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Journal of Cardiothoracic and Vascular... Apr 2023The remedē System (ZOLL Medical, Minnetonka, MN; Fig 1), which was approved by the Food and Drug Administration in October of 2017, is a transvenous device that... (Review)
Review
The remedē System (ZOLL Medical, Minnetonka, MN; Fig 1), which was approved by the Food and Drug Administration in October of 2017, is a transvenous device that stimulates the phrenic nerve for the treatment of central sleep apnea, which is often associated with heart failure and atrial fibrillation. Given the similarity in implantation procedure to pacemakers and implantable cardioverter/defibrillators, the remedē System implantation often occurs in the electrophysiology laboratory. Despite the transvenous nature and close proximity to cardiac structures on radiographic imaging, the remedē System does not have any cardiac pacing function/antiarrhythmia therapies, and it is important for an anesthesiologist to be able to recognize and manage such a device if they were to come across one preoperatively.
Topics: Humans; Treatment Outcome; Phrenic Nerve; Defibrillators, Implantable; Thoracic Surgical Procedures; Sleep Apnea, Central
PubMed: 36732130
DOI: 10.1053/j.jvca.2023.01.011 -
Journal of Neurophysiology Jan 2023Phrenic motoneurons (PhrMNs) innervate diaphragm myofibers. Located in the ventral gray matter (lamina IX), PhrMNs form a column extending from approximately the third... (Review)
Review
Phrenic motoneurons (PhrMNs) innervate diaphragm myofibers. Located in the ventral gray matter (lamina IX), PhrMNs form a column extending from approximately the third to sixth cervical spinal segment. Phrenic motor output and diaphragm activation are impaired in many neuromuscular diseases, and targeted delivery of drugs and/or genetic material to PhrMNs may have therapeutic application. Studies of phrenic motor control and/or neuroplasticity mechanisms also typically require targeting of PhrMNs with drugs, viral vectors, or tracers. The location of the phrenic motoneuron pool, however, poses a challenge. Selective PhrMN targeting is possible with molecules that move retrogradely upon uptake into phrenic axons subsequent to diaphragm or phrenic nerve delivery. However, nonspecific approaches that use intrathecal or intravenous delivery have considerably advanced the understanding of PhrMN control. New opportunities for targeted PhrMN gene expression may be possible with intersectional genetic methods. This article provides an overview of methods for targeting the phrenic motoneuron pool for studies of PhrMNs in health and disease.
Topics: Rats; Animals; Rats, Sprague-Dawley; Motor Neurons; Gene Transfer Techniques; Diaphragm; Phrenic Nerve
PubMed: 36416447
DOI: 10.1152/jn.00432.2022 -
Sleep Medicine Reviews Oct 2023
Topics: Humans; Phrenic Nerve; Sleep Apnea, Central; Treatment Outcome; Polysomnography
PubMed: 37778155
DOI: 10.1016/j.smrv.2023.101841 -
Operative Neurosurgery (Hagerstown, Md.) Nov 2023Nerve sheath tumors of the brachial plexus frequently distort the local anatomy, increasing the difficulty of safe exposure and resection. However, lateral displacement...
BACKGROUND AND OBJECTIVES
Nerve sheath tumors of the brachial plexus frequently distort the local anatomy, increasing the difficulty of safe exposure and resection. However, lateral displacement of the phrenic nerve has not been previously described. The purpose of this study was thus to illustrate the abnormal lateral displacement of the phrenic nerve in 2 cases of patients undergoing brachial plexus tumor resection and provide a possible mechanism for this observation.
METHODS
Two patients underwent surgical resection of clinically progressing C5 schwannomas. During exposure, the phrenic nerve was found to be significantly more superficial and lateral than typical. This structural relationship persisted even after complete resection of the lesion. Both patients did well postoperatively.
RESULTS
The phrenic nerve traverses along the anterolateral aspect of the anterior scalene. However, in these 2 cases of C5 nerve sheath tumors, the phrenic was found to be significantly more lateral and superficial than usual, draping across the medial aspect of the tumor. We believe that the C5-phrenic communicating branch may act as a functional tether that mobilizes the phrenic nerve laterally as the tumor grows. The mass effect on the anterior scalene by the underlying C5 tumor may further contribute to the anterolateral and superficial displacement of the nerve.
CONCLUSION
The phrenic nerve may be seen markedly more laterally and superficially displaced in cases of C5 nerve sheath tumors. It is important for surgeons who operate on lesions of the brachial plexus to be aware of this phenomenon.
Topics: Humans; Phrenic Nerve; Brachial Plexus; Brachial Plexus Neuropathies; Nerve Sheath Neoplasms; Neurilemmoma
PubMed: 37707421
DOI: 10.1227/ons.0000000000000854 -
The Annals of Thoracic Surgery Jun 2020
Topics: Fontan Procedure; Humans; Peripheral Nervous System Diseases; Phrenic Nerve
PubMed: 31765619
DOI: 10.1016/j.athoracsur.2019.09.094 -
Muscle & Nerve Mar 2021Unilateral diaphragmatic paralysis (UDP) has major clinical and etiological implications and, therefore, is important to diagnose. Lung function tests and invasive...
