Circulating BMP10 Levels Associate With Late Postoperative Atrial Fibrillation and Left Atrial Endomysial Fibrosis.

BACKGROUND: Serum bone morphogenetic protein 10 (BMP10) blood levels are a marker for history of atrial fibrillation (AF) and for major adverse cardiovascular events in patients with AF, including stroke, AF recurrences after catheter ablations, and mortality. The predictive value of BMP10 in patients undergoing cardiac surgery and association with morphologic properties of atrial tissues are unknown. OBJECTIVES: This study sought to study the correlation between BMP10 levels and preoperative clinical traits, occurrence of early and late postoperative atrial fibrillation (POAF), and atrial fibrosis in patients undergoing cardiac surgery. METHODS: Patients with and without preoperative AF history undergoing first cardiac surgery were included (RACE V, n = 147). Preoperative blood biomarkers were analyzed, left (n = 114) and right (n = 125) atrial appendage biopsy specimens were histologically investigated after WGA staining, and postoperative rhythm was monitored continuously with implantable loop recorders (n = 133, 2.5 years). RESULTS: Adjusted multinomial logistic regression indicated that BMP10 accurately reflected a history of persistent AF (OR: 1.24, 95% CI: 1.10-1.40, P = 0.001), similar to NT-pro-BNP. BMP10 levels were associated with increased late POAF90 occurrence after adjustment for age, sex, AF history, and early POAF occurrence (HR: 1.07 [per 0.1 ng/mL increase], 95% CI: 1.00-1.14, P = 0.041). Left atrial endomysial fibrosis (standardized ß = 0.22, P = 0.041) but not overall fibrosis (standardized Β = 0.12, P = 0.261) correlated with circulating BMP10 after adjustment for age, sex, AF history, reduced LVF, and valvular surgery indication. CONCLUSIONS: Increased BMP10 levels were associated with persistent AF history, increased late POAF incidence, and LAA endomysial fibrosis in a diverse sample of patients undergoing cardiac surgery.

Clinical Predictors of Device-Detected Atrial Fibrillation During 2.5 Years After Cardiac Surgery: Prospective RACE V Cohort.

BACKGROUND: Postoperative atrial fibrillation (POAF) is a frequent complication after cardiac surgery that is associated with late atrial fibrillation (AF) recurrences (late-POAF) and increased morbidity and long-term mortality. OBJECTIVES: This study sought to determine device-detected POAF incidence and to identify clinical variables associated with POAF, both in patients with and without preoperative AF history. METHODS: A total of 133 consecutive patients undergoing cardiac surgery were prospectively enrolled and continuously monitored with an implantable loop recorder for 2.5 years after surgery. Preoperative transthoracic echocardiography, 12-lead electrocardiogram, blood biomarkers, and clinical data were analyzed to develop prediction models for early- and late-POAF. RESULTS: In patients without preoperative AF history, early-POAF within the first 90 postoperative days occurred in 41 (47.1%) of 87 patients. Late-POAF after the first 90 postoperative days occurred in 22 (25%) of 87 patients, and 20 of these patients also had early-POAF during the first 90 days (20 of 22 [91%]). Increased right atrial minimum volume indexed for body surface area (RAVImin) and early-POAF were independently associated with late-POAF. A prediction model for late-POAF, which included RAVImin >11 mL/m2, age >65 years, and early-POAF, achieved an area under the curve of 0.82 (95% CI: 0.72-0.92). For patients with preoperative AF-history, late-POAF recurrences were frequent (22 of 33 [67%]). Increased RAVImin was independently associated with a higher incidence of late-POAF. CONCLUSIONS: In patients with and without AF history, late-POAF recurrences are frequent, including in patients undergoing surgical AF ablation. In patients with no history of AF, late-POAF might be predicted with excellent accuracy by using a combination of preoperative variables. In patients with a history of AF, signs of advanced AF substrate (eg, increased right atrial volumes) were associated with long-term AF recurrences. [Reappraisal of Atrial Fibrillation: Interaction Between Hypercoagulability, Electrical Remodeling, and Vascular Destabilisation in the Progression of AF; NCT03124576].

Noninfectious sternal wound inflammation after coronary artery bypass grafting in a patient with myelodysplastic syndrome: A no-touch approach.

