Permanent pacemaker insertion postmitral surgery: Do the atrial access and the origin of the sinoatrial node artery matter?

BACKGROUND AND AIM OF THE STUDY: To determine whether the type of atrial access to the mitral valve (left atriotomy, superior trans-septal, or limited trans-septal) influenced postoperative permanent pacemaker implantation and to investigate the effect of the sinoatrial (SA) node artery origin (right coronary or circumflex arteries) on the rate of pacemaker insertion. METHODS: We retrospectively reviewed consecutive cases of patients who had mitral valve surgery at the Trent Cardiac Centre (2008-2016). The primary outcome was the incidence of permanent pacemaker insertion. The data were analyzed using univariate then binary multivariate regression analysis. RESULT: Four hundred sixty nine patients had mitral valve surgery. The mean age was 66.5 ± 12.3 years and 47.5% were female. One hundred fifty patients (32%) had mitral valve surgery via the standard left atriotomy approach, while 226 (48.2%) and 93 (19.8%) cases were performed using the limited trans-septal and superior trans-septal approaches, respectively. Concomitant tricuspid valve surgery was carried out in 33 cases (7%). The overall rate of pacemaker implantation was 5.3%. On univariate analysis, only age (≥70 years old) and concomitant tricuspid valve surgery were significant predictors of postoperative pacemaker insertion, while on multivariate analysis only age (≥70 years old) remained as a predictor. The type of atrial incision and the origin of the SA node artery did not affect the rate of pacemaker implantation. CONCLUSION: The type of atrial approach to the mitral valve and the origin of the SA node artery did not influence the incidence of postoperative permanent pacemaker insertion.

Atrial approaches to the mitral valve: is there a difference in postoperative rhythm disturbance and permanent pacemaker implantation?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether there was a difference in postoperative outcomes [namely permanent pacemaker (PPM) insertion, rhythm disturbance, reoperation for bleeding, hospital stay and in-hospital mortality] between trans-septal or superior (extended) trans-septal (STS) approaches in comparison with the conventional left atriotomy (LA) used in mitral valve surgery. Using the reported search strategy, 353 papers were found of which 11 represented the best evidence to answer the clinical question. The authors, journal, year and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Two papers compared all 3 atrial incisions with neither showing a difference in PPM implantation rate, whereas 2 papers compared just the trans-septal with the LA approach, again both finding no significant difference in PPM implantation. Seven studies compared the STS approach with the LA approach with regard to PPM implantation; 1 study showed that the STS approach was an independent risk factor for PPM implantation, PPM insertion was not necessary in 2 studies and there was no difference in PPM insertion in 4 studies. Postoperative junctional rhythm was studied in 5 papers that compared the STS approach with the LA approach; junctional rhythm was more prevalent in the STS approach in 2 studies, albeit transient, whereas 3 papers did not show a significant difference. Mortality, hospital stay and re-exploration for bleeding did not differ among the 3 groups.

Prosthetic Valve Endocarditis Following Dental Extractions.

Early-onset prosthetic valve endocarditis is a serious complication of valve replacement. We present two cases of early-onset prosthetic valve endocarditis caused by species of the anaerobic organism Prevotella, and discuss the issue of dental extraction prior to valve surgery. doi: 10.1111/jocs.12732 (J Card Surg 2016;31:321-323).

Racial and Gender Influences on Pass Rates for the UK and Ireland Specialty Board Examinations.

INTRODUCTION: We explored effects of gender, ethnic origin, first language, and training status on scores in the Intercollegiate Specialty Board examinations in the UK and Ireland across the computer-marked written section and in the face-to-face oral and clinical section. METHODS: Demographic characteristics and examination results from 9987 attempts across 177 sittings from 2009 to 2013 were analyzed in an analysis of variance by training status, gender, ethnic origin, first language, and section (computer-marked multiple-choice examination vs face-to-face oral and clinical examination). RESULTS: We found increasing alignment between examiner and candidate characteristics during this period, with a 50% increase in examiners of Asian ethnic origin and a 60% increase in examiners whose first language is not English. The strongest factor in the analysis of variance was training status (F[2, 9818] = 27.67, p < 0.001), with candidates in training significantly outperforming others. Within "core candidates" (first attempt, in training), we found significant main effects for ethnic origin (F[5, 4809] = 2.36, p = 0.04), and first language (F[2, 4809] = 5.29, p = 0.003), but no interaction effects between these factors and section (both F < 1, p > 0.05). CONCLUSIONS: Training status was the most important factor in candidates' results. Although the analysis showed significant effects of ethnic origin and first language within "core candidates," these differences were statistically indistinguishable between the 2 sections of the examination, suggesting that the differential attainment by these factors cannot be attributed to examiner bias in a face-to-face examination.

