DIAGNOSIS OFDIAGNOSIS OFCARDIAC CARDIAC RHYTHMSRHYTHMS

Lecture #2Lecture #2

I. Common TerminologyI. Common TerminologySupraventricular Supraventricular vs.vs. Ventricular Rhythms Ventricular Rhythms

• • The differential is made on the basis of QRS durationThe differential is made on the basis of QRS duration

• • If the QRS complex is If the QRS complex is narrownarrow (< 0.12 sec): (< 0.12 sec):– – TThe ventricular myocardium is depolarized rapidlyhe ventricular myocardium is depolarized rapidly– – The rhythm is The rhythm is supraventricularsupraventricular in origin in origin

• • If the If the QRS complex is QRS complex is widewide (> 0.12 sec): (> 0.12 sec): – – There is a There is a delay in the spread of the electrical delay in the spread of the electrical

activation throughout the ventricles activation throughout the ventricles – – The The origin of the rhythm may be in the origin of the rhythm may be in the ventricleventricle itselfitself

Premature Atrial ContractionPremature Atrial Contraction (PAC) (PAC)

• • P-waves differ from normalP-waves differ from normal

• • P-waves appear P-waves appear earlyearly

• • P-waves are followed by a normal-P-waves are followed by a normal-appearing QRS complexappearing QRS complex

MECHANISMMECHANISM

PVCPVC PAC PAC

Premature Ventricular ContractionPremature Ventricular Contraction (PVC) (PVC)

• • NONO P-waves present P-waves present

• • QRS complex is QRS complex is widewide

• • Ventricular TachycardiaVentricular Tachycardia (VT) (VT)

3 consecutive PVC’s, at a rate 3 consecutive PVC’s, at a rate 100 bpm 100 bpm

(Non-sustained VT - <30 sec)(Non-sustained VT - <30 sec)

I. Common Terminology I. Common Terminology (cont’d)(cont’d)

ArrhythmiaArrhythmia • • Generally referred to as aGenerally referred to as any rhythm other than normal ny rhythm other than normal

sinus rhythmsinus rhythm3 general mechanisms that can cause arrhythmias3 general mechanisms that can cause arrhythmias::Disorders of impulse formation:Disorders of impulse formation:1.1. Altered Altered AutomaticityAutomaticity2.2. TriggeredTriggered activity activityDisorders of impulse conduction:Disorders of impulse conduction:33. . Re-entryRe-entry

Mechanism of ArrhythmiasMechanism of Arrhythmias::

Re-entrant TachycardiaRe-entrant Tachycardia• • Rhythm is secondary to a Rhythm is secondary to a “loop”“loop” in the electrical in the electrical

circuitry circuitry (the re-entry pathway)(the re-entry pathway) resulting in resulting in tachycardiatachycardia

• Requires:Requires:1.1. Unidirectional block (with recovery)Unidirectional block (with recovery)

2.2. Slowed conduction through loopSlowed conduction through loop

• • It mayIt may occur within the SA node, the AV node, occur within the SA node, the AV node, oror actually any ectopic foci in the atria actually any ectopic foci in the atria oror ventricles ventricles

MECHANISMMECHANISM::

Re-entryRe-entryTachycardiaTachycardia

II. Diagnosing Cardiac RhythmsII. Diagnosing Cardiac Rhythms

A. A. Regular Supraventricular Regular Supraventricular RhythmsRhythms

1. Sinus Rhythm1. Sinus Rhythm

A.A. Normal Sinus RhythmNormal Sinus Rhythm •• Rate = 60 – 99 bpmRate = 60 – 99 bpm

B.B. Sinus BradycardiaSinus Bradycardia •• Rate Rate 59 bpm 59 bpm

C.C. Sinus TachycardiaSinus Tachycardia •• Rate Rate 100 bpm 100 bpm

Sinus Rhythm CriteriaSinus Rhythm Criteria::

1.1. EveryEvery QRS complex is QRS complex is precededpreceded by a P-waveby a P-wave

2.2. P-wavesP-waves appear appear normalnormal,, that is they are of that is they are of sinus sinus nodenode origin: origin:

A. A. Normal MorphologyNormal Morphology:: 1. P-wave duration 1. P-wave duration < 0.12 sec< 0.12 sec (< 3 boxes) (< 3 boxes) 2. P-wave height 2. P-wave height < 2.5 mm < 2.5 mm (< 2.5 boxes)(< 2.5 boxes)

