Inferior phrenic artery–to–pulmonary artery fistula after surgery for catamenial pneumothorax: a case report

Inferior phrenic artery–to–pulmonary artery fistula after surgery for catamenial pneumothorax: a case report | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Inferior phrenic artery–to–pulmonary artery fistula after surgery for catamenial pneumothorax: a case report Sakiko Takahashi, Shigeo Hanada, Tomoya Tanishima, Daisuke Itoh, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9019736/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 20 You are reading this latest preprint version Abstract Background: Systemic artery–to–pulmonary artery fistula (SAPAF) is a rare vascular anomaly, and involvement of the inferior phrenic artery is particularly uncommon. Acquired SAPAF may occur as a late postoperative complication; however, diagnosis is often challenging because of subtle imaging findings and complex hemodynamics. Four-dimensional CT angiography (4D-CTA) enables time-resolved assessment of blood flow and may facilitate accurate diagnosis and treatment planning. Case presentation: A 56-year-old woman was referred to the respiratory department after screening chest CT, performed as part of an evaluation for suspected malignancy due to elevated tumor markers detected during a routine health checkup, revealed a suspected right pulmonary arteriovenous fistula. During further evaluation, it was confirmed that she had undergone thoracoscopic wedge resection of the right middle lobe and partial diaphragmatic resection for catamenial pneumothorax 10 years earlier. She was asymptomatic at presentation. Dynamic 4D-CTA demonstrated absence of opacification of the right A9 segmental pulmonary artery during the pulmonary arterial and venous phases, with retrograde filling of a tortuous vessel arising from the right inferior phrenic artery, suggesting an inferior phrenic artery–to–pulmonary artery fistula. Digital subtraction angiography confirmed the diagnosis, and coil embolization was successfully performed. Post-embolization angiography showed complete occlusion of the feeder artery and disappearance of the shunt. Conclusions: This case illustrates a previously unreported late postoperative complication after surgery for catamenial pneumothorax and highlights the clinical utility of 4D-CTA as a noninvasive modality for hemodynamic assessment and decision-making in the management of SAPAF. Inferior phrenic artery–to–pulmonary artery fistula systemic artery–to–pulmonary artery fistula catamenial pneumothorax four-dimensional CT angiography case report Figures Figure 1 Figure 2 Background Systemic artery–to–pulmonary artery fistula (SAPAF) is a rare vascular abnormality characterized by an abnormal shunt between a systemic artery and the pulmonary arterial circulation [ 1 – 6 ]. SAPAF can be congenital or acquired, and in the latter case it may develop after thoracic surgery, pneumothorax [ 7 ], infection [ 8 ], or chronic inflammation. Involvement of the inferior phrenic artery is particularly rare [ 6 ], and in most of the reported cases, the SAPAF originated from the bronchial or intercostal arteries. As SAPAF may mimic a pulmonary arteriovenous fistula or other pulmonary vascular disorders on conventional imaging [ 4 ], the accurate identification of the feeding artery and flow direction is essential for enabling appropriate management. Four-dimensional CT angiography (4D-CTA) is a dynamic imaging technique in which a fixed anatomical region is repeatedly scanned during rapid intravenous contrast injection, allowing time-resolved visualization of contrast flow. Unlike conventional static CT angiography, this approach enables intuitive assessment of flow direction and shunt hemodynamics, even for non-radiologists. In the present case, this temporal information was critical for distinguishing a systemic artery–to–pulmonary artery fistula from other vascular abnormalities and for selecting an appropriate embolization strategy [ 4 , 8 , 9 ]. We describe an inferior phrenic artery–to–pulmonary artery fistula that was incidentally identified nearly a decade after thoracoscopic surgical treatment of catamenial pneumothorax. This case suggests a possible contribution of endometriosis-related angiogenesis to postoperative vascular remodeling and highlights the complementary roles of 4D-CTA and selective angiography in diagnosis and treatment planning. Case presentation A 56-year-old woman was referred to our respiratory department after a vascular abnormality was detected on chest CT performed for malignancy screening. She had undergone a routine health checkup, during which serum tumor markers were found to be elevated. As part of a comprehensive evaluation to exclude malignancy, contrast-enhanced chest CT was performed and revealed a suspected abnormal vascular connection in the right lower lung field, raising suspicion of a pulmonary arteriovenous fistula. During further clinical evaluation, it was confirmed that the patient had undergone video-assisted thoracoscopic wedge resection of the right middle lobe and partial diaphragmatic resection for catamenial pneumothorax at the age of 46 years, approximately 10 years earlier. Her postoperative course had been uneventful, and there had been no recurrence of pneumothorax. At presentation, she was asymptomatic, without dyspnea, hemoptysis, or chest pain. Physical examination and routine laboratory findings were unremarkable. Chest CT revealed aneurysmal dilatation of the right A9 segmental pulmonary artery without identifiable drainage into the pulmonary vein, along with tortuous dilatation of the right inferior