Palpitations in the emergency room

Palpitations in the emergency room

Learning Objectives:

1. Describe ECG criteria for atrial fibrillation.

2. Describe ECG criteria for atrial flutter.

3. Describe the treatment algorithm for atrial fib/flutter.

4. List antiarrhythmic agents to AVOID in atrial fibrillation with preexcitation (Wolff-Parkinson-White).

Notes:

1. If atrial fibrillation or atrial flutter have been present for more than 48 hours, conversion of the rhythm may cause thromboembolism. For unstable patients it may be safest to slow the rate rather than convert the rhythm.

2. Potentially dangerous proarryhthmic drug interactions can ocur with the use of multiple antiarhythmics. Use only one agent.

ECG Criteria for Atrial Fibrillation:

1. The heart rate is variable with an irregularly irregular rhythm.

2. The QRS complex is narrow.

3. P waves are not present, but fibrillatory waves may be present.

4. There is no relationship between the P waves and QRS complexes.

5. Atrial fibrillation is chaotic. The atrial muscle is depolarizing very rapidly in a disorganized fashion. There are no P waves since each depolarization involves little muscle mass, but oscillations can sometimes be seen in the baseline. Impulses are irregularly conducted to the AV node which conducts depending on its refractory state. The resulting QRS complexes are narrow with irregular R-R intervals.

6. The rhythm is atrial fibrillation if there are no P waves and the QRS's are irregularly irregular.

7. If there is abnormal conduction with wide QRS complexes and a rapid ventricular rate, atrial fibrillation can look like ventricular tachycardia. The irregular rhythm is the key to diagnosis of atrial fibrillation with abnormal conduction.

ECG Criteria for Atrial Flutter:

1. The heart rate is fast and the rhythm is usually regular.

2. The QRS complex is narrow.

3. The P waves are the sum of a positive and negative component and have a sawtooth appearance.

4. Frequently there are more flutter waves than QRS complexes so some degree of AV block can be present.

5. The impulse in atrial flutter travels around the atrium in a circular fashion. The atrial activity is regular, usually with a rate between 240 and 360 per minute. The QRS complexes may not be regular since variable AV block is often present.

6. The most common presentation of atrial flutter is an atrial rate of 300 with 2:1 block.

Treatment Algorithm for Atrial Fib/Flutter:

1. Secure airway, administer oxygen, obtain IV access.

2. Evaluate the patient:

a. Is the patient stable or unstable?

b. Is cardiac function impaired - low EF or CHF?

c. Is Wolff-Parkinson-White syndrome present?

d. Has the atrial fib/flutter been present for 48 hours?

3. If duration of atrial fib/flutter is longer than 48 hours or unknown duration, anticoagulate prior to cardioversion.

4. If unstable: Synchronized cardioversion 100 J, 200 J, 300 J, 360 J.

Notes:

a. Start at 50 J for atrial flutter.

b. May give brief trial of medications.

c. May need to resynchronize after each shock.

d. If synchronization results in too long a delay, may use unsynchronized shocks.

e. Consider administration of a sedative by anesthesia service prior to electrical cardioversion.

5. If stable and WPW is not present, use one of the following agents to control the rate:

a. Diltiazem - agent of first choice.

Initial IV load: 0.25 mg/kg over 2 min.

Maintenance infusion: 5 - 15 mg/hr.

Second load (if needed): 0.35 mg/kg over 2-5 min 15 min after initial dose.

b. Esmolol (beta-blocker).

6. If stable but heart function is impaired and WPW is not present, use amiodarone.

7. If stable but WPW is present, use:

a. DC cardioversion.

b. Amiodarone.

c. AVOID adenosine, beta blockers, calcium channel blockers, and digoxin as they can be harmful.

Meds to AVOID in Atrial Fibrillation with Preexcitation (Wolff-Parkinson-White)

AV Blocking medications:

1. Adenosine

2. Digoxin

3. Diltiazem

4. Verapamil