539575
research-article2014
VMJ0010.1177/1358863X14539575Vascular MedicineSadiq et al.
Case Report
Median arcuate ligament syndrome: Use of fractional flow reserve in documentation of chronic mesenteric ischemia
Vascular Medicine 2014, Vol. 19(4) 317–321 © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1358863X14539575 vmj.sagepub.com
Immad R Sadiq1,2, Abdulrahman Abdulbaki1,2 and Talhat Azemi1,2
Abstract Median arcuate ligament syndrome (MALS) is a rare clinical entity. This condition typically affects women between the ages of 20 and 40 years and causes symptoms of abdominal pain, primarily post-prandial, as well as nausea, vomiting and weight loss. MALS is considered a diagnosis of exclusion. Typically, mesenteric arterial duplex ultrasonography, computed tomography (CT), and magnetic resonance (MR) are highly suggestive, and conventional contrast angiography confirmatory. We explore the role of fractional flow reserve and intravascular ultrasound in the evaluation of MALS. In order to illustrate the utility of these tools, we present the case of a 47-year-old symptomatic woman who underwent angiography, complemented by assessment of fractional flow reserve and intravascular ultrasound. These data convincingly demonstrated the dynamic nature of the obstructive characteristic of MALS. Keywords hemodynamic processes, mesenteric artery
Introduction Median arcuate ligament syndrome (MALS) or celiac artery compression syndrome (CACS) is an uncommon condition that was first described by Harjola1 in 1963. Two years later, Dunbar and associates published a series that reported successful surgical decompression2 of the celiac artery by division of the median arcuate ligament (MAL). While some controversy exists regarding the causative mechanism of this condition, it is generally believed that MALS is caused by a combination of compression of the celiac ganglion nerve fibers as well as ischemia of the gut serving the celiac artery distribution due to extrinsic compression of the proximal celiac artery by the MAL. By definition, this compression is made worse during expiration and improves with inspiration. MALS is considered a diagnosis of exclusion. This entity is usually diagnosed by excluding other likely conditions that could explain the patient’s symptoms. Imaging in the form of duplex ultrasonography, computed tomography angiography (CTA), magnetic resonance angiography (MRA) and conventional angiography is highly suggestive of proximal celiac artery stenosis in the absence of other lesions. Adjunctive use of intravascular ultrasound (IVUS) in the assessment of MALS has been reported recently as well.3 Most of the diagnostic studies used to evaluate for MALS provide only anatomic information. While the arterial duplex provides physiologic data regarding the degree
of stenosis due to compression of the celiac artery, it has its limitations. An ideal diagnostic modality would provide both objective physiologic data and complementary anatomic detail. We propose the use of fractional flow reserve (FFR) assessment in the evaluation of patients suspected to have MALS as a modality to obtain objective physiologic data. To illustrate the utility of this tool, we report the case of a woman where conventional imaging techniques combined with measurement of FFR and IVUS were used to demonstrate the dynamic nature of compression involving the proximal celiac artery and its resultant physiologic significance.
1Division 2Henry
of Cardiology, Hartford Hospital, Hartford, CT, USA Low Heart Center, Hartford Hospital, Hartford, CT, USA
Corresponding author: Immad R Sadiq 85 Seymour St, Suite #1022 Division of Cardiology Henry Low Heart Center Hartford Hospital Hartford, CT 06106 USA Email: [email protected]
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
318
Vascular Medicine 19(4)
Figure 1. Selective celiac artery angiography. (A) During inspiration. (B) During expiration. The white arrow points to the worsening stenosis of the proximal celiac artery during expiration.
