Rhythm Recognition.
Sinus, Atrial, Junctional / Nodal,
Ventricular, Blocks, others.
Aims and Objectives.
 To be able to calculate heart rate from ECG.
 To understand features of normal sinus
rhythm.
 To recognise rhythm abnormalities from a
variety of causes.
 To understand rhythms which may need
immediate / emergency action.
Calculating HR.
 1500 / small squares
 300 / large squares
Is it normal sinus rhythm?
 Rate 60 - 100bpm?
 Regular p wave to
each regular QRS?
 Normal P wave
appearance?
 Normal and constant
PR interval?
Sinus Node Rhythms.
Sinus Tachycardia and Sinus
Bradycardia.
 All features of normal
sinus rhythm EXCEPT -
 Rate <60bpm
(bradycardia).
 Rate >100bpm
(tachycardia).
Sinus Arrhythmia.
 Rate 60-100bpm.
 Varies with respiration
(more common
younger).
 Retains all features of
sinus rhythm - except
regularity of QRS
complex.
 Usually cyclical.
Sinus Arrest.
 Time period without
sinus node activation.
 Clear pause in normal
rhythm.
 Often terminated by
escape beat.
 Rhythm before and after
usually normal.
SA Block.
 Blocks occur as a
multiple of the p-p
interval.
 Measure out.
 Non-conducted beat
from normal
pacemaker.
 Rhythm before and
after normal.
Atrial Rhythms.
Premature Atrial Ectopic Beat.
 Premature firing of
atrial cell (faster than
SA node).
 Earlier complex.
 Compensatory or noncompensatory pause.
 Return to normal
rhythm.
Premature Atrial Ectopic Beat
Run of Premature Atrial Beats.
 Can occur in isolation
or short runs.
 Atrial bigeminy /
trigeminy.
 Longer runs should
really be termed as
SVT.
 Symptoms :- Rarely
 Causes :- More often in older pts.
Lung Disease
Stimulants
 Treatment :- Anti-arrhythmia’s
Wandering Atrial Pacemaker.
 Irregularly irregular
rhythm.
 Multiple atrial
pacemakers firing at
own rate.
 Different p wave
morphologies.
 Different p wave
distance from QRS.
 Different QRS rate.
Atrial Tachycardia.
 Ventricular rate
>100bpm.
 Atrial rate 160-250bpm.
 Varying levels of conduction
(1:1, 2:1, 3:1 etc).
 P waves abnormal or not
easily seen.
 Sometimes seen as part of T
wave or QRS.
Atrial Tachycardia.
Symptoms
 Palpitations, which can be skipping,
fluttering or pounding in the chest.
 Chest pressure or pain.
 Shortness of breath & Fatigue
 Fainting, also known as syncope, or nearsyncope.
 Lightheadedness or dizziness
Causes
 Cardiomyopathy
 Chronic obstructive pulmonary disease
 Ischaemic heart disease
 Rheumatic heart disease
 Sick sinus syndrome
 Digoxin toxicity
Treatment
 Depends on the type and severity
 Medications:- anti-arrhythmic drugs
 Radio-frequency catheter ablation (RFA)
 Cryo-ablation
Atrial Flutter.
 Atrial rate 250350bpm.
 Usually regular QRS
(can be variable
conduction).
 Most commonly 2:1
conduction (150bpm
ventricular and
300bpm atrial).
 Classic 'saw tooth'.
Atrial Flutter.
Causes
 MI & Ischaemic Heart disease.
 Hypertension
 Cardiomyopathy (congestive heart failure)
 Mitral valve disease
Symptoms
 Palpitations
 Syncope & SOB
 Angina
 anxiety
Treatment
 Digoxin & Sotalol (lowers ventricular
rate).
 DC Cardioversion
 RF Ablation
 Anti-coagulants:- stroke
Atrial Fibrillation.
 Irregularly irregular
 Fast or slow AV
QRS.
conduction.
 No p waves - atrial rate  Irregular baseline.
>350bpm.
Atrial Fibrillation.
Causes
 Mitral Valve Disease
 Thyrotoxicosis
 Cardiomyopathies
Symptoms
 Often no symptoms
 Light-headedness & dizziness
 Palpitations
 Chest pain
Treatment
 Digoxin & Sotalol (lowers ventricular
rate).
 DC Cardioversion
 AF supression pacemakers
 R-F Ablation - PVI
Junction and AV nodal
Rhythms.
Junctional Premature
Contraction.
