Fluid dynamics simulation of right ventricular outflow tract oversizing.

OBJECTIVES: Repair of the right ventricular outflow tract (RVOT) in paediatric cardiac surgery remains challenging due to the high reoperation rate. Intimal hyperplasia and consequent arteriosclerosis is one of the most important limitation factors for graft durability. Since local shear stress and pressure are predictive elements for intimal hyperplasia and wall degeneration, we sought to determine in an oversized 12-mm RVOT model, with computed fluid dynamics simulation, the local haemodynamical factors that may explain intimal hyperplasia. This was done with the aim of identifying the optimal degree of oversizing for a 12-mm native RVOT. METHODS: Twenty domestic pigs, with a weight of 24.6 ± 0.89 kg and a native RVOT diameter of 12 ± 1.7 mm, had valve conduits of 12, 16, 18 and 20 mm implanted. Pressure and flow were measured at 75, 100 and 125% of normal flow at RVOT at the pulmonary artery, pulmonary artery bifurcation and at the left and right pulmonary arteries. Three-dimensional computed fluid dynamics (CFD) simulation in all four geometries in all flow modalities was performed. Local shear stress and pressure conditions were investigated. RESULTS: Corresponding to 75, 100 and 125% of steady-state flow, three inlet velocity profiles were obtained, 0.2, 0.29 and 0.36 m/s, respectively. At inflow velocity profiles, low shear stress areas, ranged from 0 to 2 Pa, combined with high-pressure areas ranging from 11.5 to 12.1 mmHg that were found at distal anastomosis, at bifurcation and at the ostia of the left and right pulmonary arteries in all geometries. CONCLUSIONS: In all three oversized geometries, the local reparation of shear stress and pressure in the 16-mm model showed a similar local profile as in the native 12 mm RVOT. According to these findings, we suggest oversizing the natural 12-mm RVOT by not more than 4 mm. The elements responsible for wall degeneration and intimal hyperplasia remain very similar to the conditions present in native RVOT.

Significance of an isolated new right bundle branch block in a patient with chest pain.

Chest pain is a common presenting symptom in emergency departments, and a typical manifestation of acute myocardial infarction (AMI). Recognition of ECG changes in AMI is essential for timely diagnosis and treatment. Right bundle branch block (RBBB) may be an isolated sign of AMI, and was previously considered as a criterion for fibrinolytic therapy. Since the most recent European Society of Cardiology and American Heart Association guidelines in 2013, RBBB alone is no longer considered a diagnostic criterion of AMI, even if it occurs in the context of acute chest pain, as RBBB does not usually interfere with the interpretation of ST-segment alteration. Our case illustrates an acute septal myocardial infarction with an isolated RBBB, and thus the importance of recognising this pattern in order to permit timely diagnosis and treatment.

A New Symptom, 'Palinendophonia', Associated with Pure Verbal Palinacousis Induced by a Right Inferior Temporal Lesion.

We describe the case of a patient with pure verbal palinacousis and perseveration of inner speech after a right inferior temporal lesion. The superior temporal lobe, including the superior temporal sulcus and the interhemispheric connection between the 2 superior temporal lobes, explored by tractography, were preserved. These regions are involved in voice processing, verbal short-term memory and inner speech. It can then be hypothesised that abnormal activity in this network has occurred. Palinacousis and 'palinendophonia', a term proposed for this symptom not previously reported, may be due to common cognitive processes disorders involved in both voice hearing and inner speech.

Right heart ischemia in cases of sepsis.

Data from the literature suggest that cases of sepsis complicated by right ventricular (RV) dysfunction have poorer prognosis. In these cases progressive hypoperfusion associated to increasing, injury-related, pulmonary vascular resistance account for RV ischemia. In the present analysis, we wanted to evaluate whether prevalent RV cardiac ischemic damage could be detected in a series of fatal sepsis cases. We retrospectively investigated 20 cases of sepsis that underwent forensic autopsy (study group-11♀, 9♂, mean age 57 years) and compared them to a group of 20 cases of hanging (hanging group-4 ♀, 16 ♂, mean age 44 years) as well as to a group of 20 cases of myocardial infarction (MI group-9 ♀, 11 ♂, mean age 65 years), as examples of cardiac damage due to global hypoxia during agony and ischemic damage, respectively. We performed immunohistochemistry with the antibodies anti-fibronectin and C5b-9. The reactions were semiquantitively classified and the groups were compared. In 30% of the cases of sepsis prevalent RV ischemic damage could be detected with the antibody anti-fibronectin. This expression was significantly different from that observed in cases of MI (p=0.028) and hanging (p<0.001). Our study showed that, in cases of fatal sepsis, prevalent RV ischemic damage occurred in a substantial minority of cases.

Right ventricular rupture due to recurrent mediastinal infection with a closed chest.

Right ventricular (RV) rupture in cases of mediastinitis following cardiac surgery is a rare and dangerous complication. Bleeding from the right ventricle occurs mainly after sternal reopening, due to either iatrogenic manipulation (wire removal, lesions due to wiring maneuvers) or mechanical shearing forces, producing direct injury. We present a case of RV wall perforation due to infection in a recurrent postoperative mediastinitis with a closed chest. The current literature on treatment of postoperative mediastinitis is also reviewed.

