The lymphatic drainage of the pericardial space in the dog

The purpose of this study was to characterize definitively the lymphatic drainage system of the pericardial space in the dog. The reports on this subject, based on dissection experiments and acute dye injections, remain controversial, and our own previous studies have been incomplete. Seventeen dogs were studied using a radiographic technique. Micropulverized barium sulfate instilled into the pericardial sac was followed with serial chest x-rays in seven dogs with intact cardiac lymphatics, in seven dogs after section of the cardiac lymphatic drainage node (the cardiac lymph node) in the right upper mediastinum, and in three dogs after resection of cardiac drainage lymphatic nodes in the left upper mediastinum. These studies revealed that the lymphatic drainage of the pericardial space is via (a) the principal coronary lymphatic which drains from the left ventricular muscle and passes to the right upper mediastinum via the cardiac lymph node, (b) the lesser coronary lymphatic which drains the right ventricular muscle and passes to the left upper mediastinum, and (c) bilateral internal mammary (parasternal) lymphatic chains. These observations are important in planning experimental approaches to the effects of impairment of lymph drainage from the pericardial space. An understanding of the lymph drainage from the pericardial space may prove significant to understanding fibrotic reactions within it and the pathologic mechanisms of such entities as constrictive pericarditis.     

Light microscopy of the lymphatics of the human atrial wall and lymphatic drainage of supraventricular pacemakers

After injection of Indian ink stained 2% gelatine in 42 human hearts the lymph drainage of the regions of supraventricular cardiac pacemakers and the patterns of the lymphatic vascular bed in the atrial wall were studied. From the sites of the pacemakers the lymph is drained into the tracheobronchial nodes in 100%. Only two of those regions are drained through additional pathways, namely the SAN region into the anterior mediastinal node situated at the azygos vein and the coronary sinus area into the anterior mediastinal lateropericardiac nodes. In the cleared specimens as microscopically the epicardial lymph vessels produce polygonal superficial network; oblique anastomoses of that network run into the deeper layers of subepicardial tissue where they join with deep irregular lymphatic network. Deep subepicardial lymph vessels are often accompanied by veins and nerves. The course of most of myocardial lymph vessels follows the position of muscle cells. In the connective septa these vessels join to form larger trunks and open into the subepicardial vessels.     

The effect of cardiopulmonary lymphatic obstruction on heart and lung function

Many thoracic surgical procedures involve excision or destruction of intrathoracic and mediastinal lymphatics. It is widely assumed that the mediastinal lymphatic system is surgically expendable, and that destruction of mediastinal lymphatics has no significant adverse physiological effect. Cardiac lymphatic obstruction may give rise to cardiac lymphedema and impaired cardiac function. Similarly, obstruction of pulmonary lymphatics may result in pulmonary perivascular lymphedema, endothelial injury, and pulmonary artery hypertension. This review summarizes the possible deleterious effects of intrathoracic lymphatic destruction and the benefits of pharmacological and surgical enhancement of active lymph drainage.     

Posterior mediastinal lymph node dissection using the pneumomediastinum method for esophageal cancer

Although posterior mediastinal lymph node metastases are often observed in patients with esophageal cancer, their complete resection via a right thoracic approach is difficult and carries a risk of complications. We have developed a novel procedure for en-bloc dissection of the posterior mediastinal lymph nodes using the pneumomediastinum method. The patient was a 48-year-old female with middle thoracic esophageal cancer. A computed tomography scan showed a posterior mediastinal lymph node 1?cm in diameter. After division of the gastrosplenic ligament by hand-assisted laparoscopic surgery, the esophageal hiatus was opened, and carbon dioxide was introduced into the mediastinum. The anterior and left sides of the distal esophagus were separated, and a swollen posterior mediastinal lymph node was detected. Subsequently, the adventitia of the thoracic aorta was exposed, and the posterior side of the lymph node was separated. While lifting these nodes like a membrane, we cut them along the border of the left mediastinal pleura. Histopathological examination revealed a single squamous cell carcinoma metastasis in the resected lymph node. A good surgical view was obtained in our surgical procedure, and en-bloc dissection of the posterior mediastinal lymph nodes was safely performed.     

