EKG Module

ECG ModuleECG Module

The patient is an elderly man who presented to the emergency ward with dizziness

Rate – 42 bpm

Normal Sinus Rhythm

L axis deviationPR prolongation

Widened QRS

Peaked T waves

#16

Hyperkalemia (K 7.6) secondary to Hyperkalemia (K 7.6) secondary to acute renal failureacute renal failure

The earliest change (usu K>5.7) is a tall, peaked, most The earliest change (usu K>5.7) is a tall, peaked, most often often symmetrical (tented) T wave with a narrow basesymmetrical (tented) T wave with a narrow base Best seen in II,III, V2-4Best seen in II,III, V2-4 QRS complex may resemble RBBB, LBBB, LAFB, LPFBQRS complex may resemble RBBB, LBBB, LAFB, LPFB

Normal or decreased QTCNormal or decreased QTC QRS complex widens uniformly a level of 9 to 11 mEq/LQRS complex widens uniformly a level of 9 to 11 mEq/L Reduction in P-wave amplitude and PR prolongation Reduction in P-wave amplitude and PR prolongation

occurs K>7occurs K>7 At K>9 the P-wave becomes unrecognizableAt K>9 the P-wave becomes unrecognizable

SA and AV block as well as jxnal and escape rhythms can SA and AV block as well as jxnal and escape rhythms can also be seen.also be seen.

This 10-second rhythm shows at least three different rhythms! Can you find them?

Atrial Flutter Sinus BeatAtrial Fibrillation

Atrial FlutterAtrial Flutter Atrial rate is usu 250 to 350 bpm, but can be reduced to Atrial rate is usu 250 to 350 bpm, but can be reduced to

200 bpm with antiarrhythmic drugs200 bpm with antiarrhythmic drugs Ventricular Rate – usually half the atrial rateVentricular Rate – usually half the atrial rate

Significantly slower ventricular rate suggest AV nodal Significantly slower ventricular rate suggest AV nodal blockade or diseaseblockade or disease

ECG reveals regular sawtooth flutter waves best ECG reveals regular sawtooth flutter waves best visualized in II,III, AVf, or V1visualized in II,III, AVf, or V1 Inverted flutter waves in II and III are found in typical, type 1 Inverted flutter waves in II and III are found in typical, type 1

flutter due to counterclockwise re-entrant pathwayflutter due to counterclockwise re-entrant pathway Usually a regular rhythm except if there is variable blockUsually a regular rhythm except if there is variable block Flutter tends to be unstable and usually will revert to Flutter tends to be unstable and usually will revert to

sinus rhythm or degenerating into atrial fibrillationsinus rhythm or degenerating into atrial fibrillation

Atrial FibrillationAtrial Fibrillation Arrhythmia is characterized by wavelets propogating in Arrhythmia is characterized by wavelets propogating in

different directions different directions This caused disorganized atrial depolarization without effective This caused disorganized atrial depolarization without effective

atrial contractionatrial contraction On ECG, there are small irregular undulations of variable On ECG, there are small irregular undulations of variable

amplitudes called f wavesamplitudes called f waves Range from rates btw 350 and 600 bpm and commonly Range from rates btw 350 and 600 bpm and commonly

undetectable on surface ecgundetectable on surface ecg Represent multiple wavelets of depolarization generating larger Represent multiple wavelets of depolarization generating larger

vectorsvectors Ventricular response is grossly irregular and usu btw 100 Ventricular response is grossly irregular and usu btw 100

and 160 bpmand 160 bpm When ventricular rate is very rapid the rate may appear to be When ventricular rate is very rapid the rate may appear to be

more regularmore regular

Regular, Rate 93 bpm

Normal Sinus

Rhythm

R atrial enlargement

# 2

Regular Ventricular Rate 90 bpm

Atrial Rate 180 bpm

Ventricular Rate 180 bpm

85-year-old patient with valvular heart disease and congestive heart failure. #18

Regular, Rate 88 bpm

P-wave downward in II,

Not Sinus Rhythm

Atrial rate – 220 with 2:1 AV block

Atrial TachycardiaAtrial Tachycardia AT is a regular, atrial rate >100 bpm originating outside the sinus AT is a regular, atrial rate >100 bpm originating outside the sinus

nodenode Arise from a single site in contrast to Arise from a single site in contrast to A. fib or flutter which involve multiple A. fib or flutter which involve multiple sites or circuitssites or circuits

