01Approach to the Critical Patient/attcp52

Immediate priorities

›Hemodynamic instability triggers

›Hypotension SBP < 90 mmHg

›Synchronized cardioversion immediately

›50 to 100 J biphasic starting dose

›Altered mental status with tachycardia

›Assume hemodynamic compromise

›Escalate to resuscitation bay

›Rate > 150 bpm with signs of shock

›Do not delay cardioversion for adenosine trial

›AHA 2025 ACLS Class I recommendation

›Airway and oxygenation

›Oxygen saturation target >= 94%

›Nasal cannula or mask titrated to target

›HFNC if respiratory compromise present

›Wide complex tachycardia

›Treat as VT until proven otherwise

›Avoid adenosine if pre-excitation suspected

Monitoring and stabilization

›Monitoring bundle

›Continuous cardiac monitoring

›12-lead ECG immediately

›Rhythm strip documentation

›IV access bilateral large bore

›12-lead ECG before and after intervention

›Pulse oximetry continuous

›Vital signs cadence

›Every 5 minutes during active tachycardia

02History/hx64

Symptom characterization

›Primary symptoms

›Palpitations

›Abrupt onset suggests microreentrant mechanism

›Gradual warm-up over 5 to 10 seconds suggests automaticity

›Lightheadedness or presyncope

›Hemodynamic compromise indicator

›Syncope requires urgent evaluation

›Chest discomfort or dyspnea

›Demand ischemia concern with rapid rate

›Heart failure decompensation concern

›Episode characterization

›Paroxysmal vs incessant pattern

›Incessant AT risks tachycardia-mediated cardiomyopathy in up to 10% of patients

›Paroxysmal episodes may allow watchful waiting

›Duration and frequency

›Minutes vs hours vs days

›Prior episodes and prior workup

›Termination pattern

›Spontaneous abrupt termination suggests microreentry

›Vagal maneuver response history

Risk factors

›Cardiac history

›Structural heart disease

›Cardiomyopathy

›Valvular disease

›Prior atrial surgery or ablation

›Congenital heart disease repair

03Physical Exam/exam65

Vitals and general

›Hemodynamic snapshot

›Heart rate

›Typically 100 to 250 bpm in focal AT

›Rate variability in MAT

›Blood pressure

›SBP < 90 mmHg triggers urgent intervention

›Pulse pressure narrowing

›Oxygen saturation

›Room air baseline

›Exertional desaturation

›General appearance

›Diaphoresis

›Sympathetic activation

›Hemodynamic compromise marker

›Distress level

›Inability to speak full sentences

›Anxiety or agitation

Cardiovascular exam

›Rhythm assessment

›Regular rhythm

›Focal AT pattern

›Contrast with irregularly irregular AF

›Irregularly irregular

›MAT pattern

›AF differentiation required

›Jugular venous pulsations

›Cannon A waves if AV dissociation present

04Differential Diagnosis/ddx53

Life-threatening mimics

›Ventricular tachycardia

›Wide complex tachycardia

›ICD-10 I47.2

›AV dissociation on ECG

›Differentiating features

›Fusion beats and capture beats

›Brugada criteria application

›Pre-excited tachycardia with WPW

›AF with pre-excitation

›ICD-10 I45.6

›Irregular wide complex tachycardia at very rapid rates

›Risk of sudden cardiac death

›Avoid AV nodal blocking agents

›Cardioversion preferred

›Atrial flutter with 2:1 conduction

›Sawtooth pattern

›ICD-10 I48.3 or I48.4

›Atrial rate typically 300 bpm

›Differentiating feature

›No isoelectric baseline between flutter waves

›Adenosine reveals flutter waves

SVT mimics

›AVNRT

›Most common SVT

›ICD-10 I47.1

›Short RP tachycardia

›ECG features

05Laboratory Tests/lt55

Core metabolic labs

›Electrolytes

›Potassium

›Hypokalemia lowers arrhythmia threshold

›Target replete to > 4.0 mmol/l before antiarrhythmics

›Magnesium

›Hypomagnesemia key trigger especially in MAT

›IV magnesium even if levels normal in MAT

›Calcium

›Hypercalcemia arrhythmia risk

›Hypocalcemia potentiates QT prolongation

›Renal function

›Creatinine and eGFR

›Digoxin dosing and toxicity threshold adjustment

›Antiarrhythmic dosing adjustment

›BUN

›Dehydration context

›Prerenal state identification

Endocrine and toxicology

›Thyroid function

›TSH

›Rule out hyperthyroidism as precipitant

›Obtain in new-onset AT without clear cause

›Free T4 if TSH suppressed

