The association between tobacco smoking and systolic toe pressures in active foot ulceration

Smoking may increase the risk of diabetic foot disease and ulceration. It does so by impairing glycaemic control and promoting the formation of advanced glycated end-products. Additionally, smoking is known to delay surgical wound healing and accelerate peripheral arterial disease. We aimed to determine whether toe pressures differed in smokers with a foot ulcer, when compared to non-smokers and ex-smokers, as well as ulcer outcomes at 12 months, among patients attending Blacktown Hospital High Risk Foot Service (HRFS). This study is a retrospective analysis of our prospectively collected clinic database. Eligible participants were adults attending the HRFS between June 2020 and April 2022. Participants were included if they had an ulcer, at least one systolic toe pressure reading completed at their initial visit and attended at least one follow-up visit. Participants were followed until healing, loss to follow-up or a minimum of 12 months. A total of 195 participants were included; 36 smokers, 82 ex-smokers, and 77 controls who had never smoked. Smoking status was by self-report. Current smokers were significantly younger at initial presentation (p = .002) and tended towards lower socioeconomic status (p = .067). Current smokers were significantly more likely to have ischaemic grade 3 toe pressures (< 30 mmHg) of their left foot (p = .027), suggestive of reduced perfusion. At the end of follow up period, smokers had the numerically highest rates of minor amputations. In conclusion, smokers ulcerate younger and are more likely to have grade 3 ischaemia. Collecting information about the brachial artery pressures and the time since the last cigarette may clarify any relationship between smoking and toe pressures.Trial registration: WSLHD HREC ethics approval 2111-02 and ANZCTR registration 382470. Registered on 15/09/2021.

Glutamine-mediated Modulation of XO/uric acid/NF-kB Signaling Pathway Ameliorates Intestinal I/R-induced Bacterial Translocation and Cardiorenal Inflammatory Injury

This study explored the effect of intestinal ischaemia/reperfusion (I/R) on cardiorenal tissues. The involvement of xanthine oxidase/uric acid/NF-kB signaling in intestinal I/R was also investigated. In addition, the possible protective effect of glutamine was also evaluated. Twenty-four male Wistar rats were acclimatized and then randomly assigned to four groups (n = 6); sham-operated, glutamine-treated rats (GLUT), I/R, and I/R + GLUT. The sham-operated rats were sham-operated and received 0.5 mL of distilled water, GLUT rats were sham-operated and had 1 g/kg b.w. of glutamine, I/R animals had an intestinal I/R procedure and received 0.5 mL of distilled water, and the I/R + GLUT rats had an intestinal I/R procedure and also received 1 g/kg b.w. of glutamine. Treatments were daily and per os. Glutamine attenuated intestinal I/R-induced rise in intestinal and cardiorenal activities of creatinine kinase and lactate dehydrogenase and lactate level. More so, glutamine alleviated I/R-induced rise in malondialdehyde, xanthine oxidase, uric acid, myeloperoxidase, NF-kB, TNF-α, IL-1β, caspase 3 activity, and DNA fragmentation. Furthermore, glutamine suppressed I/R-induced decline in GSH levels and SOD and catalase activities. Moreover, glutamine improved intestinal, cardiac, and renal histology in animals subjected to intestinal I/R.

Supervised Exercise Therapy for Intermittent Claudication: A Propensity Score Matched Analysis of Retrospective Data on Long Term Cardiovascular Outcomes

OBJECTIVE

This study aimed to explore the long term outcomes of patients with intermittent claudication (IC) who completed supervised exercise therapy (SET) vs. those who declined or prematurely discontinued SET, focusing on the incidence of chronic limb threatening ischaemia (CLTI), revascularisation, major adverse limb events (MALE), and major adverse cardiovascular events (MACE).

METHODS

A retrospective registry analysis of consecutive patients with IC who were referred for SET between March 2015 and August 2016 and followed up for a minimum of five years. Serial univariable analysis and logistic regression were performed to identify the statistically significant clinical variables that were independent predictors of each outcome measure. The resulting statistically significant variables were used to guide 1:1 propensity score matching (PSM) using the nearest neighbour method with a calliper of 0.2. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the association between SET and the outcomes of interest.

RESULTS

Two hundred and sixty-six patients were referred to SET between March 2015 and August 2016. Of these, 64 patients completed SET and 202 patients did not. After PSM, 49 patients were analysed in each cohort. The Cox proportional hazards analysis revealed a significant association between completion of SET and revascularisation requirement (HR 0.46 95% CI 0.25 - 0.84; p = .011), completion of SET and progression to CLTI (HR 0.091, 95% CI 0.04 - 0.24; p < .001), completion of SET and MACE (HR 0.52; 95% CI 0.28 - 0.99; p = .05) and completion of SET and MALE (HR 0.28, 95% CI 0.13 - 0.65; p = .003). The Harrell's C index for all of these models was greater than 0.75, indicating good predictive accuracy.

CONCLUSION

Completion of SET is associated with better outcomes in patients who completed SET compared with patients who declined or discontinued SET with respect to clinically important cardiovascular outcomes over seven years.

Correlates and consequences of atrial fibrillation in a prospective study of 25 000 participants in the China Kadoorie Biobank

Aims

The prevalence of atrial fibrillation (AF) is positively correlated with prior cardiovascular diseases (CVD) and CVD risk factors but is lower in Chinese than Europeans despite their higher burden of CVD. We examined the prevalence and prognosis of AF and other electrocardiogram (ECG) abnormalities in the China Kadoorie Biobank.

Methods and results

A random sample of 25 239 adults (mean age 59.5 years, 62% women) had a 12-lead ECG recorded and interpreted using a Mortara VERITAS™ algorithm in 2013-14. Participants were followed up for 5 years for incident stroke, ischaemic heart disease, heart failure (HF), and all CVD, overall and by CHA2DS2-VASc scores, age, sex, and area. Overall, 1.2% had AF, 13.6% had left ventricular hypertrophy (LVH), and 28.1% had ischaemia (two-thirds of AF cases also had ischaemia or LVH). The prevalence of AF increased with age, prior CVD, and levels of CHA₂DS₂-VASc scores (0.5%, 1.3%, 2.1%, 2.9%, and 4.4% for scores <2, 2, 3, 4, and ≥5, respectively). Atrial fibrillation was associated with two-fold higher hazard ratios (HR) for CVD (2.15; 95% CI, 1.71-2.69) and stroke (1.88; 1.44-2.47) and a four-fold higher HR for HF (3.79; 2.21-6.49). The 5-year cumulative incidence of CVD was comparable for AF, prior CVD, and CHA₂DS₂-VASc scores ≥ 2 (36.7% vs. 36.2% vs. 37.7%, respectively) but was two-fold greater than for ischaemia (19.4%), LVH (18.0%), or normal ECG (14.1%), respectively.

Conclusion

The findings highlight the importance of screening for AF together with estimation of CHA₂DS₂-VASc scores for prevention of CVD in Chinese adults.

Efficacy of propofol-supplemented cardioplegia on biomarkers of organ injury in patients having cardiac surgery using cardiopulmonary bypass: a statistical analysis plan for the ProMPT-2 randomised controlled trial

BACKGROUND

The ProMPT-2 trial (Propofol for Myocardial Protection Trial #2) aims to compare the safety and efficacy of low- and high-dose propofol supplementation of the cardioplegia solution during adult cardiac surgery versus sham supplementation. This update presents the statistical analysis plan, detailing how the trial data will be analysed and presented. Outlined analyses are in line with the Consolidated Standards of Reporting Trials and the statistical analysis plan has been written prior to database lock and the final analysis of trial data to avoid reporting bias (following recommendations from the International Conference on Harmonisation of Good Clinical Practice).

METHODS/DESIGN

ProMPT-2 is a multi-centre, blinded, parallel three-group randomised controlled trial aiming to recruit 240 participants from UK cardiac surgery centres to either sham cardioplegia supplementation, low dose (6 µg/ml) or high dose (12 µg/ml) propofol cardioplegia supplementation. The primary outcome is cardiac-specific troponin T levels (a biomarker of cardiac injury) measured during the first 48 h following surgery. The statistical analysis plan describes the planned analyses of the trial primary and secondary outcomes in detail, including approaches to deal with missing data, multiple testing, violation of model assumptions, withdrawals from the trial, non-adherence with the treatment and other protocol deviations. It also outlines the planned sensitivity analyses and exploratory analyses to be performed.

DISCUSSION

This manuscript prospectively describes, prior to the completion of data collection and database lock, the analyses to be undertaken for the ProMPT-2 trial to reduce risk of reporting and data-driven analyses.

TRIAL REGISTRATION

ISRCTN ISRCTN15255199. Registered on 26 March 2019.

Electrophysiological mechanisms underlying T wave pseudonormalisation on stress ECGs in hypertrophic cardiomyopathy

BACKGROUND

Pseudonormal T waves may be detected on stress electrocardiograms (ECGs) in hypertrophic cardiomyopathy (HCM). Either myocardial ischaemia or purely exercise-induced changes have been hypothesised to contribute to this phenomenon, but the precise electrophysiological mechanisms remain unknown.

METHODS

Computational models of human HCM ventricles (n = 20) with apical and asymmetric septal hypertrophy phenotypes with variable severities of repolarisation impairment were used to investigate the effects of acute myocardial ischaemia on ECGs with T wave inversions at baseline. Virtual 12-lead ECGs were derived from a total of 520 biventricular simulations, for cases with regionally ischaemic K+ accumulation in hypertrophied segments, global exercise-induced serum K+ increases, and/or increased pacing frequency, to analyse effects on ECG biomarkers including ST segments, T wave amplitudes, and QT intervals.

RESULTS

Regional ischaemic K+ accumulation had a greater impact on T wave pseudonormalisation than exercise-induced serum K+ increases, due to larger reductions in repolarisation gradients. Increases in serum K+ and pacing rate partially corrected T waves in some anatomical and electrophysiological phenotypes. T wave morphology was more sensitive than ST segment elevation to regional K+ increases, suggesting that T wave pseudonormalisation may sometimes be an early, or the only, ECG feature of myocardial ischaemia in HCM.

