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Supraventricular Tachycardia (SVT)
Cardiovascular Presentations
Abdominal aortic aneurysm
Acute coronary syndrome (NSTEMI)
Acute coronary syndrome (STEMI)
Acute decompensated heart failure
Acute limb ischemia
Acute mesenteric ischemia
Aortic dissection
Aortic stenosis
Atrial fibrillation and flutter
Bradyarrhythmia and heart block
Cardiac arrest
Deep vein thrombosis
Myocarditis
Pericarditis
Pulmonary embolism
Stable angina
Superficial thrombophlebitis
Superior vena cava syndrome
Supraventricular tachycardia
Syncope (cardiogenic)
Unstable angina
Ventricular tachycardia
Respiratory Presentations
Acute bronchitis
Acute respiratory failure
Aspiration pneumonia
Asthma exacerbation
Bronchiolitis
Community-acquired pneumonia
COVID-19 pneumonia
COPD exacerbation
Croup
Croup (laryngotracheobronchitis)
Epiglottitis
Hemothorax
Hospital-acquired pneumonia
Pleural effusion
Pneumothorax (traumatic)
Pulmonary contusion
Spontaneous pneumothorax
Neurological Presentations
Bell's palsy
Benign paroxysmal positional vertigo
Brain abscess
Cauda equina syndrome
Cervical radiculopathy
Concussion (mild traumatic brain injury)
Encephalitis
Guillain-Barré syndrome
Hemorrhagic stroke (intracerebral)
Ischemic stroke
Lumbar radiculopathy
Malignant spinal cord compression
Migraine
Peripheral neuropathy (acute)
Retropharyngeal abscess
Schizophrenia (acute exacerbation)
Seizure (breakthrough:known epilepsy)
Seizure (first-time)
Spinal cord injury
Status epilepticus
Subarachnoid hemorrhage
Tension headache
Transient ischemic attack
Traumatic brain injury (moderate-severe)
Vestibular neuritis
Viral meningitis
Gastrointestinal Presentations
Acute appendicitis
Acute cholecystitis
Acute diverticulitis
Acute pancreatitis
Anal fissure
Choledocholithiasis and cholangitis
Clostridioides difficile colitis
Gastritis
Gastroenteritis (viral and bacterial)
Gastroesophageal reflux disease
Incarcerated or strangulated hernia
Inflammatory bowel disease flare
Large bowel obstruction
Lower GI hemorrhage
Peptic ulcer disease
Perforated viscus
Small bowel obstruction
Upper GI hemorrhage
Genitourinary and Reproductive Presentations
Acute prostatitis
Acute urinary retention
Ectopic pregnancy
Epididymitis
Orchitis
Ovarian torsion
Paraphimosis
Pelvic inflammatory disease
Priapism
Pyelonephritis
Renal laceration
Ruptured ovarian cyst
Testicular torsion
Tubo-ovarian abscess
Urinary tract infection (uncomplicated)
Urolithiasis (renal colic)
Vaginal bleeding (non-pregnant)
Infectious Disease Presentations
Acute sinusitis
Acute tonsillitis
Acute upper respiratory infection
Animal bite
Bacterial meningitis
Cellulitis
Conjunctivitis (bacterial)
Dental abscess
Endocarditis
Febrile neutropenia
Fournier gangrene
Hand-foot-mouth disease
Hepatitis (acute)
Herpes zoster
HIV-related illness
Human bite
Impetigo
Infected diabetic foot ulcer
Infectious mononucleosis
Influenza
Necrotizing fasciitis
Osteomyelitis
Otitis externa
Parasitic infection
Periorbital cellulitis
Peritonsillar abscess
Scabies
Sepsis
Septic arthritis
Spontaneous bacterial peritonitis
Tick-borne illness (Lyme disease)
Tinea infection
Tuberculosis
Viral exanthem
Wound infection
Trauma Presentations
Achilles tendon rupture
ACL and mceniscus tear
Ankle fracture
Ankle sprain
Burn
Calcaneus fracture
Cervical spine fracture
Clavicle fracture
Dental avulsion
Distal radius fracture
Drowning
Elbow fracture and dislocation
Electrical injury
Facial bone fracture
Facial laceration
Femur fracture
Fingertip amputation
Forearm fracture (radius and ulna)
Frostbite
Hand:finger laceration
Heat exhaustion
Heat stroke
Hip fracture
Humeral shaft fracture
Knee dislocation
Knee sprain
Lightning injury
Mandible fracture
Metacarpal fracture
Metatarsal fracture
Muscle strain
Nasal fracture
Non-accidental trauma
Orbital fracture
Patella fracture
Phalanx fracture (finger)
Proximal humerus fracture
Pulmonary contusion
Rib fracture
Rotator cuff tear (acute traumatic)
Scalp laceration
Scaphoid fracture
Shoulder dislocation
Skull fracture
Splenic laceration
Sternal fracture
Supracondylar pediatric fracture
Tendon laceration (hand:wrist)
Thoracic and lumbar spine fracture
Tibia:fibula fracture
Tibial plateau fracture
Toe fracture
Traumatic epistaxis
Traumatic hyphema
Toxicologic Presentations
Acetaminophen toxicity
Alcohol intoxication
Alcohol withdrawal
Anticholinergic toxicity
Anticoagulant overdose
Benzodiazepine overdose
Benzodiazepine:sedative overdose
Beta-blocker and calcium channel blocker toxicity
Carbon monoxide poisoning
Caustic ingestion
Digoxin toxicity
Drug eruption
Foreign body ingestion
Opioid intoxication
Opioid overdose
Opioid withdrawal
Organophosphate
Salicylate toxicity
Serotonin syndrome
Stimulant intoxication (cocaine, methamphetamine)
Tricyclic antidepressant overdose
Psychiatric Presentations
Acute anxiety
Acute psychosis
Agitation:behavioral emergency
Bipolar disorder
Conversion disorder
Major depressive episode
Neuroleptic malignant syndrome
Suicidal ideation and attempt
Musculoskeletal and Rheumatologic Presentations
Acute low back pain (mechanical)
Bursitis
Cervical radiculopathy
