Deep Vein Thrombosis and Pulmonary Embolism in a Mountain Guide: Awareness, Diagnostic Challenges, and Management Considerations at Altitude

The Profiles of Venous Thromboembolism at Different High Altitudes

Xiong, Shiqiang, Jun Hou, Haixia Yang, Meiting Gong, Xin Ma, Xuhu Yang, Hongyang Zhang, Yao Ma, Liang Gao, and Haifeng Pei. The profiles of venous thromboembolism at different high altitudes High Alt Med Biol. 00:000-000, 2024.-This study investigated the incidence of venous thromboembolism (VTE) in high altitude (HA) and very HA areas. Patients with deep vein thrombosis (DVT) or pulmonary embolism (PE) diagnosed between 2004 and 2022 in Yecheng, China, were retrospectively analyzed. The results showed that patients with PE at very HA had a higher risk of lower extremity DVT (OR 16.3 [95% CI 1.2-223.2], p = 0.036), than those at HA, especially in the early stages of very HA entry, and the harsh environment of very HA further exacerbated the risk of VTE. These findings emphasize the higher risk of PE development in very HA and the need for enhanced prevention and treatment in this area.

Altitude-Related Venous Thrombosis With Heart Disease: An Updated Review

Altitude-related venous thrombosis (ARVT) is a condition of growing concern among individuals engaged in high-altitude travel and activities. This updated review explores the epidemiology, pathophysiological mechanisms, clinical presentations, and management of ARVT based on a thematic analysis and synthesis of the existing literature. ARVT's multifactorial etiology involves the interplay of hypobaric hypoxia and endothelial dysfunction, creating a procoagulant state and increasing the risk of thrombosis. Common clinical manifestations include pain, swelling, and redness in the extremities, necessitating accurate and timely diagnosis, particularly in remote settings. Thromboprophylaxis during high-altitude travel and activities plays a crucial role in reducing the risk of ARVT, while anticoagulation remains the mainstay of management. Further research is needed to optimize preventive and treatment strategies, enhancing patient outcomes and safety in high-altitude environments.

Potential long-term effects of SARS-CoV-2 infection on the pulmonary vasculature: Multilayered cross-talks in the setting of coinfections and comorbidities

The Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its sublineages pose a new challenge to healthcare systems worldwide due to its ability to efficiently spread in immunized populations and its resistance to currently available therapies. COVID-19, although targeting primarily the respiratory system, is also now well established that later affects every organ in the body. Most importantly, despite the available therapy and vaccine-elicited protection, the long-term consequences of viral infection in breakthrough and asymptomatic individuals are areas of concern. In the past two years, investigators accumulated evidence on how the virus triggers our immune system and the molecular signals involved in the cross-talk between immune cells and structural cells in the pulmonary vasculature to drive pathological lung complications such as endothelial dysfunction and thrombosis. In the review, we emphasize recent updates on the pathophysiological inflammatory and immune responses associated with SARS-CoV-2 infection and their potential long-term consequences that may consequently lead to the development of pulmonary vascular diseases.

Time Course of Coagulo-Fibrinolytic Derangements During Acclimatization to High Altitude in Rabbits and a Preliminary Study on the Possible Mechanisms