›Thyrotoxicosis severity

›Guides urgency of endocrine consultation

›Drug levels and toxicology

›Digoxin level

06Diagnostic Tests/dt62

Scoring Systems

›SVT risk stratification

›No validated emergency tachycardia score specific to AT

›Clinical gestalt and hemodynamic assessment primary

›Mechanism determination guides therapy

›CHA2DS2-VASc not applicable to focal AT

›Applies to AF thromboembolic risk

›Do not conflate with AT management

›Tachycardia-mediated cardiomyopathy risk

›Incessant AT duration as risk stratifier

›Weeks to months of rapid rate required to cause cardiomyopathy

›EF typically normalizes after successful treatment

›Echo-based EF at presentation

›EF < 40% with incessant AT suggests tachycardia-mediated cardiomyopathy

›Urgent rate control or ablation indicated

MRI

›Cardiac MRI role in AT

›Limited acute utility

›Not a first-line emergency diagnostic

›Rate and motion artifact limit image quality during tachycardia

›Pre-ablation structural assessment

›Scar characterization in structural heart disease

›Congenital anatomy in complex AT

›Contraindications

›Hemodynamic instability

›Non-MRI compatible devices or implants

CT

›CT indications in AT evaluation

07Disposition/dispo46

Admission criteria

›Indications for hospital admission

›Hemodynamic instability

›SBP < 90 mmHg at any point

›Cardioversion required in ED

›Refractory tachycardia

›Failure to terminate or rate control with ED management

›IV antiarrhythmic initiation required

›Suspected tachycardia-mediated cardiomyopathy

›New low EF with incessant AT

›Heart failure symptoms

›Digoxin toxicity

›AT with AV block pattern

›Telemetry and digoxin-specific Fab consideration

›MAT with pulmonary decompensation

›Acute COPD exacerbation or pneumonia trigger

›Oxygen requirement

›ICU indications

›Shock requiring vasopressors

›Tachyarrhythmia contributing to cardiogenic shock

›Hemodynamic monitoring required

›Wide complex tachycardia requiring urgent EP consultation

›Uncertain mechanism

›Failed cardioversion

Discharge criteria

›Safe discharge requirements

›Conversion to sinus rhythm

›Documented on 12-lead ECG

08Treatment/t145

Acute stabilization

›Vagal maneuvers first line

›Modified Valsalva maneuver

›Strain for 15 seconds then supine with passive leg raise

›Success rate approximately 50% with leg raise modification

›Carotid sinus massage

›Right side first

›Avoid with carotid bruit or stenosis

›Mechanism

›Increases vagal tone transiently

›May terminate reentrant AT or reveal atrial activity in automatic AT

Pharmacologic acute treatment

›Adenosine

›Adenosine 6 mg rapid IV push

›Follow immediately with 20 mL normal saline flush

›If no response after 1 to 2 minutes give 12 mg rapid IV push

›Second dose

›12 mg IV rapid push

›May repeat 12 mg once more if needed

›Diagnostic and therapeutic role

›Terminates triggered or microreentrant AT

›Transiently suppresses automatic AT revealing underlying atrial activity

›Reveals atrial flutter waves

›Contraindications

›Severe asthma or bronchospasm

›Pre-excitation with WPW

›Second or third degree AV block

›IV diltiazem for rate control or termination

›Diltiazem 20 mg IV over 2 minutes

›If no response after 15 minutes give 25 mg IV

›Maintenance infusion 5 to 15 mg/hour if needed

›Contraindications

›HFrEF with EF < 40%

›Hemodynamic instability

›Pre-excitation with WPW

›Evidence base

›Class IIa recommendation 2015 ACC/AHA/HRS SVT guideline

›IV verapamil

›Verapamil 5 mg IV over 2 minutes

›May repeat 5 to 10 mg every 15 to 30 minutes

›Maximum 30 mg total

›Contraindications

›HFrEF

›Wide complex tachycardia

›Hemodynamic instability

›Alternative to diltiazem

›Similar efficacy for focal AT

›Not preferred over diltiazem in emergency setting

›IV beta-blockers

›Metoprolol tartrate 5 mg IV over 2 minutes

›May repeat every 5 minutes up to 3 doses

›Total maximum 15 mg IV

›Esmolol IV loading

›500 mcg/kg bolus over 1 minute

›Maintenance 50 mcg/kg/minute

›Titrate 25 to 50 mcg/kg/minute every 5 to 15 minutes

›Maximum 300 mcg/kg/minute

›Preferred when structural disease relative contraindication to CCB

