ECG Made Easy - Chapter 3 - The Rhythm of the Heart

benryan95's version from 2015-09-14 15:02

Section 1

Question Answer
What does sinus rhythm mean?Depolarisation begins in the SA node
Where can abnormal cardiac rhythms start?The atrial muscle, the region around AV node (junctional), the ventricular muscle
Are QRS complexes normal in atrial rhythms?Yes
Are QRS complexes normal in junctional rhythms?Yes
Are QRS complexes normal in ventricular rhythms?No, they have wide QRS complexes
What are escape rhythms?If the rate of depolarisation of SA node slows down, or can't reach the rest of the myocardium, a focus somewhere else takes control - is a delayed beat
What is different on an ECG between nodal(junctional) escape and atrial escape?nodal escape has no P waves, atrial escape has abnormal p waves
Can ventricular escape beats be single?Yes
In ventricular escape, are p waves regular?Yes
In ventricular escape, how do the QRS complexes change?Abnormal shape and wider

Section 2

Question Answer
What is an extrasystole?When a part of the heart depolarises earlier than it should
In atrial extrasystoles, describe the P waves?Abnormal
In junctional extrasystoles, describe the P waves?Absent (or appears immediately before or after the QRS complex
In ventricular extrasystoles, describe the QRS complexesTypically wide, of almost any shape (can be common and of no importance)
What can happen when a ventricular extrasystole starts early in the T wave of a preceding beat?They can induce ventricular fibrillation
What does it mean if an early QRS complex follows an early P wave?Atrial extrasystole
What does it mean if the P wave after an extrasystole appears later than expected?It is a supraventricular extrasystole

Section 3

Question Answer
What does performing carotid sinus pressure do?Activates reflex that leads to vagal stimulation of SA and AV nodes - therapeutic effect on supraventricular tachycardias
What happens in atrial tachycardia, if the atria contract higher than 200bpmAV block, AV can't conduct, QRS complex doesn't follow p wave
What is atrial flutter?When atrial rate is greater than 250bpm and there is no flat baseline between the P waves
How could you distinguish between atrial tachycardia and junctional tachycardia?Presence of p wave indicates atrial tachycardia
Describe the QRS complex in atrial tachycardiaNormal
Describe the QRS complex in junctional tachycardiaNormal
Describe the QRS complex in ventricular tachycardiasWide and abnormal in all 12 leads
Describe what could be seen in ventricular tachycardiano P waves, regular but tachycardic QRS complexes, broad QRS complex with abnormal shape, no visible T waves
Does infarction make ventricular, or supraventricular tachycardia more likely?Ventricular

Section 4

Question Answer
Describe what is seen in atrial fibrillation on an ECGno P waves, irregular baseline, irregular QRS complexes, normal QRS complexes
What is Wolff-Parkinson-White syndromeWhen an extra/accessory conducting bundle is present between atrium and ventricles (usually on the left side)
What is seen on a WPW syndrome ECG?short PR interval, slurred upstroke of QRS complex (delta wave) - and perhaps right axis deviation?
WPW can cause paroxysmal tachycardia. What does this mean?A circuit is set up in the heart, depolarisation goes down then back up again, sustained tachycardia with no P waves
What does carotid sinus pressure do to most tachycardias?Slow rhythm
What does carotid sinus pressure do in atrial fibrillation and ventricular tachycardia?Nothing
What can be seen in an ECG with a pacemaker?p waves not related to QRS complexes, QRS complexes preceded by brief spike (pacemaker stimulus), broad QRS complexes

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