Translation and psychometric properties of the Hebrew version of Patient Enablement Instrument for Back Pain (PEI-BP).

BACKGROUND: Low back pain (LBP) is a widespread cause of disability worldwide. Self-management is a significant factor impacting an individual's ability to cope with LBP. The Patient Enablement Instrument for Back Pain (PEI-BP) assesses the ability of people with LBP to self-manage their illness. OBJECTIVE: This study aimed to translate and culturally adapt the PEI-BP into Hebrew and evaluate the reliability, validity, and responsiveness. DESIGN: Cross-sectional study with a nested prospective sub-sample. METHODS: The PEI-BP was translated and culturally adapted into Hebrew using recommended guidelines. We included 188 LBP patients. The psychometric properties of the PEI-BP were evaluated according to the COSMIN methodology. For construct validity, the Ronald Morris disability questionnaire, the Brief Illness Perception Questionnaire, the Fear-Avoidance Beliefs Questionnaire-physical activity, the 12-item Short-Form Health Survey mental health, and the Numerical pain rating scale were included. To assess reliability, a sub-sample of participants (n = 50) completed the PEI-BP again after one week and after six weeks (n = 50) to evaluate responsiveness. RESULTS: The PEI-BP demonstrated good internal consistency (Cronbach's α = 0.821) and test-retest reliability (ICC = 0.77). For construct validity, four out of the five hypothesized correlations were confirmed. Responsiveness showed a Receiver Operating Characteristic curve area of 0.81 (95% CI 0.67-0.93); the minimal detectable change was 14.5. A potential significant ceiling but no floor effects were observed (17.5% and 6.4%, respectively). CONCLUSIONS: The translation and validation of the PEI-BP suggest that it is a feasible, reliable, valid, and responsive instrument for evaluating 'patient enablement' with LBP in the Hebrew-speaking population.

Modulation of gill surface area does not correlate with oxygen loss in Chitala ornata.

Air-breathing fish risk losing aerially sourced oxygen to ambient hypoxic water since oxygenated blood from the air-breathing organ returns through the heart to the branchial basket before distribution. This loss is thought to help drive the evolutionary reduction in gill size with the advent of air-breathing. In many teleost fish, gill size is known to be highly plastic by modulation of their anatomic diffusion factor (ADF) with inter-lamellar cell mass (ILCM). In the anoxia-tolerant crucian carp, ILCM recedes with hypoxia but regrows in anoxia. The air-breathing teleost Chitala ornata has been shown to increase gill ADF from normoxic to mildly hypoxic water by reducing ILCM. Here, we test the hypothesis that ADF is modulated to minimize oxygen loss in severe aquatic hypoxia by measuring ADF, gas-exchange, and by using computed tomography scans to reveal possible trans-branchial shunt vessels. Contrary to our hypothesis, ADF does not modulate to prevent oxygen loss and despite no evident trans-branchial shunting, C. ornata loses only 3% of its aerially sourced O2 while still excreting 79% of its CO2 production to the severely hypoxic water. We propose this is achieved by ventilatory control and by compensating the minor oxygen loss by extra aerial O2 uptake.

Content validity of patient-reported measures evaluating experiences of the quality of transitions in healthcare settings-a scoping review.

No reviews so far have been conducted to define the constructs of patient-experienced quality in healthcare transitions or to identify existing generic measures of patients' experience of the quality within healthcare transitions. Our aim was to identify domains relevant for people experiencing healthcare transitions when evaluating the quality of care they have received, map the comprehensiveness of existing patient-reported experience measures (PREM), and evaluate the PREMs' content validity. The method was guided by the Joanna Briggs Institutes' guidance for scoping reviews. The search was performed on 07 December 2021 and updated 27 May 2024, in the electronic databases Medline (Ovid), Embase (Ovid), and Cinahl (EBSCO). The search identified 20,422 publications, and 190 studies were included for review. We identified 30 PREMs assessing at least one aspect of adults' experience of transitions in healthcare. Summarising the content, we consider a model with two domains, organisational and human-relational, likely to be adequate. However, a more comprehensive analysis and adequate definition of the construct is needed. None of the PREMs were considered content valid.

Interactive three-dimensional atlas of the mineralized skeleton of the sand tiger shark Carcharias taurus.