CONCLUSIONS

Ischaemia-induced T wave pseudonormalisation can occur on stress ECG testing in HCM before significant ST segment changes. Some anatomical and electrophysiological phenotypes may enable T wave pseudonormalisation due to exercise-induced increased serum K+ and pacing rate. Consideration of dynamic T wave abnormalities could improve the detection of myocardial ischaemia in HCM.

Critical limb-threatening ischaemia and microvascular transformation: clinical implications

BACKGROUND AND AIMS

Clinical management of critical limb-threatening ischaemia (CLTI) is focused on prevention and treatment of atherosclerotic arterial occlusions. The role of microvascular pathology in disease progression is still largely unspecified and more importantly not utilized for treatment. The aim of this explorative study was to characterize the role of the microvasculature in CLTI pathology.

METHODS

Clinical high-resolution imaging of CLTI patients (n = 50) and muscle samples from amputated CLTI limbs (n = 40) were used to describe microvascular pathology of CLTI at the level of resting muscle blood flow and microvascular structure, respectively. Furthermore, a chronic, low arterial driving pressure-simulating ischaemia model in rabbits (n = 24) was used together with adenoviral vascular endothelial growth factor A gene transfers to study the effect of microvascular alterations on muscle outcome.

RESULTS

Resting microvascular blood flow was not depleted but displayed decreased capillary transit time (P < .01) in CLTI muscles. Critical limb-threatening ischaemia muscle microvasculature also exhibited capillary enlargement (P < .001) and further arterialization along worsening of myofibre atrophy and detaching of capillaries from myofibres. Furthermore, CLTI-like capillary transformation was shown to worsen calf muscle force production (P < .05) and tissue outcome (P < .01) under chronic ischaemia in rabbits and in healthy, normal rabbit muscle.

CONCLUSIONS

These findings depict a progressive, hypoxia-driven transformation of the microvasculature in CLTI muscles, which pathologically alters blood flow dynamics and aggravates tissue damage under low arterial driving pressure. Hypoxia-driven capillary enlargement can be highly important for CLTI outcomes and should therefore be considered in further development of diagnostics and treatment of CLTI.

Arterial Blood Flow and Effects on Limb Tissue Perfusion During Endoshunting of the Common Iliac Artery in an Experimental Porcine Model

Objective

Temporary arterial shunting is an established method to prevent tissue ischaemia. Although less well established, shunting might also be achieved through endovascular and hybrid techniques, known as endoshunting. Endoshunting offers advantages, for example, enabling minimally invasive access and avoiding complete occlusion of the donor artery. In an ex vivo bench test, volume flow in various interconnected endoshunt systems has been tested previously. This study aimed to investigate the capacity of the best performing endoshunt system in vivo.

Methods

Six anaesthetised pigs had their common iliac arteries (CIAs) explored, with the left CIA serving as the experimental and the right CIA as the control. Mean arterial pressure, regional blood flow, endoshunt flow, and regional oxygen extraction and lactate production were recorded. Distal muscle perfusion was monitored using near infrared spectroscopy (NIRS). Each experiment involved baseline registration, cross clamping of the left CIA, a 120 minute endoshunt session, and restoration of native flow.

Results

During cross clamping, NIRS values on the experimental side reached the lowest measurable value. Following endoshunt activation, there were no NIRS value differences between the experimental and control extremities whereas the average arterial flow decreased in both the experimental (270-140 mL/min, p = .028) and control extremities (245-190 mL/min, p = .25), with a greater drop on the endoshunted side (48% vs. 22%, respectively). Lactate levels temporarily increased by 42% in the endoshunted limb on endoshunt activation but were normalised within an hour. Oxygen extraction remained constant at 55% on the control side but increased to 70% on the endoshunted side (p = .068).

Conclusion

In this animal model, a flow optimised endoshunt system appeared to provide sufficient blood flow and restored stable tissue perfusion. Although arterial flow was slightly lower and oxygen extraction slightly higher on the endoshunted side, the endoshunt seemed to deliver adequate perfusion to prevent significant ischaemia.

Myocardial perfusion in cardiac amyloidosis

AIMS

Cardiac involvement is the main driver of clinical outcomes in systemic amyloidosis and preliminary studies support the hypothesis that myocardial ischaemia contributes to cellular damage. The aims of this study were to assess the presence and mechanisms of myocardial ischaemia using cardiovascular magnetic resonance (CMR) with multiparametric mapping and histopathological assessment.

METHODS AND RESULTS

Ninety-three patients with cardiac amyloidosis (CA) (light-chain amyloidosis n = 42, transthyretin amyloidosis n = 51) and 97 without CA (three-vessel coronary disease [3VD] n = 47, unobstructed coronary arteries n = 26, healthy volunteers [HV] n = 24) underwent quantitative stress perfusion CMR with myocardial blood flow (MBF) mapping. Twenty-four myocardial biopsies and three explanted hearts with CA were analysed histopathologically. Stress MBF was severely reduced in patients with CA with lower values than patients with 3VD, unobstructed coronary arteries and HV (CA: 1.04 ± 0.51 ml/min/g, 3VD: 1.35 ± 0.50 ml/min/g, unobstructed coronary arteries: 2.92 ± 0.52 ml/min/g, HV: 2.91 ± 0.73 ml/min/g; CA vs. 3VD p = 0.011, CA vs. unobstructed coronary arteries p < 0.001, CA vs. HV p < 0.001). Myocardial perfusion abnormalities correlated with amyloid burden, systolic and diastolic function, structural parameters and blood biomarkers (p < 0.05). Biopsies demonstrated abnormal vascular endothelial growth factor staining in cardiomyocytes and endothelial cells, which may be related to hypoxia conditions. Amyloid infiltration in intramural arteries was associated with severe lumen reduction and severe reduction in capillary density.

CONCLUSION

Cardiac amyloidosis is associated with severe inducible myocardial ischaemia demonstrable by histology and CMR stress perfusion mapping. Histological evaluation indicates a complex pathophysiology, where in addition to systolic and diastolic dysfunction, amyloid infiltration of the epicardial arteries and disruption and rarefaction of the capillaries play a role in contributing to myocardial ischaemia.

Isolation of a novel isoprenylated phenolic compound and neuroprotective evaluation of Dodonaea viscosa extract against cerebral ischaemia-reperfusion injury in rats

Dodonaea viscosa grows widely in Saudi Arabia, but studies evaluating its neuroprotective activity are lacking. Thus, this study aimed to isolate and identify the secondary metabolites and evaluate the neuroprotective effects of D. viscosa leaves. The isolation and identification of phytochemicals were performed using chromatographic and spectroscopic techniques. The neuroprotective potential of the extract was evaluated against focal cerebral ischaemia-reperfusion injury in rat model. Neurobehavioural deficits in the rats were evaluated, and their brains were harvested to measure infarct volume and oxidative biomarkers. Results revealed the presence of three compounds: a novel isoprenylated phenolic derivative that was elucidated as 4-hydroxy-3-(3'-methyl-2'-butenyl) phenyl 1-O-β-D-apiosyl-(1''' → 6'')- β-D-glucopyranoside (named Viscomarfadol) and two known compounds (isorhamnetin-3-O-rutinoside and epicatechin (4-8) catechin). Pre-treatment of the rats with the extract improved neurological outcomes. It significantly reduced neurological deficits and infarct volume; significantly reduced lipid peroxidation, as evidenced by decreased malondialdehyde levels; and significantly elevated antioxidant (superoxide dismutase, catalase, and glutathione) activities. These results indicate that D. viscosa is a promising source of bioactive compounds that can improve neurological status, decrease infarct volume, and enhance antioxidant activities in rats with cerebral ischaemic injury. Thus, D. viscosa could be developed into an adjuvant therapy for ischaemic stroke and other oxidative stress-related neurodegenerative disorders. Further investigations are warranted to explore other bioactive compounds in D. viscosa and evaluate their potential neuroprotective activities.

Energy optimisation predicts the capacity of ion buffering in the brain

Neurons store energy in the ionic concentration gradients they build across their cell membrane. The amount of energy stored, and hence the work the ions can do by mixing, can be enhanced by the presence of ion buffers in extra- and intracellular space. Buffers act as sources and sinks of ions, however, and unless the buffering capacities for different ion species obey certain relationships, a complete mixing of the ions may be impeded by the physical conditions of charge neutrality and isotonicity. From these conditions, buffering capacities were calculated that enabled each ion species to mix completely. In all valid buffer distributions, the [Formula: see text] ions were buffered most, with a capacity exceeding that of [Formula: see text] and [Formula: see text] buffering by at least an order of magnitude. The similar magnitude of the (oppositely directed) [Formula: see text] and [Formula: see text] gradients made extracellular space behave as a [Formula: see text]-[Formula: see text] exchanger. Anions such as [Formula: see text] were buffered least. The great capacity of the extra- and intracellular [Formula: see text] buffers caused a large influx of [Formula: see text] ions as is typically observed during energy deprivation. These results explain many characteristics of the physiological buffer distributions but raise the question how the brain controls the capacity of its ion buffers. It is suggested that neurons and glial cells, by their great sensitivity to gradients of charge and osmolarity, respectively, sense deviations from electro-neutral and isotonic mixing, and use these signals to tune the chemical composition, and buffering capacity, of the extra- and intracellular matrices.

Adipose Derived Stromal Vascular Fraction and Mesenchymal Stem Cells Improve Angiogenesis in a Rat Hindlimb Ischaemia Model

OBJECTIVE

This study aimed to investigate the effect of human adipose tissue derived stromal vascular fraction (AD-SVF) and mesenchymal stem cells (AD-MSCs) on blood flow recovery and neovascularisation in a rat hindlimb ischaemia model.

