Introduction

  • SVT indicates tachycardia with atrial rates >100 beats per minute a. Traditionally excludes ventricular tachycardias and atrial fibrillation (AF)

    • b. Includes: atrial tachycardias, atrioventricular (AV) junctional tachycardias, and AV reentrant

    tachycardias

  • Immediate direct-current (DC) cardioversion is indicated in hemodynamically unstable patients
  • More options available for management of hemodynamically stable patients in SVT of unknown etiology a. First-line: vagal maneuvers i. Valsalva maneuver or carotid sinus massage b. Second-line (strength of recommendation varies by ACC and ESC)

    • i. Adenosine

    ii. IV non-dihydropyridine calcium channel blockers (i.e. diltiazem or verapamil)

    iii. IV beta-blockers (i.e. esmolol or metoprolol)

Clinical Detail

AdenosineDiltiazemVerapamil
Dose6 mg x 1
o Repeat 12mg q1-2min x2 if no effect

Can use an initial 12 mg dose if caffeine ingested within 4 hours		0.25mg/kg
o Repeat with 0.35 mg/kg IV in 15 minutes if needed		2.5 to 5 mg
o Repeat with 5-10 mg IV every 15-30 minutes
AdministrationIV bolus as proximal to heart as possible with stopcock or diluted in 20-30 ml normal salineSlow IV push over 2-5 mins
PKOnset: 20-30 sec
Duration: 10-20 sec		Onset: ~3 min
Duration: 3-4 hours		Onset: 2-7 min
Duration: 2-5 hours
Adverse EffectsDyspnea, chest tightness, dizziness, headache, facial flushing, nausea, "electric shock" sensation, transient AV blockHypotension, worsening heart failure, bronchospasm, bradycardia, Caution in >1st degree AV block or SA node dysfunction
Mechanism of ActionSlows conduction through the AV node through a different mechanism, binding to A1 receptors,Inhibits calcium ion from entering slow channels or select voltage-sensitive areas of vascular smooth muscle and myocardium during depolarization
Conversion Rate87-92%86~98%
CautionContraindicated in preexcitation rhythms such as Wolff-Parkinson-White syndrome (WPW)
CommentsPEARL: Draw up adenosine dose in 20 mL syringe then qs to 20 mL with normal saline and use to IV fast push5PEARL: Administering 1-2 grams of calcium gluconate prior to diltiazem administration may limit hypotension

Evidence

Author, yearDesign/sample sizeIntervention & ComparisonOutcome
Sternbach et al. 1986Observational; n=11IV diltiazem 0.25 mg/kg over 5 minConversion in 64% patients
Significant ↓ in HR and ↓ SBP of 12.4 mmHg
McCabe et al. 1991Observational; n=37IV adenosine 6 mg rapid push then 12 mg q2 min x2 if no effect88% conversion in patients with SVT
Hood et al. 1992Prospective, crossover, RCT; n=25I1 = IV adenosine administered in rapid 40 mcg/kg increments q2 min up to 20 mg
I2 = IV verapamil at 70 mcg/kg administered over 5 min and repeated q5 min up to 15 mg		No significant difference in conversion
↑ SBP after conversion with adenosine
No change in mean SBP after conversion with verapamil
Gauche et al. 1994Observational; n=129IV adenosine 12 mg rapid push, repeated x1 after 2 min if no effect85% conversion with the first dose
31% conversion with the second dose
24% of patients appeared in severe distress after administration
Lim et al. 2002Prospective, RCT; n=184IV verapamil 1 mg/min up to 20 mg
Vs.
IV diltiazem 2.5 mg/min up to 50 mg		98.8% conversion rate for verapamil
96.3% conversion rate for diltiazem
No significant differences in success rate
Lim et al. 2009Prospective, RCT; n=206I = either IV verapamil 1 mg/min up to 20 mg or IV diltiazem 2.5 mg/min up to 50 mg toal
C = IV adenosine 6 mg followed by 12 mg if needed		↑ conversion rate with CCBs (98% vs. 86.5%)
1 patient developed hypotension with CCBs,
Mean SBP drop of 13 mmHg with verapamil and 7 mmHg with diltiazem
Alabed et al. 2017Cochrane review; n=622Adenosine vs CCBs at variable dosesNo significant difference in conversion rate (89.7% vs. 92.9%)
1 reported case of hypotension CCB group not requiring treatment

Conclusions

patients. The decrease in systolic blood pressure may not be much of a concern if patients are normotensive. There is

not enough evidence to recommend one agent over in the absence of contraindications to either age

References

  • Brugada et al. European Heart Journal. 2019;00:1-66
  • Page et al. Circulation. 2015;133:506-74
  • Adenosine [Lexi-drugs]
  • Diltiazem [Lexi-drugs]
  • McDowell et al. Acad Emerg Med. 2020;27(1):61-3
  • Sternbach et al. Clin Cardiol. 1986;9:145-49
  • McCabe et al. Ann Emerg Med. 1992;21(4):358-61
  • Hood et al. American Heart Journal. 1992;123:1543-49
  • Gausche et al. Ann Emerg Med. 1994;24(2):183-89
  • Lim et al. Resuscitation. 2002;52:167-74
  • Lim et al. Resuscitation. 2009;80:523-28
  • Alabed et al. Cochrane Database. 2017;10:1-36
Tags:SVT adenosine diltiazem verapamil