下腔静脉发育不全伴奇静脉和半奇静脉肥大及腹腔侧支静脉网络形成：临床病例

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Introduction

Hypoplasia or the absence of the inferior vena cava (IVC) is a rare congenital condition that causes venous return from the lower body through the azygos or hemiazygos venous system [1, 2]. The IVC may be hypoplastic or absent and is termed “interrupted” in this case: this term refers to total agenesis.

In most cases, this vascular anomaly is due to some embryologic mechanisms, and a failed anastomosis exists between the right subcardinal vein and the vitelline vein, resulting in hypoplasia or, in some cases, agenesis of the infrarenal/subrenal IVC and an interruption at the suprarenal venous segment [3].

In some cases, the newborn suprahepatic IVC could be missing or hypoplastic, resulting in direct outflow into the right atrium [4]. In this case, the small suprarenal IVC in the hepatic hilum drains through the azygos vein, while the hepatic IVC exclusively receives the hepatic veins. These anatomical variants are asymptomatic if the azygos/hemiazygos continuation is well-developed and the venous collateral loop is intact [5]. However, recurrent deep vein thrombosis of the lower limbs, leg swelling, leg pain, varices of the lower extremities, abdominal pain, and hematochezia in rare cases may present in the future [6, 7]. Asymptomatic conditions are frequently discovered in the early to middle years of life, as in this case.

Description of the case

Anamnesis

A 75-year-old Caucasian man presented to the emergency department after a referred fall and underwent his first contrast-enhanced computed tomography (CT). A multiphase examination was performed using a 64-detector scanner, beginning with an unenhanced scan and progressing to postcontrast scans of the arterial and portal venous phases.

Diagnostic assessment and differential diagnosis

CT did not detect fractures, and no consequences visible under a radiological examination were observed. However, during imaging, the radiologist detected an unknown venous anomaly in the chest and abdomen.

The patient was not aware of this variant in the vascular anatomy and had never had symptoms related to it (Fig. 1).

 

Fig. 1. Computed tomography images of the axial section of the abdomen (portal phase): a) The small suprarenal IVC is indicated by a yellow asterisk. b) Lower in the abdomen, the yellow asterisk indicates the hypoplastic IVC, and the hypertrophic collateral venous circles in the anterior abdomen wall on the right are indicated by a white asterisk. c) Another lower axial section showing the small IVC (yellow asterisk). d) The drainage on the right side is accomplished by a constant iliac vessel (yellow asterisk).

 

Interventions

To adequately study this vascular anomaly, postprocessing reconstruction was conducted on all planes (axial, coronal, and sagittal) using the MIP program, and 3D images were generated.

At first glance, the most evident imaging finding of the vascular anomaly was the presence of multiple collateral venous circles on the anterior wall of the abdomen, particularly on the right side, and the IVC under the kidneys was hypoplastic (Fig. 2).

 

Fig. 2. Computed tomography images of the coronal (up) and sagittal (down) sections in the portal phase of the chest and abdomen: a) Right abdominal wall: consistent venous collateral circles are visible (white asterisk). b) The same image with a rising MIP value indicates venous collateral rings, particularly on the patient’s right side. c) and d) Hypertrophic venous collateral circles in the sagittal section at different levels.

 

Certain distended azygos and hemiazygos veins received blood from the abdomen. The azygos vein connected with the superior vena cava (SVC) through its arch; however, its dimensions were abnormal. It began from D7 and extended to D10–11, from the confluence of the right renal vein, transhepatic vein, and an aberrant vein (Fig. 3 and Fig. 4).

 

Fig. 3. Computed tomography images of the coronal section and portal phase of the chest and abdomen: a) The white asterisk indicates the confluence of the giant azygos, hemiazygos, and an aberrant vein. b) Same image at different sections. The yellow asterisk on the right side at the level of the anterior abdominal wall indicates marked collateral vein circles.

 

Fig. 4. Computed tomography images of the axial section of the chest: the confluence with the hypertrophic azygos and hemiazygos veins is seen in all images at different levels (from upper to lower). In a) and b), the white asterisk marks the confluence of the collateral circles of the abdomen and chest.

 

Follow-up and outcomes

The patient had previously never experienced symptoms that could be correlated with the same vascular abnormality, and the symptoms he experienced did not appear to be related. Therefore, periodic follow-up was recommended.

Discussion

The IVC is a large retroperitoneal vein that transports deoxygenated blood from the lower extremities, pelvis, and abdomen to the right atrium. The azygos venous system is a paravertebral connection in the posterior thorax that connects the SVC to the IVC. The azygos, hemiazygos, accessory hemiazygos, and left superior intercostal veins form a H-shaped pattern, indicating the azygos venous system [2, 3]. IVC hypoplasia, characterized by an azygos/hemiazygos system and collateral circle compensation, is an uncommon vascular defect with numerous variations [4-8]. The anomaly is primarily caused by the abnormal regression or persistence of embryological veins (anterocardinal, postcardinal, subcardinal, supracardinal, and vitelline) that form the five embryological segments of the final structure of the IVC, namely, iliac, subrenal, renal, suprarenal, and hepatic, including suprahepatic and retrohepatic [9]. In this case, the patient had a very small IVC in the right iliac fossa, with larger azygos/hemiazygos veins, indicating an expanded hemiazygos system as the primary drainage system.

