Right-to-left shunting via persistent left superior vena cava identified by perfusion lung scintigraphy

A right-to-left shunt was demonstrated following a left antecubital injection of [99mTc]MAA but was not seen after a right antecubital injection. This was because of the presence of a persistent left superior vena cava draining into the left atrium. Recognition of the presence of this anatomic variant is of importance in perfusion imaging, in patients with otherwise unexplained systemic embolization.     

Duplication of the superior vena cava: Detection by radionuclide angiography

The authors report three cases of duplication of the superior vena cava which were demonstrated by radionuclide angiography. Nuclear imaging was performed in order to demonstrate a left-to-right intracardiac shunt. Injection into the left external jugular vein demonstrated the presence of a duplication of the superior vena cava in addition to the presence of a shunt.     

Capillary anastomosis in vena caval thrombosis

A 29-year-old woman presented with recurrent diffuse histiocytic lymphoma. Bilateral brachial venous catheters were placed for chemotherapy, which resulted in thrombotic occlusion of the superior vena cava. A lung scan with Tc-99m MAA (flow study and static images) demonstrated extensive collateral vessels in the upper thorax and trapping of particles in the right upper abdomen, anteriorly. A simultaneous liver scan with Tc-99m sulfur colloid (flow and delayed images) illustrated a normal liver with no other abnormal sites of tracer deposition. The accumulation of a lung imaging agent in the anterior abdominal wall was secondary to capillary anastomosis between the superior and inferior epigastric veins.     

Duplication of the superior vena cava: detection by radionuclide angiography

The authors report three cases of duplication of the superior vena cava which were demonstrated by radionuclide angiography. Nuclear imaging was performed in order to demonstrate a left-to-right intracardiac shunt. Injection into the left external jugular vein demonstrated the presence of a duplication of the superior vena cava in addition to the presence of a shunt.     

Systemic to pulmonary venous shunt in lung cancer with obstruction of superior vena cava: case report with review of the literature

We describe the CT features of an unusual collateral pathway of systemic to pulmonary venous shunt in a patient with lung cancer that obstructed the superior vena cava (SVC). Spiral CT scan with rapid injection of contrast medium from a right arm vein revealed a systemic to pulmonary venous shunt (SPVS), passing through thick pleural effusion, which was the direct transpleural communication between right upper chest wall veins and right superior pulmonary veins. Three-dimensional CT angiography revealed the entire shunt. We consider that the shunt was formed in association with radiation therapy, and was not injured with the subsequent collapse of the lung and accumulation of massive pleural effusion. We review the reports that have dealt with the shunt in patients with lung cancer, and discuss the conditions related to the development of SPVS in such patients.     

Shunt between right subclavian vein and the left heart in superior vena cava obstruction due to lung cancer

A case in which there was a shunt between systemic veins and the left heart in superior vena cava syndrome due to lung cancer is reported. Superior vena cava syndrome developed one and a half years after right upper lobectomy with combined resection of thoracic wall. Radionuclide venography from the right antecubital vein showed immediate visualization of the left ventricle and aorta, before the right atrium and right ventricle were seen. In the superior vena cava syndrome due to a malignant tumor, this rare pathway as well as usual collaterals should be considered.     

Scintigraphic assessment of pulmonary and whole-body blood flow patterns after surgical intervention in congenital heart disease.

Glenn shunt and Fontan procedure, the most widely used surgical procedures in congenital heart anomalies, may be associated with abnormal pulmonary blood flow patterns and the development of pulmonary arteriovenous fistulae. METHODS: This study quantified pulmonary and whole-body blood flow using the microsphere technique by sequential injection of 99mTc microspheres into upper and lower limb veins and performing planar lung imaging in four projections and anterior and posterior whole-body scans in 46 patients with either Glenn shunt or Fontan procedure. The right-to-left shunt volume was estimated by a brain and kidneys-to-lungs ratio and compared with calculations from the whole-body scans. RESULTS: In 31 of 46 patients, the blood from the superior vena cava was drained preferentially into the right lung (75%+/-19%). The inferior venous system was drained equally into both lungs. The right-to-left shunt volume was 24%+/-12% after injection into the superior caval system, 50%+/-18% after injection into the inferior caval system. A subgroup of patients who had undergone a palliative Blalock-Taussig shunt (BTS) before the final surgery showed a perfusion pattern that was not known after pulmonary angiography or contrast echocardiography: 15 of 24 patients with BTS had hypoperfusion of the upper lobe on the side of the BTS after injection into the arm vein and corresponding normal perfusion or hyperperfusion when injected into the foot vein. CONCLUSION: Lung perfusion scintigraphy after tracer application into the superior and inferior caval systems detects more abnormal pulmonary blood flow patterns than contrast echocardiography and is the only procedure able to quantify right-to-left shunt volume individually for the superior and inferior caval systems. Thus, this diagnostic technique should be part of the routine follow-up in children after Glenn shunt or Fontan procedure.     

