Rhythm recognition

Rhythm Interpretation

Rhythm Recognition (Interpretation)

Des Wade MSc; Advanced Paramedic

1

ObjectivesIdentify P,QRS,T waveforms on a normal ECG.Identify at least the following rhythms:Normal sinus rhythm (N.S.R)Sinus BradycardiaSinus TachycardiaN.S.R with premature ventricular contractions Ventricular FibrillationVentricular TachycardiaAsystole

Electrocardiogram ECG (Electrocardiogram) is a written record of the electrical activity of the heart

33T/10:1.1Define the term ECGDue to body fluids being good conductors, any changes in the electrical potential of the myocardium can be recorded on the surface of the body

Who should be monitored?All unconc. PatientsAll chest pain patientsAll trauma patientsKnown cardiac patientsAll breathless patientsPatients complaining of light-headedness/dizzinessPatients with abnormally fast or slow pulsesWhen a doctor requests monitoring

Chest Preparation Explain what you are about to do

Expose the monitoring area

Select and prepare the electrode site by wiping down the skin and drying it, if necessary

55T/10:1.7Describe the preparation of the patients chest area for cardiac monitoring avoiding the infliction of unnecessary discomfort

Chest Preparation Shave hairy chests with razor/clippers?Prepare skin with prep tape" or wipes?Attach leads to electrodes before placing them on the patient's chestApply electrodes in the correct position making sure they adhere wellRecord E.C.G.

66Electrodes L.A.S. uses adhesive electrodes that are disposableThey contain a metallic plate with a well of jelly which improves contact with the skinYou should make sure they are in date and are the type used by the serviceT/10:1.8Identify chest electrode positions and connect leads (No slide)

E.C.G. LeadsNumerous lead positions can be attached to the patient to view the heart, such as leads i, ii, iii, avr, avl, avfThe L.A.S. uses what is termed as lead ii and this is normally sufficient to identify the rhythm The word lead does not mean the wires connected to the patient i.e. Two lead, three lead, twelve lead ECG, but the electrical view of the heartLead ii looks at the left lateral surface of the heart as the left ventricle exerts more influence on the ECG than the right

Issues Effecting Monitoring Sweating, moist skinOily, dirty or scaly skinExcessive chest hairDried conductive gelPatient movement, muscle tremorInterference from electrical apparatus/Mobile phones Faulty equipment, low battery stateClinical intervention

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ARTIFACTS

Present as bizarre recordings They can be caused by a number of factors, eg: patient movement.

88T/10:1.11Define the term artefact and explain its significance when recording an ECG

Lead Placement

RYGNRide YourGreen NellyPatients RightPatients Left

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Each lead has one, and only one, positive electrode. We can think of the positive electrode as a camera or an eye. The view is from the positive electrode toward the negative electrode. The portion of the left ventricle that each leads sees is determined by the location of that positive electrode on the patients body.Different placements of the electrodes will yield different viewpoints.There are six positive electrodes on the chest, yielding six leads.There are four electrodes on the limbs from which the ECG machine makes another six leads.

So what do the 3 leads see?

MonitoringTypically Lead IIInferior wall of the myocardium

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The positive electrode for leads II, III, and aVF is attached to the left leg. The ECG monitor uses this one electrode as the positive electrode for all three leads.From that perspective, these leads look up and see the inferior wall of the left ventricle.NOTE: A heart model is helpful at this juncture, particularly to remind students that the heart does not sit straight up in the chest.

INFERIOR WALLInferior Wall

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NOTE: This is a posterior view of the heart.The portion of the heart that rests on the diaphragm is called the inferior wall.Leads II, III, and aVF, look up and see the inferior wall.When ST segment elevation is noted in II, III and aVF, suspect an inferior infarction.

The ECG paper.Time.25mm per second1 Small Square = 0.04 Seconds.5 Small Squares = 0.2 Seconds. 1 Large Square = 0.2 Seconds.5 Large Squares = 1 Second.

The ECG paper.Time.