Connectivity and tissue microstructural alterations in right and left temporal lobe epilepsy revealed by diffusion spectrum imaging.

Focal epilepsy is increasingly recognized as the result of an altered brain network, both on the structural and functional levels and the characterization of these widespread brain alterations is crucial for our understanding of the clinical manifestation of seizure and cognitive deficits as well as for the management of candidates to epilepsy surgery. Tractography based on Diffusion Tensor Imaging allows non-invasive mapping of white matter tracts in vivo. Recently, diffusion spectrum imaging (DSI), based on an increased number of diffusion directions and intensities, has improved the sensitivity of tractography, notably with respect to the problem of fiber crossing and recent developments allow acquisition times compatible with clinical application. We used DSI and parcellation of the gray matter in regions of interest to build whole-brain connectivity matrices describing the mutual connections between cortical and subcortical regions in patients with focal epilepsy and healthy controls. In addition, the high angular and radial resolution of DSI allowed us to evaluate also some of the biophysical compartment models, to better understand the cause of the changes in diffusion anisotropy. Global connectivity, hub architecture and regional connectivity patterns were altered in TLE patients and showed different characteristics in RTLE vs LTLE with stronger abnormalities in RTLE. The microstructural analysis suggested that disturbed axonal density contributed more than fiber orientation to the connectivity changes affecting the temporal lobes whereas fiber orientation changes were more involved in extratemporal lobe changes. Our study provides further structural evidence that RTLE and LTLE are not symmetrical entities and DSI-based imaging could help investigate the microstructural correlate of these imaging abnormalities.

Assessment of intima-media complex in carotid, femoral and right subclavian arteries for early investigation of atherosclerosis in HIV-infected patients

Objective To compare automatic and manual measurements of intima-media complex (IMC) in common carotid, common femoral and right subclavian arteries of HIV-infected patients in relation to a control group, taking into consideration the classical risk factors for atherosclerosis. Materials and Methods The study sample comprised 70 HIV-infected patients and 70 non-HIV-infected controls paired according sex and age. Automatic (gold standard) and manual measurements of IMC were performed in the carotid arteries. Manual measurements were also performed in common femoral and right subclavian arteries. Bland-Altman graphs were utilized in the comparison and the adopted level significance was 5%. Results Intima-media complex alterations were not observed in any of the individuals as the mean automatic measurement in the right common carotid (RCC) artery was considered as the gold standard. As the gold standard was compared with the manual measurements (mean, maximum and minimum), no clinically significant alteration was observed. As the gold standard was compared with other sites, the difference was statistically and clinically significant at the origin of right subclavian artery (RCC: 0.51 mm vs. 0.91 mm) (p < 0.001). Conclusion HIV-infected individuals are not at higher risk for atherosclerosis than the control population.

Prevalence of exclusive lower extremity metastases at 18F-NaF PET/CT

AbstractObjective:To evaluate the prevalence of exclusive lower extremity metastases, specifically in the femur and below the knee, observed at 18F-NaF PET/CT.Materials and Methods:One thousand consecutive PET/CT studies were retrospectively evaluated for the presence of exclusive uptake in lower extremities suggesting metastatic involvement. The presumptive diagnoses based on such uptakes were subsequently obtained by evaluation of other imaging studies.Results:No exclusive uptake suggestive of metastasis below the femur was observed in the present series. Exclusive uptake was observed in the proximal femur with a presumptive diagnosis of metastasis in two patients.Conclusion:The prevalence of exclusive metastasis below the femur is low and scanning from head to knees is appropriate in most cases.

The right dorsolateral prefrontal cortex prevents post-error slowing

Adjusting behavior following the detection of inappropriate actions allows flexible adaptation to task demands and environmental contingencies during goal-directed behaviors. Post-error behavioral adjustments typically consist in adopting more cautious response mode, which manifests as a slowing down of response speed. Although converging evidence involves the dorsolateral prefrontal cortex (DLPFC) in post-error behavioral adjustment, whether and when the left or right DLPFC is critical for post-error slowing (PES), as well as the underlying brain mechanisms, remain highly debated. To resolve these issues, we used single-pulse transcranial magnetic stimulation in healthy human adults to disrupt the left or right DLPFC selectively at various delays within the 30-180ms interval following false alarms commission, while participants preformed a standard visual Go/NoGo task. PES significantly increased after TMS disruption of the right, but not the left DLPFC at 150ms post-FA response. We discuss these results in terms of an involvement of the right DLPFC in reducing the detrimental effects of error detection on subsequent behavioral performance, as opposed to implementing adaptative error-induced slowing down of response speed.

On the interplay between Q^2 and t dependence in exclusive diffractive production of real photons and vector mesons in ep collisions

We show how the familiar phenomenological way of combining the Q2 (photon virtuality) and t (squared momentum transfer) dependences of the scattering amplitude in Deeply Virtual Compton Scattering (DVCS) [1, 2] and Vector Meson Production (VMP) [2] processes can be understood in an off-mass-shell generalization of dual amplitudes with Mandelstam analyticity [3]. By comparing different approaches, we managed also to constrain the numerical values of the free parameters.