Pyoderma gangrenosum (PG) is a rare, chronic inflammatory noninfectious dermatosis. It is associated with underlying systemic or hematological diseases such as myelodysplastic syndrome (MDS) and can be triggered after surgery. Recognition and diagnosis of PG can be difficult as it can mimic a wound infection. Misdiagnosis could lead to invasive procedures which worsen the disease and have possible disastrous aftermath. A 74-year-old male with a history of MDS presents with an atypical sternal wound inflammation. Diagnosis confirmed PG after skin biopsy. No surgical or invasive procedures were performed and the patient was treated on an outpatient basis with prednisolone, clobetasol cream, and cyclosporine. This case shows the importance of a rapid diagnosis of the disease. Awareness is required for the diagnosis of PG in a wound with pronounced livid borders, without improvement after antibiotic treatment or worsening after debridement. Rapid diagnosis and treatment reduce high healthcare costs, morbidity, and mortality.

Evolutionarily conserved transcriptional landscape of the heart defining the chamber specific physiology.

Cardiovascular disease (CVD) remains the leading cause of death worldwide. A deeper characterization of regional transcription patterns within different heart chambers may aid to improve our understanding of the molecular mechanisms involved in myocardial function and further, our ability to develop novel therapeutic strategies. Here, we used RNA sequencing to determine differentially expressed protein coding (PC) and long non-coding (lncRNA) transcripts within the heart chambers across seven vertebrate species and identified evolutionarily conserved chamber specific genes, lncRNAs and pathways. We investigated lncRNA homologs based on sequence, secondary structure, synteny and expressional conservation and found most lncRNAs to be conserved by synteny. Regional co-expression patterns of transcripts are modulated by multiple factors, including genomic overlap, strandedness and transcript biotype. Finally, we provide a community resource designated EvoACTG, which informs researchers on the conserved yet intertwined nature of the coding and non-coding cardiac transcriptome across popular model organisms in CVD research.

Clinical and electrophysiological predictors of device-detected new-onset atrial fibrillation during 3 years after cardiac surgery.

AIMS: Postoperative atrial fibrillation (POAF) after cardiac surgery is an independent predictor of stroke and mortality late after discharge. We aimed to determine the burden and predictors of early (up to 5th postoperative day) and late (after 5th postoperative day) new-onset atrial fibrillation (AF) using implantable loop recorders (ILRs) in patients undergoing open chest cardiac surgery. METHODS AND RESULTS: Seventy-nine patients without a history of AF undergoing cardiac surgery underwent peri-operative high-resolution mapping of electrically induced AF and were followed 36 months after surgery using an ILR (Reveal XT™). Clinical and electrophysiological predictors of late POAF were assessed. POAF occurred in 46 patients (58%), with early POAF detected in 27 (34%) and late POAF in 37 patients (47%). Late POAF episodes were short-lasting (mostly between 2 min and 6 h) and showed a circadian rhythm pattern with a peak of episode initiation during daytime. In POAF patients, electrically induced AF showed more complex propagation patterns than in patients without POAF. Early POAF, right atrial (RA) volume, prolonged PR time, and advanced age were independent predictors of late POAF. CONCLUSIONS: Late POAF occurred in 47% of patients without a history of AF. Patients who develop early POAF, with higher age, larger RA, or prolonged PR time have a higher risk of developing late POAF and may benefit from intensified rhythm follow-up after cardiac surgery. CLINICALTRIALS.GOV NUMBER: NCT01530750.

Role of pre-operative transthoracic echocardiography in predicting post-operative atrial fibrillation after cardiac surgery: a systematic review of the literature and meta-analysis.

AIMS: This systematic review and meta-analysis aims to evaluate the role of pre-operative transthoracic echocardiography in predicting post-operative atrial fibrillation (POAF) after cardiac surgery. METHODS AND RESULTS: Electronic databases were searched for studies reporting on pre-operative echocardiographic predictors of POAF in PubMed, Cochrane library, and Embase. A meta-analysis of echocardiographic predictors of POAF that were identified by at least five different publications was performed. Forty-three publications were included in this systematic review. Echocardiographic predictors for POAF included surrogate parameters for total atrial conduction time (TACT), structural cardiac changes, and functional disturbances. Meta-analysis showed that prolonged pre-operative PA-TDI interval [5 studies, Cohen's d = 1.4, 95% confidence interval (CI) 0.9-1.9], increased left atrial volume indexed for body surface area (LAVI) (23 studies, Cohen's d = 0.8, 95% CI 0.6-1.0), and reduced peak atrial longitudinal strain (PALS) (5 studies, Cohen's d = 1.4, 95% CI 1.0-1.8), were associated with POAF incidence. Left atrial volume indexed for body surface was the most important predicting factor in patients without a history of AF. These parameters remained important predictors of POAF in heterogeneous populations with variable age and comorbidities such as coronary artery disease and valvular disease. CONCLUSION: This meta-analysis shows that increased TACT, increased LAVI, and reduced PALS are valuable parameters for predicting POAF in the early post-operative phase in a large variety of patients.

