CASE

A 39 year old woman presents to the Emergency Department with palpitations. She has seen her local doctor 3 days previously with the complaint of a ‘racing heart’. The local doctor has done an ECG in the practice, diagnosed atrial flutter and commenced a beta blocker ‘Metoprolol’. The patient now presents to the Emergency Department because her heart is still ‘racing’.

The patient’s recent history is that her brother had a heart attack four weeks ago. There is no past medical history, no medications and no allergies. The patient denies fevers, dyspnoea, illicit drug use and she is not on the oral contraceptive pill.

The patient’s vitals when seen are HR=112, BP 120/70, resp rate is 14, Sats are 99% on room air and she is afebrile.

DISCUSSION

The original ECG is not flutter, but in fact sinus tachycardia at a rate of 130 bpm. The computer on the ECG machine has read it as atrial fibrillation, but is incorrect. The ECG today is also sinus tachycardia.

ECG - Sinus Tachycardia

Following some investigations this patient is sent home.

Sinus tachycardia is not an uncommon presentation to the Emergency Department. It is a red flag for discharging many patients and the list of its causes is long. What do we need to look for and rule out before we can send someone home?

The definition is >100 bpm.

The possible causes of Sinus Tachycardia include:

-Sepsis and fever

-Anaemia

-Hypotension and shock

-Acute cardiac ischaemia

-Disorders causing hypoxia e.g. chronic lung disease, congestive cardiac failure

-Pulmonary embolism

-Hyperthyroidism

-Pheochromocytoma

-Stimulants or illicit drugs

In the unwell patient there are clues, but in the well patient, the rapid rule-out list is sepsis, acute coronary disease, pulmonary embolism and illicit drug use. I have had several patients who look well with persistent tachycardia and no history, who eventually tell me that they’ve had cocaine the night before.

In this patient, there was no cause found and the patient was sent home to be reviewed by the local doctor.

There are two conditions that we need to be aware of that the patient may have when all else is ruled out.

1 Postural Orthostatic Tachycardia Syndrome

This tends to occur in young women. They have a postural sinus tachycardia when upright, but no blood pressure drop. They have normal hearts.

2 Inappropriate Sinus Tachycardia

These patients have an elevated resting heart rate and may also have an exaggerated response to exercise. There may be a sinus node abnormality.

What about treatment options for these patients?

There is no real treatment if the underlying cause is not found. A trial of beta blocker may be effective. If not, radiofrequency ablation can be considered.

What if this had been atrial flutter? Was the beta blocker enough? Could this patient have been sent home? Should she have been sent home by the local doctor? More in next time’s blog.