Enhancement of perfusion reserve by cardiac resynchronization therapy.

on larger ASD devices resulting in the appearance of migraine. Indeed, even macro-thrombi seem not to be so uncommon after device closure. Nevertheless, we do agree that (paradoxical) micro-emboli are generally distributed randomly. However, regional differences in cerebral arterial reactivity might be present and explain why diffuse micro-emboli can cause repeated lateralized signs. In addition, it can be hypothesized that micro-emboli do not have to induce brain ischaemia to provoke a migraine attack, but only to modulate the neurovascular vaso-reactivity. Finally, the appearance of migraine is strongly age dependent. Although it is purely hypothetical, it is possible that the interaction between trigger substances and the neurovascular excitability for these trigger substances changes over time. With device closure, we might influence this interaction. The fact that migraine appeared or disappeared almost immediately after ASD closure suggests a causative relationship. However, a larger study sample in a controlled prospective study design will be necessary to answer the remaining questions.