Arise fromArise from Increased automaticity – Increased automaticity – acceleration of a nl automatic pacemakeracceleration of a nl automatic pacemaker Triggered activity – focal electrical events that are called Triggered activity – focal electrical events that are called

afterdepolarizationsafterdepolarizations Microreentry – in which slow conduction allows for allowing to regain it Microreentry – in which slow conduction allows for allowing to regain it

ability to become excitability forming a reentrant circuitability to become excitability forming a reentrant circuit Atrial rate usu bte 130 – 250 Atrial rate usu bte 130 – 250

P wave morphology can be similar or different to sinus P-wave P wave morphology can be similar or different to sinus P-wave depending on the origin of the pacemakerdepending on the origin of the pacemaker

Usu AV conduction is 1:1, but 2:1 block can occur if atrial rate>200 Usu AV conduction is 1:1, but 2:1 block can occur if atrial rate>200 and/or with significant AV nodal diseaseand/or with significant AV nodal disease

51-year-old female with palpitations. # 5

Regular Rate 142 bpm

No clear P waves before QRS – Not sinus rhythm

Retrograde P-waves, with short RP interval

Resting ECG in a 65 year-old male with complaint of palpitations.



Retrograde P-waves, with short RP interval

Mechanism of ReentryMechanism of Reentry

An impulse initiated in the SA node passes through both the AV node and the accessory pathway

A premature atrial impulse occurs and reaches the accessory pathway when it is refractory, but conduction occurs through the AV node

The impulse takes sufficient time to circulate through the AV node to allow the accessory pathway to recover initiating reentry

Mechanisms of Supraventricular Tachycardia

AVNRT – the AV node is divided into two pathways and the activation of the atria and ventricle is synchronous so the retrograde P-wave is buried. Account for 60% of SVT. Usu are 150-200 bpm

Orthodromic AVRT – mechanism seen on previous slide. Usually, L atrium is the first site retrograde atrial activation. Accounts for 30% of SVT

Widened QRS

Antidromic AVRT – activation occurs in the opposite direction resulting in wide complex tachycardia that is indistinguishable from V tach



Wide QRS 160 ms

RBBB pattern

DDx of regular wide complex

tachycardia (WCT)

1) V. Tach

2) SVT w/ aberrant conduction or preexisting block

- Sinus tachycardia - A. flutter - AVRT/AVNRT - A. tachycardia

Retrograde P-waves associated

with the QRS complex

PVC

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A question of aberrancyA question of aberrancy Occurs when a supraventricular Occurs when a supraventricular

impulse encounters persistant impulse encounters persistant refractoriness in part of the refractoriness in part of the ventricular conduction system ventricular conduction system Refractory periodRefractory period RR intervalRR interval

Aberration can result from a Aberration can result from a shortened RR interval and shortened RR interval and refractory period (1) or a lengthened refractory period (1) or a lengthened RR interval and refractory period (2)RR interval and refractory period (2)

Always initially assume wide QRS is Always initially assume wide QRS is ventricular ventricular 80% of WCT are VT80% of WCT are VT

Triphasic rsR’ in V1 and qR in V6 Triphasic rsR’ in V1 and qR in V6 favor aberrancyfavor aberrancy

If the QRS morphology is similar If the QRS morphology is similar to sinus rhythm, then WCT to sinus rhythm, then WCT unlikely ventricular in originunlikely ventricular in origin

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Regular, Ventricular Rate 150 bpm

Wide QRS complex 180 ms

1) V. Tach

2) SVT w/ aberrant conduction or preexisting block

- Sinus tachycardia - A. flutter - AVRT/AVNRT - A. tachycardia

DDx of regular wide complex

tachycardia (WCT)

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Ventricular TachycardiaVentricular Tachycardia VT consists of at least three consecutive QRS complexes VT consists of at least three consecutive QRS complexes

originating from the ventricles and recurring at a rapid rate (>120 originating from the ventricles and recurring at a rapid rate (>120 bpm)bpm)

As a consequence of ischemic heart diseaseAs a consequence of ischemic heart disease May appear almost immediately after prox obstruction of a major May appear almost immediately after prox obstruction of a major

coronary artery – tends to be unstable VT that can degenerate into Vfibcoronary artery – tends to be unstable VT that can degenerate into Vfib Weeks to months after an MI – more stable VT can occurWeeks to months after an MI – more stable VT can occur

