Cardiac arrest at induction of anesthesia in a child with undiagnosed right-ventricular dependent coronary circulation: a case report

Pediatric perioperative cardiac arrest occurs in 1.4 per 10,000 anesthetics, with an overall mortality rate of 26%. The etiology of the arrest is identifiable in the majority of these patients. We report the case of a child with a complex congenital heart defect, who sustained a cardiac arrest at induction of anesthesia, secondary to right-ventricular dependent coronary circulation. We discuss the incidence, risks, anesthetic management and outcomes of pediatric cardiac arrest in the perioperative period especially in patients with complex congenital heart disease.

Proteasome activation as a critical event of thymocyte apoptosis

Caspase activation may occur in a direct fashion as a result of CD95 death receptor crosslinking (exogenous pathway) or may be triggered indirectly, via a Bcl-2 inhibitable mitochondrial permeabilization event (endogenous pathway). Thymocyte apoptosis is generally accompanied by proteasome activation. If death is induced by DNA damage, inactivation of p53, overexpression of a Bcl-2 transgene, inhibition of protein synthesis, and antioxidants (N-acetylcyteine, catalase) prevent proteasome activation. Glucocorticoid-induced proteasome activation follows a similar pattern of inhibition except for p53. Caspase inhibition fails to affect proteasome activation induced by topoisomerase inhibition or glucocorticoid receptor ligation. In contrast, caspase activation (but not p53 knockout or Bcl-2 overexpression) does interfere with proteasome activation induced by CD95. Specific inhibition of proteasomes with lactacystin or MG123 blocks caspase activation at a pre-mitochondrial level if thymocyte apoptosis is induced by DNA damage or glucocorticoids. In strict contrast, proteasome inhibition has no inhibitory effect on the mitochondrial and nuclear phases of apoptosis induced via CD95. Thus, proteasome activation is a critical event of thymocyte apoptosis stimulated via the endogenous pathway yet dispensable for CD95-triggered death.