Costochondritis
Gout (acute)
Lumbar radiculopathy
Pseudogout
Tendinitis
Dermatology Presentations
Acute eczema (Eczema acute flare)
Allergic contact dermatitis
Erythema multiforme
Henoch-Schönlein purpura
Pressure injury
Psoriasis (acute flare)
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Urticaria (acute)
Environmental and Exposure Presentations
Envenomation (snake, spider, insect)
High-altitude illness
Hypothermia
Hematologic and Oncologic Presentations
Acute chest syndrome
Coagulopathy
Hyperviscosity syndrome
Sickle cell crisis (vaso-occlusive)
Symptomatic anemia
Thrombocytopenia (severe)
Tumor lysis syndrome
Pediatric-Specific Presentations
Bronchiolitis
Croup
Emergency delivery
Febrile seizure
Kawasaki disease
Neonatal jaundice
Neonatal sepsis
Nursemaid's elbow
Pediatric fever 0 to 28 days
Pediatric fever 29 to 60 days
Pediatric fever 61 to 90 days
Pyloric stenosis
Slipped capital femoral epiphysis
Intussusception
Endocrine and Metabolic Presentations
Adrenal crisis
Diabetic ketoacidosis
Hypercalcemia
Hyperosmolar hyperglycemic state
Hypertensive emergency
Hypertensive urgency
Hypoglycemia
Myasthenia gravis crisis
Myxedema coma
Severe hyperkalemia
Severe hyponatremia
Thyroid storm
ENT and Maxillofacial Presentations
Acute laryngitis
Acute otitis media
Acute pharyngitis
Cerumen impaction
Epistaxis (anterior)
Nasal foreign body
Otitis externa
Tympanic membrane perforation
Ophthalmologic Presentations
Acute angle-closure glaucoma
Central retinal artery occlusion
Chemical eye injury
Corneal abrasion
Corneal ulcer
Globe rupture
Ocular foreign body
Orbital cellulitis
Retinal detachment
Obstetric Presentations
Hyperemesis gravidarum
Painful vaginal bleeding in pregnancy
Placenta previa
Placental abruption
Preeclampsia:eclampsia
Preterm labor
Threatened:inevitable:incomplete abortion
Systemic and Miscellaneous Presentations
Anaphylaxis
Angioedema
Cannabis-induced hyperemesis
Supraventricular Tachycardia (SVT)
POCUS
Procedures
Calculators
Resuscitation
ECG Guide
Back
Clinical Assessment Checklist
Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Immediate stabilization
Hemodynamic assessment on arrival
▶
If hypotension, altered mental status, acute heart failure, or ischemic chest pain
▶
Immediate synchronized cardioversion (Class I recommendation)
Starting energy 50 to 100 J biphasic
Sedation if patient is conscious
If hemodynamically stable
▶
Rhythm identification before pharmacologic intervention
12-lead ECG as first step
Airway and oxygen
▶
SpO2 target >= 94% on supplemental oxygen
▶
High-flow oxygen for hemodynamic instability
IV access established immediately
Resuscitation bay for unstable presentation
▶
Continuous cardiac monitoring
Defibrillator at bedside
Rhythm identification
ECG interpretation priorities
▶
QRS width
▶
Narrow complex QRS <= 120 ms favors SVT
Wide complex QRS > 120 ms requires VT exclusion
Regularity
▶
Regular rhythm favors AVNRT, AVRT, or atrial flutter with fixed block
Irregularly irregular favors atrial fibrillation or multifocal atrial tachycardia
P wave relationship to QRS
▶
P buried in or just after QRS favors AVNRT
Short RP interval favors AVRT
Long RP interval favors atypical AVNRT or focal atrial tachycardia
Pre-excitation screen
▶
Delta wave or short PR on baseline ECG indicates WPW
▶
Avoid adenosine, verapamil, and diltiazem in pre-excited AF
Pre-excited AF is irregular wide complex tachycardia; can precipitate VF with AV nodal blockers
Monitoring and targets
Continuous monitoring bundle
▶
Cardiac monitor throughout treatment
▶
Document rhythm conversion moment
Post-conversion ECG for baseline assessment
Blood pressure every 5 minutes during treatment
▶
SBP < 90 mmHg triggers escalation to cardioversion
SpO2 continuous
▶
Respiratory decompensation during adenosine administration anticipate
Escalation triggers
▶
Failure of two pharmacologic attempts
▶
Proceed to synchronized cardioversion
Electrophysiology consultation for refractory cases
New hemodynamic deterioration during treatment
▶
Do not delay cardioversion for additional drug trials
Resuscitation team activation
Consultation triggers
Cardiology or electrophysiology consultation
▶
First episode SVT in young patient for ablation discussion
▶
Ablation curative in > 95% of AVNRT and AVRT cases
Known WPW with arrhythmia
▶
High-risk accessory pathway assessment
Recurrent SVT failing pharmacologic prophylaxis
▶
Long-term rhythm management planning
History
Symptom characteristics
Core symptoms
▶
Palpitations
▶
Prevalence 86% in paroxysmal SVT
Abrupt flip-switch onset and termination hallmark of PSVT
Chest discomfort
▶
Prevalence 47% in paroxysmal SVT
Distinguish from ischemic chest pain requiring urgent ECG
Dyspnea
▶
Prevalence 38%
Often exertional in context of elevated heart rate
Lightheadedness or presyncope
▶
Prevalence 19%
True syncope rare and more often vagally mediated than from SVT directly
Episode characterization
▶
Duration and frequency of episodes
▶
Self-terminating versus requiring ED presentation
Escalating frequency as indicator for prophylaxis or ablation
Polyuria during or after episodes
▶
Classic for SVT due to atrial natriuretic peptide release
Distinguishes SVT from panic disorder
Prior episodes, prior ED visits, prior adenosine use
▶
Prior ablation and recurrence timeline
Triggers and risk factors
Common triggers
▶
Caffeine, alcohol, energy drinks
▶
Dietary history including supplement use
Stimulants
▶
Cocaine, methamphetamine, MDMA, amphetamines
Exercise and emotional stress
▶
Situational pattern
Sleep deprivation
▶
Occupational and lifestyle context
Clinical risk factors
▶
Female sex
▶
Approximately 2x higher risk than males
Age > 65 years
▶
Over 5x higher risk than younger individuals
Comorbidities associated with SVT
▶
Chronic pulmonary disease 15.7%
Diabetes 12.5%
Heart failure 8.4%
Cerebrovascular disease 7.8%
Lone PSVT (no cardiovascular disease) accounts for 39% of cases
▶
Younger patients mean age 37 years
Faster rates mean 186 bpm
Prior cardiac history
Relevant past history
▶
Known WPW syndrome or prior delta wave on ECG
▶
High-risk if prior pre-excited AF episode
Prior catheter ablation
▶
Substrate and recurrence pattern
Structural heart disease
▶
Valvular disease, cardiomyopathy, congenital heart disease
Thyroid disease
▶
Hyperthyroidism as trigger or contributor
Family history
▶
Sudden cardiac death in first-degree relatives
▶
WPW with autosomal dominant familial preexcitation syndrome (rare)
Cardiomyopathy or long QT syndrome
▶
Relevant for safety of antiarrhythmic selection
Occupational relevance
▶
Pilots and commercial drivers
▶
Fitness-for-duty implications of SVT diagnosis
Physical Exam
Vitals and general
Hemodynamic snapshot
▶
Heart rate
▶
Typical SVT range 150 to 250 bpm
Rate < 150 bpm consider sinus tachycardia or atrial flutter with variable block
Blood pressure
▶
SBP < 90 mmHg indicates hemodynamic instability requiring cardioversion
MAP < 65 mmHg is threshold for urgent intervention
Respiratory rate and SpO2
▶
Respiratory distress may reflect underlying heart failure or anxiety
Temperature
▶
Fever as potential trigger (infection, thyroid storm)
Cardiovascular exam
Cardiac findings
▶
Regular rapid rhythm on auscultation
▶
Irregular rhythm suggests atrial fibrillation or multifocal atrial tachycardia
Jugular venous pulsations
▶
Cannon A waves classic for AVNRT (simultaneous atrial and ventricular contraction)
Frog sign visible neck pulsations during AVNRT
Murmurs
▶
Valvular disease as substrate for arrhythmia
Peripheral perfusion
▶
Cool extremities, prolonged capillary refill as markers of low output state
Systemic exam
Thyroid
▶
Thyroid enlargement or tenderness
▶
Hyperthyroidism as treatable trigger
Carotid bruits before carotid sinus massage
▶
Contraindication to carotid massage if bruit present
Pulmonary exam
▶
Crackles suggesting pulmonary edema
▶
Heart failure precipitated or worsened by tachycardia
Neurologic
▶
Mental status assessment
▶
Altered consciousness requires immediate cardioversion not pharmacologic trial
Agitation may reflect anxiety but do not delay rhythm control if unstable
PITFALLS
Diagnostic pitfalls
▶
Assuming narrow complex tachycardia is always benign
▶
Hemodynamic tolerance does not exclude serious underlying substrate
Missing pre-excitation
▶
Delta wave on baseline ECG changes entire management algorithm
Giving verapamil in WPW with AF can cause VF
Misidentifying atrial flutter as SVT
▶
2:1 atrial flutter commonly presents at 150 bpm
Adenosine uncovers flutter waves without terminating rhythm
Differential Diagnosis
Life-threatening arrhythmias
Ventricular tachycardia
▶
ICD-10 I47.2
▶
Wide complex tachycardia QRS > 120 ms
AV dissociation, fusion beats, capture beats favor VT
Brugada algorithm or Vereckei algorithm for differentiation
Pre-excited atrial fibrillation in WPW
▶
ICD-10 I45.6 (WPW syndrome)
▶
Irregular wide complex tachycardia
Rates can exceed 300 bpm via accessory pathway
Avoid adenosine, diltiazem, verapamil, digoxin
Atrial flutter with 1:1 conduction
▶
Very rapid ventricular rate 250 to 300 bpm
▶
Associated with accessory pathway or class Ic antiarrhythmic use
Hemodynamic collapse risk
Supraventricular tachycardia subtypes
AVNRT (atrioventricular nodal reentrant tachycardia)
▶
ICD-10 I47.1
▶
Most common PSVT subtype 60%
P wave buried in or just after QRS
Responds to adenosine or vagal maneuvers
AVRT (atrioventricular reentrant tachycardia)
▶
ICD-10 I47.1
▶
30% of PSVT; requires accessory pathway
Short RP interval in orthodromic AVRT
Wide complex in antidromic AVRT
Focal atrial tachycardia
▶
ICD-10 I47.1
▶
10% of PSVT
Distinct P wave morphology before QRS
Less responsive to adenosine than AVNRT or AVRT
Common mimics
Sinus tachycardia
▶
ICD-10 R00.0
▶
Gradual onset and offset
Identifiable upright P waves before every QRS in leads II, aVF
Rate rarely exceeds 150 bpm at rest; treat underlying cause
Atrial flutter with 2:1 block
▶
ICD-10 I48.3
▶
Classic rate 150 bpm
Sawtooth flutter waves in leads II, III, aVF
Adenosine increases block to reveal flutter without terminating
Atrial fibrillation
▶
ICD-10 I48.0, I48.1, I48.2
▶
Irregularly irregular rhythm
No discrete P waves
Multifocal atrial tachycardia
▶
ICD-10 I47.1
▶
Three or more distinct P-wave morphologies
Associated with COPD and hypoxia
Anxiety and panic disorder
▶
ICD-10 F41.0
▶
Sinus tachycardia without abrupt onset or offset
Gradual rate fluctuation
Diagnosis of exclusion after ECG documentation
Laboratory Tests
Essential labs
Electrolytes
▶
Potassium
▶
Hypokalemia lowers arrhythmia threshold
Target correction to > 4.0 mmol/l for recurrent SVT
Magnesium
▶
Hypomagnesemia associated with arrhythmia susceptibility
Replicate if level low
Calcium
▶
Hypercalcemia or hypocalcemia can promote arrhythmias
Thyroid function
▶
TSH
▶
Hyperthyroidism as reversible trigger
High clinical yield in new-onset SVT without clear cause
Complete blood count
▶
Anemia as high-output trigger
▶
Infection with fever as contributing factor
Cardiac biomarkers
Troponin
▶
Indication when chest pain or concern for ischemia
▶
Mild troponin elevation during SVT in young patients without structural heart disease does not indicate coronary disease
Significant elevation or dynamic rise requires ischemia workup
Sensitive troponin assay preferred in undifferentiated chest pain
BNP or NT-proBNP
▶
Indication when heart failure suspected
▶
Tachycardia-mediated cardiomyopathy concern in prolonged SVT
Guides admission decision in borderline cases
Additional labs
Renal function and BMP
▶
Creatinine for drug dosing decisions
▶
Renal clearance affects sotalol, digoxin dosing
Glucose
▶
Hyperglycemia with stimulant use or stress response
Drug levels when applicable
▶
Digoxin level if on digoxin therapy
▶
Toxicity can precipitate junctional tachycardia mimicking SVT
Theophylline level when relevant
▶
Theophylline toxicity associated with SVT
Diagnostic Tests
Scoring Systems
Risk stratification and classification tools
▶
2015 ACC/AHA/HRS SVT guideline algorithm for narrow QRS tachycardia
▶
Systematic step-by-step approach to differential diagnosis
Distinguishes AVNRT, AVRT, focal atrial tachycardia, sinus tachycardia, atrial flutter
Class I recommendation level
Brugada algorithm for wide-complex tachycardia
▶
Step 1: Absence of RS complex in all precordial leads favors VT
Step 2: RS interval > 100 ms in any precordial lead favors VT
Step 3: AV dissociation favors VT
Step 4: Morphologic criteria in V1 and V6
Vereckei algorithm as alternative to Brugada
▶
aVR lead criteria for VT versus SVT with aberrancy
Initial R wave, notched downstroke, or Vi/Vt ratio favor VT
Limitations of scoring tools
▶
Clinical context and adenosine response may supersede algorithm
Electrophysiology consultation for diagnostic uncertainty
MRI
Cardiac MRI role in SVT workup
▶
Not indicated in acute SVT management
▶
No role in acute rhythm termination or diagnosis
Structural assessment for recurrent or refractory SVT
▶
Myocardial fibrosis or cardiomyopathy as arrhythmia substrate
Congenital heart disease anatomy
Pre-ablation planning in select cases
▶
Anatomic mapping of accessory pathways (limited utility)
Assessment of myocardial function before ablation
CT
CT cardiac role
▶
Coronary CTA when ischemia cannot be excluded
▶
Anginal chest pain in patient with SVT and CAD risk factors
Rule out significant coronary disease if troponin elevated
CT pulmonary angiography when PE mimics SVT
▶
Unexplained sinus tachycardia post SVT conversion
Clinical Wells score to guide decision
CT is not part of routine SVT evaluation
▶
No role in acute rhythm diagnosis
Structural assessment deferred to echocardiography or MRI
Ultrasound
Echocardiography
▶
Transthoracic echocardiography indications
▶
New-onset SVT especially in older patients or those with comorbidities
Assess for structural heart disease, wall motion abnormalities, EF
ACC/AHA/HRS guideline Class I recommendation for new SVT
Findings that alter management
▶
Reduced EF contraindicates verapamil and diltiazem
Significant structural disease shifts toward ablation or specialist care
Point-of-care ultrasound (POCUS)
▶
Bedside cardiac POCUS in hemodynamically unstable SVT
▶
Gross LV function assessment
Pericardial effusion screen
IVC assessment for volume status
Lung POCUS
▶
B-lines indicating pulmonary edema in tachycardia-mediated cardiomyopathy
Pleural effusion in decompensated heart failure
Disposition
Discharge criteria
Copy
Suitable for discharge from ED
▶
Conversion to normal sinus rhythm achieved
▶
Post-conversion ECG reviewed and no delta wave or long QT
Hemodynamically stable throughout and after conversion
▶
SBP >= 90 mmHg
No chest pain or heart failure features
Structural heart disease excluded or known and stable
▶
Known SVT with typical presentation and reliable follow-up
No electrolyte abnormality requiring IV correction
▶
Oral electrolyte replacement at home feasible
Discharge prerequisites
▶
Outpatient cardiology or EP follow-up arranged
▶
Within 1 to 2 weeks for first episode
Ablation discussion arranged for recurrent cases
Avoidance counseling provided
▶
Trigger modification: caffeine, alcohol, stimulants
Admission indications
Admit to telemetry or monitored bed
▶
Failure to convert in ED after appropriate pharmacologic attempts
▶
Repeat episodes during observation period
Hemodynamic instability requiring cardioversion
▶
Even if rhythm restored, monitor for recurrence
Significant troponin elevation or new ECG changes
▶
Ischemia workup required as inpatient
New-onset SVT in patient with known structural heart disease
▶
Cardiology or EP management inpatient
Newly diagnosed pre-excitation syndrome
▶
Risk stratification and ablation planning
ICU or step-down indications
▶
Hemodynamic compromise requiring vasopressors
▶
Tachycardia-mediated cardiomyopathy with acute decompensation
Wide complex tachycardia with ongoing diagnostic uncertainty
▶
Cannot exclude ventricular tachycardia
High-degree block or other arrhythmia complications after adenosine
Follow-up planning
Copy
Outpatient management referrals
▶
Electrophysiology referral for ablation counseling
▶
Curative ablation preferred over lifelong antiarrhythmic therapy
Success rates > 95% for AVNRT and AVRT
Ambulatory monitoring if diagnosis uncertain
▶
Holter monitor 24 to 48 hours for frequent episodes
Patch monitor up to 2 weeks for less frequent episodes
Implantable loop recorder for very infrequent episodes
Treatment
Vagal maneuvers
First-line non-pharmacologic termination
▶
Modified Valsalva maneuver (REVERT technique)
▶
Semi-recumbent position, blow into 10 ml syringe for 15 seconds
Immediately supine with legs raised 45 degrees for 15 seconds
43% conversion rate in REVERT trial (versus 17% standard Valsalva)
Class I recommendation, ACEP Level A evidence
Carotid sinus massage
▶
5 to 10 second firm pressure at carotid bifurcation
Conversion rate 10 to 19%
Contraindicated if carotid bruit present or recent CVA or TIA
Diver's reflex
▶
Ice water facial immersion
Useful in pediatric population
Adenosine
Adenosine IV protocol
▶
First dose 6 mg rapid IV push followed immediately by 20 ml NS flush
▶
Administered in antecubital or proximal IV site
Half-life approximately 10 seconds requires rapid delivery
If no conversion after 1 to 2 minutes, second dose 12 mg IV rapid push
▶
Third dose 12 mg if still no response
Overall conversion rate approximately 90% for AVNRT and AVRT
Diagnostic use in undifferentiated tachycardia
▶
Terminates AVNRT and AVRT
Unmasks flutter waves in atrial flutter without terminating
No effect on VT
Contraindications
▶
Pre-excited AF or suspected WPW with atrial fibrillation
Severe reactive airway disease or asthma
High-degree AV block or sick sinus syndrome without pacemaker
Heart transplant recipients (increased sensitivity, use 1 to 3 mg)
Common transient side effects
▶
Flushing, dyspnea, chest tightness lasting 20 to 30 seconds
Warn patient before administration
Non-dihydropyridine calcium channel blockers
Diltiazem IV
▶
First dose 0.25 mg/kg IV over 2 minutes (typical 15 to 20 mg)
▶
Conversion rate 64 to 98%
Second dose if no response after 15 minutes
▶
0.35 mg/kg IV over 2 minutes (typical 20 to 25 mg)
Maintenance infusion if indicated
▶
5 to 15 mg/hour IV titrated to heart rate
Contraindications
▶
HFrEF (EF < 40%) due to negative inotropic effect
Wide complex tachycardia of uncertain origin
Pre-excited AF or WPW
Severe hypotension
Verapamil IV
▶
Initial dose 5 mg IV over 2 minutes
▶
May repeat 5 to 10 mg IV after 15 to 30 minutes if needed
Total maximum 20 mg
Conversion rate similar to diltiazem 64 to 98%
Contraindications same as diltiazem
▶
HFrEF, wide complex tachycardia of uncertain origin, pre-excited AF
Beta-blockers
IV beta-blockers for SVT
▶
Metoprolol IV
▶
2.5 to 5 mg IV over 2 minutes
May repeat every 5 minutes up to 3 doses (maximum 15 mg)
Useful alternative when diltiazem or verapamil contraindicated
Esmolol IV (ultra-short acting)
▶
Loading dose 500 mcg/kg IV bolus over 1 minute
Maintenance infusion 50 mcg/kg/minute
Titrate by 25 to 50 mcg/kg/minute every 5 to 15 minutes
Maximum 300 mcg/kg/minute
Half-life 9 minutes allows rapid offset if hypotension occurs
Contraindications
▶
Decompensated heart failure
Significant reactive airway disease
Bradycardia or high-degree AV block
Synchronized cardioversion
Electrical cardioversion protocol
▶
Indications
▶
Hemodynamic instability at any time
Failure of pharmacologic cardioversion after two adequate drug attempts
Procedural steps
▶
Procedural sedation with midazolam or propofol when patient conscious
Synchronized mode confirmed on defibrillator before shock delivery
Starting energy 50 to 100 J biphasic
Escalate energy if no conversion: 150 to 200 J
Post-cardioversion
▶
Post-conversion ECG immediately
Monitor for recurrence 30 to 60 minutes
Identify and correct precipitating cause
Etripamil (novel agent)
Etripamil intranasal
▶
FDA-approved for acute termination of PSVT
▶
Intranasal calcium channel blocker
70 mcg per nostril (total 140 mcg) self-administered
Efficacy data
▶
Conversion rate 64% versus 31% placebo at 30 minutes in NODE-301 trial
Median time to conversion 17 minutes
Role in clinical practice
▶
Pill-in-the-pocket equivalent for PSVT
Requires pre-dispensing and patient education
Not a first-line ED option but relevant for outpatient plan
Long-term pharmacologic prophylaxis
Antiarrhythmic agents for prevention
▶
Beta-blockers (first-line for chronic prevention)
▶
Metoprolol succinate 25 to 100 mg orally once daily
Atenolol 25 to 100 mg orally once daily
Non-dihydropyridine CCBs (first-line alternative)
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Diltiazem extended-release 120 to 360 mg orally once daily
Verapamil extended-release 120 to 480 mg orally once daily
Flecainide (pill-in-the-pocket or daily dosing)
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Patients without structural heart disease only
50 to 100 mg orally twice daily
Contraindicated in HFrEF, coronary artery disease
Propafenone (pill-in-the-pocket or daily dosing)
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Patients without structural heart disease only
150 to 300 mg orally twice or three times daily
Class Ic agent; contraindicated in structural heart disease
Ablation preferred over long-term antiarrhythmic therapy for recurrent SVT
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Class I recommendation ACC/AHA/HRS 2015
Special Populations
Pregnancy
SVT in pregnancy
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Physiologic changes increasing susceptibility
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Increased blood volume and cardiac output
Hormonal changes and increased adrenergic tone
SVT prevalence increases with advancing gestation
Vagal maneuvers
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First-line and preferred; safe in all trimesters
Modified Valsalva modified for gravid abdomen positioning
Adenosine in pregnancy
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Generally considered safe for acute termination
Short half-life minimizes fetal exposure
Class B evidence; preferred pharmacologic agent in pregnancy
Drug safety profile
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Metoprolol (FDA category C) acceptable for chronic prevention with monitoring
Verapamil second-line; avoid in first trimester if possible
Flecainide and propafenone limited data; avoid unless refractory
Sotalol acceptable with QTc monitoring
Cardioversion in pregnancy
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Safe at all gestational ages when hemodynamic instability present
Fetal monitoring during and after cardioversion
Fetal effects of rapid maternal heart rate
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Uteroplacental insufficiency risk with prolonged maternal SVT
Maternal hemodynamic stabilization protects fetal circulation
Obstetric consultation for any arrhythmia in pregnancy
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Fetal monitoring when viable gestation
Geriatric
SVT in older adults
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Higher prevalence
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Age > 65 associated with over 5x increased SVT risk
Comorbid structural heart disease more common
Drug considerations in older adults
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Adenosine at standard dose but monitor for prolonged AV block
Diltiazem and verapamil increased hypotension risk
Beta-blockers increased bradycardia and hypotension risk
Renal dosing adjustments for all renally cleared agents
Polypharmacy interactions
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Digoxin and verapamil combination increases digoxin toxicity risk
QT-prolonging drug interactions require review before antiarrhythmic selection
Fall risk during SVT episodes
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Lightheadedness and presyncope heightened risk in older adults
Urgent evaluation and close follow-up
Ablation in older adults
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Ablation safe and effective in older adults
Preferred over long-term antiarrhythmic drugs given toxicity profile
Tachycardia-mediated cardiomyopathy
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Greater risk with chronically elevated heart rate
EF may improve significantly after rhythm control
Pediatrics
SVT in children
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Prevalence
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Most common tachyarrhythmia requiring treatment in pediatric patients
AVRT more common than AVNRT in infants; AVNRT predominates in older children
Presentation differences
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Neonates and infants may present with irritability, poor feeding, or heart failure
Older children report palpitations similar to adults
Vagal maneuvers in pediatrics
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Diver's reflex (ice to face) effective in infants
Valsalva feasible in children able to cooperate
Adenosine dosing in pediatrics
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Initial dose 0.1 mg/kg IV rapid push (maximum 6 mg)
Second dose 0.2 mg/kg IV (maximum 12 mg) if no response
Neonates may be more sensitive; lower initial dose 0.05 mg/kg
Cardioversion in pediatrics
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0.5 to 1 J/kg synchronized; escalate to 2 J/kg if no conversion
Sedation required for conscious pediatric patients
WPW in children
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More common cause of SVT in pediatric age group
High-risk accessory pathway evaluation with EP study
Ablation recommended for symptomatic WPW in children
Long-term management
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Spontaneous resolution of SVT common in neonates by 12 months
Prophylaxis with propranolol or digoxin (infants without WPW) when recurrent
Pediatric cardiology consultation for all new pediatric SVT
Background
Epidemiology
Prevalence and incidence
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Prevalence approximately 2.29 per 1,000 persons in the United States
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Approximately 89,000 new cases per year in the US
SVT subtype distribution
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AVNRT accounts for approximately 60% of PSVT
AVRT accounts for approximately 30% of PSVT
Focal atrial tachycardia accounts for approximately 10% of PSVT
Demographic patterns
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Approximately 50% of patients are aged 45 to 64 years
Female sex associated with 2x increased risk
Age > 65 associated with over 5x increased risk
Lone PSVT without cardiovascular disease
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Accounts for 39% of cases
Younger mean age 37 years
Higher mean rate 186 bpm
Morbidity and mortality
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Generally a benign condition
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Significant symptom burden affecting quality of life
Tachycardia-mediated cardiomyopathy in approximately 1% of untreated PSVT
WPW prevalence in general population
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0.1 to 0.3% of general population
Sudden cardiac death risk in high-risk accessory pathways
Pathophysiology
Reentry mechanisms
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AVNRT mechanism
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Dual AV node physiology with fast and slow pathways
Typical AVNRT: slow anterograde conduction, fast retrograde
Atrial activation nearly simultaneous with ventricular activation
P wave buried in or distorting end of QRS
AVRT mechanism
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Reentrant circuit incorporating accessory pathway and AV node
Orthodromic AVRT: anterograde through AV node, retrograde through accessory pathway
Antidromic AVRT: anterograde through accessory pathway, retrograde through AV node
Antidromic produces wide complex tachycardia
Focal atrial tachycardia mechanism
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Abnormal automaticity or triggered activity from ectopic atrial focus
P wave morphology reflects site of origin
Less responsive to adenosine than reentrant SVT
Triggers and electrophysiologic basis
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Premature atrial or ventricular beats initiate reentry circuit
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Critical conduction velocity differences between fast and slow pathways enable reentry
Electrolyte disturbances increase susceptibility
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Hypokalemia and hypomagnesemia alter conduction velocity
Sympathetic stimulation increases automaticity and conduction speed
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Caffeine, stress, stimulants increase catecholamine levels
Therapeutic Considerations
Evidence base for adenosine
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Conversion rate approximately 90% for AVNRT and AVRT
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Superior to verapamil for speed of action
Class I recommendation ACC/AHA/HRS 2015 guideline
Diagnostic information from adenosine response guides further management
Catheter ablation evidence
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Success rates exceed 95% for AVNRT and AVRT
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Class I recommendation for patients with recurrent symptomatic PSVT who prefer ablation
Major complication rate less than 1% in experienced centers
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AV block risk with AVNRT ablation at fast pathway site
RF or cryotherapy used depending on anatomy and institution
Ablation preferred over lifelong antiarrhythmic therapy in most patients
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Cost-effective strategy for recurrent SVT
Antiarrhythmic drug selection principles
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Avoid class Ic drugs (flecainide, propafenone) in structural heart disease
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CAST trial demonstrated increased mortality in post-MI patients
Non-dihydropyridine CCBs and beta-blockers safest for long-term use in structurally normal heart
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ACC/AHA/HRS Class I recommendation for chronic prevention
Sotalol and amiodarone reserved for refractory cases or structural heart disease
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QTc monitoring required for sotalol
Amiodarone significant toxicity profile limits use for benign SVT
Tachycardia-mediated cardiomyopathy
