Electrocardiography & Cardiac Arrhythmias

Electrocardiography & Cardiac Arrhythmias
Saeed Oraii MD, Cardiologist Interventional Electrophysiologist Tehran Arrhythmia Clinic

Some slides have accompanied notes
Some slides have accompanied notes. To view them you can right click on the screen, choose ‘Screen’ and then ‘Speaker Notes’. Tehran Arrhythmia Center

ECG A graphic recording of electrical potentials generated by the heart A noninvasive, inexpensive and highly versatile test Tehran Arrhythmia Center

Normal Pathway of Electrical Conduction
Atria and ventricles can be considered as two distinct syncitia as the cells are closely connected to each other. The two syncitia are separated by an insulated barrier that consists of the valves and central fibrous trigone. No impulse can normally pass this barrier except through the “penetrating” bundle of His. Left bundle branch is divided into left anterior and left posterior fascicles and possibly a septal fascicle. Tehran Arrhythmia Center

Cardiac Action Potential
Tehran Arrhythmia Center

Cardiac action potentials from different locations have different shapes
Sinus node and AV nodal cells depolarize mainly through activation of slow Ca channels. So the upstroke of the phase 0 of action potential is less steep. Tehran Arrhythmia Center

Electrophysiology Electric currents that spread through the heart are produced by three components Cardiac pacemaker cells Specialized conduction tissue The heart muscle ECG only records the depolarization and repolarization potentials generated by atrial and ventricular myocardium. Tehran Arrhythmia Center

Electrocardiograph 1903 Tehran Arrhythmia Center

Normal Electrocardiogram

Labeled alphabetically beginning with the P wave
ECG Waveforms Labeled alphabetically beginning with the P wave Tehran Arrhythmia Center

QRS-T Cycle Corresponds to Different Phases of Ventricular Action Potential
QRS wave corresponds to ventricular depolarization and T wave to ventricular repolarization. Tehran Arrhythmia Center

Limb Leads Tehran Arrhythmia Center
I, II and III are bipolar limb leads. VR, VL and VF are unipolar leads. The positive pole of these leads are connected to the corresponding limb and zero pole is created by connecting all the three angles of the “Einthoven” triangle to negative pole. Unipolar leads aVR, aVL and aVF are simply augmented leads by excluding the corresponding lead from zero pole. Tehran Arrhythmia Center

Precordial Leads Tehran Arrhythmia Center
Limb leads record electrical signals spread in frontal plane. Precordial leads are created to record signals in transverse plane too. Tehran Arrhythmia Center

Position of Precordial Electrodes
Precordial leads are unipolar leads. Tehran Arrhythmia Center

Precordial Leads Tehran Arrhythmia Center
One may record the signals from the right side of the chest by positioning the electrodes as mirror images of the left sided electrodes. An “R” is added to the end of the name of the lead to show that they are recorded from the right side. Tehran Arrhythmia Center

3-D Representation of Cardiac Electrical Activity
Limb leads record electrical signals spread in frontal plane. Precordial leads record signals in transverse plane. Tehran Arrhythmia Center

Timing Intervals Tehran Arrhythmia Center

Vector Concept Cardiac depolarization and repolarization waves have direction and magnitude. They can, therefore, be represented by vectors. ECG records the complex spatial and temporal summation of electrical potentials from multiple myocardial fibers conducted to the surface of the body. Tehran Arrhythmia Center

Limb Leads Directions Tehran Arrhythmia Center

Vector Concept Tehran Arrhythmia Center
Each lead has a vector. If the signal is parallel to the vector of that lead, it will record the largest positive signal. If it goes right in the opposite direction, a large negative deflection is recorded. And if the electrical signal goes perpendicular to the vector of the lead it will not record anything i.e. an isoelectric or equiphasic line is depicted. Tehran Arrhythmia Center

Ventricular Depolarization
The first part of the ventricles to be depolarized is the left side of interventricular septum. The electrical current goes from the left toward the right side. Therefore a small positive deflection is depicted by right precordial leads (V1 and V2) and a small initial q wave called “septal q wave” is depicted by left precordial leads (V5 and V6). Tehran Arrhythmia Center

