Emergence of Modular Structure in a Large-Scale Brain Network with Interactions between Dynamics and Connectivity

A network of 32 or 64 connected neural masses, each representing a large population of interacting excitatory and inhibitory neurons and generating an electroencephalography/magnetoencephalography like output signal, was used to demonstrate how an interaction between dynamics and connectivity might explain the emergence of complex network features, in particular modularity. Network evolution was modeled by two processes: (i) synchronization dependent plasticity (SDP) and (ii) growth dependent plasticity (GDP). In the case of SDP, connections between neural masses were strengthened when they were strongly synchronized, and were weakened when they were not. GDP was modeled as a homeostatic process with random, distance dependent outgrowth of new connections between neural masses. GDP alone resulted in stable networks with distance dependent connection strengths, typical small-world features, but no degree correlations and only weak modularity. SDP applied to random networks induced clustering, but no clear modules. Stronger modularity evolved only through an interaction of SDP and GDP, with the number and size of the modules depending on the relative strength of both processes, as well as on the size of the network. Lesioning part of the network, after a stable state was achieved, resulted in a temporary disruption of the network structure. The model gives a possible scenario to explain how modularity can arise in developing brain networks, and makes predictions about the time course of network changes during development and following acute lesions

Redo renal denervation using a multi-electrode radiofrequency system in patients with persistent therapy-resistant hypertension

Objectives Renal sympathetic denervation has been studied as a potential therapeutic option for patients with therapyresistant hypertension; however, a significant proportion of patients do not show a significant reduction in blood pressure and are classified as non-responders. The objective of the present study was to assess whether a redo renal denervation procedure increases response rates. Methods We present a case series of three consecutive renal denervation non-responders treated with the multi-electrode radiofrequency St. Jude EnligHTN catheter after an average of 22 months. Patients were followed for 6 months. Results Mean age was 66 years and two patients were male. Patients were previously treated using either ReCor’s Paradise system, the Vessix V2 system or the Covidien OneShot system. Mean office blood pressure one year after the initial procedure was 187/102mmHg with a mean 24 h ambulatory blood pressure of 166/102mmHg. All patients underwent a successful redo procedure using the EnligHTN system because of persistent therapy-resistant hypertension. At 6 months a significant drop in both office and ambulatory blood pressure of -27/-6mmHg and -15/-13mmHg, respectively, was observed. No significant renal artery stenosis was observed at 6 months. Conclusions In patients with therapy-resistan

Pre-procedural planning of transcatheter mitral valve replacement in mitral stenosis with multi-detector tomography-derived 3D modeling and printing: A case report

Background: Transcatheter mitral valve replacement (TMVR) may be a valuable treatment option for mitral annular calcification and severe mitral stenosis (MS) in patients at high operative risk. Pre-procedural virtual and printed simulations may aid in procedure planning, device sizing, and mitigate complications such as valve embolization or left ventricular outflow tract (LVOT) obstruction. Case summary: We describe a case of TMVR in which multi-detector computed tomography (MDCT) derived, three-dimensional virtual planning and a 3D-printed model of the patients' left heart provided enhanced understanding of an individual patient's unique anatomy to determine feasibility, device sizing, and risk stratification. This resulted in deployment of an adequately sized valve. Post-TMVR LVOT obstruction was treated with LVOT balloon dilatation and percutaneous transluminal septal myocardial ablation. Discussion: Advanced MDCT-derived planning techniques introduce consistent 3D modeling and printing to enhance understanding of intracardiac anatomical relationships and test device implantation. Still, static measurements do not feature haemodynamic factors, tissue, or device characteristics and do not predict device host interaction. Transcatheter mitral valve replacement is feasible in MS when adequately pre-procedurally planned. Multi-detector computed tomography-derived, 3D, virtual and printed models contribute to adequate planning in terms of determining patient eligibility, procedure feasibility, and device sizing. However, static 3D modeling cannot completely eliminate the risk of peri-procedural complications

The effect of transcatheter aortic valve implantation on pulmonary artery pressures in a patient suffering from chronic heart failure:A case report