 Premature beat
originating from AV
node.
 Maybe antegrade or
retrograde P wave.
 Compensatory / noncompensatory pause
before restoration of
sinus rhythm.
Junctional Escape Beat.
 Failing of normal
pacemaker (SA node).
 Pause in electrical
activity (Sinus arrest).
 Escape mechanism
from further down in
pathway.
 AV node (slower
intrinsic rate).
Junctional Rhythm.
 Rate 40-60bpm (AV
node intrinsic rhythm).
 Regular.
 P wave retrograde,
antegrade or none.
 No SA nodal activity.
 Pacemaker AV node.
 Conduction normal
from this point.
Accelerated Junctional Rhythm.
 Rate 60-100bpm.
 Otherwise maintains
all features of
junctional rhythm.
Junctional Tachycardia.
 Rate >100bpm.
 Maintains all other
features of junctional
rhythm.
AV nodal re-entrant tachycardia.
 Re-entry circuit in the AV
node - abnormal pathway
to ventricle.
 Commonest type of SVT.
 Rate usually 150+bpm.
Ventricular Rhythms.
Ventricular Premature
Contraction.
 Premature firing of a
ventricular cell.
 Ventricles already
depolarised before SA
node impulse
conducted through.
 Wide, bizarre complex.
 No p wave.
 Often normal variant
but can be associated
with ischemia.
Ventricular Ectopic Beat
VE
Bigeminy
Trigeminy
Ventricular Escape Beat.
 Pause in regular
activity (e.g. Sinus
arrest, slow AF).
 Ventricular focus takes
over as an escape
mechanism.
 Wide, bizarre complex.
 Usually followed by
restoration of
underlying rhythm.
Idio-ventricular Rhythm /
Ventricular Escape Rhythm.
 Rate 20-40bpm
(intrinsic ventricular
rate).
 Regular rhythm.
 No p wave.
 Wide abnormal QRS.
 Usually connected to
3rd degree HB.
Accelerated Idio-ventricular
Rhythm.
 Rate 40-100bpm.
 Exactly same features
as ventricular rhythm.
Ventricular Tachycardia.
 Rate 100-200bpm.
 Regular.
 Occasional dissociated
p waves.
 Wide, bizarre QRS.
 LBBB in V1 indicates
RVOT origin (pulse).
 RVOT also associated with
VF (Brugada).
 RBBB in V1 indicates LV
origin (usually no pulse).
Other Features to distinguish VT.
 Capture beats - normal
looking beat.
 Occurs at exactly right
time to be conducted
through.
 VT continues
immediately following.
 Fusion beats combination of sinus
and ventricular beat.
Torsade de Pointes.




Twisting of the axis.
Rate 200-250bpm.
Regular or irregular.
Sinusoidal pattern.
 May revert to VF or
back to SR.
 Associated with
electrolyte
abnormalities.
Ventricular Fibrillation.
 Chaotic ventricular
activity.
 Rapid contraction unable to produce
cardiac output.
 If patient is fine and
awake - it is not.
 Check leads or get
defibs.
Heart Blocks.
First Degree Heart Block.
 Rate depends on
underlying rhythm.
 Regular.
 Prolonged PR interval
>0.2secs.
 Physiologic block in
the AV node.
 Caused by Medication,
vagal stimulation,
disease.
Mobitz I Second Degree HB.
(Wenckebach).
 Rate depends on
underlying rhythm.
 Regularly irregular.
 Increasing PR interval.
 Dropped beat.
 Cycle starts over.
 Diseased AV node with
long refractory period.
Mobitz II Second Degree HB.
 Rate depends on
underlying rhythm.
 Same PR interval for all
conducted beats.
 P waves usually regular.
 Some p waves not
conducted.
 Can be 2:1, 3:1, 4:1 etc.
 Usually progresses to
CHB.
Complete Heart Block (3rd
Degree HB).
 Atrio-ventricular
dissociation.
 Regular p waves.
 Regular QRS.
 No relationship.
 Rate depends on
intrinsic rhythm (e.g.
escape rhythm).
 Needs pacemaker.
Other rhythms.
Asystole.




No cardiac activity.
Check leads.
Resuscitation.
Chest compressions may
cause ECG waveforms.
 Important to stop to assess
rhythm.
 Usually poor prognosis.
 Check for p waves - may
respond to pacing.
Paced Rhythm.
 Pacing spike.
 Single / dual chamber.
 Bi-ventricular.
 Implantable
defibrillator.