QRS Axis Tehran Arrhythmia Center

Determination of QRS Axis

Direction of Propagation

Determination of QRS Axis

Main Vector Tehran Arrhythmia Center
You may determine an axis for each part of the QRS (instantaneous vector) for example the initial 40 ms of the QRS. A main axis is determined by considering the whole QRS (main vector). Tehran Arrhythmia Center

Normal QRS Axis Tehran Arrhythmia Center

Left Axis Deviation Tehran Arrhythmia Center

Right Axis Deviation Tehran Arrhythmia Center

Major ECG Abnormalities

Right Atrial Enlargement
Tall P waves usually best recorded in inferior leads. Also called “P Pulmonale”. Tehran Arrhythmia Center

Left Atrial Enlargement
Broad biphasic P waves in inferior leads. Increase terminal negative portion of P wave in V1. Also called “P Mitrale”. Tehran Arrhythmia Center

Left Ventricular Hypertrophy

Right Ventricular Hypertrophy

RVH, RA enlargement Tehran Arrhythmia Center

Left Bundle Branch Block

Right Bundle Branch Block

RBBB Tehran Arrhythmia Center

RBBB, RAD (Bifascicular Block)

RBBB, LAD (Bifascicular Block)

Myocardial Ischemia ECG is the cornerstone in the diagnosis of myocardial ischemia Findings depend on several factors: Nature of the process, reversible vs. irreversible Duration, acute vs. chronic Extent, transmural vs. subendocardial Localization, anterior vs. inferoposterior Other underlying abnormalities Tehran Arrhythmia Center

Acute Ischemia Tehran Arrhythmia Center

Myocardial Infarction

Acute Pericarditis Tehran Arrhythmia Center

Metabolic Abnormalities

Hyper-kalemia K 6.9 Tehran Arrhythmia Center

Same patient K 3.9 Tehran Arrhythmia Center

Hypothermia, Osborn Wave

Hypothermia, Corrected

Right Axis Deviation Tehran Arrhythmia Center Tehran Arrhythmia Center

Superior P Wave Axis Tehran Arrhythmia Center Tehran Arrhythmia Center

Normal Sinus Rhythm Tehran Arrhythmia Center Tehran Arrhythmia Center

Anterior MI Tehran Arrhythmia Center Tehran Arrhythmia Center

RBBB and Inferior MI Tehran Arrhythmia Center Tehran Arrhythmia Center

LA Enlargement and Prolonged PR Interval
Tehran Arrhythmia Center Tehran Arrhythmia Center

LBBB Tehran Arrhythmia Center Tehran Arrhythmia Center

LA Enlargement and Prolonged PR Interval

Left Anterior Hemiblock

LVH and LA Enlargement Tehran Arrhythmia Center

Anterior MI Tehran Arrhythmia Center Tehran Arrhythmia Center

Old Inferior MI Tehran Arrhythmia Center Tehran Arrhythmia Center

RA Enlargement Tehran Arrhythmia Center Tehran Arrhythmia Center

RBBB, LAH, Prolonged PR (Trifascicular Block)

RBBB and Inferior MI Tehran Arrhythmia Center Tehran Arrhythmia Center

Tehran Arrhythmia Center

Cardiac Arrhythmias Tehran Arrhythmia Center

Normal Pathway of Electrical Conduction

Normal Sinus Rhythm Normal and constant P wave contours
Normal P wave axis Rate between 60 and 100 bpm Tehran Arrhythmia Center

Normal Sinus Rhythm Tehran Arrhythmia Center Tehran Arrhythmia Center

Anatomical Aspects of Normal Sinus Node
Located at the superior anterolateral portion of right atrium near its border with the superior vena cava It is an epicardial structure near sulcus terminalis From endocardial approach the closest approach is near the superior end of crista terminalis Tehran Arrhythmia Center

