3 and 5 Lead ECG - CHSS eLearning

Three or five lead monitoring can be applied for use with both static and telemetry cardiac systems. The 3 or 5 lead systems are attached to electrodes which are applied to specific locations on the patient’s chest. It is important to ensure proper skin preparation prior to application of the skin electrodes.

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See Additional information for common problems associated with cardiac monitoring.

Having set up your specific monitoring system, we will now go on to consider how to interpret the cardiac rhythm using a systematic 6-step approach.

Skin preparation

Proper skin prep is essential to obtain good quality tracing:

Choose designated chest electrode placement sites
Avoid placing electrodes over bony prominences i.e. clavicles
To enhance electrode skin contact and patient comfort:
- Clip /shave excess chest hair in a 1-2 cm diameter of the designated electrode site, if necessary, with the patients consent
- With a dry swab, gently clean /abrade electrode sites to remove loose skin cells, body oil, sweat and improve skin/electrode contact
- If alcohol pad is used to cleanse skin, allow to site to dry, before electrode placement. ECG Electrodes are small sensor pads (self adhesive,disposable, pre gelled) applied on the skin to enable detection of the electrical activity of the heart, which is transmitted to the monitor, amplified and displayed as the ECG trace

3 lead Placement (I, II, or III):

Monitors one of the three leads:

RA: red electrode:
- placed under right clavicle near right shoulder, within the rib cage frame
LA: yellow electrode:
- placed under left clavicle, near left shoulder, within the rib cage frame
LL: green electrode:
- placed on the left side, below pectoral muscles, lower edge of left rib cage

5 lead Placement:

RA: red electrode:
- placed under right clavicle, near right shoulder, within the rib cage frame
LA: yellow electrode:
- placed under left clavicle, near left shoulder, within the rib cage frame
LL: green electrode:
- placed on the left side, below pectoral muscles, lower edge of left rib cage
V: white electrode:
- placed on the 4th intercostal space, at right sternal border
RL: black electrode:
- place on a non muscular surface on the lower edge of the right ribcage

How to set up a cardiac monitor:

Prepare Cardiac Monitor as directed by manufacturer

Attach designated lead cable and wires to electrodes
Select desired monitoring lead system – usually lead 11
Verify there is a clear ECG tracing & prominent QRS complex
Set Rate Alarm limits within safe parameters (acceptable to the individual patient’s clinical condition)
Confirm pre-determined arrhythmia analysis/default menu settings as per local protocol

The following are the common problems that may arise when the patient is on a cardiac monitor. See Common Cardiac Investigations: Good practice in ECG recording for more on common problems affecting ECG recordings.

		Causes	Solutions
Wandering Baseline:	QRS complexes difficult to interpret	Poor electrode skin contact Tension on cable or lead wires Respiratory movements Movement of the cable and leads with respiration	Check tension on lead wires / cable Reposition the patient Replace electrodes as required Select a different monitoring lead
Electrical (AC)Interference	AC artefact is characterised by fine rapid spikes which can obscure the components of ECG complexes	Incorrect grounding of electrical equipment. When multiple electric equipment is in use causing the interference e.g. pumps, beds, x-ray diathermy. Exposed or broken lead wires or cables	Identify the source Re-apply electrodes Check integrity of leads –cracks
Muscle Artifact	ECG baseline has an uneven coarsely jagged appearance obscuring the ECG tracing which may be continuous or intermittent	Caused by patient tensing – pain, fear, shock Medical related – tremors from Parkinsons, hypothermia	Encourage patient to relax Ensure filter ON Place electrodes on shoulders Re –apply electrode straps
False High Rate Alarm		Excessive muscle movement causing artefact potentials is interpreted by the monitor as QRS complexes High voltage QRS complexes – high gain – causing T waves to be sensed by the monitor as an R wave and doubling the rate Heart rate alarm not adjusted to above the patients own rate	Check tension on lead wires/cable Reposition the patient Replace electrodes as required Adjust the gain or identify another lead
False Low Rate Alarm		Disturbance in the transmission of electrical signal to the monitoring system Dry, loose or poorly connected electrode Low voltage QRS complexes –resulting in no detection of electrical activity Heart rate alarm not adjusted to below the patients own rate Disconnected or broken lead wire	Replace electrodes as appropriate Adjust the rate alarm parameters Increase gain setting Try alternative lead Replace broken leads

Telemetry Related Interference

Poor signal – straight lines/sharp spikes, weak battery
Transmitter used in outer range of the base receiver

Pulse point

Always refer to the manufacturer’s instructions for specific information related to the use of the monitoring system.

Principles of cardiac… 6 step approach

Page last reviewed: 30 Jul 2020

Heart Education Awareness Resource and Training through eLearning (HEARTe)

Skin preparation

3 lead Placement (I, II, or III):

5 lead Placement:

How to set up a cardiac monitor:

Pulse point