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Corresponding author at: Technical University of Dresden, University Hospital Carl Gustav Carus, Department of Pneumology, Fetscherstr. 74, 01304 Dresden
In clinical routine, the pulmonary contrast-enhanced chest computer tomography (CT) is usually focussed on the pulmonary arteries. The purpose of this pictorial essay is to raise the clinicians’ awareness for the clinical relevance of CT pulmonary venography.
Case Presentation
A pictorial case series illustrates the clinical consequences of different pulmonary venous pathologies on systemic, pulmonary and bronchial circulation.
Conclusion
Computed tomography pulmonary venography must be considered before atrial septal defect (ASD) closure and pulmonary lobectomy. Computed tomography pulmonary venography should be considered for patients with right ventricular overload and pulmonary hypertension, as well as for patients with unclear recurrent pulmonary infections, progressive dyspnoea, pleural effusions, haemoptysis, and for patients with respiratory distress after lung-transplantation.
The aim of this pictorial essay is to illustrate the clinical relevance of CT pulmonary venography. Because symptoms and signs of pulmonary venous pathologies are profoundly unspecific, findings in the affected patients are likely to be misleading if attention is not paid to the pulmonary veins. The most common pathologies of the pulmonary veins are congenital partial anomalous pulmonary venous return (PAPVR) and pulmonary venous stenosis (PVS).
Congenital partial anomalous pulmonary venous return is estimated to be prevalent in about 0.5% of the general population and increases up to 20-30% in patients with atrial septal defects. The relatively high prevalence is attributed to the complex development of the pulmonary veins arising from the primordial foregut in about the sixth week of gestation. Partial anomalous pulmonary venous return can stand either isolated, or be associated with other congenital heart diseases, most likely with a superior sinus venosus defect [
]. The anomalous pulmonary drainage results in a systemic-to-pulmonary shunt with chronic right ventricular volume overload. Shunt magnitude depends on the pressure gradients between the systemic and pulmonary circulation and on the expanse of the anomalous drainage. Although the majority of PAPVR-patients are clinically nondescript in the early stages, some patients will develop exertional dyspnoea due to overflow-induced pulmonary arterial hypertension (PAH-CHD), and some patients will even develop progressive right-heart failure. Isolated PAPVR presents a different clinical course to PAPVR with an atrial septal defect (ASD), or with a sinus venosus defect (SVD). Patients with isolated PAPVR have an isolated systemic-to-pulmonary shunt; in contrast, when pulmonary arterial pressure exceeds the systemic arterial pressure, patients with associated ASD or SVD will develop shunt-reversal with pulmonary-to-systemic shunt (Eisenmenger reaction).
Time of clinical manifestation is typically between 20-40 years, predominantly with exertional dyspnoea. Transthoracic echocardiography initially shows right ventricle dilation. In the long term, some patients develop tricuspid regurgitation and pulmonary hypertension. Chest X-ray shows signs of pulmonary overflow in the early stages, but later in the course the lung vessels are reduced and the hilar pulmonary arteries are dilated. Right-heart-catheterisation (RHC) typically detects increased cardiac output of the right ventricle due to the shunt volume. With stepwise oxymetry significant oxygen-jumps can be detected at the PAPVR orifice into the systemic venous circulation. Yet with RHC and oxymetry precise shunt localisation is elusive, because shunt volume depends on pressure gradients and on the ejection fraction. Shunt detection of sub-diaphragmatic PAPVR is very difficult and often missed. Because of the high coincidence of PAPVR with ASD and SVD, CT pulmonary venography must be considered prior to ASD or SVD occlusion. If PAPVR is missed, continuing systemic-to-pulmonary shunt will thwart the therapeutic success of the supposed surgical/interventional shunt correction. Unfavourably severe PAH-CHD can develop later in life. Paroxysmal supraventricular tachyarrhythmias (pSVT) are also a typical clinical manifestation of PAPVR. This is why in young patients with pSVT a CT pulmonary venography should be contemplated before an electrophysiology study is performed. Figure 1 illustrates A) normal pulmonary venous return, B) isolated partial anomalous pulmonary venous return, and C) PAPVR in combination with an ASD in the early clinical course with left-to-right shunt – D) as well as in the late clinical course with shunt reversal and right-to-left shunt.
