Atrial FlutterAtrial Flutter

Chris CaulfieldChris Caulfield

AM ReportAM Report

2/19/102/19/10

DefinitionDefinition

Atrial Flutter is rapid, regular atrial Atrial Flutter is rapid, regular atrial depolarizations at a characteristic depolarizations at a characteristic rate of approximately 300 beats/min.rate of approximately 300 beats/min.

Prolonged atrial flutter can ultimately Prolonged atrial flutter can ultimately impair cardiac output, increase impair cardiac output, increase myocardial oxygen demand, and myocardial oxygen demand, and cause atrial thrombus formation.cause atrial thrombus formation.

EpidemiologyEpidemiology

In one study, estimated that the incidence of in In one study, estimated that the incidence of in the United States is about 200,000 new cases the United States is about 200,000 new cases per year, and occurs more common in men and per year, and occurs more common in men and in older adults.in older adults.

Risk of developing atrial flutter increased 3.5 Risk of developing atrial flutter increased 3.5 times in patients with heart failure and 1.9 times in patients with heart failure and 1.9 times in those with chronic obstructive lung times in those with chronic obstructive lung diseasedisease

Unusual to occur in a normal heart, and is Unusual to occur in a normal heart, and is especially uncommon in children and young especially uncommon in children and young adultsadults

Classification of TypeClassification of Type

Type I is considered typical and has Type I is considered typical and has an atrial rate 240 to 340 beats/min an atrial rate 240 to 340 beats/min

Type II is considered atypical and has Type II is considered atypical and has an atrial rate of 340 to 440 beats/min an atrial rate of 340 to 440 beats/min

Type I Atrial FlutterType I Atrial Flutter

Typical atrial flutter, or "isthmus-Typical atrial flutter, or "isthmus-dependent" flutter, is a macroreentrant dependent" flutter, is a macroreentrant arrhythmia that involves a long slow path arrhythmia that involves a long slow path with an excitable gap, forming a circuit with an excitable gap, forming a circuit within the right atrium.within the right atrium.

Slowly conducting reentrant circuit is Slowly conducting reentrant circuit is located in the low right atrial isthmus.located in the low right atrial isthmus.

The isthmus of tissue is between the The isthmus of tissue is between the inferior vena cava and tricuspid annulus.inferior vena cava and tricuspid annulus.

Type IType I

Type I Type I

Type II Atrial FlutterType II Atrial Flutter

Atypical atrial flutter lacks an excitable gap Atypical atrial flutter lacks an excitable gap and is not isthmus-dependent.and is not isthmus-dependent.

Usually this rhythm results from an intra-Usually this rhythm results from an intra-atrial reentrant circuit that is very short.atrial reentrant circuit that is very short.

May be due abnormal anatomy within the May be due abnormal anatomy within the right or left atrium (i.e. surgical scars, right or left atrium (i.e. surgical scars, irregular pulmonary veins, disturbed mitral irregular pulmonary veins, disturbed mitral annulus)annulus)

SymptomsSymptoms

PalpitationsPalpitations FatigueFatigue LightheadednessLightheadedness Shortness of breathShortness of breath

Less common symptoms include Less common symptoms include angina, hypotension, or syncope angina, hypotension, or syncope

Diagnosis: EKGDiagnosis: EKG

EKG will typically show 2:1 conduction across EKG will typically show 2:1 conduction across the AV node (even ratios of conduction are the AV node (even ratios of conduction are more common than odd ratios) more common than odd ratios) 1:1 conductive response suggests catecholamine 1:1 conductive response suggests catecholamine

excess, parasympathetic withdrawal, or the excess, parasympathetic withdrawal, or the existence of an accessory bypass tract in pre-existence of an accessory bypass tract in pre-excitationexcitation

May need to administer adenosine to slow May need to administer adenosine to slow conduction through AV nodeconduction through AV node

Diagnosis: EKGDiagnosis: EKG

Diagnosis: EKGDiagnosis: EKG

Diagnosis: Underlying Diagnosis: Underlying CausesCauses

Rheumatic heart Rheumatic heart disease (if MV disease (if MV involved)involved)

LV LV dysfunction/heart dysfunction/heart failurefailure

Sick sinus Sick sinus syndromesyndrome

PericarditisPericarditis

Pulmonary Pulmonary embolismembolism

Chronic obstructive Chronic obstructive pulmonary diseasepulmonary disease

Mitral valve Mitral valve prolapseprolapse

HyperthyroidismHyperthyroidism Status post CABGStatus post CABG

Uncommon complication of acute MI and digitalis Uncommon complication of acute MI and digitalis toxicitytoxicity

Further DiagnosisFurther Diagnosis

Serum electrolytes, pulmonary and thyroid Serum electrolytes, pulmonary and thyroid function tests should be ordered if appropriate.function tests should be ordered if appropriate.

