24. Cardiac Arrhythmias Flashcards
What does this ECG show?
Normal ECG.
What are some features of a normal ECG?
What are some values of a normal ECG? (HR, PR interval, QRS duration, QT, QTc).
What angles are leads II, avF, avR and III looking at the heart from?
What is heart block?
+ve P in lead II. -ve P in avR. Biphasic P wave in V1. Septal Q waves.
HR: 50-90bpm. PR interval: 120-210ms. QRS: <110ms. QT: <420ms. QTc: <440ms.
II: +60o, III +120o, avF: +90o, avR -120o. Any impulse going to electrode is +ve.
Disease/inherited condition causing a fault within the heart’s natural pacemaker due to some kind of obstruction (“block”) in its electrical conduction system.
What is first degree heart block?
What is second degree heart block (2 types)?
What is a third degree heart block?
Long PR interval. Blockage in AVN but only prevents impulse transmitting at normal speed so delay = prolonged PR interval. HR can be normal and it usually regular.
Not every P wave leads to QRS.
1) Mobitz type I (Wenckebach) progressive prolongation of PR until QRS drop
2) Mobitz type II - regular QRS drop. Intermittent non-conducted P waves without progressive prolongation of the PR interval.
HR can be normal and often not regular.
No P wave leads to QRS. Complete heart block. Atrial and venous electrical activity entirely independent. Escape rhythm originates lower down conduction path (nodal/idio-ventricular rhythm). HR regular and nearly always slow.
What does this ECG show?
1st degree heart block.
What does this ECG show?
2nd degree heart block, Type I Mobitz.
What does this ECG show?
2nd degree heart failure, Mobitz type II
What does this ECG show?
3rd degree heart block.
Define arrhythmia (dysrhythmia).
What are the different types of patterns (4 categories)?
Normal regular cardiac rhythm becomes irregular, too fast or too slow. Some awareness of heart beats, or dizziness/faint, or cardiac arrest/sudden cardiac death. ECG is diagnostic test: establish the dx and define type of arrhythmia.
1) Sinus: sinus tachy/sinus brady/irregular (sinus arrhythmia - PP varies over 120ms).
2) Atrial: tachycardia/fibrillation/flutter
3) Junctional: SVT - AVNRT (nodal rentry tachy) and AVRT
4) Ventricular: tachycardia/fibrillation
What does this ECG show?
Check: P wave? Yes. Q wave following each P? Yes. HR = 110bpm. Thus sinus tachycardia.
What does this ECG show?
Sinus bradycardia. HR = 50bpm
What does this ECG show?
Sinus arrhythmia
What does this ECG show? HT for a long time.
No P waves. Flutter waves on rhythm strip = atrial flutter. Waves conducted irregularly down to ventricle.
What does this ECG show? SOB (HT and hypothyroidism)
P waves? No. Lots of baseline disturbance, no clear flutter waves. QRS complexes irregular. Atrial fibrillation.
What does this ECG show? Sudden onset palpitations
Ventricular arrhythmia always broad. Atrial arrhythmia always narrow unless BBB. P waves? No. Supraventricular tachycardia e.g. AVNRET. Not AF (always irregular).
What does this ECG show? (exercise ECG)
Ventricular tachycardia
What does this ECG show? 24 hour ECG recording, single lead.
Ventricular tachycardia
VT or SVT with aberrant conduction?
SVT with aberrant conduction b/c van see LBBB pattern.
VT or SVT with aberrant conduction?
VT. Regular tachycardia, broad QRS, extreme axis deviation.
Distinguish between VT and SVT + aberrant conduction with:
a) age
b) known heart disease
c) ECG BBB pattern
d) AV dissociation
e) QRS duration
f) QRS axis
g) QRS morphology (inital vector)
What are some ECG factors suggestive of VT?
Absence of typical RBBB/LBBB morphology. Extreme axis deviation. V broad complexes (>160ms). AV dissociation (P and QRS at different rates). Fusion/capture beats - a hybrid QRS/conducted complex. +ve/-ve concordance throughout the chest leads i.e. V1-6 show entirely +ve (R) or entirely -ve (QS) complexes.
What are the following, and where are they seen?
What if you can’t tell if it’s VT or SVT + aberrant conduction from the ECG?
Top - capture beat. Bottom - fusion beat. Seen in VT.
Treat as VT
