Impact of decentralized management on sickness absence in hospitals: a two-wave cohort study of frontline managers in Danish hospital wards.

BACKGROUND: This study explores the impact of decentralized management on the sickness absence among healthcare professionals. Sickness absence is a reliable indicator of employees' wellbeing and it is linked to management quality. However, the influence of decentralized management on sickness absence has not been adequately studied. METHODS: The research design combined a two-wave, web-survey of frontline managers in two Danish university hospitals with administrative data on sickness absence at the ward-level. The first and second wave included data from 163165 and 137 frontline managers linked to 121 wards and 108 wards. Data was analysed using an ordinal logistic regression model. RESULTS: Wards where frontline managers had the highest level of decentralised decision authority compared to none showed lower odds of ward-level sickness absence (ORcrude: 0.20, 95% CI: 0.05-0.87). A very high extent of cross-functional decision authority showed lower odds of sickness absence (ORcrude: 0.08, 95% CI: 0.01-0.49). Overall, the results showed a clear data trend, although not all results were statistically significant. CONCLUSION: Higher levels of decentralized management in wards were positively associated with lower risks of sickness absence in hospital wards. The study supports future research on how to empower decision autonomy at the frontline level of management.

The role of non-invasive imaging techniques in detecting intra-abdominal adhesions: a systematic review.

BACKGROUND: Intra-abdominal adhesions after surgery are highly prevalent. Adhesions implicate complications during subsequent surgery and can cause chronic abdominal pain. The objective of this review was to investigate the usefulness of non-invasive diagnostic methods for detection of adhesions. METHODS: We searched the electronic databases: MEDLINE, Embase, and The Cochrane Central Register of Controlled Trials for studies investigating the use of non-invasive diagnostic imaging techniques for detecting adhesions. Main outcome was the sensitivity and specificity of each technique. We used the Quality Assessment of Diagnostic Accuracy studies tool to assess bias. RESULTS: In total, 25 studies were included: 18 using ultrasound (US), 5 using magnetic resonance imaging (MRI), 1 using computed tomography (CT), and 1 using both US and MRI. A total of 2195 patients were included. Overall accuracy ranged between 76 and 100% for US studies and between 79 and 90% for MRI and was 66% for CT. Sensitivity ranged between 21 and 100% for US and between 22 and 93% for MRI and was 61% for CT. Specificity was 32-100% for US, 25-93% for MRI, and 63% for CT. Bias analysis revealed that in most studies, investigators were blinded to the reference standard but not to the index test and 11 of 25 studies had a high risk of selection bias. CONCLUSIONS: Currently, abdominal US can be used to determine the presence of adhesions between bowel and the abdominal wall. MRI is also an accurate diagnostic modality and can in addition visualize adhesions between viscera, however, with a tendency to over diagnose adhesions. There is insufficient evidence to support CT as a diagnostic modality for adhesions.

In-Vivo Evaluation of Flexible Mitral Annuloplasty Rings: Are They All the Same?

BACKGROUND: Currently, several different flexible mitral annuloplasty rings are available, and their efficacy for surgical repair of the mitral valve is, in general, considered equal. However, clinical experience indicates differences in remodeling capacity that have not yet been quantitatively assessed. The study aim was to compare the biomechanical properties of two commonly used flexible mitral annuloplasty rings in an acute pig model. METHODS: Medtronic Simulus Flex (n = 5) and Medtronic Duran AnCore (n = 7) flexible mitral annuloplasty rings were implanted in pigs (bodyweight 80 kg). The native mitral valve was used as a reference (n = 7). Mitral annular dynamics and dimensions were assessed using 11 sonomicrometry crystals placed in the mitral apparatus. A dedicated force transducer was used to detect deformational force transmission between the annuloplasty ring and the mitral annulus. RESULTS: Cyclic changes in mitral annular circumference and commissure-commissure distance were significantly reduced in the Simulus Flex group compared to the Duran AnCore group (p = 0.025 and p <0.01, respectively). In the Simulus Flex group, smaller deformational forces were recorded compared to the Duran AnCore group, but the difference was not statistically significant (p = 0.52 and p = 0.06 for the septal-lateral and the commissure-commissure force measurements, respectively). CONCLUSIONS: The Simulus Flex ring showed significantly more remodeling capacity than the Duran AnCore ring, but the latter ring preserved the natural dynamics of the mitral valve to a greater degree. Insights into these biomechanical differences may facilitate strategies for surgical reconstruction in degenerative mitral valve disease, especially in patients with excessive amounts of tissue and who are at risk of systolic anterior motion of the mitral valve.

