Considerations and anesthetic management of a patient with giant right atrial myxoma: A case report and literature review

BACKGROUND

Myxoma is a common type of primary cardiac tumor. However, there are few researches to illustrate challenge of safely inducing anesthesia in a patient with a giant right atrial myxoma at moderate altitude.

PATIENT CONCERNS AND DIAGNOSES

A 54-year-old female patient lived in a city with an average altitude of 1932 m with scheduled surgical treatment for giant right atrial myxoma, prompting discussions on appropriate anesthesia modalities given her prolonged residence at moderate altitude.

METHODS AND RESULTS

Considering the potential impact of moderate altitude on perioperative management, this study emphasizes the necessity of adequate volume preload therapy and the utility of transthoracic echocardiography or transesophageal echocardiography to prevent hemodynamic compromise. Furthermore, it highlights the unique consideration that, post-tumor removal, hypotension may not necessarily lead to decreased oxygen saturation in these patients.

CONCLUSION

This case underscores the importance of avoiding hypotension, as pre-tumor resection blood pressure maintenance primarily determines blood oxygen concentration. Additionally, it sheds light on the intriguing observation that post-tumor removal hypotension may not result in decreased oxygen saturation. These findings have significant implications for the perioperative care of patients with giant right atrial myxoma at moderate altitudes.

Physiological and Morphometric Differences in Resident Moderate-Altitude vs. Sea-Level Mice

INTRODUCTION: High-altitude [>2400 m (7874 ft)] acclimatization has been well studied with physiological adaptations like reductions in body weight and exercise capacity. However, despite the significance of moderate altitude [MA, 1524-2438 m (5000-8000 ft)], acclimatization at this elevation is not well described. We aimed to investigate differences in mice reared at MA compared to sea level (SL). We hypothesized that MA mice would be smaller and leaner and voluntarily run less than SL mice.METHODS: C57BL/6 mice reared for at least three generations in Laramie, WY [2194 m (7198 ft), MA], were compared to C57BL/6J mice from Bar Harbor, ME [20 m (66 ft), SL]. We quantified body composition and exercise outputs as well as cardiopulmonary morphometrics. Subsets of MA and SL mice were analyzed to determine differences in neuronal activation after exercise.RESULTS: When body weight was normalized to tibia length, SL animals weighed 1.30 g ⋅ mm-1 while MA mice weighed 1.13 g · mm-1. Total fat % and trunk fat % were higher in MA mice with values of 41% and 39%, respectively, compared to SL mice with values of 28% and 26%, respectively. However, no differences were noted in leg fat %. MA animals had higher heart mass (119 mg) and lower lung mass (160 mg) compared to SL mice heart mass (100 mg) and lung mass (177 mg). MA mice engaged in about 40% less voluntary wheel-running activity than SL animals.DISCUSSION: Physiological differences are apparent between MA and SL mice, prompting a need to further understand larger scale implications of residence at moderate altitude.O'Connor AE, Hatzenbiler DM, Flom LT, Bobadilla A-C, Bruns DR, Schmitt EE. Physiological and morphometric differences in resident moderate-altitude vs. sea-level mice. Aerosp Med Hum Perform. 2023; 94(12):887-893.

Prevalence and Characteristics of Symptomatic Intracranial Atherosclerotic Plaques in People Residing at Middle and High Altitudes: A Preliminary Study

BACKGROUND

This study aims to determine how atherosclerotic plaque prevalence and characteristics vary between individuals residing year-round at middle and high altitudes who have intracranial atherosclerotic disease.

METHODS

We conducted a retrospective analysis of patient data from our hospital, focusing on individuals with cerebrovascular symptoms who underwent high-resolution vessel wall imaging (HR-VWI). Patients who had lived at an altitude of <2500 meters for an extended period were classified in group A (n = 91), while those residing at an altitude of ≥2500 meters were placed in group B (n = 75). We examined the differences in plaque prevalence and characteristics between these two groups.