B. B. Normal AxisNormal Axis:: 1. P-waves is 1. P-waves is uprightupright in in leads IIleads II, III & aVF, III & aVF 2. P-waves is 2. P-waves is negativenegative in in leadlead aVRaVR

2. Paroxysmal Atrial Tachycardia (PAT)2. Paroxysmal Atrial Tachycardia (PAT)

A.A. Re-entrant tachycardia of supraventricular origin, Re-entrant tachycardia of supraventricular origin,

with a rate of 120 with a rate of 120 –– 180 bpm 180 bpm (narrow complex)(narrow complex)

B.B. P-waves may P-waves may oror may not be visible, depending on may not be visible, depending on the ratethe rate

C.C. If present, P-waves are If present, P-waves are usually regularusually regular and and inverted in lead IIinverted in lead II (they may be seen before, (they may be seen before, during, during, oror after the QRS complexes) after the QRS complexes)

D.D. Usually idiopathic, but can also be seen in RHD, Usually idiopathic, but can also be seen in RHD, COPD, MVP & COPD, MVP & digitalis toxicitydigitalis toxicity

Paroxysmal Atrial TachycardiaParoxysmal Atrial Tachycardia

Paroxysmal Atrial TachycardiaParoxysmal Atrial Tachycardia

3. Atrial Flutter3. Atrial Flutter

A.A. Atrial rate Atrial rate ~~ 250 – 350 bpm 250 – 350 bpm

B.B. Characterized by rapid, undulatingCharacterized by rapid, undulating“flutter-waves”:“flutter-waves”:

1. Are best seen in 1. Are best seen in leads aVFleads aVF & & V1V1

2. Have a longer duration & a greater amplitude 2. Have a longer duration & a greater amplitude than a normal P-wavethan a normal P-wave

3. Have a 3. Have a saw-toothedsaw-toothed appearance appearance

C. There is C. There is alwaysalways some some degree of AV-blockdegree of AV-block present present (2:1, 3:1 (2:1, 3:1 oror variable), which is why the atrial rate is variable), which is why the atrial rate is always much greater than the ventricular ratealways much greater than the ventricular rate

Atrial FlutterAtrial Flutter

Atrial Flutter Atrial Flutter (cont’d)(cont’d)

D.D. Carotid sinus massageCarotid sinus massage –– may exaggerate the may exaggerate the

degree of AV-block & consequently slow down the degree of AV-block & consequently slow down the QRS rate, to assist with the QRS rate, to assist with the diagnosisdiagnosis

–– This makes the flutter-waves more obvious!This makes the flutter-waves more obvious!

4. Junctional Rhythm4. Junctional Rhythm

A.A. Impulses originate in theImpulses originate in the AV nodeAV node with retrograde & with retrograde & antegrade conductionantegrade conduction

B.B. QRS complexes are narrow & regular QRS complexes are narrow & regular (this is still (this is still considered supraventricular!)considered supraventricular!)

C.C. P-waves may be P-waves may be invertedinverted in leads II, III & aVF & in leads II, III & aVF & may occur may occur before, duringbefore, during oror afterafter the QRS complexes the QRS complexes

D.D. Junctional Junctional RateRate = = 40 40 –– 55 55 bpm bpm

E. E. This is usually an This is usually an escape rhythmescape rhythm due to SA node due to SA node dysfunction dysfunction oror digitalis toxicity!digitalis toxicity!

Junctional RhythmJunctional Rhythm

Junctional RhythmJunctional Rhythm

5.5. AV-Nodal Re-entrant AV-Nodal Re-entrant Tachycardia (AVNRT)Tachycardia (AVNRT)

A.A. One of the most common causes of PSVTOne of the most common causes of PSVT

B.B. P-waves may not be visible P-waves may not be visible oror may occur before, may occur before, during during oror after the QRS complexes after the QRS complexes

C.C. Two pathways usually exist: Two pathways usually exist: slowslow (anterograde (anterograde conduction) & conduction) & fastfast (retrograde conduction) (retrograde conduction)

D.D. More common in younger patientsMore common in younger patients

E.E. Abrupt onset & offset Abrupt onset & offset

6. AV Re-entrant Tachycardia 6. AV Re-entrant Tachycardia (AVRT)(AVRT)

A.A. Another common cause of PSVTAnother common cause of PSVT

A.A. Involves an Involves an “accessory pathway” (1:1500)“accessory pathway” (1:1500)

