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Reversal of the Left Arm and Right Leg Electrodes

Image 7 of 22 in Series "Recognition of Errors in ECG Recordings"

Description

Image 7 demonstrates the effect of the reversal of the left arm (LA) and right leg (RL) electrodes. Lead I is recorded as identical to lead II. Lead II is unchanged since the right arm (RA) and left leg (LL) electrodes are correctly positioned. The voltages recorded by the LA and LL electrodes are nearly equal, making lead III almost isoelectric. Lead aVR is directed toward the correctly positioned RA electrode, resulting in a normal aVR that is recorded as an inverted lead II. Due to the inferior location of the LA electrode, leads aVL and aVF are identical.

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This image is part of the series "Recognition of Errors in ECG Recordings"

Other images in this series

Reversal of the Arm Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 1 demonstrates the effect of reversal of the arm electrodes. Leads I and aVL are directed opposite the mean cardiac vector, resulting in the characteristic findings of negative P waves, QRS complexes and T waves in these leads and right axis deviation. Since the left leg electrode remains correctly positioned, leads II and II are reversed, with lead II recorded as lead III and lead III recorded as lead II. Likewise, leads aVR and aVL are reversed. Lead aVF is unchanged.

Reversal of the Arm Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 2 was recorded with correct lead placement. An additional finding in both ECGs is first degree AV block.

Reversal of the Right Arm and Right Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 3 demonstrates the effect of the reversal of the right arm (RA) and right leg (RL) electrodes. The inferior location of the RA electrode causes the RA and left leg (LL) electrodes to record nearly the same voltages, resulting in the characteristic finding of low amplitude QRS complexes and an almost isoelectric recording in lead II. Since the position of the left arm (LA) electrode is unchanged, lead I is recorded as an inverted lead III and lead III is unaffected. Lead aVL is nearly identical to lead I and leads aVR and aVF are identical.

Reversal of the Right Arm and Right Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 4 was recorded with correct lead placement. It is a normal ECG with upright QRS complexes in leads I and II with increased QRS amplitude in lead II.

Reversal of the Left Arm and Left Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 5 demonstrates the effect of the reversal of the left arm and left leg electrodes. Lead I is recorded as lead II and lead II is recorded as lead I. Lead III is an inverted lead III. Leads aVF and aVL are reversed and lead aVR is unaffected by reversal of the left sided electrodes. In this example, this electrode reversal results in the incorrect identification of an old lateral infarct.

Reversal of the Left Arm and Left Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 6 shows an old inferior infarct after correction of the electrode reversal. In both ECGs, the rhythm is sinus bradycardia. A single premature ventricular complex is recorded in Image 6.

Reversal of the Left Arm and Right Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 8 was recorded with correct lead placement. In both Images 7 and 8, the precordial leads are unaffected by this limb lead reversal. A possible old anteroseptal infarct is shown in both ECGs. Voltage criteria for left ventricular hypertrophy and artifact are present in Image 7 and a nonspecific T wave abnormality is present in Image 8.

Reversal of the V1 and V3 Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 9 shows a large R wave in lead V1 and an abrupt decrease in R wave amplitude with a larger S wave in lead V3 when compared to leads V2 and V4. Reversal of the V1 and V3 electrodes results in a predominantly positive QRS complex in lead V1 and a predominantly negative QRS complex in lead V3 as ventricular depolarization proceeds from the patient’s right to left side.

Reversal of the V1 and V3 Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 10 was obtained with correct lead positioning, resulting in a predominantly negative QRS complex in lead V1 as ventricular depolarization proceeds toward the patient’s left and away from this lead and a large R wave in lead V3 as depolarization proceeds toward the other precordial leads. Both ECGs are otherwise normal. Rhythm is sinus bradycardia with sinus rates of 46/min and 49/min, respectively, in Images 9 and 10.

Reversal of the V1 and V3 Electrodes in a Patient with Right Bundle Branch Block

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Reversal of leads V1 and V3 is shown in Image 11 in a patient with right bundle branch block (RBBB). The familiar rSR’ waveform of RBBB occurs in lead V3 whereas the waveform recorded in lead V1 consists of an R wave followed by a large S wave.