›Caution in severe bronchospastic disease

›Class IIa recommendation 2015 ACC/AHA/HRS SVT guideline

›IV amiodarone

›Amiodarone 150 mg IV over 10 minutes

›Followed by 1 mg/minute infusion for 6 hours

›Then 0.5 mg/minute for 18 hours

›Preferred when reduced EF or heart failure

›Does not worsen LV function significantly

›Class IIa recommendation for AT with reduced EF

›Caution

›Phlebitis with peripheral infusion

›QT prolongation monitoring

Electrical cardioversion

›Synchronized cardioversion

›50 to 100 J biphasic initial energy

›Escalate if unsuccessful

›Sedation with procedural agent before cardioversion

›Indications

›Hemodynamic instability refractory to medications

›Patient preference for rapid termination

›Limitations for automatic AT

›Cardioversion unlikely to terminate automatic AT mechanism

›Rate control agents preferred for automatic AT

›Evidence

›Class I recommendation for unstable SVT AHA 2025 ACLS guideline

Multifocal AT specific treatment

›Treat underlying condition first

›COPD exacerbation management

›Bronchodilators and corticosteroids

›Oxygen with target 88 to 92% in COPD

›Correct metabolic derangements

›Hypoxia correction priority

›Acid-base normalization

›IV magnesium

›Magnesium sulfate 2 g IV over 10 to 20 minutes

›Even if magnesium level is normal

›Repeat 2 g if no response and levels permit

›Mechanism

›Stabilizes automaticity in multiple atrial foci

›Class IIb recommendation for MAT

›Rate control in MAT

›Verapamil or diltiazem preferred in pulmonary disease

›Diltiazem 20 mg IV as initial dose

›Avoid non-selective beta-blockers in bronchospastic disease

›Metoprolol after respiratory stabilization

›Use with caution in active bronchospasm

›5 mg IV if respiratory status allows

›Cardioversion not effective for MAT

›Not recommended for MAT

›Class III harm recommendation

Long-term oral pharmacotherapy

›First-line oral agents

›Beta-blockers

›Metoprolol succinate 25 to 100 mg PO daily extended release

›Atenolol 25 to 100 mg PO daily as alternative

›Diltiazem extended release

›120 to 360 mg PO daily

›Rate and rhythm control properties

›Verapamil extended release

›120 to 480 mg PO daily divided

›Class IIa recommendation for symptomatic AT

›Second-line antiarrhythmic agents

›Flecainide

›50 to 150 mg PO twice daily

›Contraindicated in structural or ischemic heart disease

›Pill-in-the-pocket option for infrequent episodes

›Propafenone

›150 to 300 mg PO three times daily

›Contraindicated in structural or ischemic heart disease

›Beta-blocking properties limit in bronchospastic disease

›Third-line specialist-supervised agents

›Sotalol

›80 to 160 mg PO twice daily

›QT monitoring required

›Renal dose adjustment necessary

›Amiodarone

›200 mg PO daily maintenance after loading

›Reserve for refractory cases or reduced EF

›Long-term organ toxicity monitoring required

›Dofetilide

›Specialist initiation with telemetry required

›QT-dependent dosing protocol

›Catheter ablation

›First-line for recurrent symptomatic focal AT

›Acute success rate > 90 to 95%

›Recurrence rate < 5%

›Risk of inadvertent AV block < 1%

›Higher risk for septal AT near AV node

›Patient counseling required pre-procedure

›Class I recommendation 2015 ACC/AHA/HRS SVT guideline

›Preferred over long-term antiarrhythmic therapy

›Cardiology or EP referral for ablation candidacy

09Special Populations/sp83

Pregnancy

›Pregnancy-specific considerations

›Increased SVT susceptibility

›Elevated catecholamines and blood volume

›Hormonal effects on ion channels

›Fetal heart rate monitoring

›Maternal tachycardia affects fetal status

›Obstetrics consultation in second and third trimester

›Acute management in pregnancy

›Vagal maneuvers first

›Safe in all trimesters

›Modified Valsalva preferred

›Adenosine safe in pregnancy

›Short half-life limits fetal exposure

›Class IIa recommendation during pregnancy

›Standard doses 6 mg then 12 mg IV

›Metoprolol acceptable for rate control

›Category C but widely used in pregnancy

›Monitor for fetal bradycardia and IUGR

›Verapamil use with caution

›May cause fetal bradycardia

›Avoid in first trimester if possible

