A nurse is preparing to administer IV adenosine to a client. Which of the following effects should the nurse anticipate?

A. Loss of consciousness: Adenosine can cause transient lightheadedness or dizziness, but complete loss of consciousness is not an expected effect during administration. Any syncope would be brief and uncommon. B. Conversion of atrial fibrillation: Adenosine is effective for terminating paroxysmal supraventricular tachycardia (PSVT) but does not convert atrial fibrillation or atrial flutter. Its action is specific to AV node–dependent reentrant tachycardias. C. Increased heart rate: Adenosine typically slows conduction through the AV node and may transiently slow the heart rate. An increase in heart rate is not an expected pharmacologic effect. D. A period of asystole: Adenosine briefly blocks AV nodal conduction, which can result in a transient period of asystole lasting a few seconds. This effect is anticipated and resolves quickly, restoring normal sinus rhythm in PSVT.