Reversal of the V1 and V3 Electrodes in a Patient with Right Bundle Branch Block

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Correct lead positioning is shown in Image 12, with an rSR’ waveform in lead V1 and the RS waveform in lead V3 due to the rightward direction of the final phase of ventricular depolarization in RBBB. Rhythm is sinus bradycardia with sinus rates of 53/min and 49/min, respectively, in Images 11 and 12. Left axis deviation is present in both ECGs.

Reversal of the V2 and V3 Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 13 shows QS complexes in leads V1 and V3 and prominent R waves in leads V2 and V4. A predominantly negative QRS complex is recorded by the more superiorly placed V3 electrode whereas a more positive QRS complex is recorded by the more inferiorly positioned V2 electrode.

Reversal of the V2 and V3 Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 14 is recorded with correct electrode placement. QS complexes, consistent with an old anteroseptal infarct, are recorded in leads V1 and V2. An Rs complex is recorded in lead V3 as ventricular depolarization proceeds inferiorly and to the patient’s left. The sixth and eighth complexes are premature atrial complexes.

Reversal of the V1 and V6 Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 15 demonstrates the effect of reversing the V1 and V6 electrodes. The results are positive QRS complexes in lead V1, negative QRS complexes in lead V6 and an abrupt loss of R waves from lead V1 to V2 and from V5 to V6. In this example, the QS complexes in lead V2 are consistent with an old anteroseptal infarct and this finding is not affected by the lead reversal.

Reversal of the V1 and V6 Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG recorded after correct positioning of the precordial electrodes is shown in Image 16. It shows an old anteroseptal and anterior infarct with normal R wave progression from lead V4 to V6.

Reversal of the Arm Electrodes and of V1 and V6

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 17 demonstrates the effect of reversal of the arm electrodes and the V1 and V6 electrodes. Arm electrode reversal results in negative P waves, QRS complexes and T waves in leads I and aVL and right axis deviation. Since the left leg electrode remains correctly positioned, leads II and II are reversed, with lead II recorded as lead III and lead III recorded as lead II. Likewise, leads aVR and aVL are reversed. Lead aVF is unchanged. Large R waves are present in leads V1-5 and an abrupt decrease in R wave amplitude is present in lead V6. Ventricular depolarization proceeds to the patient’s left side, away from the incorrectly placed V6 electrode, resulting in qS complexes in lead V6, and toward the incorrectly placed V1 electrode, resulting in prominent R waves in lead V1.

Reversal of the Arm Electrodes and of V1 and V6

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 18 was recorded with correct electrode placement, resulting in a normal ECG.

Misplacement of the Right Arm, Left Arm and Left Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 19 demonstrates the effect of the misplacement of three electrodes. The right arm (RA) electrode is placed on the left arm, the left arm (LA) electrode is on the left leg and the left leg (LL) electrode is positioned on the right arm. Lead I (RA to LA) is recorded as lead III, lead II (RA to LL) is recorded as an inverted lead I and lead III (LA to LL) is recorded as inverted lead II. Lead aVR is recorded as lead aVL, lead aVL as lead aVF and lead aVF as lead aVR. The precordial leads are unaffected. Rhythm is sinus bradycardia.

Misplacement of the Right Arm, Left Arm and Left Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

The ECG in Image 20 was recorded with correct lead placement. Rhythm is sinus bradycardia. The ECG is normal.

Misplacement of the Right Arm, Left Arm and Right Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 21 demonstrates the effect of the misplacement of three electrodes. The right arm (RA) electrode is placed on the right leg, the left arm (LA) electrode is on the right arm and the right leg (RL) electrode is positioned on the left arm. Lead I (RA to LA) records an inverted lead II, lead II (RA to LL) is nearly isoelectric due to the close proximity of the leg electrodes and lead III (LA to LL) is recorded as lead II. Leads aVR and aVF record similar positive deflections due to the inferior location of the misplaced RA electrode and the correctly placed LL electrodes, respectively. Lead aVL is recorded as lead aVR due to the positioning of the LA on the right arm.

Misplacement of the Right Arm, Left Arm and Right Leg Electrodes

by: Joe B. Calkins, Jr., M.D.; Kathryn E. Lichtenfels, R.N., B.S.N.

Image 22 is a normal ECG that was recorded with correct lead placement