Remodeling Mitral Annuloplasty Ring Concept with Preserved Dynamics of Annular Height.

BACKGROUND AND AIM OF THE STUDY: The configuration of the native annulus changes from nearly flat in the diastolic phase to saddle-shaped in the systolic phase. The present study was conducted to test a novel remodeling annuloplasty ring with built-in septal-lateral fixation and commissural axial flexibility so as to maintain the change in annular saddle shape. The study aim was to evaluate the in-vivo biomechanical performance of the novel annuloplasty ring, compared with the native valve and a semi-rigid and rigid annuloplasty ring. METHODS: All measurements were performed in vivo using a porcine model. A total of 28 pigs (bodyweight ca. 80 kg) were randomized to four groups: (i) with no ring; (ii) with a novel remodeling ring; (iii) with a semi-rigid ring (Physio I Ring, Edwards Lifesciences); and (iv) with a rigid ring (Classic Annuloplasty Ring, Edwards Lifesciences). Force measurements were performed using a dedicated transducer to determine remodeling capacity of the annuloplasty rings. Geometric parameters were measured by implanting sonomicrometry crystals along the mitral annulus. RESULTS: All ring groups significantly restricted the cyclic change of the mitral annulus compared with the 'no-ring' group. The change and maximum value of the annular height were maintained for the novel ring but were significantly decreased for the rigid and semi-rigid rings compared with the 'no-ring' group. Mitral annular force measurements confirmed that the overall remodeling capacity of the novel ring was comparable with the conventional ring groups, and significantly higher in the septal-lateral direction compared to the semi-rigid ring. CONCLUSIONS: In-vivo geometry and force measurements indicated that the intended design features of the new device were successfully provided. The novel ring concept with remodeling properties, combined with the advantages of a flexible annuloplasty ring, is unique. The maintenance of annular saddle shape and cyclic change in annular height may be an important step towards improved mitral valve repair.

The efficacy of adhesiolysis on chronic abdominal pain: a systematic review.

INTRODUCTION: Abdominal adhesions are a frequent reason for chronic abdominal pain. The purpose of this systematic review was to investigate the evidence of performing laparoscopic adhesiolysis as a treatment for patients with chronic abdominal pain. METHODS: Medline, Embase, and The Cochrane Central Register of Controlled Trials were searched for trials performing lysis of adhesions on patients suffering from chronic abdominal pain. Clinical studies on patients being treated for chronic abdominal pain with surgical adhesiolysis were included. The main outcome of the study was the postoperative assessment of symptoms. The Newcastle-Ottawa scale was used for bias assessment of non-randomized studies while the Jadad score was used for the randomized controlled trials. RESULTS: A total of 25 studies were identified evaluating the efficacy of adhesiolysis in 1281 patients suffering from chronic abdominal pain. A total of 22 trials were identified as case-series and included no control group. Three studies were identified as randomized controlled trials (RCT). A benefit of the intervention varied from 16 to 88 % in the non-randomized studies, with the majority reporting pain relief in more than 50 % of their patients. However, analysis indicated a high risk of bias in most of the studies. The RCTs also showed variance, with one study showing benefit, one study showing benefit only in a subgroup in which the patients had dense and vascularized adhesions, and one study showed no difference between the intervention and control group. CONCLUSION: The identified studies showed promising but preliminary results of laparoscopic adhesiolysis as a treatment of chronic abdominal pain. The evidence for laparoscopic adhesiolysis is not sufficient to make definitive conclusions.

