*BASIC ELECTROCARDIOGRAPHYINTERPRETATION AND MANAGEMENT

THE ECG waveforms P, QRS, and TTHE ECG segments and intervals PR interval,QRS duration, ST segment, QT interval.VARIOUS QRS CONFIGURATIONS*

*RATE MEASUREMENT The horizontal axis represents time. The vertical axis represents amplitude or voltageSix-second method a. Most ECG paper in use today is printed with 1-sec or 3-sec markers on the top or bottom of the paper b. To determine the ventricular rate, count the number of R-R intervals within a period of 6 seconds and multiply that number by 10 to find the number of complexes in 1 minute Method 1:Method 2:||||||||12345678 Calculating heart rate. Method 1: Number of R-R intervals in 6 seconds x 10 (e.g., 8 x 10 = 80/min. Method 2: Number of large boxes between QRS complexes divided into 300 (e.g., 300 divided by 4 = 75/min). Method 3: Number of small boxes between QRS complexes divided into 1500 (e.g., 1500 divided by 18 = 84/minSmall boxes

*Hardwire monitoringMONITORING AND LEAD PLACEMENTTYPES OF INTERFERENCEMuscle TremorsPatient Movement

*Loose Electrode60-Cycle InterferenceStraight LineTYPES OF INTERFERENCELoss of reception Bio-Telemetric Interference

*CHARACTERISTICS OF SINUS RHYTHMRate 60 to 100 beats/minRhythm RegularP waves Uniform in appearance, positive (upright) in lead II, one precedes each QRS complexPR interval 0.12 to 0.20 sec and constant from beat to beatQRS duration .10 sec or lessSinus rhythm at 70 beats/minSINUS BRADYCARDIARate 54 beats/minuteRhythm RegularP waves SinusPR interval 0.20 secondQRS duration 0.06 to 0.08 secondNote A notched P wave is usually indicative of left atrial hypertrophy

*CHARACTERISTICS OF SINUS TACHYCARDIARate 101 TO 180 beats/minRhythm RegularP waves Uniform in appearance, positive (upright) in lead II, one precedes each QRS complex; at very fast rates, it may be difficult to distinguish a P wave from a T wavePR interval 0.12 to 0.20 sec and constant from beat to beatQRS duration 0.10 sec or lessSinus tachycardia at 129 beats/minRate 60 beats/minRhythm irregularP waves Normal in configuration; precede each QRSPR interval 0.12 to 0.14 secondQRS duration 0.06 to 0.08 secondSINUS ARRHYTHMIA

*NORMAL SINUS RHYTHM WITH SINUS ARRESTR-R regularityR-R REGULARITY INTERRRUPTED; rhythm does not resume on time after pauseNORMAL SINUS RHYTHM WITH SINUS BLOCKRate Basic rhythm 94 beats/minuteRhythm Basic rhythm regular, irregular during pause P waves Normal in normal in basic rhythm; absent during pausePR interval 0.16 to 0.18 second in basic rhythm; absent during pauseQRS duration 0.06 to 0.08 second in basic rhythm; absent during pauseRate Basic rhythm 84 beats/minuteRhythm Basic rhythm regular, irregular during pause P waves Normal in normal in basic rhythm; absent during pausePR interval 0.16 to 0.18 second in basic rhythm; absent during pauseQRS duration 0.08 to 0.10 second in basic rhythm; absent during pause

*JUNCTIONAL RHYTHMRhythm : RegularRate: : 50 beats/minuteP waves: Hidden in QRS complexPR interval: Not measurableQRS complex: :Normal 0.06 to 0.08 secondRhythm : RegularRate: : 65 beats/minuteP waves: Hidden in QRS complexPR interval: Not measurableQRS complex: :Normal 0.06 to 0.08 secondJUNCTIONAL TACHYCARDIA

*CHARACTERISTICS OF ATRIAL FLUTTERRate Atrial rate 250 to 450 beats/min, typically 300 beats/min; ventricular rate variable --- determined by Av blockage; the ventricular rate will usually not exceed 180 beats/min because of the intrinsic conduction rate of the AV junction.Rhythm Atrial regular, ventricular regular or irregular depending on AV conduction/blockage P waves No identifiable P waves; saw-toothed flutter waves are presentPR interval Not measurableQRS duration Usually less than 0.10 sec but may be widened if flutter waves are buried in the QRS complex or an intraventricular conduction delay exists