Sinus Node Function The dominant cardiac pacemaker
Highly responsive to autonomic influences Decreasing rate with vagal stimulation Increasing rate with sympathetic activity Normal sinus rate under basal conditions is bpm. Tehran Arrhythmia Center

Sinus Tachycardia Sinus rhythm exceeding 100 bpm in adults
Usually between 100 and 180 bpm but may be higher with extreme exertion Maximum heart arte decreases wit age from near 200 bpm to less than 140 bpm Gradual onset and termination Tehran Arrhythmia Center

Sinus Tachycardia Tehran Arrhythmia Center

Sinus Tachycardia Causes
Common in infancy and childhood Normal response to a variety of physiological and pathological stresses Exertion, anxiety Hypovolemia, anemia Fever Congestive heart failure Myocardial ischemia Thyrotoxicosis Drugs Inflammation Tehran Arrhythmia Center

Sinus Bradycardia Sinus rhythm at a rate less than 60 bpm
Can result from excessive vagal or decreased sympathetic tone as well as anatomic changes in sinus node Frequently occurs in healthy young adults, particularly well-trained athletes Sinus arrhythmia often coexists Tehran Arrhythmia Center

Sinus Bradycardia Tehran Arrhythmia Center
Because of severe sinus bradycardia, Junctional ‘escape’ beats have appeared. Tehran Arrhythmia Center

Sinus Bradycardia Causes
Hypothyroidism Drugs During vomiting or vasovagal syncope Increased intracranial pressure Hypoxia, hypothermia Infections Depression Jaundice Tehran Arrhythmia Center

Sinus Arrhythmia Phasic variation in sinus cycle length
Maximum minus minimum sinus cycle length exceeds 120 msec. May be considered the most common form of arrhythmia Respiratory form is a normal event Common in the young esp. with slower heart rates or enhanced vagal tone Tehran Arrhythmia Center

Sinus Arrhythmia Tehran Arrhythmia Center

Wandering Pacemaker Passive transfer of dominant pacemaker focus from sinus node to latent pacemakers in other atrial sites or AV junctional tissue Occurs in a gradual fashion over the duration of several beats Tehran Arrhythmia Center

Wandering Pacemaker ECG
A cyclical increase in RR interval A PR interval that gradually shortens to less than 120 msec A change in P wave contour that becomes negative in lead I or II or is lost within the QRS Tehran Arrhythmia Center

Wandering Pacemaker Tehran Arrhythmia Center

Inappropriate Sinus Tachycardia
Persistent sinus tachycardia at rest or with minimal exertion Usually occurs in otherwise healthy people More common in health care personnel May result from a defect in either sympathetic or vagal nerve control of sinus node automaticity or an abnormality of intrinsic heart rate Some cases may need radiofrequency ablation of sinus node Tehran Arrhythmia Center

Sinus Node Dysfunction Mechanisms
A disease affecting a limited amount of tissue at or near the sinus node causing dysfunction of impulse formation or propagation or recovery from overdrive suppression A disease affecting the atria in general that consequently affects the sinus node function and also frequently generates atrial arrhythmias Tehran Arrhythmia Center

Sinus Node Dysfunction ECG Manifestations
Sinus bradycardia Sinus pauses Sinus arrest Atrial asystole Sinus exit block Tehran Arrhythmia Center

Sinus Pause Tehran Arrhythmia Center

Sinoatrial Exit Block 1st and 2nd degree

Sinus Node Dysfunction Etiology
Most often in elderly as an isolated phenomenon Drugs Infiltration of atrial myocardium Interruption of blood supply Hypothyroidism, advanced liver disease, severe hypoxia, acidemia … Tehran Arrhythmia Center

High Vagal Tone Usually in the young
Normal heart rate response during exercise Normal intrinsic heart rate Bradycardia may be severe enough to cause syncope (especially in familial form) Tehran Arrhythmia Center

Sick Sinus Syndrome A combination of symptoms (dizziness, fatigue, confusion, syncope and congestive heart failure) caused by sinus node dysfunction Atrial tachyarrhythmias may accompany sinus node dysfunction <bradycardia-tachycardia syndrome> Tehran Arrhythmia Center