B: Isolated anomalous pulmonary venous return with merely systemic-to-pulmonary shunt.
C: Partial anomalous pulmonary venous return associated with an atrial septal defect, in the early clinical course with primarily systemic-to-pulmonary shunt.
D: Shunt reversal with pulmonary-to-systemic shunt in the late clinical course.
If diagnosis of PAPVR is missed, the images of Figure 2 (Patient 1) and Figure 3 (Patient 2) exemplify the clinical consequences of interventional ASD-closure with an occlude device and continuing left-to-right shunt. An ASD was closed in both patients with an Amplatzer-device many years before the patients presented with progressive dyspnoea. The continuing shunt volume resulted in progressive pulmonary hypertension and right-heart failure in both patients. Pulmonary CT-venography unmasked PAPVR non-invasively and precisely within a few minutes. In Patient 1 almost the complete left lung and part of the right lower lobe drained anomalously into the systemic venous circulation. Almost the complete left lung drained via a vertical vein into the left brachiocephalic vein and part of the right lower lobe drained into the inferior vena cava. These anomalies were missed in three previous contrast-enhanced chest CTs, which all were performed without pulmonary venography. In Patient 2 almost the complete right lung drained anomalously into the superior vena cava. The continuing systemic-to-pulmonary shunt resulted in progressive right-heart failure despite interventional ASD-closure years ago. Patient 3 (Figure 4) presented with exertional dyspnoea NYHA II and moderate right heart dilation was found with transthoracic echocardiography. With RHC increased cardiac output with mild pulmonary arterial hypertension and an oxygen jump was detected. Computed tomography pulmonary venography facilated the diagnosis of PAPVR of the left upper pulmonary lobe.
Figure 251-year-old woman with progressive dyspnoea NYHA III and severe right ventricular overload 20 years after an interventional ASD-closure. PAPVR had been overlooked in three previous chest CTs without venography.
A: Anterior view: on the left side, there is a large vena verticalis (**) and on the right side, there is a small accessory right lower pulmonary vein (*) draining into the inferior vena cava.
B: Left anterior oblique (LAO) view disclosed PAPVR of the left upper (***) and the left lower pulmonary vein (****) via a vertical vein (**) into the left brachiocephalic vein.
C: Right (*) and left (**) atrium with the occluder device (***).
D: Vertical vein (white arrow) with pulmonary venous drainage of the left lung into the left brachiocephalic vein. Noteworthy, this is not a persistent left-sided vena cava (PLSVC), because PLSVC drains blood from the left brachiocephalic vein via the oblique vein (vein of Marshall) into the coronary sinus.
Figure 362-year-old male with progressive exertional dyspnoea NYHA III and history of interventional atrial septal occlusion 15 years ago. In the right-heart catheter recording at that time, partial anomalous venous connection was explicitly excluded.
Figure 468-year-old man with progressive dyspnoea NYHA II due to isolated partial anomalous pulmonary venous return of the left upper pulmonary vein and pulmonary venous drainage via a vertical vein into the left subclavian vein.
A: Axial CT images show the anomalous vertical vein (white arrow)
B: Drainage of the mid and upper left pulmonary veins into the vertical vein (white arrow)
C: The volume rendering (VRT) image shows veins from the left upper lobe that are draining into the left brachiocephalic vein. The white arrow highlights a left vertical vein which is draining blood from the left lung into the brachiocephalic vein.
Figure 5 shows variants of PAPVR and TAPVR with shunt bloodflow to illustrate the difficulty of precise shunt diagnosis with RHC and stepwise oximetry.
Figure 5Schematic illustration of shunt bloodflow for the different variants of PAPVR/TAPVR described by Snellen et al. (1) This illustration shows the difficulty of precise shunt diagnosis with right heart catheterisation and stepwise oxymetry.
