Acute Heart Failure, 90-Day Mortality, and Gravitational Ischemia in the Brain

Abstract

During the 90 days following hospitalization for acute heart failure, the ejection fraction and type of discharge medications have been shown in clinical trials to have little effect on mortality. We examined the recent literature addressing brain-related etiologies of sudden death following heart failure. Two mechanisms of sudden unexpected death have been suggested to possibly result from four significant influences on pathophysiology in the brain. The two causes of sudden death are (1) severe cardiac arrhythmia and (2) neurogenic pulmonary edema. They are both mediated through the brainstem autonomic nuclei generally and executed specifically through the dorsal motor nucleus of the vagus nerve. The four significant influences on pathophysiology, all contributing to ischemia in the brainstem autonomic nuclei, are: (1) Hyper-stimulation of neurons in the solitary tract nucleus, increasing their metabolic requirements; (2) Inadequate blood flow at a vascular watershed terminus, perfusing the autonomic nuclei; (3) Additionally decreased blood flow, globally throughout the brain, following vasoconstriction related to relative hyperventilation and decreased pCO2 levels; (4) Gravitational ischemia in the brainstem caused by the weight of the cerebral hemispheres sitting above the brainstem. Changes in head tilt release gravitational ischemia in the brain. There is no specific head position relative to gravity that is considered favorable or unfavorable for an extended period of time, longer than 24 h. Even a small degree of head elevation, used in managing pulmonary congestion, may increase gravitational ischemia in the posterior fossa and brainstem. In this paper, we suggest a new and important research avenue for intervening in cardiac arrhythmias and preventing their occurrence through the non-invasive use of head-tilting and other head repositioning maneuvers. This could potentially help many geriatric patients with heart failure, who have decreased mobility in bed, and who tend to stay in one position longer, thereby increasing gravitational ischemia in the brain.

Late seizures following cerebral venous thrombosis—may be a maladaptive attempt to release gravitational ischemia in the brain

“…In conclusion, the CVT Late Seizure Investigators [1] reported important findings from their systematic review, which were potentially consistent with the findings of other recent papers [2][3][4][5] to the extent of supporting further research into a possible relationship between late seizures following CVT, cerebro-vascular inflammatory mechanisms, and gravity in the brain.…”

“…The CVT Late Seizure Investigators concluded, in part, that further high-quality studies are warranted to develop predictive models for individualized risk stratification and prediction of CVT late seizures [1]. However, the overall literature about CVT suggests that important resources in that regard may include autopsy studies [2], combined with studies of systemic biological markers [3], and observations about gravity in the brain [4,5].…”

“…The CVT Autopsy Investigators [2] suggested that intramural venous inflammation may potentially persist to cause endothelitis, with endothelial dysfunction. Others [4,5] have observed that this may result in difficulty with transmural venous fluid movement and with release of gravitational ischemia in the brain. CVT may therefore cause both immediate and long-term difficulty with release of gravitational ischemia in the brain.…”

“…Gravitational ischemia in the brain results from the mass effect of one part of the brain upon another in a gravitational field [4,5]. In any given head position, the top half of the brain (farthest from the center of the earth) is sitting on the bottom half as a weight-burden.…”

“…Ischemia, which may form on the bottom layers, is reversible in its early stages. Gravitational ischemia in the brain may potentially be largely preventable by frequently changing the head tilt-just as ischemic skin breakdown, bed sores, and decubitus ulcers are currently prevented by frequent changes in general body positioning, focused on the effects of gravity [4,5].…”