Sick Sinus Syndrome Clinical Manifestations
Predominantly seen in the elderly Most patients with sinus node dysfunction are asymptomatic Two types of presentations Syncope or near-syncope Fatigue or worsening heart failure Tehran Arrhythmia Center

Sick Sinus Syndrome Diagnosis
Holter monitor recordings Intrinsic heart rate by autonomic blockade Sinus node recovery time Sinoatrial conduction time The most important step is to correlate symptoms with ECG findings. Tehran Arrhythmia Center

Normal SNRT Tehran Arrhythmia Center

Abnormal SNRT Tehran Arrhythmia Center

SA Block during Overdrive Pacing

Sinus Arrest after Termination of AF

Loop Recorder Showed Junctional Rhythm during Syncope

Sinus arrest with syncope

Therapy for Sick Sinus Syndrome
Based mostly on symptoms and any clinical documentation of cardiac arrhythmia associated with these symptoms Drug therapy is rather limited Most effective treatment is pacing therapy Anticoagulation in certain situation Tehran Arrhythmia Center

Heart Block Disturbance of impulse conduction Transient or permanent
Due to anatomical or functional impairment Must be distinguished from interference, a normal phenomenon that is a disturbance of impulse conduction caused by physiological refractoriness due to inexcitability from a preceding impulse Tehran Arrhythmia Center

AV Conduction Disturbances Clinical Significance
Heart block may be asymptomatic or lead to syncope or cardiac arrest Clinical significance of conduction abnormalities depend on: The site of disturbance The risk of progression to complete block The probability that a subsidiary escape rhythm distal to the site of block develops and is stable Tehran Arrhythmia Center

AV Block Types First degree AV block Second degree AV block
Mobitz type I (Wenckebach) Mobitz type II Third degree block (Complete heart block) High degree (advanced) AV block Tehran Arrhythmia Center

First Degree AV Block Conduction time is prolonged but all impulses are conducted. PR interval exceeds 0.2 sec in adults Site of conduction delay may be in the AV node (most commonly), in the His-Purkinje system or both. Tehran Arrhythmia Center

First Degree AV Block Tehran Arrhythmia Center

Second Degree AV Block Block of some atrial impulses at a time when physiological interference is not involved Non-conducted P waves can be infrequent or frequent, at regular or irregular intervals, and can be preceded by fixed or lengthening PR intervals. The association of P with QRS is not random. Tehran Arrhythmia Center

Mobitz Type I Second Degree AV Block
Also called Wenckebach block Typical type characterized by progressive PR prolongation culminating in a non-conducted P wave Narrow QRS in most cases Tehran Arrhythmia Center

WB Tehran Arrhythmia Center

Wenckebach Block Tehran Arrhythmia Center

Wenckebach Block Atypical pattern in over half the cases
The site of block is almost always in the AV node. Generally benign and does not advance to more advanced AV block Can occur in normal children and well-trained athletes Tehran Arrhythmia Center

Mobitz Type II Second Degree AV Block
PR interval remains constant prior to the blocked P wave Commonly associated with bundle branch blocks Tehran Arrhythmia Center

Site of block His-Purkinje system in most case Often antedates the development of Adams-Stokes syncope and complete AV block Never observed in normal people An indication for implantation of permanent pacemaker even in asymptomatic cases Tehran Arrhythmia Center

2:1 AV Block Tehran Arrhythmia Center

2:1 AV block Tehran Arrhythmia Center

Complete AV block No atrial activity conducts to the ventricles
AV dissociation is present. The atria and ventricles are controlled by independent pacemakers. Ventricular focus is usually located just below the site of block. Higher sites are more stable with a more faster escape rate. Tehran Arrhythmia Center

Complete AV block Tehran Arrhythmia Center
P waves and R waves are completely dissociated. No P waves are conducted. Tehran Arrhythmia Center