Other – nonischemic cardiomyopathy (idiopathic dilated, HOCM), Other – nonischemic cardiomyopathy (idiopathic dilated, HOCM), RV outflow tract, medicationsRV outflow tract, medications

Distinguishing btw VT and SVT with aberrant conductionDistinguishing btw VT and SVT with aberrant conduction AV dissociationAV dissociation Fusion and Capture beatsFusion and Capture beats No RS pattern in any of the precordial leads suggests VTNo RS pattern in any of the precordial leads suggests VT BiphasicBiphasic Rsr or monophasic R waves are suggestive of VT Rsr or monophasic R waves are suggestive of VT

Sustained VT is defined if it lasts for >30 seconds or more than 10 Sustained VT is defined if it lasts for >30 seconds or more than 10 beatsbeats

RBBB

Missed Beat – not sinus rhythm

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AV blockAV block Delay or interruption in the transmission of an impulse Delay or interruption in the transmission of an impulse

from the atria to the ventricles due to an anatomical or from the atria to the ventricles due to an anatomical or functional impairment in the conduction system. functional impairment in the conduction system.

EtiologyEtiology Idiopathic progressive cardiac conduction disease (rare)Idiopathic progressive cardiac conduction disease (rare) Ischemic heart disease (approx 40%)Ischemic heart disease (approx 40%) DrugsDrugs Increased vagal toneIncreased vagal tone Valvular disease – calcification of aortic and mitral valveValvular disease – calcification of aortic and mitral valve Infection – Lyme disease, toxoplasmosis, endocarditis, syphilis Infection – Lyme disease, toxoplasmosis, endocarditis, syphilis

diphthiria, rheumatic feverdiphthiria, rheumatic fever Infitrative process – sarcoidosis, amyloidInfitrative process – sarcoidosis, amyloid Inflammatory – SLE, rheumatoidInflammatory – SLE, rheumatoid HyperkalemiaHyperkalemia

Wenckebach: Mobitz type 1Wenckebach: Mobitz type 1 Almost always involves the AV nodeAlmost always involves the AV node Marked by gradual lengthening of the PR interval and a Marked by gradual lengthening of the PR interval and a

gradual shortening of the RR interval and an eventual dropped gradual shortening of the RR interval and an eventual dropped beatbeat The first PR interval of the second cycle will invariably be The first PR interval of the second cycle will invariably be

shorter than the last PR interval of the preceding cycleshorter than the last PR interval of the preceding cycle Progressive PR interval occurs because each atrial impulse Progressive PR interval occurs because each atrial impulse

arrives progressively earlier in the refractory period of the AV arrives progressively earlier in the refractory period of the AV nodenode This it takes progressively longer to penetrate the node and This it takes progressively longer to penetrate the node and

reach the ventriclesreach the ventricles Maximal increase in the PR interval happens btw the first and Maximal increase in the PR interval happens btw the first and

second cycle, and the increase becomes successively smaller second cycle, and the increase becomes successively smaller in subsequent cyclesin subsequent cycles This leads to progressively shortening of the RR intervalThis leads to progressively shortening of the RR interval

LBBB

Non conducting beat

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Atrial rate 88 bpm

Ventricular rate 50 bpm

Complete Heart BlockComplete Heart Block Always produces AV disassociationAlways produces AV disassociation

Independent atrial and ventricular rateIndependent atrial and ventricular rate But AV disassociation can be caused byBut AV disassociation can be caused by

Decreased sinus automaticty, junctional or ventricular Decreased sinus automaticty, junctional or ventricular escape, ventricular tachycardia which make the AV node escape, ventricular tachycardia which make the AV node refractory so the sinus impulse cannot traverse the AV noderefractory so the sinus impulse cannot traverse the AV node

If the sinus rate < ventricular rate then one must If the sinus rate < ventricular rate then one must consider that a junctional or ventricular consider that a junctional or ventricular pacemaker has taken over pacemaker has taken over

If the sinus rate > ventricular rate, then If the sinus rate > ventricular rate, then complete heart block becomes apparent, as both complete heart block becomes apparent, as both the atrial and ventricular complexes maintain the atrial and ventricular complexes maintain independent rhythmsindependent rhythms

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EKG Module