BACKGROUND
Unilateral diaphragmatic paralysis (UDP) has major clinical and etiological implications and, therefore, is important to diagnose. Lung function tests and invasive transdiaphragmatic pressure (Pdi) measurements are widely used to this end but, contrary to phrenic nerve conduction study (NCS), they require volitional maneuvers and/or may be poorly tolerated by patients. The purpose of this study was to compare the diagnostic accuracy of Pdi and phrenic NCS for UDP.
METHODS
We retrospectively reviewed 28 patients with suspected UDP. The diagnosis established during a multidisciplinary meeting was the reference standard.
RESULTS
Phrenic NCS correlated well with Pdi (r = 0.82, P < .005), and the two tests showed good agreement (κ = 0.82, P < .005). Phrenic NCS and Pdi measurements both had 95% sensitivity, 87.5% specificity, 95% positive predictive, and 87.5% negative predictive values.
CONCLUSIONS
Both tests were highly sensitive and specific. Phrenic NCS measurement is a simple, reproducible, noninvasive method whose results correlate well with Pdi and provide insight into the UDP mechanism. In the most difficult cases, combining lung function tests, respiratory muscle assessments, and phrenic NCS can help to establish the diagnosis.
Topics: Adult; Aged; Electrodiagnosis; Esophagus; Female; Humans; Male; Middle Aged; Neural Conduction; Phrenic Nerve; Predictive Value of Tests; Pressure; Respiratory Function Tests; Respiratory Muscles; Respiratory Paralysis; Retrospective Studies; Sensitivity and Specificity; Stomach; Transducers, Pressure
PubMed: 33314195
DOI: 10.1002/mus.27144 -
Neurology India 2022To report a new patient friendly and convenient technique for phrenic nerve conduction with alternative sites of stimulation and recording.
OBJECTIVE
To report a new patient friendly and convenient technique for phrenic nerve conduction with alternative sites of stimulation and recording.
METHODS
Phrenic nerve conduction was performed in forty volunteers and ten patients of peripheral neuropathy. Active recording electrode was placed in tenth intercostal space 2.5 cm away from para-spinal muscles (mid-scapular line), reference electrode in eighth intercostal space just medial to subcostal margin with ground between stimulating and recording electrode. Stimulation was done at the level of crico-thyroid space near or under the posterior margin of sternocleidomastoid muscle. This new method was compared with existing ones.
ANALYSIS
Data was analysed using SPSS 23 version. Correlation between height, weight, body mass index, age, and chest expansion was done using bi-variate correlation. Mean latency and amplitude of the study method were compared with other methods using MANNOVA test.
RESULTS
Total of forty subjects were studied. Thirty-seven were male subjects. Mean age was 28.03 ± 9.63 years, height 168.0 ± 9.60 cm and chest expansion 3.53 ± 0.64 cm. Right sided phrenic nerve mean latency was 5.99 ± 0.629 ms and amplitude 1.088 ± 0.178 mV. Left sided phrenic nerve conductions showed mean latency of 6.02 ± 1.82 ms, amplitude of 1.092 ± 0.2912 mV. These standard deviations were smaller than what were observed with other methods suggesting increased consistency of our results. There was no correlation between phrenic nerve conduction with age, height, gender or chest expansion.
CONCLUSION
This study method gave a better as well as consistent morphology, higher amplitude and required lower amount of current strength. It was superior to previously reported methods in consistency of normative data.
Topics: Adolescent; Adult; Female; Humans; Male; Young Adult; Action Potentials; Back; Electrodes; Electromyography; Neck; Neural Conduction; Neurologic Examination; Peripheral Nervous System Diseases; Phrenic Nerve
PubMed: 36412357
DOI: 10.4103/0028-3886.360904 -
Journal of the Peripheral Nervous... Sep 2019Diaphragm weakness in Charcot-Marie-Tooth disease 1A (CMT1A) is usually associated with severe disease manifestation. This study comprehensively investigated phrenic...