*CHARACTERISTICS OF ATRIAL FIBRILLATIONRate Atrial rate usually greater than 400-600 beats/min; ventricular rate variableRhythm Ventricular rhythm usually irregularly irregularP waves No identifiable P waves; fibrillatory waves present. Erratic, wavy baseline PR interval Not measurableQRS duration Usually less than 0.10 second but may be widened if an intraventricular conduction delay exists

*CHARACTERISTICS OF FIRST-DEGREE AV BLOCKRate Usually within normal range but depends on underlying rhythmRhythm RegularP waves Normal in size and shape; one positive (upright) P wave before each QRS in leads II, III, and aVFPR interval Prolonged (greater than 0.20 sec) but constantQRS duration Usually 0.10 sec or less unless an intraventricular conduction delay existsCHARACTERISTICS OF FIRST-DEGREE AV BLOCKThe AV node holds each sinus impulse longer than normal before conducting if through to ventricles. Each impulse is eventually conducted . Once into the ventricles, conduction proceeds normally.

*FIRST DEGREE AV BLOCKRhythm interpretation: Usually regularRate: That of underlying sinus rhythm; atrial and ventricular rates will be the sameP waves: Sinus; one P wave to each QRS complexPR interval: Prolonged (greater than 0.20 secondQRS complex: Normal (0.10 second or less)SECOND-DEGREE AV BLOCK (MOBITZ I)Rhythm interpretation: Atrial:RegularVentricular:IrregularRate: Atrial:That of underlying rhythmVentricular:Depends on number of impulses conducted though AV node; less than atrial rate P waves: Sinus originPR interval: Varies; progressively lengthens until a P wave is not conducted (P wave occurs without a QRS complex); a pause follows the dropped QRS complexQRS complex: Normal (0.10 second or less)

*SECOND-DEGREE AV BLOCK (MOBITZ II)Rhythm interpretation: Atrial:RegularVentricular:Usually regular but may be irregular if AV conduction ratios varyRate: Atrial:That of the underlying rhythmVentricular:Depends on number of impulses conducted though AV node; less than atrial rate P waves: Sinus; two or three P waves (sometimes more) before each QRS complexPR interval: May be normal or prolonged; remains constantQRS complex: Normal is block at AV node or bundle of His; wide if block in bundle branchesRhythm interpretation: Atrial:RegularVentricular:RegularRate: Atrial:That of the underlying rhythmVentricular:40 to 60 beats/minute if paced AV junction; less than 40 beats/minute of paced by ventricles; ventricular rate less than atrial rateP waves: Sinus P waves present with no constant relationship to QRS complex (P waves found marching through QRS complexes and T waves)PR interval: Varies greatlyQRS complex: Normal if block at AV node or bundle of His; wide if block in bundle branchesTHIRD-DEGREE AV BLOCK (COMPLETE HEART BLOCK)

*PACEMAKERSAV sequential pacingAtrial pacingVentricular pacing100% Ventricular-paced rhythm

*Sinus tachycardia with multiform PVCsSinus rhythm with a run of VT and one episode of coupletsSinus tachycardia with frequent uniform PVCsRate Usually within normal range but depends on underlying rhythmRhythm Essentially regular with premature beats; if the PVC is an interpolated PVC, the rhythm will be regularP waves Usually absent or, with retrograde conduction to the atria, may appear after the QRS (usually upright in the ST-segment of T wave)PR interval None with the PVC because the ectopic originates in the ventriclesQRS duration Greater than 0.12 sec, wide and bizarre, T wave frequently in opposite direction of the QRS complexCHARACTERISTIC OF PREMATURE VENTRICULAR COMPLEXES (PVCs)

*CHARACTERISTICS OF MONOMORPHIC VENTRICULAR TACHYCARDIARate 101 to beats/minRhythm Essentially regularP waves May be present or absent; if present, they have no set relationship to the QRS complexes appearing between the QRSs at a rate different from that of the VTPR interval NoneQRS duration Greater than 0.12 sec, often difficult to differentiate between the QRS and T wavePolymorphic Ventricular Tachycardia or Torsades de pointes

COARSE VFCHARACTERISTIC OF VENTRICULAR FIBRILLATION (VF)RateCannot be determined because there are no discernible waves or complexes to measureRhythmRapid and chaotic with no pattern or regularlyP wavesNot discerniblePR intervalNot discernibleQRSNot discernible*Fine VF

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