phrenic artery (Fig. 1 a, b). Three-dimensional CT reconstruction demonstrated a direct connection between these vessels (Fig. 1 c). Four-dimensional CT angiography showed absence of contrast opacification of the dilated A9 pulmonary artery during the pulmonary arterial phase, followed by retrograde opacification from the right inferior phrenic artery during the systemic arterial phase, suggesting a systemic artery–to–pulmonary artery fistula (Fig. 1 d, e). Pulmonary perfusion scintigraphy with technetium-99m macroaggregated albumin revealed a small intrapulmonary shunt fraction of 2.2%, while ventilation scintigraphy showed no defects. Although the shunt was hemodynamically small and conservative management was considered reasonable, endovascular treatment was selected after multidisciplinary discussion and patient preference. Subsequent celiac arteriography confirmed opacification of the pulmonary artery via the right inferior phrenic artery. Selective angiography demonstrated early filling of the right pulmonary vein, indicating a potential risk of systemic embolization with liquid embolic agents; therefore, coil embolization was selected (Fig. 2 a). Post-embolization angiography demonstrated complete occlusion of the right inferior phrenic artery with disappearance of the shunt (Fig. 2 b). The postprocedural course was uneventful, and follow-up CT performed one month later showed regression of the dilated vascular structures without recurrence. The patient expressed satisfaction that treatment could be performed to reduce the potential risk associated with the lesion and felt reassured after the procedure Discussion and Conclusions To our knowledge, this is the first report of an acquired SAPAF that originated from the inferior phrenic artery as a late postoperative complication of surgically treated catamenial pneumothorax. SAPAF is an uncommon but clinically important cause of abnormal pulmonary vascular findings and, in some patients, hemoptysis or hemothorax [ 2 , 4 , 5 ]. Inferior phrenic artery–to–pulmonary artery fistulas are particularly rare and have been described after pulmonary resection, pneumothorax surgery [ 7 ], and chronic inflammatory lung disease [ 2 ]. In this context, the pathogenesis of SAPAF is likely multifactorial, involving postoperative diaphragmatic remodeling, chronic inflammation, and angiogenic stimulation that is associated with thoracic endometriosis [ 10 – 12 ]. In our patient, the fistula appeared 10 years after thoracoscopic surgery for catamenial pneumothorax, which suggests that postoperative scarring at the diaphragm and lung base possibly promoted the formation of collaterals from the inferior phrenic artery to the pulmonary circulation. Catamenial pneumothorax is strongly associated with thoracic endometriosis [ 10 – 13 ], and ectopic endometrial tissue overexpresses angiogenic factors, such as vascular endothelial growth factor and fibroblast growth factors. The intrinsic angiogenic potential of endometriosis-related tissue, when superimposed on postoperative remodeling, potentially contributed to progressive systemic–pulmonary collateralization in this case; however, histologic confirmation is unavailable. A key strength of this case is the use of 4D-CTA, which enabled the dynamic visualization of blood flow as well as the accurate identification of the feeder artery. In contrast to conventional CT [ 1 , 4 , 14 ], 4D-CTA enables the assessment of contrast timing and flow direction, and thereby helps differentiate between an SAPAF and a pulmonary arteriovenous fistula [ 8 , 15 ]. The presence of early pulmonary venous drainage influenced the selection of treatment, as liquid embolic materials potentially posed a risk of systemic embolization. Coil embolization provided a controlled and safe therapeutic approach [ 1 , 3 , 16 , 17 ] that resulted in complete angiographic and clinical success. In summary, the possibility of an inferior phrenic artery–to–pulmonary artery fistula should be considered when abnormal basal vascular findings are detected after diaphragmatic surgery for catamenial pneumothorax. 4D-CTA, in combination with selective angiography, enables accurate diagnosis as well as the safe planning of coil embolization. Several limitations of this report should be acknowledged. First, this is a single-case report, which limits the generalizability of the findings. Second, although four-dimensional CT angiography was informative in this case, its routine clinical use may be constrained by potentially increased radiation exposure and limited availability. In conclusion, inferior phrenic artery–to–pulmonary artery fistula should be considered in patients with prior thoracic surgery who present with unexplained vascular abnormalities near the diaphragm. In this context, 4D-CTA is a powerful noninvasive diagnostic tool for evaluating patients with suspected SAPAF and can play a crucial role in guiding safe and effective endovascular management. Abbreviations 4D-CTA Four-dimensional computed tomographic angiography A9 Anterior basal segmental branch of the right pulmonary artery DSA Digital subtraction angiography IFPA Inferior phrenic artery IR Interventional radiology MAA Macroaggregated albumin SAPAF Systemic artery–to–pulmonary artery fistula VATS Video-assisted thoracoscopic surgery Declarations Acknowledgements The authors would like to thank Editage (www.editage.com) for English language editing. Authors’ contributions All authors contributed to the conception and design of the study. ST and SH collected clinical data, wrote the initial draft of the manuscript. ST, TT, DI, and KO evaluated the radiological findings