Paucis Verbis: Right and posterior ECG leads

ECG EKG machine

A standard 12-lead ECG can be very telling for patients with chest pain or shortness of breath. A right ventricular (RV) and posterior wall infarct, however, can present very subtly. You can obtain special right-sided (V1R-V6R) and posterior leads (V7-V9), if you are concerned. What are the indications for obtaining right-sided and posterior ECG leads?

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Addendum 3/11/11:

Right sided ECG leads (V1R-V6R) are positioned in a mirror image fashion from the standard 12-lead precordial leads.
Posterior ECG leads (V7-V9) are applied by moving V4-V6 in the posterior positions.

By |2021-10-16T19:28:52-07:00Mar 11, 2011|ALiEM Cards, ECG|

Paucis Verbis: Sgarbossa’s Criteria with LBBB


It is difficult to determine if a patient with a left bundle branch block (LBBB) has an acute myocardial infarction (AMI) because ST segments are “appropriately discordant” with the terminal portion of the QRS. That means if the QRS complex is negative (or downgoing), the ST segment normally will be positive (or elevated). Similarly if the QRS complex is positive (or upgoing), the ST segment will be negative (or depressed).

PV Card: Sgarbossa’s Criteria

In 1996, Sgarbossa et al looked through the GUSTO-1 trial patients with LBBB and AMI. They derived 3 criteria which may help diagnose the “hidden” AMI. The criteria are:

1. ST elevation ≥ 1 mm concordant with QRS complex (most predictive of AMI of the 3 criteria)
2. ST depression ≥ 1 mm in lead V1, V2, or V3
3. ST elevation ≥ 5 mm where discordant with QRS complex

Use these criteria with caution though. None of these criteria are perfect. They are to help you risk-stratify. For instance, criteria #3 (ST elevation ≥ 5 mm) can exist in asymptomatic patients with LBBB because of concurrent left ventricular hypertrophy and high voltages.

Thanks to Tom Bouthillet at for the useful illustration above.
Go to ALiEM (PV) Cards for more resources.
By |2021-10-17T09:25:38-07:00Nov 5, 2010|ALiEM Cards, Cardiovascular, ECG|
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