Zhong, Xin, Zhao Ye, Xiaolin Zhou, Renqing Jiang, Yijun Jia, Wenqiong Du, Haoyang Yang, Lin Zhang, Bai Lu, and Zhaowen Zong. Time course of coagulo-fibrinolytic derangements during acclimatization to high altitude in rabbits and a preliminary study on the possible mechanisms. High Alt Med Biol. 00:000-000, 2022. Background: Conflicting data exist regarding changes in the coagulation system during acclimatization to high altitude (HA), which makes the prevention of thromboembolic events difficult. The present study aimed at observing the dynamic changes in the coagulo-fibrinolysis system during acclimatization to HA and at exploring the possible mechanisms. Materials and Methods: Twenty rabbits of both sexes were randomly divided into two groups, including group A rabbits (healthy plain controls) and group B rabbits (acutely exposed to HA). A traditional coagulation test, thromboelastography analysis, and full blood cell count were used to assess the coagulo-fibrinolytic changes at different time points. Plasma was collected to examine the levels of relevant biomarkers. Results: Six hours and 1 day after acute exposure to HA, the coagulo-fibrinolytic system demonstrated a hypercoagulable state. Further, 3 days after exposure to HA, group B rabbits showed hypocoagulability, increased fibrinolysis, and lower clot firmness and 7 days after exposure to HA, delayed coagulation, decreased fibrinolysis, and increased clot firmness were observed. Subsequently, 14, 21, and 28 days after exposure to HA, we found increased clot firmness. Increased platelet counts and concentrations of fibrinogen and plasminogen activator inhibitor-1 contributed to this change. Conclusion: The coagulo-fibrinolytic derangements during acclimatization to HA in rabbits demonstrated a dynamic pattern.

Sport and Venous Thromboembolism

BACKGROUND

The occurrence of venous thromboembolisms (VTE) in association with sporting activity has been described but not yet systematically explored. The aim of this study was to determine the sites at which VTE occur in athletes, the accompanying features, and the special features of the symptoms and diagnosis, so that physicians can take the findings into consideration.

METHODS

A search of the literature in the databases PubMed, Web of Science, and Cochrane in accordance with the PRISMA criteria, together with a search of Google Scholar up to 29 February 2020.

RESULTS

No observational studies were identified. A total of 154 case descriptions were evaluated: 89 on upper-extremity deep vein thrombosis (DVT), 53 on lower-extremity DVT, and 12 on pulmonary embolisms with no evidence of thrombosis. Ninety-five percent of the upper-extremity DVT involved the region of the subclavian/axillary vein. Thoracic outlet syndrome (38%), hereditary thrombophilia/a family history of VTE (16%), intensive training (12%), and the use of oral contraceptives (7%) were identified as accompanying features. The upper-extremity DVT occurred mainly in male strength athletes and ball sports players. The lower-extremity DVT were located in the lower leg/knee (30%), the thigh (19 %), or occurred in combination in the lower leg-to-pelvis region (30 %). The features accompanying lower-extremity DVT were hereditary thrombophilia/a family history of VTE (30%), trauma (25%), immobilization (21%), and the use of oral contraceptives (11%). The lower-extremity DVT were found in endurance sports and ball sports. The symptoms may be obscured by sport-specific symptoms/trauma, and diagnosis is often delayed. Early D-dimer determination is useful and is complemented by diagnostic imaging.

CONCLUSION

VTE are found in association with sports. The background factors, the sites of VTE, the types of sports involved, and the accompanying features are all important to know. The symptoms may be obscured, and it may be difficult to reach the correct diagnosis. The possible presence of DVT must be borne in mind.

Incidence of silent venous thromboembolism after total hip arthroplasty: A comparison of rivaroxaban and enoxaparin

PROPOSE

Total hip arthroplasty (THA) is associated with a significant risk of venous thromboembolism (VTE). Different thromboprophylaxis strategies have been used to prevent VTE. The primary aim of this study was to report the incidence of VTE and compare the efficacy and safety of rivaroxaban to enoxaparin. The secondary outcome was to report the incidence of silent deep venous thrombosis (DVT) using computed tomography venography.

METHODS

One hundred sixty patients who underwent THA were enrolled in a prospective study. Patients were randomized into two groups as follows: those who received rivaroxaban 10 mg oral daily (group RXE) and those who received enoxaparin 40 IU/day subcutaneously for 14 days (group ENO).

RESULTS

Both groups were matched for age, sex, comorbidities, special habits and preoperative laboratory investigations. The overall incidence of DVT was 5% (n = 8), which included four patients clinically diagnosed as having DVT and four with silent DVT. All the DVT cases occurred in veins below the knee and in the group RXE; none of the cases occurred in group ENO (p = 0.04). The incidence of DVT was significantly higher in patients with high body mass indexes (p < 0.001), older age (p = 0.024) and medical comorbidities (p = 0.14). No mortality, pulmonary embolism, stroke, wound infection or major bleeding occurred in either group.

