ECG, Conduction disturbances

Conduction DisturbancesConduction Disturbances

Dr Majid Shojaee Dr Majid Shojaee Assistant professor of emergency medicineAssistant professor of emergency medicineShahid beheshti medical university Shahid beheshti medical university

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Only single shape POnly single shape P33

Sinus bradycardiaSinus bradycardiasinus tachycardia…sinus tachycardia…sinus dysrhythmia (arhythmia)sinus dysrhythmia (arhythmia)sinus pause (arrest)sinus pause (arrest)sinoatrial blocksinoatrial block

SINUS DYSRHYTHMIASINUS DYSRHYTHMIA Some variation in the sinus node Some variation in the sinus node

discharge rate is common, but discharge rate is common, but if the if the variation exceeds 0.12 svariation exceeds 0.12 s between between the longest and shortest intervals, the longest and shortest intervals, sinus dysrhythmia sinus dysrhythmia is present.is present.

The The ECG:ECG: (1) normal sinus P waves and P-R (1) normal sinus P waves and P-R

intervals, (2) 1:1 AV conduction, andintervals, (2) 1:1 AV conduction, and (3) variation of at least 0.12 s between (3) variation of at least 0.12 s between

the shortest and longest P-P intervalthe shortest and longest P-P interval44

Sinus ArrhythmiaSinus Arrhythmia

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Sinus dysrhythmia:(note slight irregularity).Sinus dysrhythmia:(note slight irregularity).

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Sinus Arrest (Pause)Sinus Arrest (Pause) Sinus pause is a failure of impulse Sinus pause is a failure of impulse

formation within the sinus node. formation within the sinus node. In sinus arrest, the P-P interval has In sinus arrest, the P-P interval has

nono mathematical relation to the mathematical relation to the basic sinus node discharge ratebasic sinus node discharge rate

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The pause is not equal to exactly two or more)3,4,…) cardiac cycles of the underlying rhythm.

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Sinoatrial BlockSinoatrial Block(Sino-Atrial Exit Block)(Sino-Atrial Exit Block)

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pause

In a sinus exit block the pause is equal to exactlytwo or more cardiac cycles of the underlyingrhythm.The electrical impulse from the SA node is blockedand not conducted to the atria.

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Sino Atrial Exit BlockSino Atrial Exit Block• Implies that there is delay or failure of a Implies that there is delay or failure of a

normally generated sinus impulse to exit the normally generated sinus impulse to exit the nodal region.nodal region.

• First First degree SA block:slowed conduction degree SA block:slowed conduction

• SecondSecond degree SA block:intermittent degree SA block:intermittent conduction conduction

1.Type 1 (Mobitz 1) 2.Type 2 (Mobitz 2)1.Type 1 (Mobitz 1) 2.Type 2 (Mobitz 2)

• ThirdThird degree SA block: complete conduction degree SA block: complete conduction failure failure

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X Y Z

X>YZ<2XZ<2Y

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SA Wenckebach

RosenRosenSinoatrial Block and Escape RhythmsSinoatrial Block and Escape Rhythms

Incomplete SA block Incomplete SA block is diagnosed when an is diagnosed when an occasional P wave is dropped from the occasional P wave is dropped from the normal P-QRS-T sequence on the ECG. normal P-QRS-T sequence on the ECG. There are no P waves on the ECG There are no P waves on the ECG

complete SA block complete SA block (sinus arrest). (sinus arrest). Usually, a lower pacemaker emerges in Usually, a lower pacemaker emerges in

complete SA block; if this pacemaker is complete SA block; if this pacemaker is within the AV node, the QRS complex is within the AV node, the QRS complex is narrow and results in an narrow and results in an "idiojunctional“escape rhythm at a rate of "idiojunctional“escape rhythm at a rate of 45 to 60 beats/min.45 to 60 beats/min.

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The pause is not equal to exactly two or more)3,4,…) cardiac cycles of the underlying rhythm.

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Sick sinus syndrome SSS also called sinus node dysfunction

(SND), is an umbrella term for a group of abnormal heart rhythms caused by a malfunction of the sinus node, the heart's primary pacemaker.

Bradycardia-tachycardia syndrome is a variant of sick sinus syndrome in which slow arrhythmias and fast arrhythmias alternate.