›Agents to avoid in pregnancy

›Amiodarone

›Fetal thyroid dysfunction and IUGR risk

›Reserve for life-threatening refractory AT only

›Flecainide and propafenone

›Limited safety data in pregnancy

›Specialist guidance required

›Sotalol and dofetilide

›Avoid due to fetal risk

›Category B/D designations

Geriatric

›Physiologic changes in older adults

›Reduced sinoatrial and AV nodal function

›Increased sensitivity to AV nodal blocking agents

›Start at lower doses of diltiazem or beta-blockers

›Reduced renal clearance

›Digoxin dosing careful adjustment

›Sotalol renal dosing required

›Medication safety considerations

›Verapamil caution

›Constipation and hypotension risk higher

›Drug interaction risk with polypharmacy

›QT prolongation risk elevated

›Avoid multiple QT-prolonging agents

›Baseline QT measurement required

›Fall risk with antiarrhythmics

›Dizziness and hypotension more common

›Orthostatic blood pressure assessment

›Multifocal AT in older adults

›Higher prevalence of pulmonary disease substrate

›COPD and heart failure common comorbidities

›Treat underlying disease as primary intervention

›Theophylline use in older COPD patients

›Drug level monitoring essential

›Narrow therapeutic window

Pediatrics

›Pediatric AT features

›Focal AT accounts for up to 15% of SVT in children

›Often incessant in infants leading to cardiomyopathy

›Higher rate of spontaneous resolution in infants vs adults

›Presentation differences

›Infants present with irritability poor feeding and tachypnea

›Older children report palpitations

›Acute management in pediatrics

›Vagal maneuvers age-appropriate

›Ice to face for infants

›Valsalva for older children

›Adenosine weight-based dosing

›0.1 mg/kg IV rapid push initial dose

›Maximum 6 mg initial dose

›Second dose 0.2 mg/kg up to 12 mg maximum

›Synchronized cardioversion if hemodynamically unstable

›0.5 to 1 J/kg initial

›Escalate to 2 J/kg if needed

›Long-term pediatric management

›Catheter ablation effective in children > 15 to 20 kg

›Success rates > 90% in pediatric EP programs

›Preferred over long-term antiarrhythmics in older children

›Propranolol first-line oral agent in infants

›1 to 4 mg/kg/day divided three to four times daily

›Monitor for hypoglycemia in neonates

›Digoxin in infants with reduced EF

›8 to 10 mcg/kg/day maintenance divided twice daily

›Serum level monitoring required

10Background/b75

Epidemiology

›Prevalence and incidence

›AT accounts for 10 to 17% of SVTs referred for ablation

›2015 ACC/AHA/HRS SVT Guideline estimate

›True prevalence higher as many not referred

›Age distribution

›Focal AT occurs across all ages including young adults

›Prevalence increases with age

›Sex distribution

›Slight female predominance for SVT overall

›No strong sex predominance specifically for AT

›Disease burden

›Tachycardia-mediated cardiomyopathy in up to 10% of incessant cases

›EF recovers after successful treatment in most patients

›Underdiagnosed as a cause of cardiomyopathy

›MAT mortality related to underlying disease severity

›High in-hospital mortality driven by COPD or sepsis substrate

›MAT itself not independently lethal

›High premature atrial complex burden as risk factor

›PAC burden > 500 per 24 hours increases AF progression risk

›Shared atrial substrate with AT

Pathophysiology

›Mechanisms of focal AT

›Enhanced automaticity

›Abnormal phase 4 depolarization in ectopic atrial focus

›Warm-up and cool-down phenomenon over 5 to 10 seconds

›Triggered activity

›Delayed or early afterdepolarizations

›Common with catecholamine excess or digoxin toxicity

›Microreentry

›Small reentrant circuit within atrial tissue

›Abrupt onset and termination

›Terminates with adenosine

›Common anatomic origins of focal AT

›Crista terminalis right atrium

›Most common right-sided location

›Pulmonary veins and left atrium

›Especially perimitral region

›Overlap with AF substrate

›Coronary sinus region

›Posteroseptal location

›Para-Hisian region

›Ablation risk of inadvertent AV block

›Multifocal AT pathophysiology

›Multiple ectopic atrial foci