Severe Mitral Regurgitation Secondary to Atresia of the Posterior Mitral Valve Leaflet in the Adult: Is Repair Always Best Practice?

We describe a case of a 66-year-old woman with severe mitral regurgitation secondary to posterior leaflet atresia of the mitral valve. Perioperative transesophageal echocardiography suggested the possibility of an absent posterior leaflet with complete prolapse of the anterior leaflet. We questioned the functional outcome if repair was attempted; therefore, mitral valve replacement was performed. We present a case outlining the successful management of this rare condition in an adult as well as a review of current literature.

Early prosthetic valve degeneration with Mitroflow aortic valves: determination of incidence and risk factors†.

OBJECTIVES: We describe a cluster of early valve degeneration (EVD) in a series of 281 Mitroflow valves implanted during 1999-2013. Patients with EVD were identified as having symptomatic stenosis or regurgitation within 6 years of implantation leading to reoperation. METHODS: Freedom from reoperation was estimated by Kaplan-Meier actuarial analysis. Patient and valve characteristics in the EVD group were compared with those without using univariate and Cox proportional hazard multivariate regression analysis. RESULTS: The rate of actuarial freedom from reoperation was 97% at 6 years and 92.5% at 10 years. The linearized rate of reoperation was 0.7% per patient-year. Ten patients required repeat surgery for EVD. Reoperation occurred from 2 years of implantation in patients with a mean age of 60, compared with 70 in those without EVD. Causes of explantation were stenosis (8), regurgitation (1) and mixed disease (1). The age was the only significant predictor of early degeneration; P = 0.03, hazard ratio = 2.89. Other factors analysed were atrial fibrillation, hypertension, chronic obstructive pulmonary disease, stroke, diabetes, preoperative angina, poor left ventricular function, renal dysfunction and extracardiac arteriopathy. There were no significant postoperative complications or operative mortality in those patients undergoing repeat surgery. CONCLUSIONS: There is an unexplained incidence (3.6%) of EVD resulting in explantation in some patients at 2 years after surgery. Mitroflow valves may not be suited to a younger age population.

Precursor transformation during molecular oxidation catalysis with organometallic iridium complexes.

We present evidence for Cp* being a sacrificial placeholder ligand in the [Cp*Ir(III)(chelate)X] series of homogeneous oxidation catalysts. UV-vis and (1)H NMR profiles as well as MALDI-MS data show a rapid and irreversible loss of the Cp* ligand under reaction conditions, which likely proceeds through an intramolecular inner-sphere oxidation pathway reminiscent of the reductive in situ elimination of diolefin placeholder ligands in hydrogenation catalysis by [(diene)M(I)(L,L')](+) (M = Rh and Ir) precursors. When oxidatively stable chelate ligands are bound to the iridium in addition to the Cp*, the oxidized precursors yield homogeneous solutions with a characteristic blue color that remain active in both water- and CH-oxidation catalysis without further induction period. Electrophoresis suggests the presence of well-defined Ir-cations, and TEM-EDX, XPS, (17)O NMR, and resonance-Raman spectroscopy data are most consistent with the molecular identity of the blue species to be a bis-µ-oxo di-iridium(IV) coordination compound with two waters and one chelate ligand bound to each metal. DFT calculations give insight into the electronic structure of this catalyst resting state, and time-dependent simulations agree with the assignments of the experimental spectroscopic data. [(cod)Ir(I)(chelate)] precursors bearing the same chelate ligands are shown to be equally effective precatalysts for both water- and CH-oxidations using NaIO4 as chemical oxidant.

Advanced care nurse practitioners can safely provide sole resident cover for level three patients: impact on outcomes, cost and work patterns in a cardiac surgery programme.