Acute obstructive parasternal lymphedema produced in rats without surgery

Although rat red blood cells (RBC) were altered by pretreatment with glutaraldehyde, they nonetheless were well absorbed into mediastinal lymphatics of Lewis rats after intraperitoneal injection. Unlike normal RBC, they did not pass freely through the draining mediastinal lymph nodes. Instead, clumps of free and phagocytosed glutaraldehyde-treated RBC distended and obstructed the afferent lymphatics and the sinuses of draining lymph nodes. The lymphatic obstruction caused edema in a clearly defined compartment of fatty connective tissue between the muscle layers of the ventral chest wall. The obstructive lymphedema interfered with the immunizing effect of small doses of sheep RBC injected intraperitoneally. This study emphasizes the potential utility of the rat's mediastinal lymphatics for studies of lymphatic leakage and obstruction.     

Isolated spread of hepatic metastatic disease to a mediastinal lymph node

The lymphatic system is an important route of spread of hepatic metastatic disease to extrahepatic sites. Although portal and celiac nodes are commonly evaluated both pre- and intraoperatively in patients considered for resection, cephalad sites of drainage of the liver represent a more occult pitfall. We report a case of colon cancer metastatic to the right lobe with an isolated extrahepatic deposit in a mediastinal lymph node. This preoperative diagnosis was confirmed at a subsequent operation, leading to a change in treatment plan. We believe that such occurrences may be unrecognized rather than rare. Careful evaluation of the mediastinum prior to proceeding with hepatic resection may improve patient selection, and hence the outcome, of this procedure.     

Pericardial fluid absorption into lymphatic vessels in sheep

We estimated the volumetric lymphatic clearance rate of pericardial fluid in sheep. In the first group of studies, 125I-human serum albumin (HSA) was injected into the pericardial cavity and after 4 h, various lymph nodes and tissues were excised and counted for radioactivity. Several lymphatic drainage pathways existed defined by elevated 125I-HSA in the middle and caudal mediastinal, intercostal, and the cardiac nodes located near the root of the aorta. In a second group of experiments, the plasma recovery of intrapericardially administered tracer was compared in sheep with intact lymphatics and in animals in which thoracic duct lymph was diverted and other relevant lymphatics ligated. The 4-h plasma recoveries were reduced significantly from an average of 12.2 +/- 3. 4% injected dose in the lymph-intact group to 3.0 +/- 1.1% injected dose in the diverted/ligated group (an inhibition of approximately 75%). In order to estimate the volumetric clearance of pericardial fluid through lymphatics in conscious sheep, 125I-HSA was administered into the pericardial cavity to serve as the lymph flow marker. 131I-HSA was injected intravenously to permit calculation of plasma tracer loss and tracer recirculation into lymphatics. From mass balance equations, total pericardial clearance into lymphatics averaged 1.50 +/- 0.43 ml/h or approximately 1.13 ml/h if one was to assume that the average 25% recovered plasma tracer in lymph diverted/ligated animals was due to nonlymphatic transport. In conclusion, mediastinal lymphatic pathways remove a volume equivalent to the pericardial volume (8.1 +/- 1.1 ml) every 5.4 to 7. 2 h.     

Pathogenesis of varices in schistosomal portal hypertension

Patients with schistosomiasis and portal hypertension have significantly lower levels of hydroxyproline in their saphenous veins and anterior rectus sheaths than do individuals without schistosomal hepatic fibrosis. The stomach of patients with schistosomal portal hypertension demonstrates an increased number of lymphatics by lymphangiography. The disrupted lymph node architecture in these patients could be partially responsible for dilation, tortuosity, and retrograde lymph flow in the gastric lymphatics. These histological and lymphangiographic findings could be attributed to the effect of venous and lymphatic hypertension. A postmortem histological examination of the esophagus of patients with decompensated schistosomal portal hypertension revealed edema of the entire esophageal wall with lymphatic dilation and tortuosity. Based upon these data, we suggest that the varices that develop in patients with schistosomal portal hypertension occur as a consequence of an increased portal venous pressure together with acquired lymphangectasia as well as an intrinsic weakness of the walls of the portosystemic venous channels.     

Renal lymphatic drainage and thoracic duct connections: implications for cancer spread

Studies on renal lymph drainage have generally described lymph nodes without further investigation of the lymph vessels. Our purpose was to revisit this organ to study the vessel drainage pattern. This investigation was performed on 16 refrigerated adult cadavers. After both kidneys were injected with a blue modified Gerota mass, lymph vessels were dissected until their termination. From the right kidneys (n = 13), lymphatics (n = 8) traveling on the anterior aspect of the inferior vena cava were dissected, reaching interaortocaval and more distant nodes, aorta bifurcation (n = 1) and left lateroaortic (n = 1); posterior lymphatics were observed in all subjects, uniformly connecting to the thoracic duct, either after crossing nodes (n = 8) or directly (n = 5). From the left kidneys (n = 13), anterior efferents (n = 16) were dissected, reaching left lateroaortic and also celiac (n = 4) and iliac (n = 1) nodes; posterior lymphatics were also demonstrated, always connecting to the thoracic duct (3 directly). Renal lymphatics have been found to reach very distant nodes as well as always connecting to the origin of the thoracic duct. This feature suggests an important role in both the formation of the thoracic duct and in the spread of renal cancer.     

