Musculoskeletal ultrasonography combined with electromyography in the diagnosis of massage-inducted lateral plantar nerve injury: A case report.

INTRODUCTION: It is well known that foot massage is a very prevalent stress relief method in China. Literatures have reported various massage-inducted peripheral nerve injuries. However, massage-inducted lateral plantar nerve (LPN) injury is very rare. Here, we represent an unusual case of massage-inducted LPN damage, and we also report the diagnostic method of this patient using musculoskeletal ultrasonography combined with electromyography (EMG). PATIENT CONCERNS: A 21-year-old woman presented symptoms of redness, swelling, pain and numbness in the medial right ankle joint for 2 days. DIAGNOSIS: The results of musculoskeletal ultrasonography and EMG provide great help for doctors to make accurate diagnosis. The patient was eventually diagnosed with LPN injury. INTERVENTIONS: No further foot massage was allowed. Vitamin B12 was taken orally for 2 months. Conservative therapy, including electrical stimulation therapy and infrared therapy, was conducted. Besides, active rehabilitation training was also performed. OUTCOMES: The discomfort symptoms were relieved significantly after 2 months conservative treatment. Clinical symptoms and EMG examination illustrated satisfactory result during follow up time. CONCLUSION: The report showed that the masseur should be very careful when doing foot massage to prevent nerve damage. Besides, musculoskeletal ultrasonography combined with EMG can provide important evidence for accurate and effective diagnosis of LPN injury.

Daño neurológico perioperatorio. Identificación de factores de riesgo, prevención y estudios relacionados / Perioperative nerve injury. Risk factor identification, prevention and work-up

BACKGROUND: Regional anesthesia techniques can have adverse effects, like peripheral nerve injuries. This can affect the practitioner on the choice of techniques when offering multimodal analgesia. CASE REPORT: We present the case of an arthroscopic rotator cuff repair on a patient with no comorbidities who presented peripheral nerve injury during post-op. Initially thought to have occurred as a consequence of the anesthetic technique, further study of the patient revealed the injuries to have been produced by the arthroscopic surgery. CONCLUSION: There are multiple factors that influence the possibility of peripheral nerve injury associated with nerve blocks. They can be grouped as related to the patient, the anesthetic technique or the surgical technique, the latter being the most relevant. If a patient manifests signs of peripheral nerve injury high-resolution magnetic resonance of the neural tissue must be performed immediately. Sensory nerve conduction study and electromyography must be performed 4 weeks after by an expert neurologist.

INTRODUCCIÓN: La anestesia regional puede producir como efecto adverso lesiones de nervios periféricos, lo que puede hacer desistir al anestesiólogo de realizar técnicas que mejoran la analgesia multimodal. CASO CLÍNICO: Se presenta el caso de un paciente sin comorbilidades que se operó de reparación artroscópica del manguito rotador y presentó daño neurológico postoperatorio. Inicialmente se sospechó que el daño había sido producido durante la técnica anestésica, sin embargo, el estudio adecuado demostró que el daño se relacionaba con la técnica quirúrgica. CONCLUSIÓN: Existen factores que influyen en la posibilidad de daño neurológico asociado a bloqueos de nervios periféricos que pueden ser propios del paciente, de la técnica anestésica o quirúrgicos, siendo estos últimos los más relevantes. En un paciente con clínica compatible debe realizarse resonancia magnética del tejido neural de alta resolución de forma inmediata; estudio de conducción neural sensitiva y electromiografía a las 4 semanas de evolución por un neurólogo experto.

Clinical feasibility of pulmonary vein orifice pacing for the prediction of phrenic nerve injury during cryoballoon ablation of atrial fibrillation.

INTRODUCTION: Phrenic nerve (PN) injury is a well-known complication of cryoballoon ablation (CBA) for pulmonary vein (PV) isolation in patients with atrial fibrillation. However, it is still insufficient to practically predict phrenic nerve injury (PNI) before freezing. We hypothesized that phrenic nerve capture (PNC) with phrenic nerve orifice pacing (PVOP) might be a surrogate sign of the close proximity of the PN, and that might predict PNI and changes in the compound motor action potential (CMAP) amplitude. METHODS: Seventy patients (60 ± 12 years, male 80%, paroxysmal 56%) underwent PVOP with a 20-electrode ring catheter before the CBA. The clinical outcome was the occurrence of transient and persistent PNI. In addition, the PV position and pacing threshold during PNC with PVOP, and changes in the CMAP amplitude were recorded. We compared these measurements between patients with and without PNC (PNC/non-PNC group) with PVOP. RESULTS: PNC with PVOP occurred in 39 (56%) patients and was localized only to the right superior PV. Transient PNI occurred in seven (10%) patients and permanent in none. The CMAP amplitude decreased significantly more in the PNC group (PNC 33% vs non-PNC 16%, P = .027). PNC group had a higher risk of the composite outcome of transient PNI or ≥30% decrease in the CMAP amplitude (PNC 54% vs non-PNC 13%; P < .001). CONCLUSIONS: This PVOP technique could be feasible and contribute to predicting transient PNI and CMAP amplitude reductions before cryoapplications. Further studies are necessary to elucidate the additional efficacy of PVOP over CMAP monitoring alone.