and performed interventional radiology. TT, DI, ET, HN, YT, YN, TM, AM, KO and MT supervised the study and revised the manuscript. All authors have read and approved the final version of the manuscript. Funding No funding was received for the conception, composition, editing, or submission of this manuscript. Availability of data and materials All data generated or analysed during this study are included in this published article. No additional datasets were generated or analysed. Ethics approval This case was reported in accordance with the Declaration of Helsinki. Formal institutional review board approval was not required for a single-patient case report at our institution. Consent for publication The patient provided written informed consent for the publication of the clinical details and images. Competing interest s The authors declare no conflicts of interest and no relevant financial relationships to disclose. References Lee JK, Park JH, Kim J, Kim SJ, Lee AR, Lee CH, et al. Embolization of multiple systemic artery to pulmonary artery fistula with recurrent hemoptysis. Tuberc Respir Dis (Seoul). 2013;75:120-4. Yakushiji E, Ota S, Komatsu T, Ayaori M, Ikewaki K. Massive hemoptysis due to right inferior phrenic artery-to-right pulmonary artery fistula in the right middle lobe of the lung. Intern Med . 2017;56:687–9, doi: 10.2169/internalmedicine.56.6783 Kawakado K, Yabuki T, Nishi T, Nakanishi M, Makimoto G, Tamura T, et al. Successful transcatheter arterial embolization of an asymptomatic aneurysm associated with inferior phrenic artery–to–pulmonary artery fistula. a case report. Respir Med Case Rep . 2021;33:101444. doi: 10.1016/j.rmcr.2021.101444. Woo JH, Cha YK, Lee SY, Kim JH, Kim JG, Son Y, et al. CT evaluation of systemic artery–to–pulmonary artery fistula: an underdiagnosed disease in patients with hemoptysis. J Thorac Dis . 2023;15:5952–60. doi: 10.21037/jtd-23-861. D’Angelo A, Khan H, Coleman G, Masood I. Right inferior phrenic artery to right pulmonary artery fistula causing hemothorax: a case report. Radiol Case Rep. 2024;19:3273-5. Yuan J, Irani FG, Tan MO. Transpleural inferior phrenic artery–to–pulmonary artery fistula incidentally detected on CT. Cardiovasc Interv Radiol . 2024;47:892–5. doi: 10.1007/s00270-024-03658-1. Jacheć W, Tomasik A, Kurzyna M, Pietura R, Torbicki A, Głowacki J, et al. The multiple systemic artery to pulmonary artery fistulas resulting in severe irreversible pulmonary arterial hypertension in patient with previous history of pneumothorax. BMC Pulm Med . 2019;19:144. doi: 10.1186/s12890-019-0832-8. Estephan T, Ridley L, Xiang H, Yeong C, Chan MV, Loke J. ‘Bronchial artery to pulmonary artery fistula in a patient with cavitating tuberculosis-Demonstration with 4D CTA. Radiol Case Rep . 2023;18:1065–8. doi: 10.1016/j.radcr.2022.12.025. Livingston D, Grove M, Grage R, McKinney JM. Systemic artery–to–pulmonary artery fistula mimics pulmonary embolus: a case report with imaging review and literature summary. J Clin Imaging Sci . 2019;9:41. doi: 10.25259/JCIS_54_2019 PMID: 31583179. Korom S, Canyurt H, Missbach A, Schneiter D, Kurrer MO, Haller U, et al. Catamenial pneumothorax revisited: clinical approach and systematic review of the literature. J Thorac Cardiovasc Surg . 2004;128:502–8. doi: 10.1016/j.jtcvs.2004.04.039. Legras A, Mansuet-Lupo A, Rousset-Jablonski C, Bobbio A, Magdeleinat P, Roche N, et al. Pneumothorax in women of child-bearing age: an update classification based on clinical and pathologic findings. Chest . 2014;145:354–60. doi: 10.1378/chest.13-1284. Nezhat C, Lindheim SR, Backhus L, Vu M, Vang N, Nezhat A, et al. Thoracic endometriosis syndrome: a review of diagnosis and management. JSLS . 2019;23:e2019.00029. doi: 10.4293/JSLS.2019.00029. Alifano M, Roth T, Broët SC, Schussler O, Magdeleinat P, Regnard JF. Catamenial pneumothorax: a prospective study. Chest. 2003;124:1004-8. Zhang YF, Zhao Q, Huang R. Computed tomography angiography for presence of systemic-to-pulmonary artery shunt in transpleural systemic arterial supply. Eur J Radiol. 2020;129:109060. Zagurovskaya M, Issa M, Winkler M. Systemic artery-pulmonary artery fistulae of adult bronchopulmonary dysplasia characterized with dynamic CT angiography and multiphase 3D-volumetric reconstruction: a case report. Cardiovasc Diagn Ther . 2019;9:55–9, doi: 10.21037/cdt.2018.09.01 Wynne DM, Jefferson XD. Coil embolization of an inferior phrenic artery–to–pulmonary artery fistula. J Vasc Interv Radiol . 2022;33:736–8. doi: 10.1016/j.jvir.2022.03.017. Shen B, Xu J, Ma X, Jiang S. Endovascular embolization of a congenital inferior phrenic artery–to–pulmonary arteriovenous malformation: a rare case report. BMC Pulm Med . 2024;24:324. doi: 10.1186/s12890-024-03324-y. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 04 May, 2026 Reviews received at journal 01 May, 2026 Reviews received at journal 21 Apr, 2026 Reviews received at journal 20 Apr, 2026 Reviews received at journal 19 Apr, 2026 Reviews received at journal 17 Apr, 2026 Reviews received at journal 15 Apr, 2026 Reviews received at journal 15 Apr, 2026 Reviewers agreed at journal 14 Apr, 2026 Reviewers agreed at journal 12 Apr, 2026 Reviewers agreed at journal 11 Apr, 2026 Reviewers agreed at journal 11 Apr, 2026 Reviewers agreed at journal 11 Apr, 2026 Reviewers agreed at journal 09 Apr, 2026 Reviewers agreed at journal 09 Apr, 2026 Reviewers invited by journal 02 Apr, 2026 Editor assigned by journal 31 Mar, 2026 Editor invited by journal 09 Mar, 2026 Submission checks completed at journal 06 Mar, 2026 First submitted to journal 06 