Vignette A 47-year-old Caucasian non-smoking female presented with a 3-year history of epigastric abdominal discomfort associated with nausea and vomiting. She underwent an exhaustive workup for her symptoms including endoscopy, which remained unrevealing. As a final resort, she underwent an MRA that suggested stenosis of the proximal celiac artery. She referred herself to our vascular medicine clinic for further evaluation. Upon interview, she disclosed that initially her symptoms were only post-prandial. Over the past 6 months, she developed constant abdominal pain, which became significantly worse after ingestion of a meal to the extent she had developed true sitophobia. She initially experienced significant weight loss but had gained several pounds over the past 10 months, attributing it to her frequent consumption of high-caloric foods such as ice cream and shakes. On physical exam she was noted to be 5’4”/(163 cm) tall and weighed 137 lb/(62 kg) (BMI 23.5). The exam was unremarkable except for an epigastric bruit that was present during both inspiration and expiration. Given the above findings, MALS was strongly suspected. A duplex ultrasound was performed. Interestingly, this study did not reveal MALS physiology, with a peak systolic velocity (PSV) of 100 cm/s during inspiration and
218 cm/s during expiration. Owing to the high clinical suspicion the patient was taken for contrast angiography. The celiac artery was noted to arise at the level of the L1 vertebral body. A severe stenosis was noted in the proximal celiac artery that was present during inspiration as well as expiration, but clearly more severe during the latter phase of respiration (Figure 1A and B). The superior mesenteric artery (SMA) was noted to be widely patent (Figure 2A and B) with prominent gastro-duodenal collaterals serving the celiac artery (Figure 2C). Selective angiography of the SMA also revealed more robust retrograde filling of the celiac artery during expiration as compared to inspiration. An 0.014” 175 cm pressure wire (PressureWire™; St Jude Medical Inc., St Paul, MN, USA) was then used to interrogate the celiac artery. Measurements were obtained separately during maximal inspiration and expiration, both with and without hyperemia. Hyperemia was induced by intra-arterial administration of 300 μg nitroglycerin. Findings showed significant respiratory variation. Moreover, it was noted that during both phases of respiration, the celiac artery FFR was significantly worse during the hyperemic state. During inspiration the Pd/Pa was 0.94 at baseline and 0.85 with hyperemia (Figure 3A and B). During expiration it was 0.84 at baseline and 0.78 with hyperemia (Figure 3C and D). Anatomic data were also obtained using IVUS (Volcano Corp., San Diego, CA, USA), which demonstrated significant narrowing of the celiac artery proximally (Figure 4). The study showed an abundance of fibrotic tissue in the narrowed segment of the celiac artery. The reference vessel (mid celiac artery) measurements showed a minimal luminal diameter of 8.5 mm, maximal luminal diameter of 10.1 mm and a cross-sectional area of 66.7 mm2. The proximal celiac artery during inspiration showed a minimal luminal diameter of 4.4 mm, maximal luminal diameter of 6.2 mm and a cross-sectional area of 21.6 mm2. This narrowing was noted to worsen upon expiration, showing a minimal luminal diameter of 2.7 mm, maximal luminal diameter of 5.0 mm and a cross-sectional area of 11.9 mm2. IVUS of the SMA did not show any narrowing nor was there any respiratory variation affecting the caliber of this vessel.
Figure 2. (A) Abdominal aortography showing no evidence of aortic or branch atherosclerosis. (B) Lateral aortogram showing severe stenosis of the proximal celiac artery. (C) Selective superior mesenteric artery angiogram shows retrograde filling of the celiac artery via prominent gastro-duodenal collaterals. The white arrow points to the celiac artery.
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
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Sadiq et al.
Figure 3. Celiac artery fractional flow reserve. (A) Inspiration, without hyperemia. (B) Inspiration, with hyperemia. (C) Expiration, without hyperemia. (D) Expiration, with hyperemia. (The red and green waveforms represent the aortic (Pa) and celiac artery pressures (Pd; distal to the stenosis), respectively. The corresponding mean pressures are shown in the sidebar.)
Figure 4. Intravascular ultrasound of the celiac artery. (A) Mid celiac artery, without any narrowing. (B) Proximal celiac artery during inspiration, with significant narrowing. (C) Proximal celiac artery during expiration, with worsening of the baseline (inspiratory) narrowing.
The following day the patient underwent a CTA of her abdomen that clearly demonstrated severe proximal narrowing of the celiac artery with no luminal compromise of the SMA (Figure 5A and B). No evidence of atherosclerotic plaque formation was noted in the abdominal aorta or any of its branches.
