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Janet L. Taylor - One of the best experts on this subject based on the ideXlab platform.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:Key points • Maintained firing of fatigue-sensitive small-diameter muscle afferents is reported to reduce voluntary activation of the homonymous (fatigued) muscle. • Our study determined if firing of fatigue-sensitive afferents from elbow extensor muscles reduces voluntary activation and torque of the non-fatigued elbow flexors. • We examined voluntary activation of the elbow flexors by measuring changes in superimposed twitches evoked by magnetic cortical stimulation during maximal voluntary contractions. • Following a fatiguing contraction of elbow extensors, the voluntary drive to unfatigued flexor muscles was reduced with continued activation of small-diameter muscle afferents produced by a Blood Pressure Cuff inflated to maintain muscle ischaemia. • Continued discharge of small-diameter muscle afferents from one muscle can decrease voluntary drive to another muscle in the same limb and can reduce its maximal voluntary torque. Abstract During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2–3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4%versus 67.9 ± 5.2% of initial maximal torque; means ±s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1%versus 1.8 ± 0.2% ongoing MVC, P= 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9%versus 91.4 ± 2.3% of initial maximal torque; P= 0.007), superimposed twitches were larger (2.7 ± 0.7%versus 1.3 ± 0.2% ongoing MVC; P= 0.02) and voluntary activation lower (81.6 ± 8.2%versus 95.5 ± 6.9%; P= 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2-3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4% versus 67.9 ± 5.2% of initial maximal torque; means ± s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1% versus 1.8 ± 0.2% ongoing MVC, P = 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9% versus 91.4 ± 2.3% of initial maximal torque; P = 0.007), superimposed twitches were larger (2.7 ± 0.7% versus 1.3 ± 0.2% ongoing MVC; P = 0.02) and voluntary activation lower (81.6 ± 8.2% versus 95.5 ± 6.9%; P = 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
David S. Kennedy - One of the best experts on this subject based on the ideXlab platform.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:Key points • Maintained firing of fatigue-sensitive small-diameter muscle afferents is reported to reduce voluntary activation of the homonymous (fatigued) muscle. • Our study determined if firing of fatigue-sensitive afferents from elbow extensor muscles reduces voluntary activation and torque of the non-fatigued elbow flexors. • We examined voluntary activation of the elbow flexors by measuring changes in superimposed twitches evoked by magnetic cortical stimulation during maximal voluntary contractions. • Following a fatiguing contraction of elbow extensors, the voluntary drive to unfatigued flexor muscles was reduced with continued activation of small-diameter muscle afferents produced by a Blood Pressure Cuff inflated to maintain muscle ischaemia. • Continued discharge of small-diameter muscle afferents from one muscle can decrease voluntary drive to another muscle in the same limb and can reduce its maximal voluntary torque. Abstract During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2–3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4%versus 67.9 ± 5.2% of initial maximal torque; means ±s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1%versus 1.8 ± 0.2% ongoing MVC, P= 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9%versus 91.4 ± 2.3% of initial maximal torque; P= 0.007), superimposed twitches were larger (2.7 ± 0.7%versus 1.3 ± 0.2% ongoing MVC; P= 0.02) and voluntary activation lower (81.6 ± 8.2%versus 95.5 ± 6.9%; P= 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2-3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4% versus 67.9 ± 5.2% of initial maximal torque; means ± s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1% versus 1.8 ± 0.2% ongoing MVC, P = 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9% versus 91.4 ± 2.3% of initial maximal torque; P = 0.007), superimposed twitches were larger (2.7 ± 0.7% versus 1.3 ± 0.2% ongoing MVC; P = 0.02) and voluntary activation lower (81.6 ± 8.2% versus 95.5 ± 6.9%; P = 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