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9019736","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":618821438,"identity":"a0d4836e-7e21-4c64-934c-c4519c8c8b6c","order_by":0,"name":"Sakiko Takahashi","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Sakiko","middleName":"","lastName":"Takahashi","suffix":""},{"id":618821439,"identity":"ff1eb57e-33ca-4f84-9374-aed582be1fac","order_by":1,"name":"Shigeo Hanada","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA90lEQVRIiWNgGAWjYPCCAyDCgOEDA0MCVISNOC2MM0jWwsyD0IIbyLv3mH342HZH3pz98MbPtm12efzsDYwfPjDw5eHSYnjmjPHMmW3PDHf2pBVL57YlF0v2HGCWnMHAVoxTy4wcY2betsOMGw7kGAC1MCduuJHABnQhW2IDAS32G86/Mf5t2VZPWIu8BEQLUGWOmTQjmEFAiwHPsWLGGecOJ2+48azMsufc8cSZPQebJWcY4PaLfHvzZoYPZYdtN5xP3nzjR1l1Yj9788EPHyqO4QwxgwPIPEZwBDICnWRwLAGnLagu/gNn1eDUMgpGwSgYBSMOAAAbjlwxuL49pwAAAABJRU5ErkJggg==","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":true,"prefix":"","firstName":"Shigeo","middleName":"","lastName":"Hanada","suffix":""},{"id":618821441,"identity":"adc733e1-be06-4961-b2ed-e65f8ed648d8","order_by":2,"name":"Tomoya Tanishima","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Tomoya","middleName":"","lastName":"Tanishima","suffix":""},{"id":618821442,"identity":"0bd01538-655d-4067-8abf-d33a18ea2169","order_by":3,"name":"Daisuke Itoh","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Daisuke","middleName":"","lastName":"Itoh","suffix":""},{"id":618821446,"identity":"4de7e0ff-8349-47e1-86c5-3145d5752cc1","order_by":4,"name":"Eisuke Takeda","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Eisuke","middleName":"","lastName":"Takeda","suffix":""},{"id":618821447,"identity":"d9fca387-3a5c-426b-937c-593e42ba8c44","order_by":5,"name":"Hiroshi Nakahama","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Hiroshi","middleName":"","lastName":"Nakahama","suffix":""},{"id":618821451,"identity":"e8db0252-2f5a-41e8-962b-2646dfb4614a","order_by":6,"name":"Yui Takahashi","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yui","middleName":"","lastName":"Takahashi","suffix":""},{"id":618821454,"identity":"02a211a1-8e6b-4860-90f2-2519389baf5f","order_by":7,"name":"Yuichiro Nei","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yuichiro","middleName":"","lastName":"Nei","suffix":""},{"id":618821456,"identity":"6dcda8bf-597e-4a50-9ee9-a8088424fcba","order_by":8,"name":"Takahiro Mitsumura","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Takahiro","middleName":"","lastName":"Mitsumura","suffix":""},{"id":618821458,"identity":"ee024aa9-7ca5-42e2-a8fc-db251dea1e04","order_by":9,"name":"Atsushi Miyamoto","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Atsushi","middleName":"","lastName":"Miyamoto","suffix":""},{"id":618821461,"identity":"d10532ee-254a-432e-a5f4-46be40bd8aef","order_by":10,"name":"Katsunori Oikado","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Katsunori","middleName":"","lastName":"Oikado","suffix":""},{"id":618821462,"identity":"c042361a-41ce-4ecf-8f6c-814cf5e1fae8","order_by":11,"name":"Meiyo Tamaoka","email":"","orcid":"","institution":"Toranomon Hospital","correspondingAuthor":false,"prefix":"","firstName":"Meiyo","middleName":"","lastName":"Tamaoka","suffix":""}],"badges":[],"createdAt":"2026-03-03 11:38:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9019736/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9019736/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106399591,"identity":"6dbbe78e-461d-44b3-93e5-5ba26079176e","added_by":"auto","created_at":"2026-04-08 08:30:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":30171692,"visible":true,"origin":"","legend":"\u003cp\u003eMultimodal CT evaluation of an inferior phrenic artery–to–pulmonary artery fistula. (a) Chest CT with lung window setting shows aneurysmal dilatation of the right A9 segmental pulmonary artery without identifiable drainage into the pulmonary vein. (b) Contrast-enhanced chest CT with mediastinal window setting demonstrates tortuous dilatation of the right inferior phrenic artery adjacent to the right hemidiaphragm. (c) Three-dimensional CT reconstruction demonstrates a direct connection between the right A9 segmental pulmonary artery and the right inferior phrenic artery (arrow and arrowhead). (d) Four-dimensional CT angiography (pulmonary arterial phase) shows absence of contrast opacification of the dilated peripheral right A9 pulmonary artery. (e) Four-dimensional CT angiography (systemic arterial phase) demonstrates retrograde opacification of the dilated peripheral right A9 pulmonary artery supplied by the right inferior phrenic artery, consistent with an inferior phrenic artery–to–pulmonary artery fistula.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-9019736/v1/a1dbd109dd83c2ae7337931b.png"},{"id":106404640,"identity":"f34dbaaf-e58a-4161-bd4e-72dc6695a6de","added_by":"auto","created_at":"2026-04-08 09:16:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":11712424,"visible":true,"origin":"","legend":"\u003cp\u003eAngiographic confirmation and endovascular treatment of the inferior phrenic artery–to–pulmonary artery fistula. (a) Celiac arteriography demonstrates opacification of the pulmonary artery via the right inferior phrenic artery. Selective angiography further reveals early filling of the right pulmonary vein (arrows), indicating a potential risk of systemic embolization with liquid embolic agents; therefore, coil embolization was selected. (b) Post-embolization angiography confirms complete occlusion of the right inferior phrenic artery with disappearance of the arteriovenous shunt.