Performing an EKG correctly helps clinicians capture accurate cardiac electrical activity and make timely clinical decisions. This guide walks through preparation, lead placement, artifact reduction, and documentation so you can record reliable tracings at the bedside.
Use the structured overview below to quickly compare core parameters, signal quality criteria, and common technical checks before you start a recording.
| Parameter | Optimal Value | What to Verify | Consequence of Poor Setup |
|---|---|---|---|
| Skin Preparation | Clean, lightly abraded, alcohol-dried | Remove oils, lotions, thick hair; check impedance if available | Increased impedance, baseline wander, poor lead contact |
| Electrode Position | RA right sternal, LA left sternal, LL left midclavicular, RL right lower | Match anatomic landmarks; ensure consistent placement for serial studies | Misplaced leads, incorrect axis interpretation, false arrhythmia detection |
| Cable Connection | Plug into correct port and selected leads on monitor/ECG machine | Check lead selector on machine matches limb and precordial picks | Missing leads, inverted polarity, garbled rhythm strip |
| Filter and Speed Settings | Default filter 0.05–150 Hz, paper speed 25 mm/s for routine, 50 mm/s for detailed analysis | Confirm machine settings and calibration signal before patient contact | Signal distortion, aliasing, misread heart rate or intervals |
Electrode Placement and Prep
Proper electrode placement is foundational for high-fidelity EKG acquisition. Position the four limb electrodes on the correct anatomic sites: right arm (RA) on the right sternal border at the second or third intercostal space, left arm (LA) on the left sternal border similarly, right leg (RL) as the ground reference typically on the right lower abdomen or ankle, and left leg (LL) at the left midclavibular line in the sixth intercostal space for the apex potential.
Precordial leads V1 through V6 should follow standardized positions: V1 at the fourth intercostal space right of the sternum, V2 at the fourth intercostal space left of the sternum, V4 at the fifth intercostal space midclavicular line, V3 midway between V2 and V4, V5 at the horizontal level of V4 in the anterior axillary line, and V6 at the same horizontal level in the midaxillary line.
Before attaching electrodes, clean the skin where adhesives will stick, lightly abrade areas with a gauze pad or exfoliating wipe, and dry thoroughly to lower impedance and minimize artifacts such as baseline wander and muscle noise.
Lead Selection and Machine Setup
Configure the machine for a standard 12-lead acquisition, ensuring limb and chest leads are correctly mapped on the lead selector and cable connectors. Confirm that filters are set to diagnostic ranges, calibration is verified with a standardization signal, and the recording system is prepared to capture data without automatic rejection of small deflections.
Select the appropriate recording mode based on clinical question: a routine diagnostic acquisition for baseline or undifferentiated symptoms, or a focused rhythm strip when monitoring known arrhythmias. Adjust paper speed or display grid so that intervals such as the PR segment and QT interval remain measurable and interpretable.
Document patient identifiers, setup parameters, and any unusual signal characteristics before proceeding with interpretation, enabling reliable correlation between technical factors and the final tracing.
Waveform Recognition and Measurement
Accurate recognition of P waves, QRS complexes, and T waves underpins correct interval measurements and axis determination. Use isoelectric baseline segments to anchor measurements of PR interval, QRS duration, and QT interval, and compare morphology across leads to infer chamber enlargement, ischemia, or conduction abnormalities.
Check for consistent R-wave progression across the precordial leads and confirm that lead orientations align with expected cardiac vectors. Measure axis by identifying leads with equiphasic or near equiphasic QRS complexes, then triangulate using orthogonal leads to estimate the frontal plane axis and flag significant deviations such as extreme axis deviation.
Leverage automated measurements as a first pass, but always manually verify key intervals, especially in the presence of arrhythmias, conduction defects, or artifact, to avoid misclassification of repolarization abnormalities or conduction delays.
Troubleshooting Artifacts and Poor Signal
Recognizing and correcting common artifacts improves diagnostic confidence and reduces the need for repeat studies. Typical culprits include poor skin preparation, loose cables, patient shivering or tremor, alternating current interference, and electrode displacement, each producing patterns such as wandering baseline, muscle tremor, or 60-cycle hum.
When baseline wander appears, re-prepare electrodes, confirm proper breathing patterns from the patient, and verify that filters are not over-aggressively removing low-frequency physiologic signals. For persistent noise, systematically check each connection, replace problematic electrodes, and isolate the system from electrical sources such as infusion pumps or faulty grounding.
Develop a consistent troubleshooting checklist so you can rapidly identify whether an issue is local to one lead, global across the tracing, or related to equipment settings, enabling efficient correction and preservation of recording quality.
Key Implementation Points
- Thoroughly clean and abrade the skin at each electrode site to lower impedance and reduce artifacts
- Confirm standardized lead positions for both limb and precordial electrodes before applying adhesives
- Verify machine settings, lead mapping, and calibration signal prior to recording patient data
- Use manual measurement and visual inspection to validate automated interval and axis calculations
- Systematically troubleshoot artifacts by checking cables, connections, patient factors, and electrical interference
- Document electrode placement, settings, and any anomalies to support accurate interpretation and continuity
FAQ
Reader questions
How do I know if my electrode placement is correct on an EKG?
Confirm correct placement by checking lead morphology: the P wave should be upright in limb leads except aVR, the QRS complexes should show appropriate R-wave progression across the precordial leads, and axis should fall within normal limits when frontal plane vectors are consistent.
What should I do if the baseline is wandering during an EKG recording?
Reposition electrodes with firmer skin preparation, clean and dry the sites, ensure cables are securely connected, and minimize patient movement or tremor; persistent wandering may require electrode replacement or checking for environmental interference.
Can I perform an EKG on patients with chest hair or pacemakers?
Yes, with adaptations: carefully shave electrode sites to reduce impedance, select proper lead systems for paced rhythms, verify capture and sensing parameters, and document device type and settings so the tracing is correctly interpreted.
How often should I check calibration and filters when performing routine EKGs?
Verify calibration using the built-in signal before each patient session, confirm filter settings match the selected mode (routine versus arrhythmia-focused), and document settings to ensure consistent, comparable tracings across studies.