Discussion MALS is a rare clinical entity. Its precise etiologic mechanism is not universally accepted but there is compelling evidence linking compression of the celiac artery by the MAL to the symptom complex. Normally, the celiac artery arises from the ventral surface of the aorta between the eleventh thoracic and first lumbar vertebrae.4 Compression of the celiac artery by the MAL is believed to occur when either the celiac artery arises higher than usual or there is a prominent MAL that impinges upon the proximal celiac artery5 despite its normal origin. However, not all cases of compression of the proximal celiac artery lead to MALS. This compression is not a rare occurrence and one study reported subclinical compression of the celiac artery in as many as up to 50% of the subjects studied angiographically, while ischemia provoking compression was believed to occur in only 1%.6
Traditionally, the diagnostic workup for MALS starts with mesenteric arterial duplex ultrasound. This study typically shows increased peak systolic velocities during expiration compared to inspiration, suggesting a more pronounced narrowing of the celiac artery in the former state. However, ultrasound has its limitations such as sonographer experience, patient body habitus and presence of bowel gas that may interfere with adequate image acquisition and thus may not reveal the underlying pathology. While CTA, MRA and conventional angiography are also able to demonstrate a dynamic stenosis in the proximal celiac artery when significant impingement from MAL is present, there is no input from these studies regarding the physiologic significance of such a stenosis. Endovascular treatment as the mainstay of therapy is not beneficial and as such is not advocated. Without relief of the extrinsic compression, stents in the celiac artery remain at risk of repetitive trauma, fragmentation and restenosis.7 Treatment for MALS consists of surgical decompression in the appropriately selected patients. In this procedure the fibers of MAL are divided. Additionally, celiac ganglionectomy is usually performed concomitantly. While open surgery remains the mainstay of therapy, laparoscopic as well as robot-assisted laparoscopic division of MAL has been performed with reasonable
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
320
Vascular Medicine 19(4)
Figure 5. CTA showing severe stenosis in the proximal celiac artery (white arrow) and no obstructive disease in the SMA (gray arrow). (A) Three-dimensional reconstruction image. (B) Sagittal reformatted CT image.
success. However, despite the minimally invasive nature of this procedure, the risk of vascular trauma and conversion to open surgery remains as high as 10–27%.8,9 Combined with celiac artery decompression, revascularization of this vessel either surgically or with angioplasty/ stenting has shown more promise in long-term remission of symptoms. Also, most but not all MALS patients derive significant relief from decompression.10 Therefore, it is incumbent upon the physician to demonstrate not only the presence of a stenosis in the celiac artery in a symptomatic patient but also the association between the detected stenosis and resultant mesenteric ischemia before subjecting the patient to a potentially risky surgery. While conventional imaging modalities used traditionally to make this diagnosis provide adequate anatomic details of the stenosis, they fail to provide any physiologic data. Measurement of a hemodynamically significant gradient across the stenosis would provide such information. While a catheter advanced across a stenosis has been used in the past to measure the gradient, this technique is unreliable and often results in overestimation of the gradient due to the obstruction caused by the catheter itself.11 Using a 0.014” pressure wire employed for measuring FFR offers a valuable alternative. FFR has been used extensively in the assessment of coronary artery disease to determine the physiologic significance of an underlying stenosis.12 This concept has been extrapolated to the non-coronary circulation as well and its use is now being suggested in the evaluation of visceral arterial stenosis.13–16 Our case demonstrates the successful use of a pressure wire in detecting the gradient across the celiac artery stenosis in MALS. In order to mimic the physiologic vasodilatory state that occurs in the post-prandial setting, we induced hyperemia and repeated the FFR. As expected, with hyperemia the gradient across the stenosis increased remarkably. Moreover, and importantly, we were able to show clearly that the gradient, whether baseline or hyperemic, worsened with expiration, thereby strengthening the concept of dynamic extrinsic compression of the celiac artery.