METHODS

SVF was isolated using an automated centrifugal system, and AD-MSCs were obtained from adherent cultures of SVF cells. Rats were divided into four groups of six rats each: non-ischaemia (Group 1); saline treated ischaemia (Group 2); SVF treated ischaemia (Group 3); and AD-MSC treated ischaemia (Group 4). Unilateral hindlimb ischaemia was induced in Sprague-Dawley rats via femoral artery ligation. Saline, SVF, or AD-MSCs were injected intramuscularly into the adductor muscle intra-operatively. Cell viability was calculated as the percentage of live cells relative to total cell number. Blood flow improvement, muscle fibre injury, and angiogenic properties were validated using thermal imaging and histological assessment.

RESULTS

The viabilities of SVF and AD-MSCs were 83.3% and 96.7%, respectively. Group 1 exhibited no significant temperature difference between hindlimbs, indicating a lack of blood flow changes. The temperature gradient gradually decreased in SVF and AD-MSC treated rats compared with saline treated rats. In addition, only normal muscle fibres with peripherally located nuclei were observed in Group 1. Groups 3 and 4 exhibited significantly fewer centrally located nuclei, indicating less muscle damage compared with Group 2. Regarding angiogenic properties, CD31 staining of endothelial cells showed similar patterns among all groups, whereas expression of vascular endothelial growth factor, as a crucial angiogenesis factor, was enhanced in the SVF and AD-MSC treated groups.

CONCLUSION

SVF and AD-MSCs improved blood flow and neovascularisation in a rat hindlimb ischaemia model, suggesting their potential ability to promote angiogenesis. Further extensive research is warranted to explore their potential applications in the treatment of severe lower extremity arterial disease.

Mild hypothermia attenuates ischaemia/reperfusion injury: insights from serial non-invasive pressure-volume loops

AIMS

Mild hypothermia, 32-35°C, reduces infarct size in experimental studies, potentially mediating reperfusion injuries, but human trials have been ambiguous. To elucidate the cardioprotective mechanisms of mild hypothermia, we analysed cardiac performance in a porcine model of ischaemia/reperfusion, with serial cardiovascular magnetic resonance (CMR) imaging throughout 1 week using non-invasive pressure-volume (PV) loops.

METHODS AND RESULTS

Normothermia and Hypothermia group sessions (n = 7 + 7 pigs, non-random allocation) were imaged with Cardiovascular magnetic resonance (CMR) at baseline and subjected to 40 min of normothermic ischaemia by catheter intervention. Thereafter, the Hypothermia group was rapidly cooled (mean 34.5°C) for 5 min before reperfusion. Additional CMR sessions at 2 h, 24 h, and 7 days acquired ventricular volumes and ischaemic injuries (unblinded analysis). Stroke volume (SV: -24%; P = 0.029; Friedmans test) and ejection fraction (EF: -20%; P = 0.068) were notably reduced at 24 h in the Normothermia group compared with baseline. In contrast, the decreases were ameliorated in the Hypothermia group (SV: -6%; P = 0.77; EF: -6%; P = 0.13). Mean arterial pressure remained stable in Normothermic animals (-3%, P = 0.77) but dropped 2 h post-reperfusion in hypothermic animals (-18%, P = 0.007). Both groups experienced a decrease and partial recovery pattern for PV loop-derived variables over 1 week, but the adverse effects tended to attenuate in the Hypothermia group. Infarct sizes were 10 ± 8% in Hypothermic and 15 ± 8% in Normothermic animals (P = 0.32). Analysis of covariance at 24 h indicated that hypothermia has cardioprotective properties incremental to reducing infarct size, such as higher external power (P = 0.061) and lower arterial elastance (P = 0.015).

CONCLUSION

Using non-invasive PV loops by CMR, we observed that mild hypothermia at reperfusion alleviates the heart's work after ischaemia/reperfusion injuries during the first week and preserves short-term cardiac performance. This hypothesis-generating study suggests hypothermia to have cardioprotective properties, incremental to reducing infarct size. The primary cardioprotective mechanism was likely an afterload reduction acutely unloading the left ventricle.

Mechanisms and prognostic impact of myocardial ischaemia in hypertrophic cardiomyopathy

Despite the progress made in risk stratification, sudden cardiac death and heart failure remain dreaded complications for hypertrophic cardiomyopathy (HCM) patients. Myocardial ischaemia is widely acknowledged as a contributor to cardiovascular events, but the assessment of ischaemia is not yet included in HCM clinical guidelines. This review aims to evaluate the HCM-specific pro-ischaemic mechanisms and the potential prognostic value of imaging for myocardial ischaemia in HCM. A literature review was performed using PubMed to identify studies with non-invasive imaging of ischaemia (cardiovascular magnetic resonance, echocardiography, and nuclear imaging) in HCM, prioritising studies published after the last major review in 2009. Other studies, including invasive ischaemia assessment and post-mortem histology, were also considered for mechanistic or prognostic relevance. Pro-ischaemic mechanisms in HCM reviewed included the effects of sarcomeric mutations, microvascular remodelling, hypertrophy, extravascular compressive forces and left ventricular outflow tract obstruction. The relationship between ischaemia and fibrosis was re-appraised by considering segment-wise analyses in multimodal imaging studies. The prognostic significance of myocardial ischaemia in HCM was evaluated using longitudinal studies with composite endpoints, and reports of ischaemia-arrhythmia associations were further considered. The high prevalence of ischaemia in HCM is explained by several micro- and macrostructural pathological features, alongside mutation-associated energetic impairment. Ischaemia on imaging identifies a subgroup of HCM patients at higher risk of adverse cardiovascular outcomes. Ischaemic HCM phenotypes are a high-risk subgroup associated with more advanced left ventricular remodelling, but further studies are required to evaluate the independent prognostic value of non-invasive imaging for ischaemia.

Determinants of the maximal functional reserve during repeated supramaximal exercise by humans: The roles of Nrf2/Keap1, antioxidant proteins, muscle phenotype and oxygenation

When high-intensity exercise is performed until exhaustion a "functional reserve" (FR) or capacity to produce power at the same level or higher than reached at exhaustion exists at task failure, which could be related to reactive oxygen and nitrogen species (RONS)-sensing and counteracting mechanisms. Nonetheless, the magnitude of this FR remains unknown. Repeated bouts of supramaximal exercise at 120% of VO2max interspaced with 20s recovery periods with full ischaemia were used to determine the maximal FR. Then, we determined which muscle phenotypic features could account for the variability in functional reserve in humans. Exercise performance, cardiorespiratory variables, oxygen deficit, and brain and muscle oxygenation (near-infrared spectroscopy) were measured, and resting muscle biopsies were obtained from 43 young healthy adults (30 males). Males and females had similar aerobic (VO2max per kg of lower extremities lean mass (LLM): 166.7 ± 17.1 and 166.1 ± 15.6 ml kg LLM-1.min-1, P = 0.84) and anaerobic fitness (similar performance in the Wingate test and maximal accumulated oxygen deficit when normalized to LLM). The maximal FR was similar in males and females when normalized to LLM (1.84 ± 0.50 and 2.05 ± 0.59 kJ kg LLM-1, in males and females, respectively, P = 0.218). This FR depends on an obligatory component relying on a reserve in glycolytic capacity and a putative component generated by oxidative phosphorylation. The aerobic component depends on brain oxygenation and phenotypic features of the skeletal muscles implicated in calcium handling (SERCA1 and 2 protein expression), oxygen transport and diffusion (myoglobin) and redox regulation (Keap1). The glycolytic component can be predicted by the protein expression levels of pSer40-Nrf2, the maximal accumulated oxygen deficit and the protein expression levels of SOD1. Thus, an increased capacity to modulate the expression of antioxidant proteins involved in RONS handling and calcium homeostasis may be critical for performance during high-intensity exercise in humans.

The impact of fingolimod on Treg function in brain ischaemia

Fingolimod has generally shown neuroprotective effects in stroke models. Here, we tested the hypothesis that fingolimod modulates T-cell cytokine production towards a regulatory phenotype. Second, we investigated how fingolimod altered the Treg suppressive function and the sensitivity of effector T cells to regulation. Mice that had underwent the permanent electrocoagulation of the left middle cerebral artery received saline or fingolimod (0.5 mg/kg) daily for 10-days post-ischaemia. Fingolimod improved neurobehavioural recovery compared to saline control and increased Treg frequency in the periphery and brain. Tregs from fingolimod-treated animals had a higher expression of CCR8. Fingolimod increased the frequencies of CD4+ IL-10+ , CD4+ IFN-γ+ and CD4+ IL-10+ IFN-γ+ cells in spleen and blood, and CD4+ IL-17+ cells in the spleen, with only minor effects on CD8+ T-cell cytokine production. Treg from post-ischaemic mice had reduced suppressive function compared to Treg from non-ischaemic mice. Fingolimod treatment rescued this function against saline-treated but not fingolimod-treated CD4+ effector T cells. In conclusion, fingolimod seems to improve the suppressive function of Treg post-stroke while also increasing the resistance of CD4+ effector cells to this suppression. Fingolimod's capacity to increase both effector and regulatory functions may explain the lack of consistent improvement in functional recovery in experimental brain ischaemia.

Vascular flow limitations affecting the cervico-cranial region: Understanding ischaemia

BACKGROUND

Blood flow and brain ischaemia have been of interest to physical therapists for decades. Despite much debate, and multiple publications around risk assessment of the cervical spine, more work is required to achieve consensus on this vital, complex topic. In 2020, the International Federation of Orthopaedic Manipulative Physical Therapists (IFOMPT) Cervical Framework adopted the dubious terminology 'vascular pathologies of the neck', which is misleading, on the premise that 1) not all flow limitations leading to ischaemia, are associated with observable blood vessel pathology and 2) not all blood flow limitations leading to ischaemia, are in the anatomical region of the 'neck'.

OBJECTIVE

This paper draws upon the full body of haemodynamic knowledge and science, to describe the variety of arterial flow limitations affecting the cervico-cranial region.