Transthoracic echocardiography should be Transthoracic echocardiography should be performed to evaluate for structural and valvular performed to evaluate for structural and valvular abnormalities along with LV systolic function.abnormalities along with LV systolic function.

Holter monitoring or event recorders could be Holter monitoring or event recorders could be provided in an ambulatory setting if symptoms are provided in an ambulatory setting if symptoms are non-specific and an arrhythmia is considered but non-specific and an arrhythmia is considered but has not been detected.has not been detected.

Electrophysiological studies may be required at a Electrophysiological studies may be required at a later point for further diagnosis and therapy.later point for further diagnosis and therapy.

TreatmentTreatment

Control of ventricular rateControl of ventricular rate

Reversion to NSRReversion to NSR

Maintenance of NSRMaintenance of NSR

Prevention of systemic embolizationPrevention of systemic embolization

Control of ventricular rateControl of ventricular rate Intravenous calcium channel blockers Intravenous calcium channel blockers

(Diltiazem or Verapamil) or beta blockers (Diltiazem or Verapamil) or beta blockers (Esmolol) may be used to control rapid (Esmolol) may be used to control rapid ventricular rate. ventricular rate.

Digoxin is not typically used except Digoxin is not typically used except occasionally in patients with heart failure.occasionally in patients with heart failure.

Amiodarone can also be used for control of Amiodarone can also be used for control of rapid ventricular response, but could rapid ventricular response, but could promote conversion to sinus rhythm, promote conversion to sinus rhythm, increasing risk of embolization if not increasing risk of embolization if not anticoagulated.anticoagulated.

Reversion to NSRReversion to NSR

The optimal outcome of atrial flutter is reversion to and The optimal outcome of atrial flutter is reversion to and maintenance of normal sinus rhythm, not ventricular rate maintenance of normal sinus rhythm, not ventricular rate control.control. Cardioversion can be performed by electrical or chemical means.Cardioversion can be performed by electrical or chemical means.

DC cardioversion is the choice for reversion to sinus rhythm if DC cardioversion is the choice for reversion to sinus rhythm if the patient is hemodynamically unstable and is the patient is hemodynamically unstable and is uninstrumented. (starting at 50 to 100 J with biphasic uninstrumented. (starting at 50 to 100 J with biphasic defibrillators)defibrillators)

Stable patients may convert after watchful waiting.Stable patients may convert after watchful waiting.

Factors that predict spontaneous reversion to sinus rhythm or Factors that predict spontaneous reversion to sinus rhythm or a successful cardioversion include:a successful cardioversion include: Left atrial size less than 4.5 to 5 cmLeft atrial size less than 4.5 to 5 cm Atrial flutter of recent onset with little or no heart failureAtrial flutter of recent onset with little or no heart failure No underlying reversible cause (i.e. hyperthyroidism)No underlying reversible cause (i.e. hyperthyroidism)

Chemical CardioversionChemical Cardioversion

Anti-arrhythmic agents that can be used for cardioversion Anti-arrhythmic agents that can be used for cardioversion include flecainide, dofetilide, propafenone, ibutilide, and include flecainide, dofetilide, propafenone, ibutilide, and amiodarone.amiodarone.

Flecainide is contraindicated in CAD, structural heart Flecainide is contraindicated in CAD, structural heart disease, and LVH (as per CAST)disease, and LVH (as per CAST) LV hypertrophy without ischemia or conduction delay, class III LV hypertrophy without ischemia or conduction delay, class III

agents, specifically amiodarone, can be used.agents, specifically amiodarone, can be used. Ischemic heart disease, sotalol or amiodarone can be used. Ischemic heart disease, sotalol or amiodarone can be used.