C.C. Usually utilizes the AV node as the Usually utilizes the AV node as the anterogradeanterograde & & the accessory pathway as the the accessory pathway as the retrograderetrograde limbs limbs ((Orthodromic Orthodromic AVRT) – accessory pathway may be AVRT) – accessory pathway may be ““concealedconcealed””

D.D. In 10%, impulse travels retrograde across AVN, In 10%, impulse travels retrograde across AVN, and anterograde over accessory pathway and anterograde over accessory pathway ((AntidromicAntidromic AVRT) – “ AVRT) – “pre-excitationpre-excitation” present” present

Pre-excitationPre-excitation

Pre-excitation:Pre-excitation: Impulse travels anterogradely th’ Impulse travels anterogradely th’ AV node + accessory pathway AV node + accessory pathway to ventriclesto ventricles

Examples include Examples include pre-excitationpre-excitation syndromes: syndromes:

– – Wolff–Parkinson–White syndrome Wolff–Parkinson–White syndrome

(pre-excitation + tacchycardia)(pre-excitation + tacchycardia)

– – Lown-Ganong-Levine (LGL) syndromeLown-Ganong-Levine (LGL) syndrome

– – ““Mahaim fiber tachycardias”Mahaim fiber tachycardias”

Wolff–Parkinson–White (WPW)Wolff–Parkinson–White (WPW)A.A. A supraventricular rhythm originating in the SA A supraventricular rhythm originating in the SA

node with normal & regular P-wavesnode with normal & regular P-waves

B.B. PR intervalPR interval is abnormally is abnormally shortshort (< 0.12 sec) (< 0.12 sec)

C.C. QRS is wideQRS is wide with a with a “slurred upstroke”“slurred upstroke” (AKA the (AKA the delta-wave)delta-wave)

D.D. Delta-waves are due to the Delta-waves are due to the accessory conduction accessory conduction pathway (pathway (bundle of Kentbundle of Kent)) from the atria to the from the atria to the ventricles, that bypasses the AV nodeventricles, that bypasses the AV node

E.E. Must manifest a Must manifest a tacchycardiatacchycardia at some point in time at some point in time

E.E. RRxx: Procainamide: Procainamide

Wolff–Parkinson–WhiteWolff–Parkinson–White

B. B. Irregular Supraventricular Irregular Supraventricular RhythmsRhythms

1. Sinus Arrhythmia1. Sinus Arrhythmia

2. Wandering Atrial Pacemaker 2. Wandering Atrial Pacemaker (WAP)(WAP)

A.A. Pacing is from various foci within the atriaPacing is from various foci within the atriaB.B. Heart rate <100 bpmHeart rate <100 bpmC.C. Contour Contour oror shape of P-waves vary from beat to shape of P-waves vary from beat to

beat, in a single lead beat, in a single lead (always try to look at lead II!)(always try to look at lead II!)D.D. Associated with variations of P-R & P-P intervals,Associated with variations of P-R & P-P intervals,

resulting in an resulting in an irregularly irregularirregularly irregular rhythm rhythmE. A common cause is rheumatic heart diseaseE. A common cause is rheumatic heart disease

F.F. SoSo, , DDxx Criterion Criterion:: Three consecutive P-waves with Three consecutive P-waves with

different morphologies, on a single EKG lead, different morphologies, on a single EKG lead, with a heart rate <100 bpmwith a heart rate <100 bpm

Wandering Atrial PacemakerWandering Atrial Pacemaker

Wandering Atrial PacemakerWandering Atrial Pacemaker

3. Multifocal Atrial Tachycardia 3. Multifocal Atrial Tachycardia (MAT)(MAT)

A.A. Multifocal Atrial Tachycardia (MAT)Multifocal Atrial Tachycardia (MAT) is similar to is similar to

wandering atrial pacemaker, wandering atrial pacemaker, exceptexcept that the heart that the heart

rate rate 100 bpm100 bpm

B.B. Again, you must have three different consecutive Again, you must have three different consecutive

P-wave morphologies on a given lead P-wave morphologies on a given lead (again, (again,

examine lead II!)examine lead II!)

