Maintenance of pig brain function under extracorporeal pulsatile circulatory control (EPCC).

Selective vascular access to the brain is desirable in metabolic tracer, pharmacological and other studies aimed to characterize neural properties in isolation from somatic influences from chest, abdomen or limbs. However, current methods for artificial control of cerebral circulation can abolish pulsatility-dependent vascular signaling or neural network phenomena such as the electrocorticogram even while preserving individual neuronal activity. Thus, we set out to mechanically render cerebral hemodynamics fully regulable to replicate or modify native pig brain perfusion. To this end, blood flow to the head was surgically separated from the systemic circulation and full extracorporeal pulsatile circulatory control (EPCC) was delivered via a modified aorta or brachiocephalic artery. This control relied on a computerized algorithm that maintained, for several hours, blood pressure, flow and pulsatility at near-native values individually measured before EPCC. Continuous electrocorticography and brain depth electrode recordings were used to evaluate brain activity relative to the standard offered by awake human electrocorticography. Under EPCC, this activity remained unaltered or minimally perturbed compared to the native circulation state, as did cerebral oxygenation, pressure, temperature and microscopic structure. Thus, our approach enables the study of neural activity and its circulatory manipulation in independence of most of the rest of the organism.

Hypothermic circulatory arrest for repair of injuries of the thoracic aorta and great vessels.

Traumatic great vessel injuries are frequently lethal events. Expedient diagnosis and prompt repair by clamping and replacing the affected segment of aorta (often with left-heart bypass) can salvage many patients. Rarely, due to the location of the injury or delayed presentation, standard techniques cannot be used and hypothermic circulatory arrest (HCA) is required for access, exposure and repair. The results of surgical reconstruction of acute and chronic traumatic thoracic vascular injuries under these circumstances are not well described. We reviewed all operations on the great vessels at our institution over a 16-year period that had a traumatic etiology and used HCA. Fourteen cases were identified (10 male, 4 female, age 46+/-4 years), arising from three acute and eleven remote traumatic events. All repairs were performed with cardiopulmonary bypass (mean CPB time was 155+/-13 min), deep hypothermia, and an interval of circulatory arrest (mean circulatory arrest interval 31+/-4 min). One patient died in the perioperative period from a stroke (7% 30-day mortality). Another patient exsanguinated from a recurrent pseudoaneurysm 3 months post-repair. No patient developed paraplegia. HCA can be a useful adjunct in managing complex post-traumatic great vessel injuries. Acute injuries of the ascending aorta and transverse arch usually require this technique, but HCA also offers a safe way to manage repair of the descending thoracic aorta when proximal aortic control is compromised.