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-9019736/v1/4a0ec1d82ae3e82259ecc87f.png"},{"id":106405978,"identity":"1b28613f-6ae7-43f6-b828-f3f80d72c778","added_by":"auto","created_at":"2026-04-08 09:29:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":36408167,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9019736/v1/42b4ec55-807d-4805-84fb-b2aee72c587b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Inferior phrenic artery–to–pulmonary artery fistula after surgery for catamenial pneumothorax: a case report","fulltext":[{"header":"Background","content":"\u003cp\u003eSystemic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula (SAPAF) is a rare vascular abnormality characterized by an abnormal shunt between a systemic artery and the pulmonary arterial circulation [\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. SAPAF can be congenital or acquired, and in the latter case it may develop after thoracic surgery, pneumothorax [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], infection [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], or chronic inflammation. Involvement of the inferior phrenic artery is particularly rare [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], and in most of the reported cases, the SAPAF originated from the bronchial or intercostal arteries. As SAPAF may mimic a pulmonary arteriovenous fistula or other pulmonary vascular disorders on conventional imaging [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], the accurate identification of the feeding artery and flow direction is essential for enabling appropriate management. Four-dimensional CT angiography (4D-CTA) is a dynamic imaging technique in which a fixed anatomical region is repeatedly scanned during rapid intravenous contrast injection, allowing time-resolved visualization of contrast flow. Unlike conventional static CT angiography, this approach enables intuitive assessment of flow direction and shunt hemodynamics, even for non-radiologists. In the present case, this temporal information was critical for distinguishing a systemic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula from other vascular abnormalities and for selecting an appropriate embolization strategy [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe describe an inferior phrenic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula that was incidentally identified nearly a decade after thoracoscopic surgical treatment of catamenial pneumothorax. This case suggests a possible contribution of endometriosis-related angiogenesis to postoperative vascular remodeling and highlights the complementary roles of 4D-CTA and selective angiography in diagnosis and treatment planning.\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003eA 56-year-old woman was referred to our respiratory department after a vascular abnormality was detected on chest CT performed for malignancy screening. She had undergone a routine health checkup, during which serum tumor markers were found to be elevated. As part of a comprehensive evaluation to exclude malignancy, contrast-enhanced chest CT was performed and revealed a suspected abnormal vascular connection in the right lower lung field, raising suspicion of a pulmonary arteriovenous fistula. During further clinical evaluation, it was confirmed that the patient had undergone video-assisted thoracoscopic wedge resection of the right middle lobe and partial diaphragmatic resection for catamenial pneumothorax at the age of 46 years, approximately 10 years earlier. Her postoperative course had been uneventful, and there had been no recurrence of pneumothorax. At presentation, she was asymptomatic, without dyspnea, hemoptysis, or chest pain. Physical examination and routine laboratory findings were unremarkable.\u003c/p\u003e \u003cp\u003eChest CT revealed aneurysmal dilatation of the right A9 segmental pulmonary artery without identifiable drainage into the pulmonary vein, along with tortuous dilatation of the right inferior phrenic artery (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ea, b). Three-dimensional CT reconstruction demonstrated a direct connection between these vessels (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec). Four-dimensional CT angiography showed absence of contrast opacification of the dilated A9 pulmonary artery during the pulmonary arterial phase, followed by retrograde opacification from the right inferior phrenic artery during the systemic arterial phase, suggesting a systemic artery–to–pulmonary artery fistula (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed, e). Pulmonary perfusion scintigraphy with technetium-99m macroaggregated albumin revealed a small intrapulmonary shunt fraction of 2.2%, while ventilation scintigraphy showed no defects. Although the shunt was hemodynamically small and conservative management was considered reasonable, endovascular treatment was selected after multidisciplinary discussion and patient preference.