C. C. Irregularly irregularIrregularly irregular rhythm rhythm

D.D. Usually associated with end-stage COPDUsually associated with end-stage COPD

E.E. RRxx:: Control the rate & treat the underlying problem Control the rate & treat the underlying problem

Multifocal Atrial TachycardiaMultifocal Atrial Tachycardia

4. Atrial Fibrillation4. Atrial Fibrillation

A.A. Random chaotic depolarizations of the atria at rates Random chaotic depolarizations of the atria at rates > 300 bpm> 300 bpm

B.B. NONO effective pumping of the atria takes place effective pumping of the atria takes place – – You loose You loose ~~25% of C.O., 25% of C.O., AKA the “atrial kick”AKA the “atrial kick”

C. C. Irregularly irregularIrregularly irregular rhythm rhythm

D.D. May occur in any clinical situation which causes May occur in any clinical situation which causes LAE, hyperthyroidism, LAE, hyperthyroidism, oror also with EtOH use also with EtOH use (“holiday heart”)(“holiday heart”)

E.E. RRxx:: Rate control & anti-coagulation Rate control & anti-coagulation

Atrial FibrillationAtrial Fibrillation

Atrial FibrillationAtrial Fibrillation

The ventricular rate can be either rapid or well-The ventricular rate can be either rapid or well-controlled, depending on the conduction through controlled, depending on the conduction through the AV nodethe AV node

C. C. Ventricular RhythmsVentricular Rhythms

…these are generally regular…!…these are generally regular…!

1. Idioventricular Rhythms1. Idioventricular Rhythms

A.A. Rhythm originates in the ventricles, giving Rhythm originates in the ventricles, giving rise to rise to widewide & & bizarrebizarre QRS complexesQRS complexes

B.B. The AV node & sometimes the SA node are The AV node & sometimes the SA node are not functioning normally!not functioning normally!

D.D. The axis of T-waves is in the The axis of T-waves is in the oppositeopposite direction of the QRS complexesdirection of the QRS complexes

E. E. RateRate = 20 = 20 –– 40 bpm 40 bpm

Idioventricular RhythmsIdioventricular Rhythms

Idioventricular Rhythm

2. 2. Accelerated Idioventricular Accelerated Idioventricular Rhythm (AIVR)Rhythm (AIVR)

A.A. Often develops following an Often develops following an acute MIacute MI!!

B.B. Occurs in short bursts & lasts < 20 sec Occurs in short bursts & lasts < 20 sec

C.C. RateRate = 40 = 40 –– 120 bpm 120 bpm

Accelerated Idioventricular Rhythm

3. Ventricular3. Ventricular Tachycardia (VT)Tachycardia (VT)A.A. Once again, you see Once again, you see broadbroad & & bizarrebizarre QRS QRS

complexes (> 0.12 sec)complexes (> 0.12 sec)B.B. Often with an abrupt onset Often with an abrupt onset C.C. RateRate 120 120 –– 140 bpm 140 bpmD.D. Can be Can be monomorphicmonomorphic oror polymorphicpolymorphic (Torsades)(Torsades)E.E. Look for Look for ventricular captureventricular capture & & fusion beatsfusion beats

– – Capture beatCapture beat:: a normal atrial beat “breaks through” a normal atrial beat “breaks through” BEFORE the ventricular beat has occurredBEFORE the ventricular beat has occurred

– – Fusion beatFusion beat:: the atrial beat “breaks through” DURING the atrial beat “breaks through” DURING the ventricular beatthe ventricular beat

Monomorphic Ventricular Tachycardia

Polymorphic Ventricular TachycardiaPolymorphic Ventricular Tachycardia((Torsades de Pointes)Torsades de Pointes)

Wide complex tacchycardia: SVT v/s VTWide complex tacchycardia: SVT v/s VT

SVTSVT VTVT

QRS durationQRS duration <0.14<0.14 >0.14>0.14

s/o AV dissociation (fusion, s/o AV dissociation (fusion, capture bts)capture bts)

absentabsent may be seenmay be seen

Response of vagal maneuversResponse of vagal maneuvers ++ --

Concordance of QRS Concordance of QRS complexes in V1-V6complexes in V1-V6

-- ++

Axis: extreme axis deviationAxis: extreme axis deviation rarerare may be seenmay be seen

h/o CADh/o CAD uncommonuncommon Usually presentUsually present

4. Ventricular4. Ventricular Fibrillation (VF)Fibrillation (VF)

A.A. Chaotic depolarization of the ventriclesChaotic depolarization of the ventricles