Isolated injury to the tibial division of sciatic nerve after self-massage of the gluteal muscle with massage ball: A case report.

INTRODUCTION: An isolated injury to the tibial division is rare among compressive sciatic neuropathy. To date, isolated injury to the tibial division of the sciatic nerve after self-massage of the gluteal muscle has not been reported. Here, we report a case of compressive sciatic neuropathy diagnosed after self-massage of the gluteal muscle using magnetic resonance image (MRI) and ultrasound images and its associated therapeutic process. PATIENT CONCERNS: A 50-year-old woman presented right lower extremity pain for the past 7 days. DIAGNOSIS: Electrophysiological findings were consistent with right tibial neuropathy proximal to the branch to hamstring muscles. However, T2-weighted MRI showed high signal intensity and swelling in the right sciatic nerves from the superior gemellus level to the quadratus femoris level. After considering both radiologic and electrophysiological findings, the patient was diagnosed with an isolated injury to the tibial division of the right sciatic nerve. INTERVENTIONS: The patient agreed to an ultrasound-guided perineural steroid injection upon receiving detailed explanation of the procedure. OUTCOMES: After the injection, there was significant improvement in pain. CONCLUSION: Therefore, in making a diagnosis of sciatic neuropathy, it may be important to find the lesion via MRI than relying solely on the patient's history or electrophysiologic study.

Polyethylene Glycol: The Future of Posttraumatic Nerve Repair? Systemic Review.

Peripheral nerve injury is a common posttraumatic complication. The precise surgical repair of nerve lesion does not always guarantee satisfactory motor and sensory function recovery. Therefore, enhancement of the regeneration process is a subject of many research strategies. It is believed that polyethylene glycol (PEG) mediates axolemmal fusion, thus enabling the direct restoration of axon continuity. It also inhibits Wallerian degeneration and recovers nerve conduction. This systemic review, performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, describes and summarizes published studies on PEG treatment efficiency in various nerve injury types and repair techniques. Sixteen original experimental studies in animal models and one in humans were analyzed. PEG treatment superiority was reported in almost all experiments (based on favorable electrophysiological, histological, or behavioral results). To date, only one study attempted to transfer the procedure into the clinical phase. However, some technical aspects, e.g., the maximal delay between trauma and successful treatment, await determination. PEG therapy is a promising prospect that may improve the surgical treatment of peripheral nerve injuries in the clinical practice.

Growth factors expression and ultrastructural morphology after application of low-level laser and natural latex protein on a sciatic nerve crush-type injury.

The effects of low-level laser therapy (LLLT) and natural latex protein (F1, Hevea brasiliensis) were evaluated on crush-type injuries (15kg) to the sciatic nerve in the expressions of nerve growth factor (NGF) and vascular endothelium growth factor (VEGF) and ultrastructural morphology to associate with previous morphometric data using the same protocol of injury and treatment. Thirty-six male rats were allocated into six experimental groups (n = 6): 1-Control; 2-Exposed nerve; 3-Injured nerve; 4-LLLT (15J/cm2, 780nm, 30mW, Continuous Wave) treated injured nerve; 5-F1 (0,1mg) treated injured nerve; and 6-LLLT&F1 treated injured nerve. Four or eight weeks after, sciatic nerve samples were processed for analysis. NGF expression were higher (p<0.05) four weeks after in all injured groups in comparison to Control (Med:0.8; Q1:0; Q3:55.5%area). Among them, the Injured (Med:70.7; Q1:64.4; Q3:77.5%area) showed the highest expression, and F1 (Med:17.3; Q1:14.1; Q3:21.7%area) had the lowest. At week 8, NGF expressions decreased in the injured groups. VEGF was expressed in all groups; its higher expression was observed in the injured groups 4 weeks after (Injured. Med:29.5; F1. Med:17.7 and LLLT&F1. Med:19.4%area). At week 8, a general reduction of VEGF expression was noted, remaining higher in F1 (Med:35.1; Q1.30.6; Q3.39.6%area) and LLLT&F1 (Med:18.5; Q1:16; Q3:25%area). Ultrastructural morphology revealed improvements in the treated groups; 4 weeks after, the F1 group presented greater quantity and diameter of the nerve fibers uniformly distributed. Eight weeks after, the F1 and LLLT&F1 showed similar characteristics to the non-injured groups. In summary, these results and our previous studies indicated that F1 and LLLT may favorably influence the healing of nerve crush injury. Four weeks after nerve injury F1 group showed the best results suggesting recovery acceleration; at 8th week F1 and LLLT&F1 groups presented better features and higher vascularization that could be associated with VEGF maintenance.

