Double arterial perfusion strategy for extensive thoracic aortic surgery to avoid lower body hypothermic circulatory arrest

OBJECTIVE To analyse our results of using a double arterial perfusion strategy to avoid lower body hypothermic circulatory arrest after extensive thoracic aortic surgery. METHODS We analysed the intra- and perioperative courses of 10 patients (median age 58 years, median logistic EuroSCORE 14.6) who underwent extensive thoracic aortic surgery with a double arterial perfusion strategy. The main goal of double arterial perfusion is to separate myocardial and supra-aortic from systemic perfusion. Aortic repair starts at the most distal level of the descending aorta, followed by reinsertion of the supra-aortic vessels, and ends with completion of the proximal anastomosis or by any kind of root repair as needed. RESULTS Seven of 10 patients had prior surgery of the thoracic aorta. Indications for surgery were post-dissection aneurysm in 4 patients, true aneurysm in 3, anastomotic aneurysms in 2 and Type B aortic dissection with pseudo-coarctation in 1. Surgical access was performed through median sternotomy with left hemi-clamshell extension in all cases. There was no in-hospital mortality, but perioperative neurological symptoms occurred in 2 patients. These 2 patients developed delayed stroke (after awaking) after an initial uneventful clinical course, and in 1 of them, neurological symptoms resolved completely during follow-up. The median follow-up was 7 (±13) months. There was no death and no need for additional redo surgery during this observational period. CONCLUSIONS Extensive surgery of the thoracic aorta using a double arterial perfusion technique in order to avoid lower body hypothermic circulatory arrest is an attractive option. Further refinements of this technique may enable the safe and effective simultaneous multisegmental treatment of thoracic aortic pathology in patients who would otherwise have to undergo a two-step surgical approach.

Secondary arterial hypertension: when, who, and how to screen?

Secondary hypertension refers to arterial hypertension due to an identifiable cause and affects ∼5-10% of the general hypertensive population. Because secondary forms are rare and work up is time-consuming and expensive, only patients with clinical suspicion should be screened. In recent years, some new aspects gained importance regarding this screening. In particular, increasing evidence suggests that 24 h ambulatory blood pressure (BP) monitoring plays a central role in the work up of patients with suspected secondary hypertension. Moreover, obstructive sleep apnoea has been identified as one of the most frequent causes. Finally, the introduction of catheter-based renal denervation for the treatment of patients with resistant hypertension has dramatically increased the interest and the number of patients evaluated for renal artery stenosis. We review the clinical clues of the most common causes of secondary hypertension. Specific recommendations are given as to evaluation and treatment of various forms of secondary hypertension. Despite appropriate therapy or even removal of the secondary cause, BP rarely ever returns to normal with long-term follow-up. Such residue hypertension indicates either that some patients with secondary hypertension also have concomitant essential hypertension or that irreversible vascular remodelling has taken place. Thus, in patients with potentially reversible causes of hypertension, early detection and treatment are important to minimize/prevent irreversible changes in the vasculature and target organs.

First Clinical Experience With Celt ACD(®) : A Femoral Arterial Puncture Closure Device

Introduction This prospective nonrandomized study compared the safety and efficacy of a novel arterial closure device (ACD) in common femoral artery procedures to that of the FDA submitted historical manual pressure control group, who underwent either a diagnostic angiogram (DA) or a percutaneous coronary intervention (PCI) procedure. Methods and Results A total of 55 patients were enrolled in this study of the novel ACD. Of the 55 patients, 39 were enrolled in the DA group and 16 were enrolled in the PCI group. Six patients were excluded. A device was deployed in 49 patients. Time to hemostasis (TTH), time to ambulation (TTA), device function, and device-related vascular complications were measured. In the device group, the TTH for the combined DA and PCI patients was 32 seconds (0.54 ± 0.93 minutes), significantly lower when compared with 16.0 ± 12.2 minutes (P < 0.0001) for the control group. Overall major vascular complication rate did not differ significantly, device group (1/49) and the historical control group (1/217). TTA in the combined PCI and DA device group was 226.4 ± 231.9 at the German site (site ambulation policy). In the Irish site, the average TTA in the PCI group was 187 minutes (n = 8) and 85 minutes (n = 14) in the DA group. Conclusion The Celt ACD® device is safe, effective, and significantly decreases the TTH compared to manual pressure and has a low vascular complications rate. The device may be effective in early ambulation and discharge of patients postcoronary intervention procedures.

