ecg & arrhythmias

PowerPoint Presentation

ECG &Cardiac Arrhythmias

1Prof. Dr. RS Mehta, MSND, BPKIHS

Introduction: The body acts as a conductor of electricity. As the wave of depolarization is transmitted throughout the heart , electrical currents spread into tissues surrounding the heart and to the surface of the body. The placement of electrodes on the skin on opposing sides of the heart enables the electrical current generated by the heart to be recorded.2Prof. Dr. RS Mehta, MSND, BPKIHS

What is an ECG ?The electrocardiogram (ECG/EKG) is a representation of the electrical events of the cardiac cycle.

Each event has a distinctive waveform, the study of which can lead to greater insight into a patients cardiac pathophysiology.3Prof. Dr. RS Mehta, MSND, BPKIHS

Cardio-diagnostic InvestigationsECG RecordingCardiac MonitoringTMT/Exercise ECG/Dobutamine Stress TestHolter monitoringEchocardiographyPericardiocentesisPulse OxymeteryChest X-rayCardiac AngiographyOthers: Pulse, BP, Heart Sound, CT, MRT etc


Purpose:ArrhythmiasMyocardial ischemia and infarctionPericarditisChamber hypertrophy / Cardiomegaly.Electrolyte disturbances (i.e. hyperkalemia, hypokalemia)Drug toxicity (i.e. digoxin)To provide vital information regarding the patients condition and progress( Death: flat ECG)


Anatomy & Physiology

Blood Flow through heartSuperior and Inferior Vena CavaRight AtriumRight VentriclePulmonary ArteryLungsPulmonary VeinLeft AtriumLeft VentricleAortaBody


Review Basic of ECG7Prof. Dr. RS Mehta, MSND, BPKIHS

Conduction System


Conduction SystemThe heart has a conduction system separate from any other systemThe conduction system makes up the PQRST complex we see on paperAn arrhythmia is a disruption of the conduction systemUnderstanding how the heart conducts normally is essential in understanding and identifying arrhythmias


SA NodeInter-nodal and inter-atrial pathwaysA-V NodeBundle of HisPerkinje Fibers

Conduction System


SA Node The primary pacemaker of the heartEach normal beat is initiated by the SA nodeInherent rate of 60-100 beats per minuteRepresents the P-wave in the QRS complex or atrial depolarization (firing)


AV NodeLocated in the septum of the heartReceives impulse from inter-nodal pathways and holds the signal before sending on to the Bundle of HisRepresents the PR segment of the QRS complex


AV NodeRepresents the PR segment of the cardiac cycleHas an inherent rate of 40-60 beats per minuteActs as a back up when the SA node failsWhere all junctional rhythms originate


QRS ComplexRepresents the ventricles depolarizing (firing) collectively. (Bundle of His and Perkinje fibers)Origin of all ventricular rhythmsHas an inherent rate of 20-40 beats per minute


Normal Impulse ConductionSinoatrial node

AV node

Bundle of His

Bundle Branches

Purkinje fibers


EKG TraceIsoelectric line (baseline) P-waveAtria firingPR intervalDelay at AV


EKG TraceQRSVentricles firingT-waveVentricles repolarizing


EKG TraceST segmentVentricle contracting Should be at isoelectric lineElevation or depression may be importantU wavePerkinje fiber repolarization?


Waveform AnalysisFor each strip it is necessary to go through steps to correctly identify the rhythmIs there a P-wave for every QRS?P-waves are upright and uniformOne P-wave preceding each QRS Is the rhythm regular?Verify by assessing R-R intervalConfirm by assessing P-P intervalWhat is the rate?Count the number of beats occuring in one minuteCounting the p-waves will give the atrial rateCounting QRS will give ventricular rate


1mm = 0.04sPaper speedsegments

QRS

P

PR IntQT Interval

1mm = 0.1mv


NormalHeart rate = 60 100 bpmPR interval = 0.12 0.20 secQRS interval

ecg & arrhythmias

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