Non-invasive computed tomography (CT) of an adult sand tiger shark Carcharias taurus Rafinesque, 1810 is used to provide an interactive three-dimensional 'general' shark (Selachimorpha) anatomy atlas. Given its post-cranial body morphology, the sand tiger shark appeared to be a well-chosen candidate and through comparison of the sand tiger shark with several other representatives of all eight established orders of sharks, we confirm that the relatively large degree of mineralization of the endoskeleton, along with the overall size, makes the sand tiger shark an ideal candidate for skeletal segmentation and construction of a skeletal atlas using conventional CT. This atlas both increases accessibility to the internal morphological features of the sand tiger shark and provides a more generalized overview of the skeletal anatomy of sharks and can aid as a supplement to destructive fresh dissection of specimens in the future and the construction of future skeletal atlases of other less mineralized sharks.

Developing and assessing the measurement properties of an instrument to assess the impact of musculoskeletal pain in children aged 9 to 12-the pediatric musculoskeletal pain impact summary score.

BACKGROUND: Despite the high prevalence of musculoskeletal (MSK) pain in children, there is a lack of instruments to measure the impact of MSK pain on children's activity and participation. OBJECTIVE: To assess the reliability and construct validity of the Pediatric MSK Pain Impact summary score in school children (aged 9 to 12) with MSK pain. METHODS: We used a pragmatic approach in a reflective framework to assess internal consistency, structural validity, convergent validity, and discriminative validity in a sample of 615 children with MSK pain. RESULTS: The confirmatory factor analysis results indicate that the summary score has limited internal consistency and construct validity. The estimated Cronbach's alpha was 0.63, and most goodness of fit indices met the recommended thresholds (SRMR = 0.030; GFI = 0.993, CFI = 0.955, RMSEA 0.073), although they were close to the lower bounds of the thresholds. The convergent validity showed appropriate correlation of the summary score with quality of life (r = -0.33), care-seeking (r = 0.45), and medication intake (r = 0.37). Discriminative validity showed that the instrument can discriminate between the impact of pain on children with frequent and infrequent (2.93; 95% CI: 2.36 - 3.50) MSK pain. CONCLUSION: The Pediatric MSK Pain Impact summary showed limited internal consistency and construct validity; however, it can discriminate between children with frequent and infrequent pain. The results are promising for clinical and research practices as it is a short and convenient tool to be used in school-aged children.

The validity of instruments to measure knowledge in population-based cancer screening targeting individuals at average risk - A systematic review.

OBJECTIVES: Relevant knowledge is essential for informed choices about (non)participation in population-based cancer screening. Many instruments have been proposed to assess residents' knowledge about cancer screening programmes but their measurement properties are unknown. This systematic review aims to identify and critically evaluate the measurement properties of instruments to measure knowledge about cancer screening in individuals eligible for population-based screening. METHODS: A literature search was undertaken in PubMed, PsycINFO, Embase, CINAHL, Scopus and Web of Science in August 2023. The review included any study reporting one or more measurement properties of the questionnaire or sub-scale used measuring knowledge of cancer screening including breast, colorectal and/or cervical cancer screening. Studies including males aged 45 or older and females aged 20 or older were included. Two independent reviewers screened the articles and assessed the included articles using the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN). RESULTS: We included 24 instruments, which varied in number and characteristics of items. All instruments were assessed as having an inadequate instrument development. The results of structural validity, internal consistency, criterion validity and reliability were assessed as indeterminate, while construct validity and responsiveness were assessed as sufficient. CONCLUSION: This systematic review identified no instruments to measure knowledge about cancer screening where the measurement properties were sufficiently evaluated. There is a lack of focus on content validity and structural validity, and further validation of the instruments is needed. The results indicate a lack of shared understanding or agreement of what constitutes relevant knowledge about cancer screening.

Structural validity of the 5-item World Health Organization Well-being Index (WHO-5) in patients with schizophrenia spectrum disorders.

