Presentation on theme: "Atrial Flutter: An Electrophysiologic Overview MAJID HAGHJOO, M.D DEPARTMENT OF PACEMAKER AND ELECTROPHYSIOLOGY RAJAIE CARDIOVASCULAR MEDICAL AND RESEARCH."— Presentation transcript:
Atrial Flutter: An Electrophysiologic Overview MAJID HAGHJOO, M.D DEPARTMENT OF PACEMAKER AND ELECTROPHYSIOLOGY RAJAIE CARDIOVASCULAR MEDICAL AND RESEARCH CENTER (RCMRC)
Objectives – Atrial Flutter Identify mechanisms and characteristics of atrial flutter Recognize ECG and intracardiac electrograms depicting different types of atrial flutter Discuss treatment options for atrial flutter
Outline – Atrial Flutter I.Description II.Characteristics A.Definition B.Types and features C.Mechanism D.Circuit recognition III.ECG and intracardiac recognition
Atrial Flutter Rapid and regular form of atrial tachycardia Usually paroxysmal More common in men than women (M/F: 4.7:1). Sustained by a macro-reentrant circuit. In most cases, circuit is confined to the right atrium and left atrium is passive bystander. In some types of atrial flutter, arrhythmia circuit located in left atrium. Episodes can last from seconds to years. Chronic atrial flutter usually progresses to atrial fibrillation.
Atrial Flutter A unique population in which atrial flutter occurs commonly is in patients in the first week after open heart surgery (a third of postoperative SVTs) It is also seen in association with: – chronic obstructive pulmonary disease – mitral or tricuspid valve disease – thyrotoxicosis – repair of congenital cardiac lesions in which the atria, most often the right atrium, is considerably incised, such as with the Mustard, Senning, or Fontan procedure or those with enlargement of the atria, especially right atrium.
Reentry Circuit of Common Atrial Flutter Morady F. N Engl J of Med. 1999;340:
Types and Features Flutter Type Mechanism Atrial rate Cure Typical * Counterclockwise RFA Macro-reentry Reverse typical * Clockwise RFA Macro-reentry Atypical Macro-reentry RFA * 90% of atrial flutters fall into the typical or reverse typical category.
Mechanisms of A-Flutter Typical (counterclockwise and clockwise) – A rapid and regular form of atrial tachycardia that is sustained by a macro-reentrant circuit which utilizes a cavotricuspid isthmus Atypical – Atrial reentry is independent from cavotricuspid isthmus – Mostly, reentry occur around scar tissue after surgery – In some cases, reentry occur around left atrium
Typical Flutter Mechanism: – Counterclockwise macro-reentrant circuit that utilizes a cavotricuspid isthmus to sustain circuit Induction: – Fast atrial pacing and/or the introduction of multiple premature beats near the low septum Termination: – Rapid atrial pacing faster than the flutter rate – Cardioversion – Spontaneous – Pharmacologic therapy
ECG Recognition Typical atrial flutter – Undulating atrial activity without a baseline – Atrial rate: bpm – Rhythm: Regular – Ventricular rate: Variable Dependent upon: – AV node conduction properties – Usually a 2:1, 4:1 fixed conduction ratio – Recognition: “Sawtooth” appearance on the surface ECG (negative deflections in inferior leads and positive deflection in V 1 ) 1:1 AV conduction ratio in atrial flutter may be seen in: Wolf-Parkinson-White syndrome (most common); Lown-Ganong-Levine syndrome; Exercise; Catecholamine therapy; Phenytoin therapy; Class I antiarrhythmic drug therapy
Other Methods of A-Flutter Recognition If diagnosis of atrial flutter is not clear from a standard ECG, any of a number of maneuvers can be useful: – Vagal maneuvers (CSM, Valsalva maneuver) – EGM recording by esophageal, transvenous, or epicardial electrodes – Pharmacologic agent: adenosine, esmolol, verapamil, diltiazem, or edrophonium. In the presence of wide QRS tachycardia, drug intervention to establish the diagnosis of atrial flutter is dangerous and contraindicated; DC cardioversion is indicated.
