Annals of the Royal College of Surgeons of England (I974) vol 55 Surgical implications of portal venous system malformation Charles Marks MD MS PhD FRCP FRCS FACS Professor of Surgery, Louisiana State University School of Medicine; Surgeon, Charity Hospital in New Orleans Summary where they empty into the primitive sinus The significance of congenital abnormalities venosus via hepatocardiac channels (Fig. i). in predisposing to portal hypertension and A venous plexus in the caudal portion of variceal haemorrhage needs to be remem- bered when these effects manifest in child- RIGHT LUNG hood, as portal venography will permit BUD elucidation of the complicated congenital RT. POSTERIOR LT; ANTERIOR developmental abnormalities underlying the CARDINAL VEIN CARDINAL VEIN pathological condition and permit rational surgical amelioration. In the presence of portal hypertension the development of a collateral venous circula- ...\t l--l~~~~~~~~~~...... ....... .... ....... tion may be represented by a hepatopetal ~~~~~~~.,:~~ ..................... CARDINAL ~~~~~~~~~~~~~~...".iN-.. ....1 ... ........ .... or hepatofugal circulatory pattern and will SINUS closely parallel the developmental areas where portal and systemic venous circulations meet, being representative of the embryological ANASTOMOSVI . ...... anastomosis between the vitelloumbilical sys- tem and the posterior cardinal system of veins. RIGHT Embryological development of the VEIN IN. portal vein The vitelline and umbilical veins provide VITELLINE venous drainage from the primitive intestinal ARTERY LEFT tract and lead, in complex fashion, to the hA | iX VITELLINE VEIN development of the portal venous system. VI TELGINEDUCT | |GUT Vitelline veins The right and left vitel- line veins develop within the splanchnopleural FIG. I Diagrammatic illustration of relation- mesoderm of the yolk sac wall and extend ship of vitelline veins to midgut in 6-week to the caudal edge of the septum transversum, fetus. 300 Charles Marks the yolk sac wall communicates with thc An S-shaped portal vein is formed and as- umbilical veins via the vitelloumbilical anasto- sumes its adult form because of the plexiform mosis. nature of the embryonic veins and the effect In the 5-week embryo communicating ve- of haemodynamic forces applied along the nous anastomoses develop between the right venous pathway. As the stomach and duo- and left vitelline veins to form a figure-of- denum elongate and rotate from their eiglht pattern in relation to that part of the embryonic midsagittal to adult position the foregut destined to become the duodenum. venous blood proceeds from the left to the The primitive anastomoses include: (i) a right vitelline vein via the dorsal communica- ventral anastomosis caudal to the duodenal tion (Fig. 2). entry of the common bile duct anlage; (2) a Atrophy of the vitelloumbilical duct causes dorsal retroduodenal anastomosis caudal to the distal portion of the vitelline veins to the anlage of the dorsal pancreas; and (3) a atrophy as haemodynamic forces bypass these ventral communication in the region of the vessels. As the superior mesenteric vein differ- porta hepatis. entiates within the mesentery it drains into the left vitelline vein. The splenic vein joins Normal adult configuration Persistence the left vitelline vein at a higher level and of the normal adult portal vein configuration receives the inferior mesenteric vein. depends upon obliteration of: (i) the cranial component of the left vitelline vein; (2) the Umbilical veins The right umbilical caudal component of the right vitelline vein; vein disappears in the 6-7-mm embryo and (3) the ventral intervitelline anastomosis. after undergoing atrophy, so that all the blood from the placenta enters the embryo through the left umbilical vein into the hepa- tic sinusoids. Ductus venosus With the elaboration of the right side of the sinus venosus an enlargement of the hepatic sinusoidal com- munication occurs between the point of entry of the left umbilical vein and the right hepato- cardiac channel, which is the persistent prox- imal part of the right vitelline vein. This channel provides the ductus venosus. After birth the left umbilical vein and the ductus venosus are obliterated and are represented in postnatal life by the liga- mentum teres and the ligamentum venostum respectively. Congenital abnormalities of the portal venous system 9mm normal 9 mm pre-du:cInol Preduodenal and prebiliary configura- FIG. 2 Mechanisms in normal and preduo- tion ofthe portal vein The foramen of denal development of portal vein in 9-mm Winslow or opening to the lesser sac has fetus. at its anterior margin the right free border Surgical implications of portal venous system malformation 301 of the hepatoduodenal ligament. Within this it was joined by two mesenteric veins. The structure are enclosed the common bile duct, portal vein thus formed ran anterior to the the hepatic artery, and the portal vein. The superior duodenal loop and into the lesser normal and conventional anatomical arrange- omentum anterolateral to the common bile rment has the hepatic artery