DISCUSSION

It is the authors' contention that to apply clinical reasoning and appropriate risk assessment of the cervical spine, there is a requirement for clinicians to have a clear understanding of anatomy/anatomical relations, the haemodynamic science of vascular flow limitation, and related pathologies. This paper describes the wide range of presentations and haemodynamic mechanisms that clinicians may encounter in practice. In cases with a high index suspicion of vascular involvement or an adverse response to assessment/intervention, appropriate referral should be made for further investigations, using consistent terminology. The term 'vascular flow limitation' is proposed when considering the range of mechanisms at play. This fits the terminology used (in vascular literature) at other anatomical sites and is understood by medical colleagues.

Comparative effect of stenting plus medical therapy vs medical therapy alone on the risk of stroke and death in patients with symptomatic intracranial stenosis: a systematic review and meta-analysis

BACKGROUND

Recently, several randomized controlled trials (RCTs) of stenting plus medical therapy versus medical therapy alone have been successfully conducted for the treatment of patients with symptomatic intracranial stenosis. This study aimed to evaluate differences between these two therapies in the risk of stroke and death.

METHODS

MEDLINE, EMBASE, the Cochrane Library, and ClinicalTrials.gov were systematically searched to identify relevant studies published before August 24, 2022. Review Manager 5.3 software was used to assess the data. The risk ratio (RR) was analysed and calculated with a random effect model or a fixed effects model.

RESULTS

We pooled 921 participants from three RCTs. Compared to the medical therapy alone group, the stenting plus medical therapy group had a higher risk of 30-day death or stroke (RR = 2.69 [1.64-4.41], P < 0.0001, I² = 0%). When the follow-up period exceeded 1 year (≥ 1 year), there was no significant difference in the risk of stroke or death between these two groups. The subgroup analysis showed that if the time from stroke onset to implantation was extended, additional stenting would have no effect on the risk of stroke or death, whether within 30 days or within 1 year (P = 0.16 and 0.78).

CONCLUSION

Medical therapy alone has a lower risk of stroke and death in the short term than stenting plus medical therapy, while no difference exists in the long term. More studies are still needed to further explore the precision strategy of stent implantation for symptomatic intracranial stenosis patients.

Development of a model to investigate the effects of prolonged ischaemia on the muscles of mastication of male Sprague Dawley rats

OBJECTIVE

The aims of this study were to develop a novel rodent model of masticatory muscle ischaemia via unilateral ligation of the external carotid artery (ECA), and to undertake a preliminary investigation to characterize its downstream effects on mechanosensitivity and cellular features of the masseter and temporalis muscles.

DESIGN

The right ECA of 18 male Sprague-Dawley rats was ligated under general anaesthesia. Mechanical detection thresholds (MDTs) at the masseter and temporalis bilaterally were measured immediately before ECA ligation and after euthanasia at 10-, 20-, and 35-days (n = 6 rats/timepoint). Tissue samples from both muscles and sides were harvested for histological analyses and for assessing changes in the expression of markers of hypoxia and muscle degeneration (Hif-1α, VegfA, and Fbxo32) via real time PCR. Data were analyzed using mixed effect models and non-parametric tests. Statistical significance was set at p < 0.05.

RESULTS

MDTs were higher in the right than left hemiface (p = 0.009) after 20 days. Histological changes indicative of muscle degeneration and fibrosis were observed in the right muscles. Hif-1α, VegfA, and Fbxo32 were more highly expressed in the masseter than temporalis muscles (all p < 0.05). Hif-1α and, VegfA did not change significantly with time in all muscles (all p > 0.05). Fbxo32 expression gradually increased in the right masseter (p = 0.024) and left temporalis (p = 0.05).

CONCLUSIONS

ECA ligation in rats induced hyposensitivity in the homolateral hemiface after 20 days accompanied by tissue degenerative changes. Our findings support the use of this model to study pathophysiologic mechanisms of masticatory muscle ischaemia in larger investigations.

Epidemiology of heart failure in young adults: a French nationwide cohort study

AIMS

Heart failure (HF) in young adults is uncommon, and changes in its incidence and prognosis in recent years are poorly described.

METHODS AND RESULTS

The incidence and prognosis of HF in young adults (1850 years) were characterized using nationwide medico-administrative data from the French National Hospitalization Database (period 20132018). A total of 1,486 877 patients hospitalized for incident HF were identified, including 70 075 (4.7) patients aged 1850 years (estimated incidence of 0.44 for this age group). During the study period, the overall incidence of HF tended to decrease in the overall population but significantly increased by 0.041 in young adults (P 0.001). This increase was notably observed among young men (from 0.51 to 0.59, P 0.001), particularly those aged 3650 years. In these young men, ischaemic heart disease (IHD) was the most frequently reported cause of HF, whereas non-ischaemic HF was mainly observed in patients 35 years old. In contrast to non-ischaemic HF, the incidence of IHD increased over the study period, which suggests that IHD-related HF is progressively affecting younger patients. Concordantly, young HF patients presented with high rates of traditional IHD risk factors, including obesity, smoking, hypertension, dyslipidaemia, or diabetes. Lastly, the rates of re-hospitalization (for HF or for any cause) within two years after the first HF event and in-hospital mortality were high in all groups, indicating a poor-prognosis population.

CONCLUSION

Strategies for the prevention of HF risk factors should be strongly considered for patients under 50 years old.

Optimisation of Volume Flow Rates when Using Endovascular Shunting Techniques: An Experimental Study in Different Bench Flow Circuits

Objective

Acute tissue ischaemia may arise due to arterial emergencies or during more complex vascular procedures and may be mitigated by temporary shunting techniques.
Endovascular shunting (ES) techniques enable percutaneous access and shunting from the donor artery without the need to completely interrupt the arterial flow in the donor artery. An endoshunt system may also cover longer distances than most conventional shunts. The aim was to investigate and optimise the flow rates in different endovascular shunt systems.

Methods

Step 1: The flow capacity of different ES configurations was compared with the flow capacity of a 9 Fr Pruitt-Inahara shunt (PIS). An intravenous bag with 0.9% NaCl, pressurised to 90 mmHg, was connected simultaneously to a PIS and to one of the tested ES configurations. The two shunt systems were then opened at the same time.
The delivered fluid volumes from the shunt systems were collected and measured. The volume flow rate was subsequently calculated.
Steps 2 and 3: Within a heart lung machine circuit, pressure-flow charts were constructed for the individual ES components and for the fully connected optimised endoshunt systems. The flow rate was increased in steps of 40-50 mL/min while monitoring the driving pressure, enabling the creation and comparison of the pressure-flow charts for the individually tested components. In total, seven individual inflow and outflow potential ES components were investigated with inflow and outflow diameters ranging from 6 to 15 Fr.

Results

ES systems based on standard donor introducers led to substantially lower volume flow than the corresponding PIS volume flow, whereas ES systems based on dedicated 6 or 8 Fr dialysis access introducers (Prelude Short Sheet, Merit Medical) matched PIS flow rates. The introduction of 30 cm long ¼'' perfusion tubing within the ES system did not affect volume flow for any of the tested ES configurations.

Conclusion

Endoshunting techniques can match PIS volume flow rates over short and long distances. The achieved ES flow rate is highly dependent on the components used within the ES system.

Acidic environments trigger intracellular H+-sensing FAK proteins to re-balance sarcolemmal acid-base transporters and auto-regulate cardiomyocyte pH

AIMS

In cardiomyocytes, acute disturbances to intracellular pH (pHi) are promptly corrected by a system of finely tuned sarcolemmal acid-base transporters. However, these fluxes become thermodynamically re-balanced in acidic environments, which inadvertently causes their set-point pHi to fall outside the physiological range. It is unclear whether an adaptive mechanism exists to correct this thermodynamic challenge, and return pHi to normal.

METHODS AND RESULTS

Following left ventricle cryo-damage, a diffuse pattern of low extracellular pH (pHe) was detected by acid-sensing pHLIP. Despite this, pHi measured in the beating heart (13C NMR) was normal. Myocytes had adapted to their acidic environment by reducing Cl-/HCO3- exchange (CBE)-dependent acid-loading and increasing Na+/H+ exchange (NHE1)-dependent acid-extrusion, as measured by fluorescence (cSNARF1). The outcome of this adaptation on pHi is revealed as a cytoplasmic alkalinization when cells are superfused at physiological pHe. Conversely, mice given oral bicarbonate (to improve systemic buffering) had reduced myocardial NHE1 expression, consistent with a needs-dependent expression of pHi-regulatory transporters. The response to sustained acidity could be replicated in vitro using neonatal ventricular myocytes incubated at low pHe for 48 h. The adaptive increase in NHE1 and decrease in CBE activities was linked to Slc9a1 (NHE1) up-regulation and Slc4a2 (AE2) down-regulation. This response was triggered by intracellular H+ ions because it persisted in the absence of CO2/HCO3- and became ablated when acidic incubation media had lower chloride, a solution manoeuvre that reduces the extent of pHi-decrease. Pharmacological inhibition of FAK-family non-receptor kinases, previously characterized as pH-sensors, ablated this pHi autoregulation. In support of a pHi-sensing role, FAK protein Pyk2 (auto)phosphorylation was reduced within minutes of exposure to acidity, ahead of adaptive changes to pHi control.

CONCLUSIONS

Cardiomyocytes fine-tune the expression of pHi-regulators so that pHi is at least 7.0. This autoregulatory feedback mechanism defines physiological pHi and protects it during pHe vulnerabilities.

Delayed bowel necrosis due to inferior mesenteric artery occlusion in Stanford type A acute aortic dissection

Although inferior mesenteric artery occlusion due to acute aortic dissection sometimes occurs, it is usually not considered an important finding. Herein, we present an extremely rare case of delayed bowel ischaemia due to inferior mesenteric artery occlusion in Stanford type A acute aortic dissection that highlights the need for cardiac surgeons to be mindful of inferior mesenteric artery occlusion in patients with superior mesenteric artery dissection or vascular anomalies in the mesenteric arteries.