RESULTS

The detection rate of basilar artery plaque was higher in group A compared to group B (16% vs. 7.6%, p = 0.036). Conversely, the detection rate of anterior cerebral artery plaque was significantly lower in group A than in group B (4% vs. 11.8%, p = 0.016). The eccentricity index (EI) was greater in group B than in group A (0.72 ± 0.11 vs. 0.68 ± 0.12, p = 0.012). The prevalence of intraplaque hemorrhage (IPH) was lower in group B than in group A (39.5% vs. 58.7%, p = 0.002).

CONCLUSIONS

IPH prevalence was lower in patients residing at high altitudes than in those residing at middle altitudes. However, patients living at high altitudes had a higher EI compared to those residing at middle altitudes. These findings underscore the presence of disparities in the prevalence and characteristics of intracranial atherosclerotic plaques between individuals residing at medium and high altitudes. It is essential to account for these distinctions when diagnosing plaques.

Preventive Effect of Moderate Altitude on Non-Culprit Lesion Progression in Patients with Acute Myocardial Infarction

Wang, Jian, Cheng-Ying Yan, Wu Wang, and Tian-Zhen Wang. Preventive effect of moderate altitude on non-culprit lesion (NCL) progression in patients with acute myocardial infarction. High Alt Med Biol. 23:345-351, 2022. Background: Ischemic postconditioning may prevent NCL progression in patients with acute myocardial infarction. Moderate altitude (1,500-2,500 m) resembles ischemic postconditioning; however, the preventive effect of moderate altitude on NCL progression is unknown. Methods: We investigated the preventive effect of moderate altitude on NCL progression in patients with ST-segment elevation myocardial infarction (STEMI) after primary percutaneous coronary intervention (PPCI). This study was an observational study. Two-hundred patients with STEMI living in Beijing, which is an average of 43.5 m above sea level (a low-altitude region), who underwent PPCI were enrolled (the control group). A further 200 patients with STEMI living in Xining, which is an average of 2,261 m above sea level (moderate-altitude region), who underwent PPCI were enrolled (the moderate-altitude group). NCL progression and related clinical factors were compared between the two groups. Results: The rate of NCL progression 12 months after PPCI in the moderate-altitude group was significantly lower compared with the control group (p < 0.01). There were 158 patients without NCL progression (group A) and 42 patients with NCL progression (group B) in the control group and 186 patients without NCL progression (group C) and 14 patients with NCL progression (group D) in the moderate-altitude group. Serum adrenaline and noradrenaline concentrations in group B were significantly higher compared with group A (p < 0.001), and serum adrenaline and noradrenaline concentrations in group D were significantly higher compared with group C (p < 0.001). Serum adrenaline, noradrenaline, and C-reactive protein concentrations in patients without NCL progression (n = 344) were significantly lower compared with patients with NCL progression (n = 56) (p < 0.01). Conclusions: Moderate altitude may prevent NCL progression. Moderate altitude may be useful for clinical rehabilitation in patients with STEMI after PPCI.

Effects of Long-Term Exposure to 2260 m Altitude on Working Memory and Resting-State Activity in the Prefrontal Cortex: A Large-Sample Cross-Sectional Study

It has been well established that very-high-altitude (>4000 m) environments can affect human cognitive function and brain activity. However, the effects of long-term exposure to moderate altitudes (2000−3000 m) on cognitive function and brain activity are not well understood. In the present cross-sectional study, we utilized an N-back working memory task and resting-state functional near-infrared spectroscopy to examine the effects of two years of exposure to 2260 m altitude on working memory and resting-state brain activity in 208 college students, compared with a control group at the sea level. The results showed that there was no significant change in spatial working memory performance after two years of exposure to 2260 m altitude. In contrast, the analysis of resting-state brain activity revealed changes in functional connectivity patterns in the prefrontal cortex (PFC), with the global efficiency increased and the local efficiency decreased after two years of exposure to 2260 m altitude. These results suggest that long-term exposure to moderate altitudes has no observable effect on spatial working memory performance, while significant changes in functional connectivity and brain network properties could possibly occur to compensate for the effects of mild hypoxic environments. To our knowledge, this study is the first to examine the resting state activity in the PFC associated with working memory in people exposed to moderate altitudes.