Complete AV block Isorhythmic AV Dissociation
It may look that one of every 3 P waves are conducted to ventricle. However at closer look you can see that the interval between each QRS and its preceding P is changing i.e. the P wave are “marching” over QRS waves (AV dissociation). Tehran Arrhythmia Center

Advanced AV block Block in two or more consecutive P waves

AV Conduction Disturbances Etiology
Degenerative diseases are the most common causes A variety of other diseases may be responsible: myocardial infarction, drugs, acute infections, infiltrative diseases, neoplasms, etc. Hypervagotonia Tehran Arrhythmia Center

Investigation of the Site of AV Conduction Disease by Electrophysiologic Study (EPS)

Cardiac Pacemakers The treatment of symptomatic bradyarrhythmias is implantation of cardiac pacemakers. Tehran Arrhythmia Center

Cardiac Pacing Tehran Arrhythmia Center

First Implanted Pacemaker

Common Uses for Permanent Pacemaker Therapy

AV Block With Carotid Massage

Long Asystole Tehran Arrhythmia Center

Sinus Pause and Junctional Escape Beats

Bradycardia- Tachycardia Syndrome

Mobitz Type I (Wenckebach)

2:1 AV block Tehran Arrhythmia Center Tehran Arrhythmia Center

Complete Heart Block Tehran Arrhythmia Center Tehran Arrhythmia Center

Sinus Pause Tehran Arrhythmia Center Tehran Arrhythmia Center

Sinus Arrhythmia Tehran Arrhythmia Center Tehran Arrhythmia Center

Sinus Tachycardia Tehran Arrhythmia Center Tehran Arrhythmia Center

Wandering Pacemaker Tehran Arrhythmia Center Tehran Arrhythmia Center

Sinus Tachycardia Tehran Arrhythmia Center Tehran Arrhythmia Center

Wandering Pacemaker Tehran Arrhythmia Center Tehran Arrhythmia Center

Asystole and Junctional Escape Rhythm

Tachyarrhythmias Tehran Arrhythmia Center

Tachyarrhythmias Mechanisms
Automaticity Tehran Arrhythmia Center

Triggered activity Tehran Arrhythmia Center

Reentry Tehran Arrhythmia Center

Premature Complexes Tehran Arrhythmia Center

Ventricular Premature Complexes
Compensatory Pause Interpolated VPC Tehran Arrhythmia Center

Premature Complexes The most common arrhythmias
Detected during 24h Holter monitoring in over 60% of adults May cause palpitations or be asymptomatic May trigger more serious tachyarrhythmias May be associated with a normal heart or a variety of cardiac disturbances Tehran Arrhythmia Center

Variability of Ventricular Ectopy with Age
Effect of age on probability (%) of having more than a given number of PVCs per 24 hours in subjects with normal hearts. 10-29 30-39 40-49 50-59 60-69 Age Data from Kostis JB. Circulation ;63(6):1353. Tehran Arrhythmia Center

Ventricular Premature Complexes
Without heart disease, PVCs have not been shown to be associated with any increased incidence in morbidity or mortality In the presence of underlying disease (ischemia, heart failure …) they may add to the risk of the disease. No treatment is, however, shown to definitely decrease this increased risk. Tehran Arrhythmia Center

Atrial Fibrillation The most common sustained arrhythmia
Incidence increases progressively with age. Prevalence: 0.4% of overall population Mortality rate double that of control AF is characterized by disorganized atrial activity without discrete P waves Tehran Arrhythmia Center

Atrial Fibrillation Tehran Arrhythmia Center

Atrial Fibrillation Undulating baseline or atrial deflections of varying amplitude and frequency ranging from 350 to 600 bpm. Irregularly irregular ventricular response. Tehran Arrhythmia Center

Atrial Fibrillation Morbidity related to: Excessive ventricular rate
Pause following cessation of AF Systemic embolization Loss of atrial kick Anxiety secondary to palpitations Irregular ventricular rate Tehran Arrhythmia Center

