Atrial Flutter Workup

Updated: Dec 30, 2015
  • Author: Lawrence Rosenthal, MD, PhD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
  • Print
Workup

Approach Considerations

Electrocardiography (ECG) is essential in making the diagnosis. Transthoracic echocardiography (TTE) is the preferred modality for evaluating atrial flutter.

The history and physical examination findings guide laboratory studies. Although hyperthyroidism is a rare cause of atrial flutter, asymptomatic hyperthyroidism, especially in elderly patients, can manifest as atrial fibrillation or flutter and should be excluded with thyroid function studies.

Obtain a complete blood count (CBC) if anemia is suspected or the patient has a history of recent or current blood loss associated with presenting symptoms. Serum electrolytes and pulmonary function tests may be indicated based on the history. Obtain serum electrolyte and digoxin levels if appropriate. Consider obtaining blood gas measurements in patients with hypoxia or carbon monoxide intoxication.

Chest radiography may be useful in evaluation of lung disease and the pulmonary vasculature. Chest radiographic findings are usually normal in patients with atrial flutter, but radiographic evidence of pulmonary edema may be present in subacute cases.

Next:

Electrocardiography

In the common form of type I atrial flutter, the ECG shows sawtooth flutter (F) waves. Flutter waves are often visualized best in leads II, III, aVF, or V1 (see the image below). The flutter waves for typical (type I) atrial flutter are inverted (negative) in these leads because of a counterclockwise reentrant pathway. Sometimes, they are upright (positive) when the reentrant loop is clockwise. Flutter waves (particularly 2:1) can deform the ST complex in such a manner as to mimic an ischemic injury pattern on the 12-lead ECG.

12-Lead ECG of type I atrial flutter. Note negativ 12-Lead ECG of type I atrial flutter. Note negative sawtooth pattern of flutter waves in leads II, III, and aVF.

In typical (ie, type I) atrial flutter, the atrial rate is usually 250-350 beats/min. The ventricular response may be regular or irregular. In patients with typical atrial flutter, class IA and IC antiarrhythmic drugs and amiodarone can reduce the rate to approximately 200 beats/min. If this occurs, the ventricles can respond in a 1:1 fashion to the slower atrial rate. The rate in atypical (ie, type II) flutter is 350-450 beats/min.

The ventricular rate reflects a fixed mathematical relation between flutter waves and the resulting QRS complexes. Variable atrioventricular (AV) conduction can also be seen; patients commonly present with 2:1 or 3:1 AV conduction. With 1:1 AV conduction, hemodynamic collapse may occur. Deterioration to 1:1 conduction can occur in patients with healthy hearts but is a particular risk in patients with a preexcitation syndrome (Wolff-Parkinson-White). An ECG clue to a preexcitation syndrome is a very short PR interval (< 0.115 s) and no delta wave.

The morphology of the flutter wave can predict findings in the electrophysiology laboratory. A negative flutter wave in the inferior limb leads and a positive flutter wave in V1 are highly predictive of a counterclockwise circuit; however, with positive flutter waves in the inferior limb leads and negative flutter waves in V1, differentiating between clockwise type I atrial flutter and atypical forms of non–isthmus-dependent intra-atrial reentry is difficult.

Flutter and fibrillation often coexist in the same ECG tracing. Alternating patterns (eg, fib-flutter and flitter) may be seen.

Previous
Next:

Diagnostic Aids

Vagal maneuvers can be helpful in determining the underlying atrial rhythm if flutter waves are not seen well. Adenosine, administered in an intravenous (IV) push followed with an IV bolus with flush, can also be helpful in making the diagnosis of atrial flutter by transiently blocking the AV node (see the image below). Approximately 15% of atrial tachycardias will also terminate with adenosine.

Type I atrial flutter unmasked by adenosine (Adeno Type I atrial flutter unmasked by adenosine (Adenocard).

Exercise testing can be utilized to identify exercise-induced atrial fibrillation and to evaluate ischemic heart disease. A Holter monitor can be used to help identify arrhythmias in patients with nonspecific symptoms, to identify triggers, and to detect associated atrial arrhythmias.

Previous
Next:

Echocardiography

TTE is the preferred modality for evaluating atrial flutter. It can evaluate right and left atrial size, as well as the size and function of the right and left ventricles, thereby facilitating diagnosis of valvular heart disease, left ventricular hypertrophy (LVH), and pericardial disease.

TTE has low sensitivity for intra-atrial thrombi. Transesophageal echocardiography (TEE) is the preferred technique for detecting thrombus in the left atrium.

Previous