BACKGROUND: When monitoring the severity and impact of schizophrenia spectrum disorders, a measure of subjective well-being should ideally accompany measures of symptom severity and medication side effects. The self-reported 5-item World Health Organization Well-being Index (WHO-5) is a brief, generic, and widely used measure of subjective well-being. However, the structural validity of the WHO-5, namely, whether the individual item scores can be combined to produce a meaningful total score, has not been examined among patients with schizophrenia spectrum disorders. METHOD: Utilizing data from 399 Danish patients with schizophrenia spectrum disorders attending the Psychiatric Services of the Central Denmark Region, we employed Rasch analysis to examine the structural validity (i.e., unidimensionality, overall fit to the Rasch model, and differential item functioning) of the WHO-5. RESULTS: The WHO-5 was found to be unidimensional with no differential item functioning for age, sex, or inpatient/outpatient status. However, in the initial analysis, some misfit to the Rasch model, partially caused by the disordering of response categories, was evident. In adjusted analyses in which the item response categories 2 (Less than half of the time) and 3 (More than half of the time) were merged, overall fit to the model was improved. CONCLUSIONS: When two item response categories were merged, the Danish version of the WHO-5 was found to be structurally valid for patients with schizophrenia spectrum disorders. This suggests that the WHO-5 holds promise as a measure of subjective well-being in this patient population.

Trabeculations of the porcine and human cardiac ventricles are different in number but similar in total volume.

An intricate meshwork of trabeculations lines the luminal side of cardiac ventricles. Compaction, a developmental process, is thought to reduce trabeculations by adding them to the neighboring compact wall which is then enlarged. When pig, a plausible cardiac donor for xenotransplantation, is compared to human, the ventricular walls appear to have fewer trabeculations. We hypothesized the trabecular volume is proportionally smaller in pig than in human. Macroscopically, we observed in 16 pig hearts that the ventricular walls harbor few but large trabeculations. Close inspection revealed a high number of tiny trabeculations, a few hundred, within the recesses of the large trabeculations. While tiny, these were still larger than embryonic trabeculations and even when considering their number, the total tally of trabeculations in pig was much fewer than in human. Volumetrics based on high-resolution MRI of additional six pig hearts compared to six human hearts, revealed the left ventricles were not significantly differently trabeculated (21.5 versus 22.8%, respectively), and the porcine right ventricles were only slightly less trabeculated (42.1 vs 49.3%, respectively). We then analyzed volumetrically 10 pig embryonic hearts from gestational day 14-35. The trabecular and compact layer always grew, as did the intertrabecular recesses, in contrast to what compaction predicts. The proportions of the trabecular and compact layers changed substantially, nonetheless, due to differences in their growth rate rather than compaction. In conclusion, processes that affect the trabecular morphology do not necessarily affect the proportion of trabecular-to-compact myocardium and they are then distinct from compaction.

Quality in care requires kindness and flexibility - a hermeneutic-phenomenological study of patients' experiences from pathways including transitions across healthcare settings.

BACKGROUND: The number of people living with chronic conditions is increasing worldwide, and with that, the need for multiple long-term complex care across care settings. Undergoing transitions across healthcare settings is both challenging and perilous for patients. Nevertheless, knowledge of what facilitates quality during transitions in healthcare settings from the lifeworld perspective of patients is still lacking. Therefore, we aimed to explore the lived experience in healthcare quality for Danish adult patients during healthcare pathways including transitions across settings. METHODS: Within a hermeneutic-phenomenological approach, interviews were conducted with three women and five men with various diagnoses and care paths between 30 and 75 years of age. Data underwent a three phased thematic analysis leading to three themes. RESULTS: Patients with various illnesses' experiences of quality of care is described in the themes being powerless in the face of illness; burdensome access and navigation; and being in need of mercy and striving for kindness. This highlights that patients' experiences of quality in healthcare pathways across settings interweaves with an overall understanding of being powerless at the initial encounter. Access and navigation are burdensome, and system inflexibility adds to the burden and enhances powerlessness. However, caring care provided through the kindness of healthcare professionals supports patients in regaining control of their condition. CONCLUSIONS: This hermeneutical-phenomenological study sheds light on the lived experiences of people who are at various stages in their care paths with transitions across healthcare settings. Although our findings are based on the lived experiences of 8 people in a Danish context, in light of the discussion with nursing theory and other research, the results can be reflected in two main aspects: I) kind and merciful professional relationships and II) system flexibility including access and navigation, were essential for their experiences of care quality during healthcare transitions. This is important knowledge when striving to provide patients with a clear voice regarding quality in care pathways stretching across settings.

Assessing Work Functioning in Patients with Persistent Low Back Pain: Exploring the Structural Validity of the Work Rehabilitation Questionnaire.