B.B. Loss of organized QRS complexesLoss of organized QRS complexes

C.C. Complete loss of the cardiac contractile functionComplete loss of the cardiac contractile function

D.D. Circulatory arrest comes about within secondsCirculatory arrest comes about within seconds

E.E. The most common cause of sudden cardiac The most common cause of sudden cardiac deathdeath

Ventricular FibrillationVentricular Fibrillation

Ventricular Fibrillation

General Rule for Arrhythmia RatesGeneral Rule for Arrhythmia Rates

RhythmRhythm Rate (bpm)Rate (bpm)• • Normal Sinus RhythmNormal Sinus Rhythm 60 60 –– 100 100• • Idioventricular Idioventricular “Escape”“Escape” Rhythm Rhythm 20 – 40 20 – 40• • Junctional Junctional “Escape”“Escape” Rhythm Rhythm 40 – 60 40 – 60• • Accelerated Idioventricular (AIVR)Accelerated Idioventricular (AIVR) 40 – 120 40 – 120• • Sinus Tachycardia (ST)Sinus Tachycardia (ST) 100 100 –– 150 150• • **SVT & Ventricular Tach. (VT)SVT & Ventricular Tach. (VT) 150 150 – 250– 250• • Atrial Flutter & Torsades de Pointes 250 – 350Atrial Flutter & Torsades de Pointes 250 – 350• • Atrial Fib. & Atrial Fib. & VentricularVentricular Fib. Fib. 350 – 350 –

450450

** Excludes ST, atrial fibrillation & atrial flutterExcludes ST, atrial fibrillation & atrial flutter

D. D. ArrhythmiasArrhythmias: : ReviewReview!!

RegularRegular Narrow-Complex Narrow-Complex TachycardiasTachycardias

1.1. Sinus TachycardiaSinus Tachycardia:: Normal P-waves, HR usually Normal P-waves, HR usually <150 bpm<150 bpm

2.2. Proxysmal Atrial TachycardiaProxysmal Atrial Tachycardia (PAT): (PAT): P-waves are P-waves are different from sinus (may be inverted) different from sinus (may be inverted) oror absent absent

3.3. Atrial FlutterAtrial Flutter:: Large “saw-toothed” Large “saw-toothed” flutter-waves,flutter-waves, +/+/–– variable AV-block variable AV-block

4.4. AV-Nodal Re-entrant TachycardiaAV-Nodal Re-entrant Tachycardia (AVNRT): (AVNRT): Most Most common form of PSVT, +/common form of PSVT, +/–– P-waves P-waves

5.5. AV Re-entrant TachycardiaAV Re-entrant Tachycardia (AVRT): (AVRT): A common A common form of PSVT, +/form of PSVT, +/–– P-waves, + accessory pathway P-waves, + accessory pathway

Irregularly IrregularIrregularly Irregular Narrow- Narrow-Complex TachycardiasComplex Tachycardias

1.1. Atrial FibrillationAtrial Fibrillation:: NoNo recognizable P-waves recognizable P-waves

2.2. Multifocal Atrial TachycardiaMultifocal Atrial Tachycardia (MAT): (MAT): Three (3) Three (3)

consecutiveconsecutive P-waves with different morphologies, P-waves with different morphologies,

usually associated with COPDusually associated with COPD

3.3. Any “regular” SVT with variable AV-blockAny “regular” SVT with variable AV-block::

ExamplesExamples:: PAT PAT oror a. flutter with variable AV-block a. flutter with variable AV-block

Approach to EKG InterpretationApproach to EKG Interpretation ALWAYS, ALWAYS, ALWAYS:ALWAYS, ALWAYS, ALWAYS:

1. 1. RateRate

2. 2. RhythmRhythm (includes analysis of intervals) (includes analysis of intervals)

3. 3. AxisAxis

4. 4. HypertrophyHypertrophy

5. 5. Ischemia, Injury, Ischemia, Injury, oror Infarct Infarct

Atrial (non-sinus) Rhythm

Multifocal Atrial Tachycardia

Atrial Flutter with 2:1 Conduction

Sinus Rhythm with Unifocal PVC’s

Atrial Fibrillation with a Slow Ventricular Response

Sinus Rhythm with Bigeminal PVC’s

Atrial Fibrillation with RVR

The EndThe End

Thank you for your attention!Thank you for your attention!

Questions?Questions?