What should be avoided when treating SVT in patients with a history of WPW or heart transplant?

When treating patients with supraventricular tachycardia (SVT) who have a history of Wolff-Parkinson-White (WPW) syndrome or have undergone a heart transplant, it is crucial to avoid administering adenosine. This is because adenosine can temporarily block conduction through the atrioventricular (AV) node, which may not be effective in patients with WPW due to the presence of an accessory pathway. In such cases, adenosine can potentially lead to an increase in the heart rate or the initiation of more dangerous arrhythmias, as the accessory pathway may bypass the normal conduction pathways.

Patients with a heart transplant often have altered cardiac conduction due to the differences in innervation, and the use of adenosine may not have the desired effect in such individuals. Therefore, when considering the treatment options, it is critical to identify and avoid interventions that could exacerbate the patient's condition or lead to serious complications, making avoidance of adenosine a necessary consideration in these scenarios.