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Bradycardia-tachycardia syndrome

•All result in bradycardia

•Sinus bradycardia (rate of ~43 bpm) with a sinus pause

•Often result of tachy-brady syndrome: where a burst of atrial tachycardia (such as afib) is then followed by a long, symptomatic sinus pause/arrest, with no breakthrough junctional rhythm.

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Bradycardia-tachycardia syndrome

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Sick sinus syndrome is an indication Sick sinus syndrome is an indication for a for a permanent pacemakerpermanent pacemaker. . Pharmacologic treatment of atrial Pharmacologic treatment of atrial tachyarrhythmias carries the risk of tachyarrhythmias carries the risk of aggravating preexisting AV block or aggravating preexisting AV block or sinus arrest. sinus arrest.

Therefore, most patients should have Therefore, most patients should have pacemaker implantation pacemaker implantation beforebefore drugdrug therapy is begun.therapy is begun.

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Only Only single single shape shape PP

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Atrial DysrhythmiasAtrial Dysrhythmias Atrial dysrhythmias Atrial dysrhythmias have ECG features have ECG features

similar to those of sinus dysrhythmias,similar to those of sinus dysrhythmias, exceptexcept an atrial source serves as the an atrial source serves as the

pacemaker, producing pacemaker, producing P' waves P' waves that are that are different from the sinus P waves.different from the sinus P waves.

The The P'R interval P'R interval may also vary from the may also vary from the normal sinus PR interval, which normal sinus PR interval, which distinguishes these rhythms.distinguishes these rhythms.

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PAC non-compensatory pause

MACWandering pacemaker

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MAT

AV Blocks: AV Blocks: Divided in to incomplete and Divided in to incomplete and

complete blockcomplete block Incomplete AV block Incomplete AV block includesincludes

a. first-degree AV blocka. first-degree AV blockb. second degree AV blockb. second degree AV blockc. advanced AV blockc. advanced AV block

Complete AV blockComplete AV block,also known as third ,also known as third degree AV blockdegree AV block

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Location of the BlockLocation of the Block

Proximal to, in, or distal to the His bundle Proximal to, in, or distal to the His bundle in the atrium or AV node in the atrium or AV node

All degrees of AV blocks may be All degrees of AV blocks may be intermittent or persistentintermittent or persistent

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First Degree AV BlockFirst Degree AV BlockPR interval is prolonged 0.21- PR interval is prolonged 0.21-

0.400.40 seconds, but no R-R interval seconds, but no R-R interval changechange

Normal=0.10”-0,20”Normal=0.10”-0,20”

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Second-Degree AV BlockSecond-Degree AV Block

There is intermittent failure of the There is intermittent failure of the supraventricular impulse to be conducted supraventricular impulse to be conducted to the ventriclesto the ventricles

Some of the P waves are not followed by a Some of the P waves are not followed by a QRS complex.The conduction ratio (P/QRS QRS complex.The conduction ratio (P/QRS ratio) may be set at 2:1,3:1,3:2,4:3,and so ratio) may be set at 2:1,3:1,3:2,4:3,and so forthforth

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Types Of Second-Degree AVTypes Of Second-Degree AVBlock:I and IIBlock:I and II

Type I also is called Wenckebach Type I also is called Wenckebach phenomenon or Mobitz type I and phenomenon or Mobitz type I and

represents the more common typerepresents the more common type

Type II is also called Mobitz type II Type II is also called Mobitz type II

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Type I Second-Degree AV Type I Second-Degree AV Block: Wenckebach Block: Wenckebach

PhenomenonPhenomenon ECG findings ECG findings

1.Progressive lengthening of the PR 1.Progressive lengthening of the PR interval until a P wave is blockedinterval until a P wave is blocked2.Progressive shortening of the RR 2.Progressive shortening of the RR interval until a P wave is blockedinterval until a P wave is blocked3.RR interval containing the blocked 3.RR interval containing the blocked P wave is P wave is shortershorter than the sum of than the sum of two PP intervalstwo PP intervals 4343

Type II Second-Degree AVType II Second-Degree AVBlock:Block:

Mobitz Type IIMobitz Type II ECG findings ECG findings

1.Intermittent blocked P waves1.Intermittent blocked P waves2.PR intervals may be normal or 2.PR intervals may be normal or prolonged,but they remain constantprolonged,but they remain constant3.When the AV conduction ratio is 2:1,it is 3.When the AV conduction ratio is 2:1,it is often impossible to determine whether the often impossible to determine whether the second-degree AV block is type I or IIsecond-degree AV block is type I or II4. A long rhythm strip may help4. A long rhythm strip may help

