Calcium channel blockers such as verapamil or diltiazem can be used acutely to terminate SVT and chronically to prevent recurrence, but they may cause hypotension. Which statement best describes their use?

Calcium channel blockers such as verapamil or diltiazem can be used acutely to terminate SVT and chronically to prevent recurrence, but they may cause hypotension. Which statement best describes their use?

• A. They can terminate acutely but may cause hypotension
• B. They are never effective in terminating SVT
• C. They are first-line for unstable patients
• D. They have no role in rate control

Answer: (B)

Calcium channel blockers like verapamil and diltiazem terminate SVT acutely by slowing conduction through the AV node, which can interrupt AV-nodal dependent reentry. They also can be used chronically to prevent recurrence by controlling the ventricular rate. However, they can cause hypotension due to vasodilation and negative inotropy, so they are typically used in hemodynamically stable SVT and avoided in unstable patients. The notion that they are never effective in terminating SVT is incorrect because AV-nodal dependent tachycardias (such as AVNRT or AVRT) can terminate with AV nodal blockade. Thus, a concise, accurate description is that they can terminate acutely but may cause hypotension.

Calcium channel blockers like verapamil and diltiazem terminate SVT acutely by slowing conduction through the AV node, which can interrupt AV-nodal dependent reentry. They also can be used chronically to prevent recurrence by controlling the ventricular rate. However, they can cause hypotension due to vasodilation and negative inotropy, so they are typically used in hemodynamically stable SVT and avoided in unstable patients. The notion that they are never effective in terminating SVT is incorrect because AV-nodal dependent tachycardias (such as AVNRT or AVRT) can terminate with AV nodal blockade. Thus, a concise, accurate description is that they can terminate acutely but may cause hypotension.