Circulatory responses to lower body negative pressure in young Afghans and Danes: implications for understanding ethnic effects on blood pressure regulation.

PURPOSE: We have previously shown that Afghans residing in Denmark for at least 12 years exhibit a lower 24-h ambulatory blood pressure compared to Danes. The purpose of this study was to test the hypothesis that the lower blood pressure reflects attenuated compensatory baroreflex responses in the Afghans. METHODS: On a controlled diet (2,822 cal/day, 55-75 mmol + 2 mmol Na+/kg/day), 12 young males of Afghan (Afghans) and 12 young males of Danish (Danes) origin were exposed to a two-step lower body negative pressure (LBNP) protocol of -20 and -50 mmHg, respectively, each of 10-min duration. RESULTS: Afghans had lower 24-h systolic blood pressure compared to Danes (115 ± 2 vs. 123 ± 1 mmHg, p < 0.05). Cardiac output and stroke volume were significantly lower in Afghans compared to Danes prior to and during each level of LBNP. However, it decreased to the same extent in both groups during LBNP. During LBNP of -20 mmHg, plasma noradrenaline concentration and plasma renin activity (PRA) increased significantly only in the Afghans. At LBNP of -50 mmHg plasma noradrenaline concentration and PRA both increased significantly and similarly in the two groups. CONCLUSION: The lower 24-h ambulatory blood pressure in the Afghans is probably caused by a lower stroke volume, which augmented the circulatory and vasoactive hormonal responses to LBNP in the Afghans. The lower stroke volume in Afghans residing in Denmark compared to that of matched native Danes remains to be explained.

Self-reported workplace bullying and subsequent risk of diagnosed mental disorders and psychotropic drug prescriptions: A register-based prospective cohort study of 75,252 participants.

BACKGROUND: Evidence concerning workplace bullying as a risk factor for mental disorders is currently limited to depressive disorders and mainly based on non-clinical assessments. This study aims to examine the prospective association of self-reported workplace bullying with different types of register-based hospital-diagnosed mental disorders and redeemed psychotropic drug prescriptions. METHODS: Using a cohort study design, we examined a pooled dataset of 75,252 participants from 14 questionnaire-based surveys conducted between 2004 and 2014. In the questionnaires, workplace bullying was measured by a single item. The questionnaires were linked to Danish registers on hospital-diagnosed mental disorders and redeemed psychotropic drug prescriptions up to 2016. Data were analysed by multivariate Cox proportional hazard models, including only participants without a history of mental disorders or prescriptions since 1995. RESULTS: After adjustment for sex, age, marital and socio-economic status, workplace bullying was associated with an excess risk of any mental disorder (HR 1.37; 95 % CI: 1.17-1.59) as well as mood disorders and neurotic, stress-related, and somatoform disorders. In stratified analyses, this association were statistically significant only among women. Workplace bullying was also associated with any psychotropic drug prescription (fully-adjusted HR 1.43; 95 % CI: 1.35-1.53). This association was observed in both sexes and for all prescriptions, including anxiolytics, hypnotics and sedatives, antidepressants, and nootropics. LIMITATIONS: Firm conclusions about sex-related differences cannot be drawn. Residual confounding by unmeasured factors such as personality cannot be ruled out. CONCLUSIONS: Workplace bullying was associated with higher risks of diagnosed mental disorders among women and psychotropic drug prescriptions in both sexes.

Perioperative anaesthesia by local infiltration following median sternotomy - a study protocol.