Stroke at Moderate and High Altitude

Syed, Maryam J., Ismail A. Khatri, Wasim Alamgir, and Mohammad Wasay. Stroke at moderate and high altitude. High Alt Med Biol. 23:1-7, 2022. Background: Stroke at high altitude is an understudied area in stroke research. With improvements in road infrastructure, access to high-altitude areas for recreation and living purposes has risen. Subsequently, it has been anticipated that due to normal physiological changes to high altitude the incidence of stroke is also likely to increase in these regions. Methods: We searched PubMed for available literature about stroke at high altitude. Cross-referencing was done from available articles and through other scientific search engines. Relevant case series and case reports were included in this review of the topic. Results: Only one review article, eight case series (including review of literature), and seven case reports were identified that could be included in this review. Most of the available data come from moderate and high altitude. Conclusions: There is limited available literature about stroke at high and extreme altitudes. Stroke at high altitude is likely to become an important subset of stroke population. Currently, there is inadequate knowledge about the incidence and prevalence, mechanisms, and stroke outcomes. Cerebral venous thrombosis is more common than arterial stroke. Stroke is probably secondary to conventional risk factors, polycythemia, and other coagulopathies. A case-control study may identify the at-risk population for stroke at moderate and high altitudes.

Impact of moderate altitude exposure on cardiovascular risk

Acute exposure to extreme altitude increases arterial stiffness by activation of the sympathetic and endothelin system as well as hypoxia-induced reactive oxygen species production. Beyond a certain individual threshold, these physiological adaptations represent a relevant cardiovascular risk factor. In this pilot study we investigated to what extent temporary exposure to moderate altitude, as present during hiking, skiing or in aeroplanes, leads to changes in vascular tone. Pulse wave parameters of 8 healthy individuals were assessed with a BR-102 plus pulse wave analyser (Schiller, Germany) at baseline (521 m) and after 24 h exposure to moderate altitude (2650 m). We identified a significant increase in heart rate (61 vs. 68/min, p = 0.021) as well as changes in central (35.6 vs. 41.4 mmHg, p = 0.024) and peripheral pulse pressure (44.7 vs. 52.6 mmHg, p = 0.006). Amplitudes of forward (21.6 vs. 25.4 mmHg, p = 0.012) and backward pulse waves (15.3 vs. 17.6 mmHg, p = 0.043) were significantly elevated. Pulse wave velocity showed no significant change from 5.8 m/s at baseline to 6.1 m/s at moderate altitude (p = 0.056). We show that temporary exposure to moderate altitude leads to mild changes in vascular tone reflected by pulse pressure and pulse wave amplitude in healthy adults. Although the observed effects were mild in our study, it indicates that adaptation capacity is of crucial importance and any restrictions by disease or simply with the process of ageing demand increased awareness, even in moderate altitude.

Acute Moderate Hypoxia Reduces One-Legged Cycling Performance Despite Compensatory Increase in Peak Cardiac Output: A Pilot Study