Mechanical forces and lymphatic transport

This review examines the current understanding of how the lymphatic vessel network can optimize lymph flow in response to various mechanical forces. Lymphatics are organized as a vascular tree, with blind-ended initial lymphatics, precollectors, prenodal collecting lymphatics, lymph nodes, postnodal collecting lymphatics and the larger trunks (thoracic duct and right lymph duct) that connect to the subclavian veins. The formation of lymph from interstitial fluid depends heavily on oscillating pressure gradients to drive fluid into initial lymphatics. Collecting lymphatics are segmented vessels with unidirectional valves, with each segment, called a lymphangion, possessing an intrinsic pumping mechanism. The lymphangions propel lymph forward against a hydrostatic pressure gradient. Fluid is returned to the central circulation both at lymph nodes and via the larger lymphatic trunks. Several recent developments are discussed, including evidence for the active role of endothelial cells in lymph formation; recent developments on how inflow pressure, outflow pressure, and shear stress affect the pump function of the lymphangion; lymphatic valve gating mechanisms; collecting lymphatic permeability; and current interpretations of the molecular mechanisms within lymphatic endothelial cells and smooth muscle. An improved understanding of the physiological mechanisms by which lymphatic vessels sense mechanical stimuli, integrate the information, and generate the appropriate response is key for determining the pathogenesis of lymphatic insufficiency and developing treatments for lymphedema.     

Approaches to resection of recurrent solitary mediastinal lymph nodes after esophagectomy

Esophageal cancer recurrence in solitary mediastinal lymph node that may possibly been left behind in the first surgery differs from other recurrence patterns because it is still local disease and offers the possibility of complete cure through resection, but it is technically difficult. We resected recurrent mediastinal lymph nodes in six cases. A left transthoracic approach was used in three patients. Other approaches were left thoracoabdominal, right open transthoracic and transcervical. R0 resections were achieved in five patients without severe surgical stress or postoperative complications. Overall survival after resection of recurrent lymph nodes was 43 (16–82) months. Approaches to resection of recurrent solitary mediastinal lymph nodes after esophagectomy should be consider to perform curative treatment safely and less invasively.

     

Benign mediastinal lymphadenopathy in congestive heart failure

We report three cases of benign mediastinal lymphadenopathy revealed by chest radiography in patients ranging in age from 61 to 75 years. All three patients had severe coronary heart disease and a history of several episodes of acute cardiac decompensation. Chest CT scanning contributed to the diagnosis by revealing the existence of multiple enlarged lymph nodes, mostly 10 to 17 mm in short-axis diameter. CT scanning also confirmed the disappearance of the mediastinal lymph nodes in one patient on follow-up after treatment with diuretics and digitalis. Histopathology investigations of biopsy samples obtained by mediastinoscopy consistently revealed noninflammatory, benign lesions that did not affect the node structure. Our report draws attention to the particular nosology of left heart disease represented by benign enlarged lymph nodes of the mediastinum and pulmonary edema. The diagnostic approach to such lymphadenopathy should be guided by the radiologic regression seen on follow-up CT scanning while the patient was undergoing appropriate therapy for congestive heart failure, which constitutes a decisive argument for the congestive heart failure origin.     

Sentinel lymph node mapping of the pleural space

STUDY OBJECTIVES: Although the sentinel lymph node (SLN) concept has traditionally been applied to solid organs, we hypothesized that the pleural space might drain into a specific SLN group. The identification of such a nodal group could assist in the staging and treatment of pleural-based diseases, such as mesothelioma, or other lung cancers with visceral pleural invasion. The purpose of this study was to determine whether the pleural space has an SLN group. DESIGN: Sixteen rats underwent right or left pleural space injection of a novel lymph tracer, quantum dots (QDs), which have a hydrodynamic diameter of 15 nm and fluoresce in the near-infrared (NIR) spectrum. Nodal uptake of the entire thorax was imaged with a custom system that simultaneously acquired color video, NIR fluorescence of the QDs, and a merged picture of the two in real-time. Six pigs underwent right or left pleural space injection of QDs and similar imaging. MEASUREMENTS AND RESULTS: In the rat, the QDs drained solely to the highest superior mediastinal lymph node group, corresponding to lymph node station 1, according the regional lymph node classification for lung of the American Joint Committee on Cancer. In one rat, the injection of QDs in the left pleural space resulted in migration to the contralateral station 1 lymph node group. The injection of QDs in the right or left pleural space of the pig resulted in migration solely to the ipsilateral highest superior mediastinal lymph node group. CONCLUSIONS: NIR fluorescence imaging in two species demonstrated that the highest superior mediastinal lymph nodes of station 1 are the SLNs of the pleural space. This study also provides intraoperative feasibility and proof of the concept for identifying lymph nodes communicating with the pleural space on a patient-specific basis, in real-time, and with high sensitivity.     