INTRODUCTION: Post-operative pain following open heart surgery is a clinical challenge usually requiring significant amounts of opioids. Long-acting local infiltration anaesthesia may effectively reduce post-operative opioid consumption and improve recovery. The trial is a publicly funded, double-blinded, randomised, placebo-controlled trial evaluating the effect of long-acting local infiltration anaesthesia in open heart surgery. METHODS: Two Danish centres are planning to randomise 100 patients undergoing coronary artery bypass grafting to treatment with long-acting infiltration anaesthesia or placebo. We compare an active solution of bupivacaine, adrenaline, clonidine and dexamethasone with saline placebo. The primary outcome measure is the accumulated opioid use within the first 24 post-operative hours. Secondary outcome measures include evaluation of respiratory function, patient-reported pain scores, mobilisation, opioid-associated side effects and long-term opioid consumption. CONCLUSION: This trial will define whether the use of long-acting infiltration anaesthesia during heart surgery may reduce acute and prolonged post-operative opioid consumption. Reduction of opioid-related adverse effects may improve recovery. FUNDING: The trial is supported by public grants (Dansk Selskab for Anæstesiologi og Intensiv Medicin: 40,000 DKK; Regionernes Medicin og Behandlingspulje 2022: 686,000 DKK). The work of I. S. Modrau is supported by an unrestricted grant from the Health Research Foundation of the Central Denmark Region. TRIAL REGISTRATION: EudraCT 2021-005886-41.

Night and evening shifts and risk of calling in sick within the next two days - a case-crossover study design based on day-to-day payroll data.

OBJECTIVE: Night and evening work is associated with risk of sickness absence, but little is known about the acute effects of these types of shifts on sickness absence. The aim of the current study is therefore to examine the risk of calling in sick within two days after a night or an evening shift. METHODS: By use of a case-crossover design, odds of calling in sick within two days after a night or an evening shift compared to day shifts were analyzed within the same person. Day-to-day information on shifts and sickness absence were derived from the Danish Working Hour Database on 44 767 cases. Data were analyzed using conditional logistic regression. The analyses were supplemented by extensive testing of methodological choices. RESULTS: Analyses showed higher odds of calling in sick after a night shift [odds ratio (OR) 1.22, 95% confidence intervak (CI) 1.14-1.30] and lower odds after an evening shift (OR 0.89, 95% CI 0.84-0.93) compared to day shifts within the same person. Testing of methodological choices suggested that in particular the duration of case and control periods, time between these periods along with the number of control periods affected the results. CONCLUSION: This large and unique within-person study among Danish hospital employees indicate that the risk of calling in sick is affected by the types of shifts, independently of sex, age, and time-invariant confounding. Extensive testing identified important methodological choices eg, length and number of included periods to consider when choosing the case-crossover design.

Trajectories of marginal part-time work and risk of depression. Does job or income insecurity mediate the relation?

OBJECTIVES: Working few hours a week, known as marginal part-time work, may increase both job and income insecurity, which have been linked to the risk of depression. This study examines the association between marginal part-time work and depression and the mediating role of job and income insecurity. METHODS: We included 30 523 respondents of the Danish Labor Force Survey (DLFS) between 2010 and 2017 and linked them to register-based information on weekly working hours, which was used to identify full-time workers and model group-based trajectories of marginal part-time. These data were linked with survey information on job and income insecurity, and register-based information on hospital-diagnosed depression or redeemed anti-depressant drugs in the following two years. We estimated hazard ratios (HR) by Cox proportional hazards models and conducted mediation analyses to estimate the natural direct and indirect effects using job and income insecurity as mediators. RESULTS: We identified three distinct trajectories of marginal part-time work: constant marginal part-time work, mobile towards marginal part-time work, and fluctuating in and out of marginal part-time work. Compared with full-time workers, the constant [HR 2.42, 95% confidence interval (CI) 1.83-3.20], mobile (HR 2.84, 95% CI 2.16-3.75), and fluctuating (HR 3.51, 95% CI 2.07-5.97) trajectories all had higher risks of depression. There was no evidence of mediation by either job (HR 1.02, 95% CI 0.92-1.12) or income (HR 0.98, 95% CI 0.89-1.08) insecurity. CONCLUSIONS: We found a higher risk of depression following marginal part-time work. The higher risk was not mediated by job or income insecurity.