OBJECTIVES: There are significant pressures on resident medical rotas on intensive care. We have evaluated the safety and feasibility of nurse practitioners (NPs) delivering first-line care on an intensive care unit with all doctors becoming non-resident. Previously, resident doctors on a 1:8 full-shift rota supported by NPs delivered first-line care to patients after cardiac surgery. Subsequently, junior doctors changed to a 1:5 non-resident rota and NPs onto a 1:7 full-shift rota provided first-line care. METHODS: A single centre before-and-after service evaluation on cardiac intensive care. KEY MEASURES FOR IMPROVEMENT: mortality rates, surgical trainee attendance in theatre and cost before and after the change. After-hour calls by NPs to doctors and subsequent actions were also audited after the change. RESULTS: The overall mortality rates in the 12 months before the change were 2.8 and 2.2% in the 12 months after (P = 0.43). The median [range] logistic EuroSCORE was 5.3 [0.9-84] before and 5.0 [0.9-85] after the change (P = 0.16). After accounting for the risk profile, the odds ratio for death after the change relative to before was 0.83, 95% confidence interval 0.41-1.69. Before the change, a surgical trainee attended theatre 467 of 702 (68%) cases. This increased to 539 of 677 (80%) cases after the change (P < 0.001). The annual cost of staffing the junior doctor and NP programme before the change was £933 344 and £764 691 after. In the year after the change, 192 after-hour calls were made to doctors. In 57% of cases telephone advice sufficed and doctors attended in 43%. CONCLUSIONS: With adequate training and appropriate support, resident NPs can provide a safe, sustainable alternative to traditional staffing models of cardiac intensive care. Training opportunities for junior surgeons increased and costs were reduced.

Defining acute aortic syndrome after trauma: Are Abbreviated Injury Scale codes a useful surrogate descriptor?

BACKGROUND: The severity and location of injuries resulting from vehicular collisions are normally recorded in Abbreviated Injury Scale (AIS) code; we propose a system to link AIS code to a description of acute aortic syndrome (AAS), thus allowing the hypothesis that aortic injury is progressive with collision kinematics to be tested. METHODS: Standard AIS codes were matched with a clinical description of AAS. A total of 199 collisions that resulted in aortic injury were extracted from a national automotive collision database and the outcomes mapped onto AAS descriptions. The severity of aortic injury (AIS severity score) and stage of AAS progression were compared with collision kinematics and occupant demographics. Post hoc power analyses were used to estimate maximum effect size. RESULTS: The general demographic distribution of the sample represented that of the UK population in regard to sex and age. No significant relationship was observed between estimated test speed, collision direction, occupant location or seat belt use and clinical progression of aortic injury (once initiated). Power analysis confirmed that a suitable sample size was used to observe a medium effect in most of the cases. Similarly, no association was observed between injury severity and collision kinematics. CONCLUSION: There is sufficient information on AIS severity and location codes to map onto the clinical AAS spectrum. It was not possible, with this data set, to consider the influence of collision kinematics on aortic injury initiation. However, it was demonstrated that after initiation, further progression along the AAS pathway was not influenced by collision kinematics. This might be because the injury is not progressive, because the vehicle kinematics studied do not fully represent the kinematics of the occupants, or because an unknown factor, such as stage of cardiac cycle, dominates. LEVEL OF EVIDENCE: Epidemiologic/prognostic study, level IV.

Switching off electron transfer reactions in confined media: reduction of [Co(dipic)2]- and [Co(edta)]- by hexacyanoferrate(II).

The kinetics of reduction of two cobalt(III) complexes with similar redox potentials by hexacyanoferrate(II) were investigated in water and in reverse micelle (RM) microemulsions. The RMs were composed of water, surfactant [(sodium(bis(2-ethylhexylsulfosuccinate)), NaAOT], and isooctane. Compared to the reaction in water, the reduction rates of (ethylenediaminetetraacetato)cobaltate(III) by hexacyanoferrate(II) were dramatically suppressed in RM microemulsions whereas a slight rate increase was observed for reduction of bis-(2,6-dipicolinato)cobaltate(III). For example, the ferrocyanide reduction of [Co(dipic)(2)](-) increased from 55 M(-1) s(-1)in aqueous media to 85 M(-1) s(-1) in a w(o) = 20 RM. The one-dimensional (1-D) and two-dimensional (2-D) (1)H NMR and FT-IR studies are consistent with the reduction rate constants of these two complexes being affected by their location within the RM. Since reduction of [Co(edta)](-) is switched off, in contrast to [Co(dipic)(2)](-), these observations are attributed to the penetration of the [Co(edta)](-) into the interfacial region of the RM whereas [Co(dipic)(2)](-) is in a region highly accessible to the water pool and thus hexacyanoferrate(II). These results demonstrated that compartmentalization completely turns off a redox reaction in a dynamic microemulsion system by either reactant separation or alteration of the redox potentials of the reactants.

