Rhythms Flashcards
What are the features of Sinus Rhythm?
P wave followed by QRS complex P-waves: Present and upright Rate: 60-99bpm Rhythm: regular PR Interval:
What defines Sinus Arrhythmia?
P-waves: Present and upright
Rate: 60-99bpm
Rhythm: irregular
PR Interval:
What feature distinguishes bradycardia?
Rate >60bpm
What feature distinguishes Tachycardia?
Rate >100
What is a sinus pause?
Failure of the atria to depolarise for 1-2 beats. Sinus node does not reset and the impulse formed is blocked by the atria.
Describe sinus arrest
Failure of SA node to generate an impulse for >2 cycle lengths; SA node needs to reset.
What is/ are Junctional Escape Rhythm / Beats?
≤2 consecutive QRS complexes from escape pacemaker = junctional beats. ≥ 3 onsecutive QRS complexes from escape pacemaker = junctional rhythm.
Rhythm originating from AV junction escape pacemaker causing Antegrade Ventricular depolarisation and retrograde atrial depolarisation. It appears after the next sinus beat is due.
What are the ECG features of Junctional Rhythm/ Accelerated Junctional Rhythm/ Junctional Tachycardia?
P-waves: absent/inverted/ in QRS Rate: 40-60bpm Rhythm: Regular PR Interval: N/a due to absent P-Waves QRS complex: narrow and normal
What is a super ventricular ectopic?
A narrow looking premature beat originating from a site in the atria or AV node.
Define the ECG features of Supraventricular Tachycardia.
Rate: 140-250bpm
Rhythm: Regular
P-waves: Absent/ hidden in previous T-wave/ Different morphology or configuration.
What does an ECG depicting Atrial Flutter look like?
P-waves: Replaced by saw tooth flutter waves.
Rate: Atrial: 250-400bpm, Ventricular: 60-100bpm
Rhythm: Atrial: Regular, Ventricular: regular/irregular
What does an ECG depicting Atrial Fibrilation look like?
P-waves: Replaced by erratic baseline fibrillatory waves.
Rate: Atrial: >400bpm, Ventricular: Slow 100bpm
Rhythm: irregular
What is a wandering Atrial pacemaker and how does it present on ECG?
Vagal tone decreases SA node activation causing atrial depolarisation to be stimulated by different pacemakers in the atria and AV junction. Pacemaker site generally changes changing P-wave morphology.
P-waves: Differing morphology
Rhythm: Irregular/ regular
What are the ECG features of Idioventricular rhythm?
P-waves: absent/ present if there is AV dissociation
Rate: 20-40bpm
Rhythm: regular/ irregular
QRS: >0.12s - wide and bizarre
Accelerated Idioventricular rhythm = 40-100bpm
What is a Ventricular Ectopic?
Premature beats arising from a ventricular escape pacemaker (bundle branches, Purkinje network, ventricular myocardium)
QRS: >0.12s - wide and bizarre
No P-wave preceding beat.
What is unofficial VE?
VE arrises from the same focus; same morphology
What is a multifocal VE?
Arises from different foci; different morphology.
What is ventricular bi- and tri- geminy?
A VT occurring every 2nd or 3rd beat respectively.
What is Ventricular Tachycardia and what are the ECG Features?
Originates in a ventricular ectopic pacemaker. Is a run of ≥3 VE’s. Sustained VT= >30s; non-sustained VT = VT 0.12s
What is R on T phenomenon?
VE occures in Relative refractory period (Halfway through T-Wave). Can cause VT or VF.
What is ventricular fibrillation?
Asynchronis and rapid ventricular twitching. CO ceases, patient loses consciousness.
What is Ventricular Standstill (Asystole)?
Absence of ventricular contraction. No QRS. P waves may occur at 60-100bpm.
What is Electromechanical Dissociation or Pulseless Electrical Activity?
Any rhythm that appears on ECG but does not produce a pulse.
What are the ECG features of 1st Degree AV Block?
PR interval constant and >0.2s
What are the ECG features of 2nd Degree AV Block, Moritz Type 1 (Wenchebach)?
Lengthening PR interval until conduction fails and a QRS is dropped.
- Count Atrial and Ventricular Rates
- Look at Atrial and Ventricular Rhythms
- Cyclical Rhythm
What are the ECG features of 2nd Degree AV Block, Moritz Type 2?
-Constant PR Interval with a dropped beat.
- Atrial rate and rhythm regular
_ Ventricular rate and rhythm irregular
What are the ECG features of 2nd Degree 2:1 and High degree block?
Atrial rate > ventricular rate. 2:1 = 2 p-waves: 1 QRS. High Degree block = ≥3 p-waves : 1 QRS.
- if P-wave occurs before the T-wave cannot measure QT interval.
What are the ECG features of 3rd degree AV Block?
- Dissociation between SA node and AV node
- Atrial and Ventricular rhythm are regular but independent
- interpretation= sinus rhythm with an atrial rate of….. with junctional rhythm and a ventricular rate of……
- measure p-p interval to check rhythm regularity
What are the ECG Features of Right Bundle Branch Block?
- QRS: incomplete: 0.10-0.11s, complete: >0.12
- Wide rSR’ wave (M shape) V1 - V2 with possible T wave inversion
- V5-V6 qRS with slurred S wave
- Left anterior fascicular block also present if LAD is present
What are the ECG Features of Left Bundle Branch Block?
- QRS: incomplete: 0.10-0.11s, complete: >0.12
- deep wide QRS complexes with slurred S waves V1-V3
- Tall Wide RS, notched at peak. May have T-wave inversion
- ST: N/A due to LBBB
- T-wave: N/A due to LBBB
- QTc: N/A due to LBBB
- Axis: usually LAD
What are the ECG characteristics and the common causes of LAFB?
- ECG Characteristics:
- Left axis
- small +ve R waves in II, III, and aVF
- small q waves in I and aVL
Cause: acute anteroseptal MI
What are the ECG characteristics and the common causes of LPFB?
- ECG Characteristics:
- Right axis
- small +ve R waves in I and aVL
- small q waves in II, III, and aVF
Cause: acute anteroseptal MI involving LAD and either acute right ventricular or inferior MI involving PDA.