Betulinic acid, derived from the desert lavender Hyptis emoryi, attenuates paclitaxel-, HIV-, and nerve injury-associated peripheral sensory neuropathy via block of N- and T-type calcium channels.

The Federal Pain Research Strategy recommended development of nonopioid analgesics as a top priority in its strategic plan to address the significant public health crisis and individual burden of chronic pain faced by >100 million Americans. Motivated by this challenge, a natural product extracts library was screened and identified a plant extract that targets activity of voltage-gated calcium channels. This profile is of interest as a potential treatment for neuropathic pain. The active extract derived from the desert lavender plant native to southwestern United States, when subjected to bioassay-guided fractionation, afforded 3 compounds identified as pentacyclic triterpenoids, betulinic acid (BA), oleanolic acid, and ursolic acid. Betulinic acid inhibited depolarization-evoked calcium influx in dorsal root ganglion (DRG) neurons predominantly through targeting low-voltage-gated (Cav3 or T-type) and CaV2.2 (N-type) calcium channels. Voltage-clamp electrophysiology experiments revealed a reduction of Ca, but not Na, currents in sensory neurons after BA exposure. Betulinic acid inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, BA did not engage human mu, delta, or kappa opioid receptors. Intrathecal administration of BA reversed mechanical allodynia in rat models of chemotherapy-induced peripheral neuropathy and HIV-associated peripheral sensory neuropathy as well as a mouse model of partial sciatic nerve ligation without effects on locomotion. The broad-spectrum biological and medicinal properties reported, including anti-HIV and anticancer activities of BA and its derivatives, position this plant-derived small molecule natural product as a potential nonopioid therapy for management of chronic pain.

Conservative treatment after axillary nerve re-injury in a rugby player: a case report.

Axillary nerve injuries are uncommon, although the incidence is higher in athletes, both related to direct contusion or quadrilateral space syndrome. While few studies have investigated conservative strategies that could be proposed to avoid surgery, no previous case report documented the possible role of rehabilitation in axillary nerve reinjuries. Our patient is a 27-year-old male professional rugby player who experienced a recurrent episode of deltoid strength loss, after a previous axillary nerve injury. The MRI of the brachial plexus showed increased signal intensity of C5 spinal root, together with denervation edema in infraspinatus muscle, related to a recent traction injury while the EMG confirmed the persistence of traumatic paresis of axillary nerve and the chronic sufferance of C5 myotome. Our conservative treatment consists in a 2-phases rehabilitation protocol builded up on the basis of a shoulder kinematic test, electrostimulation test and a further EMG. The purpose of this report was to bring attention on axillary nerve conservative management. Premature return to sport may predispose the patient to the risk of re-injury. A prompt diagnosis and a timely specific rehabilitation protocol allow to a safe full-return to professional sport activity and may prevent recurrences.

Updated Retrospective Single-Center Comparative Analysis of Peripheral Nerve Block Complications Using Landmark Peripheral Nerve Stimulation Versus Ultrasound Guidance as a Primary Means of Nerve Localization.