Veno-Arterial Extracorporeal Life Support in Heart Transplant and Ventricle Assist Device Centres. Meta-analysis.

AIMS: Because reported mortality on veno-arterial (V-A) extracorporeal life support (ECLS) substantially varies between centres, the aim of the current analysis was to assess the outcomes between units performing heart transplantation and/or implanting ventricular assist device (HTx/VAD) vs. non-HTx/VAD units in patients undergoing V-A ECLS for cardiogenic shock. METHODS AND RESULTS: Systematic search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses was performed using PubMed/MEDLINE databases until 30 November 2019. Articles reporting in-hospital/30-day mortality and centre's HTx/VAD status were included. In-hospital outcomes and long-term survival were analysed in subgroup meta-analysis. A total of 174 studies enrolling n = 13 308 patients were included with 20 series performed in non-HTx/VAD centres (1016 patients, 7.8%). Majority of patients underwent V-A ECLS for post-cardiotomy shock (44.2%) and acute myocardial infarction (20.7%). Estimated overall in-hospital mortality was 57.2% (54.9-59.4%). Mortality rates were higher in non-HTx/VAD [65.5% (59.8-70.8%)] as compared with HTx/VAD centres [55.8% (53.3-58.2%)], P < 0.001. Estimated late survival was 61.8% (55.7-67.9%) without differences between non-HTx/VAD and HTx/VAD centres: 66.5% (30.3-1.02%) vs. 61.7% (55.5-67.8%), respectively (P = 0.797). No differences were seen with respect to ECLS duration, limb complications, and reoperations for bleeding, kidney injury, and sepsis. Yet, weaning rates were higher in HTx/VAD vs. non-HTx/VAD centres: 58.7% (56.2-61.1%) vs. 48.9% (42.0-55.9%), P = 0.010. Estimated rate of bridge to heart transplant was 6.6% (5.2-8.3%) with numerical, yet not statistically significant, difference between non-HTx/VAD [2.7% (0.8-8.3%)] as compared with HTx/VAD [6.7% (5.3-8.6%)] (P = 0.131). CONCLUSIONS: Survival after V-A ECLS differed according to centre's HTx/VAD status. Potentially different risk profiles of patients must be taken account for before definite conclusions are drawn.

Pressure and flow properties of dual-lumen cannulae for extracorporeal membrane oxygenation.

INTRODUCTION: In the last decade, dual-lumen cannulae have been increasingly applied in patients undergoing extracorporeal life support. Well-performing vascular access is crucial for efficient extracorporeal membrane oxygenation support; thus, guidance for proper cannulae size is required. Pressure-flow charts provided by manufacturers are often based on tests performed using water, rarely blood. However, blood is a shear-thinning and viscoelastic fluid characterized by different flow properties than water. METHODS: We performed a study evaluating pressure-flow curves during standardized conditions using human whole blood in two commonly available dual-lumen cannulae used in neonates, pediatric, and adult patients. Results were merged and compared with the manufacturer's corresponding curves obtained from the public domain. RESULTS: The results showed that using blood as compared with water predominantly influenced drainage flow. A 10-80% higher pressure-drop was needed to obtain same drainage flow (hematocrit of 26%) compared with manufacturer's water charts in 13-31 Fr bi-caval dual-lumen cannulae. The same net difference was found in cavo-atrial cannulae (16-32 Fr), where a lower drainage pressure was required (Hct of 26%) compared with the manufacturer's test using blood with an Hct of 33%. Return pressure-flow data were similar, independent whether pumping blood or water, to the data reported by manufacturers. CONCLUSION: Non-standardized testing of pressure-flow properties of extracorporeal membrane oxygenation dual-lumen cannulae prevents an adequate prediction of pressure-flow results when these cannulae are used in patients. Properties of dual-lumen cannulae may vary between sizes within same cannula family, in particular concerning the drainage flow.

