ABSTRACT
BACKGROUND: Research on degenerative abdominal aortic aneurysms (AAA) is hampered by complex pathophysiology, sub-optimal pre-clinical models, and lack of effective medical therapies. In addition, trustworthiness of existing epidemiological data is impaired by elements of ambiguity, inaccuracy, and inconsistency. Our aim is to foster debate concerning the trustworthiness of AAA epidemiological data and to discuss potential solutions. METHODS: We searched the literature from the last five decades for relevant epidemiological data concerning AAA development, rupture, and repair. We then discussed the main issues burdening existing AAA epidemiological figures and proposed suggestions potentially beneficial to AAA diagnosis, prognostication, and management. RESULTS: Recent data suggest a heterogeneous scenario concerning AAA epidemiology with rates markedly varying by country and study cohorts. Overall, AAA prevalence seems to be decreasing worldwide while mortality is apparently increasing regardless of recent improvements in aortic-repair techniques. Prevalence and mortality are decreasing in high-income countries, whereas low-income countries show an increase in both. However, several pieces of information are missing or outdated, thus systematic renewal is necessary. Current AAA definition and surgical criteria do not consider inter-individual variability of baseline aortic size, further decreasing their reliability. CONCLUSIONS: Switching from flat aortic-size thresholds to relative aortic indices would improve epidemiological trustworthiness regarding AAAs. Aortometry standardization focusing on simplicity, univocity, and accuracy is crucial. A patient-tailored approach integrating clinical data, multi-adjusted indices, and imaging parameters is desirable. Several novel imaging modalities boast promising profiles for investigating the aortic wall. New contrast agents, computational analyses, and artificial intelligence-powered software could provide further improvements.
ABSTRACT
Precise, sensitive, and non-invasive estimates of stroke volume index (SVI) would facilitate clinical decision making and tracking of cardiorespiratory fitness in space. Thoracic electrical bioreactance (TEBR) is capable of providing valid SVI estimates on Earth; however, its reliability in response to simulated sustained gravitational transitions is unknown. Ten healthy male subjects underwent short-arm human centrifugation (SAHC) equivalent to 1 g and 1.5 g at their center of mass along the z-axis (gz) for 10 min each (first 5 min: passive; last 5 min: active, leg press movements), interspersed by periods without centrifugation (µg). The TEBR-based device Starling™ SV was used to estimate SVI during the five distinct passive gz phases. Precision of SVI measurements and sensitivity to hemodynamic changes induced by simulated gz transitions were determined. Overall SVI precision was very high (coefficient of variation = 3.6%), whereas mean sensitivity to SVI changes was satisfactory (sensitivity index = 75%). This study shows that the TEBR-based device Starling™ SV is precise and sensitive to hemodynamic changes in response to simulated sustained gz transitions induced by SAHC. Thus, it may be a suitable non-invasive hemodynamic monitor during human spaceflight. Further evaluation of Starling™ SV against a reference method in simulated microgravity is warranted.
