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Indications And Usage Verapamil Is Indicated For The Treatment Of Supraventricular Tachyarrhythmias, Including: • Rapid Conversion To Sinus Rhythm Of Paroxysmal Supraventricular Tachycardias, Including Those Associated With Accessory Bypass Tracts (Wolff-Parkinson-White [Wpw] And Lown-Ganong-Levine [Lgl] Syndromes). When Clinically Advisable, Appropriate Vagal Maneuvers (E.g., Valsalva Maneuver) Should Be Attempted Prior To Verapamil Administration. • Temporary Control Of Rapid Ventricular Rate In Atrial Flutter Or Atrial Fibrillation, Except When The Atrial Flutter And/or Atrial Fibrillation Are Associated With Accessory Bypass Tracts (Wolff-Parkinson-White [Wpw] And Lown-Ganong-Levine [Lgl] Syndromes). In Controlled Studies In The U.s., About 60% Of Patients With Supraventricular Tachycardia Converted To Normal Sinus Rhythm Within 10 Minutes After Intravenous Verapamil Hydrochloride. Uncontrolled Studies Reported In The World Literature Describe A Conversion Rate Of About 80%. About 70% Of Patients With Atrial Flutter And/or Fibrillation With A Fast Ventricular Rate Respond With A Decrease In Heart Rate Of At Least 20%. Conversion Of Atrial Flutter Or Fibrillation To Sinus Rhythm Is Uncommon (About 10%) After Verapamil Hydrochloride And May Reflect The Spontaneous Conversion Rate, Since The Conversion Rate After Placebo Was Similar. The Effect Of A Single Injection Lasts For 30–60 Minutes When Conversion To Sinus Rhythm Does Not Occur. Because A Small Fraction (<1.0%) Of Patients Treated With Verapamil Hydrochloride Respond With Life-Threatening Adverse Responses (Rapid Ventricular Rate In Atrial Flutter/fibrillation With An Accessory Bypass Tract, Marked Hypotension, Or Extreme Bradycardia/asystole—see Contraindications And Warnings ), The Initial Use Of Intravenous Verapamil Hydrochloride Should, If Possible, Be In A Treatment Setting With Monitoring And Resuscitation Facilities, Including Dc-Cardioversion Capability (See Suggested Treatment Of Acute Cardiovascular Adverse Reactions ) . As Familiarity With The Patient’s Response Is Gained, An Office Setting May Be Acceptable. Cardioversion Has Been Used Safely And Effectively After Intravenous Verapamil.
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