In severe hypoxia, single-leg peak oxygen uptake (VO_2peak) is reduced mainly due to the inability to increase cardiac output (CO). Whether moderate altitude allows CO to increase during single-leg cycling, thereby restoring VO_2peak, has not been extensively investigated. Five healthy subjects performed an incremental, maximal, two-legged cycle ergometer test, and on separate days a maximal incremental one-leg cycling test in normoxia and in moderate hypoxia (fraction of inspired oxygen (FiO₂) = 15%). Oxygen uptake, heart rate, blood pressure responses, power output, and CO (PhysioFlow) were measured during all tests. Moderate hypoxia lowered single-leg peak power output (154 ± 31 vs. 128 ± 26 watts, p = 0.03) and oxygen uptake (VO₂) (36.8 ± 6.6 vs. 33.9 ± 6.9 mL/min/kg, p = 0.04), despite higher peak CO (16.83 ± 3.10 vs. 18.96 ± 3.59 L/min, p = 0.04) and systemic oxygen (O₂) delivery (3.37 ± 0.84 vs. 3.47 ± 0.89 L/min, p = 0.04) in hypoxia compared to normoxia. Arterial–venous O₂ difference (a–vDO₂) was lower in hypoxia (137 ± 21 vs. 112 ± 19 mL/l, p = 0.03). The increases in peak CO from normoxia to hypoxia were negatively correlated with changes in mean arterial pressure (MABP) (p < 0.05). These preliminary data indicate that the rise in CO was not sufficient to prevent single-leg performance loss at moderate altitude and that enhanced baroreceptor activity might limit CO increases in acute hypoxia, likely by reducing sympathetic activation. Since the systemic O₂ delivery was enhanced and the calculated a–vDO₂ reduced in moderate hypoxia, a potential diffusion limitation cannot be excluded.

Is Altitude Training Bad for the Running Mechanics of Middle-Distance Runners?

AIMS

It has been hypothesized that altitude training may alter running mechanics due to several factors such as the slower training velocity with associated alteration in muscle activation and coordination. This would lead to an altered running mechanics attested by an increase in mechanical work for a given intensity and to the need to "re-establish" the neuromuscular coordination and running biomechanics postaltitude. Therefore, the present study aimed to test the hypothesis that "live high-train high" would induce alteration in the running biomechanics (ie, longer contact time, higher vertical oscillations, decreased stiffness, higher external work).

METHODS

Before and 2 to 3 days after 3 weeks of altitude training (1850-2200 m), 9 national-level middle-distance (800-5000 m) male runners performed 2 successive 5-minute bouts of running at moderate intensity on an instrumented treadmill with measured ground reaction forces and gas exchanges. Immediately after the running trials, peak knee extensor torque was assessed during isometric maximal voluntary contraction.

RESULTS

Except for a slight (-3.0%; P = .04) decrease in vertical stiffness, no mechanical parameters (stride frequency and length, contact and flight times, ground reaction forces, and kinetic and potential work) were modified from prealtitude to postaltitude camp. Running oxygen cost was also unchanged.

DISCUSSION

The present study is the first one to report that "live high-train high" did not change the main running mechanical parameters, even when measured immediately after the altitude camp. This result has an important practical implication: there is no need for a corrective period at sea level for "normalizing" the running mechanics after an altitude camp.

Clinical Course of Pediatric Acute Respiratory Distress Syndrome at Moderate Altitude

Background

This is a retrospective case series, and the main objective is to describe the epidemiology, clinical features, and outcomes of pediatric acute respiratory distress syndrome in patients at moderate altitude.

Methods

Children from the Pediatric Intensive Care Unit (PICU) at the Fundación Cardioinfantil, hospitalized with acute respiratory distress syndrome, were prospectively enrolled from March 2009 to March 2014. We evaluated the demographic data, mechanical ventilation, gas exchange, hemodynamics, and multiorgan dysfunction.

Results

During the study period, 88 patients met the inclusion criteria. Bronchiolitis and pneumonia were the most common causes of acute respiratory distress syndrome. The overall mortality rate was 19.5%. At the beginning of the study, the average relation between blood pressure and the fraction of inspired oxygen (Pa/Fi) was 130.3 ± 52.2; tidal volume was 7.94 ± 1.7 ml/kg, the plateau pressure 25.3 ± 5.09 cmH₂O, and positive end-expiratory pressure was 7.2 ± 3.2 cmH₂O. After 24 hours, the mortality rate in the group with severe acute respiratory distress syndrome (Pa/Fi <100) was 46.7%, in the moderate acute respiratory distress syndrome group (Pa/Fi 100-200) it was 11.9%, and finally in the mild acute respiratory distress syndrome group (Pa/Fi 200-300) the mortality was 25%. This study found a relation between serum lactate value and positive end-expiratory pressure and mortality (p = 0.02 and 0.0013).