PURPOSE: Assessing work functioning in patients with persistent low back pain (LBP) is important for understanding their ability to engage in work-related activities. This study aims to evaluate the item characteristics, factor structure, and internal consistency of the Work Rehabilitation Questionnaire (WORQ) in patients with persistent LBP. METHODS: Four hundred and twenty-five individuals with LBP completed the WORQ. Item characteristics, exploratory factor analysis (EFA), and consistency were performed to identify the underlying factors. RESULTS: Missing responses were < 2% for each item. The analysis revealed three factors: psychological wellbeing, physical functioning, and cognitive ability. The factors demonstrated strong internal consistency, with Cronbach's alpha values ranging from 0.88 to 0.93 and McDonald's Omega from 0.92 to 0.96. Fifteen items did not fit into any identified factors, suggesting their potential value in screening functioning levels beyond the factors. CONCLUSIONS: The WORQ is a valid instrument for evaluating work limitations in individuals with persistent LBP. Further research should assess its responsiveness to changes from interventions that target workability. Advancing this knowledge has the potential to promote work rehabilitation and improve the quality of life for patients with persistent LBP.

Do air-breathing fish suffer branchial oxygen loss in hypoxic water?

In hypoxia, air-breathing fish obtain O2 from the air but continue to excrete CO2 into the water. Consequently, it is believed that some O2 obtained by air-breathing is lost at the gills in hypoxic water. Pangasionodon hypophthalmus is an air-breathing catfish with very large gills from the Mekong River basin where it is cultured in hypoxic ponds. To understand how P. hypophthalmus can maintain high growth in hypoxia with the presumed O2 loss, we quantified respiratory gas exchange in air and water. In severe hypoxia (PO2: ≈ 1.5 mmHg), it lost a mere 4.9% of its aerial O2 uptake, while maintaining aquatic CO2 excretion at 91% of the total. Further, even small elevations in water PO2 rapidly reduced this minor loss. Charting the cardiovascular bauplan across the branchial basket showed four ventral aortas leaving the bulbus arteriosus, with the first and second gill arches draining into the dorsal aorta while the third and fourth gill arches drain into the coeliacomesenteric artery supplying the gut and the highly trabeculated respiratory swim-bladder. Substantial flow changes across these two arterial systems from normoxic to hypoxic water were not found. We conclude that the proposed branchial oxygen loss in air-breathing fish is likely only a minor inefficiency.

Continuous anesthesia for 60 days in an isosmotic environment does not impair limb or cardiac regeneration in the axolotl.

Longitudinal animal experiments in the field of regenerative biology often require repeated use of short-term anesthesia (minutes to a few hours). Regain of consciousness limits the level of acceptable invasiveness of procedures, and it makes it difficult to untangle behavioral changes caused by injury to physiological processes involved in the regenerative response. Therefore, a method to keep a regenerative research animal in a comatose state under continuous anesthesia during regenerative experiments often spanning months, would be ethically and experimentally desirable. Here we report on a method using propofol based anesthesia in an isosmotic environment that allows for continuous anesthesia of regenerating axolotls for 60 days with a 75% survival rate, thus spanning the majority of a full regenerative cycle following limb amputation or cryoinjury to the heart. No differences were detected in the axolotl's ability to regenerate amputated limbs and cardiac cryo-injury while anesthetized, however some regenerative failures in the limb were observed in both anesthetized and unanesthetized control groups, most likely caused by prolonged fasting. Sixty days of anesthesia may be approaching a level were kidney function is affected, but the 75% surviving anesthetized animals recovered well after anesthesia and showed a full behavioral recovery within 17 days.

Special Challenges in PET Imaging of Ectothermic Vertebrates.

The bulk of biomedical positron emission tomography (PET)-scanning experiments are performed on mammals (ie, rodents, pigs, and dogs), and the technique is only infrequently applied to answer research questions in ectothermic vertebrates such as fish, amphibians, and reptiles. Nevertheless, many unique and interesting physiological characteristics in these ectothermic vertebrates could be addressed in detail through PET. The low metabolic rate of ectothermic animals, however, may compromise the validity of physiological and biochemical parameters derived from the images created by PET and other scanning modalities. Here, we review some of the considerations that should be taken into account when PET scanning fish, amphibians, and reptiles. We present specific results from our own experiments, many of which remain previously unpublished, and we draw on examples from the literature. We conclude that knowledge on the natural history and physiology of the species studied and an understanding of the limitations of the PET scanning techniques are necessary to avoid the design of faulty experiments and erroneous conclusions.

