Arrythmias Flashcards
How long is the PR interval in sinus rhythm?
0.12->0.2s
How long is the QRS complex?
0.08s
abnormal considered >0.12s
How long is the QT interval?
Varies with HR but at 60BPM ~0.42 seconds
What is sinus bradycardia/Sinus tachycardia and how are they treated?
Normal rhythm but slow or fast (<60BPM or >80BPM) in a healthy adult
Sinus Bradycardia:
B1 receptor agonist - Isoprenaline - Short Term
Pacemaker - Long Term
Sinus Tachycardia: Internal Defribillator
What is Sinus Arrest?
A pause in the heart beat with no waves at all
Usually misses atleast 2 beaths
Underlying rythm is usually slow and irregular sinus rythm
What is an escape beat?
The first beat after a sinus arrest, its triggered by a abckup pacemaker so is slightly out of sync but then the SA takes over agian
What is (Broad Complex Tachy) Ventricular Tachycardia and what causes it?
A very high but regular Heart Rate
Ventricular cells are irritated or scarred causing them to fire independantly of the normal conduction and rapidly
How does ventricular tachycardia (broad Complex Tachy) present, ECG and whats the danger?
Palpitations - Syncope - Lightheadedness - sOB - Angina
ECG: Hr >120BPM - Broad QRS complex - often 3 wide QRS between P waves
- Can devolve into Vfib
What is Vfib?
Ventricles quivering instead of contracting
HOw does vfib manifest clinically and on ECG?
Cardiac arrest - syncope - no pulse - no breathing - angina - cyanosis - naeusea
Irregular unformed QRS and no p waves
What are the indications for ICD?
Secondary Prevention:
- Cardiac arrest due to VF/VT
- Sustained VT -> syncope or significant compromise
- Sustained VT with poor LV function
What is supraventricular tachycardia?
Tachycardia starting at or above the AV node
Present with palpitaions - anxiety - chest pain - dizziness - SOB
Supraventricular ectopic beats - Afib - Aflutter - W-P-W
What is Wolff-Parkinson-White syndrome?
A type of supraventricular tachycardia of the AV re-entrant type:
A short P-R interval with a slow rising R wave.
Due to:
An extra accessory pathway bypassing the AV node straight to the ventricles, thus signal travels faster thugh the accessory pathway so the ventricle is triggered faster (short P-R) and for a longer time (slow rising R wave).
Can slip into a re-entry circuit causing tachycardia
What is Atrial Flutter?
A supraventricular Tachycardia caused by one of the backup pacemakers going wrong and firing way above the SA node at 250-300BPM, because the AV node has a delay the ventricles will contract closer to 150BPM.
How does Atrial Flutter appear on an ECG?
Saw tooth P wave going v fast.
V high QRS rate but regular
What is Afib?
A type of supraventricular tachycardia. Abnormal electrical activity in atria leads to random atria spasming & random irregularly irregular AV node stimulation
HOw does afib appear on an ECG?
NO distinct p waves
Irregularly Irregular QRS complexes (rapid)
What other tests can be done for Afib?
Bloods - Esp TFTs
Echo - Quivering Atria
Pulse - Rapid and irregularly iregular
How does Afib present?
Fatigue Palpitations SOB Angina Oedema Emboli -> Stroke
How do we treat Afib?
Rate Control:
Class 2, 4 and 5 anti-arrthmics - B blockers (atenolol), RL CCBs and Digoxin
Rhythm Control:
Electrical Cadioversion
Chemical Cadioversion (Class 1c Flecainide {Na blocker} and 3 Amiodarone {Prolongs refractory})
Anti-Coagulants:
Aspirin + clopidogrel and warfarin to prevent emboli
What is 1st degree heart block?
A P-R interval over 0.2 seconds (5 small squeres)
What could you see on an ECG in severe type 1 Heart block?
P wave buried in previous T wave
Describe the 2 types of 2nd degree AV block, the problem and the treatment?
Mobitz 1:
- Progressive P-R prolongation culminating in a non-conducted P wave (skipped QRS)
- Malfunctioning AV node
- Treat with Atropine
Mobitz 2:
- Intermittant non-conducted P waves with no prolongations
- Worse than Mobitz 1
- Problem below AV node
- Treat with a pacemaker
What is a fixed ratio block?
Shown in type 2 AV block
blocks of a fixed ratio of P-QRS waves
Describe 3rd degree heart block?
Complete AV block
Both P waves and QRS are reuglar but unrelated
May include ventricular standstill
Usually develops at the end point of 2nd degree
Treat with Atropine and Pacemaker
What is Polymorphic Ventricular Tachycardia?
Ventricular Tachycardia where multiple ventricular foci causing the QRS complexes to be varied in amplitude, axis and duration
The commonest Cause is Myocardial Ischaemia
What is Torsades De Pointes?
A specific type of Polymorphic Ventricular Tachycardia in the context of QT prolongation.
How does torsades de pointes appear on an ECG?
PVT and QT prolongation appearing like massive QRS complexes twisting around the central line.
Like the Arctic monkeys album cover
How does Torsades de Pointes present and whats it treated with?
Usually its short lived and self-limiting but it can devolve into Vfib
It presents haemodynamic instability and collapse.
