Atrial flutter is a regular and monomorphic atrial arrhythmia, with a atrial rate of 250-350 beats / minute and regular or irregular ventricular activity, in relation to the variability and the degree of atrioventricular block. Ventricular rhythm is usually regular, with a frequency of 150 beats / minute, corresponding to a heart block 2 / 1.
Atrial flutter may be paroxysmal, or rarely, permanent, and if the arrhythmia persists for more than a week, there is a tendency to pass into atrial fibrillation.
Atrial flutter, appears in the following situations:
- In heart disease: myocardial infarction, coronary artery disease, mitral stenosis, aortic stenosis, mitral regurgitation, aortic regurgitation, hypertrophic cardiomyopathy, dilated cardiomyopathy, hypertensive cardiomyopathy, myocarditis, pericarditis, chronic pulmonary heart disease;
- Other medical conditions: hypoxia and hypercapnia, in chronic hyperthyroidism, electrolyte disturbances, hypotension, cardiogenic shock, acute alcoholism, coffee and tobacco abuse and stress.
Diagnosis of atrial flutter:
The diagnosis of atrial flutter is based on the symptoms, on the physical examination and on the ECG interpretation.
Symptoms. Severity of symptoms depends on the ventricular rate and heart condition. May be present: palpitations, dizziness, anxiety, faintness, shortness of breath, attacks of angina pectoris (especially in form with atrioventricular block 2 / 1) especially if it is a severe cardiomyopathy. Atrial flutter with ventricular rate of 75 beats / minute may be asymptomatic.
Physical examination may reveal the following aspects:
- Heart sounds are usually tachycardic and regular, but sometimes may be irregular, when exist a variable atrioventricular block.
- Effort can double the ventricular rate ( from 75 beats / minute increase to 150 beats / minute or from 150 beats / minute increase to 300 beats / minute), or can have no effect.
- Vagal stimulation maneuvers produce an increasing in atrioventricular block with ventricular rate which will be temporarily decreased, which will return to the baseline value after the cessation of the maneuver.
ECG examination shows the following:
- The absence of P waves, the P waves are replaced by “F” waves of flutter, between which are no isoelectric intervals.
- F waves have a frequency of 250-350 beats / minute, are monomorphic, regular and have the appearance of “saw tooth”.
- QRS complex has a normal aspect, it may have a longer duration than usual, if there is a branch block or a ventricular preexcitation syndrome.
- In the absence of atrioventricular accessory pathways, driving trough ventricles is the most common, with block 2 / 1 ( can be met atrioventricular block 3 / 1 or 4 / 1). Atrioventricular driving 1 / 1, although rare, is possible and occurs when the atrial rate is lower (about 200 beats / minute), in ventricular preexcitation syndromes, in hopertiroidism and in children.
- When driving is variable, QRS complexes occur at irregular intervals, and F waves are well evidenced in the ECG.
Treatment of atrial flutter:
Treatment of atrial flutter consists of: electrical conversion, rapid atrial electrostimulation (overdriving) or pharmacological conversion.
- Electrical conversion is currently recommended in forms of atrial flutter with hemodynamic deterioration or in combination with Wolf-Parkinson-White syndrome. After sedation, is applied an external electric shock, synchronous with low energy (20-50 joules), which can be repeated if necessary. Anticoagulant therapy should be considered in case of atrial flutter with a length greater than 48 hours.
- Rapid atrial electric stimulation (overdriving) shall be done in atrial flutter occurred after open heart surgery or after the onset of a myocardial infarction, especially in patients who are treated with digoxin.
- Pharmacological treatment is aimed at patients with atrial flutter who are hemodynamically stable:
- First will be tempt the decrease of ventricular rate with atrioventricular blockers: verapamil, diltiazem, digoxin, esmolol. Sometimes digoxin can converse a atrial flutter into a atrial fibrillation.
- Pharmacological conversion of atrial flutter is done with antiarrhythmic from class I and class III, in particular: flecainide, propafenone, sotalol, amiodarone, dofetilide, ibutilide, which are intravenously administered. They will be used, only if the treatment to decrease ventricular rate was effective because the decrease only of the atrial rate with antiarrhythmics from class I and class III will induce the appearance of atrioventricular block.
- For prevention of recurrence of atrial flutter, are used antiarrhythmics from class IA, class IC and class III, but with limited effectiveness. Failure of atrial flutter recurrence prevention requires the radiofrequency current ablation.