Non-hyperaemic assessment of coronary ischaemia: application of machine learning techniques

Aims

Hyperaemic and non-hyperaemic pressure ratios (NHPR) are routinely used to identify significant coronary lesions. Machine learning (ML) techniques may help better understand these indices and guide future practice. This study assessed the ability of a purpose-built ML algorithm to classify coronary ischaemia during non-hyperaemia compared with the existing gold-standard technique (fractional flow reserve, FFR). Further, it investigated whether ML could identify components of coronary and aortic pressure cycles indicative of ischaemia.

Methods and results

Seventy-seven coronary vessel lesions (39 FFR defined ischaemia, 53 patients) with proximal and distal non-hyperaemic pressure waveforms and FFR values were assessed using supervised and unsupervised learning techniques in combination with principal component analysis (PCA). Fractional flow reserve measurements were obtained from the right coronary artery (13), left anterior descending (46), left circumflex (11), left main (1), obtuse marginal (2), and diagonal (4). The most accurate supervised learning classification utilized whole-cycle aortic with diastolic distal blood pressure waveforms, yielding a classification accuracy of 86.9% (sensitivity 86.8%, specificity 87.2%, positive predictive value 86.8%, negative predictive value 87.2%). Principal component analysis showed subtle variations in coronary pressures at the start of diastole have significant relation to ischaemia, and whole-cycle aortic pressure data are important for determining ischaemia.

Conclusions

Our ML algorithm classifies significant coronary lesions with accuracy similar to previous studies comparing time-domain NHPRs with FFR. Further, it has identified characteristics of pressure waveforms that relate to function. These results provide an application of ML to ischaemia requiring only standard data from non-hyperaemic pressure measurements.

Unique collateralisation between the left internal thoracic artery and the coeliac artery

Collateralisation around stenotic or occlusive arterial disease is a commonly observed adaptation for maintenance of arterial perfusion. It occurs through pathways of well-understood embryological origin. Examples include Winslow's pathway (internal thoracic artery to iliac artery via the epigastric arteries) and the arc of Riolan (between superior and inferior mesenteric arteries). In this article, we describe a pathway of collateralisation around stenotic disease of the coeliac and superior mesenteric arteries in a 76-year-old man with an abdominal aortic aneurysm. The collateral pathway was identified on computed tomography angiography between the left internal thoracic artery in the thorax and the coeliac artery in the abdomen via the left inferior phrenic artery. This has implications for routine cardiac surgery, such that left internal thoracic artery harvest during coronary artery bypass surgery would likely result in acute ischaemia of the abdominal viscera.

Cardiopulmonary exercise testing and efficacy of percutaneous coronary intervention: a substudy of the ORBITA trial

AIMS

Oxygen-pulse morphology and gas exchange analysis measured during cardiopulmonary exercise testing (CPET) has been associated with myocardial ischaemia. The aim of this analysis was to examine the relationship between CPET parameters, myocardial ischaemia and anginal symptoms in patients with chronic coronary syndrome and to determine the ability of these parameters to predict the placebo-controlled response to percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Patients with severe single-vessel coronary artery disease (CAD) were randomized 1:1 to PCI or placebo in the ORBITA trial. Subjects underwent pre-randomization treadmill CPET, dobutamine stress echocardiography (DSE) and symptom assessment. These assessments were repeated at the end of a 6-week blinded follow-up period.A total of 195 patients with CPET data were randomized (102 PCI, 93 placebo). Patients in whom an oxygen-pulse plateau was observed during CPET had higher (more ischaemic) DSE score [+0.82 segments; 95% confidence interval (CI): 0.40 to 1.25, P = 0.0068] and lower fractional flow reserve (-0.07; 95% CI: -0.12 to -0.02, P = 0.011) compared with those without. At lower (more abnormal) oxygen-pulse slopes, there was a larger improvement of the placebo-controlled effect of PCI on DSE score [oxygen-pulse plateau presence (Pinteraction = 0.026) and oxygen-pulse gradient (Pinteraction = 0.023)] and Seattle angina physical-limitation score [oxygen-pulse plateau presence (Pinteraction = 0.037)]. Impaired peak VO2, VE/VCO2 slope, peak oxygen-pulse, and oxygen uptake efficacy slope was significantly associated with higher symptom burden but did not relate to severity of ischaemia or predict response to PCI.

CONCLUSION

Although selected CPET parameters relate to severity of angina symptoms and quality of life, only an oxygen-pulse plateau detects the severity of myocardial ischaemia and predicts the placebo-controlled efficacy of PCI in patients with single-vessel CAD.

The association of PRECISE-DAPT score with ischaemic outcomes in patients taking dual antiplatelet therapy following percutaneous coronary intervention: a meta-analysis

AIMS

The PRECISE-DAPT (Predicting Bleeding Complication in Patients Undergoing Stent Implantation and Subsequent Dual Antiplatelet Therapy) score identifies patients at high risk of bleeding complications following percutaneous coronary intervention (PCI). International guidelines recommend the PRECISE-DAPT score to identify patients at high risk for bleeding, who may benefit from shortened dual antiplatelet therapy. The association of the PRECISE-DAPT score with ischaemic outcomes remains unclear. We performed a meta-analysis investigating the association between a high PRECISE-DAPT score and ischaemic outcomes.

METHODS AND RESULTS

A comprehensive literature search was conducted on articles published between 11 March 2017 and 5 June 2021. Two reviewers independently screened articles for inclusion using pre-defined criteria. The outcome measures extracted included composite ischaemic events, major bleeding events, and all-cause mortality. A random effects model was applied to obtain combined risk estimates for outcomes. From 12 included studies, there were 39 459 patients with PRECISE-DAPT <25 and 14 761 patients with PRECISE-DAPT ≥25. PRECISE-DAPT score ≥25 was associated with increased risk of composite ischaemic events [odds ratio (OR) 2.16; 95% confidence interval (CI) 1.77-2.65], myocardial infarction (OR 2.06; 95% CI 1.38-3.08), and ischaemic stroke (OR 2.90; 95% CI 1.76-4.78). Patients with a PRECISE-DAPT score ≥25 had increased risk of major bleeding (OR 3.62; 95% CI 2.62-4.99). Patients with a PRECISE-DAPT score ≥25 had higher risk of all-cause mortality (OR 5.83; 95% CI 5.37-6.33).

CONCLUSION

Patients with a PRECISE-DAPT score ≥25 are at increased risk for ischaemic events, bleeding, and all-cause mortality. Prospective evaluation of a PRECISE-DAPT guided approach to antiplatelet therapy is required to demonstrate benefit in this high-risk population.

Atrial-paced, exercise-similar heart rate envelope induces myocardial protection from ischaemic injury

AIMS

The study investigates the role and mechanisms of clinically translatable exercise heart rate (HR) envelope effects, without dyssynchrony, on myocardial ischaemia tolerance compared to standard preconditioning methods. Since the magnitude and duration of exercise HR acceleration are tightly correlated with beneficial cardiac outcomes, it is hypothesized that a paced exercise-similar HR envelope, delivered in a maximally physiologic way that avoids the toxic effects of chamber dyssynchrony, may be more than simply a readout, but rather also a significant trigger of myocardial conditioning and stress resistance.

METHODS AND RESULTS

For 8 days over 2 weeks, sedated mice were atrial-paced once daily via an oesophageal electrode to deliver an exercise-similar HR pattern with preserved atrioventricular and interventricular synchrony. Effects on cardiac calcium handling, protein expression/modification, and tolerance to ischaemia-reperfusion (IR) injury were assessed and compared to those in sham-paced mice and to the effects of exercise and ischaemic preconditioning (IPC). The paced cohort displayed improved myocardial IR injury tolerance vs. sham controls with an effect size similar to that afforded by treadmill exercise or IPC. Hearts from paced mice displayed changes in Ca2+ handling, coupled with changes in phosphorylation of calcium/calmodulin protein kinase II, phospholamban and ryanodine receptor channel, and transcriptional remodelling associated with a cardioprotective paradigm.

CONCLUSIONS

The HR pattern of exercise, delivered by atrial pacing that preserves intracardiac synchrony, induces cardiac conditioning and enhances ischaemic stress resistance. This identifies the HR pattern as a signal for conditioning and suggests the potential to repurpose atrial pacing for cardioprotection.

Fluorescence angiography likely protects against anastomotic leak in colorectal surgery: a systematic review and meta-analysis of randomised controlled trials

Objective

Observational studies have shown that fluorescence angiography (FA) decreases the incidence of anastomotic leak (AL) in colorectal surgery, but high-quality pooled evidence was lacking. Therefore, we aimed at confirming this preliminary finding using a systematic review and meta-analysis of randomised controlled trials (RCTs) in the field.

Methods

MEDLINE, Embase and CENTRAL were searched for RCTs assessing the effect of intra-operative FA versus standard assessment of bowel perfusion on the incidence of AL of colorectal anastomosis. The systematic review complied with the PRISMA 2020 and AMSTAR2 recommendations and was registered in PROSPERO. Pooled relative risk (RR) and pooled risk difference (RD) were obtained using models with random effects. Heterogeneity was assessed using the Q-test and quantified using the I² value. Certainty of evidence was assessed using the GRADE Pro tool.

Results

One hundred and eleven articles were screened, 108 were excluded and three were kept for inclusion. The three included RCTs compared assessment of the perfusion of the bowel during creation of a colorectal anastomosis using FA versus standard practice. In meta-analysis, FA was significantly protective against AL (3 RCTs, 964 patients, RR: 0.67, 95% CI: 0.46 to 0.99, I²: 0%, p = 0.04). The RD of AL was non-significantly decreased by 4 percentage points (95%CI: − 0.08 to 0, I²: 8%, p = 0.06) when using FA. Certainty of evidence was considered as moderate.