A quantitative study of the anatomy and distribution of coronary arteries in swine in comparison with other animals and man

The coronary circulation of swine was studied to establish adequate baseline information for using swine in cardiovascular research. Of 65 hearts from domestic and miniature pigs, 45 were injected with a methacrylate plastic and prepared as coronary artery casts whose branches were described and measured, and 20 were injected with different coloured dyes in the right, left anterior descending, and circumflex coronary arteries so that horizontal sections of the heart showed the distribution of each artery and the source of blood supply to particular areas or structures of the heart. Like man, the swine had a left coronary artery that was larger in diameter and longer than the right coronary artery. The right coronary artery was almost always dominant (78%), supplying the posterior septum and atrioventricular node via the posterior descending coronary artery. Eight (17%) of the hearts possessed a balanced blood supply. Two (5%) hearts had a left dominant supply. The intracoronary artery dye injections showed that 72.4% of the right ventricular mass was supplied by the right coronary artery and 27.6% by the left anterior descending coronary artery. In the left ventricle 49% of the mass was supplied by the left anterior descending coronary artery, 25.5% by the right coronary artery, and 25.5% by the circumflex coronary artery. The left anterior descending coronary artery supplied 58% of the interventricular septal mass, while the posterior descending coronary artery supplied 42%. The distribution of the left anterior descending coronary artery branches to the ventricular wall varied inversely in number and size of its diagonal branches (2-9) with the obtuse marginal branches of the circumflex coronary artery which were occasionally more numerous or extended to the apex. The blood supply to the sinoatrial node was always by a branch of the right coronary artery. This analysis shows that not only the coronary anatomy but also the distribution of blood supply to particular areas or structures of the swine heart are very similar to that of humans.     

Mediastinal and hilar lymph node of cancer unknown origin: 3 case reports]

We encountered three rare cases of cancer of unknown origin affecting the mediastinal and hilar lymph nodes. Patient 1 was a 63 year-old man. Chest X-ray and CT films revealed an enlarged right hilar lymph node. A right mediastinal and hilar lymphadenectomy was performed. The histological diagnosis was metastatic squamous cell carcinoma (SCC). SCC of the right upper lobe appeared 34 months after the operation, requiring a right pneumonectomy. Patient 1 was alive 43 months after his first operation. Patient 2 was a 73 year-old man in whom left mediastinal and hilar lymph node swelling had been detected. A mediastinoscopy and lymph node biopsy were performed. The histological findings resulted in a diagnosis of metastatic small cell carcinoma. Chemotherapy was initiated, and the patient was alive 5 months after the biopsy procedure, Patient 3 was a 57 year-old man in whom right mediastinal and hilar lymph node swelling had been disclosed by chest CT scans. We performed a medianosternotomy and mediastinal and right hilar lymphadenectomy. Histologically, the diagnosis was metastatic adenocarcinoma. After the operation, radiation therapy was performed on the patient's mediastinum. Patient 3 was alive 5 months after the initial operation. The patients were given diagnoses of T0N1 or T0N2 lung cancer.     

Coronary artery fistula: 64-slice computed tomographic delineation and correlation with multiplane transesophageal echocardiography and surgical findings

A 49-year-old female who presented with 3 weeks of exertional chest pain had an abnormal mediastinal finding at chest x-ray imaging. Conventional, nongated computed tomography of the chest revealed a "mass" in proximity to the right atrium. 64-slice, cardiac gated computed tomographic coronary angiography, and transesophageal echocardiography delineated the "mass" as a coronary artery fistula structure. The fistula originated from the left main as a tubular vessel that continued into an aneurysmal sac-like cavity that emptied into the superior vena cava near the right atrium. Computed tomographic coronary angiography showed otherwise normal coronary arteries. Findings were ultimately confirmed at cardiac catheterization. Coronary steal was clinically diagnosed and she underwent surgical ligation and resection of the fistula and aneurysm. Her subsequent course was uncomplicated.     

