Lung retrieval from non–heart beating cadavers with the use of a rat lung transplant model

AbstractBackground: Lungs retrieved from cadavers after death and circulatory arrest may alleviate the critical shortage of lungs for transplant. We report a rat lung transplantation model that allows serial measurement of arterial blood gases after left single lung transplantation from non–heart beating donors. Methods: Twelve Sprague-Dawley rats underwent left lung transplantation with a vascular cuff technique. Donor rats were anesthetized with intraperitoneal injection of pentobarbital, heparinized, intubated via tracheotomy, and then killed with pentobarbital. Lungs were retrieved immediately or after 2 hours of oxygen ventilation after death (tidal volume 1 mL/100 g, rate 40/min FIO2 = 1.0, positive end-expiratory pressure 5 cm H2O). Recipient rats were anesthetized, intubated, and ventilated. The carotid artery and jugular vein were cannulated for arterial blood gases and infusion of Ringer's lactate (4 mL/h). Anesthesia was maintained with halothane 0.2%, and recipient arterial blood gases were measured at 4 and 6 hours after lung transplantation after snaring the right pulmonary artery for 5 minutes. Animals were put to death 6 hours after lung transplantation, and portions of transplanted lungs were frozen in liquid nitrogen and assayed for wet/dry ratio, myeloperoxidase as a measure of neutrophil infiltration, and conjugated dienes as a measure of free radical–mediated lipid peroxidation. Results: Arterial PO2 and wet/dry ratio were not significantly different in recipients of non–heart beating donor lungs retrieved immediately after death or after 2 hours of oxygen ventilation. Significant neutrophil infiltration was observed in recipients of non–heart beating donor lungs retrieved 2 hours after death from oxygenventilated donors. Conclusions: Strategies to ameliorate reperfusion injury may allow for successful lung transplantation from non–heart beating donors.J Thorac Cardiovasc Surg 2001;122:18-2

Lung retrieval from non–heart beating cadavers with the use of a rat lung transplant model

AbstractBackground: Lungs retrieved from cadavers after death and circulatory arrest may alleviate the critical shortage of lungs for transplant. We report a rat lung transplantation model that allows serial measurement of arterial blood gases after left single lung transplantation from non–heart beating donors. Methods: Twelve Sprague-Dawley rats underwent left lung transplantation with a vascular cuff technique. Donor rats were anesthetized with intraperitoneal injection of pentobarbital, heparinized, intubated via tracheotomy, and then killed with pentobarbital. Lungs were retrieved immediately or after 2 hours of oxygen ventilation after death (tidal volume 1 mL/100 g, rate 40/min FIO2 = 1.0, positive end-expiratory pressure 5 cm H2O). Recipient rats were anesthetized, intubated, and ventilated. The carotid artery and jugular vein were cannulated for arterial blood gases and infusion of Ringer's lactate (4 mL/h). Anesthesia was maintained with halothane 0.2%, and recipient arterial blood gases were measured at 4 and 6 hours after lung transplantation after snaring the right pulmonary artery for 5 minutes. Animals were put to death 6 hours after lung transplantation, and portions of transplanted lungs were frozen in liquid nitrogen and assayed for wet/dry ratio, myeloperoxidase as a measure of neutrophil infiltration, and conjugated dienes as a measure of free radical–mediated lipid peroxidation. Results: Arterial PO2 and wet/dry ratio were not significantly different in recipients of non–heart beating donor lungs retrieved immediately after death or after 2 hours of oxygen ventilation. Significant neutrophil infiltration was observed in recipients of non–heart beating donor lungs retrieved 2 hours after death from oxygenventilated donors. Conclusions: Strategies to ameliorate reperfusion injury may allow for successful lung transplantation from non–heart beating donors.J Thorac Cardiovasc Surg 2001;122:18-2

Challenges and Outcomes of Posterior Wall Isolation for Ablation of Atrial Fibrillation