Conclusion

The effect of FA on prevention of AL in colorectal surgery exists but is potentially of small magnitude. Considering the potential magnitude of effect of FA, we advise that future RCTs have an adequate sample size, include a cost-benefit analysis of the technique and better define the subpopulation who could benefit from FA.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00464-022-09255-1.

Extracellular histones are a target in myocardial ischaemia-reperfusion injury

AIMS

Acute myocardial infarction causes lethal cardiomyocyte injury during ischaemia and reperfusion (I/R). Histones have been described as important Danger Associated Molecular Proteins (DAMPs) in sepsis. The objective of this study was to establish whether extracellular histone release contributes to myocardial infarction.

METHODS AND RESULTS

Isolated, perfused rat hearts were subject to I/R. Nucleosomes and histone-H4 release was detected early during reperfusion. Sodium-β-O-Methyl cellobioside sulfate (mCBS), a newly developed histone-neutralizing compound, significantly reduced infarct size whilst also reducing the detectable levels of histones. Histones were directly toxic to primary adult rat cardiomyocytes in vitro. This was prevented by mCBS or HIPe, a recently described, histone-H4 neutralizing peptide, but not by an inhibitor of TLR4, a receptor previously reported to be involved in DAMP-mediated cytotoxicity. Furthermore, TLR4-reporter HEK293 cells revealed that cytotoxicity of histone H4 was independent of TLR4 and NF-κB. In an in vivo rat model of I/R, HIPe significantly reduced infarct size.

CONCLUSION

Histones released from the myocardium are cytotoxic to cardiomyocytes, via a TLR4-independent mechanism. The targeting of extracellular histones provides a novel opportunity to limit cardiomyocyte death during I/R injury of the myocardium.

The use of fluorescence angiography to assess bowel viability in the acute setting: an international, multi-centre case series

Introduction

Assessing bowel viability can be challenging during acute surgical procedures, especially regarding mesenteric ischaemia. Intraoperative fluorescence angiography (FA) may be a valuable tool for the surgeon to determine whether bowel resection is necessary and to define the most appropriate resection margins. The aim of this study is to report on FA use in the acute setting and to judge its impact on intraoperative decision making.

Materials and methods

This is a multi-centre, retrospective case series of patients undergoing emergency abdominal surgery between February 2016 and 2021 in three general/colorectal units where intraoperative FA was performed to assess bowel viability. Primary endpoint was change of management after the FA assessment.

Results

A total of 93 patients (50 males, 66.6 ± 19.2 years, ASA score ≥ III in 85%) were identified and studied. Initial surgical approach was laparotomy in 66 (71%) patients and laparoscopy in 27 (29% and seven, 26% conversions). The most common aetiologies were mesenteric ischaemia (n = 42, 45%) and adhesional/herniae-related strangulation (n = 41, 44%). In 50 patients a bowel resection was performed. Overall rates of anastomosis after resection, reoperation and 30-day mortality were 48% (n = 24/50, one leak), 12% and 18%, respectively. FA changed management in 27 (29%) patients. In four patients (4% overall), resection was avoided and in 21 (23%) extra bowel length was preserved (median 50 cm of bowel saved, IQR 28–98) although three patients developed further ischaemia. FA prompted extended resection (median of 20 cm, IQR 10–50 extra bowel) in six (6%) patients.

Conclusion

Intraoperative use of FA impacts surgical decisions regarding bowel resection for intestinal ischaemia, potentially enabling bowel preservation in approximately one out of four patients. Prospective studies are needed to optimize the best use of this technology for this indication and to determine standards for the interpretation of FA images and the potential subsequent need for second-look surgeries.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00464-022-09136-7.

Undiagnosed Chronic Obstructive Pulmonary Disease is Highly Prevalent in Patients Referred for Dobutamine Stress Echocardiography with Shortness of Breath

PURPOSE

Shortness of breath (SOB) is a common symptom referral for dobutamine stress echocardiography (DSE). Patients with SOB and a normal DSE have worse long-term outcome than the general population. This suggests multiple aetiologies are involved. The purpose of this study was to assess the prevalence and clinical significance of undiagnosed COPD amongst patients referred for a DSE with SOB.

METHODS

We prospectively studied 114 patients referred for DSE with SOB without prior evidence of lung disease (mean age 64.9 ± 18.5 years, 60 male). Respiratory function testing using spirometry was performed on all patients on the day of their DSE. The study end-points were cardiac events and total mortality.

RESULTS

Respiratory function testing and DSE was performed in all patients and COPD was highly prevalent (n = 93). Multivariate Cox regression analysis was used to estimate the effect of dyspnoea on non-fatal cardiac events (NFCE) and all-cause mortality. Over a mean follow-up of 4.5 ± 2.6 years, the composite end-point of NFCE and all-cause mortality occurred in 62.7% and 16.7% patients, respectively. COPD (HR 1.27; 95% CI 1.17-1.93), previous myocardial infarction (HR 1.84; 95% CI 1.06-3.2), myocardial ischaemia (HR 2.56; 95% CI 1.48-4.43), peak wall motion score index (HR 4.66; 95% CI 2.26-9.6), and mitral E/E' (HR 1.21; 95% CI 1.1-1.33) were significantly associated with a NFCE. Myocardial ischaemia (HR 4.43; 95% CI 1.24-15.81) was the only independent predictor of all-cause mortality.

CONCLUSION

Undiagnosed COPD is highly prevalent and independently associated with worse outcome amongst patients with SOB referred for DSE. Symptom presentation is therefore an important consideration when interpreting DSE results.

Ischaemic gastritis and perforation

Introduction

Gastric perforation is a common general surgical emergency. Ischaemia of the stomach is uncommon due to its rich vascular supply, and is an uncommon cause of perforation. Minimal literature is available on the topic of ischaemic gastritis, with the few cases available linked to gastric dilation.

Presentation of case

A 52 year old lady presents with a syncopal episode, nausea, vomiting, malaise, and abdominal discomfort. A chest X-ray identified free subdiaphragmatic gas, and her examination revealed a peritonitic abdomen, prompting urgent surgical intervention. She was found to have ischaemic gastritis with multiple perforations along the greater curvature, necessitating a sleeve gastrectomy. Her post-operative course was stormy, requiring significant haemodynamic and respiratory support in the intensive care unit with progressive multi-organ dysfunction. She eventually developed extensive bowel ischaemia, and further management was considered futile. She passed away 13 days post-operatively.

Clinical discussion

The vascular supply of the stomach is rich with collaterals, making ischaemia unlikely. Its occurrence requires either a proximal insult, global ischaemia from pressure, or a systemic coagulopathy. Aside from perforation, it may also present with GI bleeding. Depending on its aetiology, the disease has been managed successfully either conservatively, interventionally, or operatively.

Conclusion

Ischaemic gastritis is uncommon and likely underdiagnosed. Timely recognition of its aetiology early in its course is important, for choosing the appropriate management and to improve patient outcomes. Its management is dependent on the aetiology of the perforation.

•

Ischaemic gastritis is uncommon owing to the rich vasculature of the stomach.

•

It may present as upper GI bleeding resulting in underdiagnosis.

•

Ischaemia requires either a proximal insult, pressure related ischaemia, or coagulopathy.

•

Depending on its aetiology, it may be managed conservatively, angriographically, or operatively.

•

Delayed presentation significantly worsens outcomes.

Negative interaction between nitrates and remote ischemic preconditioning in patients undergoing cardiac surgery: the ERIC-GTN and ERICCA studies

Remote ischaemic preconditioning (RIPC) using transient limb ischaemia failed to improve clinical outcomes following cardiac surgery and the reasons for this remain unclear. In the ERIC-GTN study, we evaluated whether concomitant nitrate therapy abrogated RIPC cardioprotection. We also undertook a post-hoc analysis of the ERICCA study, to investigate a potential negative interaction between RIPC and nitrates on clinical outcomes following cardiac surgery. In ERIC-GTN, 185 patients undergoing cardiac surgery were randomized to: (1) Control (no RIPC or nitrates); (2) RIPC alone; (3); Nitrates alone; and (4) RIPC + Nitrates. An intravenous infusion of nitrates (glyceryl trinitrate 1 mg/mL solution) was commenced on arrival at the operating theatre at a rate of 2-5 mL/h to maintain a mean arterial pressure between 60 and 70 mmHg and was stopped when the patient was taken off cardiopulmonary bypass. The primary endpoint was peri-operative myocardial injury (PMI) quantified by a 48-h area-under-the-curve high-sensitivity Troponin-T (48 h-AUC-hs-cTnT). In ERICCA, we analysed data for 1502 patients undergoing cardiac surgery to investigate for a potential negative interaction between RIPC and nitrates on clinical outcomes at 12-months. In ERIC-GTN, RIPC alone reduced 48 h-AUC-hs-cTnT by 37.1%, when compared to control (ratio of AUC 0.629 [95% CI 0.413-0.957], p = 0.031), and this cardioprotective effect was abrogated in the presence of nitrates. Treatment with nitrates alone did not reduce 48 h-AUC-hs-cTnT, when compared to control. In ERICCA there was a negative interaction between nitrate use and RIPC for all-cause and cardiovascular mortality at 12-months, and for risk of peri-operative myocardial infarction. RIPC alone reduced the risk of peri-operative myocardial infarction, compared to control, but no significant effect of RIPC was demonstrated for the other outcomes. When RIPC and nitrates were used together they had an adverse impact in patients undergoing cardiac surgery with the presence of nitrates abrogating RIPC-induced cardioprotection and increasing the risk of mortality at 12-months post-cardiac surgery in patients receiving RIPC.

Long-term prognostic value of vasodilator stress cardiac magnetic resonance in patients with atrial fibrillation

AIMS

Although the prevalence of coronary artery disease (CAD) is high among patients with atrial fibrillation (AF), studies on stress perfusion cardiac magnetic resonance (CMR) imaging frequently exclude patients with AF, and its prognostic and diagnostic value in high-risk patients with suspected or known CAD remains unclear.

METHODS AND RESULTS

In this longitudinal cohort study, we included 164 consecutive patients with AF during vasodilator perfusion CMR. Diagnostic value was evaluated regarding invasive coronary angiography in a subset of patients. We targeted a follow-up of >5 years and used CMR results as stratification, and the primary outcome was major adverse cardiac events [MACE, cardiovascular (CV) death and myocardial infarction (MI)]. Secondary outcomes included late coronary revascularization or stroke and the components of the primary outcome. Of the whole cohort (73.8% male, mean age 72.2 years ± 7.8 SD), 99.4% were successfully scanned (163/164 patients). Median CHA2DS2-VASc score was 4 [interquartile range (IQR) 3-5], and median 10-year risk for CV events based on SMART risk score was high (24%, IQR 16-32%). Thirty-two patients (19.6%) presented with ischaemia and 52 patients (31.9%) with late gadolinium enhancement (LGE). A combination of LGE and inducible ischaemia was present in 20 patients (12.3%). Diagnostic accuracy was 86.2% [confidence interval (CI) 68.3-96.1%]. The median follow-up was 6.6 years (IQR 3.6-7.8). Ischaemia in vasodilator perfusion CMR was significantly associated with the occurrence of MACE [P < 0.01; hazard ratio (HR) 2.65, CI 1.39-5.08], as well as LGE (P = 0.03; 1.74, CI 1.07-3.64) and the combination of both (P < 0.01; HR 2.67, CI 1.59-5.62). After adjustment by age, left ventricular ejection fraction, and the presence of diabetes, ischaemia in vasodilator perfusion CMR remained significantly associated with the occurrence of MACE (2.10, CI 1.08-4.10; P = 0.03). In secondary endpoint analysis, there was a significant association of ischaemia in CMR with CV death (P < 0.05; HR 1.93, CI 0.95-3.9) and MI (P < 0.01; HR 13, CI 1.35-125.4), while no significant association was found regarding the occurrence of revascularization (P = 0.45; HR 1.43, CI 0.57-3.58) or stroke (P = 0.99; HR 0.99, CI 0.21-2.59).

CONCLUSIONS

Vasodilator stress perfusion CMR demonstrated an excellent diagnostic and significant prognostic value at long-term follow-up in high-risk patients with persistent AF and suspected or known CAD.

Prognostic value of pre-hospitalization stress perfusion cardiovascular magnetic resonance to predict death in patients hospitalized for COVID-19

Background

Inducible ischaemia is a strong marker of vascular vulnerability. Knowing the important role of the vascular tropism of COVID-19 to explain its severity, the presence of a prior inducible ischaemia may be a key pathogenetic determinant of COVID-19 severity.

Aims

To investigate the prognostic value of prior inducible ischaemia on stress cardiovascular magnetic resonance (CMR) to predict death in patients hospitalized for COVID-19.

Methods

We retrospectively analysed consecutive patients referred for stress perfusion CMR during 1/1/18–1/1/20 who were later hospitalized for COVID-19. The primary outcome was all-cause death, including in-hospital and post-hospitalization deaths, based on the electronic national death registry.

Results

Among the patients referred for stress CMR, 481 were hospitalized for COVID-19 (mean age 68.4 ± 9.6 years, 61.3% male) and completed the follow-up (median [interquartile range] 73 [36–101] days). There were 93 (19.3%) all-cause deaths, of which 13.7% occurred in hospital and 5.6% were post-hospitalization deaths. Age, male sex, hypertension, diabetes, known coronary artery disease (CAD), the presence of prior inducible ischaemia, the number of ischaemic segments, the presence of late gadolinium enhancement and left ventricular ejection fraction were significantly associated with all-cause death. In multivariable stepwise Cox regression analysis, age (hazard ratio [HR]: 1.04, 95% confidence interval [CI]: 1.01–1.07; P = 0.023), hypertension (HR: 2.77; 95% CI: 1.71–4.51; P < 0.001), diabetes (HR: 1.72; 95% CI: 1.08–2.74; P = 0.022), known CAD (HR: 1.78; 95% CI: 1.07–2.94; P = 0.025) and prior inducible ischaemia (HR 2.05; 95% CI: 1.27–3.33; P = 0.004) were independent predictors of all-cause death.

Conclusions

In COVID-19 patients, prior inducible ischaemia by stress CMR during the 2 years preceding the COVID-19 pandemic was independently associated with all-cause death.

The ISCHEMIA trial: optimal medical therapy against PTCA in the stable patient: the endless story

In patients with acute coronary syndrome, an aggressive approach with coronary angiography and revascularization leads to important benefits compared to medical therapy alone. On the contrary, the prognostic impact of coronary revascularization in patients suffering from stable coronary artery disease has long been the subject of debate. The pivotal study in this area is COURAGE, published in 2007, in which coronary revascularization showed no benefit about the combined endpoint of death from all causes and acute myocardial infarction (AMI), compared to medical therapy. The ISCHEMIA study, published in 2020, compared selective coronary angiography and revascularization vs. a non-invasive approach. By protocol, the patients were initially evaluated with coronary computed axial tomography angiography: in case of coronary stenosis >50%, they were then randomized to the two strategies. While in the invasive arm patients were revascularized, in the non-invasive arm revascularization was used only in case of patient destabilization. As in COURAGE, the results of ISCHEMIA did not demonstrate superiority of revascularization over medical therapy alone for a combined endpoint of cardiovascular death, AMI, or hospitalization for unstable angina, heart failure, or cardiac arrest. Based on recent evidence from ISCHEMIA, it is therefore confirmed that coronary revascularization in stable patients does not seem to improve the prognosis compared to medical therapy alone.

β-hydroxybutyrate accumulates in the rat heart during low-flow ischaemia with implications for functional recovery

Extrahepatic tissues which oxidise ketone bodies also have the capacity to accumulate them under particular conditions. We hypothesised that acetyl-coenzyme A (acetyl-CoA) accumulation and altered redox status during low-flow ischaemia would support ketone body production in the heart. Combining a Langendorff heart model of low-flow ischaemia/reperfusion with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS), we show that β-hydroxybutyrate (β-OHB) accumulated in the ischaemic heart to 23.9 nmol/gww and was secreted into the coronary effluent. Sodium oxamate, a lactate dehydrogenase (LDH) inhibitor, increased ischaemic β-OHB levels 5.3-fold and slowed contractile recovery. Inhibition of β-hydroxy-β-methylglutaryl (HMG)-CoA synthase (HMGCS2) with hymeglusin lowered ischaemic β-OHB accumulation by 40%, despite increased flux through succinyl-CoA-3-oxaloacid CoA transferase (SCOT), resulting in greater contractile recovery. Hymeglusin also protected cardiac mitochondrial respiratory capacity during ischaemia/reperfusion. In conclusion, net ketone generation occurs in the heart under conditions of low-flow ischaemia. The process is driven by flux through both HMGCS2 and SCOT, and impacts on cardiac functional recovery from ischaemia/reperfusion.

The emerging role of mechanical and topographical factors in the development and treatment of nervous system disorders: dark and light sides of the force

Nervous system diseases are the subject of intensive research due to their association with high mortality rates and their potential to cause irreversible disability. Most studies focus on targeting the biological factors related to disease pathogenesis, e.g. use of recombinant activator of plasminogen in the treatment of stroke. Nevertheless, multiple diseases such as Parkinson’s disease and Alzheimer’s disease still lack successful treatment. Recently, evidence has indicated that physical factors such as the mechanical properties of cells and tissue and topography play a crucial role in homeostasis as well as disease progression. This review aims to depict these factors’ roles in the progression of nervous system diseases and consequently discusses the possibility of new therapeutic approaches. The literature is reviewed to provide a deeper understanding of the roles played by physical factors in nervous system disease development to aid in the design of promising new treatment approaches.

(H)IF applicable: promotion of neurogenesis by induced HIF-2 signalling after ischaemia

HIF-2 represents a tissue-specific isoform of the hypoxia-inducible factors (HIFs) which regulate oxygen homeostasis in the cell. In acute oxygen deficiency, HIF transcription factors ensure the timely restoration of adequate oxygen supply. Particularly in medical conditions such as stroke, which have a high mortality risk due to ischaemic brain damage, rapid recovery of oxygen supply is of extraordinary importance. Nevertheless, the endogenous mechanisms are often not sufficient to respond to severe hypoxic stress with restoring oxygenation and fail to protect the tissue. Herein, we analysed murine neurospheres without functioning HIF-2α and found that special importance in the differentiation of neurons can be attributed to HIF-2 in the brain. Other processes, such as cell migration and signal transduction of different signalling pathways, appear to be mediated to some extent via HIF-2 and illustrate the function of HIF-2 in brain remodelling. Without hypoxic stress, HIF-2 in the brain presumably focuses on the fine-tuning of the neural network. However, a therapeutically increase of HIF-2 has the potential to regenerate or replace destroyed brain tissue and help minimize the consequences of an ischaemic stroke.

Early invasive coronary angiography and acute ischaemic heart failure outcomes

Aims 

While myocardial ischaemia plays a major role in the pathogenesis of heart failure (HF), the indications for coronary angiography during acute HF are not established. We determined the association of early coronary angiography during acute HF hospitalization with 2-year mortality, cardiovascular death, HF readmissions, and coronary revascularization.

Methods and results 

In a two-stage sampling process, we identified acute HF patients who presented to 70 emergency departments in Ontario (April 2010 to March 2013) and determined whether they underwent early coronary angiography within 14 days after presentation using administrative databases. After clinical record review, we defined a cohort with acute ischaemic HF as patients with at least one factor suggesting underlying ischaemic heart disease, including previous myocardial infarction, troponin elevation, or angina on presentation. We oversampled patients undergoing angiography. We used inverse-probability-of-treatment weighting (IPTW) to adjust for baseline differences. Of 7239 patients with acute HF, 2994 met inclusion criteria [median age 75 (interquartile range 65–83) years; 40.9% women]. Early angiography was performed in 1567 patients (52.3%) and was associated with lower all-cause mortality [hazard ratio (HR) 0.74, 95% confidence interval (CI) 0.61–0.90, P = 0.002], cardiovascular death (HR 0.72, 95% CI 0.56–0.93, P = 0.012), and HF readmissions (HR 0.84, 95% CI 0.71–0.99, P = 0.042) after IPTW. Those undergoing early angiography experienced higher rates of percutaneous coronary intervention (HR 2.58, 95% CI 1.73–3.86, P < 0.001) and coronary artery bypass grafting (HR 2.94, 95% CI 1.75–4.93, P < 0.001) within 2 years.

Conclusions 

Early coronary angiography was associated with lower all-cause mortality, cardiovascular death, HF readmissions, and higher rates of coronary revascularization in acute HF patients with possible ischaemia.

Vasodilatation stress cardiovascular magnetic resonance imaging: Feasibility, workflow and safety in a large prospective registry of more than 35,000 patients

BACKGROUND

Cardiovascular magnetic resonance imaging (CMR) is an accurate technique for assessing ventricular function, myocardial perfusion and viability; its development remains limited mainly because of logistical and time constraints. Data regarding optimization of a dedicated stress CMR workflow are needed.

AIMS

This study aimed to describe the optimization of a dedicated workflow, and to assess the feasibility and safety of stress CMR in a large registry of>35,000 patients.

METHODS

A large single-centre French registry of vasodilator stress CMR included consecutive patients referred between 2008 and 2019 for the detection of inducible ischaemia. Stress CMR was performed at 1.5 Tesla using dipyridamole. Clinical and demographic data, test quality, CMR findings, haemodynamic data and complications were recorded prospectively. A locally optimized workflow was described and evaluated.

RESULTS

Among the 35,862 patients referred for vasodilator stress CMR (mean age 68.9±11.8 years; 64.1% male), the stress CMR protocol was completed in 35,013 (97.6%) patients; 144 (0.3%) patients with missing baseline data were excluded. The mean examination duration was 27±5min, with image quality optimal in 90.8%, suboptimal in 7.1% and poor in 0.5% of cases. Images were diagnostic in 97.9% of patients. No patients died during or immediately after CMR. Fifty-six (0.16%) patients had severe complications. The incidence of non-severe complications was low (1.5%), whereas minor symptoms occurred frequently (35.5%). The presence of ischaemia was associated with a higher incidence of severe complications, non-severe complications and minor symptoms (all P<0.001).

CONCLUSIONS

This single-centre prospective registry of>35,000 referral patients with known or suspected CAD showed that stress CMR was feasible in clinical routine practice, with high diagnostic image quality and an excellent safety profile. Inducible ischaemia was associated with severe complications, non-severe complications and minor symptoms.

Hypoxia and chronic kidney disease: Possible mechanisms, therapeutic targets, and relevance to cats

There is mounting evidence that kidney ischaemia/hypoxia plays an important role in feline chronic kidney disease (CKD) development and progression, as well as in human disease and laboratory animal models. Ischaemic acute kidney injury is widely accepted as a cause of CKD in people and data from laboratory species has identified some of the pathways underlying this continuum. Experimental kidney ischaemia in cats results in morphological changes, namely chronic tubulointerstitial inflammation, tubulointerstitial fibrosis, and tubular atrophy, akin to those observed in naturally-occurring CKD. Multiple situations are envisaged that could result in acute or chronic episodes of kidney hypoxia in cats, while risk factors identified in epidemiological studies provide further support that kidney hypoxia contributes to spontaneously occurring feline CKD. This review evaluates the evidence for the role of kidney ischaemia/hypoxia in feline CKD and the proposed mechanisms and consequences of kidney hypoxia. As no effective treatments exist that substantially slow or prevent feline CKD progression, there is a need for novel therapeutic strategies. Targeting kidney hypoxia is one such promising approach, with therapies including those that attenuate the hypoxia-inducible factor (HIF) pathway already being utilised in human CKD.

Prognostic value of stress cardiovascular magnetic resonance in asymptomatic patients without known coronary artery disease

OBJECTIVES

A few studies suggest a significant prognostic value of silent myocardial ischaemia detected in asymptomatic patients. However, the current guidelines do not recommend stress testing in asymptomatic individuals. To assess the long-term prognostic value of vasodilator stress perfusion cardiovascular magnetic resonance (CMR) in asymptomatic individuals without known coronary artery disease (CAD).

METHODS

Between 2009 and 2011, a retrospective cohort study with a median follow-up of 9.2 years (interquartile range: 7.8-9.6) included 1,027 consecutive asymptomatic individuals with ≥ 2 cardiovascular risk factors but without known known CAD referred for stress CMR. Major adverse cardiovascular events (MACE) included cardiovascular mortality and nonfatal myocardial infarction (MI).

RESULTS

Among 1,027 asymptomatic subjects, 903 (87.9%) (mean age 70.6 ± 12.4 years and 46.2% males) completed the follow-up, and 91 had MACE (10.1%). Using Kaplan-Meier analysis, silent ischaemia and unrecognised MI were associated with MACE (hazard ratio [HR]: 8.70; 95% CI: 5.79-13.10 and HR: 3.40; 95% CI: 2.15-5.38, respectively; both p < 0.001). In multivariable stepwise Cox regression, silent ischaemia and unrecognised MI were independent predictors of MACE (HR: 6.66; 95% CI 4.41-9.23; and HR: 2.42; 95% CI 1.23-3.21, respectively; both p < 0.001). The addition of silent ischaemia and unrecognised MI led to improved model discrimination for MACE (change in C statistic from 0.66 to 0.82; NRI = 0.497; IDI = 0.070).

CONCLUSIONS

Silent ischaemia and unrecognised MI are good long-term predictors for the incidence of MACE in selected asymptomatic individuals with multiple risk factors and without known CAD. These stress CMR parameters have incremental long-term prognostic value to predict MACE over traditional risk factors.

KEY POINTS

• Silent ischaemia and unrecognised myocardial infarction defined by stress CMR are good long-term predictors of cardiovascular events in asymptomatic individuals without known coronary artery disease. • The addition of stress cardiac MR imaging led to improved model discrimination for cardiovascular events over traditional risk factors in this specific population.

Real time measurement of intramuscular pH during routine knee arthroscopy using a tourniquet : a preliminary study

AIMS

Tourniquets have potential adverse effects including postoperative thigh pain, likely caused by their ischaemic and possible compressive effects. The aims of this preliminary study were to determine if it is possible to directly measure intramuscular pH in human subjects over time, and to measure the intramuscular pH changes resulting from tourniquet ischaemia in patients undergoing knee arthroscopy.

METHODS

For patients undergoing short knee arthroscopic procedures, a sterile calibrated pH probe was inserted into the anterior fascial compartment of the leg after skin preparation, but before tourniquet inflation. The limb was elevated for three minutes prior to tourniquet inflation to 250 mmHg or 300 mmHg. Intramuscular pH was recorded at one-second intervals throughout the procedure and for 20 minutes following tourniquet deflation. Probe-related adverse events were recorded.

RESULTS

A total of 27 patients were recruited to the study. Mean tourniquet time was 21 minutes (10 to 56). Tourniquet pressure was 300 mmHg for 21 patients and 250 mmHg for six patients. Mean muscle pH prior to tourniquet inflation was 6.80. Muscle pH decreased upon tourniquet inflation, with a steeper fall in the first ten minutes than for the rest of the procedure. Change in muscle pH was significant after five minutes of tourniquet ischaemia (p < 0.001). Mean muscle pH prior to tourniquet release was 6.58 and recovered to 6.75 within 20 minutes following release. No probe related adverse events were recorded.

CONCLUSION

It is possible to directly measure skeletal muscle pH in human subjects over time. Tourniquet ischaemia results in a decrease in human skeletal muscle pH over time during short procedures. Cite this article: Bone Joint Res 2021;10(6):363-369.

Ischaemic monomelic neuropathy: A rare cause of unilateral foot drop

Ischaemic neuropathy is a rare phenomenon given the rich arterial collateral supply afforded to peripheral nerves by the vasa nervorum. We report an unusual case of unilateral foot drop secondary to long-segment popliteal artery occlusion. Without expedient vessel imaging and revascularisation of the occluded artery, this reversible cause of neurological deficit would likely have resulted in a poor functional outcome for our patient.

Histological, behavioural and flow cytometric datasets relating to acute ischaemic stroke in young, aged and ApoE-/- mice in the presence and absence of immunomodulation with fingolimod

In this work, the sphingosine-1-phosphate receptor modulator fingolimod was assessed as a preclinical candidate for the treatment of acute ischaemic stroke according to the Stroke Therapy Academic Industry Roundtable (STAIR) preclinical recommendations. Young (15-17 weeks), aged (72-73 weeks), and ApoE^-/- mice (20-21 weeks) fed a high fat diet (all C57BL/6 mice) underwent permanent electrocoagulation of the left middle cerebral artery. Mice received either saline or fingolimod (0.5 mg/kg or 1 mg/kg) at 2-, 24-, and 48-hours post-ischaemia via intraperitoneal (i.p.) injection. Another cohort of young mice (8-9 and 17-19 weeks) received short-term (5 days) or long-term (10 days) fingolimod (0.5 mg/kg) treatment in a treatment duration study. For young, aged, and ApoE^-/- mice, motor behavioural tests (cylinder and grid-walking) were performed at days 0, 3, and 7 post-ischaemia to evaluate neurobehavioural recovery. In the treatment duration study, the grid-walking test was performed at days 0, 2, 5 and 10 post-ischaemia. Brain tissue sections were stained with haematoxylin and eosin (H&E), and NeuN to quantify tissue damage. Flow cytometry was used to quantify T cell populations in blood, spleen, and lymph nodes. The data presented in this article improves our understanding of the potential neuroprotective and immunomodulatory effects of fingolimod in a mouse model of brain ischaemia. Such data may be significant in the design of future preclinical and clinical stroke studies for fingolimod.