Liver lymphatic drainage patterns follow segmental anatomy in a murine model

The liver’s cellular functions are sustained by a hierarchical, segmentally-organized vascular system. Additionally, liver lymphatic vessels are thought to drain to perihepatic lymph nodes. Surprisingly, while recent findings highlight the importance of organ-specific lymphatics, the functional anatomy of liver lymphatics has not been mapped out. In literature, no segmental or preferential lymphatic drainage patterns are known to exist. We employ a novel murine model of liver lymphangiography and in vivo microscopy to delineate the lymphatic drainage patterns of individual liver lobes. Our data from blue dye liver lymphangiography show preferential lymphatic drainage patterns: Right lobe mainly to hepatoduodenal ligament lymph node 1 (LN1); left lobe to hepatoduodenal ligament LN1 + LN2 concurrently; median lobe showed a more variable LN1/LN2 drainage pattern with increased (sometimes exclusive) mediastinal thoracic lymph node involvement, indicating that part of the liver can drain directly to the mediastinum. Upon ferritin lymphangiography, we observed no functional communication between the lobar lymphatics. Altogether, these results show the existence of preferential lymphatic drainage patterns in the murine liver. Moreover, this drainage can occur directly to mediastinal lymph nodes and there is no interlobar lymphatic flow. Collectively, these data provide the first direct evidence that liver lymphatic drainage patterns follow segmental anatomy.

P5685Abnormal anatomy of the coronary sinus in congenitally corrected transposition of the great arteries (double discordance): a pitfall for transvenous cardiac resynchronization therapy?

Background Congenitally corrected transposition of the great arteries (ccTGA) or double discordance is a rare congenital heart defect associating discordant atrioventricular and ventriculoarterial connections. Late prognosis depends on the progressive failure of the systemic right ventricle (RV). A possible cause for systemic RV dysfunction could be ventricular asynchrony. Cardiac resynchronization therapy (CRT) may thus be indicated in some cases. However, the cardiologists may experience some problems with the coronary sinus (CS) when implanting a 3-lead CRT transvenous system in these patients. Aim of the study To evaluate the anatomy of the CS and cardiac veins in specimens with ccTGA, in order to assess the feasibility of transvenous CRT. Material and methods Among the anatomic collection of the French Centre of Reference for complex CHD, 51 heart specimens had ccTGA with 2 ventricles. There were 33 post-natal and 18 fetal hearts. Hearts were reviewed with special attention paid to the course and drainage of the CS and cardiac veins. Segmental anatomy, location of the ventricular septal defect (VSD), status of the pulmonary outflow tract and anomalies of the atrioventricular valves were reviewed. Results Segmental anatomy was {S,L,L} in 46/51 hearts, {S,L,D} in 2 and {I,D,D} in 3. There was a VSD in 40 (outlet in 25, inlet in 11, both in 2, muscular in 2), pulmonary atresia in 13, subpulmonary stenosis in 6, abnormal tricuspid valve in 20/48 including Ebstein anomaly in 6, straddling in 9 (3 had replacement). The CS was always located behind the morphologically left atrium (LA). However, its anatomy was normal, with normal drainage into the morphologically right atrium, in only 25/51 (49% of cases). The CS was of reduced length with normal orifice in 17. Orifice was atretic with normal size CS in 2, and CS was completely absent in 6 with direct drainage of coronary veins into the LA. At least 1 available vein was found in all cases with patent CS orifice. Conclusion CS in ccTGA is always located behind the morphologically LA. However, its anatomy is abnormal in half of cases. The most frequent anomalies are reduced length (33%) and absent CS or atretic orifice (15.5%). The anatomy of CS should therefore be assessed by imaging techniques (multislice CT imaging or CS venography) before considering transvenous CRT in these patients.

The Angiographic Anatomy of the Sphenoidal Segment of the Middle Cerebral Artery and Its Relevance in Mechanical Thrombectomy

Objective: The middle cerebral artery (MCA) is the most commonly treated artery in mechanical thrombectomy stroke trials; however, there is no pragmatic agreement about the segmental anatomy and nomenclature utilized. It results in significant clinical-radiological dissociation and introduces bias in research trials. The purpose of the study is to review and compare angiographic anatomy with microsurgical anatomy literature of the MCA with emphasis on the discrepancy. Methodology: Consecutive cerebral angiograms between January 2011 and March 2014 were retrospectively reviewed by endovascular surgical neuroradiologists. Information about the anatomy of the sphenoidal segment of the MCA classified as classic and non-classic pattern, the lenticulostriate artery takeoff pattern, and the course angulation of the sphenoidal segment were studied. Results: A total of 500 patients, 886 cerebral angiograms, were reviewed. We found the classic pattern of the main trunk MCA bifurcation and a straight angulation course in less than half of the cases. The lenticulostriate arteries arose not only from the main trunk but also from its divisions in more than half of the cases. Conclusion: It is important to corroborate our findings and to develop a pragmatic classification to accurately assess MCA occlusions from the radiological and clinical perspective.