OBJECTIVES: The purpose of this study was to perform an updated analysis of complications associated with upper and lower extremity peripheral nerve blocks (PNBs) performed with ultrasound (US) guidance versus the landmark approach. METHODS: We conducted a single-center retrospective cohort analysis to compare the incidence of PNB complications between the techniques. The primary outcome was local anesthetic systemic toxicity (LAST), whereas the secondary outcomes included short- and long-term nerve injuries. The current query included cases performed between 2012 and 2015. A combined analysis included data extending to 2006. The Statistical examination relied on the χ2 test. RESULTS: During this 4-year period, we performed 7789 US-guided and 498 landmark-guided blocks with no statistically significant difference in the incidence of nerve injury or LAST between the groups. Our 10-year analysis, however, revealed a significant increase (P < .01) in the rate of LAST with the landmark technique: 7 of 5932 versus 0 of 16,858 cases. The combined data also revealed a significant increase (P < .01) in short-term injuries associated with the landmark approach (30 of 5932 versus 33 of 16,858) but no significant difference in the incidence of long-term injuries. CONCLUSIONS: Our analysis supports a conclusion that the use of US guidance during PNBs leads to a significant reduction in the incidence of LAST, adding to growing evidence from similar investigations. The impact of US on the incidence of nerve injuries remains unclear, considering that the nature of transient deficits is thought to be multifactorial, and the frequency of lasting injuries did not differ significantly in this study.

Risk factors for peripheral nerve injuries following neuraxial labour analgesia: a nested case-control study.

BACKGROUND: Post-partum lower extremity motor and sensory dysfunctions occur in 0.1-9.2‰ of deliveries. While macrosomia, lithotomy position and forceps use are well-identified causes of peripheral nerve injuries, additional contributors such as patient condition and anaesthesia care may also have to be considered. METHODS: We performed a case-control study nested in a cohort of 19,840 patients having neuraxial anaesthesia for childbirth. Cases were all patients who developed motor or sensory dysfunction of lower extremities in the post-partum period. These were compared, using Chi-square, Fisher's exact test, logistic regression and time series, to a random sample of controls without any neurological symptoms or injury. RESULTS: We identified 19 (0.96‰) patients with peripheral nerve injuries of which 15 (0.76‰) were likely associated with obstetrical care. In four additional cases (0.20‰), a nerve root injury due to the Tuohy needle was suspected. Univariate risk factors were: a gestational age ≥ 41 weeks, Odds Ratio (OR) 3.8; 95% CI: 1.1-13.1, late initiation of neuraxial anaesthesia OR 8.2; 95% CI: 1.8-37.9, a repeated anaesthetic procedure OR 2.8; 95% CI: 1.0-7.8, assisted delivery with forceps OR 9.8; 95% CI: 1.2-114.1 and newborn birth weight > 3.5 kg with an OR 6.8; 95% CI: 2.0-22.5. CONCLUSION: Obstetrical related factors are the most prominent risk associated with peripheral nerve injuries. This study highlights however that patient and anaesthesia-related factors may also contribute to peripheral nerve injuries.

Electrical superior vena cava isolation using a novel pace-and-ablate technique under diaphragmatic electromyography monitoring.

BACKGROUND: Diaphragmatic compound motor action potential (CMAP) amplitude monitoring is a standard technique to anticipate phrenic nerve injury during cryoballoon ablation. OBJECTIVE: The purpose of this study was to evaluate the feasibility of a novel superior vena cava isolation (SVCI) technique using simultaneous pacing and ablation through the tip of a single mapping/ablation catheter. METHODS: Fifty-four patients with atrial fibrillation were included. Radiofrequency energy was delivered point by point uniformly for 20 seconds with a power of 20 W until achieving SVCI. Diaphragmatic CMAPs were obtained from modified surface electrodes by high-output pacing from the mapping/ablation catheter throughout the procedure (pace-and-ablate group). Applications were interrupted if CMAP amplitudes significantly decreased without fluoroscopy. The data were compared with those of the 54 patients undergoing conventional SVCI (conventional group). RESULTS: Successful SVCI procedures were achieved in all with a mean of 10.3 ± 2.9 applications. In total, among 559 ablation sites, CMAPs were recorded at 95 (17.0%) with baseline amplitudes of 0.45 ± 0.23 mV. In 10 patients (18.5%), isolation was achieved without any radiofrequency deliveries at CMAP-recorded sites. Among the 95 applications, 6 (6.3%) were interrupted because of CMAP amplitude reductions. At the remaining 88 sites, 20-second radiofrequency applications were delivered without any amplitude decrease (from 0.45 ± 0.21 to 0.46 ± 0.23 mV; P = .885). Phrenic nerve injury occurred in 1 patient in the pace-and-ablate group, which recovered 3 months later, and in 3 conventional group patients, of whom 1 recovered 1 month later (P = .308). The total procedure time tended to be shorter (14.5 ± 6.3 minutes vs 16.7 ± 9.2 minutes; P = .153) and fluoroscopy time significantly shorter (3.9 ± 3.0 minutes vs 6.7 ± 5.7 minutes, P = .002) in the pace-and-ablate group than in the conventional group. CONCLUSION: A novel and simple pace-and-ablate technique under diaphragmatic electromyography monitoring might be feasible for an electrical SVCI.