Systemic-to-pulmonary venous shunt in superior vena cava obstruction: depiction on computed tomography venography

Purpose: To describe computed tomography (CT) venographic appearances of systemic-to-pulmonary venous shunts with CT venography and three-dimensional reconstruction images from patients with superior vena cava obstruction.

Material and Methods: From January 1994 to April 2002, CT venography was performed in 45 patients with superior vena cava obstruction using a single-detector helical CT scanner (n=38) and four-detector row CT scanner (n=7). Analysis of CT scan data included the cause and degree of venous obstruction, the presence of pleural thickening and enhancement, and the attenuation of pulmonary veins. The causative factor for systemic-to-pulmonary venous shunt was evaluated using the Fisher exact test.

Results: Systemic-to-pulmonary venous shunts were observed in four patients (9%) who had high-attenuated pulmonary veins and pleural enhancement on CT venography. Pleural thickening (P=0.01) and a history of pulmonary tuberculosis (P=0.034) are statistically significant risk factors.

Conclusion: CT venography showed strong pleural enhancement and high-attenuated pulmonary veins indicating systemic-to-pulmonary venous shunts. Radiologists should study the earlier enhancement of pulmonary veins in patients with superior vena cava obstruction.     

Demonstration of persistent left superior vena cava by first pass radionuclide angiography

A case of the left superior vena cava draining to the coronary sinus without associated intracardiac shunt was initially demonstrated by first pass radionuclide angiography. The patient had atypical chest pain for 8 years, and had sick sinus syndrome with a long cardiac pause. Cardiac catheterization confirmed this diagnosis, and a transvenous pacemaker was successfully implanted through the left superior vena cava.     

Combined superior vena cava and pulmonary artery obstruction by an ascending aortic aneurysm

A case report is presented on the use of intravenous radioisotope angiocardiography in the diagnosis of an atherosclerotic aneurysm of the ascending aorta in a 44-year-old man who presented with mild superior vena cava obstruction. In addition to outlining the site and extent of the aneurysm, intravenous Tc-99m-albumin radioisotope angiocardiography and blood pool imaging permitted demonstration of the site of obstruction of the cava, indicated the presence of venous collateral channels bringing about delayed filling of the right heart, and also detected obstruction of the right pulmonary artery by the aneurysm. The procedure is simple, rapid, and entirely noninvasive and permits both anatomic and hemodynamic evaluation of the abnormality.     

Collateral pathways in superior vena caval obstruction as seen on gamma images

The collateral pathways, known from contrast studies to take over the drainage of blood from the various parts of the body when the superior vena cava or its major tributaries are occluded because of disease, can easily be demonstrated with equal clarity (except for the vertebral plexus pathway) by radionuclides. The failure to delineate the vertebral plexus pathway is felt to lie in the close anatomical relationship between the vertebral plexus and the vertebrae, which cause attenuation of the emerging photons. Because of the existing anastomotic channels and their anatomical direction, location and distribution of the individual collateral pathways are individually identifiable. The site/level, extent, degree, and probable duration of occlusion directly affect the degree and extent of the collaterals that subsequently develop. In 20 of 49 abnormal radionuclide superior venacavograms, incidental but abnormal imaging features not ascribable to caval obstruction or syndrome were noted. These included persistent left superior vena cava, aortic aneurysm, pericardial effusion, and disparity in pulmonary perfusion.     

Periumbilical uptake of Tc-99m MAA on lung perfusion scanning in a patient with superior vena cava obstruction

A 25-year-old woman with severe parenchymal lung disease of unknown etiology and existing for more than a decade was referred for ventilation-perfusion scintigraphy because of suspicion of pulmonary embolism. Both ventilation and perfusion images showed, apart from perfusion defects from her severe lung disease, a left apical pneumothorax and signs of recurrent pneumonia of the left lower lobe. Noteworthy was the periumbilical uptake of the Tc-99m macroaggregated albumin (MAA). Her medical history revealed iatrogenic superior vena cava (SVC) obstruction. In this case, the main collateral pathway of portosystemic shunting is probably, after recanalization of the left umbilical vein, a network of smaller paraumbilical veins.     

Persistent left superior vena cava detected with radionuclide angiocardiography

A 28-year-old man presented with paresthesias, fatigue, central cyanosis, and erythrocytosis. A first pass flow study with Tc-99m as free pertechnetate was done, among other tests, to exclude a central shunt when a persistent left superior vena cava was incidentally detected. The value of radionuclide angiocardiography to examine the central circulation noninvasively was again illustrated in this case.     

