Mapping the collateral network: Optimal near-infrared spectroscopy optode placement.

BACKGROUND: Paraplegia after extensive aortic procedures is a disastrous complication, and maintenance of adequate spinal cord perfusion/oxygenation is pivotal to its prevention. Collateral network (CN) near-infrared spectroscopy (cnNIRS) has been introduced as a noninvasive method for indirect spinal cord oxygenation monitoring. However, the CN has not been investigated in its entirety using this monitoring modality. This study aimed to identify the optimal cnNIRS positioning in an acute large animal model for routine clinical use. METHODS: The paraspinous CN was measured from the high thoracic region to the low lumbar region (T4-L5) using cnNIRS in 10 juvenile pigs (plus reference data from 7 animals) during aortic ischemia and reperfusion. These data were compared with data on direct regional tissue perfusion of the CN and the spinal cord. RESULTS: After aortic cross-clamping, cnNIRS at the mid-thoracic to the low lumbar level decreased rapidly to a nadir at 10 minutes of distal ischemia (mean difference, 18.3 ± 11% to 44.5 ± 9%; P < .001 to .045), with more pronounced changes in the caudal regions. High thoracic cnNIRS remained stable (mean difference, 4.3 ± 4%; P = .915). Measurements of cnNIRS, CN, and spinal cord regional perfusion demonstrated comparable curve progressions starting from the mid-thoracic region (r = 0.5-0.7; P < .001). CONCLUSIONS: cnNIRS is capable of detecting relevant changes during ischemia and reperfusion from the mid-thoracic level downward with characteristic oxygenation patterns corresponding to CN and spinal cord regional perfusion. For extensive aortic procedures, noninvasive cnNIRS placement appears to be useful from the mid-thoracic level (T7-T9) to the lower lumbar level (L3-L5) and also may serve as a versatile monitoring method for procedures limited to the proximal thoracic aorta.

Near real-time bedside detection of spinal cord ischaemia during aortic repair by microdialysis of the cerebrospinal fluid.

OBJECTIVES: Spinal cord ischaemia (SCI) remains the most devastating complication after thoraco-abdominal aortic aneurysm (TAAA) repair. Its early detection is crucial if therapeutic interventions are to be successful. Cerebrospinal fluid (CSF) is readily available and accessible to microdialysis (MD) capable of detecting metabolites involved in SCI [i.e. lactate, pyruvate, the lactate/pyruvate ratio (LPR), glucose and glycerol] in real time. Our aim was to evaluate the feasibility of CSF MD for the real-time detection of SCI metabolites. METHODS: In a combined experimental and translational approach, CSF MD was evaluated (i) in an established experimental large animal model of SCI with 2 arms: (a) after aortic cross-clamping (AXC, N = 4), simulating open TAAA repair and (b) after total segmental artery sacrifice (Th4-L5, N = 8) simulating thoracic endovascular aortic repair. The CSF was analysed utilizing MD every 15 min. Additionally, CSF was collected hourly from 6 patients undergoing open TAAA repair in a high-volume aortic reference centre and analysed using CSF MD. RESULTS: In the experimental AXC group, CSF lactate increased 3-fold after 10 min and 10-fold after 60 min of SCI. Analogously, the LPR increased 5-fold by the end of the main AXC period. Average glucose levels demonstrated a 1.5-fold increase at the end of the first (preconditioning) AXC period (0.60±0.14 vs 0.97±0.32 mmol/l); however, they decreased below (to 1/3 of) baseline levels (0.60±0.14 vs 0.19±0.13 mmol/l) by the end of the experiment (after simulated distal arrest). In the experimental segmental artery sacrifice group, lactate levels doubled and the LPR increased 3.3-fold within 30 min and continued to increase steadily almost 5-fold 180 min after total segmental artery sacrifice (P < 0.05). In patients undergoing TAAA repair, lactate similarly increased 5-fold during ischaemia, reaching a maximum at 6 h postoperatively. In 2 patients with intraoperative SCI, indicated by a decrease in the motor evoked potential of >50%, the LPR increased by 200%. CONCLUSIONS: CSF is widely available during and after TAAA repair, and CSF MD is feasible for detection of early anaerobic metabolites of SCI. CSF MD is a promising new tool combining bedside availability and real-time capacity to potentially enable rapid detection of imminent SCI, thereby maximizing chances to prevent permanent paraplegia in patients with TAAA.