CONCLUSIONS

Among the patients who underwent hip arthroplasty, rivaroxaban prophylaxis was found to be associated with lower efficacy and similar safety outcomes as compared with enoxaparin anticoagulants.

Identification and Characterization of Plasmin-Independent Thrombolytic Enzymes

Supplemental Digital Content is available in the text.

Rationale:

Current thrombolytic agents activate plasminogen to plasmin which triggers fibrinolysis to dissolve thrombi. Since plasmin is a nonspecific proteolytic enzyme, all of the current plasmin-dependent thrombolytics lead to serious hemorrhagic complications, demanding a new class of fibrinolytic enzymes independent from plasmin activation and undesirable side effects. We speculated that the mammalian version of bacterial heat-shock proteins could selectively degrade intravascular thrombi, a typical example of a highly aggregated protein mixture.

Objective:

The objective of this study is to identify enzymes that can dissolve intravascular thrombi specifically without affecting fibrinogen and fibronectin so that the wound healing processes remain uninterrupted and tissues are not damaged. In this study, HtrA (high-temperature requirement A) proteins were tested for its specific proteolytic activity on intravascular thrombi independently from plasmin activation.

Methods and Results:

HtrA1 and HtrA2/Omi proteins, collectively called as HtrAs, lysed ex vivo blood thrombi by degrading fibrin polymers. The thrombolysis by HtrAs was plasmin-independent and specific to vascular thrombi without causing the systemic activation of plasminogen and preventing nonspecific proteolysis of other proteins including fibrinogen and fibronectin. As expected, HtrAs did not disturb clotting and wound healing of excised wounds from mouse skin. It was further confirmed in a tail bleeding and a rebleeding assay that HtrAs allowed normal clotting and maintenance of clot stability in wounds, unlike other thrombolytics. Most importantly, HtrAs completely dissolved blood thrombi in tail thrombosis mice, and the intravenous injection of HtrAs to mice with pulmonary embolism completely dissolved intravascular thrombi and thus rescued thromboembolism.

Conclusions:

Here, we identified HtrA1 and HtrA2/Omi as plasmin-independent and highly specific thrombolytics that can dissolve intravascular thrombi specifically without bleeding risk. This work is the first report of a plasmin-independent thrombolytic pathway, providing HtrA1 and HtrA2/Omi as ideal therapeutic candidates for various thrombotic diseases without hemorrhagic complications.

Venous thrombosis at altitude presents with distinct biochemical profiles: a comparative study from the Himalayas to the plains

High-altitude (HA) hypoxia exposure is believed to induce venous thromboembolism (VTE) in otherwise healthy individuals, although this needs to be fully established. The present study aims to ascertain the role of HA exposure in aggravating any predisposition toward VTE and to explore whether the etiology of HA-induced VTE is different from that of VTE closer to sea level. We compared manifestation-matched male VTE patients from HA (HAPs) and VTE patients from the plains closer to sea level (SLPs) for 54 parameters, including coagulation-related, fibrinolytic, and thrombophilic variables, as well as markers for stress and inflammatory response and platelet and endothelial activation. Our results established an association between HA hypoxia and VTE in alterations of primarily hemostatic variables. Approximately 96% of HAPs presented with ≥10 altered parameters out of 54 studied compared with 7% of SLPs. Elevated platelet count, von Willebrand factor, and clotting factors and altered coagulation exhibited significant associations with VTE events and altitude exposure (all P < .05). Additionally, most VTEs at HA were associated with younger age groups, unlike those on the plains. A receiver operator characteristic curve analysis revealed differences between HAPs and SLPs for CD40 ligand (area under the curve [AUC], 0.90; 95% confidence interval [CI], 0.84-0.96]), P-selectin (0.79; 0.70-0.88), platelet factor-4 (0.90; 0.84-0.96), intracellular adhesion molecule-1 (0.86; 0.79-0.93), vascular cell adhesion molecule-1 (0.97; 0.95-0.99), vascular endothelial growth factor (0.87; 0.8-0.94), FLT4 (0.94; 0.89-0.99), and Toll-like receptor-2 (0.98; 0.96-1.0) (all P < .05). In conclusion, this study suggests that HA exposure perturbs the molecules associated with vascular integrity and contributes to the early onset of VTE.

