Pathophysiology of Atrial Flutter

atrial flutter is:

1)  a rapid heart beat with a regular rhthm
2) causes include corrective surgery for congenital heart disease, mitral valve disease, and cardiomyopathy

Type 1 atrial flutter (classic)

3) electrical pathway goes through the subeustachian isthmus with flutter traveling in a counterclockwise manner (rate usually 280-320 atrial beats per minute

Type 2 atrial flutter

4) faster rate (340-350 atrial beats per minute)

Characteristic Test Findings

ECG – Type 1 atrial flutter has a sawtooth pattern in inferior leads (II, III, and aVF) and V1 has discrete flutter waves

Associated Conditions

1) corrective surgery for atrial septal defects, tetralogy of Fallot, and great vessel transposition
2) thyrotoxicosis
3) pulmonary embolus
4) mitral stenosis
5) pericarditis
6) acute respiratory failure
7) atrial fibrillation
8) sinoatrial node dysfunction

Inheritance and Epidemiology

atrial flutter can occasionally occur in normal individual but most common in children and adults who have undergone corrective surgery

Treatment

Clinically stable patient

1) give digitalis to slow ventricular rate before giving a class IA antiarrhythmic (e.g., quinidine)
2) calcium channel blockers (e.g., verapamil or diltiazem)

Clinically unstable patient (or if in 1:3 or 1:4 block)

3) should cardiovert starting at 50 J
4) rapid atrial pacing with concomitant use of beta blockers
5) ibutilide (must watch closely for conversion to torsades de pointes
6) amioadarone
7) radiofrequency ablation if condition is chronic
8) anticoagulation – use only if condition is of long-term duration and refractory to treatment

Tips for USMLE

1) responding ventricular rate is usually expressed as ratio of atrial rate (e.g., 2:1, which means the ventricles are beating at 150 bpm); thus a narrow QRS at 150 bpm is likely to be atrial flutter
2) carotid sinus massage does not interrupt atrial flutter but will cause a temporary AV block and will transiently drop the heart rate from 150 to 75 bpm (this parasympathetic stimulus drops ventricular rate and increased atrial rate); thus carotid massage can be used to help make diagnosis
3) if ECG shows “sawtooth” tracing think atrial flutter
4) atrial flutter is rapid rate, regular rhythm; atrial fibrillation is rapid rate, irregular rhythm