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High-Grade or Advanced AV High-Grade or Advanced AV BlockBlock

When the AV conduction ratio is 3:1 or When the AV conduction ratio is 3:1 or higher, the rhythm is called advanced AV higher, the rhythm is called advanced AV blockedblocked

A comparison of the PR intervals of the A comparison of the PR intervals of the occasional captured complexes may occasional captured complexes may provide a clue provide a clue

If the PR interval varies and its duration is If the PR interval varies and its duration is inversely related to the interval between inversely related to the interval between the P wave and its preceding R wave (RP), the P wave and its preceding R wave (RP), type I block is likely type I block is likely

A constant PR interval in all captured A constant PR interval in all captured complexes suggests type II block complexes suggests type II block

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Complete (Third-Degree) AV BlockComplete (Third-Degree) AV Block

There is complete failure of the There is complete failure of the supraventricular impulses to reach the supraventricular impulses to reach the ventriclesventricles

The atrial and ventricular activities are The atrial and ventricular activities are independent of each otherindependent of each other

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ECG FindingsECG Findings

In patients with sinus rhythm and In patients with sinus rhythm and complete AV block, the PP and RR complete AV block, the PP and RR intervals are regular, but the P waves intervals are regular, but the P waves bear no constant relation to the QRS bear no constant relation to the QRS complexes complexes

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Bundle Branch BlockBundle Branch Block• Left Bundle Branch BlockLeft Bundle Branch Block1.Complete LBBB1.Complete LBBB2.Incomplete LBBB2.Incomplete LBBB

• Rigt Bundle Branch BlockRigt Bundle Branch Block1.Complete RBBB1.Complete RBBB2.Incomplete RBBB2.Incomplete RBBB

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Left Bundle Branch Block CriteriaLeft Bundle Branch Block Criteria

1.The QRS duration is 1.The QRS duration is > 120 ms> 120 ms2.Leads V5,V6 and AVL show broad and notched 2.Leads V5,V6 and AVL show broad and notched

or slurred R wavesor slurred R waves3.With the possible exception of lead AVL, the Q 3.With the possible exception of lead AVL, the Q

wave is absent in left-sided leadswave is absent in left-sided leads4.Reciprocal changes in V1 and V24.Reciprocal changes in V1 and V25.Left axis deviation 5.Left axis deviation maymay be present be presentDeep S in V1 no R inV1 &Deep S in V1 no R inV1 &R in V6 no S in V6R in V6 no S in V6

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Right Bundle Branch BlockRight Bundle Branch Block The diagnostic criteria includeThe diagnostic criteria include

1.QRS duration is 1.QRS duration is >120 ms>120 ms2.An rsr’,rsR’ or rSR’ pattern in lead 2.An rsr’,rsR’ or rSR’ pattern in lead V1V1

or or V2V2 and occasionally a and occasionally a wide and wide and notched R wave.notched R wave.

3.Reciprocal changes in 3.Reciprocal changes in V5,V6,I and V5,V6,I and AVL AVL

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Incomplete RBBBIncomplete RBBB

Criteria for incomplete RBBB are the Criteria for incomplete RBBB are the same as for complete RBBB except same as for complete RBBB except that the QRS duration is < 120 msthat the QRS duration is < 120 ms

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IRBBBIRBBB

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interventricular conduction delay interventricular conduction delay IVCDIVCD

Nonspecific Intraventricular Nonspecific Intraventricular Conduction Defects (IVCD)Conduction Defects (IVCD) QRS QRS duration >0.10s indicating slowed duration >0.10s indicating slowed conduction in the ventricles conduction in the ventricles

Criteria for specific bundle branch or Criteria for specific bundle branch or fascicular blocks not metfascicular blocks not met

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bilateral bundle branch blockbilateral bundle branch block (BBBB) interruption of cardiac (BBBB) interruption of cardiac impulses through both bundle impulses through both bundle branches, clinically indistinguishable branches, clinically indistinguishable from third degree (complete) heart from third degree (complete) heart block.block.