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSubsequent celiac arteriography confirmed opacification of the pulmonary artery via the right inferior phrenic artery. Selective angiography demonstrated early filling of the right pulmonary vein, indicating a potential risk of systemic embolization with liquid embolic agents; therefore, coil embolization was selected (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea). Post-embolization angiography demonstrated complete occlusion of the right inferior phrenic artery with disappearance of the shunt (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb). The postprocedural course was uneventful, and follow-up CT performed one month later showed regression of the dilated vascular structures without recurrence. The patient expressed satisfaction that treatment could be performed to reduce the potential risk associated with the lesion and felt reassured after the procedure\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e "},{"header":"Discussion and Conclusions","content":"\u003cp\u003eTo our knowledge, this is the first report of an acquired SAPAF that originated from the inferior phrenic artery as a late postoperative complication of surgically treated catamenial pneumothorax. SAPAF is an uncommon but clinically important cause of abnormal pulmonary vascular findings and, in some patients, hemoptysis or hemothorax [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e]. Inferior phrenic artery–to–pulmonary artery fistulas are particularly rare and have been described after pulmonary resection, pneumothorax surgery [\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e], and chronic inflammatory lung disease [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e]. In this context, the pathogenesis of SAPAF is likely multifactorial, involving postoperative diaphragmatic remodeling, chronic inflammation, and angiogenic stimulation that is associated with thoracic endometriosis [\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e–\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e]. In our patient, the fistula appeared 10 years after thoracoscopic surgery for catamenial pneumothorax, which suggests that postoperative scarring at the diaphragm and lung base possibly promoted the formation of collaterals from the inferior phrenic artery to the pulmonary circulation. Catamenial pneumothorax is strongly associated with thoracic endometriosis [\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e–\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e], and ectopic endometrial tissue overexpresses angiogenic factors, such as vascular endothelial growth factor and fibroblast growth factors. The intrinsic angiogenic potential of endometriosis-related tissue, when superimposed on postoperative remodeling, potentially contributed to progressive systemic–pulmonary collateralization in this case; however, histologic confirmation is unavailable.\u003c/p\u003e\u003cp\u003eA key strength of this case is the use of 4D-CTA, which enabled the dynamic visualization of blood flow as well as the accurate identification of the feeder artery. In contrast to conventional CT [\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e], 4D-CTA enables the assessment of contrast timing and flow direction, and thereby helps differentiate between an SAPAF and a pulmonary arteriovenous fistula [\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e]. The presence of early pulmonary venous drainage influenced the selection of treatment, as liquid embolic materials potentially posed a risk of systemic embolization. Coil embolization provided a controlled and safe therapeutic approach [\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e] that resulted in complete angiographic and clinical success. In summary, the possibility of an inferior phrenic artery–to–pulmonary artery fistula should be considered when abnormal basal vascular findings are detected after diaphragmatic surgery for catamenial pneumothorax. 4D-CTA, in combination with selective angiography, enables accurate diagnosis as well as the safe planning of coil embolization. Several limitations of this report should be acknowledged. First, this is a single-case report, which limits the generalizability of the findings. Second, although four-dimensional CT angiography was informative in this case, its routine clinical use may be constrained by potentially increased radiation exposure and limited availability.\u003c/p\u003e\u003cp\u003eIn conclusion, inferior phrenic artery–to–pulmonary artery fistula should be considered in patients with prior thoracic surgery who present with unexplained vascular abnormalities near the diaphragm. In this context, 4D-CTA is a powerful noninvasive diagnostic tool for evaluating patients with suspected SAPAF and can play a crucial role in guiding safe and effective endovascular management.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e4D-CTA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFour-dimensional computed tomographic angiography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eA9\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAnterior basal segmental branch of the right pulmonary artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDSA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDigital subtraction angiography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIFPA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInferior phrenic artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInterventional radiology\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMAA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMacroaggregated albumin\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSAPAF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSystemic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eVATS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eVideo-assisted thoracoscopic surgery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank Editage (www.editage.com) for English language editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the conception and design of the study. ST and SH collected clinical data, wrote the initial draft of the manuscript. ST, TT, DI, and KO evaluated the radiological findings and performed interventional radiology. TT, DI, ET, HN, YT, YN, TM, AM, KO and MT supervised the study and revised the manuscript. All authors have read and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for the conception, composition, editing, or submission of this manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during this study are included in this published article. No additional datasets were generated or analysed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis case was reported in accordance with the Declaration of Helsinki. Formal institutional review board approval was not required for a single-patient case report at our institution.