Clinical Presentation and Outcome of Sinonasal Extraosseous Plasmacytoma in Denmark: A Nationwide Cohort From 1980 to 2017.

OBJECTIVES: Extraosseous plasmacytoma (EOP) is a rare plasma cell neoplasm that tends to convert to plasma cell myeloma (PCM) in about 11% to 35% of cases. It has a predilection for the upper respiratory tract, prototypically affecting the nasal cavity and paranasal sinuses. Contemporary first-line treatment is radiotherapy, with more recent studies showing an added benefit of combining radiation with surgery. In this cohort study, we aimed to examine clinical presentation, treatment, and prognosis for all patients nationwide from 1980 through 2017. Furthermore, we determined the size and extension of tumors, investigating the rate at which minimally invasive surgery would have been possible. METHODS: Patients were found in the national pathology registry, and all biopsies were collected for pathology review by a hematopathologist. We performed survival statistics for overall survival (OS), progression-free survival (PFS), and the cumulative incidence of conversion to PCM. RESULTS: Twenty-three patients were included. The median age was 65, and patients were primarily men (78%). Tumors were located in either the nasal cavity (57%), maxillary sinus (39%), or sphenoid sinus (4%). In most cases, the tumor was <5 cm (65%) without extension to adjacent structures (60%). The national incidence was 0.02/100,000 person-years, the median symptom duration until diagnosis was 5 months, and none of the patients presented with contiguous spread to regional lymph nodes. Stand-alone radiotherapy was the predominant treatment (61%). In the entire cohort, one patient died from the initial disease, and six patients died from either relapse of EOP or PCM. The 5-year OS, PFS, and conversion rate to PCM were 78%, 56%, and 23%, respectively. CONCLUSION: SN-EOP responds well to radiotherapy, but relapse and conversion to PCM were not uncommon and entailed a poor prognosis. Most tumors were endoscopically resectable and non-invasive, making the majority of tumors suitable for surgery as an addition to radiation.

Labor Market Affiliation of Marginal Part-Time Workers in Denmark-A Longitudinal Study.

This longitudinal study examined the labor market affiliations of marginal part-time workers (<15 working hours/week) compared with full-time workers (32−40 working hours/week) within gender and age groups. Analyses were based on 1,492,187 Danish employees with marginal part-time or full-time work at baseline using register data of working hours and labor market affiliation from the Labor Market Account. We used the Expected Labor Market Affiliation method within gender and age groups to estimate the time spent in different labor market states over a 5-year follow-up from 2012−2017. The multistate model included five recurrent labor market states: work, unemployment, long-term sickness absence, studying, and temporarily out, and the results were adjusted for education level, morbidity, and ethnicity. A marginal part-time worker generally had fewer days of work without social benefits and spent more days studying during follow-up compared with a full-time worker. In addition, marginal part-time workers ≥ 25 years old had more days of unemployment and more days of long-term sickness absence. These findings suggest that marginal part-time workers have fewer paid workdays without social benefits compared with full-time workers, depending on age. Further studies should explore whether marginal part-time work is a stepping stone into or out of the labor market.

Workplace bullying and risk of suicide and suicide attempts: A register-based prospective cohort study of 98 330 participants in Denmark.

