• Understanding of the anatomy and physiology of the cardiovascular system, basic rhythm interpretation, and electrical safety is necessary.

• Advanced cardiac life support knowledge and skills are needed.

• Familiarity with principles of electrophysiology is needed.

• The right ventricular (RV) leads V_1R through V_6R and left posterior leads V₇ through V₉ are unipolar leads in which the chest electrode serves as the “exploring” electrode or positive pole of the lead. These precordial leads view the heart from the vantage point of their electrode positions on the chest, similar to the standard precordial leads V₁ through V₆.

• For recordings of RV or left posterior leads, the three limb electrodes (right arm [RA], left arm [LA], left leg [LL]) also are required to create a central terminal (negative pole); one limb electrode (right leg [RL]) serves as the ground lead and is used to stabilize the electrocardiographic (ECG) recording.

• Accuracy in identification of anatomic landmarks for location of electrode sites and knowledge of the importance of accurate electrode placement are needed. Nurses must locate accurately the electrode positions for the standard 12-lead ECG because the same anatomic landmarks are used to locate the RV and left posterior leads. Accurate ECG interpretation is possible only when the recording electrodes are placed in the proper positions. Slight alterations of the electrode positions may distort significantly the appearance of the ECG waveforms and can lead to misdiagnosis.⁹ Reliable comparison of serial (more than two ECGs recorded at different times) ECG recordings relies on accurate and consistent electrode placement. An indelible marker is recommended for use with clear identification of the electrode locations to ensure that the same electrode locations are selected when serial ECGs are recorded.

• Nurses should be aware of body positional changes that can alter ECG recordings. Serial ECGs should be recorded with the patient in a supine position to ensure that all recordings are done in a consistent manner. Side-lying positions and elevation of the torso may change the position of the heart within the chest and can change the waveforms on the ECG recording.2,3 If a position other than supine is clinically necessary, notation of the altered position should be made on the tracing.

• Right precordial leads are useful in diagnosis of a RV myocardial infarction (MI).

• Nurses should be able to operate the 12-lead ECG machine. Calibration of 1 mV equals 10 mm and paper speed of 25 mm/s are standards used in clinical practice. For ST-segment analysis, filter settings of 0.05 to 100 Hz are recommended by the American Heart Association.¹² Any variation used for particular clinical purposes should be noted on the tracing. Specific information regarding configuring the ECG machine, troubleshooting, and safety features is available from the manufacturer and should be read before use of the equipment.

• Nurses should be able to interpret recorded ECGs for the presence or absence of myocardial ischemia, MI, and dysrhythmias so that patients can be treated appropriately. Patients with an acute inferior MI and RV involvement, determined by ST-segment elevation in the right precordial leads, are at high risk for high-degree AV block. Nurses should monitor patients closely for conduction disturbances and anticipate the need for temporary pacing. Patients with RV infarction are prone to hypotension and shock that responds to treatment with fluid resuscitation.

• Indications for recording a right precordial ECG are as follows:

• Indications for recording a left posterior ECG are as follows: