RESPIRATORY GAS EXCHANGE INDICES FOR ESTIMATING THE ANAEROBIC THRESHOLD

Several methods are used for estimating the anaerobic threshold (AT) during exercise. The aim of the present study was to compare AT values based on blood lactate measurements with those obtained from computerised calculations of different respiratory gas indices. Twelve healthy, well-trained men performed a stepwise incremental test on both treadmill and cycle ergometer. Respiratory gases were measured continuously, and blood samples were drawn every third minute. AT was determined, based on 1) blood lactate concentrations (Lactate-AT), 2) respiratory exchange ratio (RER-AT), 3) V- slope method (Vslope-AT), and 4) ventilatory equivalent for VO2 (EqO2-AT). Lactate-AT and RER-AT values showed similar values, both on treadmill and on cycle ergometer. EqO2-AT showed a trend towards lower values for AT, while Vslope-AT gave significantly lower values for AT for both exercise modes. Bland-Altman plots showed an even distribution of data for RER-AT, while a more scattered and skewed distribution of data was observed when EqO2-AT and Vslope-AT were compared with Lactate-AT. The study demonstrates that RER-based estimates of AT correlate well with the blood lactate-based AT determination. The RER method is non-invasive and simple to perform, and, in the present study, seemed to be the best respiratory index for estimation of AT

Microvascular function and inflammatory activation in Takotsubo cardiomyopathy

Abstract Aims The aim of this study was to determine microvascular function in the acute phase of Takotsubo syndrome (TTS) and to identify inflammatory mediators that could reflect TTS‐induced pathology. Methods and results The study included 20 females [median age 65 years; interquarile range (IQR) = 58–70 years] with TTS according to the Mayo diagnostic criteria. During heart catheterization, we determined the index of microvascular resistance (IMR) and drew blood samples almost simultaneously from the aorta and coronary sinus. Cardiac magnetic resonance imaging (MRI) was done in the acute phase. We present descriptive coronary physiology and cardiac MRI data and compare inflammatory biomarkers between samples from the aorta, coronary sinus, and venous samples after 3 months using the Wilcoxon signed‐rank test. For comparison, we also analysed the actual biomarkers in venous blood from 15 healthy female controls. A supplementary analysis explored Spearman's rank correlation between the inflammatory biomarkers, IMR, MRI data, and cardiac biomarkers. The median IMR was 16.5 mmHg·s (IQR = 10.5–28.2 mmHg·s), which was only slightly higher than that in the reference populations. Seven (35%) of the study subjects had IMR > 25 mmHg·s, suggesting a microvascular dysfunction. IMR was not affected by time from symptom onset. According to MRI, the apical region of the left ventricle was affected in 65% of the subjects. The median ejection fraction was 41% (IQR = 31–48%). Biomarker analyses revealed elevation of markers for extracellular matrix remodelling and fibrosis, inflammation, immune activation, and upstream inflammation as compared with healthy controls. Only the levels of interleukin (IL)‐1 receptor antagonist and soluble T‐cell immunoglobulin mucin domain‐3 (sTIM‐3) were higher in the coronary sinus than in the aorta. No variable was significantly correlated with IMR. The IL‐6 level in the aorta was inversely correlated with the left ventricular ejection fraction. Growth differentiation factor‐15, osteoprotegerin, and von Willebrand factor levels in both aorta and coronary sinus were positively correlated with N‐terminal‐pro‐brain‐natriuretic peptide, while the correlations of IL‐6 and sTIM‐3 with N‐terminal‐pro‐brain‐natriuretic peptide were restricted to the aorta and coronary sinus, respectively. While most of the markers were within normal limits after 3 months, matrix metalloproteinase‐9 increased during follow‐up to reach levels higher than those in the healthy controls. Conclusion The median IMR was only slightly elevated in this study, but about one‐third of the patients had values indicating microvascular dysfunction. The present study supports the involvement of several inflammatory pathways in TTS, including monocyte/macrophage activation, with sTIM‐3 as a potential novel marker

Laboratory test of Single Landmark registration method for ultrasound-based navigation in laparoscopy using an open-source platform

Purpose Test the feasibility of the novel Single Landmark image-to-patient registration method for use in the operating room for future clinical trials. The algorithm is implemented in the open-source platform CustusX, a computer-aided intervention research platform dedicated to intraoperative navigation and ultrasound, with an interface for laparoscopic ultrasound probes. Methods The Single Landmark method is compared to fiducial landmark on an IOUSFAN (Kyoto Kagaku Co., Ltd., Japan) soft tissue abdominal phantom and T2 magnetic resonance scans of it. Results The experiments show that the accuracy of the Single Landmark registration is good close to the registered point, increasing with the distance from this point (12.4 mm error at 60 mm away from the registered point). In this point, the registration accuracy is mainly dominated by the accuracy of the user when clicking on the ultrasound image. In the presented set-up, the time required to perform the Single Landmark registration is 40% less than for the FLRM. Conclusion The Single Landmark registration is suitable for being integrated in a laparoscopic workflow. The statistical analysis shows robustness against translational displacements of the patient and improvements in terms of time. The proposed method allows the clinician to accurately register lesions intraoperatively by clicking on these in the ultrasound image provided by the ultrasound transducer. The Single Landmark registration method can be further combined with other more accurate registration approaches improving the registration at relevant points defined by the clinicians

Laboratory test of Single Landmark registration method for ultrasound-based navigation in laparoscopy using an open-source platform

Purpose Test the feasibility of the novel Single Landmark image-to-patient registration method for use in the operating room for future clinical trials. The algorithm is implemented in the open-source platform CustusX, a computer-aided intervention research platform dedicated to intraoperative navigation and ultrasound, with an interface for laparoscopic ultrasound probes. Methods The Single Landmark method is compared to fiducial landmark on an IOUSFAN (Kyoto Kagaku Co., Ltd., Japan) soft tissue abdominal phantom and T2 magnetic resonance scans of it. Results The experiments show that the accuracy of the Single Landmark registration is good close to the registered point, increasing with the distance from this point (12.4 mm error at 60 mm away from the registered point). In this point, the registration accuracy is mainly dominated by the accuracy of the user when clicking on the ultrasound image. In the presented set-up, the time required to perform the Single Landmark registration is 40% less than for the FLRM. Conclusion The Single Landmark registration is suitable for being integrated in a laparoscopic workflow. The statistical analysis shows robustness against translational displacements of the patient and improvements in terms of time. The proposed method allows the clinician to accurately register lesions intraoperatively by clicking on these in the ultrasound image provided by the ultrasound transducer. The Single Landmark registration method can be further combined with other more accurate registration approaches improving the registration at relevant points defined by the clinicians.publishedVersion© The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/

Using the CustusX toolkit to create an image guided bronchoscopy application: Fraxinus

Purpose The aim of this paper is to show how a specialized planning and guidance application called Fraxinus, can be built on top of the CustusX platform (www.custusx.org), which is an open source image-guided intervention software platform. Fraxinus has been customized to meet the clinical needs in navigated bronchoscopy. Methods The application requirements for Fraxinus were defined in close collaboration between research scientists, software developers and clinicians (pulmonologists), and built on top of CustusX. Its superbuild system downloads specific versions of the required libraries and builds them for the application in question, including the selected plugins. New functionality is easily added through the plugin framework. The build process enables the creation of specialized applications, adding additional documentation and custom configurations. The toolkit’s libraries offer building blocks for image-guided applications. An iterative development process was applied, where the clinicians would test and provide feedback during the entire process. Results Fraxinus has been developed and is released as an open source planning and guidance application built on top of CustusX. It is highly specialized for bronchoscopy. The proposed workflow is adapted to the different steps in this procedure. The user interface of CustusX has been modified to enhance information, quality assurance and user friendliness with the intention to increase the overall yield for the patient. As the workflow of the procedure is relatively constant, some actions are predicted and automatically performed by the application, according to the requirements from the clinicians. Conclusions The CustusX platform facilitates development of new and specialized applications. The toolkit supports the process and makes important extension and injection points available for customization.publishedVersio

3D ultrasound reconstruction algorithms from analog and digital data

acceptedVersio

Index of microvascular resistance to assess the effect of rosuvastatin on microvascular function in women with chest pain and no obstructive coronary artery disease: A double-blind randomized study

Introduction - Many women undergoing coronary angiography for chest pain have no or only minimal coronary artery disease (CAD). However, despite the lack of obstructive CAD, they still have an increased risk of major adverse cardiovascular events. Pleiotropic effects of statins may influence microvascular function, but if statins improve microvascular function in unselected chest pain patients is not well studied. This study assessed microvascular function by using the thermodilution‐derived test “the index of microvascular resistance” (IMR) with the aim of determining the (i) IMR level in women with chest pain and non‐obstructive CAD and if (ii) IMR is modified by high‐dose statin treatment in these patients. Additional objectives were to identify the influence of statins on the health status as assessed with generic health questionnaires and on biomarkers of endothelial activation. Materials and methods - The study was a randomized, double‐blind, single‐center trial comparing 6 months of rosuvastatin treatment with placebo. In total, 66 women without obstructive CAD were included. Mean age was 52.7 years and 55.5 years in the placebo and rosuvastatin group, respectively. Microvascular function was assessed using the IMR, health status was assessed using the SF‐36 and EQ‐5D questionnaires, and biochemical values were assessed at baseline and 6 months later. Results and conclusions - In the placebo group IMR was 14.6 (SD 5.7) at baseline and 14.4 (SD 6.5) at follow‐up. In the rosuvastatin group IMR was 16.5 (SD 7.5) at baseline and 14.2 (SD 5.8) at follow‐up. IMR did not differ significantly between the two study groups at follow‐up controlled for preintervention values. C‐reactive protein (CRP) was comparable between the groups at baseline, while at follow‐up CRP was significantly lower in the rosuvastatin group compared to placebo [0.6 (±0.5) mg/L vs. 2.6 (±3.0) mg/L; p = 0.002]. Whereas rosuvastatin treatment for 6 months attenuated CRP levels, it did not improve microvascular function as assessed by IMR (Clinical Trials.gov NCT 01582165, EUDRACT 2011‐002630‐39.3tcAZ)

A randomized clinical study using optical coherence tomography to evaluate the short-term effects of high-intensity interval training on cardiac allograft vasculopathy: a HITTS substudy

Cardiac allograft vasculopathy (CAV) remains a leading cause of long-term mortality after heart transplantation. Both preventive measures and treatment options are limited. This study aimed to evaluate the short-term effects of high-intensity interval training (HIT) on CAV in de novo heart transplant (HTx) recipients as assessed by optical coherence tomography (OCT). The study population was a subgroup of the 81-patient HITTS study in which HTx recipients were randomized to HIT or moderate intensity continuous training (MICT) for nine consecutive months. OCT images from baseline and 12 months were compared to assess CAV progression. The primary endpoint was defined as the change in the mean intima area. Paired OCT data were available for 56 patients (n = 23 in the HIT group and n = 33 in the MICT group). The intima area in the entire study population increased by 25% [from 1.8±1.4 mm2 to 2.3±2.0 mm2, P < .05]. The change was twofold higher in the MICT group (.6±1.2 mm2) than in the HIT group (.3±.6 mm2). However, the treatment effect of HIT was not significant (treatment effect = –.3 mm2, 95% CI [–.825 to .2 mm2] P = .29). These results suggest that early initiation of HIT compared with MICT does not attenuate CAV progression in de novo HTx recipients