The use of IVUS in our patient not only demonstrated the stenosis but also that it was caused by the small caliber of the vessel rather than luminal narrowing caused by plaque formation. The IVUS findings most likely reflected longstanding extrinsic compression presumably by the median arcuate ligament. The dynamic component of the obstruction – baseline stenosis becoming more severe during expiration – was also obvious with this imaging modality. One other observation from our case is that, based on both FFR and IVUS data, at least in a subset of patients, the compression is present in both phases of respiration. This vignette clearly demonstrates that the celiac artery narrowing in MALS is an anatomical phenomenon with clear physiologic consequences that can explain the symptoms suggestive of chronic mesenteric ischemia. We propose the routine utilization of FFR, a simple but very useful diagnostic modality, in the invasive workup of patients suspected of MALS. This would allow the physicians to not only diagnose the condition with confidence but also to identify and possibly exclude those patients who would not benefit from surgical decompression therapy. We recognize that the ischemic threshold of FFR has not yet been established in mesenteric ischemic disease and, therefore, further studies are warranted. Declaration of conflicting interest The authors declare that there is no conflict of interest.
Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
References 1. Harjola PT. A rare obstruction of the coeliac artery: report of a case. Ann Chir Gynaecol Fenn 1963; 52: 547–550. 2. Dunbar JD, Molnar W, Beman FF, Marable SA. Compression of the celiac trunk and abdominal angina: preliminary report of 15 cases. AJR Am J Roentgenol 1965; 95: 731–744. 3. De Lara FV, Higgins C, Hernandez-Vila EA. Median arcuate ligament syndrome confirmed with the use of intravascular ultrasound. Tex Heart Inst J 2014; 41: 57–60. 4. Watson WC, Sadikali F. Celiac axis compression: experience with 20 patients and a critical appraisal of the syndrome. Ann Intern Med 1977; 86: 278–284. 5. Loukas M, Pinyard J, Vaid S, Kinsella C. Clinical anatomy of celiac artery compression syndrome: a review. Clin Anat 2007; 20: 612–617. 6. Cornell SH. Severe stenosis of the celiac artery. Analysis of patients with and without symptoms. Radiology 1971; 99: 311–316. 7. Delis KT, Gloviczki P, Altuwaijri M, McKusik MA. Median arcuate ligament syndrome: open celiac artery reconstruction and ligament division after endovascular failure. J Vasc Surg 2007; 46: 799–802. 8. Jimenez JC, Harlander-Locke M, Dutson EP. Open and laparoscopic treatment of median arcuate ligament syndrome. Vasc Surg 2012; 56: 869–873. 9. Roseborough GS. Laparoscopic management of celiac artery compression syndrome. J Vasc Surg 2009; 50: 124–133. 10. Jimenez JC, Harlander-Locke M, Dutson EP. Open and laparoscopic treatment of median arcuate ligament syndrome. J Vasc Surg 2012; 56: 869–873. 11. Colyer WR, Cooper CJ, Burket MW, Thomas WJ. Utility of a 0.014” pressure-sensing guidewire to assess renal artery
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
321
Sadiq et al. translesional systolic pressure gradients. Catheter Cardiovasc Interv 2003; 59: 372–377. 12. Tonino PAL, De Bruyne B, Pijls NH, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary angiography. N Engl J Med 2009; 360: 213–224. 13. Hannawi B, Lam WW, Younis GA. Pressure wire used to measure gradient in chronic mesenteric ischemia. Tex Heart Inst J 2012; 39: 739–743. 14. Prasad A, Zafar N, Mahmud E. Assessment of renal artery fibromuscular dysplasia: angiography, intravascular ultrasound
(with virtual histology), and pressure wire measurements. Catheter Cardiovasc Interv 2009; 74: 260–264. 15. De Bruyne B, Manoharan G, Pijls NH, et al. Assessment of renal artery stenosis severity by pressure gradient measurements. J Am Coll Cardiol 2006; 48: 1851–1855. 16. Leesar MA, Varma J, Shapira A, et al. Prediction of hypertension improvement after stenting of renal artery stenosis: comparative accuracy of translesional pressure gradients, intravascular ultrasound and angiography. J Am Coll Cardiol 2009; 25: 2363–2371.