OBJECTIVES: The aim of this study was to analyze whether individuals reporting exposure to workplace bullying had a higher risk of suicidal behavior, including both suicide attempt and death by suicide, than those not reporting such exposure. METHODS: Using a prospective cohort study design, we linked data from nine Danish questionnaire-based surveys (2004-2014) to national registers up to 31 December 2016. Exposure to workplace bullying was measured by a single item. Suicide attempts were identified in hospital registers and death by suicide in the Cause of Death Register. Among participants with no previous suicide attempts, we estimated hazard ratios (HR) and 95% confidence intervals (CI), adjusting for sex, age, marital status, socioeconomic status, and history of psychiatric morbidity. RESULTS: The sample consisted of 98 330 participants (713 798 person-years), 63.6% were women, and the mean age was 44.5 years. Of these participants, 10 259 (10.4%) reported workplace bullying. During a mean follow-up of 7.3 years, we observed 184 cases of suicidal behavior, including 145 suicide attempts, 35 deaths by suicide and 4 cases that died by suicide after surviving a suicide attempt. The fully-adjusted HR for the association between workplace bullying and suicidal behavior was 1.65 (95% CI 1.06-2.58). The HR for suicide attempts and death by suicide were 1.65 (1.09-2.50) and 2.08 (0.82-5.27), respectively. Analyses stratified by sex showed a statistically significant association between workplace bullying and suicidal behavior among men but not women. CONCLUSIONS: The results suggest that exposure to workplace bullying is associated with an elevated risk of suicidal behavior among men.

Characterization of the hemoglobins of the Australian lungfish Neoceratodus forsteri (Krefft).

We examined for the first time the hemoglobin components of the blood of the Australian lungfish, Neoceratodus forsteri and their functional responses to pH and the allosteric modulators adenosine triphosphate (ATP), guanosine triphosphate (GTP), 2,3-bisphosphoglyceric acid (BPG) and inositol hexaphosphate (IHP) at 25 degrees C. Lysates prepared from stripped, unfractionated hemolysate produced sigmoidal oxygen equilibrium curves with high oxygen affinity (oxygen partial pressure required for 50% hemoglobin saturation, p(50)=5.3 mmHg) and a Hill coefficient of 1.9 at pH 7.5. p(50) was 8.3 and 4.5 mmHg at pH 6 and 8, respectively, which corresponded to a modest Bohr coefficient (Delta log p(50)/Delta pH) of -0.13. GTP increased the pH sensitivity of oxygen binding more than ATP, such that the Bohr coefficient was -0.77 in the presence of 2 mmol L(-1) GTP. GTP was the most potent regulator of hemoglobin affinity, with concentrations of 5 mmol L(-1) causing an increase in p(50) from 5 to 19 mm Hg at pH 7.5, while the order of potency of the other phosphates was IHP>ATP>BPG. Three hemoglobin isoforms were present and each contained both alpha and beta chains with distinct molecular weights. Oxygen affinity and pH-dependence of isoforms I and II were essentially identical, while isoform III had a lower affinity and increased pH-dependence. The functional properties of the hemoglobin system of Neoceratodus appeared consistent with an active aquatic breather adapted for periodic hypoxic episodes.

In-vitro and in-vivo evaluation of a novel bioprosthetic pulmonary valve for use in congenital heart surgery.

BACKGROUND: Management of congenital malformations of the pulmonary artery and valve can be challenging. The severity often demands early intervention, which is rarely definitive due to the natural growth and multiple surgeries may be required. An artificial valve made entirely from biodegradable materials that will serve as a bioscaffold for host recellularization would be an attractive solution for these patients. Such valves have been experimentally evaluated with various results. In this study, a simple valve design supported by an absorbable proximal stabilization ring is evaluated both in-vitro and in-vivo. METHODS: From a 6.7 × 5.0 cm sheet of CorMatrix® tissue we created the valve as an inverted tubegraft with three sutured commissures. A non-closed ring of LactoSorb® basally supported the valve. The commissure height was 2 cm. Inserted as an interposition graft the valve was tested in an in-vitro model and an acute porcine model. Right ventricular and pulmonary artery pressures were recorded. RESULTS: The in-vitro testing indicated a proper opening and closure function of valve at physiological simulated hemodynamic conditions. The in-vivo evaluation showed a peak right ventricular pressure of 38 mmHg and a peak pulmonary artery pressure of 27 mmHg and thereby a peak valve gradient of 11 mmHg. The pulmonary pressure wave demonstrated a dicrotic notch indicating competence of the valve. CONCLUSION: This new pulmonary valve made entirely from biodegradable tissue worked in an acute setting and displayed a good hemodynamic profile. The valve gradient observed is equal to or superior of today's surgical treatment options.

