A Holographic Augmented Reality Interface for Visualizing of MRI Data and Planning of Neurosurgical Procedures

Journal of Digital Imaging - The recent introduction of wireless head-mounted displays (HMD) promises to enhance 3D image visualization by immersing the user into 3D morphology. This work...     

Numerical and In Vitro Investigation of a Novel Mechanical Circulatory Support Device Installed in the Descending Aorta

Traditional implantation techniques of assist devices from the apex of left ventricle to the ascending or descending aorta are highly invasive and carry substantial complications for end‐stage heart failure patients. This study has shown that the descending aorta can be a promising location to install an implantable mechanical circulatory support with minimally invasive surgery. Herein, the hemodynamic effect of an in‐house prototyped pump implanted in the descending aorta was investigated numerically as well as experimentally. The objective of the experimental study is met by using the in‐house simulator of the cardiovascular loop replicating congestive heart failure conditions. The objective of the numerical study was met by using the modified version of the concentrated lumped parameter model developed by the same team. The results show that the pump placement in the descending aorta can lead to an improvement in pulsatility. The pressure drop, generated at the upstream of the pump, facilitates the cardiac output as a result of after‐load reduction, but at the same time, it induces a slight drop in the carotid as well as the coronary perfusion. The pressure rise, generated at the downstream of the pump, improves the blood perfusion in the renal circulation.     

Solvent-dehydrated fascia lata allograft for covering intraoral defects: our experience

Mucosal defects in the oral cavity as a result of tumors, preprosthetic surgical procedure, or trauma are always a concern for surgeons. The aim of this study is to present our experience and discuss the advantages and problems arising with the use of solvent-dried human fascia lata allografts in oral mucosal defects, thus evaluating its clinical efficacy. Sixteen intraoral lesions were removed from 15 patients. The rehabilitation of the mucosal defects was achieved using solvent-dehydrated human fascia lata allografts. No graft rejection or infections were detected. The material was effective for enhancing the hemostasis, relieving the pain, and inducing rapid epithelization. The final result was excellent, even though in 2 cases complications were experienced. Hence, the use of the material proved to be reliable, practical, and safe.     

In Vitro Comparison of Two Different Mechanical Circulatory Support Devices Installed in Series and in Parallel

This study investigates the novel approach of placing a ventricular assist pump in the descending aorta in series configuration with the heart and compares it with the two traditional approaches of left‐ventricle‐to‐ascending‐aorta (LV‐AA) and left‐ventricle‐to‐descending‐aorta (LV‐DA) placement in parallel with the heart. Experiments were conducted by using the in‐house simulator of the cardiovascular blood‐flow loop (SCVL). The results indicate that the use of the LV‐AA in‐parallel configuration leads to a significant improvement in the systemic and pulmonic flow as the level of continuous flow is increased; however, this approach is considered highly invasive. The use of the LV‐DA in‐parallel configuration leads to an improvement in the systemic and pulmonic flow at lower levels of continuous flow but at higher levels of pump support leads to retrograde flow. In both in‐parallel configurations, increasing the level of pump continuous flow leads to a decrease in pulsatility to a certain extent. The results of placing the pump in the descending aorta in series configuration show that the pressure drop upstream of the pump facilitates cardiac output as a result of afterload reduction. In addition, the pressure rise downstream of the pump may assist with renal perfusion. However, at the same time, the pressure drop generated at the proximal part of the descending aorta induces a slight drop in carotid perfusion, which would be autoregulated by the brain in a native cardiovascular system. The pulse wave analysis shows that placing the pump in the descending aorta leads to improved pulsatility in comparison with the traditional in‐parallel configurations.     

SGLT2 inhibitors and cardioprotection: a matter of debate and multiple hypotheses

Sodium-glucose co-transporter 2 (SGLT2) inhibitors inhibit glucose re-absorption in the proximal renal tubules. Two trials have shown significant reductions of cardiovascular (CV) events with empagliflozin and canagliflozin, which could not be attributed solely to their antidiabetic effects. The aim of the review is the critical presentation of suggested mechanisms/hypotheses for the SGLT2 inhibitors' cardioprotection. The search of the literature revealed many possible cardioprotective mechanisms, because SGLT2 inhibitors (i) increase natriuresis and act as diuretics with unique properties leading to a reduction in preload and myocardial stretch (the diuretic hypothesis); (ii) decrease blood pressure and afterload (the blood pressure lowering hypothesis), (iii) favor the production of ketones, which can act as a ‘superfuel’ in the cardiac and renal tissue (the ‘thrifty substrate’ hypothesis), (iv) improve many metabolic variables (the metabolic effects hypothesis), (v) exert many anti-inflammatory effects (the anti-inflammatory effects hypothesis), (vi) can act through the angiotensin II type II receptors in the context of simultaneous renin-angiotensin-aldosterone-system (RAAS) blockade leading to vasodilation and positive inotropic effects (the RAAS hypothesis), (vii) directly decrease the activity of the upregulated in heart failure Na⁺–H⁺ exchanger in myocardial cells leading to restoration of mitochondrial calcium handling in cardiomyocytes (the sodium hypothesis). Additionally, some SGLT2 inhibitors exhibit also SGLT1 inhibitory action possibly resulting in an attenuation of oxidative stress in ischemic myocardium (the SGLT1 inhibition hypothesis). Thus, many mechanisms have been suggested (and possibly act cumulatively) for the cardioprotective effects of SGLT2 inhibitors.     

Methods of safe laparoscopic cholecystectomy for left-sided (sinistroposition) gallbladder: A report of two cases and a review of safe techniques

INTRODUCTION

Left-sided gallbladder is a rare anatomical variation. Usually it is discovered intra-operatively and is accompanied by anatomic variations that can prove quite challenging during laparoscopy.

PRESENTATION OF CASE

From a total of almost 3000 laparoscopic cholecystectomies performed in our institution, two cases of left sided gallbladder were unexpectantly identified intraoperatively. There were no indications for the ectopy preoperatively. In both cases modifications of the standard laparoscopic technique were mandatory. They were performed safely with no post-operative complications. Modifications consisted of transposition of the subxiphoid entry port and alteration in the direction of traction of the rest of the graspers. A review of the literature for methods of safe laparoscopic cholecystectomy was conducted.

DISCUSSION

The surgeon must be aware of the anatomic variances in the rare occasion of a left sided gallbladder, since preoperative diagnosis is very difficult.

CONCLUSION

Knowledge of potential hazards and modifications of laparoscopic technique is mandatory in order to avoid complications.