ECG interpretation - arryhthmias, BBB etc Flashcards
(130 cards)
List the main supraventricular arryhthmias
Supraventricular tachycardia:
- Atrial Fibrillation
- Atrial Flutter
- Ectopic atrial tachycardia
Bradycardia:
- Sinus bradycardia
- Sinus pauses
List the main ventricular arryhthmias
- Ventricular ectopics or Premature Ventricular Complexes (PVC)
- Ventricular Tachycardia (VT)
- Ventricular Fibrillation (VF)
- Asystole
List the main AV node arryhthmias
AVN re-entry tachycardia (AVNRT)
AV reciprocating or AV Reentrant tachycardia (AVRT)
AV block:
- 1st degree
- 2nd degree
- 3rd degree
List the clinical causes of arryhthmias
Abnormal anatomy:
- left ventricular hypertrophy
- accessory pathways
- congenital HD
Autonomic nervous system (ANS):
- Sympathetic stimulation: stress, exercise, hyperthyroidism
- Increased vagal tone causing bradycardia
Metabolic:
- Hypoxia: chronic pulmonary disease, pulmonary embolus
- Ischaemic myocardium: acute MI, angina
- Electrolyte imbalances: K+, Ca 2+, Mg2+
Inflammation: viral myocarditis
Drugs: direct electrophysiologic effects or via ANS
Genetic: mutations of genes encoding cardiac ion channels e.g. the congenital long QT syndrome
What are the common symptoms of arryhthmias ?
- Palpitations, ”pounding heart”
- Shortness of breath
- Dizziness
- Loss of consciousness; ”Syncope”
- Faintness: “presyncope”
- Sudden cardiac death
- Angina, heart failure
What are the 1st line investigations to be done on someone presenting with a possible arryhthmia ? (will commonly present with palpatations)
- 12-lead ECG:
- TFT’s - thyrotoxicosis may precipitate atrial fibrillation and other arrhythmias
- Urea and electrolytes: looking for disturbances such as a low potassium
- FBC
- CXR
First-line investigations are often normal in patients complaining of palpitations. The next step is to exclude an episode arrhythmia, what investigations should now be done ?
Most commonly a 24hr Holter ECG is done - patients are asked to keep a diary to record any symptomatic palpitations. This can later be compared to the rhythm strip at the time of the symptoms
Others which may be done include:
- Excercise ECG
- Electrophysiological study
What is the characteristic sign seen on ECG suggestive of WPW syndrome ?
Slurred upstroke (delta wave)

What does an excericse ECG allow you to assess?
- To assess for ischaemia
- Exercise induced arrhythmia
What does echocardiography allow you to assess?
Assess for structural disease of the heart e.g:
- Enlarged atria in AF
- LV dilatation
- Previous MI scar, aneurysm
What is able to be done at the same time of studying the arryhthmia on electrophysiological study ?
Opportunity to treat the arrhythmia by delivering radiofrequency ablation to extra pathway
When analysing the rhythmn of an ECG what are the 6 steps you should analyse?
- Is there electrical activity?
- Is the rhythm regular or irregular?
- What is the HR?
- Are the P-waves present?
- What is the relationship between the P and QRS complexes?
- What is the QRS duration?
How do you determine if there is normal sinus rhythm on an ECG ?
Check there is a p wave for every QRS complex and that the PR interval is < 200ms
How do you determine if an arryhthmia is supraventricular or ventricular in origin ?
- A supraventricular arryhthmia has a narrow QRS complex
- A ventricular arryhthmia has a broad QRS complex (>120ms)
What is shown in this ECG and explain if it is a problem or not

Normal sinus arryhthmia - it is normal and caused by Inspiration reducing vagal tone and increasing HR.
Define what sinus bradycardia is
rate < 60 beats/min (pwaves and QRS complexes normal)
What are the causes of sinus bradycardia ?
- Physiological i.e., athlete
- Drugs (B-Blocker)
- Ischaemia : common in inferior STEMIs
What is the treatment of sinus bradycardia ?
- If asymptomatic & rate >40bpm then no treatment, but stop causative factors e.g. drugs.
- If symptomatic or rate is <40bpm 1st line = IV atropine
- 2nd line = temoprary cardiac pacing required if haemodynamic compromise: hypotension, CHF, angina, collapse
Define a sinus tachycardia
HR > 100 beats/min (note the p wave and QRS are both normal)
What are the causes of sinus tachycardia ?
- Physiological (Anxiety, fever, hypotension, anaemia, excerise, stimulants e.g. caffeine, nicotine etc)
- Inappropriate (drugs, etc)
What is the treartment of sinus tachycardias ?
Treat underlying cause /lifestyle changes +/- Beta-blockers
What are the 3 types of AF?
- Paroxysmal - lasts < 48hrs, often recurrent
- Persistent - lasts > 48hrs but is able to be cardioverted back to normal sinus rhythm (unlikely to spontaneously revert to NSR)
- Permanent (chronic) - Inability of pharmacologic or non-pharmacologic methods to restore NSR
What are the 3 ways in which AF may be terminated and reverted back to normal sinus rhythm (NSR)?
- Pharmacologic cardioversion with anti-arrhythmic drugs (30% effective)
- Electrical Cardioversion (90% effective) by direct current (DCCV)
- Spontaneous reversion to sinus rhythm
List the possible causes of AF
- Hypertension
- Congestive heart failure
- Sick sinus syndrome - ‘tachy brady syndrome’
- Coronary heart disease
- Obesity
- Thyroid disease
- Familial
- Cardiac Valve disease
- Alcohol abuse
- Congenital heart disease
- Cardiac surgery
- COPD, Pneumonia,
- Septicaemia,
- Pericarditis, tumors
- Vagal cause – high endurance athletess

