Chest: Pericardial Varices: Depiction by 3DCT Angiography

Leo P. Lawler, M.D.1

Elliot K. Fishman, M.D., FACR1

Introduction

The pericardial veins, which make up part of the deep venous drainage of the thorax, are rarely mentioned in the literature and their anatomic description by imaging has been largely limited to documentation of misplaced central venous catheters. A patient with occlusive, bland thrombus in the superior vena cava, azygos and the left brachiocephalic provided a unique opportunity for multidetector CT (MDCT) and three-dimensional (3D) volume rendering to create a vascular map of these and other deep veins of the thorax.

Case Report

A 25 year-old woman presented to the emergency room after a two-week history of progressive pain and swelling of the right arm and the recent onset of face swelling. The patient had a history of asthma and immunoglobulin deficiency for which she was on chronic steroid and methotrexate therapy. She had a non-functioning right subclavian porta-catheter with its tip in a right superior vena cava. A thoracic CT was ordered. On a Siemens Plus 4 Volume Zoom multidetector CT scanner (Siemens Medical Systems, Iselin, NJ) a contrast-enhanced thoracic CT was performed. The patient was imaged with 3mm collimation and a 2.5 detector of the adaptive array using 2mm data reconstruction and a pitch of 6. 120cc of Omnipaque 350 (Nycomed Amersham, Princeton, NJ) was given at a rate of 3cc/sec with a scan delay of 40 seconds. Three-dimensional volume rendering was subsequently performed on a prototype Siemens 3D Virtuoso workstation (Siemens Medical Systems, Iselin, NJ).

The axial images revealed occlusive thrombus in the superior vena cava, the azygos and left brachiocephalic veins (Fig. 1A). There were multiple small foci of high attenuation, similar to that of the intravenous contrast, intimately adjacent to the outer surface of the fibrous pericardium as well as in the superior mediastinum (Figs. 1A and 1B). An image at the level of the upper liver showed a hyper-enhancing quadrate lobe, opacified azygos, hemiazygos and left inferior phrenic veins and a trans-hepatic collateral vein.

Three-dimensional volume rendering showed these focal areas of contrast to represent extensive pericardial varices and other venous collaterals (Fig. 1C). The multiple projections of the volume rendered images enabled thorough anatomic delineation of these multiple tortuous veins. Two left pericardiophrenic veins were identified extending between the left medial brachiocephalic vein and the left inferior phrenic vein (Fig. 1D). A single right pericardiophrenic vein ran superiorly from the right inferior phrenic vein and was shunted to unnamed inter-brachiocephalic and thymic collateral veins and away from the occluded superior vena cava. (Fig. 1E). A continuous arcade was formed from the left pericardiophrenic veins to the left inferior phrenic veins, across to the inferior vena cava, anterior through trans-hepatic collaterals to the quadrate lobe and then connections from here to the right pericardiophenic veins and the right inferior phrenic veins (Fig. 1F).

A large left internal thoracic vein entered the left brachiocephalic vein and a smaller right internal thoracic vein was diverted from the thrombosed superior vena cava into a large thymic venous arcade (Fig. 1C). The left superior intercostal vein filled patent accessory hemiazygos and hemiazygos veins (Fig. 1D).

The patient was diagnosed with a coagulopathy of unknown origin, her right-sided porta catheter was removed and she was put on life-long anticoagulation.

Discussion

In superior vena cava obstruction the major routes of collateral circulation for venous return can be arbitrarily divided into superficial and deep systems [1], which communicate with each other. The superficial veins of the thorax and abdomen include the thoraco-epigastric veins and the intercostal veins. The deep division is largely composed of the azygos/hemiazygos, internal thoracic and lateral thoracic veins as well as the vertebral venous plexus. Among other collateral branches systemic to portal and systemic to pulmonary venous connections have also been described. The veins centered in the mediastinum are divided into anterior, posterior and pericardiac groups. Although some of these collaterals may be seen in a normal contrast-enhanced CT they become increasingly conspicuous with systemic venous obstruction [2]. The normal parietal pericardium does have small arteries and veins on its outer surface but it is not a very vascular organ unlike the visceral pericardium The pericardiophrenic veins are also termed the pericardiacophrenic or lateral mediastinal-phrenic veins. Rarely have the pericardiophrenic veins been described in the literature and never before has CT angiogram generated a vascular map of their course. They have been suggested on two previous axial CT reports but were not proven [3, 4]. These vessels drain the pericardium, pleura and diaphragm and they constitute a portion of the deep collateral venous drainage that develops with simultaneous occlusion of both the superior vena cava and azygos veins, as in this case [1]. They lie adjacent the phrenic nerve between the parietal pericardium and adjacent pleura. They may be single or double and superiorly are connected to the internal thoracic, left superior intercostal or the brachiocephalic veins. The ostium of the left pericardiophrenic is usually in the left brachiocephalic vein opposite the entrance of the left jugular vein while the right pericardiophrenic enters the ipsilateral brachiocephalic more proximally. Inferiorly both pericardiophrenic join the inferior phrenic veins and then branch to continue on to the inferior vena cava, hepatic vein or left renal vein [5, 6]. These veins serve as collateral channels for superior and inferior vena cava obstruction, can cause abnormal cardiac silhouettes on radiograph, are the site of catheter misplacement and can be involved by adjacent tumors and fistulae [7, 8]. The quadrate lobe hyper-enhancement is well described in superior vena cava obstruction and in our case was due to trans-hepatic collaterals and possibly pericardiophrenic and right inferior phrenic branches.

There were two reasons we were able to illustrate the deep venous collaterals in this patient. Firstly, with simultaneous occlusion of the superior vena cava, azygos and left brachiocephalic veins the patient was limited to the remaining deep veins seen here for her systemic venous return and they enlarged accordingly. Second, the multidetector CT generated high quality data sets, which then permitted the high fidelity volume rendering to produce the CT venous angiogram. The collaterals and varices, which by their nature are tortuous and travel across and through the transaxial plane, would be nearly impossible to follow completely on axial images but the multiple projections of the true volume and the various other post-processing parameters available greatly simplified matters.

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