Final answer:
Adenosine, beta blockers, or calcium channel blockers are established treatments for stable regular, narrow complex tachyarrhythmias. If these are ineffective and symptoms are severe, cardioversion or defibrillation may be required.
Step-by-step explanation:
For a relatively stable regular, narrow complex tachyarrhythmia, medications such as adenosine, beta blockers, or calcium channel blockers should be given. These drugs can help to slow down the heart rate and stabilize the rhythm. If a patient is not responding to these medications and is experiencing severe symptoms, more urgent treatment may be necessary, such as a controlled electric shock through cardioversion or defibrillation. Anticoagulants or blood thinners might also be used to reduce the risk of complications associated with arrhythmias.