The change of HCN1/HCN2 mRNA expression in peripheral nerve after chronic constriction injury induced neuropathy followed by pulsed electromagnetic field therapy.

Neuropathic pain is usually defined as a chronic pain state caused by peripheral or central nerve injury as a result of acute damage or systemic diseases. It remains a difficult disease to treat. Recent studies showed that the frequency of action potentials in nociceptive afferents is affected by the activity of hyperpolarization-activated cyclic nucleotide-gated cation channels (HCN) family. In the current study, we used a neuropathy rat model induced by chronic constriction injury (CCI) of sciatic nerve to evaluate the change of expression of HCN1/HCN2 mRNA in peripheral nerve and spinal cord. Rats were subjected to CCI with or without pulsed electromagnetic field (PEMF) therapy. It was found that CCI induced neural cell degeneration while PEMF promoted nerve regeneration as documented by Nissl staining. CCI shortened the hind paw withdrawal latency (PWL) and hind paw withdrawal threshold (PWT) and PEMF prolonged the PWL and PWT. In addition, CCI lowers the expression of HCN1 and HCN2 mRNA and PEMF cannot restore the expression of HCN1 and HCN2 mRNA. Our results indicated that PEMF can promote nerve regeneration and could be used for the treatment of neuropathic pain.

Pulmonary Vein Isolation for Paroxysmal Atrial Fibrillation Using a Circular Multipolar Ablation Catheter: Safety and Efficacy Using Low-Power Settings.

INTRODUCTION: The circular irrigated decapolar nMARQ ablation catheter designed for treating atrial fibrillation (AF) has recently been recalled following two deaths due to esoatrial fistula. Injury to the esophagus has been previously reported in up to 50% of patients using 20-25 W unipolar radiofrequency (RF) energy. Low power of 15 W has been proposed to prevent this complication, but the efficacy of this strategy to avoid AF recurrence is unknown. METHODS AND RESULTS: Consecutive patients with drug-refractory, symptomatic AF were included. Under electroanatomical navigation, the nMARQ catheter was used to isolate all PVs by applying 15 W of unipolar RF simultaneously from up to 10 poles during 40 seconds. Multiple applications were used for each vein, until isolation was achieved. Follow-up was performed after a 2-month blanking period. A total of 50 patients (37 males, age 58 ± 10 years) were included. All PVs were acutely isolated without requiring touch-up by conventional ablation catheters. Pericardial effusion occurred in two patients, of whom one required periocardiocentesis. Right phrenic nerve palsy occurred in another patient, which partially resolved. There were no cases of esophageal fistula or stroke. After a follow-up of 15 ± 4 months, AF recurred in 27/50 (54%) patients. CONCLUSION: The recurrence rate of AF with 15 W unipolar applications is high. Despite use of low power, complications such as pericardial effusion and phrenic nerve palsy may occur.

Phrenic nerve protection via packing of gauze into the pericardial space during ablation of cristal atrial tachycardia in a child.

The success of catheter ablation of focal atrial tachycardia is limited by possible collateral damage to the phrenic nerve. Protection of the phrenic nerve is required. Here we present a case of a 9-year-old girl having a history of an unsuccessful catheter ablation of a focal atrial tachycardia near the crista terminalis (because of proximity of the phrenic nerve) who underwent a successful ablation by means of a novel technique for phrenic nerve protection: packing of gauze into the pericardial space. This method is a viable approach for patients with a failed endocardial ablation due to the proximity of the phrenic nerve.

The appropriate use of neurostimulation: avoidance and treatment of complications of neurostimulation therapies for the treatment of chronic pain. Neuromodulation Appropriateness Consensus Committee.