Conclusions

This study shows that pediatric acute respiratory distress syndrome patients at moderate altitudes have similar clinical behavior, including mortality rate, to those at low altitudes. However, Pa/Fi is not a good predictor of mortality for patients with mild and moderate acute respiratory distress syndrome.

Effects of hiking at moderate and low altitude on cardiovascular parameters in male patients with metabolic syndrome: Austrian Moderate Altitude Study

OBJECTIVE

Physical activity is a cornerstone in therapy for patients with metabolic syndrome. Walking and hiking in a mountain scenery represents an ideal approach to make them move. The Austrian Moderate Altitude Study (AMAS) 2000 main study is a randomized controlled trial to investigate the cardiovascular effects of hiking at moderate altitude on patients with metabolic syndrome compared with a control group at low altitude, to assess a potential altitude-specific effect.

METHODS

Seventy-one male patients with metabolic syndrome were randomly assigned to a moderate altitude group (at 1700 m), with 36 participants, or to a low altitude group (at 200 m), with 35 participants. The 3-week vacation program included 12 hiking tours (4 per week, average duration 2.5 hours, intensity 55% to 65% of heart rate maximum). Physical parameters, performance capacity, 24-hour blood pressure, and heart rate profiles were obtained before, during, and after the stay.

RESULTS

In both groups, we found a significant mean weight loss of -3.13 kg; changes in performance capacity were minor. Systolic, diastolic, and mean arterial pressures and circadian heart rate profiles were significantly reduced in both groups, with no differences between them. Consequently, the pressure-rate product was reduced as well. All study participants tolerated the vacation well without any adverse events.

CONCLUSIONS

A 3-week hiking vacation at moderate or low altitude is safe for patients with metabolic syndrome and provides several improvements in their cardiovascular parameters. The cardiovascular benefits achieved are more likely to be the result of regular physical activity than the altitude-specific effect of a mountain environment.

Prevalence of metabolic syndrome among newly diagnosed hypertensive patients in the hills of Himachal Pradesh, India

To study the prevalence of metabolic syndrome (MS) among newly diagnosed hypertensive patients in a tertiary care hospital in the northern hilly state of Himachal Pradesh, India, located in western Himalayas at a moderate altitude of 2200 m above mean sea level. One hundred and eighteen newly diagnosed hypertensive patients above the age of 20 years were studied in a hospital-based cross-sectional study. MS prevalence was estimated by International Diabetes Federation (IDF) criteria and modified National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) criteria. Student's t-test was used to compare the mean of the continuous variables. Chi-square test was used to compare discrete variables. The prevalence of MS in hypertensive patients was 68.6% (modified NCEP-ATP III) and 63.6% (IDF criteria). The most common phenotype of MS with the component of hypertension was the coexistence of waist circumference (90.1%), low high-density lipoprotein (HDL; 70.4%), and high triglycerides (67.9%) as per the modified NCEP-ATP III criteria, and low HDL (76.2%) and high triglycerides (66.4%) as per the IDF criteria. Fasting blood glucose (33.2% as per the modified NCEP-ATP III criteria and 32.6% as per the IDF criteria) was the least significant factor having an association with MS. The prevalence of MS among hypertensive patients was high and indicates the need for metabolic screening in all hypertensive patients at the first diagnosis.

Prevalence and determinants of hyperlipidemia in moderate altitude areas of the Yunnan-Kweichow plateau in Southwestern China

