ECG3

16/12/2008 ECG Diag 3/ghazi

Principles of ECG Diagnosis3

Supraventricular Arrhythmias

Dr Ghazi Radaideh, MD, FRCPRashid Hospital

Dubai - UAE


Things to Consider When Analyzing Arrhythmias

Arrhythmias may be seen on 12-lead ECGs or on strips of one or more leads.

Some arrhythmias are obvious at first glance and don't require intense analysis. Others, they require detective work and logical thinking based on a knowledge of cardiac electrophysiology.


Reading 12-Lead ECG step-by-step (RAWIHI)

1. Rate, Rhythm and Regularity2. Determine the QRS Axis3. Evaluate the Waves (P,QRS,T ) and

Intervals (PR,ST,QT)4. Evaluate for chamber Hypertrophy5. Look for myocardial Infarction and Ischemia6. Interpret the ECG


Supraventricular Arrhythmias They are called

supraventricular arrhythmias because they originate in and involve structures above the ventricles.

Arrhythmias

Ventricular

Supraventricular


Supraventricular ArrhythmiasObjectives:1.Sinus Rhythm2.Escapes& Premature atrial complexes 3. Atrial tachycardia & Multifocal atrial tachycardia 4.Atrial fibrillation 5.Atrial flutter 6.SVT (AVNRT, AVRT)7.Junctional rhythms and tachycardias


Normal Sinus Rhythm (NSR) The electrical impulse is formed in the SA

node and conducted normally.


Normal Sinus Rhythm Parameters

Rate 68 (Normal60 - 100 bpm) Regularity regular P waves normal PR interval 0.16 (0.12 - 0.20 s) QRS duration 0.08 (0.04 - 0.12 s)Any deviation from above is sinus tachycardia,

sinus bradycardia or sinus arrhythmia


Bradycardia

the normal sinus rhythm slows.


What is the ECG diagnosis?

30 bpm Rate? Regularity? regular

normal

0.10 s

P waves? PR interval? 0.12 s QRS duration?

Sinus bradycardia


Tachycardia

the normal sinus rhythm fasts.


What is the ECG diagnosis?


normal

0.08 s

P waves? PR interval? 0.16 s QRS duration?

Sinus tachycardia


Sinus ArrhythmiaVariations in heart rate from beat to beat that are greater than would be expected from normal respiratory variation.


Escapes When the dominant pacemaker( SAN) fails

to discharge, an escape beat arises from special sites(Subsidiary pacemakers) within the conduction system. Slow and protective rhythms

sites and rate of escapes sinoatrial node region = 70 per minute. junctional region= 50 per minute.ventricular focus= 30 per minute.


Atrial Escape Complex P wave that occurs later than would be

expected from the sinus rate( SLOWER THAN THE BASELINE RATE)

If the focus is away from the sinoatrial node the P wave will be abnormal, but followed with a normal QRS complex and T wave.


Premature Atrial Contractions Deviation from NSR

These ectopic beats originate in the atria (but not in the SA node),

the contour of the P wave, the PR interval, and the timing are different than a normally generated pulse from the SA node.


Premature Atrial Contractions

Single Double


Premature Atrial Contractions

Bigeminy


Wandering pacemaker.

Consequently, the P-waves will vary in polarity, and the PR interval will also vary.

The origin of the atrial contraction may also vary or wander.


Atrial tachycardia Typically arises from an ectopic source in the atrial

muscle: Atrial rate of 150-250 beats/min. The P waves may be abnormally shaped depending

on the site of the ectopic pacemaker The ventricular rate depends on the degree of

atrioventricular block. Increasing the degree of block with carotid sinus massage

or adenosine may aid the diagnosis.


Atrial tachycardia Parameters

190 Rate of R? Regularity? Regular regular

Abnormal

0.08 s

P waves? P to R ratio? 1:1 QRS duration?Interpretation? AT with 1:1 conduction


Atrial tachycardia with AV block


Multifocal Atrial Tachycardia (MAT)and rhythm

Multifocal atrial tachycardia occurs when multiple sitesin the atria are discharging


Multifocal Atrial Tachycardia (MAT)


Atrial Fibrillation

Atrial activity is poorly defined; may see course or fine undulations or no atrial activity at all.

Atrial Fibrillation


Atrial fibrillation Parameters

140 bpm Rate? Regularity? irregularly irregular

none

0.06 s

P waves? PR interval? none QRS duration?


AF with rapid ventricular response : (note : irregularly irregular rhythm)


Atrial Flutter

Sustained by a macro-reentrant circuit in the lower Rt. atrium.


Atrial flutter Parameters


flutter waves

0.06 s

P waves? PR interval? none QRS duration?


Atrial flutter with 2:1 ratio


PSVT Parameters

74 148 bpm Rate? Regularity? Regular regular

Normal none

0.08 s

P waves? PR interval? 0.16 s none QRS duration?


AV Nodal Reentrant Tachycardia (AVNRT):

The retrograde P wave is often simultaneous with the QRS and, therefore, not seen on the ECG.


1. Orthodromic AVRT

Orthodromic AVRT


2.Antidromic Tachycardia


Antidromic AVRT

Antidromic AVRT


AV Junctional Dysrhythmias

if the SA node does not fire or is blocked, escape mechanisms of the AV junction and ventricle are part of the system.

Junctional dysrhythmias originate in the AV junction The impulse is conducted

differently than SA and retrograde conduction may be seen.


Junctional Escape Beats(nodal escape Beats)

Junctional dysrhythmiasoriginate in the AV junction

.

The beat after the delay will show no P wave (either due to an absence of atrial contraction or because it is partially lost within the QRS complex) .


AV Junctional Rhythm This is a sequence of 3 or more junctional

escapes. With the junctional rhythm, the AV junction

is the pacemaker controlling the heart rate


Parameters of AV Junctional Rhythm

Rate: 40 - 60beats Rhythm: Regular P wave: Inverted. Appears either before,

after, or during the QRS. PR interval: < 0.12 sec if seen before the QRS. QRS : Normal


Accelerated AV Junctional Rhythm

If the rate of junctional rhythm is 60-100 b/m is called accelerated junctional rhythm


Accelerated junctional rhythm


Tachyarhythmias

Narrow complex Wide complex

Regular Irregular Regular Irregular

STATSVTAFL

AFMATAFL /AT with variable AV conduction

VTSVT With abberantconduction

AF with accessory pathway

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