Atypical Flutter Mechanism: – Macroreentry that does not utilize cavotricuspid isthmus – Macroreentry occur mostly around surgical incision – Rare cases depends on functional barrier Induction: – Atrial pacing at faster rates than the flutter rate Termination: – Difficult with programmed pacing – Cardioversion – Pharmacologic therapy
ECG Recognition Atypical atrial flutter – Undulating atrial activity without a baseline – Atrial rate: 340 to 433 bpm – Atrial rhythm: Variable (flutter-fib) – Ventricular rate: Variable Dependent upon: – AV node conduction properties – Recognition: Very fast rate and variable cycle length on surface ECG, may progress to atrial fibrillation
Incisional Atrial Flutter Incisional atrial flutter – Atrial rate: Sometimes varies – Mechanism: Incisional macroreentry – Complication of surgery Congenital heart disease – Treatment: Ablated with good success using focused activation mapping to transect the isthmus of conductive tissue
Evaluation of Atrial Flutter
Confirmation of Flutter Circuit Confirm direction of rotation – During the EP study the direction of the flutter circuit should be confirmed – Flutter should be present before the patient enters the lab, if not, attempts should be made to induce the tachycardia – Direction can be confirmed by using a multi-pole catheter positioned around the tricuspid annulus, and pacing near the isthmus
Atypical Flutter mimicking typical flutter
Activation Sequence of Typical Atrial Flutter (LAO View)
Fluoroscopic PA and LAO views of a multipolar reference catheter
Concealed Entrainment Used to verify that isthmus is utilized by the tachycardia Pace the isthmus at a cycle length 20 to 40 msec shorter than the tachycardia cycle length No change on surface ECG No change on intracardiac recordings Tachycardia resumes its original cycle length upon termination of pacing
Treatment Options: Acute A-Flutter Pharmacologic therapy Rapid Atrial Pacing Direct Current Cardioversion
Treatment Options: Acute A-Flutter Pharmacologic therapy for rhythm control – IV ibutilide – Oral flecainide, single dose of 300 mg – Oral propafenone, single dose of 600 mg Pharmacologic therapy for rate control – IV calcium channel blockers (verapamil, diltiazem) – IV beta-blockers (esmolol)
Treatment Options: Acute A-Flutter Rapid Atrial Pacing – Method of choice in postcardiac surgery atrial flutter – Pacing should be performed from high right atrium because the appearance of positive atrial complexes in ECG lead II is the hallmark of interruption of atrial flutter Ramp pacing at a rate about 10 bpm faster than flutter rate and then gradually increased until the atrial complexes in lead II become positive Burst pacing at a rate 120% to 130% of the flutter rate and continued for 15 to 30 seconds until the atrial complexes in lead II become positive; if flutter continued, pacing rate should be increased by 5 to 10 bpm. – Recommended minimum duration of pacing is 10 seconds and stimulus strength of at least 10 mA is needed. – When esophageal pacing is used : a duration of at least 9 to 10 ms and up to 30 mA in strength is needed. Pacing should be initiated at a relatively slow rate to demonstrate that no ventricular capture is inadvertently produced.
Treatment Options: Acute A-Flutter Direct Current Cardioversion – Contraindicated in patients after having recently eaten or those with COPD – Using a standard shock, at least 50 J is generally recommended. Because 100 J is virtually always successful and virtually never harmful, it should be considered as the initial shock.
Treatment Options: Chronic A- Flutter Pharmacologic therapy – Currently class IA, IC and III antiarrhythmic agents have demonstrated efficacy in suppression of atrial flutter. – In the absence of structural heart disease, class IC are the drugs of choice; class III likewise may be effective. Catheter ablation therapy
RF Ablation of Typical Flutter Cavotricuspid isthmus is the target for typical and reverse typical flutter ablation The endpoint of ablation is bidirectional isthmus block persisting for minutes The precise point of the isthmus that the ablation line should cross is variable, however it is usually midway between the septal and the anterior RA (6 o’clock of the TR in a 45° LAO view)
Oblique View of Right Atrium Crista Terminalis Pectinate Muscle Orifice of Coronary Sinus Superior Vena Cava Fossa Ovalis Eustachian Ridge Inferior Vena Cava Netter F. Atlas of Human Anatomy. 1989;Plate 208.
RF Ablation of Typical Flutter A linear lesion needs to be created to sever the macroreentrant circuit The lesion starts from the tricuspid annulus and runs back to the IVC The lesion must be constant and contain no skips, otherwise the circuit can remain Termination will occur during RF delivery
Catheter Location for Atrial Flutter Ablation Free wall Crista
Isthmus Block: Activation sequence during pacing Proximal CS pacingLow RA pacing
Assessing isthmus block during CS pacing Block No block No CTI blockCTI block
Other Markers of Conduction Block Increase in trans-isthmus conduction time differential pacing Double potentials ms interval between potentials along entire ablation line Reversal of electrogram polarity on the opposite side of the ablation line from the pacing site Change in p-wave morphology pacing lateral to the ablation line
Isthmus Block: Differential pacing
Isthmus Block: Double potentials
Isthmus Block: Change in electrogram configuration beyond the line of ablation
Complicating factors in atrial flutter ablation
Fragmentation of isthmus electrograms after radiofrequency application
Fragmented continuous electrogram at the gap of the ablation line
Complications of Flutter Ablation Pain: especially if close to the septal RA - pain is usually controlled by IV sedation AV block: especially if RFA applicated close to low portion of Koch' triangle around the CS ostium - Av block may be related to vagal effect - AV block was completely reversible spontaneously or preventable by atropine There are no report of tricuspid valve dysfunction or coronary artery obstruction
Clinical course and recurrences Since adoption of isthmus block as an endpoint, recurrence rates less than 10% are commonly reported. Appearance of other types of flutter during follow-up is unusual. The main problem during follow-up is atrial fibrillation, usually paroxysmal form, in ≥ 30% of patients.
Summary Atrial flutter ablation is effective way for Atrial Flutter control with low risk of complications. Improved mapping techniques along with enhanced imaging will improve the success rate of flutter ablations.