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
research-article2014
VMJ0010.1177/1358863X14539575Vascular MedicineSadiq et al.
Case Report
Median arcuate ligament syndrome: Use of fractional flow reserve in documentation of chronic mesenteric ischemia
Vascular Medicine 2014, Vol. 19(4) 317–321 © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1358863X14539575 vmj.sagepub.com
Immad R Sadiq1,2, Abdulrahman Abdulbaki1,2 and Talhat Azemi1,2
Abstract Median arcuate ligament syndrome (MALS) is a rare clinical entity. This condition typically affects women between the ages of 20 and 40 years and causes symptoms of abdominal pain, primarily post-prandial, as well as nausea, vomiting and weight loss. MALS is considered a diagnosis of exclusion. Typically, mesenteric arterial duplex ultrasonography, computed tomography (CT), and magnetic resonance (MR) are highly suggestive, and conventional contrast angiography confirmatory. We explore the role of fractional flow reserve and intravascular ultrasound in the evaluation of MALS. In order to illustrate the utility of these tools, we present the case of a 47-year-old symptomatic woman who underwent angiography, complemented by assessment of fractional flow reserve and intravascular ultrasound. These data convincingly demonstrated the dynamic nature of the obstructive characteristic of MALS. Keywords hemodynamic processes, mesenteric artery
Introduction Median arcuate ligament syndrome (MALS) or celiac artery compression syndrome (CACS) is an uncommon condition that was first described by Harjola1 in 1963. Two years later, Dunbar and associates published a series that reported successful surgical decompression2 of the celiac artery by division of the median arcuate ligament (MAL). While some controversy exists regarding the causative mechanism of this condition, it is generally believed that MALS is caused by a combination of compression of the celiac ganglion nerve fibers as well as ischemia of the gut serving the celiac artery distribution due to extrinsic compression of the proximal celiac artery by the MAL. By definition, this compression is made worse during expiration and improves with inspiration. MALS is considered a diagnosis of exclusion. This entity is usually diagnosed by excluding other likely conditions that could explain the patient’s symptoms. Imaging in the form of duplex ultrasonography, computed tomography angiography (CTA), magnetic resonance angiography (MRA) and conventional angiography is highly suggestive of proximal celiac artery stenosis in the absence of other lesions. Adjunctive use of intravascular ultrasound (IVUS) in the assessment of MALS has been reported recently as well.3 Most of the diagnostic studies used to evaluate for MALS provide only anatomic information. While the arterial duplex provides physiologic data regarding the degree
of stenosis due to compression of the celiac artery, it has its limitations. An ideal diagnostic modality would provide both objective physiologic data and complementary anatomic detail. We propose the use of fractional flow reserve (FFR) assessment in the evaluation of patients suspected to have MALS as a modality to obtain objective physiologic data. To illustrate the utility of this tool, we report the case of a woman where conventional imaging techniques combined with measurement of FFR and IVUS were used to demonstrate the dynamic nature of compression involving the proximal celiac artery and its resultant physiologic significance.
1Division 2Henry
of Cardiology, Hartford Hospital, Hartford, CT, USA Low Heart Center, Hartford Hospital, Hartford, CT, USA
Corresponding author: Immad R Sadiq 85 Seymour St, Suite #1022 Division of Cardiology Henry Low Heart Center Hartford Hospital Hartford, CT 06106 USA Email: [email protected]
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
318
Vascular Medicine 19(4)
Figure 1. Selective celiac artery angiography. (A) During inspiration. (B) During expiration. The white arrow points to the worsening stenosis of the proximal celiac artery during expiration.
