This ECG shows an atrial tachycardia with atrial rate of 120bpm. The p waves are inverted in III and aVF, which is abnormal. This is a unifocal atrial tachycardia. It can occur in structurally normal and abnormal hearts. it arises from a particular part of the atrium and its location can be diagnosed by the axis of the p waves.
Below is another example:

This is someone at a rate of 120bpm. Notice the inverted p’s in lead III. Again, this is unifocal atrial tachycardia.
Clinical Presentation
The usual presentation is one of palpitations, but may be that of syncope, or cardiac failure if the patient has been in the rhythm long enough.
Workup
An ECG and electrolytes to ensure no abnormalities and a full blood count to exclude anaemia.
Very few other investigations are needed in the emergency department. Perhaps a chest xray if lung pathology is suspected. The patient should have an echocardiogram, to look for structural abnormalities, but this can be as an outpatient.
Management
The unifocal atrial tachycardia can be treated like an SVT.
The general treatment for this condition is:

1. Pharmacological
   1. Beta blockers
   2. Calcium channel blockers
2. Cardioversion

In this case we gave the patient his usual dose of Sotalol and waited, however it was clear that there was not going to be resolution, so we proceeded to cardiovert.

A 79 yo male presents with palpitations. He is haemodynamically stable with a BP of 138/68. His ECG is shown below. What does it show?

ECG: A narrow complex regular tachycardia with a ventricular rate of 145, but no visible P waves.
You think it's some type of SVT, so you try vagal manoeuvres including the new REVERSE Vagal Manoeuvre. However there is no response.
You decide to give Adenosine.
Your colleague asks "Are you sure you want to give adenosine?"
Your response is: "It's a regular narrow complex, so Adenosine should be fine. If it were irregular ie., atrial Fibrillation and there were wide complexes indicating it might be atrial fibrillation with WPW, then I wouldn't give it. We should be OK". (members go to ECG's, when giving the wrong drug can kill your patient)
​You give Adenosine and the following ECG is taken. What does it uncover?

As the ventricular beats are blocked, the p waves become evident and the underlying atrial tachycardia is uncovered. We can sometimes use the LEWIS LEAD to make p waves more prominent, however the rate may make that difficult to do here.

It is a type of supraventricular tachycardia that can occur in both normal hearts and in congenital heart disease.
The ECG usually has the following characteristics:

• Rate > 100bpm
• If seen the P waves have an atypical morphology
• There is a narrow QRS

We think of Atrial tachycardias as falling into 3 groups:

1. Focal Atrial Tachycardia
   1. It is REGULAR
   2. Localised to one atrial focus
   3. There are discrete P waves
   4. Usually caused by catecholamines/stimulants, digoxin and alcohol.
2. Multifocal Atrial Tachycardia(MAT)
   1. It is IRREGULAR because because of multiple foci firing at different times
   2. There are 3 different P wave morphologies
3. Re-Entrant Atrial Tachycardia
   1. Usually persistent
   2. Occur after cardiac surgery or ablation

MANAGEMENT

• These atrial tachycardias are usually self terminating and except for some cases of congenital heart disease are usually not life threatening.
• Focal atrial tachycardias may respond to cardioversion, however MAT DOES NOT.
• Class Ia and Ic anti-arrhythmics such as Flecainide, have some effectiveness, however we have to be sure that there are no structural abnormalities (ie., ECHO is needed) as they can be arrhythmogenic.
• Class III drugs such as Amiodarone and Sotalol, although not effective in terminating the arrhythmia are good for maintaining a sinus rhythm.
• If the patient has a re-entry atrial tachycardia, AV nodal blockers are unlikely to terminate, however cardioversion is appropriate in unstable patients.

OTHER INVESTIGATIONS
What other investigations may be appropriate?
LABS

• Electrolytes,
• Haemoglobin,
• Digoxin levels

RADIOLOGY

• CXR, looking for COPD,
• CTPA if suspicious for a PE
• ECHOCARDIOGRAPHY to look for structural heart disease, left atrial size and pulmonary arterial pressure.