Diagnosis and practical implications of ECG lead reversal: Anesthesiologist perspective.

Dear Editor,

Most electrocardiographic (ECG) abnormalities during the perioperative period are diagnosed and managed appropriately by the anesthesiologist. Abnormal ECG owing to the reversal of limb lead could also happen either by manual error or faulty equipment.[1] Here, we report a case of ECG lead reversal and discuss the important relevant points for practicing anesthesiologists.

A 24–year-old female patient was planned for puerperal sterilization. During preoperative evaluation by an experienced anesthesiologist, she was found to have a pulse rate of 116 bpm with regular rhythm and blood pressure of 124/82 mmHg. Other clinical examination including cardiovascular system was unremarkable. Her hemoglobin level was 10.2 g/dl.Considering the differential diagnosis of anxiety, hyperthyroidism, and cardiac abnormalities, an ECG was asked for further evaluation of tachycardia.

The ECG showed heart rate of 103 bpm, with right axis deviation, aVR uptake, ST depression in V3, V4, V5, V6, and T wave inversions in V1–V4 [Figure 1a]. Although the automatic ECG machine (MAC 1200ST series, GE medical systems) interpretation was “suspect arm lead reversal,“ these findings were suggestive of non ST-elevation myocardial infarction (NSTEMI), which warrants further investigations.[23] In addition, the clinical features were not correlating, and the ECG was repeated and found to be normal [Figure 1b]. Our case strongly emphasizes the fact that an ECG should always be correlated clinically.

Figure 1

(a) ECG with lead reversal and suspected NSTEMI. (b): Normal ECG

If ECG findings of NSTEMI had been present with non-specific cardiac symptoms, any anesthesiologists would have asked for further cardiac evaluation. On the first look, we could not have diagnosed the lead reversal. Only after reading the ECG machine interpretation, we could diagnose the ECG limb lead reversal [Table 1]. This was simulated in the various anesthesia workstations, and we noticed that surprisingly none of the perioperative multiparametric monitor (equipped with arrhythmia analysis) used in the perioperative period gives alarm for limb lead reversal. On several occasions, the ECG monitoring is disconnected and reconnected especially during the change of position (eg., supine to prone) in operating room. In those situations, sudden change in the ECG is a serious cause of concern for anesthesiologist.

Table 1

Alterations observed in ECG caused by common leads misplacement in normal ECG

Leads reversed	ECG pattern observed	Clinical misinterpretation
Right arm, Left arm	Inverted P waves in II, III, aVF; large q-wave in I, aVL; leads I and aVL appear as inverse of V5-6	Non sinus atrial rhythm; Old lateral wall myocardial infarction
Right arm, Left lower limb	Inverted P waves II, III, aVF; large q waves II, III, aVF	Non sinus atrial rhythm; Old inferior wall myocardial infarction
Left arm, Left lower limb	Insignificant q-waves in III	Nil
Right lower limb, Left lower limb	No change	Nil
Left arm, Right lower limb	Low voltage lead III	Nil
Right arm, Right lower limb	Diffuse low voltage in all limb leads, especially lead II; non-sinus atrial or junctional rhythm	Conditions described by diffuse low voltage complexes
Reversal of precordial leads	Break in normal R-wave progression from V1-6	Mirror image dextrocardia or posterolateral infarction

Therefore, we suggest the manufacturers to incorporate the lead reversal alarm in the arrhythmia analysis of ECG monitoring. In addition, every anesthesiologist should be aware of the diagnostic criteria for ECG limb lead reversal.

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Conflicts of interest

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