Vignette A 47-year-old Caucasian non-smoking female presented with a 3-year history of epigastric abdominal discomfort associated with nausea and vomiting. She underwent an exhaustive workup for her symptoms including endoscopy, which remained unrevealing. As a final resort, she underwent an MRA that suggested stenosis of the proximal celiac artery. She referred herself to our vascular medicine clinic for further evaluation. Upon interview, she disclosed that initially her symptoms were only post-prandial. Over the past 6 months, she developed constant abdominal pain, which became significantly worse after ingestion of a meal to the extent she had developed true sitophobia. She initially experienced significant weight loss but had gained several pounds over the past 10 months, attributing it to her frequent consumption of high-caloric foods such as ice cream and shakes. On physical exam she was noted to be 5’4”/(163 cm) tall and weighed 137 lb/(62 kg) (BMI 23.5). The exam was unremarkable except for an epigastric bruit that was present during both inspiration and expiration. Given the above findings, MALS was strongly suspected. A duplex ultrasound was performed. Interestingly, this study did not reveal MALS physiology, with a peak systolic velocity (PSV) of 100 cm/s during inspiration and
218 cm/s during expiration. Owing to the high clinical suspicion the patient was taken for contrast angiography. The celiac artery was noted to arise at the level of the L1 vertebral body. A severe stenosis was noted in the proximal celiac artery that was present during inspiration as well as expiration, but clearly more severe during the latter phase of respiration (Figure 1A and B). The superior mesenteric artery (SMA) was noted to be widely patent (Figure 2A and B) with prominent gastro-duodenal collaterals serving the celiac artery (Figure 2C). Selective angiography of the SMA also revealed more robust retrograde filling of the celiac artery during expiration as compared to inspiration. An 0.014” 175 cm pressure wire (PressureWire™; St Jude Medical Inc., St Paul, MN, USA) was then used to interrogate the celiac artery. Measurements were obtained separately during maximal inspiration and expiration, both with and without hyperemia. Hyperemia was induced by intra-arterial administration of 300 μg nitroglycerin. Findings showed significant respiratory variation. Moreover, it was noted that during both phases of respiration, the celiac artery FFR was significantly worse during the hyperemic state. During inspiration the Pd/Pa was 0.94 at baseline and 0.85 with hyperemia (Figure 3A and B). During expiration it was 0.84 at baseline and 0.78 with hyperemia (Figure 3C and D). Anatomic data were also obtained using IVUS (Volcano Corp., San Diego, CA, USA), which demonstrated significant narrowing of the celiac artery proximally (Figure 4). The study showed an abundance of fibrotic tissue in the narrowed segment of the celiac artery. The reference vessel (mid celiac artery) measurements showed a minimal luminal diameter of 8.5 mm, maximal luminal diameter of 10.1 mm and a cross-sectional area of 66.7 mm2. The proximal celiac artery during inspiration showed a minimal luminal diameter of 4.4 mm, maximal luminal diameter of 6.2 mm and a cross-sectional area of 21.6 mm2. This narrowing was noted to worsen upon expiration, showing a minimal luminal diameter of 2.7 mm, maximal luminal diameter of 5.0 mm and a cross-sectional area of 11.9 mm2. IVUS of the SMA did not show any narrowing nor was there any respiratory variation affecting the caliber of this vessel.
Figure 2. (A) Abdominal aortography showing no evidence of aortic or branch atherosclerosis. (B) Lateral aortogram showing severe stenosis of the proximal celiac artery. (C) Selective superior mesenteric artery angiogram shows retrograde filling of the celiac artery via prominent gastro-duodenal collaterals. The white arrow points to the celiac artery.
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
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Sadiq et al.
Figure 3. Celiac artery fractional flow reserve. (A) Inspiration, without hyperemia. (B) Inspiration, with hyperemia. (C) Expiration, without hyperemia. (D) Expiration, with hyperemia. (The red and green waveforms represent the aortic (Pa) and celiac artery pressures (Pd; distal to the stenosis), respectively. The corresponding mean pressures are shown in the sidebar.)
Figure 4. Intravascular ultrasound of the celiac artery. (A) Mid celiac artery, without any narrowing. (B) Proximal celiac artery during inspiration, with significant narrowing. (C) Proximal celiac artery during expiration, with worsening of the baseline (inspiratory) narrowing.
The following day the patient underwent a CTA of her abdomen that clearly demonstrated severe proximal narrowing of the celiac artery with no luminal compromise of the SMA (Figure 5A and B). No evidence of atherosclerotic plaque formation was noted in the abdominal aorta or any of its branches.
