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Atrial tachycardias

Atrial flutter

Atrial rate varies between 280-350 per minute
Most often, every second flutter beat conducts, giving a ventricular rate of 150bpm
Occasionally, every beat conducts, producing a HR of 300bpm
Regular, sawtooth-like atrial flutter waves (F waves) between QRST complexes

If they are not clearly visible, AV conduction may be transiently impaired by carotid sinus massage or by the administration of AV nodal blocking drugs (e.g. verapamil)

Treatment:

DC cardioversion (50J, 100J and then 360J)
Class III drugs are often effective (e.g, amiodarone)
AV nodal blocking drugs (class II or IV or digitalis) may be used to control the ventricular rate if the arrhythmia persists
Treatment of choice is now radiofrequency catheter ablation

Atrial fibrillation:

Common (occurs in 5-10% of patients >65 years of age)
Atrial fibrillation is continuous, rapid (400 per minute) activation of the atria by meandering wavelets

Aetiology:

Thyrotoxicosis
Alcohol toxicity
Chest infection
Raised atrial pressure
Increased atrial muscle mass
Atrial fibrosis
Inflammation/infiltration of the atrium

Symptoms and signs:

May be asymptomatic
May lead to acute cardiac decompensation
Patient has an irregularly irregular pulse that is maintained, even during exercise
The ECG shows fine oscillations of the baseline and no clear P waves
The QRS rhythm is rapid and irregular
Untreated, the ventricular rate is usually 120-180bpm

Management of atrial fibrillation:

Treat underlying cause
If this does not correct the AF, consider at least 1 go at DC cardioversion (this requires a GA or heavy sedation)
Warfarinize for 3 weeks before DC shock (100-200J) and for 4 weeks after
If DC cardioversion fails, treat as chronic AF

Chronic AF:

The aim is control of ventricular rate, not sinus rhythm
Digitalize (loading dose 0.5mg PO x 3 doses in 2 days, maintenance of 0.25mg PO OD)
If rate still to fast, check serum levels and cautiously increase the dose ± low dose ß-blockers (e.g. propranolol 10-20mg PO TDS)
Discuss the risks and benefits of anticoagulation with the patient. In general, expect to use warfarin, aiming for an INR of 2.5-3.5. However, if the patient is reluctant or the risk of emboli is small (e.g. lone AF with normal echo and no past emboli or TIA) or the risk of bleeding is high ± use of warfarin is contraindicated (e.g. on NSAIDs or past peptic ulcer) aspirin 300mg with food may be acceptable


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	Atrial tachycardias Atrial flutter Atrial rate varies between 280-350 per minute Most often, every second flutter beat conducts, giving a ventricular rate of 150bpm Occasionally, every beat conducts, producing a HR of 300bpm Regular, sawtooth-like atrial flutter waves (F waves) between QRST complexes If they are not clearly visible, AV conduction may be transiently impaired by carotid sinus massage or by the administration of AV nodal blocking drugs (e.g. verapamil) Treatment: DC cardioversion (50J, 100J and then 360J) Class III drugs are often effective (e.g, amiodarone) AV nodal blocking drugs (class II or IV or digitalis) may be used to control the ventricular rate if the arrhythmia persists Treatment of choice is now radiofrequency catheter ablation Atrial fibrillation: Common (occurs in 5-10% of patients >65 years of age) Atrial fibrillation is continuous, rapid (400 per minute) activation of the atria by meandering wavelets Aetiology: Thyrotoxicosis Alcohol toxicity Chest infection Raised atrial pressure Increased atrial muscle mass Atrial fibrosis Inflammation/infiltration of the atrium Symptoms and signs: May be asymptomatic May lead to acute cardiac decompensation Patient has an irregularly irregular pulse that is maintained, even during exercise The ECG shows fine oscillations of the baseline and no clear P waves The QRS rhythm is rapid and irregular Untreated, the ventricular rate is usually 120-180bpm Management of atrial fibrillation: Treat underlying cause If this does not correct the AF, consider at least 1 go at DC cardioversion (this requires a GA or heavy sedation) Warfarinize for 3 weeks before DC shock (100-200J) and for 4 weeks after If DC cardioversion fails, treat as chronic AF Chronic AF: The aim is control of ventricular rate, not sinus rhythm Digitalize (loading dose 0.5mg PO x 3 doses in 2 days, maintenance of 0.25mg PO OD) If rate still to fast, check serum levels and cautiously increase the dose ± low dose ß-blockers (e.g. propranolol 10-20mg PO TDS) Discuss the risks and benefits of anticoagulation with the patient. In general, expect to use warfarin, aiming for an INR of 2.5-3.5. However, if the patient is reluctant or the risk of emboli is small (e.g. lone AF with normal echo and no past emboli or TIA) or the risk of bleeding is high ± use of warfarin is contraindicated (e.g. on NSAIDs or past peptic ulcer) aspirin 300mg with food may be acceptable
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