Introduction
- SVT indicates tachycardia with atrial rates >100 beats per minute
- Traditionally excludes ventricular tachycardias and atrial fibrillation (AF)
- 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)
Pharmacology 1-4 | |||
Adenosine | Diltiazem | Verapamil | |
Dose | 6 mg x 1 o Repeat 12mg q1-2min x2 if no effect Can use an initial 12 mg dose of 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 510 mg IV every 15-30 minutes |
Administration | IV bolus as proximal to heart as possible with stopcock or diluted in 20- 30 ml normal saline | Slow IV push over 2-5 mins | |
PK | Onset: 20-30 sec Duration: 10-20 sec | Onset: ~3 min Duration: 3-4 hours | Onset: 2-7 min Duration: 2-5 hours |
Adverse Effects | Dyspnea, chest tightness, dizziness, headache, facial flushing, nausea, “electric shock” sensation, transient AV block | Hypotension, worsening heart failure, bronchospasm, bradycardia, Caution in >1st degree AV block or SA node dysfunction | |
Mechanism of Action | Slows 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 Rate | 87-92% | 86~98% | |
Caution | Contraindicated in preexcitation rhythms such as Wolff-Parkinson-White syndrome (WPW) | ||
Comments | PEARL: Draw up adenosine dose in 20 mL syringe then qs to 20 mL with normal saline and use to IV fast push5 | PEARL: Administering 1-2 grams of calcium gluconate prior to diltiazem administration may limit hypotension |
Jlpruitt@gmh.edu For educational purposes only
Overview of Evidence | |||
Author, year | Design/ sample size | Intervention & Comparison | Outcome |
Sternbach et al. 1986 | Observational; n=11 | IV diltiazem 0.25 mg/kg over 5 min | Conversion in 64% patients Significant ↓ in HR and ↓ SBP of 12.4 mmHg |
McCabe et al. 1991 | Observational; n=37 | IV adenosine 6 mg rapid push then 12 mg q2 min x2 if no effect | • 88% conversion in patients with SVT |
Hood et al. 1992 | Prospective, crossover, RCT; n=25 | I1 = 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. 1994 | Observational; n=129 | IV adenosine 12 mg rapid push, repeated x1 after 2 min if no effect | 85% conversion with the first dose 31% conversion with the second dose 24% of patients appeared in severe distress after administration |
Lim et al. 2002 | Prospective, RCT; n=184 | IV 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 diltiazemNo significant differences in success rate |
Lim et al. 2009 | Prospective, RCT; n=206 | I = 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. 2017 | Cochrane review; n=622 | Adenosine vs CCBs at variable doses | No significant difference in conversion rate (89.7% vs. 92.9%) 1 reported case of hypotension CCB group not requiring treatment |
Conclusions: Diltiazem may be as effective as adenosine in terminating SVT and may be better tolerated by 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