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patient provided written informed consent for the publication of the clinical details and images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interest\u003c/strong\u003e\u003cstrong\u003es\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflicts of interest and no relevant financial relationships to disclose.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eLee JK, Park JH, Kim J, Kim SJ, Lee AR, Lee CH, et al. Embolization of multiple systemic artery to pulmonary artery fistula with recurrent hemoptysis. Tuberc Respir Dis (Seoul). 2013;75:120-4.\u003c/li\u003e\n\u003cli\u003eYakushiji E, Ota S, Komatsu T, Ayaori M, Ikewaki K. Massive hemoptysis due to right inferior phrenic artery-to-right pulmonary artery fistula in the right middle lobe of the lung. Intern Med\u003cem\u003e.\u003c/em\u003e 2017;56:687\u0026ndash;9, doi: 10.2169/internalmedicine.56.6783\u003c/li\u003e\n\u003cli\u003eKawakado K, Yabuki T, Nishi T, Nakanishi M, Makimoto G, Tamura T, et al. Successful transcatheter arterial embolization of an asymptomatic aneurysm associated with inferior phrenic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula. a case report. Respir Med Case Rep\u003cem\u003e.\u003c/em\u003e 2021;33:101444. doi: 10.1016/j.rmcr.2021.101444.\u003c/li\u003e\n\u003cli\u003eWoo JH, Cha YK, Lee SY, Kim JH, Kim JG, Son Y, et al. CT evaluation of systemic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula: an underdiagnosed disease in patients with hemoptysis. J Thorac Dis\u003cem\u003e.\u003c/em\u003e 2023;15:5952\u0026ndash;60. doi: 10.21037/jtd-23-861.\u003c/li\u003e\n\u003cli\u003eD\u0026rsquo;Angelo A, Khan H, Coleman G, Masood I. Right inferior phrenic artery to right pulmonary artery fistula causing hemothorax: a case report. Radiol Case Rep. 2024;19:3273-5.\u003c/li\u003e\n\u003cli\u003eYuan J, Irani FG, Tan MO. Transpleural inferior phrenic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula incidentally detected on CT. Cardiovasc Interv Radiol\u003cem\u003e.\u003c/em\u003e 2024;47:892\u0026ndash;5. doi: 10.1007/s00270-024-03658-1.\u003c/li\u003e\n\u003cli\u003eJacheć W, Tomasik A, Kurzyna M, Pietura R, Torbicki A, Głowacki J, et al. The multiple systemic artery to pulmonary artery fistulas resulting in severe irreversible pulmonary arterial hypertension in patient with previous history of pneumothorax. BMC Pulm Med\u003cem\u003e.\u003c/em\u003e 2019;19:144. doi: 10.1186/s12890-019-0832-8.\u003c/li\u003e\n\u003cli\u003eEstephan T, Ridley L, Xiang H, Yeong C, Chan MV, Loke J. \u0026lsquo;Bronchial artery to pulmonary artery fistula in a patient with cavitating tuberculosis-Demonstration with 4D CTA. Radiol Case Rep\u003cem\u003e.\u003c/em\u003e 2023;18:1065\u0026ndash;8. doi: 10.1016/j.radcr.2022.12.025.\u003c/li\u003e\n\u003cli\u003eLivingston D, Grove M, Grage R, McKinney JM. Systemic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula mimics pulmonary embolus: a case report with imaging review and literature summary. J Clin Imaging Sci\u003cem\u003e.\u003c/em\u003e 2019;9:41. doi: 10.25259/JCIS_54_2019\u003cbr\u003e PMID: 31583179.\u003c/li\u003e\n\u003cli\u003eKorom S, Canyurt H, Missbach A, Schneiter D, Kurrer MO, Haller U, et al. Catamenial pneumothorax revisited: clinical approach and systematic review of the literature. J Thorac Cardiovasc Surg\u003cem\u003e.\u003c/em\u003e 2004;128:502\u0026ndash;8. doi: 10.1016/j.jtcvs.2004.04.039.\u003c/li\u003e\n\u003cli\u003eLegras A, Mansuet-Lupo A, Rousset-Jablonski C, Bobbio A, Magdeleinat P, Roche N, et al. Pneumothorax in women of child-bearing age: an update classification based on clinical and pathologic findings. Chest\u003cem\u003e.\u003c/em\u003e 2014;145:354\u0026ndash;60. doi: 10.1378/chest.13-1284.\u003c/li\u003e\n\u003cli\u003eNezhat C, Lindheim SR, Backhus L, Vu M, Vang N, Nezhat A, et al. Thoracic endometriosis syndrome: a review of diagnosis and management. JSLS\u003cem\u003e.\u003c/em\u003e 2019;23:e2019.00029. doi: 10.4293/JSLS.2019.00029.\u003c/li\u003e\n\u003cli\u003eAlifano M, Roth T, Bro\u0026euml;t SC, Schussler O, Magdeleinat P, Regnard JF. Catamenial pneumothorax: a prospective study. Chest. 2003;124:1004-8.\u003c/li\u003e\n\u003cli\u003eZhang YF, Zhao Q, Huang R. Computed tomography angiography for presence of systemic-to-pulmonary artery shunt in transpleural systemic arterial supply. Eur J Radiol. 2020;129:109060.\u003c/li\u003e\n\u003cli\u003eZagurovskaya M, Issa M, Winkler M. Systemic artery-pulmonary artery fistulae of adult bronchopulmonary dysplasia characterized with dynamic CT angiography and multiphase 3D-volumetric reconstruction: a case report. Cardiovasc Diagn Ther\u003cem\u003e.\u003c/em\u003e 2019;9:55\u0026ndash;9, doi: 10.21037/cdt.2018.09.01\u003c/li\u003e\n\u003cli\u003eWynne DM, Jefferson XD. Coil embolization of an inferior phrenic artery\u0026ndash;to\u0026ndash;pulmonary artery fistula. J Vasc Interv Radiol\u003cem\u003e.\u003c/em\u003e 2022;33:736\u0026ndash;8. doi: 10.1016/j.jvir.2022.03.017.