Emergency Medical Services (EMS) Agency

Case:

Paramedics respond to a 58-year-old female presenting with intermittent palpitations. She states that she feels her heart racing and then suddenly feels faint.  Her symptoms started about 10 minutes prior to paramedic arrival.  She has a history of hypertension.

Case study

Rate:                                       varying

Rhythm:                                  narrow complex tachycardia with sinus pauses; occasional p-waves

ST Segment Elevation >1mm

In 2 or more contiguous

Leads?:                                    No

Reciprocal Changes:              N/A

This ECG and patient history are concerning for tachycardia-bradycardia syndrome associated with SA node dysfunction.  SA node dysfunction (sick-sinus syndrome) can occur for many reasons.  Most commonly there is structural degeneration of the cardiac tissue surrounding the SA node that prevents the SA node from conducting electrical signals needed to perform its pacemaking function.  Medications that inhibit nodal conduction (e.g. beta-blockers) or electrolyte abnormalities may further exacerbate the SA node’s inability to conduct an electrical signal.  One manifestation of ‘sick sinus syndrome’ is alternating tachycardia and bradycardia known as tachycardia-bradycardia syndrome.  Patients may be symptomatic or even syncopize, particularly during periods of bradycardia when there are long sinus pauses.

The patient should be placed on the cardiac monitor.  Given the patient’s changing dysrhythmia from tachycardia to bradycardia, this does not fit into a typical category for field management, so it is reasonable to discuss management with the Base. Pre-syncopal symptoms would most likely occur during sinus pauses where the patient is bradycardic and can be managed by TP-1212,  Cardiac Dysrhythmia – Bradycardia.  If the patient is symptomatic with signs of poor perfusion, atropine and transcutaneous pacing (TCP) can be attempted.  Stable patients may not require medications or TCP in the field and can be managed definitively after transport in the hospital setting.  This patient will require permanent pacemaker placement.

References

1. Semelka M, Gera J, Usman S.  Sick sinus syndrome: a review.  Am Fam Physician. 2013; 87(10): 691-6.