Cardiovascular Disorders

Hamilton, Douglas R.

doi:10.1007/978-0-387-68164-1_16

Cited by 16 publications

(8 citation statements)

References 274 publications

(338 reference statements)

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“…So, even though the baroreflex ability to accelerate heart rate during orthostasis is maintained efficient during and immediately following spaceflight, astronauts following flight are still prone to fainting. Countermeasures are constantly being operationally implemented to mitigate it immediately following landing . They currently consist of a combination of (a) oral water and salt intake at the end of the flights just before landing, (b) an elastic pressure garment tightly fit to the lower parts of the body with increased compression pressures from abdomen to ankles to counteract the post‐landing gravitationally induced intravascular hydrostatic pressure gradients when upright and finally (c) in some astronauts an iv infusion of isotonic saline immediately following landing .…”

Section: Baroreflexesmentioning

confidence: 99%

“…Countermeasures are constantly being operationally implemented to mitigate it immediately following landing . They currently consist of a combination of (a) oral water and salt intake at the end of the flights just before landing, (b) an elastic pressure garment tightly fit to the lower parts of the body with increased compression pressures from abdomen to ankles to counteract the post‐landing gravitationally induced intravascular hydrostatic pressure gradients when upright and finally (c) in some astronauts an iv infusion of isotonic saline immediately following landing . Since these countermeasures in general seem effective, this demonstrates a deficiency of the cardiovascular control systems per se to maintain an adequate blood pressure.…”

Section: Baroreflexesmentioning

confidence: 99%

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Adaptation of the cardiovascular system to weightlessness: Surprises, paradoxes and implications for deep space missions

Norsk

2020

Acta Physiologica

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Weightlessness in space induces a fluid shift from the dependent to the cephalad parts of the body leading to distension of the cardiac chambers and an accumulation of blood in the veins of the head and neck. Surprisingly, central venous pressure (CVP) during the initial hours of spaceflight decreases compared to being horizontal supine on the ground. The explanation is that the thorax is expanded by weightlessness leading to a decrease in inter‐pleural pressure (IPP), which exceeds the measured decrease in CVP. Thus, transmural CVP (TCVP = CVP − IPP) is increased indicating an augmented cardiac preload. Simultaneously, stroke volume and cardiac output (CO) are increased by 18%‐26% within the initial weeks and more so by 35%‐56% during the subsequent months of flight relative to in the upright posture on the ground. Mean arterial pressure (MAP) is decreased indicating a lower systemic vascular resistance (MAP/CO). It is therefore a surprise that sympathetic nerve activity is not suppressed in space and thus cannot be a mechanism for the systemic vasodilation, which still needs to be explored. Recent observations indicate that the fluid shift during long duration (months) flights is associated with increased retinal thickness that sometimes leads to optical disc oedema. Ocular and cerebral structural changes, increases in left atrial size and decreased flows with thrombi formation in the left internal jugular vein have also been observed. This is of concern for future long duration deep space missions because the health implications are unknown.

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Section: Baroreflexesmentioning

confidence: 99%

Section: Baroreflexesmentioning

confidence: 99%

Adaptation of the cardiovascular system to weightlessness: Surprises, paradoxes and implications for deep space missions

Norsk

2020

Acta Physiologica

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“…Returning to normal gravity on Earth has many important effects, including increased heart rate, decreased vasoconstriction (increased venous pooling), a reduction in exercise capacity (as quantified by heart rate responses and oxygen consumption during specified work loads, Hamilton, 2008 ), and decreased orthostatic tolerance (Buckey et al, 1996 ). Orthostatic intolerance involves exaggerated increase of heart rate, fatigue, light-headedness, dizziness, impairment of performing physical and mental tasks, and often leads to syncope during upright posture.…”

Section: Spaceflight Induced Physiological Effectsmentioning

confidence: 99%

Falls and Fall-Prevention in Older Persons: Geriatrics Meets Spaceflight!

Goswami

2017

Front. Physiol.

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This paper provides a general overview of key physiological consequences of microgravity experienced during spaceflight and of important parallels and connections to the physiology of aging. Microgravity during spaceflight influences cardiovascular function, cerebral autoregulation, musculoskeletal, and sensorimotor system performance. A great deal of research has been carried out to understand these influences and to provide countermeasures to reduce the observed negative consequences of microgravity on physiological function. Such research can inform and be informed by research related to physiological changes and the deterioration of physiological function due to aging. For example, head-down bedrest is used as a model to study effects of spaceflight deconditioning due to reduced gravity. As hospitalized older persons spend up to 80% of their time in bed, the deconditioning effects of bedrest confinement on physiological functions and parallels with spaceflight deconditioning can be exploited to understand and combat both variations of deconditioning. Deconditioning due to bed confinement in older persons can contribute to a downward spiral of increasing frailty, orthostatic intolerance, falls, and fall-related injury. As astronauts in space spend substantial amounts of time carrying out exercise training to counteract the microgravity-induced deconditioning and to counteract orthostatic intolerance on return to Earth, it is logical to suggest some of these interventions for bed-confined older persons. Synthesizing knowledge regarding deconditioning due to reduced gravitational stress in space and deconditioning during bed confinement allows for a more comprehensive approach that can incorporate aspects such as (mal-) nutrition, muscle strength and function, cardiovascular (de-) conditioning, and cardio-postural interactions. The impact of such integration can provide new insights and lead to methods of value for both space medicine and geriatrics (Geriatrics meets spaceflight!). In particular, such integration can lead to procedures that address the morbidity and the mortality associated with bedrest immobilization and in the rising health care costs associated with an aging population demographic.

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“…Maldevelopment anomalies of the vertebral arteries have embryological basis and may be due to the unusual paths in the primitive vascular plexus, persistence of vessels normally obliterated, disappearance of vessels normally retained or due to incomplete development, fusions and absorption of parts usually distinct [9]. Genetic factors and local hemodynamics influence the establishment of final pattern of the artery [10].…”

Section: Methodsmentioning

confidence: 99%

Bilateral Variation in the Course of Vertebral Artery

Kardile¹,

Ughade²

2017

IJAR

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The vertebral artery arises from the first part of subclavian artery and courses within the bony canals of the cervical vertebrae, and then it lies on the upper surface of the posterior arch of the atlas before piercing the dura to enter the cranium. The intracranial part of the vertebral arteries unites at the caudal border of the pons to form the basilar artery. Vertebral artery contributes in supplying posterior part of the brain. In the present case, both the vertebral arteries had normal origin from the first part of subclavian artery. However, the cervical part of the right vertebral artery ascended through the transverse foramina of seventh cervical vertebrae and the left vertebral artery ascended through foramina of fifth cervical vertebrae. Incomplete knowledge of variations of the vertebral artery may lead to serious implications during surgical procedures such as transpedicular fixation technique which is safely performed at the seventh cervical vertebra, in which the vertebral artery is not usually present at the transverse foramen.

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Cardiovascular Disorders

Cited by 16 publications

References 274 publications

Adaptation of the cardiovascular system to weightlessness: Surprises, paradoxes and implications for deep space missions

Adaptation of the cardiovascular system to weightlessness: Surprises, paradoxes and implications for deep space missions

Falls and Fall-Prevention in Older Persons: Geriatrics Meets Spaceflight!

Bilateral Variation in the Course of Vertebral Artery

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