\u003c/li\u003e\n\u003cli\u003eShen B, Xu J, Ma X, Jiang S. Endovascular embolization of a congenital inferior phrenic artery\u0026ndash;to\u0026ndash;pulmonary arteriovenous malformation: a rare case report. BMC Pulm Med\u003cem\u003e.\u003c/em\u003e 2024;24:324. doi: 10.1186/s12890-024-03324-y.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pulmonary-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pulm","sideBox":"Learn more about [BMC Pulmonary Medicine](http://bmcpulmmed.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pulm/default.aspx","title":"BMC Pulmonary Medicine","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Inferior phrenic artery–to–pulmonary artery fistula, systemic artery–to–pulmonary artery fistula, catamenial pneumothorax, four-dimensional CT angiography, case report","lastPublishedDoi":"10.21203/rs.3.rs-9019736/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9019736/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Systemic artery–to–pulmonary artery fistula (SAPAF) is a rare vascular anomaly, and involvement of the inferior phrenic artery is particularly uncommon. Acquired SAPAF may occur as a late postoperative complication; however, diagnosis is often challenging because of subtle imaging findings and complex hemodynamics. Four-dimensional CT angiography (4D-CTA) enables time-resolved assessment of blood flow and may facilitate accurate diagnosis and treatment planning.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCase presentation:\u003c/strong\u003e A 56-year-old woman was referred to the respiratory department after screening chest CT, performed as part of an evaluation for suspected malignancy due to elevated tumor markers detected during a routine health checkup, revealed a suspected right pulmonary arteriovenous fistula. During further evaluation, it was confirmed that she had undergone thoracoscopic wedge resection of the right middle lobe and partial diaphragmatic resection for catamenial pneumothorax 10 years earlier. She was asymptomatic at presentation. Dynamic 4D-CTA demonstrated absence of opacification of the right A9 segmental pulmonary artery during the pulmonary arterial and venous phases, with retrograde filling of a tortuous vessel arising from the right inferior phrenic artery, suggesting an inferior phrenic artery–to–pulmonary artery fistula. Digital subtraction angiography confirmed the diagnosis, and coil embolization was successfully performed. Post-embolization angiography showed complete occlusion of the feeder artery and disappearance of the shunt.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e This case illustrates a previously unreported late postoperative complication after surgery for catamenial pneumothorax and highlights the clinical utility of 4D-CTA as a noninvasive modality for hemodynamic assessment and decision-making in the management of SAPAF.\u003c/p\u003e","manuscriptTitle":"Inferior phrenic artery–to–pulmonary artery fistula after surgery for catamenial pneumothorax: a case report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-08 08:30:51","doi":"10.21203/rs.3.rs-9019736/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-04T16:16:47+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T14:37:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-21T04:34:30+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-20T05:46:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-19T10:33:38+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-17T08:10:43+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-15T20:39:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-15T19:44:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"64687809368260846634575633107582528312","date":"2026-04-14T20:18:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"214042388099897515631768001461403980276","date":"2026-04-12T11:20:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"47960562032718618161048726250062293351","date":"2026-04-11T09:54:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"166258703749343327257729627159252908257","date":"2026-04-11T06:28:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"293400149894407050390104835704679148012","date":"2026-04-11T05:57:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"126235867603666848398942671527002125963","date":"2026-04-09T16:14:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"138101440747369370031522803500672776609","date":"2026-04-09T06:20:34+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-02T08:45:40+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-31T12:17:49+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-09T16:51:37+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-06T23:59:38+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pulmonary Medicine","date":"2026-03-06T23:54:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pulmonary-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pulm","sideBox":"Learn more about [BMC Pulmonary Medicine](http://bmcpulmmed.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pulm/default.aspx","title":"BMC Pulmonary Medicine","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b0619cc4-5a09-4fc1-a5f4-012c88b4b803","owner":[],"postedDate":"April 8th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-04T16:16:47+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-01T14:37:51+00:00","index":79,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-15T23:38:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-08 08:30:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9019736","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9019736","identity":"rs-9019736","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}