(Avoid class IC agents)(Avoid class IC agents) Significant systolic dysfunction, amiodarone and dofetilide can Significant systolic dysfunction, amiodarone and dofetilide can

be used. (Avoid class IC agents)be used. (Avoid class IC agents)

Slowing of the atrial flutter rate with anti-arrhythmics alone Slowing of the atrial flutter rate with anti-arrhythmics alone can lead to 1:1 conduction.can lead to 1:1 conduction. Class IA and IC drugs should be administered in conjunction Class IA and IC drugs should be administered in conjunction

with an AV nodal blocking agent (beta blocker or calcium with an AV nodal blocking agent (beta blocker or calcium channel blocker)channel blocker)

AnticoagulationAnticoagulation

It is unusual to have thrombus form in the left atrial It is unusual to have thrombus form in the left atrial appendage because of the regularity of atrial contractions in appendage because of the regularity of atrial contractions in atrial flutter.atrial flutter. However, atrial fibrillation can be a rhythm underlying atrial However, atrial fibrillation can be a rhythm underlying atrial

flutter.flutter.

As in Afib, if atrial flutter persists for more than 48 hours, 4 As in Afib, if atrial flutter persists for more than 48 hours, 4 weeks of adequate anticoagulation or TEE is needed before weeks of adequate anticoagulation or TEE is needed before attempting cardioversion to sinus rhythm.attempting cardioversion to sinus rhythm.

If TEE does not visualize the presence of left atrial thrombus, If TEE does not visualize the presence of left atrial thrombus, cardioversion can be performed with continuation of cardioversion can be performed with continuation of warfarin for four weeks after cardioversion. However, the warfarin for four weeks after cardioversion. However, the safety of this approach has not been formally studied in safety of this approach has not been formally studied in atrial flutter.atrial flutter.

Among patients with atrial fibrillation and flutter, the choice Among patients with atrial fibrillation and flutter, the choice between warfarin and aspirin is based upon the estimated between warfarin and aspirin is based upon the estimated stroke risk using the CHADS2 score.stroke risk using the CHADS2 score.

AblationAblation Radiofrequency ablation interrupts the reentrant circuit in Radiofrequency ablation interrupts the reentrant circuit in

order to prevent the recurrence of atrial flutter.order to prevent the recurrence of atrial flutter.

With recurrent symptomatic Type I atrial flutter, there is a With recurrent symptomatic Type I atrial flutter, there is a success rate of higher than 95% with ablation.success rate of higher than 95% with ablation. Ablation is commonly performed at the 6:00 position on the Ablation is commonly performed at the 6:00 position on the

tricuspid valve isthmus.tricuspid valve isthmus.

Type II atrial flutter is also amenable to ablation and success Type II atrial flutter is also amenable to ablation and success rate is close to 95%, but recurrence is more common than Type rate is close to 95%, but recurrence is more common than Type I. I.

In patients with atrial flutter treated with ablation who In patients with atrial flutter treated with ablation who subsequently develop a fib (56% in one study), ablation of the subsequently develop a fib (56% in one study), ablation of the AV junction may need to be performed with placement of AV junction may need to be performed with placement of pacemaker.pacemaker.

Take Home PointsTake Home Points

Typical atrial flutter (Type I) is an “isthmus-Typical atrial flutter (Type I) is an “isthmus-dependent” flutter involving a dependent” flutter involving a macroreentrant arrhythmia down a long slow macroreentrant arrhythmia down a long slow path, due to an isthmus of tissue between the path, due to an isthmus of tissue between the IVC and tricuspid annulus.IVC and tricuspid annulus.

Atypical atrial flutter (Type II) is not isthmus-Atypical atrial flutter (Type II) is not isthmus-dependent and involves an intra-atrial dependent and involves an intra-atrial reentrant circuit that is very short and related reentrant circuit that is very short and related to abnormal anatomy within the right or left to abnormal anatomy within the right or left atrium.atrium.

Take Home PointsTake Home Points

IV calcium channel blockers (Diltiazem or Verapamil) or IV calcium channel blockers (Diltiazem or Verapamil) or beta blockers (Esmolol) may be used to control rapid beta blockers (Esmolol) may be used to control rapid ventricular rate.ventricular rate.

The optimal outcome of atrial flutter is reversion to and The optimal outcome of atrial flutter is reversion to and maintenance of normal sinus rhythm, not ventricular rate maintenance of normal sinus rhythm, not ventricular rate control.control.

Cardioversion can be performed by electrical or chemical Cardioversion can be performed by electrical or chemical means.means.

If TEE does not visualize the presence of left atrial If TEE does not visualize the presence of left atrial thrombus, cardioversion can be performed with thrombus, cardioversion can be performed with continuation of warfarin for four weeks after cardioversion.continuation of warfarin for four weeks after cardioversion.

Radiofrequency ablation should be considered prior to Radiofrequency ablation should be considered prior to starting an antiarrhythmic agent. starting an antiarrhythmic agent.