ECG4

ECG Diag 4/ghazi �

Principles of ECG Diagnosis4

ventricular arrhythmias

Dr Ghazi RadaidehMD, FRCP

Rashid HospitalDubai - UAE


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

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

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


Ventricular Arrhythmias1. Premature ventricular complexes (PVCs) 2. Idioventricular rhythm &Accelerated

ventricular rhythms 3. Ventricular tachycardia 4. Differential diagnosis of wide QRS

tachycardias 5. Ventricular Fibrillation6. Asystole


1. Premature Ventricular Complexes (PVCs)

Premature ventricular contractions result from an irritable ectopic focus in the ventricles. This initiates an early beat.

It may be: unifocal, multifocalmultiformed.


Single unifocal PVC


Multifocal PVC

Multifocal PVCs have different sites of origin


Multiformed PVCs• Usually have the same coupling

intervals (because they originate in the same ectopic site but their conduction through the ventricles differ.

•Multiformed PVCs are common in digitalis intoxication.


Bigeminy and Trigeminy

ECG Diag 4/ghazi

Couplets (2 PVCs in a row):


VT after PVC

ECG Diag 4/ghazi ��

Time of PVCs1- early in the cycle (R-on-T phenomenon), 2-after the T wave3- late in the cycle - often fusing with the

next QRS (fusion beat).


R on T Phenomenon


Interpolated PVC.

If a PVC occurs early enough (especially if the heart rate is slow), it may appear sandwiched in between two normal beats


Interpolated PVC


Fusion Beats•The ventricular contraction from the ectopic focus occurs at the same time with the contraction from the beat transmited from the atrium.

This contraction will appear with a P wave but a broad QRS complex and inverted T wave.


Recognizing Aberrant Conduction or PVCs

Aberrant Conduction• Preceding P wave• Initial portion of QRS

identical to conducted beats

• RBBB pattern• No compensatory pause

PVC• No preceding P wave• Monophasic QRS• Big-R, little-R pattern• Compensatory pause


Ventricular Escape Complex

If the sinoatrial node slows down and a focus in the ventricles takes over control of the heart, the beat is described as a ventricular escape complex


Accelerated Ventricular Rhythms

• Ventricular rate 60-100 bpm– Sometimes called isochronic ventricular rhythm

because the ventricular rate is close to underlying sinus rate

• May begin and end with fusion beats• Usually benign,.


Accelerated Ventricular Rhythms


Ventricular Tachycardia

Defined as five or more ventricular ectopic beats in rapid succession.

Signs of myocardial irritability can precede ventricular tachycardia, like frequent PVCs, couplets, or an R on T phenomenon.



160 bpm• Rate?• Regularity? regular

none

wide (> 0.12 sec)

• P waves?• PR interval? none• QRS duration?



• Sustained (lasting >30 sec) vs. nonsustained • Monomorphic (uniform morphology) vs.

polymorphic vs. Torsade-de-pointes • Presence of AV dissociation (independent atrial

activity) vs. retrograde atrial capture • Presence of fusion QRS complexes (Dressler

beats)


Non-sustained VT


Sustained Ventricular Tachycardia


Types and causes of VT • VT with ischemic heart disease ('ischemic VT') • VT with structural heart disease - dilated

cardiomyopathy, HCM, MV prolapse• VT without structural heart disease ('idiopathic VT')• Idiopathic right VT : RVOT origin• Idiopathic left Ventricular Tachy.• Bundle branch reentrant tachy.• Arrhythmogenic right ventricular dysplasia( ARVD) • Long QT syndrome (congenital or acquired)


Torsade de Pointes

a distinctive VT in which the QRS complexes change in morphology from positive to negative and appear to twist around an imaginary base line


Ventricular Fibrillation

none• Rate?• Regularity? irregularly irreg.

none

wide, if recognizable

• P waves?• PR interval? none• QRS duration?


Asystole• Asystole must be confirmed in 2 leads on

the ECG because it may resemble “fine: v-fib”. Always look at a second lead for confirmation.

• Just make sure the leads have not fallen off the patient.


ASYSTOLE


Wide QRS tachycardiaDifferential diagnosis


Wide QRS Complex Tachycardia

• SVT including AF, AFL and AT with preexisting aberrant conduction (BBB)

• SVT including AF, AFL and AT with functional or rate related aberrant cond.

• AF, AFL and AT with AP• Antidromic AVRT• Bundle Branch Reentry• Ventricular Tachycardia


Differential diagnosis of wide QRS tachycardia (1)

Useless guidelines

• Symptoms • Haemodynamic disturbances• Regular rhythm


Differential diagnosis of wide QRS tachycardia (2)

Useful guidelines1. Clinical circumstances2. Independent atrial activity:

A.direct sign - normal P waveB.indirect signs: capture beat and fusion beat

3. Ectopic beat: if QRS during tachycardia is similar to the one of PVB during Sinus R

4. Configuration of QRS in lead V1 or V6


Differential diagnosis of wide QRS tachycardia

1. Clinical circumstances(simple bedside clues to ventricular tachycardia)

– Advanced heart disease – Cannon 'a' waves in the JVP – Variable intensity of the S1 heart sound at the

apex (mitral closure)


Differential diagnosis of wide QRS tachycardia

2. Independent atrial activity(strongly suggests VT)

• direct sign - normal P wave–AV Dissociation

• indirect signs: capture beat and fusion beat


Differential Diagnosis of Wide QRS Tachycardias

( the followings are in favour of VT):• Bizarre QRS axis (i.e. from +150 degrees to -90

degrees ) suggests VT• Especially wide QRS complexes (>0.16s) • Positive or negative Concordance (If all the QRS

complexes from V1 to V6 are in the same direction)

4. Configuration of QRS in lead V1 or V6


Example of VT with positive concordance


Example of VT with negative concordance


Facts favouring VT• 80- 90 % of wide QRS complex tachycardia is VT• Aberrant conduction ( functional or rate related) is

rare especially if tachycardia persists• Presence of Capture or fusion beats• Previous ECG helps for preexisting BBB or PVB• For safety each wide QRS complex tachycardia is

VT until proved otherwise


Tachyarhythmias

Narrow complex Wide complex

Regular Irregular Regular Irregular

•ST

•AT

•SVT

•AFL

•AF

•MAT

•AFL /AT with

variable AV

conduction

•VT

•SVT

With aberrantconduction

AF with

accessory

pathway


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