BACKGROUND: The left atrial posterior wall (PW) often contains sites required for maintenance of atrial fibrillation (AF). Electrical isolation of the PW is an important feature of all open surgeries for AF. This study assessed the ability of current ablation techniques to achieve PW isolation (PWI) and its effect on recurrent AF. METHODS AND RESULTS: Fifty-seven consecutive patients with persistent or high-burden paroxysmal AF underwent catheter ablation, which was performed using an endocardial-only (30) or a hybrid endocardial-epicardial procedure (27). The catheter ablation lesion set included pulmonary vein antral isolation and a box lesion on the PW (roof and posterior lines). Success in creating the box lesion was assessed as electrical silence of the PW (voltage <0.1 mV) and exit block in the PW with electrical capture. Cox proportional hazards models were used for analysis of AF recurrence. PWI was achieved in 21 patients (36.8%), more often in patients undergoing hybrid ablation than endocardial ablation alone (51.9% versus 23.3%, P=0.05). Twelve patients underwent redo ablation. Five of 12 had a successful procedural PWI, but all had PW reconnection at the redo procedure. Over a median follow-up of 302 days, 56.1% of the patients were free of atrial arrhythmias. No parameter including procedural PWI was a statistically significant predictor of recurrent atrial arrhythmias. CONCLUSIONS: PWI during catheter ablation for AF is difficult to achieve, especially with endocardial ablation alone. Procedural achievement of PWI in this group of patients was not associated with a reduction in recurrent atrial arrhythmias, but reconnection of the PW was common

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Suprasternal direct aortic approach transcatheter aortic valve replacement avoids sternotomy and thoracotomy: first-in-man experience

Direct aortic deployment of a transcatheter aortic valve eliminates the need to traverse the aortic arch with the valve delivery system, enables placement of large sheaths in the aorta and innominate artery, provides maximal precision during deployment and ensures a safe, conventional surgical aortotomy closure. We describe the initial experience with the Suprasternal Aortic Access System (SuprAA System, Aegis Surgical Ltd, Dublin, Ireland) for direct transaortic/innominate valve delivery. Patients with severe, symptomatic aortic stenosis who were candidates for transcatheter aortic valve replacement (TAVR) via a direct transaortic approach were enrolled in the SuprAA-TAVR First-in-Man Study. Under general anaesthesia, the innominate artery and aortic arch were exposed in each patient, using the SuprAA System via a 2.5-cm incision directly above the sternal notch. The TAVR delivery sheath was positioned and the transcatheter valve deployed routinely under fluoroscopic guidance. Upon sheath removal, haemostasis at the aortotomy site was confidently secured using a double purse-string suture closure. All were extubated immediately. A meta-analysis of the direct aortic approach was done for comparison. Four male patients (mean 82.5 years) underwent SuprAA-TAVR (2 CoreValve; 2 SAPIEN). Anatomical visualization was excellent and suprasternal valve deployment was accurate regardless of sheath size with 100% Valve Academic Research Consortium-2 procedural success. The average total procedure time was 109.5 min without perioperative wound or vascular complications. The SuprAA System provides direct aortic/innominate access without sternal or thoracotomy incision. Patient recovery to normal activity is maximized, sheath size limitations are eliminated and valve deployment is precise. This innovative system creates a new and exciting minimally invasive approach for high-risk patients with aortic stenosis

Challenges and Outcomes of Posterior Wall Isolation for Ablation of Atrial Fibrillation

BACKGROUND: The left atrial posterior wall (PW) often contains sites required for maintenance of atrial fibrillation (AF). Electrical isolation of the PW is an important feature of all open surgeries for AF. This study assessed the ability of current ablation techniques to achieve PW isolation (PWI) and its effect on recurrent AF. METHODS AND RESULTS: Fifty‐seven consecutive patients with persistent or high‐burden paroxysmal AF underwent catheter ablation, which was performed using an endocardial‐only (30) or a hybrid endocardial–epicardial procedure (27). The catheter ablation lesion set included pulmonary vein antral isolation and a box lesion on the PW (roof and posterior lines). Success in creating the box lesion was assessed as electrical silence of the PW (voltage <0.1 mV) and exit block in the PW with electrical capture. Cox proportional hazards models were used for analysis of AF recurrence. PWI was achieved in 21 patients (36.8%), more often in patients undergoing hybrid ablation than endocardial ablation alone (51.9% versus 23.3%, P=0.05). Twelve patients underwent redo ablation. Five of 12 had a successful procedural PWI, but all had PW reconnection at the redo procedure. Over a median follow‐up of 302 days, 56.1% of the patients were free of atrial arrhythmias. No parameter including procedural PWI was a statistically significant predictor of recurrent atrial arrhythmias. CONCLUSIONS: PWI during catheter ablation for AF is difficult to achieve, especially with endocardial ablation alone. Procedural achievement of PWI in this group of patients was not associated with a reduction in recurrent atrial arrhythmias, but reconnection of the PW was common