Imaging plays a critical role in the detection of this type of vascular abnormality. Herein, CT helped differentiate all vessels, discover variants, and increase the azygos system. The imaging options for studying the vascular abnormality include echocardiographic techniques and color Doppler.

Imaging, CT angiography, and IVC angiography can detect hypoplastic/interrupted IVC, identify abnormal vessels, and assess azygos system dilatation due to increased flow. Angiography is useful for determining the precise anatomy of vessel drainage for surgical purposes. Detecting venous abnormalities is crucial because they can interfere with right heart catheterization, cardiopulmonary bypass surgery, and pacemaker insertion. IVC hypoplasia, or interrupted IVC in extreme cases, also known as azygos–hemiazygos continuation, is a benign disorder that does not require treatment owing to adequate vascularization [10-11].

However, patient knowledge is critical in the event of surgical intervention [9-14]. A misdiagnosis mayoccurr because of possible mediastinal shadow enlargement on chest X-ray images or dilated azygos or hemiazygos vein adjacent to the descending aorta on transesophageal echocardiography mimicking aortic pathology [5, 10, 12].

Interrupted IVC is often linked to other congenital defects, particularly in the cardiac region, prompting a search for related conditions. The presence of other pathologies must be evaluated. Excluding portosystemic shunting is crucial for management because chronic congenital portosystemic shunts can lead to serious complications. The presented case did not correlate with other congenital defects or the patient’s malignancy. Both situations can be regarded as independent.

Conclusion

This report presents an uncommon venous abnormality in the chest and abdomen of an asymptomatic adult with hypoplastic IVC accompanied by azygos/hemiazygos hypertropia and the presence of numerous collateral venous circles. This case highlights the importance of imaging in the detection of complex vascular abnormalities. Physicians should carefully examine this unique vascular abnormality to prevent misdiagnosis and improve surgical outcomes.

Additional information

Funding source. This article was not supported by any external sources of funding.

Competing interests. The authors declare that they have no competing interests.

Authors’s contribution. All authors made a substantial contribution to the conception of the work, acquisition, analysis, interpretation of data for the work, drafting and revising the work, final approval of the version to be published and agree to be accountable for all aspects of the work. M. Montatore — work conception, data collection, manuscript preparation and editing; G. Gugliemi — work conception, analysis and iterpretation of data, manuscript preparation and editing; G. Muscatella, F. Masino — work conception; R. Gifuni — data collection; M. Balbino — analysis and iterpretation of data, manuscript preparation and editing; G. Ricatti — manuscript preparation and editing.

Consent for publication. Written consent was obtained from the patient for publication of relevant medical information and all of accompanying images within the manuscript in Digital Diagnostics journal.

作者简介

Manuela Montatore

Foggia University School of Medicine

编辑信件的主要联系方式.
Email: manuela.montatore@unifg.it
ORCID iD: 0009-0002-1526-5047

MD

意大利, Foggia

Gianmichele Muscatella

Foggia University School of Medicine

Email: muscatella94@gmail.com
ORCID iD: 0009-0004-3535-5802

MD, Department of Clinical and Experimental Medicine

意大利, Foggia

Federica Masino

Foggia University School of Medicine

Email: federicamasino@gmail.com
ORCID iD: 0009-0004-4289-3289

Department of Clinical and Experimental Medicine, MD

意大利, Foggia

Giovanni Ricatti

«Monsignor Raffaele Dimiccoli» Hospital

Email: g.ricatti@live.com
ORCID iD: 0009-0006-7620-1011

MD

意大利, Barletta

Marina Balbino

Foggia University School of Medicine

Email: marinabalbino93@gmail.com
ORCID iD: 0009-0009-2808-5708

MD, Department of Clinical and Experimental Medicine

意大利, Foggia

Rossella Gifuni

Foggia University School of Medicine

Email: rossella.gifuni@unifg.it
ORCID iD: 0009-0009-9679-3861

MD, Department of Clinical and Experimental Medicine

意大利, Foggia

Giuseppe Guglielmi

Foggia University School of Medicine; «Monsignor Raffaele Dimiccoli» Hospital; IRCCS Casa Sollievo della Sofferenza Hospital

Email: giuseppe.guglielmi@unifg.it
ORCID iD: 0000-0002-4325-8330

MD, Professor, Department of Clinical and Experimental Medicine

意大利, Foggia; Barletta; Giovanni Rotondo

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