Preoperative intra aortic balloon pumps in patients undergoing coronary artery bypass grafting.

BACKGROUND: The intra aortic balloon pump (IABP) is a mechanical assist device which improves cardiac function. The device has a well-established place in algorithms for managing low cardiac output following cardiac surgery. There is increasing evidence that certain cardiac surgery patients benefit from a period of preoperative augmentation with the intra aortic balloon pump. OBJECTIVES: To determine the effect of the preoperative intra aortic balloon pump on mortality and morbidity in a number of different patients groups undergoing coronary artery bypass grafting. SEARCH STRATEGY: The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 3, 2009), MEDLINE (2000 to August 2009), EMBASE (1998 to August 2009), BIOSIS previews (1969 to August 2009) and ISI Proceedings (1990 to August 2009) were searched. References and ongoing registers of studies were checked. No language restrictions were applied. SELECTION CRITERIA: Randomised controlled trials (RCTs) of any size or length were included. DATA COLLECTION AND ANALYSIS: Papers were assessed for inclusion by two authors independently and differences were settled by consensus with a third author. Date are presented in the form of odds ratios (OR) and 95% confidence intervals (CI). MAIN RESULTS: Six trials were included (five on-pump and one off-pump). This update adds the results of one further trial. Data from a total of 255 patients were included in the meta-analysis of mortality outcomes; all on-pump. Generally, the patients were considered as "high risk" and 132 were treated preoperatively with IABP and 123 served as controls. There were four hospital deaths in the intervention arm and 23 in the non-intervention arm (OR 0.18, 95% CI 0.08 to 0.41; P<0.0001). In a subgroup analysis, low cardiac index (<2.0 L/min/m(2)) was noted in 21 out of 105 patients in the treatment arm and 59 patients out of 88 in the non-treatment arm (OR 0.14, 95% CI: 0.08 to 0.25; P<0.00001). An off-pump versus on-pump analysis was not possible due to the limited number of off-pump studies. However a single well-conducted RCT suggested favourable effect of the preoperative IABP in off-pump patients. AUTHORS' CONCLUSIONS: Evidence suggests that preoperative IABP may have a beneficial effect on mortality and morbidity in specific high risk patient groups undergoing coronary artery bypass grafting, however there are many problems with the quality, validity and generalisability of the trials. However, the available evidence is not robust enough to extend the use of IABP to truly elective, high risk patients. Defining more precisely which patient groups may benefit would be the challenge for the future.

Three strikes--don't die of a broken heart.

There are multiple layers of complexity in prevention of vehicle related blunt traumatic aortic rupture (BTAR), many of which are enshrined within government policy and car design. We present a 'layers of protection analysis' (LOPA) based loosely on original work by Professor John Doyle, which describes these attempts to 'design out' the risk of BTAR following a vehicle collision. We have modified this approach to include a physiological dimension suggesting that this may be a factor in susceptibility to aortic injury following trauma. Understanding processes involved in BTAR following vehicle collisions is key to designing preventative processes.

Blunt trauma and acute aortic syndrome: a three-layer finite-element model of the aortic wall.

OBJECTIVE: The exact process by which blunt trauma to the aorta produces a typical characteristic lesion set of primary, transverse, intimal injury remains unknown. The likely cause is a combination of intraluminal hypertension and mechanical deformation. We set about creating a three-layer finite-element model of the aorta. We hypothesised that deformation of the aorta through tension, torsion and bending would have differential effects on the constitutive layers of the aorta and this differential stress strain pattern would help to explain the mechanism of this injury. METHODS: A finite-element model of the aorta was created with three distinct layers representing tunica intima, media and adventitia. A rubble-like material model in the commercial dynamic finite-element package LS-DYNA was adopted. Numerical methods for considering the interaction between aortic tissue (solid) and blood (fluid) were defined using arbitrary Lagrangian Eulerian methods. Simulations of mechanical deformation including tension, torsion and bending were applied with loading set at 1m/s and intraluminal blood pressure rising from 86.6mmHg to 146mmHg. The simulations were run until material failure. The role of blood within these simulations was explored. RESULT: Our initial simulations confirmed the functionality of the three-layer finite-element model of the aorta with behaviour as expected from previously published experimentation. The addition of mechanical loading through torsion, tension and bending resulted in failure of the aorta at significantly lower mean blood pressures than without. Temporal and spatial aspects of failure were distinct for each method of loading. Bending resulted in rapid primary adventitial failure while tension and torsion resulted in a relatively delayed primary intimal failure. Blood flow altered the stress strain characteristics within the model. CONCLUSIONS: This work confirms the feasibility of using a three-layer FE model of the aorta. Our data suggest that the relative contribution of intraluminal hypertension to BTAR is lower in the presence of complex loading by tension, torsion and bending. In addition, failure of the aorta is load dependent with bending causing a relatively early primary adventitial failure, while tension and torsion result in a relatively delayed primary intimal failure.