Comment on "Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte".

Trinajstic et al., (Science, 16 September 2022, p. 1311-1314) describe exceptionally well-preserved organs in fossilized Devonian placoderms to infer the early evolution of the vertebrate heart. We argue that the report has numerous shortcomings and examples of mixed specimen codes. Further, we question whether there indeed is any evidence for a mineralized chambered heart in these placoderms.

Development of the Young Disability Questionnaire (spine) for children with spinal pain: field testing in Danish school children.

OBJECTIVE: The objective of this study was to finalise the development of the Young Disability Questionnaire (YDQ-spine) to measure the consequences of neck, midback and low back pain, relevant for schoolchildren aged 9-12 years. DESIGN: A cross-sectional field test of the YDQ-spine was carried out. SETTING: Danish primary schools. PARTICIPANTS: Children aged 9-12 years from all Danish schools were invited to complete the questionnaire. METHODS: Eight hundred and seventy-three schools were invited to participate. Consenting schools received information material, instructions and a link to an electronic version of the prefinal YDQ-spine. Local teachers distributed the electronic YDQ-spine to children aged 9-12 years. Descriptive statistics and item characteristics were carried out. Item reduction was performed using partial interitem correlations (scrutinising correlations>0.3) and factor analyses (items loading>0.3 were retained) to eliminate redundant items and to obtain insight into the structure of the questionnaire. RESULTS: A total of 768 children from 20 schools answered of the questionnaire and 280 fulfilled the inclusion criteria of having back and/or neck pain (36%). Multisite pain was reported by 38%. Partial interitem correlations and factor analyses resulted in elimination of four items which were considered redundant leaving 24 items in the final YDQ-spine with an optional section on what matters most to the child. The factor analyses showed a two-factor structure with a physical component (13 items) and a psychosocial component (10 items) in addition to one standalone item (sleep). CONCLUSION: The YDQ-spine is a novel questionnaire with satisfactory content validity measuring physical and psychosocial components (including sleep disturbances) of spinal pain in children aged 9-12 years. It also offers an optional section on what matters most to the child allowing targeted care in clinical practice.

The GLA:D BACK self-management adherence and competence checklist (SMAC Checklist)-Development, content validity and feasibility.

OBJECTIVES: To unpack the complexity and impact of self-management interventions targeting musculoskeletal health conditions, we need to learn more about treatment delivery in clinical settings. Fidelity evaluation can illuminate how complex treatments are delivered and help understand the elements that lead to the effect. The objective of this study was to develop a checklist for the evaluation of the clinicians' delivery of structured patient education and exercise intervention for people with persistent back pain, the GLA:D Back intervention. The intent was to provide a checklist adaptable for the general delivery of self-management interventions for musculoskeletal pain. METHODS: We derived items for the treatment delivery fidelity checklist from behaviour change techniques and theory about communication style. We applied a three-step developmental process covering developing a preliminary fidelity intervention framework, validating checklist content and piloting and refining the checklist. RESULTS: We developed the adaptable fidelity checklist, The GLA:D BACK Self-management Adherence and Competence Checklist (SMAC Checklist). Evaluation of clinical practice using the checklist was feasible and acceptable by clinicians. Preliminary results indicate satisfactory observer agreement during pilot testing of the checklist. CONCLUSION: The GLA:D BACK Self-management Adherence and Competence Checklist is a fidelity measurement tool for the assessment of the delivery of a self-management supportive intervention for people with persistent back pain. The intention is that it can be useful as an adaptable tool for use across self-management interventions for musculoskeletal pain.

Validity and reliability of the Danish version of QUALIDEM.