Atrial Fibrillation Persistent AF usually in patients with cardiovascular disease Valvular heart disease Hypertensive heart disease Congenital heart disease Paroxysmal AF may occur with acute hypoxia, hypercapnia or metabolic or hemodynamic derangements Normal people with emotional stress or surgery or acute alcoholic intoxication Lone AF Tehran Arrhythmia Center

Atrial Fibrillation Therapeutic Goals: Control of ventricular rate
Restoration and maintenance of sinus rhythm Prevention of thromboembolism Tehran Arrhythmia Center

Atrial Flutter Regular atrial tachyarrhythmia with atrial rate between bpm. Flutter waves are seen as saw-tooth like atrial activity Tehran Arrhythmia Center

Atrial Flutter Atrial Flutter is a form of atrial reentry localized to right atrium. Typically the ventricular rate is half the atrial rate, but the ventricular response may be 4:1, 2:1, 1:1 etc. Tehran Arrhythmia Center

Atrial Flutter Circuit

Atrial Flutter Tehran Arrhythmia Center Tehran Arrhythmia Center

Atrial Flutter Most often in patients with organic heart disease
Usually less long-lived than AF and may convert to AF. Control of ventricular rate is difficult in atrial flutter The most effective treatment is DC cardioversion Tehran Arrhythmia Center

Paroxysmal Supraventricular Tachycardia (PSVT)
Usually at a rate of bpm No organic heart disease in the majority Presentations Palpitations Chest discomfort,dyspnea, lightheadedness Frank syncope SCD Tehran Arrhythmia Center

PSVT Tehran Arrhythmia Center Tehran Arrhythmia Center
Paroxysmal Supraventricular Tachycardia (PSVT) is a general term applied for recurrent paroxysmal tachycardias with different mechanisms but arising above ventricles. They usually have a narrow QRS complex and the rate is between bpm. P waves may or may not be seen during the tachycardia. Tehran Arrhythmia Center Tehran Arrhythmia Center

PSVT Mechanism Reentry in the vast majority
Reentry may be localized to sinus node, atrium, AV junction or a macroreentrant circuit involving a bypass tract (WPW) In the absence of WPW, more than 90% are due to reentry through AV node or a concealed bypass tract Tehran Arrhythmia Center

AV Nodal Reentrant Tachycardia (AVNRT)
The most common form of paroxysmal supraventricular tachycardia (about 70%) More common in women (66%) Usually a regular narrow QRS complex tachycardia No P wave is usually evident during the tachycardia. Retrograde P waves may occasionally be seen at the end of QRS. Tehran Arrhythmia Center

Longitudinal Dissociation Within AV Node
Slow Pathway Fast Pathway Atrium His Bundle Tehran Arrhythmia Center

AVNRT Tehran Arrhythmia Center

Preexcitation Tehran Arrhythmia Center
There is an abnormal electrical leak in the insulation between atria and ventricles. This is called an “accessory pathway” or “bypass tract”. Before the impulse is conducted through the normal AV conduction system the ventricles are excited prematurely through this tract, so the term “pre-excitation”. The result is shortened PR segment and the presence of “delta wave”. Tehran Arrhythmia Center

Wolff-Parkinson-White Syndrome
If the patient with preexcitation develops symptoms (PSVT, Atrial fibrillation…) it will be called Wolff-Parkinson-White syndrome of “WPW”. Tehran Arrhythmia Center Tehran Arrhythmia Center

AV Reentrant Tachycardia (AVRT)
Incorporates a bypass tract as part of the tachycardia circuit. Surface ECG: Manifest with short PR interval and delta wave (preexcitation) Concealed with normal ECG Prevalence of ECG pattern: 0.1% to 0.3%. Tehran Arrhythmia Center

AVRT Tehran Arrhythmia Center

Concealed Accessory Pathway
Sometimes there is an accessory pathway but it can only conduct impulses retrogradely (from ventricle to atrium) but it cannot conduct the impulse antegradely (from atrium to ventricle). Therefore ECG during sinus rhythm will be normal but the patient can still have reentrant tachycardia (AVRT). These pathways are called “concealed” accessory pathways. Tehran Arrhythmia Center Tehran Arrhythmia Center