Discussion MALS is a rare clinical entity. Its precise etiologic mechanism is not universally accepted but there is compelling evidence linking compression of the celiac artery by the MAL to the symptom complex. Normally, the celiac artery arises from the ventral surface of the aorta between the eleventh thoracic and first lumbar vertebrae.4 Compression of the celiac artery by the MAL is believed to occur when either the celiac artery arises higher than usual or there is a prominent MAL that impinges upon the proximal celiac artery5 despite its normal origin. However, not all cases of compression of the proximal celiac artery lead to MALS. This compression is not a rare occurrence and one study reported subclinical compression of the celiac artery in as many as up to 50% of the subjects studied angiographically, while ischemia provoking compression was believed to occur in only 1%.6
Traditionally, the diagnostic workup for MALS starts with mesenteric arterial duplex ultrasound. This study typically shows increased peak systolic velocities during expiration compared to inspiration, suggesting a more pronounced narrowing of the celiac artery in the former state. However, ultrasound has its limitations such as sonographer experience, patient body habitus and presence of bowel gas that may interfere with adequate image acquisition and thus may not reveal the underlying pathology. While CTA, MRA and conventional angiography are also able to demonstrate a dynamic stenosis in the proximal celiac artery when significant impingement from MAL is present, there is no input from these studies regarding the physiologic significance of such a stenosis. Endovascular treatment as the mainstay of therapy is not beneficial and as such is not advocated. Without relief of the extrinsic compression, stents in the celiac artery remain at risk of repetitive trauma, fragmentation and restenosis.7 Treatment for MALS consists of surgical decompression in the appropriately selected patients. In this procedure the fibers of MAL are divided. Additionally, celiac ganglionectomy is usually performed concomitantly. While open surgery remains the mainstay of therapy, laparoscopic as well as robot-assisted laparoscopic division of MAL has been performed with reasonable
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
320
Vascular Medicine 19(4)
Figure 5. CTA showing severe stenosis in the proximal celiac artery (white arrow) and no obstructive disease in the SMA (gray arrow). (A) Three-dimensional reconstruction image. (B) Sagittal reformatted CT image.
success. However, despite the minimally invasive nature of this procedure, the risk of vascular trauma and conversion to open surgery remains as high as 10–27%.8,9 Combined with celiac artery decompression, revascularization of this vessel either surgically or with angioplasty/ stenting has shown more promise in long-term remission of symptoms. Also, most but not all MALS patients derive significant relief from decompression.10 Therefore, it is incumbent upon the physician to demonstrate not only the presence of a stenosis in the celiac artery in a symptomatic patient but also the association between the detected stenosis and resultant mesenteric ischemia before subjecting the patient to a potentially risky surgery. While conventional imaging modalities used traditionally to make this diagnosis provide adequate anatomic details of the stenosis, they fail to provide any physiologic data. Measurement of a hemodynamically significant gradient across the stenosis would provide such information. While a catheter advanced across a stenosis has been used in the past to measure the gradient, this technique is unreliable and often results in overestimation of the gradient due to the obstruction caused by the catheter itself.11 Using a 0.014” pressure wire employed for measuring FFR offers a valuable alternative. FFR has been used extensively in the assessment of coronary artery disease to determine the physiologic significance of an underlying stenosis.12 This concept has been extrapolated to the non-coronary circulation as well and its use is now being suggested in the evaluation of visceral arterial stenosis.13–16 Our case demonstrates the successful use of a pressure wire in detecting the gradient across the celiac artery stenosis in MALS. In order to mimic the physiologic vasodilatory state that occurs in the post-prandial setting, we induced hyperemia and repeated the FFR. As expected, with hyperemia the gradient across the stenosis increased remarkably. Moreover, and importantly, we were able to show clearly that the gradient, whether baseline or hyperemic, worsened with expiration, thereby strengthening the concept of dynamic extrinsic compression of the celiac artery.