INTRODUCTION: QUALIDEM is a dementia-specific QoL instrument that allows a proxy-based Quality of Life rating in all stages of dementia. It was originally developed in The Netherlands and has later been translated into English and German. This study endeavoured to translate, cross-culturally adapt and test important psychometric properties of a Danish version in a cross-sectional validation study with a nested test-retest design. METHOD: All items underwent forward and backward translation by bilingual academics. Persons with dementia were recruited from 28 healthcare units in a Danish municipality. The severity of dementia was determined using a pragmatic approach allowing the site team to trichotomise the disease (mild, moderate-severe and very severe) before scoring the QUALIDEM. Psychometric properties for QUALIDEM were determined for item characteristics, construct validity, internal consistency, test-retest reliability, measurement error and floor and ceiling effects. The study was approved by The Danish Data Protection Agency. RESULTS: A total of 169 persons with dementia, aged 51-103, were included. The construct validity testing showed that the overall proportion of correctly hypothesised correlations was 83%. Testing for internal consistency, Cronbach's α ranged from 0.65 to 0.85 in mild-severe dementia with three out of nine subscales having values below 0.7. For very severe dementia, Cronbach's α ranged from 0.44 to 0.81, with three out of six subscales having insufficient values. For test-retest reliability, the intra-class correlation coefficients ranged from 0.56 to 0.86. The 'scale width' method revealed a marked ceiling effect in all subscales ranging from 30.6% to 87.7%. DISCUSSION: The QUALIDEM was successfully translated and cross-culturally adapted into Danish. Most subscales show acceptable internal consistency and test-retest reliability. However, a substantial measurement error and ceiling effect was present in most subscales. CONCLUSION: With few exceptions, the subscales of the Danish version of QUALIDEM have acceptable validity and reliability. Future research should address the limitations of the ceiling effects.

Heterochronic maturation of anatomical plugs for protecting the airway in rorqual whales (Balaenopteridae).

Recently, a unique mechanism for protecting the airway during lunge feeding was discovered in rorqual whales (Balaenopteridae). This mechanism is based on an oral plug structure in the soft palate with similarities in musculo-fatty composition to the nasal plugs protecting the respiratory tract of rorquals from water entry and barotrauma during diving. As a follow-up, we present here a developmental series on fetal, prenatal, juvenile and adult specimens across five species of rorquals, showing differential maturation of the nasal and oral respiratory protection plugs. Nasal plugs are fully formed to serve an immediate crucial function at birth. By contrast, the soft palate remains muscular until the onset of solid food intake, where a musculo-fatty oral plug is developed.

Test-retest reliability and agreement of lower-extremity kinematics captured in squatting and jumping preschool children using markerless motion capture technology.

The clinimetric properties of new technology should be evaluated in relevant populations before its implementation in research or clinical practice. Markerless motion capture is a new digital technology that allows for data collection in young children without some drawbacks commonly encountered with traditional systems. However, important properties, such as test-retest reliability, of this new technology have so far not been investigated. We recorded 63 preschool children using markerless motion capture (The Captury GmbH, Saarbrüken, Germany) while they performed squats and standing broad jumps. A retest session was conducted after 1 week. Recordings from the test session were processed twice to estimate the software-driven instrumental variability. Recordings from the first and second test sessions were compared to evaluate the week-to-week test-retest reliability. Statistical tests included 95% limits of agreement and intraclass correlations of absolute agreement (ICC). Jump length performance and four kinematic variables demonstrated acceptable instrumental variability (ICC > 0.76). The week-to-week reliability was excellent for jump length performance (ICC = 0.90) but poor to moderate (ICC < 0.55) for the kinematic variables. Our results indicate that preschool children exhibit considerable intra-individual kinematic variation from week-to-week during jump landings and squats. Consequently, we suggest that future work should explore individuals with persistent extreme kinematics over multiple test-sessions.

Opportunities and short-comings of the axolotl salamander heart as a model system of human single ventricle and excessive trabeculation.

Few experimental model systems are available for the rare congenital heart diseases of double inlet left ventricle (DILV), a subgroup of univentricular hearts, and excessive trabeculation (ET), or noncompaction. Here, we explore the heart of the axolotl salamander (Ambystoma mexicanum, Shaw 1789) as model system of these diseases. Using micro-echocardiography, we assessed the form and function of the heart of the axolotl, an amphibian, and compared this to human DILV (n = 3). The main finding was that both in the axolotl and DILV, blood flows of disparate oxygen saturation can stay separated in a single ventricle. In the axolotl there is a solitary ventricular inlet and outlet, whereas in DILV there are two separate inlets and outlets. Axolotls had a lower resting heart rate compared to DILV (22 vs. 72 beats per minute), lower ejection fraction (47 vs. 58%), and their oxygen consumption at rest was higher than peak oxygen consumption in DILV (30 vs. 17 ml min-1 kg-1). Concerning the ventricular myocardial organization, histology showed trabeculations in ET (n = 5) are much closer to the normal human setting than to the axolotl setting. We conclude that the axolotl heart resembles some aspects of DILV and ET albeit substantial species differences exist.