Tracings Vol 3.1 Answer

HPI

A 15 y.o. girl was transported by EMS to the ED. She had just experienced her second syncopal episode in 8 days. This morning while in the bathroom at her family’s home getting ready for school, she felt nauseous and then passed out. When she awoke, EMS was on the scene. She had had a previous syncopal episode 8 days prior while at school. On that occasion she had gone into the girls’ bathroom and then woke up lying on the floor. “Possible” seizure activity was observed. Since that time she has had a throbbing headache involving the entire head. Neither episode had associated chest pain, shortness of breath, faintness or focal neurologic symptoms. Her last menstrual period had been 3 weeks prior.

Past medical history was significant for a congenital single kidney and appendectomy. She was taking no medications. There was no history of drug, alcohol or tobacco use.

Physical Exam

On exam the patient appeared alert and generally well. BP was 116/66, pulse 73, respirations 20, and temperature 36.5C. General, cardiopulmonary, neurologic and extremity exams were all normal. Pulse oximetry registered a 100% saturation on room air.

Review of the EMR revealed that a brain CT performed during the ED visit 8 days prior had been normal. UDS and SDS had both been negative. The patient had been discharged from the ED and referred to her primary care physician. He had obtained a neurology consult which found no abnormalities and an EEG which was normal.

During the present visit, a 12-lead ECG was normal and initial laboratory evaluation was unremarkable. After conferring with the patient’s physician, a decision was made to obtain an echocardiogram.

While the patient was awaiting this study, the cardiac monitor alarm activated and a rhythm strip was recorded. The patient remained asymptomatic and the abnormality which had triggered the alarm resolved before any action could be contemplated.

Repeat VS and a directed exam were unremarkable.

Questions

1.  What rhythm does this strip reflect?

2.  What should be done next?

Case ECG ACase ECG B

Discussion

The rhythm strip reveals what appears to be a wide-complex QRS rhythm with a rate of around 215 bpm. On the surface this seems highly suspicious for ventricular tachycardia. Another possibility might be a supraventricular re-entrant or atrial tachycardia with aberrant conduction.

However, there are narrow QRS complexes running through and apparently dissociated from the wide-complex QRS rhythm (see arrows) and at a rate that is identical to the sinus rhythm at the beginning of the strip.

What’s going on?

Since you can’t have simultaneous and concurrent ventricular depolarizations of the ventricle triggered by both the sinus impulse and an ectopic ventciular pacemaker (note that some of the narrow beats land on the wider deflections and some land in between), the only explanation is that  the wide-complex QRS rhythm is artifact, most likely electrical in origin.

In this case, a consulting cardiologist determined that the rhythm was artifact. Further workup failed to reveal a cause for this patient’s recurrent syncope.

Lesson: look for this phenomenon when apparent wide complex rhythms are recorded by cardiac monitors, especially when the patient remains asymptomatic (although a patient can certainly remain asymptomatic during runs of VT).

Tracings is a learning module involving actual cases of patients and their ECGs that present to the Emergency Department.  Topics chosesn are dervied from the EM Model for Resident Education. Cases are prepared by Dr. William Berk.

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