Energy harvesting through arterial wall deformation: design considerations for a magneto-hydrodynamic generator

As the complexity of active medical implants increases, the task of embedding a life-long power supply at the time of implantation becomes more challenging. A periodic renewal of the energy source is often required. Human energy harvesting is, therefore, seen as a possible remedy. In this paper, we present a novel idea to harvest energy from the pressure-driven deformation of an artery by the principle of magneto-hydrodynamics. The generator relies on a highly electrically conductive fluid accelerated perpendicularly to a magnetic field by means of an efficient lever arm mechanism. An artery with 10 mm inner diameter is chosen as a potential implantation site and its ability to drive the generator is established. Three analytical models are proposed to investigate the relevant design parameters and to determine the existence of an optimal configuration. The predicted output power reaches 65 μW according to the first two models and 135 μW according to the third model. It is found that the generator, designed as a circular structure encompassing the artery, should not exceed a total volume of 3 cm3.

Energy harvesting through arterial wall deformation: A FEM approach to fluid–structure interactions and magneto-hydrodynamics

Engineers are confronted with the energy demand of active medical implants in patients with increasing life expectancy. Scavenging energy from the patient’s body is envisioned as an alternative to conventional power sources. Joining in this effort towards human-powered implants, we propose an innovative concept that combines the deformation of an artery resulting from the arterial pressure pulse with a transduction mechanism based on magneto-hydrodynamics. To overcome certain limitations of a preliminary analytical study on this topic, we demonstrate here a more accurate model of our generator by implementing a three-dimensional multiphysics finite element method (FEM) simulation combining solid mechanics, fluid mechanics, electric and magnetic fields as well as the corresponding couplings. This simulation is used to optimize the generator with respect to several design parameters. A first validation is obtained by comparing the results of the FEM simulation with those of the analytical approach adopted in our previous study. With an expected overall conversion efficiency of 20% and an average output power of 30 μW, our generator outperforms previous devices based on arterial wall deformation by more than two orders of magnitude. Most importantly, our generator provides sufficient power to supply a cardiac pacemaker.

Re: "The enigma of lesion morphology in peripheral arterial occlusive disease".

no abstract available

Cost-effectiveness analysis of paclitaxel-coated balloons for endovascular therapy of femoropopliteal arterial obstructions.

PURPOSE To explore the cost-effectiveness of using drug-eluting balloon (DEB) angioplasty for the treatment of femoropopliteal arterial lesions, which has been shown to significantly lower the rates of target lesion revascularization (TLR) compared with standard balloon angioplasty (BA). METHODS A simplified decision-analytic model based on TLR rates reported in the literature was applied to baseline and follow-up costs associated with in-hospital patient treatment during 1 year of follow-up. Costs were expressed in Swiss Francs (sFr) and calculated per 100 patients treated. Budgets were analyzed in the context of current SwissDRG reimbursement figures and calculated from two different perspectives: a general budget on total treatment costs (third-party healthcare payer) as well as a budget focusing on the physician/facility provider perspective. RESULTS After 1 year, use of DEB was associated with substantially lower total inpatient treatment costs when compared with BA (sFr 861,916 vs. sFr 951,877) despite the need for a greater investment at baseline related to higher prices for DEBs. In the absence of dedicated reimbursement incentives, however, use of DEB was shown to be the financially less favorable treatment approach from the physician/facility provider perspective (12-month total earnings: sFr 179,238 vs. sFr 333,678). CONCLUSION Use of DEBs may be cost-effective through prevention of TLR at 1 year of follow-up. The introduction of dedicated financial incentives aimed at improving DEB reimbursements may help lower total healthcare costs.