Simon C. Gandevia - One of the best experts on this subject based on the ideXlab platform.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:Key points • Maintained firing of fatigue-sensitive small-diameter muscle afferents is reported to reduce voluntary activation of the homonymous (fatigued) muscle. • Our study determined if firing of fatigue-sensitive afferents from elbow extensor muscles reduces voluntary activation and torque of the non-fatigued elbow flexors. • We examined voluntary activation of the elbow flexors by measuring changes in superimposed twitches evoked by magnetic cortical stimulation during maximal voluntary contractions. • Following a fatiguing contraction of elbow extensors, the voluntary drive to unfatigued flexor muscles was reduced with continued activation of small-diameter muscle afferents produced by a Blood Pressure Cuff inflated to maintain muscle ischaemia. • Continued discharge of small-diameter muscle afferents from one muscle can decrease voluntary drive to another muscle in the same limb and can reduce its maximal voluntary torque. Abstract During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2–3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4%versus 67.9 ± 5.2% of initial maximal torque; means ±s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1%versus 1.8 ± 0.2% ongoing MVC, P= 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9%versus 91.4 ± 2.3% of initial maximal torque; P= 0.007), superimposed twitches were larger (2.7 ± 0.7%versus 1.3 ± 0.2% ongoing MVC; P= 0.02) and voluntary activation lower (81.6 ± 8.2%versus 95.5 ± 6.9%; P= 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2-3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4% versus 67.9 ± 5.2% of initial maximal torque; means ± s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1% versus 1.8 ± 0.2% ongoing MVC, P = 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9% versus 91.4 ± 2.3% of initial maximal torque; P = 0.007), superimposed twitches were larger (2.7 ± 0.7% versus 1.3 ± 0.2% ongoing MVC; P = 0.02) and voluntary activation lower (81.6 ± 8.2% versus 95.5 ± 6.9%; P = 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
Chris J. Mcneil - One of the best experts on this subject based on the ideXlab platform.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:Key points • Maintained firing of fatigue-sensitive small-diameter muscle afferents is reported to reduce voluntary activation of the homonymous (fatigued) muscle. • Our study determined if firing of fatigue-sensitive afferents from elbow extensor muscles reduces voluntary activation and torque of the non-fatigued elbow flexors. • We examined voluntary activation of the elbow flexors by measuring changes in superimposed twitches evoked by magnetic cortical stimulation during maximal voluntary contractions. • Following a fatiguing contraction of elbow extensors, the voluntary drive to unfatigued flexor muscles was reduced with continued activation of small-diameter muscle afferents produced by a Blood Pressure Cuff inflated to maintain muscle ischaemia. • Continued discharge of small-diameter muscle afferents from one muscle can decrease voluntary drive to another muscle in the same limb and can reduce its maximal voluntary torque. Abstract During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2–3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4%versus 67.9 ± 5.2% of initial maximal torque; means ±s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1%versus 1.8 ± 0.2% ongoing MVC, P= 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9%versus 91.4 ± 2.3% of initial maximal torque; P= 0.007), superimposed twitches were larger (2.7 ± 0.7%versus 1.3 ± 0.2% ongoing MVC; P= 0.02) and voluntary activation lower (81.6 ± 8.2%versus 95.5 ± 6.9%; P= 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
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firing of antagonist small diameter muscle afferents reduces voluntary activation and torque of elbow flexors
The Journal of Physiology, 2013Co-Authors: David S. Kennedy, Chris J. Mcneil, Simon C. Gandevia, Janet L. TaylorAbstract:During muscle fatigue, firing of small-diameter muscle afferents can decrease voluntary activation of the fatigued muscle. However, these afferents may have a more widespread effect on other muscles in the exercising limb. We examined if the firing of fatigue-sensitive afferents from elbow extensor muscles in the same arm reduces torque production and voluntary activation of elbow flexors. In nine subjects we examined voluntary activation of elbow flexors by measuring changes in superimposed twitches evoked by transcranial magnetic stimulation of the motor cortex during brief (2-3 s) maximal voluntary contractions (MVC). Inflation of a Blood Pressure Cuff following a 2-min sustained MVC blocked Blood flow to the fatigued muscle and maintained firing of small-diameter afferents. After a fatiguing elbow flexion contraction, maximal flexion torque was lower (26.0 ± 4.4% versus 67.9 ± 5.2% of initial maximal torque; means ± s.d.; P < 0.001) and superimposed twitches were larger (4.1 ± 1.1% versus 1.8 ± 0.2% ongoing MVC, P = 0.01) with than without ischaemia. After a fatiguing elbow extensor contraction, maximal flexion torque was also reduced (82.2 ± 4.9% versus 91.4 ± 2.3% of initial maximal torque; P = 0.007), superimposed twitches were larger (2.7 ± 0.7% versus 1.3 ± 0.2% ongoing MVC; P = 0.02) and voluntary activation lower (81.6 ± 8.2% versus 95.5 ± 6.9%; P = 0.04) with than without ischaemia. After a fatiguing contraction, voluntary drive to the fatigued muscles is reduced with continued input from small-diameter muscle afferents. Furthermore, fatigue of the elbow extensor muscles decreases voluntary drive to unfatigued elbow flexors of the same arm. Therefore, firing of small-diameter muscle afferents from one muscle can affect voluntary activation and hence torque generation of another muscle in the same limb.