Mitral annuloplasty ring with selective flexibility for septal-lateral contraction and remodelling properties.

OBJECTIVES: To develop and evaluate a novel mitral annuloplasty ring with selective flexibility for septal-lateral contraction and rigidity for septal-lateral dilatation in an acute porcine model. METHODS: The novel mitral annuloplasty ring was designed with slits in the luminal posterior segment and annular lateral segments. The slits were designed to allow inward motion during contraction and to block outward motion during dilation. The novel mitral annuloplasty ring was tested in vitro with a dedicated mechanical test bench, followed by in vivo characterization, using sonomicrometry and echocardiography for annular and leaflet geometry, in an acute porcine model. RESULTS: From the in vitro characterization, we verified that the ring could easily contract (0.7 mm/N) in the septal-lateral dimension, while dilatation was restrained (0.4 mm/N). In vivo characterization showed a cyclic range of 2.8 ± 0.0 mm for septal-lateral contraction. CONCLUSIONS: A novel saddle-shaped remodelling mitral annuloplasty ring was developed with selective flexibility for septal-lateral contraction and rigidity for septal-lateral dilatation. The advantages of this specific ring is that it re-establishes the coaptation plane, ensures leaflet mobility and septal-lateral flexibility and at the same time improves tissue adaptation and thereby decreases the risk of ring dehiscence and redilatation of the mitral annulus. This concept may prove beneficial for patients with ischaemic mitral valve regurgitation or degenerative valve disease.

Mid-term function and remodeling potential of tissue engineered tricuspid valve: Histology and biomechanics.

OBJECTIVE: Tricuspid valve reconstruction using a small intestinal submucosal porcine extracellular matrix (ECM) tube graft is hypothesized to be durable for six months and show signs of recellularization and growth potential. The purpose was to histologically and biomechanically test ECM valves before and after six months of implantation in pigs for comparison with native valves. METHODS: Ten 60 kg pigs were included, which survived tricuspid valve tube graft insertion. Anterior and septal tricuspid leaflets were explanted from all animals surviving more than one month and examined histologically (n = 9). Endothelialization, collagen content, mineralization, neovascularization, burst strength and tensile strength were determined for native valves (n = 5), ECM before implantation (n = 5), and ECM after six months (n = 5). RESULTS: Collagen density was significantly larger in ECM at implantation (baseline) compared to native leaflet tissue (0.3 ±â€¯0.02 mg/mm3 vs. 0.1 ±â€¯0.03 mg/mm3, p < .0001), but collagen density decreased and reached native leaflet collagen content, six months after ECM implantation (native vs. ECM valve at six months: 0.1 ±â€¯0.03 mg/mm3 vs. 0.2 ±â€¯0.05 mg/mm3, p = .8). Histologically, ECM valves showed endothelialization, host cell infiltration and structural collagen organization together with elastin generation after six months, indicating tissue remodeling and -engineering together with gradual development of a close-to-native leaflet structure without foreign body response. CONCLUSIONS: ECM tricuspid tube grafts were stronger than native leaflet tissue. Histologically, the acellular ECM tube grafts showed evidence of constructive tissue remodeling with endothelialization and connective tissue organization. These findings support the concept of tissue engineering and recellularization, which are prerequisites for growth.

The effect of different mitral annuloplasty rings on valve geometry and annular stress distribution†.