Kugel's artery: an anatomical and angiographic study using a new technique

In this study, we tried to resolve the confusion in the literature regarding the existence and course of Kugel's artery. With the aid of a new technique, we studied 100 human hearts ex vivo by radiography and by direct observation through dissection, to demonstrate anatomical and postmortem angiographic findings of Kugel's artery. Kugel's artery was found in only 6 hearts out of 100 (6%). It originated from the proximal left circumflex artery and ended in the right coronary artery in 2 cases; from the right coronary artery and ended in the same artery in 2 cases; from the left circumflex artery and ended in the same artery in 1 case; and from the right coronary artery through the sinus node artery, ending in the left circumflex artery, in 1 case. In all 100 hearts, an anastomotic network of small atrial branches was found in the same area (lower portion of the interatrial septum), connecting the large vessels indirectly. Branches of the sinus node artery in all hearts, and of the atrioventricular node artery in 66 hearts, participated in this network. Our procedure showed the detailed course of Kugel's artery and its course independent from the atrioventricular node artery and from the anastomotic network. In conclusion, in all cases an anastomotic network of small atrial branches courses through the lower interatrial septum and connects indirectly the proximal and distal ends of the larger coronary arteries. Kugel's artery provides an additional direct arterial anastomosis in the same area in 6% of the hearts.     

Is lobe-specific lymph node dissection appropriate in lung cancer patients undergoing routine mediastinoscopy?

BACKGROUND: The extent and the necessity of lymph node dissection has yet to be defined after resectional surgery for lung cancer. We aimed to analyze the lobe-specific extent of lymph node positivity in patients who underwent preoperative mediastinoscopy as a routine strategy. METHODS: A total of 280 patients with non-small cell lung cancer with negative mediastinoscopy were operated on in our center between January 1997 and June 2003. Hilar and mediastinal lymphadenectomy was performed in every patient. RESULTS: The most commonly involved lymph nodes were found to be paratracheal station lymph nodes (n = 83; 96.5 %) for right upper lobe tumors, subcarinal station lymph nodes (n = 52; 88.1 %) for right lower lobe carcinomas, aorticopulmonary lymph nodes (n = 62; 92.5 %) for left upper lobe and subcarinal station lymph nodes (n = 49; 96.0 %) for left lower lobe tumors. In the patients with right upper lobe, right lower lobe and left lower lobe tumors, the presence of a tumor at these stations was found to be an indicator for poor prognosis ( P = 0.033, P = 0.0038 and P = 0.0016, respectively). Patients with multiple station N2 disease did not survive beyond 3 years. CONCLUSIONS: In patients who underwent routine mediastinoscopy, lobe-specific lymph node dissection could be recommended. Patients with multilevel N2 involvement did not seem to benefit from resectional surgery.     

Quantitative study on the size of coronary artery supplying areas postmortem.

The relative amount of myocardium perfused by the three large coronary arteries was determined in 171 human hearts postmortem. Roentgenograms of transverse serial sections of the ventricular myocardium enabled planimetrical measurements. With little variation, an average of 41.5 per cent of the entire ventricular myocardium was supplied by the left descending coronary artery. Both left branches supplied an average of 63.8 per cent and the right coronary artery supplied 36.2 per cent of the myocardium. The size of supplying areas, in particular that of the right coronary artery and the left circumflex branch, was mainly dependent upon the coronary artery types. As a rule cardiac hypertrophy did not influence the size of coronary supplying areas as much as did the coronary artery types. Only very few hearts revealed that the myocardium was supplied to a greater extent by the right coronary artery than by the left (5.3 per cent). There is a close relationship between the size of the myocardial supplying area and the lumen of the corresponding coronary artery.     

Benign Mediastinal Lymphadenopathy Presenting as Cor Triatriatum

This report describes a patient with a superior mediastinal mass and extensive intrathoracic lymphadenopathy referred for oncologic care. During her evaluation, an abnormal cardiovascular examination resulted in an echocardiographic evaluation and an unanticipated diagnosis of a highly obstructive left atrial cor triatriatum was uncovered. The patient underwent repair of cor triatriatum and lymph node biopsy shortly after the diagnosis was made. The biopsies revealed reactive lymph nodes with lymphatic dilation and no inflammatory or neoplastic features. To our knowledge, this case represents the first pediatric example of extensive mediastinal lymphadenopathy mimicking the appearance of a malignant process as a result of severe pulmonary venous hypertension.