Update on transient cardiac standstill in cerebrovascular surgery
Circulatory Arrest, Deep Hypothermia Induced
Vascular System Injuries
Transient cardiac standstill is a complementary procedure used with microsurgery to treat patients with particularly complex aneurysms, such as large or giant cerebral aneurysms. These procedures allow the aneurysms to be decompressed while maintaining a bloodless field and increased surgical exposure. Deep hypothermia combined with circulatory arrest provides cerebroprotection with optimal surgical conditions. However, its disadvantage is the relatively high risk of the procedure, which requires extensive expertise and infrastructure. Thus, its use is typically limited to patients with complex posterior circulation aneurysms. Adenosine-induced transient asystole is an easily applied technique in a variety of clinical situations. Its use requires minimal advanced preparation and no complex logistical coordination with other subspecialties. However, patient-specific dose-response relationships must be determined by exposure, so the relationship may not be known in an emergent situation. Persistent hypotension is a potentially major complication. Rapid ventricular pacing (RVP) has recently been reintroduced into cerebrovascular surgery. It is more predictable than adenosine in response time and, thus, can be used during unanticipated complications, such as aneurysmal rupture. It also induces a shorter period of hypotension compared with adenosine. However, RVP is more invasive and more complex from an anesthesia standpoint. Vascular neurosurgeons should be familiar with these techniques and know their applications and limitations.