BACKGROUND: Pulmonary hypertension (PH) is most commonly caused by left-sided heart disease and may negatively affect the long-term prognosis and quality of life of patients with chronic heart failure (CHF). CardioMEMS (Micro-Electro-Mechanical-System) allows physicians to monitor pulmonary artery (PA) pressures remotely and optimize heart failure treatment based on haemodynamic parameters, which provides further insight into the effect of valvular interventions. CASE SUMMARY: We present a case of a 61-year-old male patient with an ischaemic cardiomyopathy, poor LV function, moderate to severe mitral regurgitation, and severe aortic valve regurgitation in refractory heart failure. Right heart catheterization and CardioMEMS monitoring revealed severe pulmonary hypertension with mean PA pressures of 55 mmHg and a mean pulmonary capillary wedge pressure of 21 mmHg despite up titration of heart failure medication and sildenafil. Pulmonary and systemic causes of pulmonary hypertension were excluded. After heart team consensus, the patient underwent transcatheter aortic valve implantation (TAVI) which resulted in normalization of PA pressures and a significant improvement of functional performance. DISCUSSION: To the best of our knowledge, this is the first case report describing the direct effects of TAVI on continuous PA pressures in a patient with poor LV function and severe aortic regurgitation. Elective TAVI appeared to be safe and very effective in reverting severe pulmonary hypertension. Most strikingly, drug interventions could not affect the elevated pulmonary pressures, but TAVI corrected the aortic valve insufficiency with normalization of left-sided pulmonary hypertension

SARS-CoV2 (COVID-19) infection: is fetal surgery in times of national disasters reasonable?

Even though the global COVID‐19 pandemic may affect how medical care is delivered in general, most countries try to maintain steady access for women to routine pregnancy care, including fetal anomaly screening. This means that, also during this pandemic, fetal anomalies will be detected, and that discussions regarding invasive genetic testing and possibly fetal therapy will need to take place. For patients, concerns about Severe Acute Respiratory Syndrome‐Corona Virus 2 will add to the anxiety caused by the diagnosis of a serious fetal anomaly. Yet, also for fetal medicine teams the situation gets more complex as they must weigh up the risks and benefits to the fetus as well as the mother, while managing a changing evidence base and logistic challenges in their healthcare system

Effect of catheter-based renal denervation on left ventricular function, mass and (un)twist with two-dimensional speckle tracking echocardiography

Background: Speckle tracking echocardiography (STE) is an echocardiography modality that is able to measure left ventricular (LV) characteristics, including rotation, strain and strain rate. Strain measures myocardial fibre contraction and relaxation. This study aims to assess the effect of renal sympathetic denervation (RDN) on functional myocardial parameters, including STE, and to identify potential differences between responders and non-responders. Methods: The study population consisted of 31 consecutive patients undergoing RDN in the context of treatment for resistant hypertension. Patients were included between December 2012 and June 2014. Transthoracic echocardiography and speckle tracking analysis was performed at baseline and at 6 months follow-up. Results: The study population consisted of 31 patients with treatment-resistant hypertension treated with RDN (mean age 64 ± 10 years, 15 men). The total study population could be divided into responders (n = 19) and non-responders (n = 12) following RDN. RDN reduced office blood pressure by 18.9 ± 26.8/8.5 ± 13.5 mmHg (p < 0.001). A significant decrease was seen in LV posterior wall thickness (LVPWd) (0.47 ± 1.0 mm; p = 0.020), without a significant change in the LV mass index (LVMI). In the total cohort, only peak late diastolic filling velocity (A-wave velocity) decreased significantly by 5.3 ± 13.2 cm/s (p = 0.044) and peak untwisting velocity decreased significantly by 14.5 ± 28.9°/s (p = 0.025). Conclusion: RDN reduced blood pressure and significantly improved functional myocardial parameters such as A-wave velocity and peak untwisting velocity in patients with treatment-resistant hypertension, suggesting a potential beneficial effect of RDN on myocardial mechanics