›Triggered by metabolic derangement or catecholamine excess

›Hypoxia and acidosis reduce atrial action potential stability

›Hypomagnesemia

›Magnesium deficiency destabilizes automaticity in multiple foci

›IV magnesium effective even with normal serum levels

Therapeutic Considerations

›Rate control vs rhythm control decision

›Rhythm control preferred for focal AT

›Catheter ablation as definitive therapy

›Antiarrhythmics as temporizing or alternative

›Rate control acceptable for MAT

›Rhythm control not achievable while multiple foci active

›Underlying disease treatment primary goal

›Catheter ablation considerations

›P-wave morphology guides ablation target

›Positive P wave in V1 with negative I and aVL suggests left atrial origin

›Negative P in inferior leads suggests low right atrial or coronary sinus origin

›Electrophysiology study required before ablation

›Gold standard for mechanism determination

›Mapping of earliest atrial activation

›Success and recurrence rates

›Acute success > 90 to 95%

›Recurrence rate < 5% with successful ablation

›Antiarrhythmic selection principles

›Structural heart disease limits drug choice

›Flecainide and propafenone contraindicated with structural or ischemic disease

›Amiodarone or sotalol if antiarrhythmic required with structural disease

›QT monitoring mandatory with sotalol and dofetilide

›Baseline QTc measurement required

›Discontinue if QTc > 500 ms

›Adenosine challenge as diagnostic tool

›AT with AV block visible on adenosine = automatic AT

›AT termination with adenosine = triggered or microreentrant AT

11Patient Discharge Instructions/pdi42

copy discharge instructions

›Atrial tachycardia home care

›Take all medications exactly as prescribed

›Do not skip doses of rate control or antiarrhythmic medications

›Do not stop without speaking to your doctor

›Avoid known triggers

›Caffeine including coffee tea energy drinks and sodas

›Alcohol

›Stimulant drugs or supplements

›Lifestyle measures

›Stay well hydrated

›Regular sleep schedule

›Moderate regular exercise as tolerated

›Vagal maneuver self-treatment

›Modified Valsalva technique

›Blow hard into a syringe or closed lips for 15 seconds

›Immediately lie flat and have someone raise your legs for 15 seconds

›Can terminate many episodes of palpitations

›When to use

›Early in an episode before calling for help

›Only if not lightheaded or unwell

›Return to ER immediately for

›Fainting or near-fainting

›Loss of consciousness during palpitations

›Feeling you are about to pass out

›Chest pain during palpitations

›Pressure squeezing or tightness in chest

›Palpitations lasting more than 15 to 20 minutes

12References/r25

Guidelines and key sources

›Primary guidelines

›2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia

›Page RL et al Journal of the American College of Cardiology 2016

›Comprehensive SVT management including focal AT ablation recommendations

›2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation

›Joglar JA et al Journal of the American College of Cardiology 2024

›Includes SVT differential and antiarrhythmic principles

›AHA 2025 Adult Advanced Life Support Guidelines

›Wigginton JG et al Circulation 2025

›Cardioversion thresholds and ACLS arrhythmia algorithms

›Supporting evidence

›Peng G and Zei PC JAMA 2024 Diagnosis and Management of Paroxysmal SVT

›Practical review of adenosine vagal maneuvers and rate control agents

›Nasir M et al American Family Physician 2023 Common Types of SVT

›Ablation success rates and antiarrhythmic selection

›Helton MR American Family Physician 2015 Common Types of SVT

›Diagnostic approach and initial management

›Coding and terminology

›ICD-10 I47.1 supraventricular tachycardia including focal AT

›SNOMED CT focal atrial tachycardia concept

›ICD-10 I47.2 ventricular tachycardia for differential coding

›Tisdale JE et al AHA Scientific Statement 2020 Drug-Induced Arrhythmias

›Digoxin and theophylline induced AT mechanisms and management

›Nielsen JC et al EHRA/HRS/APHRS/LAHRS Expert Consensus 2020 Risk Assessment in Cardiac Arrhythmias

›Occupational risk stratification and syncope evaluation

Evidence & Review