Computational modeling of heart failure in microgravity transitions.

The space tourism industry is growing due to advances in rocket technology. Privatised space travel exposes non-professional astronauts with health profiles comprising underlying conditions to microgravity. Prior research has typically focused on the effects of microgravity on human physiology in healthy astronauts, and little is known how the effects of microgravity may play out in the pathophysiology of underlying medical conditions, such as heart failure. This study used an established, controlled lumped mathematical model of the cardiopulmonary system to simulate the effects of entry into microgravity in the setting of heart failure with both, reduced and preserved ejection fraction. We find that exposure to microgravity eventuates an increased cardiac output, and in patients with heart failure there is an unwanted increase in left atrial pressure, indicating an elevated risk for development of pulmonary oedema. This model gives insight into the risks of space flight for people with heart failure, and the impact this may have on mission success in space tourism.

Focal stimulation of the sheep motor cortex with a chronically implanted minimally invasive electrode array mounted on an endovascular stent.

Direct electrical stimulation of the brain can alleviate symptoms associated with Parkinson's disease, depression, epilepsy and other neurological disorders. However, access to the brain requires invasive procedures, such as the removal of a portion of the skull or the drilling of a burr hole. Also, electrode implantation into tissue can cause inflammatory tissue responses and brain trauma, and lead to device failure. Here, we report the development and application of a chronically implanted platinum electrode array mounted on a nitinol endovascular stent for the localized stimulation of cortical tissue from within a blood vessel. Following percutaneous angiographic implantation of the device in sheep, we observed stimulation-induced responses of the facial muscles and limbs of the animals, similar to those evoked by electrodes implanted via invasive surgery. Proximity of the electrode to the motor cortex, yet not its orientation, was integral to achieving reliable responses from discrete neuronal populations. The minimally invasive endovascular surgical approach offered by the stent-mounted electrode array might enable safe and efficacious stimulation of focal regions in the brain.