Regional wall mechanics and blunt traumatic aortic rupture at the isthmus.

OBJECTIVE: Blunt traumatic aortic injury (BTAI) is part of a spectrum of diseases termed acute aortic syndrome that accounts for 20% of road traffic accident related deaths. The injury has a complex aetiology with a number of putative mechanisms accounting for the injury profile, characteristics of which include a transverse primary intimal tear located at the aortic isthmus. We hypothesised that an understanding of regional aortic wall mechanics would contribute to an understanding of the aetiology of BTAI. METHODS: Samples of porcine aorta were prepared from ascending (A), descending (D) and peri-isthmus regions (I). A histological analysis of aortic wall architecture was performed at the site of attachment of the ligamentum arteriosum. Samples were mounted in a bubble inflation clamping rig, connected via a solenoid release valve to a compressed air reservoir. Using a pressure transducer and high-speed camera (1000fps) we collected data on wall thickness, rupture pressure and radial extension, allowing calculation of ultimate tensile stress. RESULTS: Histological analysis at the point of attachment of the ligamentum arteriosum to the isthmus shows some heterogeneity in cellular architecture extending deep into the tunica media. Wall thickness was significantly different between the three sampled regions (A>I>D, p<0.05). However, we found no difference in absolute rupture pressure between the three regions (kPa), (A, 300+/-28.9; I, 287+/-48.3; D, 321+/-29.6). Radial extension (cm) was significantly greater in A vs I (p<0.05), (A, 1.85+/-0.114; I, 1.66+/-0.109; D, 1.70+/-0.138). Ultimate tensile stress (kPa), (A, 3699+/-789; I, 3248+/-1430; D, 4260+/-1626) was significantly greater in D than I (p<0.05). CONCLUSIONS: The mechanism of blunt traumatic aortic rupture is not mechanically simple but must correspond to a complex combination of both relative motion of the structures within the thorax and local loading of the tissues, either as a result of their anatomy or due to the nature of the impact. A pressure spike alone is unlikely to be the primary cause of the peri-isthmus injury but may well be a contributory prerequisite.

Unusual case of two synchronous intracavitary primary cardiac tumors.

We report a patient who had two histologic and distinct synchronous intracardiac tumors, with one located in each atrium. The second tumor was missed on intraoperative transesophageal echocardiography, but was discovered when the right atrium was opened using a bi-atrial trans-septal approach. We discuss the merits of this approach and the role of additional imaging for cardiac tumors.

High spin d5 complexes of tris(6-hydroxymethyl-2-pyridylmethyl)amine (H3L): hepta-coordinated [Mn(H3L)]Cl2 and linear trinuclear [Fe3L2](ClO4)3.

Reaction of MnCl(2).4H(2)O with H(3)L (H(3)L = tris(6-hydroxymethyl-2-pyridylmethyl)amine) in methanol gives hepta-coordinated [Mn(H(3)L)]Cl(2) involving attachment of Mn(II) to all four nitrogens and three hydroxymethyl arms. Reaction of H(3)L with Fe(ClO(4))(2).6H(2)O in CH(3)CN in the presence of NaO(2)CC(6)H(5) in an attempt to make [Fe(III)OH(H(3)L)(O(2)CC(6)H(5))](ClO(4)), a putative model for soybean lipoxygenase-1, instead gave rise to the linear triiron(III) complex [Fe(3)L(2)](ClO(4))(3) with all three hydroxymethyl arms deprotonated and forming three alkoxide bridges between each Fe(III) centre. The central Fe(III) is hexa-coordinated to only the alkoxide bridges and flanked by two hepta-coordinated iron(III) centres analogous to the Mn(ii) complex. [Fe(3)L(2)](ClO(4))(3) exhibits two reversible 1e(-) reductions to mixed-valence [Fe(3)L(2)](2+) and [Fe(3)L(2)](+) forms. Structure data and magnetochemistry on [Fe(3)L(2)](ClO(4))(3) reveals the tightest Fe-O-Fe angle (87.4 degrees ) and shortest Fe...Fe distance (2.834 A) yet found for any weakly antiferromagnetically-coupled high spin alkoxide-bridged di- or triiron(iii) system and challenges current theories involved in correlating the extent/nature of magnetic interactions in such systems based on Fe-O(bridge) distances and Fe-O-Fe angles. The central hexa-alkoxide coordinated Fe(III) is novel and shows a remarkable resistance towards reduction to Fe(II).