Wenqi Huang - One of the best experts on this subject based on the ideXlab platform.
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limb remote ischemic preconditioning attenuates lung injury after pulmonary resection under propofol remifentanil anesthesia a randomized controlled study
Anesthesiology, 2014Co-Authors: Cai Li, Miao Xu, Yan Wu, Yunsheng Li, Wenqi HuangAbstract:BACKGROUND: Remote ischemic preconditioning (RIPC) may confer the protection in critical organs. The authors hypothesized that limb RIPC would reduce lung injury in patients undergoing pulmonary resection. METHODS: In a randomized, prospective, parallel, controlled trial, 216 patients undergoing elective thoracic pulmonary resection under one-lung ventilation with propofol-remifentanil anesthesia were randomized 1:1 to receive either limb RIPC or conventional lung resection (control). Three cycles of 5-min ischemia/5-min reperfusion induced by a Blood Pressure Cuff served as RIPC stimulus. The primary outcome was PaO2/FIO2. Secondary outcomes included other pulmonary variables, the incidence of in-hospital complications, markers of oxidative stress, and inflammatory response. RESULTS: Limb RIPC significantly increased PaO2/FIO2 compared with control at 30 and 60 min after one-lung ventilation, 30 min after re-expansion, and 6 h after operation (238 ± 52 vs. 192 ± 67, P = 0.03; 223 ± 66 vs. 184 ± 64, P = 0.01; 385 ± 61 vs. 320 ± 79, P = 0.003; 388 ± 52 vs. 317 ± 46, P = 0.001, respectively). In comparison with control, it also significantly reduced serum levels of interleukin-6 and tumor necrosis factor-α at 6, 12, 24, and 48 h after operation and malondialdehyde levels at 60 min after one-lung ventilation and 30 min after re-expansion (all P < 0.01). The incidence of acute lung injury and the length of postoperative hospital stay were markedly reduced by limb RIPC compared with control (all P < 0.05). CONCLUSION: Limb RIPC attenuates acute lung injury via improving intraoperative pulmonary oxygenation in patients without severe pulmonary disease after lung resection under propofol-remifentanil anesthesia.
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limb remote ischemic preconditioning for intestinal and pulmonary protection during elective open infrarenal abdominal aortic aneurysm repair a randomized controlled trial
Anesthesiology, 2013Co-Authors: Shihong Wen, Xi Yao, Chanyan Huang, Wenqi Huang, Kexuan LiuAbstract:BACKGROUND Remote ischemic preconditioning (RIPC) may confer the cytoprotection in critical organs. The authors hypothesized that limb RIPC would reduce intestinal and pulmonary injury in patients undergoing open infrarenal abdominal aortic aneurysm repair. METHODS In this single-center, prospective, double-blinded, randomized, parallel-controlled trial, 62 patients undergoing elective open infrarenal abdominal aortic aneurysm repair were randomly assigned in a 1:1 ratio by computerized block randomization to receive limb RIPC or conventional abdominal aortic aneurysm repair (control). Three cycles of 5-min ischemia/5-min reperfusion induced by a Blood Pressure Cuff placed on the left upper arm served as RIPC stimulus. The primary endpoint was arterial-alveolar oxygen tension ratio. The secondary endpoints mainly included the intestinal injury markers (serum intestinal fatty acid-binding protein, endotoxin levels, and diamine oxidase activity), the markers of oxidative stress and systemic inflammatory response, and the scores of the severity of intestinal and pulmonary injury. RESULTS In limb RIPC group, a/A ratio was significantly higher than that in control group at 8, 12, and 24 h after cross-clamp release (66 ± 4 vs. 45 ± 4, P = 0.003; 60 ± 6 vs. 37 ± 4, P = 0.002; and 60 ± 5 vs. 47 ± 6, P = 0.039, respectively). All biomarkers reflecting intestinal injury increased over time, and there was significant differences between limb RIPC and control group (P < 0.001). The severity of intestinal and pulmonary injury was decreased by limb RIPC (P = 0.014 and P = 0.001, respectively). CONCLUSIONS Limb RIPC attenuates intestinal and pulmonary injury in patients undergoing elective open infrarenal abdominal aortic aneurysm repair without any potential risk.