Design and Realization of an Energy Harvester Using Pulsating Arterial Pressure

Most medical implants run on batteries, which require costly and tedious replacement or recharging. It is believed that micro-generators utilizing intracorporeal energy could solve these problems. However, such generators do not, at this time, meet the energy requirements of medical implants.This paper highlights some essential aspects of designing and implementing a power source that scavenges energy from arterial expansion and contraction to operate an implanted medical device. After evaluating various potentially viable transduction mechanisms, the fabricated prototype employs an electromagnetic transduction mechanism. The artery is inserted into a laboratory-fabricated flexible coil which is permitted to freely deform in a magnetic field. This work also investigates the effects of the arterial wall's material properties on energy harvesting potential. For that purpose, two types of arteries (Penrose X-ray tube, which behave elastically, and an artery of a Göttinger minipig, which behaves viscoelastically) were tested. No noticeable difference could be observed between these two cases. For the pig artery, average harvestable power was 42 nW. Moreover, peak power was 2.38 μW. Both values are higher than those of the current state of the art (6 nW/16 nW). A theoretical modelling of the prototype was developed and compared to the experimental results.

Transcatheter renal denervation for the treatment of resistant arterial hypertension: the Swiss expert consensus

Transcatheter (or percutaneous) renal denervation is a novel technique developed for the treatment of resistant hypertension. So far, only one randomised controlled trial has been published, which has shown a reduction of office blood pressure. The Swiss Society of Hypertension, the Swiss Society of Cardiology, The Swiss Society of Angiology and the Swiss Society of Interventional Radiology decided to establish recommendations to practicing physicians and specialists for good clinical practice. The eligibility of patients for transcatheter renal denervation needs (1.) confirmation of truly resistant hypertension, (2.) exclusion of secondary forms of hypertension, (3.) a multidisciplinary decision confirming the eligibility, (4.) facilities that guarantee procedural safety and (5.) a long-term follow-up of the patients, if possible in cooperation with a hypertension specialist. These steps are essential until long-term data on safety and efficacy are available.

The effect of inner speech on arterial CO2 and cerebral hemodynamics and oxygenation: a functional NIRS study

The aim of the present study was (i) to investigate the effect of inner speech on cerebral hemodynamics and oxygenation, and (ii) to analyze if these changes could be the result of alternations of the arterial carbon dioxide pressure (PaCO2). To this end, in seven adult volunteers, we measured changes of cerebral absolute [O2Hb], [HHb], [tHb] concentrations and tissue oxygen saturation (StO2) (over the left and right anterior prefrontal cortex (PFC)), as well as changes in end-tidal CO2 (PETCO2), a reliable and accurate estimate of PaCO2. Each subject performed three different tasks (inner recitation of hexameter (IRH) or prose (IRP) verses) and a control task (mental arithmetic (MA)) on different days according to a randomized crossover design. Statistical analysis was applied to the differences between pre-baseline, two tasks, and four post-baseline periods. The two brain hemispheres and three tasks were tested separately. During the tasks, we found (i) PETCO2 decreased significantly (p < 0.05) during the IRH ( ~ 3 mmHg) and MA ( ~ 0.5 mmHg) task. (ii) [O2Hb] and StO2 decreased significantly during IRH ( ~ 1.5 μM; ~ 2 %), IRP ( ~ 1 μM; ~ 1.5 %), and MA ( ~ 1 μM; ~ 1.5 %) tasks. During the post-baseline period, [O2Hb] and [tHb] of the left PFC decreased significantly after the IRP and MA task ( ~ 1 μM and ~ 2 μM, respectively). In conclusion, the study showed that inner speech affects PaCO2, probably due to changes in respiration. Although a decrease in PaCO2 is causing cerebral vasoconstriction and could potentially explain the decreases of [O2Hb] and StO2 during inner speech, the changes in PaCO2 were significantly different between the three tasks (no change in PaCO2 for MA) but led to very similar changes in [O2Hb] and StO2. Thus, the cerebral changes cannot solely be explained by PaCO2.