ECG MADE EASY (1) Year 4 Internal Medicine Notes OmpathStudy

ECG MADE EASY (1) Year 4 · Internal Medicine Collection: 4TH YEAR ALL NOTES / IMED / IMED 4.2 / Ngugi -- Slide 1 ElectroCardioGraphy medics.cc ECG made extra easy… Slide 2 Overview medics.cc Objectives for this tutorial What is an ECG? Overview of performing electrocardiography on a patient Simple physiology Interpreting the ECG Slide 3 Objectives medics.cc By the end of this tutorial the student should be able to: State a definition of electrocardiogram Perform an ECG on a patient, including explaining to the patient what is involved Draw a diagram of the conduction pathway of the heart Draw a simple labelled diagram of an ECG tracing List the steps involved in interpreting an ECG tracing in an orderly way Recite the normal limits of the parameters of various parts of the ECG Interpret ECGs showing the following pathology: MI, AF, 1st 2nd and 3rd degree heart block, p pulmonale, p mitrale, Wolff- Parkinson-White syndrome, LBBB, RBBB, Left and Right axis deviation, LVH, pericarditis, Hyper- and hypokalaemia, prolonged QT. Slide 4 What is an ECG? medics.cc ECG = Electrocardiogram Tracing of heart’s electrical activity Slide 5 Recording an ECG medics.cc Slide 6 Overview of procedure medics.cc GRIP Greet, rapport, introduce, identify, privacy, explain procedure, permission Lay patient down Expose chest, wrists, ankles Clean electrode sites May need to shave Apply electrodes Attach wires correctly Turn on machine Calibrate to 10mm/mV Rate at 25mm/s Record and print Label the tracing Name, DoB, hospital number, date and time, reason for recording Disconnect if adequate and remove electrodes Slide 7 Electrode placement medics.cc 10 electrodes in total are placed on the patient Firstly self-adhesive ‘dots’ are attached to the patient. These have single electrical contacts on them The 10 leads on the ECG machine are then clipped onto the contacts of the ‘dots’ Slide 8 Electrode placement in 12 lead ECG 6 are chest electrodes Called V1-6 or C1-6 4 are limb electrodes Right arm Left arm Left leg Right leg Ride Your Green Bike Remember The right leg electrode is a neutral or “dummy”! medics.cc Slide 9 medics.cc Electrode placement For the chest electrodes V1 4th intercostal space right sternal edge V2 4th intercostal space left sternal edge (to find the 4th space, palpate the manubriosternal angle (of Louis) Directly adjacent is the 2nd rib, with the 2nd intercostal space directly below. Palpate inferiorly to find the 3rd and then 4th space V4 over the apex (5th ICS mid-clavicular line) V3 halfway between V2 and V4 V5 at the same level as V4 but on the anterior axillary line V6 at the same level as V4 and V5 but on the mid-axillary line Slide 10 Recording the trace medics.cc Different ECG machines have different buttons that you have to press. Ask one of the staff on the ward if it is a machine that you are unfamiliar with. Ask the patient to relax completely. Any skeletal muscle activity will be picked up as interference. If the trace obtained is no good, check that all the dots are stuck down properly – they have a tendency to fall off. Slide 11 Electrophysiology medics.cc Slide 12 Electrophysiology medics.cc Pacemaker = sinoatrial node Impulse travels across atria Reaches AV node Transmitted along interventricular septum in Bundle of His Bundle splits in two (right and left branches) Purkinje fibres Slide 13 Overall direction of cardiac impulse medics.cc Slide 14 How does the ECG work? medics.cc Electrical impulse (wave of depolarisation) picked up by placing electrodes on patient The voltage change is sensed by measuring the current change across 2 electrodes – a positive electrode and a negative electrode If the electrical impulse travels towards the positive electrode this results in a positive deflection If the impulse travels away from the positive electrode this results in a negative deflection Slide 15 Direction of impulse (axis) medics.cc Towards the electrode = positive deflection Away from the electrode = negative deflection Slide 16 Types of Leads medics.cc Coronal plane (Limb Leads) Bipolar leads — Unipolar leads — l, l l, l l l aVL, aVR, aVF Transverse plane V1 — V6 (Chest Leads) Slide 17 Electrodes around the heart Slide 18 Leads How are the 12 leads on the ECG (I, II, III, aVL, aVF, aVR, V1 – 6) formed using only 9 electrodes (and a neutral)? Lead I is formed using the right arm electrode (red) as the negative electrode and the left arm (yellow) electrode as the positive Lead I + medics.cc Slide 19 Leads Lead I + medics.cc Slide 20 Leads Lead II is formed using the right arm electrode (red) as the negative electrode and the left leg electrode as the positive Lead II medics.cc Slide 21 Lead II medics.cc Slide 22 Leads medics.cc Lead III is formed using the left arm electrode as the negative electrode and the left leg electrode as the positive aVL, aVF, and aVR are composite leads, computed using the information from the other leads Slide 23 Leads and what they tell you medics.cc Limb leads Limb leads