Wednesday, October 26, 2016

RSR' with ST elevation: is this Right Bundle Branch Block with STEMI? Type 2 Brugada?

A very healthy 40 year-old man went to his primary care physician for a check-up. He denied any chest pain, dyspnea, or exertional intolerance, but an ECG was obtained:
The ECG is fairly normal with the exception of the rSr’ pattern and ST segment elevation in V1 and V2. The QRS duration is 108 milliseconds, consistent with incomplete right bundle branch block (RBBB).  The ST elevation in V1 is less than 2 mm, and so does not meet criteria for type 1 Brugada.
The "saddleback"
 in V2 suggests RBBB with STEMI, although very unlikely (see 2 cases below).
Type 2 Brugada might also be considered, but
the beta-angle is far too acute

Notice the P-wave in V1 is all negative.
As you can see, the computer warned of possible STEMI

See these 2 posts:

ST elevation (Saddleback), is it STEMI?

Is this Saddleback a STEMI??

Of course, he was sent by ambulance to the ED for this possible STEMI.

The ECG was immediately repeated in the ED: 
The rSr’ pattern is not seen in V1, but it is seen in V2, with ST elevation. Such ST elevation in the presence of RBBB, or incomplete RBBB, might strongly suggest RBBB with STEMI. 
However, a saddleback STE in V2 is rarely due to STEMI. 
The P-wave in V1 is mostly negative.
What is going on?

After review by a physician, the cath lab was not activated.

The patient’s history was not suggestive of either ischemia or occult Brugada, and the physical exam demonstrated only an athletic physique.

The ED physician suspected upwards misplacement of V1 and V2 as the cause of the ECG findings. Such misplacement is very common - Wenger and Kligfield found that > 40% of V1 and V2 placements were too high.

Upwards misplacement of V1 and V2 can generate false Q waves, poor R wave progression, and ischemic patterns. Such misplacements can also easily produce psuedo-Brugada patterns, especially in athletic males.

There are certain clues to this upwards misplacement of V1 and V2. Garcia-Niebla analyzed 101 normal subjects, and found that the P waves provided most of the evidence.

Reexamine the first ECG:
The P is wholly negative in V1, and V1 also has a rSr’ morphology. This only happened when V1 and V2 were placed in the second intercostal space, almost at the clavicles!

The ED physician asked for the ECG to be repeated, and placed the precordial leads himself.
(Written consent obtained from patient)
With proper lead placement, the ECG was repeated:
This last ECG shows a normally biphasic P in V1, and an upright P in V2, confirming proper position. The rSr’/IRBBB pattern has disappeared, along with the saddle-back complex. Some STE remains, but is normal variant STE (early repolarization).

Learning Point:

1.  Lead misplacement can result in abnormalities that simulate pathology.
2.  RSR' in lead V1 is particularly common and due to high lead placement of leads V1 and V2
3.  Saddleback in V2 is also common
4. Analysis of the P-wave morphology greatly aids in assessing good lead placement

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