case_images: PMC11770387_01
case_images: Initial 24-hour ECG revealed a number of pauses, the longest of which lasted in the region of 4.
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case_images: The 24-hour tape showed Brugada type 2 and sinus pauses up to 4  (Figure 1).
case_images: Composite echocardiographic images. Two-dimensional echo picture of brachiocephalic vein and connecting levo-atrial cardinal vein imaged from suprasternal view (A). Colour flow mapping indicates downstream flow from the levo-atrial cardinal vein towards the left atrium (B). Contrast echocardiography via left arm (C) demonstrated the right-to-left shunt from brachiocephalic vein into the left atrium. Endocardial ventricular pacing lead was seen within the right atrium and right ventricle (asterisk). Later, follow-up two-dimensional echocardiogram with colour follow mapping (D) performed after endocardial pacing system removal revealed obstruction of the superior caval vein at the level of cavo-atrial junction. LACV, levo-atrial cardinal vein; AO arch, aortic arch; LA, left atrium; RPA, right pulmonary artery.
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case_images: The patient was referred for a detailed echocardiogram including contrast, this demonstrated a right-to-left shunt from the innominate vein to the LA (Figure 2).
case_images: Composite computed tomography angiogram. The dedicated cardiovascular computed tomography (A) confirmed the presence of the levo-atrio cardinal vein (arrow 1), connecting the bridging vein to the left atrium via the left upper pulmonary veins. The computed tomography (B) also demonstrated hold up of contrast medium at the level of the superior caval vein to right atrium junction stenosis (circled), with contrast held up and delayed in the passage from the dilated superior caval vein (asterisk 1) into the right atrium (asterisk 2) and seeking into paravertebral collaterals and down the azygos vein (arrow 2). The pacing wire is seen in situ, running through the superior caval vein into the right atrium (arrow 3). A subsequent cardiovascular computed tomography (C, D) showed the banded levo-atrio cardinal vein (arrow 4). LACV, levo-atrial cardinal vein.
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case_images: A subsequent cardiovascular CT angiogram confirmed right SVC obstruction with an innominate vein to the LUPV venous channel and right to left shunt (Figure 3).
case_images: Composite X-ray cardiac angiogram in lateral (A) and antero-posterior (B) projection confirmed significant narrowing of the right superior caval vein at the level of the cavo-atrial junction. Angiogram after balloon angioplasty in lateral (C) and antero-posterior (D) projection confirmed successful dilatation with marked calibre change as compared with pre-procedural angiogram.
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case_images: Six-month follow-up of the patient found residual obstruction to SVC flow with elevated central venous pressure and the patient underwent transcatheter balloon dilation of the stenosis at the junction of the right SVC and RA (Figure 4).