先天性心脏病合并右上腔静脉缺如及永存左上腔静脉畸形的治疗

目的 探讨先天性心脏病合并右上腔静脉缺如及永存左上腔静脉畸形的治疗方法。方法 手术治疗2例,在全麻体外循环下行矫治术。1例采用左上腔静脉直接插管法,1例采用心内冠状静脉窦插管法。结果 2例均治愈,远期无心律失常发生。结论 先天性心脏病中,左上腔静脉合并右上腔静脉缺如非常少见,认识不足,是造成漏诊的主要原因。术中应根据情况酌情处理,但无论采取哪种方法,一定要注意对冠状静脉窦口的保护及左上腔静脉引流的通畅。     

Reversed intrapulmonary right-to-left shunt after banding of the patent ductus venosus

Diffuse pulmonary microvascular arteriovenous communication developed in an 8-year-old girl with a patent ductus venosus. Tc-99m macroaggregated albumin (MAA) pulmonary perfusion scintigraphy with total-body imaging demonstrated multiple lung perfusion deficits and abnormal tracer uptake in systemic organs with hepatic radioactivity greater than the kidneys, suggesting the presence of right-to-left shunt and abnormal hepatic hemodynamics. I-123 iodoamphetamine transrectal portal scintigraphy revealed a large portosystemic venous shunt. The follow-up Tc-99m MAA perfusion scans after banding of the patent ductus venosus revealed partial improvement of the perfusion deficits and right-to-left shunt, indicating the possible reversibility of this pulmonary shunt complication.     

Systemic to pulmonary venous communication (right-to-left shunt) in superior vena cava obstruction demonstrated by spiral CT

An unusual case of systemic vein to pulmonary vein communication in superior vena cava obstruction is reported. This was a right-to-left shunt, demonstrated by spiral CT and aided by three-dimensional reconstruction. The pulmonary venous shunts were mainly seen in fibro-atelectatic lung where prominent bridging veins were concentrated.     

Scintigraphic evaluation of small pulmonary right-to-left shunt and therapeutic effect in pulmonary arteriovenous malformation

PURPOSE: Right-to-left shunts of pulmonary arteriovenous malformation (PAVM) can be detected and measured by pulmonary perfusion scans using Tc-99m MAA. In PAVM with a relatively small right-to-left shunt, however, measurement of the shunt ratio may not be reliable. This study re-evaluated pulmonary perfusion scans for a small right-to-left shunt of PAVM. METHODS: Tc-99m MAA lung scans were performed in five patients with proved PAVM before and after percutaneous transcatheter embolization. The right-to-left shunt ratio was calculated and extrapulmonary uptake was assessed on total-body images. RESULTS: Lung perfusion scans obtained before embolization revealed brain uptake in four patients, and the shunt ratio ranged from 4.4% to 22.9%. In two patients with a small single PAVM, the shunt ratio was less than 15% before treatment and did not change significantly after successful embolotherapy. The brain uptake, which had been clearly visible before therapy, disappeared after embolization. Renal uptake was seen on pre- and post-therapy scans. CONCLUSIONS: Changes in brain activity visible on Tc-99m MAA scans might be a more reliable sign than a decreased shunt ratio or a change in renal uptake when evaluating embolization therapy in patients with PAVM who have a small right-to-left shunt.     

Effect of neck position during radionuclide superior cavography. Its value in the diagnosis of superior vena cava obstruction due to retrosternal goiter

In five patients with substernal goiter, three of whom presented with superior vena cava (SVC) syndrome, and in five normal subjects, radionuclide superior cavography (RNSC) was performed with extension and flexion of the neck during tracer administration (simultaneous bilateral injection of Tc-99m pertechnetate). When the tracer was injected during neck extension, venous flow pattern was abnormal in four of five patients, and transit time (TT) prolonged in three of five patients. In this posture, mean TT +/- 1 standard deviation (SD) was 6.3 +/- 2.6 s (range 3.5 to 9 s) for the five patients and 3.5 +/- 0.7 s (range 2.5 to 4.5 s) for a group of five control subjects. When the tracer was injected during neck flexion, all five patients showed abnormal flow patterns and prolonged TT (mean +/- 1 SD 10.1 +/- 4.1 s; range 4.4 to 16 s), in contrast to the control group where a slight decrease in TT was found (mean +/- 1 SD 3 +/- 0.6 s; range 2 to 3.5 s). In the presence of a substernal goiter, or any mobile mass at the thoracic inlet, impairment of venous flow through the SVC system appears to be a common occurrence, readily detectable by RNSC. RNSC should be performed with neck flexion during tracer injection, since in this posture its ability to detect compromised venous flow through the SVC system is enhanced, even in patients without a clinically apparent SVC syndrome.     

Unusual variant of left superior vena cava

The first computed tomography-documented case of a persistent left superior vena cava that drains directly into the right superior vena cava is presented. The venous embryology is reviewed and the differential diagnosis of other pertinent venous anomalies is discussed. The patient also had an incidental finding of a congenitally absent left lobe of the thyroid gland.     

Congenital left superior vena cava with absent right superior vena cava: a cause of progressive mediastinal widening

We wish to report a patient with the rare anomaly of congenital left superior vena cava and absent right superior vena cava. This became apparent on chest radiographs by the development of a left mediastinal "mass" over a one-year period. The role of contrast-enhanced computed tomographic scanning in the detection of venous anomalies is stressed.