Pulmonary venous stenosis (PVS) is another relatively common pathology of the pulmonary veins. The precise prevalence of pulmonary venous stenosis is unknown as there are many acquired and congenital causes for PVS [
]. Common radiological findings are thickened interseptal lines, ground-glass opacity, enlarged hilar lymph nodes and pleural effusions. As a result of regional differences in pulmonary vascular resistance, the pulmonary blood flow redirects towards regions with lower vascular resistance [
]. This is why CT pulmonary venography should be considered in the differential diagnosis of scintigraphic pulmonary perfusion deficits.
Figure 6, Figure 7, Figure 8, Figure 9, Figure 10 illustrate different causes of pulmonary venous obstruction in patients with progressive dyspnoea NYHA II-IV. Figure 6: 52-year-old man (NYHA II) with congenital pulmonary venous atresia of the right lung, resulting in hypoplasia of the right skeletal hemithorax, pulmonary artery and the right lung. Pulmonary perfusion scintigraphy detected a complete perfusion shift towards the left lung. Extensive pleuro-hilar bronchial collateral veins drain the right bronchial circulation into the superior and inferior vena cava. Figure 7: 51-year-old woman (NYHA III) with surgical corrected PAPVR at the age of 17. Due to baffle occlusion the patient suffered from recurrent pneumonias in the long term. Increased pulmonary venous resistance in the right lung resulted in a perfusion shift towards the left lung. Due to the chronic pulmonary congestion right-sided pleura and interlobular septal lines were thickened. Figure 8: 78-year-old woman with NYHA IV and haemoptysis after pulmonary vein isolation for therapy of atrial fibrillation. Figure 9: 72-year-old man with dyspnoea NYHA III and recurrent left sided pleural effusion due to thrombosis of the left lower pulmonary vein one month following pulmonary vein isolation (PVI). Figure 10: 63-year-old woman with progressive dyspnoea NYHA III and haemoptysis six months after interventional isolation of the pulmonary veins for therapy of atrial fibrillation.
Figure 652-year-old man with exertional dyspnoea NYHA II, paroxysmal atrial fibrillation and clinically only mild thoracic asymmetry.
A: Hypoplasia of the right hemithorax, right lung and right-sided pulmonary arteries (**).
B: Congenital atresia of the right-sided pulmonary veins (*).
C: Perfusion scintigraphy discloses functional single lung (***, anterior view).
D: In the right hemithorax, extensive pleuro-hilar bronchial venous collaterals (white arrow) drain the right bronchial circulation into the vena cava. Right pulmonary venous atresia (*) and right pulmonary arterial hypoplasia (**).
Figure 751-year-old woman with dyspnoea NYHA III. Surgical correction of right-sided partial anomalous pulmonary venous return with a graft + baffle at the age of 17. Years after the surgical correction, the patient suffered from recurrent pneumonia.
B: Posterior view: absent right pulmonary veins (*). PAPVR left upper lobe into the superior vena cava (**) and pulmonary veins mainly from the left lower lobe (***)
C: Calcified surgical graft (white arrow)
D: Perfusion scintigraphy (posterior view) disclosed almost absent perfusion of the right lung (****) in combination with a perfusion deficit of the left upper lobe. Perfusion mainly of the left lower lobe.
Figure 878-year-old woman with progressive dyspnoea NYHA IV following interventional isolation of the pulmonary veins for therapy of atrial fibrillation.
A: Posterior view: pulmonary arterial and venous vessels before pulmonary vein isolation (PVI).
B: Pulmonary veins and arteries after PVI.
C: Posterior view: multiple severe pulmonary venous stenosis with near-total occlusion of the upper and lower left (*) and right upper (**) pulmonary vein. Only the right inferior pulmonary vein remained unobstructed.
D: Pulmonary perfusion scintigraphy (anterior view) disclosed severe perfusion deficits of the entire left lung and the right upper lobe.
Figure 972-year-old man with dyspnoea NYHA III and recurrent left sided pleural effusion due to thrombosis of the left lower pulmonary vein one month following pulmonary vein isolation (PVI).