INTRODUCTION: The International Neuromodulation Society (INS) has determined that there is a need for guidance regarding safety and risk reduction for implantable neurostimulation devices. The INS convened an international committee of experts in the field to explore the evidence and clinical experience regarding safety, risks, and steps to risk reduction to improve outcomes. METHODS: The Neuromodulation Appropriateness Consensus Committee (NACC) reviewed the world literature in English by searching MEDLINE, PubMed, and Google Scholar to evaluate the evidence for ways to reduce risks of neurostimulation therapies. This evidence, obtained from the relevant literature, and clinical experience obtained from the convened consensus panel were used to make final recommendations on improving safety and reducing risks. RESULTS: The NACC determined that the ability to reduce risk associated with the use of neurostimulation devices is a valuable goal and possible with best practice. The NACC has recommended several practice modifications that will lead to improved care. The NACC also sets out the minimum training standards necessary to become an implanting physician. CONCLUSIONS: The NACC has identified the possibility of improving patient care and safety through practice modification. We recommend that all implanting physicians review this guidance and consider adapting their practice accordingly.

Clinical experience with a novel electromyographic approach to preventing phrenic nerve injury during cryoballoon ablation in atrial fibrillation.

BACKGROUND: Phrenic nerve palsy remains the most frequent complication associated with cryoballoon-based pulmonary vein (PV) isolation. We sought to characterize our experience using a novel monitoring technique for the prevention of phrenic nerve palsy. METHODS AND RESULTS: Two hundred consecutive cryoballoon-based PV isolation procedures between October 2010 and October 2013 were studied. In addition to standard abdominal palpation during right phrenic nerve pacing from the superior vena cava, all patients underwent diaphragmatic electromyographic monitoring using surface electrodes. Cryoablation was terminated on any perceived reduction in diaphragmatic motion or a 30% decrease in the compound motor action potential (CMAP). During right-sided ablation, a ≥30% reduction in CMAP amplitude occurred in 49 patients (24.5%). Diaphragmatic motion decreased in 30 of 49 patients and was preceded by a 30% reduction in CMAP amplitude in all. In 82% of cases, this reduction in CMAP amplitude occurred during right superior PV isolation. The baseline CMAP amplitude was 946.5±609.2 mV and decreased by 13.8±13.8% at the end of application. This decrease was more marked in the 33 PVs with a reduction in diaphragmatic motion than in those without (40.9±15.3% versus 11.3±10.5%; P<0.001). In 3 cases, phrenic nerve palsy persisted beyond the end of the procedure, with all cases recovering within 6 months. Despite the shortened application all veins were isolated. At repeat procedure the right-sided PVs reconnected less frequently than the left-sided PVs in those with phrenic nerve palsy. CONCLUSIONS: Electromyographic phrenic nerve monitoring using the surface CMAP is reliable, easy to perform, and offers an early warning to impending phrenic nerve injury.

Multiple nerve injuries following repair of a distal biceps tendon rupture--case report and review of the literature.

Current repair of a distal biceps tendon rupture has reverted to the single incision technique. Postoperative complications are rare, but the most common are due to neuropraxia. We present the case of patient who sustained multiple nerve injuries following distal biceps repair. This case is presented with a review of the literature.

Phrenic nerve injury: An underrecognized and potentially preventable complication of pulmonary vein isolation using a wide-area circumferential ablation approach.

INTRODUCTION: Phrenic nerve injury (PNI) is a well-known, although uncommon, complication of pulmonary vein isolation (PVI) using radiofrequency energy. Currently, there is no consensus about how to avoid or minimize this injury. The purpose of this study was to determine how often the phrenic nerve, as identified using a high-output pacing, lies along the ablation trajectory of a wide-area circumferential lesion set. We also sought to determine if PVI can be achieved without phrenic nerve injury by modifying the ablation lesion set so as to avoid those areas where phrenic nerve capture (PNC) is observed. METHODS AND RESULTS: We prospectively enrolled 100 consecutive patients (age 61.7 ± 9.2 years old, 75 men) who underwent RF PVI using a wide-area circumferential ablation approach. A high-output (20 mA at 2 milliseconds) endocardial pacing protocol was performed around the right pulmonary veins and the carina where a usual ablation lesion set would be made. A total of 30% of patients had PNC and required modification of ablation lines. In the group of patients with PNC, the carina was the most common site of capture (85%) followed by anterior right superior pulmonary vein (RSPV) (70%) and anterior right inferior pulmonary vein (RIPV) (30%). A total of 25% of PNC group had capture in all 3 (RSPV, RIPV, and carina) regions. There was no difference in the clinical characteristics between the groups with and without PNC. RF PVI caused no PNI in either group. CONCLUSION: High output pacing around the right pulmonary veins and the carina reveals that the phrenic nerve lies along a wide-area circumferential ablation trajectory in 30% of patients. Modification of ablation lines to avoid these sites may prevent phrenic nerve injury during RF PVI.