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Fascicular BlocksFascicular Blocks

The left bundle branch divides into The left bundle branch divides into two fasciclestwo fascicles1.Superior and anterior1.Superior and anterior2.Inferior and posterior2.Inferior and posterior

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Types Of Fascicular BlockTypes Of Fascicular Block

Left anterior fascicular blockLeft anterior fascicular block Left posterior fascicular blockLeft posterior fascicular block Bifascicular BlockBifascicular Block Trifascicular BlockTrifascicular Block

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Left Anterior Fascicular Block Left Anterior Fascicular Block Left axis deviation Left axis deviation , usually -45 to -90 degrees , usually -45 to -90 degrees

QRS duration usually <0.12s unless coexisting QRS duration usually <0.12s unless coexisting RBBB RBBB

Poor R wave progression Poor R wave progression in leads V1-V3 and in leads V1-V3 and deeper S waves in leads V5 and V6deeper S waves in leads V5 and V6

There is RS pattern with R wave in There is RS pattern with R wave in lead II > IIIlead II > III S wave in lead III > lead IIS wave in lead III > lead II

QR pattern in lead I and AVL,with QR pattern in lead I and AVL,with small Qsmall Q wave wave No other causes of left axis deviationNo other causes of left axis deviation

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LAFBLAFB

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LAFBLAFB

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LAFBLAFB

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Left Posterior Fascicular BlockLeft Posterior Fascicular Block Diagnostic Criteria includeDiagnostic Criteria include

1.QRS duration <120 ms1.QRS duration <120 ms2.No ST segment or T wave changes2.No ST segment or T wave changes3.3.Right axis deviation Right axis deviation (100 degree)(100 degree)

4.4.QRQR pattern in inferior leads ( pattern in inferior leads (II,III,AVFII,III,AVF) ) small q wavesmall q wave

5.5.RSRS pattern in lead pattern in lead I and AVL(small R with I and AVL(small R with deep S)deep S)6.No other causes of right axis deviation6.No other causes of right axis deviation

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LPFBLPFB

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Bifascicular Bundle Branch Bifascicular Bundle Branch BlockBlock

RBBB + LAFBRBBB + LAFBRBBB + LPFBRBBB + LPFBLBBBLBBBLAFB + 1LAFB + 1stst degree AV degree AVLPFB + 1LPFB + 1stst degree AV degree AV

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RBBB+ LAFBRBBB+ LAFB

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??

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RBBB + LPFBRBBB + LPFB

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??

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Trifascicular BlockTrifascicular Block

LBBB + 1LBBB + 1stst degree AV degree AV

RBBB + LAFB/LPBF +1RBBB + LAFB/LPBF +1stst degree AV degree AV

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TrifascicularTrifascicularRBBB+ LAFB + 1RBBB+ LAFB + 1stst degree degree

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??

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RBBB +LAFB +1RBBB +LAFB +1stst degree degree

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Indications for Permanent Indications for Permanent Pacing in Chronic Bifascicular Pacing in Chronic Bifascicular

and Trifascicular Blockand Trifascicular Block1.Class I1.Class I Intermittent third-degree AV block. Intermittent third-degree AV block. (B)(B) Type II second-degree AV block. Type II second-degree AV block. (B)(B)2.Class IIa2.Class IIa Syncope not proved to be due to AV block when Syncope not proved to be due to AV block when

other likely causes have been excluded, other likely causes have been excluded, specifically ventricular tachycardia (VT). specifically ventricular tachycardia (VT). (B)(B)

3.Class III3.Class III Fascicular block without AV block or symptoms. Fascicular block without AV block or symptoms.

(B)(B) Fascicular block with first-degree AV block Fascicular block with first-degree AV block

without symptoms. without symptoms. (B)(B)9393

Atropine will likely be ineffective in patients who have Atropine will likely be ineffective in patients who have undergone undergone cardiac transplantation cardiac transplantation because the transplanted because the transplanted heart lacks vagal innervation.heart lacks vagal innervation.

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TintinalliTintinalli As patients with atrial fibrillation can As patients with atrial fibrillation can

have a have a physiologicphysiologic rate response to rate response to trauma, sepsistrauma, sepsis, and , and other other disease disease process, other causes of hypotension process, other causes of hypotension should be investigated should be investigated beforebefore concluding that the rate is causing concluding that the rate is causing the hemodynamic deterioration.the hemodynamic deterioration.

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Dopamine 2-10 micg/kg/min Epinephrine 2-10 micg/minDobutamine 2-10 mic/kg/min Norepinephrine 2-10 mic/min

Nitroprosside 0.2-10 mic/kg/min Nitroglycerine 5-10micg/min

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ECG, Conduction disturbances

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