= 0.04 Secondx 5 = 1 second

= 0.2 Second

Electrical Conduction System

Normal Sinus Rhythm

Main pacemaker

SA Node

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The Electrocardiogram ECGPWaverepresents depolarisation (electrical activity) of the atriais usually followed by contraction of the atria

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The Electrocardiogram ECGPR IntervalDepolarisation of the Atria and the delay at the AV Junction

PR Interval0.12 - 0.20 seconds = 3 - 5 small squares

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The Electrocardiogram ECGQRS Complexrepresents depolarisation (electrical activity) of the ventricles is usually followed by contraction of the ventriclesQRS duration0.08 - 0.12 seconds = 2 - 3 small squares

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The Electrocardiogram ECGTWaverepresents repolarisaton of the ventriclesor relaxation of the ventricles

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The Electrocardiogram ECGP Wave Depolarisation of the atriaQRS ComplexDepolarisation of the ventriclesT Wave represents Repolarisation of the ventricles

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IDENTIFYING RHYTHMS

P Waves ?Before every QRS ?PR Interval.12 - .2 sec ?QRS Complex ?Width < .12 sec ?Rate ?Rhythm ?Origin

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ECG IntervalsR - R IntervalDistance between each QRS ComplexQS ComplexIs when the entire complex is negatively deflectedConsidered equivalent to a wide Q waveHorizontal AxisSmall box 0.04 secLarge box 0.2 sec5 Large boxes 1 secondVertical AxisSmall box 0.1 mVPR Interval0.12 to 0.2 sec QRS Complex< 0.12 sec

ECG Intervals

Normal


QRS duration0.08 - 0.12 seconds = 2 - 3 small squares

Measuring the RhythmVentricular RateTriplicate method300 150 100 75 60 - 50R-R methoddivide 300 by # of large squares between consecutive R waves6 Second methodmultiply # of R waves in a 6 second strip by 10Rate meter unreliable!!!

Inherent Rates1SA Node60-1002AV Junction40-603Ventricles20-40

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QRS duration0.08 - 0.12 seconds = 2 - 3 small squares

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INTERVALSPR Interval.12 to .2 sec QRS Complex< .12 secR - R IntervalDistance between each QRS ComplexHorizontal AxisSmall box .04 secLarge box .2 sec5 Large boxes 1 secondVertical AxisSmall box .1 mV

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NORMAL SINUS RHYTHM

Main pacemaker

SA Node

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Electrical system of the HeartNormal Sinus Rhythm

A non shockable rhythm

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Normal Sinus Rhythm

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Sinus Bradycardia

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Sinus Tachycardia

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Premature Ventricular ContractionsPremature ventricular contraction (PVC), is a form of irregular heartbeat in which the ventricle contracts prematurely.

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Asystole

There is no electrical activityA non shockable rhythm

3535Case 5 focuses on the assessment and management of asystole. Asystole is a cardiac arrest rhythm associated with no discernible electrical activity on ECG ("flat line"). Successful resuscitation of a person in asystolic cardiac arrest occurs rarely. It happens only when rescuers stop, think, and ask Why did this person have this cardiac arrest at this time? Only if the cause of asystole is identified and treated in a timely manner will there be any reasonable possibility of survival. A large percentage of asystolic patients will not survive. Asystole occurs almost exclusively in severely ill persons. Often this rhythm represents the terminal rhythm of patients who have deteriorated from organ failure. Cardiac function has diminished until cardiac electrical and functional activity finally stop. The person has died. In such scenarios resuscitation fades as a high-priority action. Prolonged efforts are unnecessary, futile, often unethical, and ultimately dehumanizing if not demeaning. The asystole case therefore provides the most appropriate setting to discuss and understand more about ethics, when not to start resuscitative efforts, and indications for termination of the resuscitation attempt.

Asystole

3636

Pulseless Electrical Activity?Electrical activity with no pulse A non shockable rhythm

3737Idioventricular rhythms without a pulse are another form of PEA.

Hydrogen ions (Acidosis) HypokalemiaHyperkalemia Hypothermia Hypovolemia Hypoxia Tension pneumothoraxTamponade- CardiacTrauma Thrombosis - PulmonaryThrombosis - coronaryToxinsCauses of PEA

Lethal Cardiac DysrhythmiasThere are two lethal heart rhythms that may be corrected by early defibrillation:Ventricular Fibrillation (VF) Pulseless Ventricular Tachycardia (VT)

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HSE NAS Paramedic 3rd Ed. Upskilling ProgrammeIrish Ambulance Training InstituteVentricular Fibrillation

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Electrical system of the HeartVentricular FibrillationA shockable Rhythm

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HSE NAS Paramedic 3rd Ed. Upskilling ProgrammeIrish Ambulance Training InstituteVentricular Tachycardia

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Ventricular Tachycardia

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REMEMBER !!!NEVER Forget the Patient!!!ALWAYS Maintain their dignity at all times with effective blanketing. ALWAYS Monitor the patient`s vital signs, NOT JUST The ECG Monitor!

4444T/10:1.6Explain the importance of maintaining patient dignity

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Rhythm recognition