The way the intra-aortic balloon catheter moves within the aorta as a possible mechanism of balloon associated morbidity.

This study set off to investigate which mode of weaning of an intra-aortic balloon pump (IABP) produces more aortic trauma. With the use of a perfusion pump, an intact porcine aorta with an IABP in situ, was studied. Angioscopic images of the interior of the aorta were obtained. Whilst keeping steady blood pressure and flow, an 'aortic impact score' was calculated. Endoscopically there is a 'whipping' effect of the balloon shaft on the lateral aortic wall, which appears to be prominent in 1:3 mode. The aortic impact score at 0.5, 6 and 12 h during the experiments was: (1) When weaning by mode: a) 1:1 3.3+/-0.6, 4.0+/-1.0 and 4.3+/-0.6; b) 1:2 4.7+/-0.6, 6.7+/-0.6 and 7.0+/-0.0; c) 1:3 8.7+/-0.6, 11+/-1.0 and 11.7+/-0.6. (2) Weaning by augmentation: a) 75% 2.3+/-0.6, 2.7+/-0.6 and 3.0+/-0.0; b) 50% 1.3+/-0.6, 1.3+/-0.6 and 1.7+/-0.6. An increasing score was observed while weaning by mode (P<0.05). The 1:3 mode produces marked intimal disruption that worsens with time.

Combined experimental and theoretical approach to the study of structure and dynamics of the most inert aqua ion [Ir(H2O)6]3+ in aqueous solution.

Quantitative determination of the hydration structure of hexaaquairidium(III), [Ir(H2O)6]3+, in aqueous solution, the most inert aqua ion known, has been achieved for the first time by a combined experimental-theoretical approach employing X-ray absorption spectroscopy and molecular dynamics (MD) simulations. The Ir LIII-edge extended X-ray absorption fine structure (EXAFS) spectrum and LI-, LII-, and LIII-edge X-ray absorption near-edge structure (XANES) spectra of three concentrations of [Ir(H2O)6]3+ in perchloric acid media were measured. To carry out classical MD simulations of the aqua ion in water, a new set of first-principles Ir-H2O intermolecular potentials, based on the hydrated ion concept, has been developed. Structural, dynamics, and energetic properties have been obtained from the analysis of the statistical trajectories generated. The Ir-O radial distribution function shows two well-defined peaks at 2.04 +/- 0.01 and 4.05 +/- 0.05 A corresponding to the first and second hydration shell, respectively; the fundamental frequencies for the aqua ion in water are well reproduced by the MD simulation, and its dynamic properties are similar to the experimental values corresponding to other hexahydrated trivalent ions. Particular attention has been devoted to the experimental determination of the second hydration shell. It has been found that contrarily to what expected on the basis of the inertness of the Ir3+ aquaion, the detection of the second hydration shell by EXAFS for this cation is more difficult than for others less inert aqua ions such as Cr3+ or Rh3+. But when combined with MD simulations it is possible to confirm the coordination distance for this shell at 4.1 +/- 0.1 A. In addition, the computation of LI, LII and LIII XANES spectra were carried out using the structural information obtained from MD. These computations allowed the assignment of special features of the spectra to the second hydration shell on a quantitative basis. Therefore, interestingly XANES spectra have given a stronger support to the second hydration shell than EXAFS. The fit of the LIII-edge EXAFS gives an accurate description of the first hydration shell structure in aqueous solution. The value for Ir-O first shell is 2.04 +/- 0.01 A. The statistical information available with the MD results has allowed the analysis of the standard deviation associated with the computation of the XANES spectrum. It is shown that the standard deviation increases with the number of hydration shells and this increase is nonuniform along the average spectrum.