PSVT Treatment Vagal maneuvers particularly carotid sinus massage
AV nodal blocking drugs Adenosine Verapamil Propranolol Digoxin DC cardioversion if hypotensive Radiofrequency ablation Tehran Arrhythmia Center

Electrophysiologic Study (EPS)
EPS is conducted to record and study the conduction system and electrical currents directly. Catheters are inserted through femoral veins and positioned at different points inside the heart. Signals collected through the electrodes of these catheters are shown and analyzed through a sophisticated EP machine. Tehran Arrhythmia Center

Catheter Positions at Fluoroscopy

Intracardiac Recordings
Signals are recorded through the electrodes over the catheters positioned inside heart. Tehran Arrhythmia Center

Radiofrequency Ablation (RFA)
Through femoral vein and right atrium After identifying the faulty focus, e.g. a bypass tract, a special catheter is positioned right over the desired position and the abnormal focus is burned (ablated) by the emission of radiofrequency energy from the tip of the catheter. Tehran Arrhythmia Center

Loss of Delta during RF Burn

Loss of Delta during Burn

Ventricular Arrhythmias Definitions
Premature Ventricular beats Single beats Ventricular Bigeminy, the appearance of one PVC after each sinus beat Couplets, two consecutive premature beats Triplets, three consecutive premature beats Salvos, runs of 3-10 premature beats Accelerated Idioventricular Rhythm (Slow VT), rate bpm Ventricular Tachycardia (VT), rate over 100 bpm Ventricular Flutter, regular large oscillations at a rate of bpm Ventricular Fibrillation (VF), irregular undulations of varying contour and amplitude Tehran Arrhythmia Center

Ventricular Tachycardia Classification
Duration Sustained VT defined as VT that persists for than 30 s or requires termination because of hemodynamic collapse Nonsustained VT, 3 beats to 30 s Morphology Monomorphic Polymorphic QRS complexes in monomorphic VT have the same morphology in a single lead. In polymorphic VT, QRS morphology in a single lead is variable and changing. Tehran Arrhythmia Center

Salvos Tehran Arrhythmia Center

Sustained Monomorphic VT

Sustained Polymorphic VT

VT, Holter Recording Tehran Arrhythmia Center
This is called “repetitive monomorphic VT”. Tehran Arrhythmia Center

VT Presentations Tehran Arrhythmia Center

VT Etiology VT generally accompanies some form of structural heart disease most commonly: Ischemic heart disease Cardiomyopathies Primary electrical abnormalities Long QT syndromes Brugada syndrome Idiopathic VT Tehran Arrhythmia Center

Electrocardiographic Differentiation of VT vs. SVT with Aberrancy
Clinical history AV dissociation QRS morphology QRS axis Fusion beat Capture beat QRS is usually narrow with supraventricular tachycardias (SVT) and wide with ventricular tachycardias (VT). However, some supraventricular tachycardias have wide QRS complexes. This is usually due to a faulty conduction of impulses to ventricles, so “SVT with aberrancy”. Tehran Arrhythmia Center

A-V Dissociation, Fusion, and Capture Beats in VT
ECTOPY FUSION CAPTURE Fisch C. Electrocardiography of Arrhythmias ;134. Tehran Arrhythmia Center

Fusion and Capture Beats in VT
Fisch C. Electrocardiography of Arrhythmias ;135. Tehran Arrhythmia Center

VT Prognosis Depends on the underlying disease state
75% first year mortality in the first few weeks after MI Poor prognosis in patients with left ventricular dysfunction No increased risk in those with idiopathic VT Tehran Arrhythmia Center

Ventricular Fibrillation

Sudden Death Syndrome Incidence High recurrence rate
400, ,000/year in U.S. Only 2% - 15% reach the hospital Half of these die before discharge High recurrence rate Tehran Arrhythmia Center

Underlying Arrhythmia of Sudden Death
Primary VF 8% Torsades de Pointes 13% VT 62% Bradycardia 17% Adapted from Bayés de Luna A. Am Heart J ;117: Tehran Arrhythmia Center

