Advances in anesthetic and surgical management, such as induced deep hypothermic circulatory arrest and application of temporary clips, have improved outcome for patients with basilar artery aneurysms. Nonetheless, these techniques are associated with significant risks. The authors report a case in which three transient periods of cardiac asystole were induced during basilar artery aneurysm surgery. Adenosine-induced asystole facilitated the safe clipping of the aneurysm by producing consistent periods of profound hypotension and collapse of the aneurysm without the need for temporary clipping. This technique provided unencumbered identification of perforating arteries, precise definition of the local anatomy, and an ideal environment for the safe placement of the aneurysm clip.

Objectives: We investigated the relationship between low wall shear stress (WSS) and severe endothelial dysfunction (EDFx). Background: Local hemodynamic forces, such as WSS play an important role in atherogenesis through their effect on endothelial cells. We hypothesized that low WSS independently predicts severe EDFx in patients with coronary artery disease (CAD). Methods: Forty-four patients with CAD underwent coronary angiography, fractional flow reserve (FFR) and endothelial function testing. Segments with >10% vasoconstriction after acetylcholine (Ach) infusion were defined as having severe EDFx. WSS, calculated using 3D angiography, velocity measurements and computational fluid dynamics, was defined as low (< 1 Pa), intermediate (1–2.5 Pa) or high (> 2.5 Pa). Results: Median age was 52 years, 73% were females. Mean FFR was 0.94 ± 0.06. In 4,510 coronary segments, median WSS was 3.67 Pa. 24% had severe EDFx. A higher proportion of segments with low WSS had severe EDFx (71%) compared to intermediate WSS (22%) or high WSS (23%) (p < 0.001). Segments with low WSS demonstrated greater vasoconstriction in response to ACh than intermediate or high WSS segments (−10.7% vs. −2.5% vs. +1.3%, respectively, p < 0.001). In a multivariable logistic regression analysis, female sex (OR: 2.44, p = 0.04), diabetes (OR: 5.01, p = 0.007) and low WSS (OR: 9.14, p < 0.001) were independent predictors of severe EDFx. Conclusion: In patients with non-obstructive CAD, segments with low WSS demonstrated more vasoconstriction in response to ACh than intermediate or high WSS segments. Low WSS was independently associated with severe endothelial dysfunction.

The NMDA receptor-mediated Ca2+ signaling during simultaneous pre- and postsynaptic activity is critically involved in synaptic plasticity and thus has a key role in the nervous system. In GRIN2-variant patients alterations of this coincidence detection provoked complex clinical phenotypes, ranging from reduced muscle strength to epileptic seizures and intellectual disability. By using our gene-targeted mouse line (Grin2aN615S), we show that voltage-independent glutamate-gated signaling of GluN2A-containing NMDA receptors is associated with NMDAR-dependent audiogenic seizures due to hyperexcitable midbrain circuits. In contrast, the NMDAR antagonist MK-801-induced c-Fos expression is reduced in the hippocampus. Likewise, the synchronization of theta- and gamma oscillatory activity is lowered during exploration, demonstrating reduced hippocampal activity. This is associated with exploratory hyperactivity and aberrantly increased and dysregulated levels of attention that can interfere with associative learning, in particular when relevant cues and reward outcomes are disconnected in space and time. Together, our findings provide (i) experimental evidence that the inherent voltage-dependent Ca2+ signaling of NMDA receptors is essential for maintaining appropriate responses to sensory stimuli and (ii) a mechanistic explanation for the neurological manifestations seen in the NMDAR-related human disorders with GRIN2 variant-meidiated intellectual disability and focal epilepsy.