ACC/AHA GUIDELINE FOR MANAGEMENT OF SVT IN

ADULT PATIENTSDR MAHENDRA

CARDIOLOGY,JIPMER

SVT• tachycardia's having atrial and/or ventricular rates in excess of 100 bpm at rest. • mechanism of which involves tissue from the His bundle or above. SVTs include-• inappropriate sinus tachycardia• AT (including focal and multifocal AT) • macro reentrant AT • junctional tachycardia • AVNRT, and various forms of accessory pathway-mediated reentrant tachycardias.• In this guideline, the term does not include AF.

• prevalence of SVT is 2.25 per 1,000 .• incidence of PSVT is 36 per 100,000 persons per year. • Women have twice the risk of men of developing PSVT .• Individuals >65 years of age have >5 times the risk of younger persons of

developing PSVT.

Clinical History • Modes of presentation- • documented SVT in 38%• palpitations in 22% • chest pain in 5% • syncope in 4%• AF in 0.4% • sudden cardiac death in 0.2%

Algorithm for Short term management of SVT

Differential diagnosis with adenosine

• SPECIFIC TACHYARRHYTHMIAS

Sinus Tachyarrhythmias-

a. Physiological Sinus Tachycardiab. Inappropriate Sinus Tachycardiac. Sinus Node Re-Entry Tachycardia

Inappropriate Sinus Tachycardia• persistent increase in resting heart rate unrelated to the level of physical, emotional,

pathological,or pharmacologic stress. • 1. Enhanced automaticity of the sinus node• 2. Abnormal autonomic regulation of the sinus node with excess sympathetic and reduced

parasympathetic tone. • Diagnosis-• presence of a persistent sinus tachycardia (heart rate more than 100 bpm) during the day with

excessive rate increase in response to activity and nocturnal normalization of rate as confirmed by a 24-hour Holter recording.

• tachycardia (and symptoms) is nonparoxysmal. • P-wave morphology and endocardial activation identical to sinus rhythm.• Exclusion of a secondary systemic cause.

Sinus Node Re-Entry Tachycardia• Diagnosis-• tachycardia and symptoms are paroxysmal.• microreentrant circuit • P-wave is identical to sinus rhythm. • distinguish sinus node reentry from sinus tachycardia are an abrupt onset and

termination • often a longer RP interval than that observed during normal sinus rhythm.• termination occurs with vagal maneuvers or adenosine.• Induction of the arrhythmia is independent of atrial or AV-nodal conduction time.

• Treatment-• no controlled trials of drug prophylaxis for pts with SNRT.• respond to vagal maneuvers, adenosine, amiodarone, beta blockers,

nondihydropyridine calcium-channel blockers, or even digoxin. • EP studies for frequent or poorly tolerated episodes of tachycardia that do not

adequately respond to drug therapy.• Radiofrequency catheter ablation is generally successful.

AVNRT

• Presence of a narrow complex tachycardia with regular R-R intervals and no visible p waves.• P waves are retrograde and are inverted in leads

II,III,avf.• P waves are buried in the QRS complexes –

simultaneous activation of atria and ventricles – most common presentation of AVNRT –66%.• If not synchronous –pseudo s wave in inferior

leads ,pseudo r’ wave in lead V1---30% cases .

Atypical AVNRT• Arrows point to the P wave.• The reentrant circuit involves anterograde conduction over a fast atrioventricular

node pathway, followed by retrograde conduction in a slow atrioventricular node pathway, resulting in a retrograde P wave (negative polarity in inferior leads) with long RP interval.

AVRT

• Typical – RP interval < PR interval• RP interval > 80 milli sec• Atypical –RP interval > PR interval• Concealed bypass tract – only retrograde conduction• Manifest bypass tract– both anterograde and

retrograde.• Electrical alternans –the amplitude of QRS complexes

varies by 5 mm alternatively.

PRinterval RP interval

PR interval

Orthodromic Atrioventricular Reentrant Tachycardia• The reentrant circuit involves anterograde conduction over the

atrioventricular node, followed by retrograde conduction over an accessory pathway, which results in a retrograde P wave with short RP interval.

Junctional Tachycardia

• 1. Junctional Tachycardia-• origin from the AV node or His bundle• heart rates of 110 to 250 bpm and a narrow complex or typical BBB conduction

pattern• Atrioventricular dissociation is often present• arrhythmia is thought to be either abnormal automaticity or triggered activity. • uncommon in adults • typically seen in infants postoperatively, after cardiac surgery for congenital heart

disease.

• 2. Nonparoxysmal Junctional Tachycardia• benign arrhythmia• narrow complex tachycardia with rates of 70 to 120 bpm.• enhanced automaticity arising from a high junctional focus or in response to a triggered mechanism• cannot be terminated by pacing maneuvers. • Cause-• digitalis toxicity,• postcardiac surgery• hypokalemia,• myocardial ischemia. • chronic obstructive lung disease with hypoxia• inflammatory myocarditis.

Focal AT and MAT

AT• Rapid (usually <250 beats/ min), relatively regular rhythms that

originate in the atrial musculature.• Mechanisms include abnormal automaticity and triggered activity.• Foci are most frequently found in the pulmonary veins in the LA and

the crista terminalis in the right atrium.• Myocardial infarction, nonischemic heart disease,obstructive lung

disease, serum electrolyte disorders, and drug toxicity

• RP intervals can be variable • RP often > PR• (Example slower than more common rate 150-250 beats per min)

Atrial Tachycardia

V1

Differs fromAV nodal or AV reentrantSVT

MAT• rapid, irregular rhythm with at least 3 distinct morphologies of P waves on the

surface ECG• distinct isoelectric period between P waves.• The P-P, PR, and R-R intervals are variable. • associated with pulmonary disease, pulmonary hypertension, coronary disease,

and valvular heart disease , hypomagnesemia and theophylline therapy.• first-line treatment is management of the underlying condition

Multifocal Atrial Tachycardia

ECG Characteristics: Discrete P waves with at least 3different morphologies.

Absence of one dominant atrial pacemaker

Atrial rate > 100 bpm.

The PP, PR, and RR intervals all vary.

Atrial Flutter• Usually a single, irritable foci in the atria (right) • AV node protects the ventricles by blocking some of the atrial

impulses (decremental conduction)• P waves take on a “sawtooth” appearance and are called F waves or

flutter waves• Atrial rhythm and ventricular response are usually regular• Atrial rate 250-350 beats/min. Ventricular rate varies depending

on the number of impulses the AV node is blocking• No P waves or PR interval• QRS normal width or with aberrancy

Special population• ADULT ACHD • PREGNANCY• OLDER POPULATION

ACHD• SVT is observed in 10% to 20% of ACHD . • increased risk of heart failure, stroke, and SCD.• mechanism of SVT in ACHD patients is macro reentrant AT, which accounts for at

least 75% of SVT

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