to the left of duct and hepatic artery. the common bile duct and the portal vein Persistence of both the caudal and cepha- situated posterior and between these two struc- lic embryological loops will account for the tures. This arrangement is significant because portal vein anomaly described by Fraser and of the frequent need to explore the common Kingsley-Brown' in which a small normally bile duct in patients with gallstones and com- situated portal vein was associated with a mon duct disorders and when it is necessary large anterior portal channel with multiple to mobilize the portal vein as a preliminary varicosities. to portacaval anastomosis procedures. The portal vein may enter directly into This arrangement may occasionally be al- the inferior vena cava without traversing the tered so that the portal vein lies anterior to liver or it may enter directly into the the common bile duct and hepatic artery. The right atrium. infrequency of a congenital preduodenal por- Absence of the vena cava, though a rare tal vein has recently been emphasized by condition, has been described by Bernard7, in which case its tributaries drain into the Johnson1, and in over i,ooo operative pro- cedures on the portal triad carried out in portal vein. Hypoplasia of the portal vein may occur, the past I o years only 3 patients with a prebiliary portal vein have been found. The with compensatory varicose enlargement of rarity of this condition has also been re- the inferior mesenteric vein and marked ferred to by Greatrex2, Boles and Smith3, hypertension in that segment of the portal and Stengel4. venous system. Under these abnormal circumstances the Duplication of the portal vein Re- arrangement is altered so that the portal vein duplication of the portal vein is an uncom- lies anterior to the common bile duct and mon, albeit a real, developmental anomaly hepatic artery. This rare anomaly is rep- of the portal venous system. A second pre- resented by the portal vein occupying an duodenal portal vein may develop as a result anterior position in the free edge of the lesser of the confluence of the superior mesenteric omentum. It crosses the anterior aspect of vein and the inferior mesenteric vein, which the common bile duct and common hepatic traverses the transverse mesocolon to reach duct, and the persistent caudal-ventral com- the ventral surface of the third part of the municating channel which provides the pre- duodenum and then runs anteriorly to the duodenal component can cause duodenal head of the pancreas. Reaching the gastro- obstruction. hepatic ligament, it then courses anterior to Knight5 recorded an anomalous portal vein the bile duct and hepatic artery to reach the which constituted a surgical danger by vir- liver to the left of the gallbladder fossa, where tue of the splenic vein crossing posterior to it penetrates the quadrate lobe of that organ. the mid-pancreas and emerging just below the The normally situated portal vein is found in pancreatic neck before passing along the sum- such a case as a continuation of the splenic mit of the duodenojejunal flexure to come to vein and is situated in its customary retro- lie anterior to the head of the pancreas, where duodenal retropancreatic situation from where 302 Charles Marks it reaches the hepatoduodenal ligament to corded in I9I3 in association with multiple course to the porta hepatis in its customary cardiac defects12 and was described 3 years relationship to the common bile duct and the later as an isolated entity'3. Weinberg and hepatic artery. Kolson'4 described a triad consisting of pul- Such a malformation may give rise to por- monary-portal venous communication, mul- tal hypertension, with the development of tiple intracardiac anomalies, and partial situs oesophagogastric varices, and may provide a inversus. source of fatal haemorrhage during childhood. During the period I952-72 I,782 patients In such a case described by Snavely and with congenital heart disease have been Breakell8 two separate portal veins were pre- studied at Charity Hospital in New Orleans. sent and these passed over the anterior sur- In this group there were i8 patients with face of the second and third parts of the TAPVD, providing an incidence of i % of all duodenum and the head of the pancreas to cardiac malformations diagnosed clinically. In be joined together in a preduodenal anasto- this group of i 8 patients there were 3 with motic loop at the level of the lower border infradiaphragmatic drainage of the pulmon- of the duodenum. The significance of these congenital abnor- malities in predisposing to portal hypertension and variceal haemorrhage needs to be re- membered, and portal venography would be required to elucidate the congenital developmental abnormality underlying the pathological condition. Portal venous communication with the pulmonary venous system Anomalous pulmonary venous drainage to the portal vein represents a rare expression of total anoma- lous pulmonary venous drainage (TAPVD). TAPVD implies connection of the pulmonary venous system with the systemic system in- stead of the left atrium.