The objective of the current study was to determine the prevalence and determinants of hyperlipidemia among the populations living at moderate altitude on the Yunnan-Kweichow Plateau in Southwestern China. We randomly recruited 1415 people for this study. These subjects underwent a physical examination and a comprehensive questionnaire regarding their daily habits and diets. Furthermore, blood samples from the participants were collected for assessing the lipid profile. We found that 49.3% of participants (95% CI: 46.7-51.9%) suffered from hyperlipidemia. The prevalence in men was significantly higher than that in women (53.6% vs. 44.7%, p<0.01). The prevalence of hypercholesterolemia was 23.3% and of hypertriglyceridemia was 34.1%. Low HDL-C showed a prevalence of 17.5% and high LDL-C of 9.0%. The prevalence of hyperlipidemia also increased with age, as did the prevalence of high TC, TG, and LDL-C. Hyperlipidemic subjects tended to be older and have a higher BMI and WHR than the normolipidemic subjects in the study cohort (p<0.05). The hyperlipidemic subjects, both men and women, tended to dine out often and consume more animal-based foods and alcohol. In addition, the hyperlipidemic men in our cohort consumed more salted food then their normolipidemic counterparts (p<0.01). Normolipidemic subjects of both sexes were also found to prefer a vegetarian diet (p<0.01). Age, alcohol consumption, a preference for meat and animal products, regular dining out, and BMI were found to be the main determinants of hyperlipidemia in women, whereas a prevalence of salted food was observed to be related to hyperlipidemia in men from the Yunnan-Kweichow Plateau subpopulation under study (p<0.05). The average daily energy, and protein and fat intakes of the sampled subjects were also higher than the levels set by the Chinese Recommendation Nutrient Intakes (RNI), while hyperlipidemic subjects had an even higher average daily intake of total fat, cholesterol, and lower dietary fiber compared with the normolipidemic subjects in the study group (p<0.05). In conclusion, this study reveals a higher prevalence of hyperlipidemia, hypercholesterolemia, hypertriglyceridemia, increased BMI and WHR values in men, as well as a slightly higher prevalence of low HDL-C and high LDL-C in women from Yunnan-Kweichow Plateau. The incidence of hyperlipidemia also increased with age, as did the prevalence of an abnormal TC, TG, LDL-C, and WHR in our study cohort. A high BMI, and less healthy living habits and dietary preferences thus play significant roles in the onset of hyperlipidemia.

Effect of moderate altitude on peripheral muscle oxygenation during leg resistance exercise in young males

Training at moderate altitude (~1800m) is often used by athletes to stimulate muscle hypoxia. However, limited date is available on peripheral muscle oxidative metabolism at this altitude (1800AL). The purpose of this study was to determine whether acute exposure to 1800AL alters muscle oxygenation in the vastus lateralis muscle during resistance exercise. Twenty young active male subjects (aged 16 - 21 yr) performed up to 50 repetitions of the parallel squat at 1800AL and near sea level (SL). They performed the exercise protocol within 3 h after arrival at 1800 AL. During the exercise, the changes in oxygenated hemoglobin (OxyHb) in the vastus lateralis muscle, arterial oxygen saturation (SpO2), and heart rate were measured using near infrared continuous wave spectroscopy (NIRcws) and pulse oximetry, respectively. Changes in OxyHb were expressed by Deff defined as the relative index of the maximum change ratio (%) from the resting level. OxyHb in the vastus lateralis muscle decreased dramatically from the resting level immediately after the start of exercise at both altitudes. The Deff during exercise was significantly (p < 0.001) lower at 1800AL (60.4 ± 6.2 %) than at near SL (74.4 ± 7.6 %). SpO2 during exercise was significantly (p < 0.001) lower at 1800AL (92.0 ± 1.7 %) than at near SL (96.7 ± 1.2 %). Differences (SL - 1800AL) in Deff during exercise correlated fairly strongly with differences in SpO2 during exercise (r = 0.660). These results suggested that acute exposure to moderate altitude caused a more dramatical decrease in peripheral muscle oxygenation during leg resistance exercise. It is salient to note, therefore, that peripheral muscle oxygenation status at moderate altitude could be evaluated using NIRcws and that moderate altitudes might be effectively used to apply hypoxic stress on peripheral muscles. Key PointsThe change in muscle oxygenation during the parallel squat at 1800 altitude and near sea level was investigated using near infrared continuous wave spectroscopy (NIRcws)The muscle oxygenation during exercise at 1800 altitude decreased more dramatically compared to sea level.NIRcws could help to provide a better understanding of exercising muscle metabolism at moderate altitude.