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Reversible cause of reduced EF
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EF normalizes in majority after arrhythmia control
Diagnosis of exclusion after structural causes ruled out
Expected improvement over weeks to months after rhythm control
Patient Discharge Instructions
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What you were treated for
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Supraventricular tachycardia (SVT)
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A fast heart rhythm starting in the upper chambers of the heart
Usually not dangerous but can cause significant symptoms
What happened in the ED
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Your heart rhythm was treated
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With vagal maneuvers or medication to restore a normal rhythm
Your heart returned to a normal rate
Medications prescribed
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Take all prescribed medications exactly as directed
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Do not stop beta-blockers or calcium channel blockers abruptly
Avoid caffeine, alcohol, and energy drinks
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These are common triggers for SVT recurrence
Avoid recreational stimulants such as cocaine, amphetamines, or MDMA
What to do if SVT returns before your follow-up
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Try the modified Valsalva maneuver
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Blow into a syringe or through closed lips for 15 seconds
Then lie flat and raise legs above heart level for 15 seconds
This may stop the episode
If maneuver does not work, come to the ED
Warning signs to return to the emergency room immediately
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Chest pain or pressure that does not stop
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Especially with new shortness of breath or sweating
Fainting or loss of consciousness
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Syncope during SVT episode
Heart racing that does not stop after vagal maneuvers
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Rate > 150 bpm or lasting more than 15 to 20 minutes
Severe shortness of breath or inability to breathe comfortably at rest
Lips or face turning blue
New confusion or inability to speak normally
Follow-up instructions
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Cardiology or heart rhythm specialist follow-up within 1 to 2 weeks
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Ablation procedure to cure SVT permanently can be discussed
A small camera-equipped catheter treats the abnormal pathway
Wear a heart monitor if prescribed
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Captures future episodes for diagnosis
Avoid driving or operating heavy machinery until seen by follow-up cardiologist
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Especially if episodes cause presyncope or syncope
References
Guidelines and key sources
Major society guidelines
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2015 ACC/AHA/HRS Guideline for the Management of Adult Patients with Supraventricular Tachycardia
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Published in Journal of the American College of Cardiology 2016
Comprehensive algorithm-based management recommendations
ACEP Clinical Policy for Tachyarrhythmias
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Adenosine and cardioversion Level A recommendations
Key trials and studies
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REVERT trial (Appelboam et al., Lancet 2015)
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Modified Valsalva 43% conversion versus 17% standard Valsalva
Established modified Valsalva as preferred vagal maneuver
NODE-301 trial for etripamil
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64% conversion rate versus 31% placebo
FDA-approved intranasal PSVT termination
CAST trial (Cardiac Arrhythmia Suppression Trial)
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Class Ic antiarrhythmics increased mortality post-MI
Basis for contraindication in structural heart disease
Evidence sources for this document
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JAMA 2021 SVT review
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Prevalence 2.29 per 1,000 persons, 89,000 new US cases per year
Symptom prevalence data: palpitations 86%, chest discomfort 47%, dyspnea 38%
Journal of the American College of Cardiology SVT epidemiology data
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Sex and age risk factors
WPW prevalence 0.1 to 0.3%
Coding standards
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ICD-10 I47.1 supraventricular tachycardia
ICD-10 I45.6 Wolff-Parkinson-White syndrome
SNOMED CT paroxysmal supraventricular tachycardia disorder
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.
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Management Protocols
Supraventricular Tachycardia (SVT)