The impact of Centre's heart transplant status and volume on in-hospital outcomes following extracorporeal membrane oxygenation for refractory post-cardiotomy cardiogenic shock: a meta-analysis.

BACKGROUND: Postcardiotomy cardiogenic shock (PCS) that is refractory to inotropic support remains a major concern in cardiac surgery and is almost universally fatal unless treated with mechanical support. While reported mortality rates on ECMO vary from center to center, aim of the current report is assess if the outcomes differ between centres according to volume and heart transplantation status. METHODS: A systematic search was performed according to PRISMA statement using PubMed/Medline databases between 2010 and 2018. Relevant articles were scrutinized and included in the meta-analysis only if reporting in-hospital/30-day mortality and heart transplantation status of the centre. Paediatric and congenital heart surgery-related studies along with those conducted in the setting of veno-venous ECMO for respiratory distress syndrome were excluded. Differences were assessed by means of subgroup meta-analysis and meta-regression. RESULTS: Fifty-four studies enrolling N = 4421 ECMO patients were included. Of those, 6 series were performed in non-HTx centres (204 pts.;4.6%). Overall 30-day survival (95% Confidence Intervals) was 35.3% (32.5-38.2%) and did not statistically differ between non-HTx: 33.3% (26.8-40.4%) and HTx centres: 35.7% (32.7-38.8%); Pinteraction = 0.531. There was no impact of centre volume on survival as well: ßcoef = 0.0006; P = 0.833. No statistical differences were seen between HTx and non-HTx with respect to ECMO duration, limb complications, reoperations for bleeding, kidney injury and sepsis. There were however significantly less neurological complications in the HTx as compared to non-HTx centres: 11.9% vs 19.5% respectively; P = 0.009; an inverse relationship was seen for neurologic complications in centres performing more ECMOs annually ßcoef = - 0.0066; P = 0.031. Weaning rates and bridging to HTx and/or VADs were higher in HTx facilities. CONCLUSIONS: There was no apparent difference in survival after ECMO implantation for refractory PCS according to centre's ECMO volume and transplantation status. Potentially different risk profiles of patients in these centres must be taken account for before definite conclusions are drawn.

Baseline surgical status and short-term mortality after extracorporeal membrane oxygenation for post-cardiotomy shock: a meta-analysis.

OBJECTIVE: While reported mortality rates on post-cardiotomy extracorporeal membrane oxygenation vary from center to center, impact of baseline surgical status (elective/urgent/emergency/salvage) on mortality is still unknown. METHODS: A systematic search was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement using PubMed/Medline databases until March 2018 using the keywords "postcardiotomy," "cardiogenic shock," "extracorporeal membrane oxygenation," and "extracorporeal life support." Relevant articles were scrutinized and included in the meta-analysis only if reporting in-hospital/30-day mortality and baseline surgical status. The correlations between mortality and percentage of elective/urgent/emergency cases were investigated. Inference analysis of baseline status and extracorporeal membrane oxygenation complications was conducted as well. RESULTS: Twenty-two studies (conducted between 1993 and 2017) enrolling N = 2,235 post-cardiotomy extracorporeal membrane oxygenation patients were found. Patients were mostly of non-emergency status (65.2%). Overall in-hospital/30-day mortality event rate (95% confidence intervals) was 66.7% (63.3-69.9%). There were no differences in in-hospital/30-day mortality with respect to baseline surgical status in the subgroup analysis (test for subgroup differences; p = 0.406). Similarly, no differences between mortality in studies enrolling <50 versus ⩾50% of emergency/salvage cases was found: respective event rates were 66.9% (63.1-70.4%) versus 64.4% (57.3-70.8%); p = 0.525. Yet, there was a significant positive association between increasing percentage of emergency/salvage cases and rates of neurological complications (p < 0.001), limb complications (p < 0.001), and bleeding (p = 0.051). Incidence of brain death (p = 0.099) and sepsis (p = 0.134) was increased as well. CONCLUSION: Other factors than baseline surgical status may, to a higher degree, influence the mortality in patients treated with extracorporeal membrane oxygenation for post-cardiotomy cardiogenic shock. Baseline status, however, strongly influences the complication occurrence while on extracorporeal membrane oxygenation.