Snapshot of Death Tehran Arrhythmia Center Tehran Arrhythmia Center
This is a Holter recording from a patient who has experienced ventricular tachycardia followed by ventricular fibrillation during sleep. Tehran Arrhythmia Center

Return of Life Not the usual case !
Tehran Arrhythmia Center Return of Life Not the usual case ! Quite interestingly VF stopped spontaneously and a long cardiac standstill followed. However after a while escape beats started to appear and he returned to life! Tehran Arrhythmia Center

Clinical Substrates Associated with VF Arrest
Coronary artery disease Idiopathic cardiomyopathy Hypertrophic cardiomyopathy Long QT syndrome RV dysplasia Rarely: WPW syndrome Tehran Arrhythmia Center

VT/VF Therapeutic Options
Antiarrhythmic drugs Anti-tachycardia pacing Radiofrequency ablation Implantable defibrillators Tehran Arrhythmia Center

Earliest Defibrillator in Clinical Use, 1899

First Implantable Defibrillator 1970

Thoracotomy Lead System, the technique used at the beginning

Nonthoracotomy Lead System

Pectoral Implantation The Current Technique

Tiered Therapy Defibrillators

Defibrillator Function

Interrogated ICD Event
VT, treated appropriately by burst pacing therapy Tehran Arrhythmia Center

VT (CL 320ms), no response to burst pacing therapy Tehran Arrhythmia Center

VT (CL 320ms), cardioverted by DC shock Tehran Arrhythmia Center

Clinical Uses of Defibrillator Therapy

Congenital Long QT Syndrome
A Frequently Missed Diagnosis

Long QT Interval Tehran Arrhythmia Center

Clinical Manifestations
Long QT syndrome is characterized by the presence of a long QT interval (usually over 440 ms) and emergence of ventricular arrhythmias. The presenting arrhythmia is a polymorphic ventricular tachycardia called ‘Torsade de Pointes’. Patient present with recurrent syncope or sudden cardiac death. Early diagnosis by ‘looking at ECG’ is critical! Tehran Arrhythmia Center

Torsade de Pointes Prolonged QT interval associated with a polymorphic VT characterized by QRS complexes that change in amplitude and cycle length, giving the appearance of oscillations around the baseline Congenital or acquired Tehran Arrhythmia Center

Brugada Syndrome Definition
Clinical-electrocardiographic diagnosis based on: High incidence of sudden cardiac death Structurally normal heart Characteristic ECG pattern Tehran Arrhythmia Center

ECG Abnormalities ST segment elevation in V1-V3
QRS complex resembling RBBB J-point elevation Tehran Arrhythmia Center

Brugada ECG Pattern Tehran Arrhythmia Center

History First time in 1986: a 3-year polish boy
First presentation at NASPE meeting in 1991 First paper by Pedro and Josep Brugada in 1992 In the Philippines as “ bangungut” In Japan as “Pokkuri” In Thailand as “ Lai tai”, SUDS Circ. 1997 Thai men correlated to Brugada, SUNDS Hum. Mol. Gen. 2002 Tehran Arrhythmia Center

Brugada Syndrome Prevalence in men (8:1 ratio males: females)
Familial incidence (autosomal dominant with incomplete penetrance ranging between 5 and 66 per ) True prevalence is difficult to estimate as the ECG pattern is often concealed. It is endemic in Southeast Asia including: Thailand, Japan, Laos, Cambodia, Vietnam, the Philippines, and China. Appearance of arrhythmic events at an average age of 40 years Tehran Arrhythmia Center

Clinical Manifestations
Sudden cardiac death Syncope, seizure, agonal respiration, Episodes at night during sleep with labored respiration, agitation, loss of urinary control, recent memory loss Most commonly occurs during sleep, in particular during the early morning hours Early diagnosis is of utmost importance The only treatment is currently implantation of an ‘Implantable Cardioverter Defibrillator’. Tehran Arrhythmia Center

Electrocardiography & Cardiac Arrhythmias

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