OBJECTIVES: To characterize the remodelling effects and deformational forces of normosized rigid, semirigid and flexible mitral annuloplasty rings after implantation in healthy pigs. METHODS: Measurements were performed in vivo with 80-kg porcine animals. Twenty-eight animals were randomized into a no ring group, a flexible ring group (Duran AnCore Ring, Medtronic, Minneapolis, MN, USA), a rigid ring group (Carpentier-Edwards Classic annuloplasty ring, Edwards Lifesciences, Irvine, CA, USA) and a semirigid ring group (Carpentier-Edwards Physio I annuloplasty ring, Edwards Lifesciences). Sonomicrometry crystals were implanted together with an annuloplasty ring and a dedicated mitral annular force transducer. The mitral annuloplasty rings were compared with respect to annular geometry and mitral annular forces. RESULTS: Cyclic changes in the mitral annulus (MA) circumference were significantly lower for all ring groups (flexible: 7 ± 3 mm, semirigid: 4 ± 2 mm and rigid: 2 ± 1 mm) compared to the no ring group (11 ± 5 mm), implying the remodelling capacity of all annuloplasty rings. The cyclic change of the MA area and the septa-lateral and inter-commissural distances were equal in the semirigid and rigid ring groups and significantly lower compared to the no ring and flexible ring groups, suggesting a stronger and equal remodelling effect in the semirigid and rigid ring groups. Forces measured in the transducer reflected the remodelling capacity of the annuloplasty rings and were in general lower for the semirigid and rigid ring groups compared to the no ring and flexible ring groups. Especially the forces in the inter-commissural direction were significantly reduced for the semirigid and rigid ring groups (semi-rigid: 1.4 ± 0.8 N, rigid: 1.2 ± 0.8 N) compared to the no ring and flexible ring groups (no ring: 3.0 ± 1.1 N, flexible: 3.4 ± 1.6 N). CONCLUSIONS: This study is the first to describe different remodelling effects and deformational forces of normosized mitral annuloplasty rings in vivo . Insights into the relationship between the remodelling effects and the accumulated forces of different mitral annuloplasty rings may have implications for ring selections in an aetiology-based mitral valve repair strategy. We propose the application of such a biomechanical approach for quantitative comparison of mitral annuloplasty rings and for future innovations on a rational basis.

Semi-rigid mitral annuloplasty rings improve myocardial stress adaptation compared to rigid rings: insights from in vitro and in vivo experimental evaluation.

OBJECTIVES: Investigate myocardial stress adaptation and remodelling capacity of a rigid and semi-rigid mitral annuloplasty ring. METHODS: The annuloplasty rings were characterized in vitro in a mechanical setup with tensile and compressive forces from 0 to 3 N. The rings were tested with and without fixation of the ring to imitate the effect of annular implantation. In vivo measurements were performed with 21 porcine animals randomized into: A no ring group, a rigid ring group (Classic Annuloplasty Ring TM , Edwards Lifesciences) and a semi-rigid ring group (Physio I Annuloplasty Ring, Edwards Lifesciences). The rings were implanted together with a force transducer and sonomicrometry was used for geometry measurements. RESULTS: The flexibility range of the semi-rigid ring was 7.6 and 2.4 mm in the septal-lateral and commissural direction, respectively. With fixation the flexibility was reduced to 1.0 and 0.6 mm, similar to the rigid ring without fixation. In vivo measurements indicated that the rigid and semi-rigid rings equally restrict the annular movement. Septal-lateral flexibility of the semi-rigid ring was not observed. Both rings induced force absorption in the ring and sutures due to the annular fixation. The absorbed forces were significantly lower for the semi-rigid ring in the posterior segment and septal-lateral direction. CONCLUSIONS: This study demonstrates the importance of correct fixation when characterizing annuloplasty rings. The annular movement of the semi-rigid ring was similar to the rigid ring when implanted at the mitral annulus as confirmed in vitro . Despite this the semi-rigid ring demonstrated a favourable stress adaptation which could potentially decrease the risk of ring dehiscence.