The Role of Coronary Perfusion Changes in Cardiac Dysfunction Associated With Brain Death.

Abstract

Backg round: Previous studies described a hem odynamic insta bility in the pote nt ial orga n don or which has clinical relevance for cardiac t ransplantation. The possible pathophysiological link between altered loadin g conditio ns, coronary perfu sion. and ca rdiac function afte r brain death has not been investiga te d yet. Ther efore this st udy was und ert aken to invest igat e t he ro le of corona ry perfu sion changes durin g brain death in cardiac dysfunction. Methods : Dogs o n card iopulmonary bypass prov ided isovolumetr ic left-ventricular (LV) cont ract ions. By protoco l, coronary perfu sion pressure was kept at th e leve l of mean aort ic pressure. LV pressure, LV dP/dt , the slope of end-systo lic pressure-volume relationship (Em.l K) ' coronary blood flow (CBF), and myocardial oxyge n consumpt ion (MV0 2) were measured. Brain death was induced by a subdurally placed balloon-catheter. Res ults: Induct ion of brain death led to a transient hyperd ynamic response with a significant increase of ao rt ic and LV pressure, dP/dt, Em.l K ' CBF, and MV0 2 • Thereafter, ao rt ic pressure and, parallelly, LV pressure, dP/dt, Em.l K ' CBF, and MV0 2 decreased significantly. However, if coronary perfusion pressure was decoupled from aortic pressure and elevate d to pre-brain death level, CSF and myocardial cont ract ility were restored to baseline level. Concluslon: The impairment of coro nary blood flow may cont ribute to decreased contra ctility afte r brain death.

What can be learned from brain-death models?

“…Contraction band necrosis occurs frequently in individuals who survived for a prolonged period after an intracranial hemorrhage. Recent experimental investigations demonstrated that acute brain death caused by increased intracranial pressure results in a transient increase in myocardial adenosine and lactate, which indicates that oxygen demand exceeds oxygen delivery during the sympathetic storm [36]. In conclusion, in pig brain death models the sympathetic storm produced transient contractile dysfunction, consistent with ischemic injury during brain death [37,38].…”

Improvement of Donor Myocardial Function after Treatment of Autonomic Storm During Brain Death

“…The mechanisms of myocardial damage are related to excessive activation of cardiac sympathetic nervous system. Its neurotransmitters (catecholamines, NPY) either directly or through inadequate coronary blood flow induce myocardial dysfunction (19,20,22,(37)(38)(39)(40)(41)(42)(43).…”

Determinants and prognostic value of ischemic necrosis in early biopsies following heart transplant

“…Although the donor heart is a healthy organ, the influences on cardiovascular function of several neuroendocrine disturbances caused by brain death are still to be fully explained. [18][19][20][21][22][23] Because of organ shortage and the need for emergency operation, the graft is sometimes retrieved from a donor situated over 500 km from the place of implantation, so that the ischemic time period may exceed 3 h. A reliable technique of graft preservation would not only improve early and late results of cardiac transplantation, but also allow for an increased number of transplant procedures.…”