The Complexity of Diagnosing High-Altitude Pulmonary Edema: A Case Report and Review of the Differential Diagnosis of Greater Than Expected Hypoxemia at Altitude

High-altitude pulmonary edema (HAPE) is a common presumptive diagnosis for a patient who experiences significant dyspnea and cyanosis at altitude. In this study, we present a case of a 58-year-old woman who was initially diagnosed with HAPE, although further evaluation revealed the presence of two underlying contributors to her significant hypoxemia at altitude. We discuss the medical workup for causes of greater than expected hypoxemia at altitude and the role some relevant medical comorbidities may play.

An Occupational Health Survey of British Mountain Guides Operating Internationally

INTRODUCTION

Professional mountain guides face significant occupational health risks, including injuries, accidents, environmental exposures, chronic musculoskeletal strain, and psychological stressors. This study aims to investigate these risks and their impact on the quality of life of a group of international British mountain guides.

METHODS

This self-reported online survey included demographics; acute and chronic occupational conditions; and questions on general health, lifestyle, symptoms of post-traumatic stress disorder (PTSD), and quality of life based on the World Health Organization quality of life [WHOQOL-BREF] questionnaire.

RESULTS

Responses were received from 67 (32%) of the approached guides. Knee pain (75%), back and neck pain (62%), hand/upper extremity problems (51%), and lower limb injuries (49%) were the most commonly reported individual occupational health problems. Chronic eye problems were reported by 8%, and 5% reported skin cancer. Twenty-nine percent were on regular medications, which were mainly analgesics for chronic musculoskeletal complaints. Mountain guides have a healthy lifestyle, with lower rates of being overweight/obese, alcohol consumption, and smoking than the average UK population. Fourteen (61%) of the 23 guides responding to the PTSD questions reported experiencing life-threatening traumatic incidents, and 4 (25%) of this subgroup appear to have had some symptoms of PTSD. The quality of life assessment showed that the studied mountain guides have a high quality of life.

CONCLUSIONS

Musculoskeletal problems are the main occupational health problems experienced by the study group. New findings include a low but important prevalence of ultraviolet radiation-associated conditions. One in 3 guides have experienced significant psychological trauma, and one quarter of these had symptoms of PTSD.

Venous Thromboembolism Within Professional American Sport Leagues

Background

Numerous reports have described players in professional American sports leagues who have been sidelined with a deep vein thrombosis (DVT) or a pulmonary embolism (PE), but little is known about the clinical implications of these events in professional athletes.

Purpose

To conduct a retrospective review of injury reports from the National Hockey League (NHL), Major League Baseball (MLB), the National Basketball Association (NBA), and the National Football League (NFL) to take a closer look at the incidence of DVT/PE, current treatment approaches, and estimated time to return to play in professional athletes.

Study Design

Descriptive epidemiology study.

Methods

An online search of all team injury and media reports of DVT/PE in NHL, MLB, NBA, and NFL players available for public record was conducted by use of Google, PubMed, and SPORTDiscus. Searches were conducted using the professional team name combined with blood clot, pulmonary embolism, and deep vein thrombosis.

