Posts tagged “RBBB

In re Littmann et al. (2007)…

For background regarding EKG double counting and Littmann’s sign of  hyperkalemia, see March, 2012.

The following was recorded from an 82 year-old female with lethargy and malaise; electrolyte status is unknown, as is any further clinical data.

This is a 10 second strip with 9 QRS complexes; the true heart rate is thus 54bpm. The GE-Marquette 12SL interpretation algorithm has counted 163bpm, (3 x 54 = 162). Assuming that this is a result of systematic error and not coincidence, both the mechanism and significance of triple counting remain unclear.

Case No. 3: Status Post Cardiac Arrest

An 84yr old white female, s/p VT/PEA arrest.

This ECG demonstrates AV dual sequenced pacing with loss of atrial capture. Note the high left axis in the x-y plane, consistent with typical pacer findings, but an atypical rightward shift of electrical forces across the precordial z-axis (inverse R-wave progression). Traditionally ventricular pacing electrodes are deployed in the right heart and result in a LBBB ECG morphology as the myocardial tissue depolarizes from right to left. Yet in this case we see a dramatic RBBB pattern, raising concerns about displacement or septal perforation, particularly given that the pt. has received CPR. The etiology of RBBB pacer morphology is not exclusively pathological, however, and receives a good discussion on Dr. S. Venkatesan’s Cardiology Blog. Note that the QRS in this case is elongated above 160ms, and necessarily reflects slow and poorly coordinated ventricular contraction, perhaps betraying a newly aberrant interventricular conduction pathway, even for this 100% paced patient.

Another interesting example of a similar RBBB effect can be seen at Dr. M. Rosengarten’s electrocardiography site, and there is a thorough case report and research analysis of the phenomenon in The Journal of Electrocardiography Vol.6 No. 1, 2003.

Shortly after this 12-lead was captured, the pt. again deteriorated into PEA and was lost to resuscitative efforts.