Optimal occlusion pattern for minimally invasive staged segmental artery coil embolization in a chronic porcine model.

OBJECTIVES: Minimally invasive staged segmental artery coil- and plug embolization (MIS2ACE) has been introduced for spinal cord injury prevention prior to open or endovascular thoraco-abdominal aortic aneurysm repair. To date, no optimal pattern has been developed. The aim of this study was to identify the optimal MIS2ACE occlusion pattern. METHODS: Twenty-five juvenile pigs were randomly assigned to 3 MIS2ACE occlusion patterns (2 stages) and a control group [single-stage segmental artery (SA) occlusion, N = 7]. The first pattern started with occlusion of all lumbar segmental arteries in the first stage and the remaining thoracic arteries in the second stage (regional pattern, N = 6). In group 2, an alternating approach with occlusion of every other SA in the first stage and the remainder in the second stage was used (alternating pattern, N = 6). The third pattern started with occluding the watershed area between thoracic level 12 and lumbar level 2 in the first stage and the remaining arteries in the second stage (watershed pattern, N = 6). Neurological assessment at 6-h intervals and spinal cord tissue perfusion measurements via microspheres at 6 time points were performed. At the end of the experiments, the spinal cord was histopathologically examined. RESULTS: An average of 6 ± 2 coils were used per SA. In the control group a total of 57% (N = 4) of animals experienced permanent paraplegia, 1 animal (16%) of the alternating and watershed intervention group suffered from permanent paraplegia. Animals from the staged regional pattern did not experience permanent paraplegia. Furthermore, no evidence of significant tissue damage was observed (P < 0.05 vs control). Tissue perfusion of the lumbar spinal cord in the regional pattern group recovered within 3 days after the second stage to 89.2 ± 47 percent-of-baseline (P = 0.393), whereas mean perfusion of the other 2 intervention groups and the control remained significantly lower compared to the baseline (35.7 ± 16%, 30.2 ± 11% and 63.2 ± 19, P < 0.05). CONCLUSIONS: This study provides evidence that MIS2ACE (minimally invasive staging) may result in less ischaemic spinal cord injury and favourable neurological outcomes compared to complete (1 stage) SA occlusion. A regional-based occlusion pattern (starting with the lumbar segmental arteries) seems to be the best 2-stage approach.

Rapid pannus formation after few months of obstructing aortic mechanical prosthesis.

We report a rare case of a prosthetic aortic valve obstruction due to pannus formation only 3 months following aortic and mitral valve replacement. Fragments of asymmetrical pannus formation affected one of the leaflets of the bi-leaflet mechanical valve; the leaflet appeared immobile due to pannus ingrowth into the mechanical skeleton resulting in encroachment of the leaflet, which in turn became immobile. The patient successfully underwent emergency redo-aortic valve replacement.

Eosinophilic gastroenteritis--a diagnostic enigma.

Eosinophilic gastroenteritis is a heterogeneous and curable disease of the gastrointestinal tract. The diagnosis is rare, with an approximate incidence of 1/100,000. The pathophysiology is based on infiltration of the eosinophils involving various parts of gastrointestinal system, but also different layers of the wall. The authors present a case of the eosinophilic gastroenteritis, which is characterised by the predominant subserosal type associated with asthma, ascites and bilateral pleural effusion. In patients with asthma and abdominal symptomatology, eosinophilic gastroenteritis should be considered as a possible diagnosis. These two atopic conditions may occur more frequently than generally expected, especially in the presence of protein-losing gastroenteropathy. ▸ Consider a diagnosis of eosinophilic gastroenteritis in patients with atopy and gastrointestinal symptoms. ▸ Histological demonstration of the gastrointestinal tract and/or ascites. ▸ Exclude other causes of eosinophilia such as parasites, Churg-Strauss syndrome, hypereosinophilic syndrome.