Results

A total of 55 venous thromboembolism (VTE) events were identified from 1999 through 2016 (NHL, n = 22; MLB, n = 16; NFL, n = 12; NBA, n = 5). Nineteen athletes were reported to have an upper extremity DVT, 15 had a lower extremity DVT, 15 had a PE, and 6 had DVT with PE. Six athletes sustained more than 1 VTE. The mean age at time of VTE was 29.3 years (range, 19-42 years). Mean (±SD) time lost from play was 6.7 ± 4.9 months (range, 3 days to career end). Seven athletes did not return to play. Players with upper extremity DVT had a faster return to play (mean ± SD, 4.3 ± 2.7 months) than those with lower extremity DVT (5.9 ± 3.8 months), PE (10.8 ± 6.8 months), or DVT with PE (8.2 ± 2.6 months) (F = 5.69, P = .002). No significant difference was found regarding time of return to play between sports.

Conclusion

VTE in professional athletes led to an average of 6.7 months lost from play. The majority of athletes were able to return to play after a period of anticoagulation or surgery. Those with an upper extremity DVT returned to play faster than those with other types of VTE. Further study is needed to look into modifiable risk factors for these events and to establish treatment and return-to-play guidelines to ensure the safety of these athletes.

Performance of wells score to predict deep vein thrombosis and pulmonary embolism in endurance athletes

INTRODUCTION

There are an increasing number of reports describing deep vein thrombosis (DVT) and/or pulmonary embolism (PE) in otherwise healthy endurance athletes. The Wells score is the most commonly used clinical prediction rule to diagnose DVT/PE in clinical populations. However, the Wells score may have limited utility for recognition of DVT/PE in athletes, contributing to missed or delayed diagnosis.

OBJECTIVE

We performed an analysis of the ability of the Wells score to identify DVT/PE events in athletes through a review of published case reports.

METHODS

A systematic search of the literature yielded 11 case reports.

RESULTS

The Wells score had a 100% failure rate in identifying athletes with DVT (0/6) and PE (0/5), resulting in a delayed diagnosis for DVT of 20 ± 14 days. Retrospectively removing 'differential diagnosis' from the clinical prediction rule for DVT changed the Wells score median from 0 (range: -1 to 0) to 2 (range: 1 to 2); the threshold for predicting DVT as 'likely'. There were limited clinical characteristics captured in the Wells score for PE that were applicable to athletes, highlighting the need for reappraisal. Although the Wells score failed to accurately triage athletes with known DVT and/or PE, the addition of a D-dimer value (mean: 1566 ± 758ng/dL) to the Wells score correctly identified 9/9 athletes.

CONCLUSIONS

The Wells score had a 100% failure rate for triaging athletes with known DVT/PE. When performed, D-dimer adequately facilitated the additional diagnostic testing required for a timely diagnosis of DVT/PE in athletes. Improving awareness of an atypical presentation of thrombotic events in athletes may reduce the widespread underestimation of DVT/PE among athletes and facilitate the additional testing required for a timely diagnosis.

Adropin Is a Key Mediator of Hypoxia Induced Anti-Dipsogenic Effects via TRPV4-CamKK-AMPK Signaling in the Circumventricular Organs of Rats

Water intake reduction (anti-dipsogenic effects) under hypoxia has been well established, but the underlying reason remains unknown. Our previous report indicated that activated TRPV4 neurons in SFO are associated with anti-dipsogenic effects under hypoxia. Although low partial pressure of blood oxygen directly activates TRPV4, humoral factors could also be involved. In the present study, we hypothesize that adropin, a new endogenous peptide hormone, was rapidly increased (serum and brain) concomitant with reduced water intake in early hypoxia. Also, the nuclear expression of c-Fos, a marker for neuronal activation, related to water-consumption (SFO and MnPO) was inhibited. These effects were mitigated by a scavenger, rat adropin neutralizing antibody, which effectively neutralized adropin under hypoxia. Interestingly, injection of recombinant adropin in the third ventricle of the rats also triggered anti-dipsogenic effects and reduced c-Fos positive cells in SFO, but these effects were absent when TRPV4 was knocked down by shRNA. Moreover, adropin-activated CamKK-AMPK signaling related to TRPV4 calcium channel in SFO in normoxia. These results revealed that dissociative adropin was elevated in acute hypoxia, which was responsible for anti-dipsogenic effects by altering TRPV4-CamKK-AMPK signaling in SFO.