Diaphragm weakness in Charcot-Marie-Tooth disease 1A (CMT1A) is usually associated with severe disease manifestation. This study comprehensively investigated phrenic nerve conductivity, inspiratory and expiratory muscle function in ambulatory CMT1A patients. Nineteen adults with CMT1A (13 females, 47 ± 12 years) underwent spiromanometry, diaphragm ultrasound, and magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots, with recording of diaphragm compound muscle action potentials (dCMAP, n = 15), transdiaphragmatic and gastric pressures (twPdi and twPgas, n = 12). Diaphragm motor evoked potentials (dMEP, n = 15) were recorded following cortical magnetic stimulation. Patients had not been selected for respiratory complaints. Disease severity was assessed using the CMT Neuropathy Scale version 2 (CMT-NSv2). Healthy control subjects were matched for age, sex, and body mass index. The following parameters were significantly lower in CMT1A patients than in controls (all P < .05): forced vital capacity (91 ± 16 vs 110 ± 15% predicted), maximum inspiratory pressure (68 ± 22 vs 88 ± 29 cmH O), maximum expiratory pressure (91 ± 23 vs 123 ± 24 cmH O), and peak cough flow (377 ± 135 vs 492 ± 130 L/min). In CMT1A patients, dMEP and dCMAP were delayed. Patients vs controls showed lower diaphragm excursion (5 ± 2 vs 8 ± 2 cm), diaphragm thickening ratio (DTR, 1.9 [1.6-2.2] vs 2.5 [2.1-3.1]), and twPdi (8 ± 6 vs 19 ± 7 cmH O; all P < .05). DTR inversely correlated with the CMT-NSv2 score (r = -.59, P = .02). There was no group difference in twPgas following abdominal muscle stimulation. Ambulatory CMT1A patients may show phrenic nerve involvement and reduced respiratory muscle strength. Respiratory muscle weakness can be attributed to diaphragm dysfunction alone. It relates to neurological impairment and likely reflects a disease continuum.
Topics: Adult; Charcot-Marie-Tooth Disease; Diaphragm; Electric Stimulation; Female; Humans; Male; Middle Aged; Muscle Weakness; Phrenic Nerve; Respiratory Muscles; Ultrasonography
PubMed: 31393643
DOI: 10.1111/jns.12341 -
Arquivos de Neuro-psiquiatria Dec 2017The aim of the present study was to define normative data of phrenic nerve conduction parameters of a healthy population.
OBJECTIVE
The aim of the present study was to define normative data of phrenic nerve conduction parameters of a healthy population.
METHODS
Phrenic nerve conduction studies were performed in 27 healthy volunteers.
RESULTS
The normative limits for expiratory phrenic nerve compound muscle action potential were: amplitude (0.47 mv - 0.83 mv), latency (5.74 ms - 7.10 ms), area (6.20 ms/mv - 7.20 ms/mv) and duration (18.30 ms - 20.96 ms). Inspiratory normative limits were: amplitude (0.67 mv - 1.11 mv), latency (5.90 ms - 6.34 ms), area (5.62 ms/mv - 6.72 ms/mv) and duration (13.77 ms - 15.37 ms).
CONCLUSION
The best point of phrenic nerve stimulus in the neck varies among individuals between the medial and lateral border of the clavicular head of the sternocleidomastoid muscle and stimulation of both sites, then choosing the best phrenic nerve response, seems to be the appropriate procedure.
Topics: Action Potentials; Adult; Electric Stimulation; Electromyography; Female; Healthy Volunteers; Humans; Male; Middle Aged; Neural Conduction; Neurologic Examination; Phrenic Nerve; Reaction Time; Young Adult
PubMed: 29236890
DOI: 10.1590/0004-282X20170153 -
The American Journal of Cardiology Oct 2022RespiCardia remedē System (Minnetonka, MN 2017), a transvenous phrenic nerve stimulator, is indicated to treat central sleep apnea (CSA) by stimulating the phrenic...
RespiCardia remedē System (Minnetonka, MN 2017), a transvenous phrenic nerve stimulator, is indicated to treat central sleep apnea (CSA) by stimulating the phrenic nerve to cause diaphragmatic contraction to restore normal breathing during sleep. CSA is associated with decreased patient quality of life and worsens cardiovascular outcomes. Systematic review was conducted according to the Preferred Reporting of Systematic Reviews and Meta-Analysis guidelines. PubMed/MEDLINE, Cochrane, EBSCO CINAHL, and Ovid databases were queried by 2 independent reviewers for English-language studies published between 2000 and 2021. The initial search screened for all occurrences of "remedē" then was further refined to include studies evaluating use of the RespiCardia remedē System as a treatment for CSA in multiple patients. A total of 124 articles were identified from the initial search results. A total of 37 articles were identified through screening of title and abstracts from initial results. Full-text review of all the articles was then completed. Of the 13 articles included, a total of 232 patients underwent device implantation. We sought to summarize the available evidence regarding patient selection for implantation, immediate and delayed complications, adherence to therapy, and polysomnographic evidence of efficacy. All 13 articles detailed significant decreases in central apnea index and many patients reported significant mild to marked improvement in quality of life. In conclusion, the remedē System has been demonstrated to improve sleep and respiratory parameters, with few complications. This device demonstrates safe and effective treatment of moderate to severe CSA in adult patients, including those with heart failure.
Topics: Adult; Electric Stimulation Therapy; Humans; Phrenic Nerve; Quality of Life; Sleep Apnea, Central; Systematic Reviews as Topic
PubMed: 35918232
DOI: 10.1016/j.amjcard.2022.06.038