How to Protect the Front End of ECGs From Defibrillators

ECGs are recordings of cardiovascular activity collected via the use of an electrocardiograph. An implanted cardioverter defibrillator is a device that is surgically implanted; the device depolarizes cardiovascular muscles and restores a heart rhythm to normal when an arrhythmia occurs. Since an electrocardiograph machine operates off of electricity, the device emits electromagnetic fields which can be interfered with by implanted defibrillators and vice versa. In addition, if a patient is exposed to the use of an external defibrillator, there are precautionary measures that must be used to keep the electrocardiograph equipment protected.

Things You'll Need

• 1- Electrocardiograph machine
• 3 Bipolar limb leads: Leads I, II, and III with negative electrodes
• 3 Unipolar limb leads: Leads I, II, and III with positive electrodes
• 6 Unipolar precordial leads (V1, V2, V3, V4, V5, and V6)
• ECG graph paper

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Instructions

• 1

  Creat Enithoven's Triangle by attaching the following limb leads: position Lead I with the negative electrode on the right wrist and Lead I on the left wrist. Attach Lead II with the negative electrode to the right wrist and Lead II with the positive electrode to the left ankle. Attach Lead III with the negative electrode on the left wrist, and Lead III with the positive electrode to the left ankle.

• 2

  Find the location on the patient's chest by feeling just below the sternum and clavicle and locating the first rib. Moving your hand downward, following the border of the sternum, feel the space between the first rib and the second; followed by the third and the forth. Move your hand to the space below the third rib and place the first unipolar precordial electrode on the chest (V1) to the left of the sternum.

• 3

  Position the next unipolar electrode (V2) to the right of the sternum and parallel to the V1 electrode. Position the V3 electrode below the fourth rib creating a 75-degree angle from the V2 electrode. Position the V4 electrode in the same space below the forth rib at a 60-degree angle from V2.

• 4

  Attach electrode V5 below the fourth rib at a 30-degree angle from V2, and attach electrode V6 in an aligned position with V5 in a perpendicular position to the center of the patient's armpit.

• 5

  Position the electrocardiograph machine at least 2 feet from the patient. Take the single wire that connects all of the leads and plug it into the electrocardiograph.

• 6

  Put the ECG graph paper into the electrocardiograph machine. Set the device to monitor mode by setting the high frequency limit between .5 Hz and 1 Hz and the low frequency to 40 Hz.

• 7

  To further protect the ECG front end from defibrillation, electroversion is performed externally on the patient. If the device does not have a built in protection, it will need to be unplugged from the wall during the process to keep the internal mechanisms working.