Electrocardiogram Prepeared By Dr: Manal Moussa

Electrocardiogram Definition: ECG is a graphic record of the electrical currents that are generated by the heart.

Purposes: The nurse performs a 12- lead ECG to: 1- Provide information about the electrical system of the heart. 2- Record cardiac electrical activity for diagnostic or documentary reasons. 3- Diagnose myocardial infarction. 4- Detect cardiac enlargement. 5- Differentiate between different types of dysrrhythmias. 6- Determine the effects of administered drugs and/or electrolytes on the heart's electrical system.

Conductive system of the heart: *The Sino Atrial node (S.A node) has the highest rate of depolarization in the whole system. It starts each heart beat (pace maker). *From the S.A node, the impulse spreads to the atria through Bachmann's Bundle to the left atrium. *Stimulation of the atria produces the P wave on the ECG. After that a brief delay at the atrioventricular node (A.V node) to allow the atria sufficient time to squeeze additional blood into the ventricles.

*Then the impulse travels to the Bundles of His down the left and right bundle branches and terminates in the Purkinje fibers resulting in contraction of the ventricles. * The result of electrical stimulation of the ventricles produces QRS complex on ECG. *After that the relaxation of the cardiac muscle occurs which represent T wave in ECG.

-Interpretation of ECG leads: Bipolar limp leads:* Lead I (LI): When the ECG is attached to the right and left arms. It represents the difference in electrical impulse between these two points. Lead II (LII): When the ECG is attached to the right arm and left leg. It represents the difference in electrical impulse between these two points. Lead III (LIII): When the ECG is attached to the left arm and left leg. It represents the difference in

Records the changes in electrical current aVR: Located in right arm. Records the changes in electrical current occurring in the part of heart which faces the right shoulder. aVL: Located in left arm. Records the changes in electrical current occurring in the part of heart which faces the left shoulder. aVF: Located in left leg. in the part of heart which faces the left leg.

Chest or precordial leads: Chest leads: V1-----fourth intercostals space (ICS) at right sternal border. V2-----Fourth ICS at left sternal border. V3-----Midway between V2 and V4. V4-----Fifth ICS at midclavicular line. V5-----Left anterior axillary line at level of V4. V6-----Left midaxillary line at level of V4 horizontally.

Procedure: Rational Steps No I. Assessment: Asses the signs and symptoms of an alteration in cardiac status: -Vital signs. -Level of consciousness. -Neck vein distention. -Chest pain. -Peripheral circulatory disorders as: cyanosis, dependent edema. 1. II. Preparation: Environment: Maintain privacy of the patient. A.

-To save time and effort. -To maintain electrical safety. -To ensure accurate trace. Equipment: -ECG machine (12-lead). -ECG electrodes. -Trace paper. -Dry cotton sponge. -Basin and soap with shaver as needed Check: *The efficacy of the ECG machine and make sure it is connected into grounded alternative current outlet. *The cable and lead wires for any breaks. *Turn the machine on. *Set the lead selector to standby. B.

Reduces transmission of microorganisms Nurse: -Wash hands. C. -To reduce anxiety and gain his cooperation. -To prevent distortion of the ECG trace. -To provide minimal muscle activity. - To prevent shivering. - To assure good tracing. - Hair can interfere with conduction. -For appropriate conduction of impulse. Patient: 1- Explain procedure to the patient. 2- Instruct patient to the still without talking, relax and breathe normally and remove all jewelry or metals. 3- Place patient in supine position, and make sure that he does not touch the bedrails or foot board. 4-Expose only the necessary parts of the patient's legs, arms and chest. 5-Cleanse the sites for electrode placement, using soap, water, or alcohol pads. 6-Shave the area if needed. 7-Check electrodes for stickiness. 8-Prepare strap leads and chest sites by applying a small amount of electrode gel. D.

III. Implementation: Identify lead sites: 1. Limb leads: LI, LII, LIII, aVR, aVL, aVF. A. Strap electrodes around arm about 5cm above wrist, plate of lead being on outer arms. Strap electrodes around legs above ankles on inner leg. Fasten lead wires to limb electrodes, avoid bending or strain on wires and use correct lead to electrode connection. Chest leads: As mentioned before. B. Turn the switch that begins moving the Paper. Record each limb lead for 3-6 seconds. 2- -To see if any lead need to be repeated. Assess the quality of tracing. 3-

Post care: IV. Patient: A. Disconnect the electrodes and clean the gel off the patient using dry cotton. 1. -To be used as a document. Keep ECG strip in patient's file. 2. Environment: B. Return equipment. Nurse: C. -To prevent cross infection. Hand wash.

V. Documentation: Record in the patient's chart: -Patient's name. -Age. -Diagnosis. -Date. -Time of procedure.

Rate Number of big boxes 300 1 150 2 100 3 75 4 60 5 50 6 Rule of 300- Divide 300 by the number of boxes between each QRS = rate Rate Number of big boxes 300 1 150 2 100 3 75 4 60 5 50 6

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