B: Axial contrast-enhanced CT image shows thrombosis of the left lower lobe vein (black arrow) and left sided pleural effusion (**)
C: 3D reconstruction of the left atrium, the pulmonary arteries and the central pulmonary veins with imaging of the veno-atrial junctions. Missing of the left lower pulmonary vein (***)
D: Pulmonary perfusion scintigraphy with severe perfusion deficit of the left lower lobe and lingula (***).
Figure 1063-year-old woman with progressive dyspnoea NYHA III and haemoptysis six months after interventional isolation of the pulmonary veins for therapy of atrial fibrillation.
These images demonstrate that CT pulmonary venography must be considered before interventional and surgical ASD closure. Computed tomography pulmonary venography must also be considered before pulmonary lobectomy to avoid unfavourable respiratory distress postoperatively [
]. Postoperative adverse pulmonary venous stenosis may, for example, result in the case of inferior lobectomy and drainage of the right middle lobe vein into the right inferior pulmonary vein. Computed tomography pulmonary venography should be considered in patients with right ventricular overload and pulmonary hypertension, as well as in patients with recurrent pulmonary infections, recurrent pleural effusions, haemoptysis, unclear progressive dyspnoea, and for patients with respiratory distress after lung-transplantation [
]. Differentiation between pulmonary arterial and pulmonary venous causes of perfusion deficits in the scintigraphic perfusion scan is almost impossible. In the affected patients, CT pulmonary venography may cut the diagnostic Gordian knot quickly, precisely and non-invasively. If a pulmonary venous pathology is diagnosed, the therapeutic procedures probably will be changed. Figure 5 illustrates the difficulty of precise shunt diagnosis with right heart catheterisation in case of PAPVR. To diagnose sub-diaphragmatic PAPVR shunt, widening of the CT-angiography window towards the upper abdomen should be contemplated in selected cases with unclear right ventricular overload.
Pulmonary venous stenosis mimics pulmonary diseases and is associated with potentially life-threatening complications, which is why prompt diagnosis is paramount. Other diagnostic methods than CT pulmonary venography like transoesophageal echocardiography, MRI venography or direct venography, are either considerably less sensitive or are not useful for visualising the subsequent parenchymal pathologies in the affected lungs [
A comparison of pulmonary vein ostial anatomy by computerized tomography, echocardiography, and venography in patients with atrial fibrillation having radiofrequency catheter ablation.
]. Today, computed tomography angiography (CTA) is the method of choice for imaging of the pulmonary vessels. Computed tomography utilises ionising radiation to produce three-dimensional datasets of the examined anatomic region. With this method, injection of iodinated contrast media in a peripheral vein is necessary in order to visualise blood vessels. The delay between the contrast injection and the beginning of the scan determines which vessels contain more contrast and are thus better visible on the resulting images. Currently, the so-called bolus tracking technique is used to trigger the start of the CTA acquisition. A circular region of interest (ROI) is placed in a predefined vessel (the left atrium, if both pulmonary veins and arteries are to be visualised) using vendor-provided software and repeated low dose CT scans are acquired at the same level. When the trigger threshold is reached, the patient table is automatically moved to the start position and the CTA is acquired in breathhold. All the present angiographic CT-images were generated with the ROI in the left atrium resulting in a simultaneous pulmonary arterio- and venography. Three dimensional reconstruction was extremely helpful to visualise the pulmonary venous pathologies. Furthermore, 3D reconstruction with volume rendering technique (VRT) facilitates the decision whether an anomalous para-aortic vessel must be diagnosed as a persistant left vena cava with drainage from the left brachiocephalic vein into the coronary sinus, or if it must be diagnosed as an anomalous pulmonary venous drainage with bloodflow from the lungs into the left brachiocephalic vein.
The authors declare that there are no conflicts of interest regarding this manuscript.
A comparison of pulmonary vein ostial anatomy by computerized tomography, echocardiography, and venography in patients with atrial fibrillation having radiofrequency catheter ablation.
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