Pressure and flow properties of cannulae for extracorporeal membrane oxygenation II: drainage (venous) cannulae.

The use of extracorporeal life support devices such as extracorporeal membrane oxygenation in adults requires cannulation of the patient's vessels with comparatively large diameter cannulae to allow circulation of large volumes of blood (>5 L/min). The cannula diameter and length are the major determinants for extracorporeal membrane oxygenation flow. Manufacturing companies present pressure-flow charts for the cannulae; however, these tests are performed with water. Aims of this study were 1. to investigate the specified pressure-flow charts obtained when using human blood as the circulating medium and 2. to support extracorporeal membrane oxygenation providers with pressure-flow data for correct choice of the cannula to reach an optimal flow with optimal hydrodynamic performance. Eighteen extracorporeal membrane oxygenation drainage cannulae, donated by the manufacturers (n = 6), were studied in a centrifugal pump driven mock loop. Pressure-flow properties and cannula features were described. The results showed that when blood with a hematocrit of 27% was used, the drainage pressure was consistently higher for a given flow (range 10%-350%) than when water was used (data from each respective manufacturer's product information). It is concluded that the information provided by manufacturers in line with regulatory guidelines does not correspond to clinical performance and therefore may not provide the best guidance for clinicians.

Pressure and flow properties of cannulae for extracorporeal membrane oxygenation I: return (arterial) cannulae.

Adequate extracorporeal membrane oxygenation support in the adult requires cannulae permitting blood flows up to 6-8 L/minute. In accordance with Poiseuille's law, flow is proportional to the fourth power of cannula inner diameter and inversely proportional to its length. Poiseuille's law can be applied to obtain the pressure drop of an incompressible, Newtonian fluid (such as water) flowing in a cylindrical tube. However, as blood is a pseudoplastic non-Newtonian fluid, the validity of Poiseuille's law is questionable for prediction of cannula properties in clinical practice. Pressure-flow charts with non-Newtonian fluids, such as blood, are typically not provided by the manufacturers. A standardized laboratory test of return (arterial) cannulae for extracorporeal membrane oxygenation was performed. The aim was to determine pressure-flow data with human whole blood in addition to manufacturers' water tests to facilitate an appropriate choice of cannula for the desired flow range. In total, 14 cannulae from three manufacturers were tested. Data concerning design, characteristics, and performance were graphically presented for each tested cannula. Measured blood flows were in most cases 3-21% lower than those provided by manufacturers. This was most pronounced in the narrow cannulae (15-17 Fr) where the reduction ranged from 27% to 40% at low flows and 5-15% in the upper flow range. These differences were less apparent with increasing cannula diameter. There was a marked disparity between manufacturers. Based on the measured results, testing of cannulae including whole blood flows in a standardized bench test would be recommended.

Long-term survival and major outcomes in post-cardiotomy extracorporeal membrane oxygenation for adult patients in cardiogenic shock.

Extracorporeal membrane oxygenation (ECMO) in the veno-arterial (VA) configuration is an established method for the treatment of refractory cardiogenic shock. Such a condition characterizes the postoperative course of approximatively 1% of cardiac surgery patients. Although some studies have reported ECMO-related short-term results, little is known about the long-term outcomes of VA-ECMO therapy in the post-cardiotomy setting. Therefore, an extensive literature search was conducted regarding articles published after 1990 reporting postoperative ECMO use. PubMed, EMBASE and Web of Science were searched for sources. In-hospital mortality was high in post-cardiotomy VA-ECMO patients, ranging from 24.8% to 52%. Long-term results were poorly reported. However, based on the limited information available, hospital survivors showed a favorable outcome, with improvement in overall clinical condition, quality of life and limited hospital readmission for cardiac-related events. To conclude, in-hospital outcome in post-cardiotomy ECMO is often unfavorable, post-discharge results show satisfactory condition, with stable improvement of overall patient clinical status and low rate of hospital readmission and cardiac-related adverse events. Data reporting is, however, scarce and hence new and detailed studies are still warranted to investigate such aspects.

Protracted aortic valve closure during peripheral veno-arterial extracorporeal life support: is intra-aortic balloon pump an effective solution?

