TOC | Cardiology    ATRIAL FLUTTER
Atrial flutter is a supraventricular tachycardia frequently found in association with atrial fibrillation. It is, however, an entity distinct from atrial fibrillation. Atrial flutter is the result of macro reentry involving the entire atrium in the circuit.

Etiologies:

• Atherosclerotic heart disease • MI • Thyrotoxicosis • COPD • Pulmonary embolism • Mitral valve disease • Cardiac surgery •

 Sx & Dx:    (REF: Cheng-Zaas: The Osler Medical Handbook, 1st ed. 2003)
Atrial flutter often has the same symptoms as atrial fibrillation. The atrial rate is typically between 250 and 350 beats/min, with resultant 2:1 or 4:1 atrioventricular conduction block. Diagnosis is based on the 12-lead ECG. The blocked flutter waves may not be readily apparent on 12-lead ECG because they may be masked by the QRS complex. The presence of a regular, narrow complex tachycardia at 150 beats/min should raise suspicion for the presence of atrial flutter and prompt a close comparison of the ECG with a prior sinus rhythm ECG to look for blocked flutter waves.

• Acute management of atrial flutter does not differ significantly from that of atrial fibrillation.
Patients with hemodynamic compromise should undergo emergency cardioversion. Stable patients can be treated acutely with ß-blockers or calcium channel blockers for rate control.

• Atrial flutter can be cured with radiofrequency catheter ablation.

Non-pharmacologic Therapy

1. Valsalva maneuver or carotid sinus massage usually slows the ventricular rate (increases grade of AV block) and may make flutter waves more evident.
2. For unstable atrial flutter patient:  
   Electrical DC synchronized cardioversion is given at low energy levels (20 to 25 J, up to 100 joules under mild sedation).
3. Atrial pacing at rates of 115-130% of the atrial flutter rate can usually convert the atrial flutter to sinus rhythm.

Acute Pharmacologic Rx for hemodynamically stable atrial flutter patient:

IV diltiazem or digoxin Rx  (start 0.5-1mg IV) may be tried to slow the ventricular rate and convert flutter to fibrillation.

• Cardizem (Diltiazem) IV bolus for rate control of atrial fib/flutter.
  - * Start 0.25 mg/kg IVP over 2 min (ave pt= 20mg dose), after 15 min if inadequate response, 0.35 mg/kg (ave pt = 25 mg dose) over 2 min;
        Infusion Rx start at 5 mg/h, range 10 - 15 mg/h.
  Verapamil  (Calan) 5-10 mg IV (0.075 - 0.15 mg/kg)
  - * Calcium blockers are contraindicated in atrial fib assoc. with  WPW Syndrome.
• Digoxin 0.5-1 mg IV initial loading dose, then about 0.25 mg maintenance dose
• Adenosin 6-12 mg IV bolus
• Atenolol (Tenormin) 5 mg IV, may repeat in 10 min  
  Metoprolol (Lopressor) 2.5-5 mg IV, may repeat q2-5 min up to 15 mg  over 10-15 min
  Propranolol 1-3 mg IV, start with 1 mg, then repeat with increment of 1 mg q5min
  Esmolol IV 50-100 ug/kg/min for 4 min, then maintain at 50 ug/kg/min. (Max IV infusion rate 200 mcg/kg/min)

• Atrial flutter is frequently associated with intermittent atrial fibrillation.  
It may be prudent to anticoagulate patients with atrial flutter and coexisting medical disorders (e.g., diabetes mellitus, hypertension, cardiac disease) before cardioversion. Anticoagulation should also be considered for all patients with atrial flutter who are older than 65 years of age.

Rx of Chronic Atrial Flutter (often quite refractory to pharmacologic Rx & tends to recur shortly after an electrical cardioversion)

• Chronic atrial flutter may respond to amiodarone.
• Radiofrequency ablation to interrupt the atrial flutter is also effective for patients with chronic or recurring atrial flutter.
• Rate control with digoxin, Beta-blockers, or Calcium antagonists.

For patients with recurrent, symptomatic atrial flutter, first-line therapy should be ablation rather than antiarrhythmic drug therapy. In a randomized study 61 patients with atrial flutter were assigned to primary treatment with catheter ablation or antiarrhythmic drug (AAD) therapy. At the end of 1 year, atrial flutter had recurred in 6% of the ablation group and 93% of the AAD group; atrial fibrillation occurred in 29% of the ablation group and 60% of the AAD group. Hospitalizations were also less frequent in the patients treated primarily with ablation (22% versus 63%).

12132004