management
- Avoid stimulants
- Electrophysiologic study and Radiofrequency ablation (first line in young, symptomatic patients)
- Beta blockers
- Antiarrhythmic drugs
35
What is Radiofrequency Catheter Ablation ? (RFCA)
Selective localised cautery of cardiac tissue to prevent
- tachycardia, targeting either an automatic focus or part of a re-entry circuit
36
AVN Conduction Disease (Heart Block) Causes
- Ageing process
- Acute myocardial infarction
- Myocarditis
- Infiltrative disease
Amyloid, sarcoid
- Drugs
B-adrenergic blockers
Calcium channel blockers
- Calcific aortic valve disease
- Post-aortic valve surgery
- Genetic : Lenegre’s disease, myotonic dystrophy
37
1st Degree A-V Block
Not really “block”, conduction to the ventricles following each P wave but takes longer.
P-R interval longer than normal (> 0.2 sec)
38
2nd Degree AV Block
Intermittent block at the AVN (dropped beats)
39
Mobitz I
progressive lengthening of the PR interval, eventually resulting in a dropped beat.
Usually vagal in origin
40
Mobitz II:
Pathological, may progress to complete heart block (3rd degree HB)
Usually 2:1, or 3:1, but may be variable
Permanent pacemaker indicated
41
types of pacemakers
Single chamber (paces the right atria or right ventricle only)
Dual chamber (paces the RA and RV)
(Implanted under local anesthesia)
42
what is ectopy most likely to be
symptomatic if associated with reduction in BP
43
causes of ventricular ectopics
Structural causes: LVH, heart failure, myocarditis
Metabolic: Ischaemic heart disease, electrolytes
Inherited cardiac conditions e.g. hypertrophic cardiomyopathy
44
management of ventricular ectopics
investigate cause and treat accordingly
- Beta-blockers, Ablation of ectopic focus, AAD
45
Ventricular Fibrillation
Chaotic ventricular electrical activity which causes the heart to lose the ability to function as a pump
46
treatment for Ventricular Fibrillation
Defibrillation, Cardiopulmonary resuscitation
47
VT acute treatment
Direct current cardioversion (DCCV) if unstable.
If stable: consider initial pharmacologic cardioversion with AAD, in meantime prepare for DCCV.
48
Correct triggers for VT
Electrolytes
Ischaemia
Hypoxia
Pro-arrhythmic medications (eg drugs that prolong the QT interval eg., sotalol).
49
Long term treatment for VT
Correct ischaemia if possible (coronary artery disease management , including PCI, bypass surgery)
Optimise CHF therapies.
Anti-arrhythmic drugs to date have been shown to be ineffective and are associated with worse outcomes.
Implantable cardiovertor defbrillators (ICD) if life threatening and high risk of recurrence.
VT catheter ablation.
50
ICD
- Does everything pacemmaker does +
- ICD used for monitoring heart rythmns