BACKGROUND: Left ventricular (LV) afterload increase with protracted aortic valve (AV) closure may represent a complication of veno-arterial extracorporeal membrane oxygenation (V-A ECMO). The aim of the present study was to assess the effects of an intra-aortic balloon pump (IABP) to overcome such a hemodynamic shortcoming in patients submitted to peripheral V-A ECMO. METHODS: Among 184 adult patients who were treated with peripheral V-A ECMO support at Medical University Center Maastricht Hospital between 2007 and 2018, patients submitted to IABP implant for protracted AV closure after V-A ECMO implant were retrospectively identified. All clinical and hemodynamic data, including echocardiographic monitoring, were collected and analyzed. RESULTS: During the study period, 10 subjects (mean age 60 years old, 80% males) underwent IABP implant after peripheral V-A ECMO positioning due to the diagnosis of protracted AV closure and inefficient LV unloading as assessed by echocardiography and an absence of pulsation in the arterial pressure wave. Recovery of blood pressure pulsatility and enhanced LV unloading were observed in 8 patients after IABP placement, with no significant differences in the main hemodynamic parameters, inotropic therapy or in the ECMO flow (p=0.48). The weaning rate in this patient subgroup (mean ECMO duration 8 days), however, was only 10%, with another patient finally transplanted, leading to a 20% survival-to-hospital discharge. CONCLUSION: IABP placement was an effective solution in order to reverse the protracted AV closure and impaired LV unloading observed during peripheral V-A ECMO support. However, the impact on the weaning rate and survival needs further investigations.

Local Anesthesia for Percutaneous Thoracic Endovascular Aortic Repair.

BACKGROUND: Thoracic endovascular aortic repair (TEVAR) requires large-bore vascular access due to the considerable diameters of the endoprosthesis and delivery device. The preclose technique preceding endograft delivery has opened the door for an evolved access strategy. In addition, treatment under local anesthesia offers the advantage of optimal neuromonitoring. The goal of this study was to analyze the efficacy and safety of percutaneous TEVAR under local anesthesia. METHODS: All patients undergoing TEVAR in an elective setting at the Antwerp University Hospital between June 2012 and June 2015 were prospectively entered into an endovascular database. This database was queried for demographics, procedural details, and access-related complications. All patients underwent a percutaneous approach with the Perclose Proglide under local anesthesia. RESULTS: This review identified 34 patients in whom 37 percutaneous TEVAR procedures were completed under local anesthesia. All patients experienced adequate analgesia, and no conversions to general anesthesia were implemented. The mean size of the arteriotomy was 23.8 ± 1.3 French (F). The number of Proglide deployments was 80, with an 8% rate of failure on deployment. There were no conversions to surgical cutdown, and adequate hemostasis was obtained in all procedures. The incidence of postprocedural access-related complications was 3%. CONCLUSION: Local anesthesia for percutaneous TEVAR can be performed safely and effectively. The percutaneous approach facilitates local anesthesia, which provides the added benefit of early recognition of neurologic complications while maintaining a low risk of access-related complications despite the need for large-bore vascular access.

Laser-Evoked Potentials in Fibromyalgia: The Influence of Greater Occipital Nerve Stimulation on Cerebral Pain Processing.

OBJECTIVE: Fibromyalgia causes widespread musculo-skeletal pain in the four quadrants of the body. Greater occipital nerve stimulation has recently shown beneficial effects in fibromyalgia patients on pain, fatigue, and mood disorders. Laser-evoked potentials (LEPs) are used for research to understand the pathophysiological mechanisms of pain and to evaluate the effects of pain treatment. In fibromyalgia patients, LEPs tend to have a higher N2 amplitude, a tendency to shorter latencies, and patients have a lower pain threshold. Greater occipital nerve stimulation might exert a modulation of the medial pain pathways processing the affective motivational components of pain (unpleasantness) as well as the descending pain inhibitory pathways (reducing pain), both of which are contributing to the N2P2 peak. MATERIALS AND METHODS: To test this hypothesis, the authors performed LEPs in a group of fibromyalgia patients with and without greater occipital nerve stimulation. RESULTS: Occipital nerve stimulation does not alter the amplitudes of the LEP recordings, although a significant difference in latencies can be seen. More specifically, latencies of the N2P2 increased in the condition after stimulation, and especially at the Pz electrode. CONCLUSION: Our results suggest Occipital Nerve Stimulation (ONS) induces a modification of the balance between antinociceptive pain inhibitory pathways and pain-provoking pathways.