The use of IVUS in our patient not only demonstrated the stenosis but also that it was caused by the small caliber of the vessel rather than luminal narrowing caused by plaque formation. The IVUS findings most likely reflected longstanding extrinsic compression presumably by the median arcuate ligament. The dynamic component of the obstruction – baseline stenosis becoming more severe during expiration – was also obvious with this imaging modality. One other observation from our case is that, based on both FFR and IVUS data, at least in a subset of patients, the compression is present in both phases of respiration. This vignette clearly demonstrates that the celiac artery narrowing in MALS is an anatomical phenomenon with clear physiologic consequences that can explain the symptoms suggestive of chronic mesenteric ischemia. We propose the routine utilization of FFR, a simple but very useful diagnostic modality, in the invasive workup of patients suspected of MALS. This would allow the physicians to not only diagnose the condition with confidence but also to identify and possibly exclude those patients who would not benefit from surgical decompression therapy. We recognize that the ischemic threshold of FFR has not yet been established in mesenteric ischemic disease and, therefore, further studies are warranted. Declaration of conflicting interest The authors declare that there is no conflict of interest.
Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
References 1. Harjola PT. A rare obstruction of the coeliac artery: report of a case. Ann Chir Gynaecol Fenn 1963; 52: 547–550. 2. Dunbar JD, Molnar W, Beman FF, Marable SA. Compression of the celiac trunk and abdominal angina: preliminary report of 15 cases. AJR Am J Roentgenol 1965; 95: 731–744. 3. De Lara FV, Higgins C, Hernandez-Vila EA. Median arcuate ligament syndrome confirmed with the use of intravascular ultrasound. Tex Heart Inst J 2014; 41: 57–60. 4. Watson WC, Sadikali F. Celiac axis compression: experience with 20 patients and a critical appraisal of the syndrome. Ann Intern Med 1977; 86: 278–284. 5. Loukas M, Pinyard J, Vaid S, Kinsella C. Clinical anatomy of celiac artery compression syndrome: a review. Clin Anat 2007; 20: 612–617. 6. Cornell SH. Severe stenosis of the celiac artery. Analysis of patients with and without symptoms. Radiology 1971; 99: 311–316. 7. Delis KT, Gloviczki P, Altuwaijri M, McKusik MA. Median arcuate ligament syndrome: open celiac artery reconstruction and ligament division after endovascular failure. J Vasc Surg 2007; 46: 799–802. 8. Jimenez JC, Harlander-Locke M, Dutson EP. Open and laparoscopic treatment of median arcuate ligament syndrome. Vasc Surg 2012; 56: 869–873. 9. Roseborough GS. Laparoscopic management of celiac artery compression syndrome. J Vasc Surg 2009; 50: 124–133. 10. Jimenez JC, Harlander-Locke M, Dutson EP. Open and laparoscopic treatment of median arcuate ligament syndrome. J Vasc Surg 2012; 56: 869–873. 11. Colyer WR, Cooper CJ, Burket MW, Thomas WJ. Utility of a 0.014” pressure-sensing guidewire to assess renal artery
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
321
Sadiq et al. translesional systolic pressure gradients. Catheter Cardiovasc Interv 2003; 59: 372–377. 12. Tonino PAL, De Bruyne B, Pijls NH, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary angiography. N Engl J Med 2009; 360: 213–224. 13. Hannawi B, Lam WW, Younis GA. Pressure wire used to measure gradient in chronic mesenteric ischemia. Tex Heart Inst J 2012; 39: 739–743. 14. Prasad A, Zafar N, Mahmud E. Assessment of renal artery fibromuscular dysplasia: angiography, intravascular ultrasound
(with virtual histology), and pressure wire measurements. Catheter Cardiovasc Interv 2009; 74: 260–264. 15. De Bruyne B, Manoharan G, Pijls NH, et al. Assessment of renal artery stenosis severity by pressure gradient measurements. J Am Coll Cardiol 2006; 48: 1851–1855. 16. Leesar MA, Varma J, Shapira A, et al. Prediction of hypertension improvement after stenting of renal artery stenosis: comparative accuracy of translesional pressure gradients, intravascular ultrasound and angiography. J Am Coll Cardiol 2009; 25: 2363–2371.
Downloaded from vmj.sagepub.com at UNIV CALGARY LIBRARY on May 25, 2015
