Retrohepatic veins of the posterior section of the right hepatic lobe--terminology and surgical significance

Three main hepatic veins: right, middle and left are constant, but there is a variable number of retrohepatic vessels called accessory or minor hepatic veins. The most important of them are veins reffered to as middle right hepatic vein (MRHV) draining segment VII and inferior right hepatic vein (IRHV) draining segment VI. The incidence of large MRHV and IRHV reaching or exceeding a caliber of 5mm, their arrangement in the liver and drainage territories were investigated in our collection of 142 injection-corrosion specimens of the liver. In 1/5 of the cases with large IRHV this vein drains small part of segment VI, sometimes its insignificant marginal part so it couldn't be used for segment VI preservation when it is necessary. A precise knowledge of the vein anatomy of right posterior sector of the liver and its vein drainage territories is very important during complex dissections of the retrohepatic areas, resections and preservation liver parenchima.     

Beneficial effects of 3-dimensional visualization on hepatic vein reconstruction in living donor liver transplantation using right lobe graft.

BACKGROUND: Recently, virtual operation planning and navigation systems have been introduced in the field of neurosurgery and orthopedic surgery. We report here the beneficial effects of 3-dimensional (3D) visualization on hepatic venous reconstruction in living donor liver transplantation (LDLT) using right lobe graft. METHODS: 3D-image reconstruction of the liver was rendered with 3-mm slices of helical computed tomography (CT) data using zioM900 (Zio Software Inc., Tokyo, Japan). To understand the anatomy of the donor's vessels and design an operation plan, a picture of the vessels in and around the liver was reconstructed. RESULTS: The 3D image demonstrated two short hepatic veins next to the inferior right hepatic vein (IRHV) as well as a large IRHV. The 3D image showed a more precise diameter of the right hepatic vein (RHV) and the IRHV and a more accurate distance between the two hepatic veins than did images measured by 2-dimensional CT. This preoperative information allowed the donor surgeon to dissect the inferior vena cava (IVC) and hepatic veins with reduced blood loss because of reduced risk of injury to the blood vessels. The 3D image revealed that both the RHV and the IRHV branched off at the same angle from the cylindrical IVC. Preoperative planning based on this information secured smooth anastomosis. CONCLUSIONS: 3D visualization is useful for hepatic venous reconstruction of the recipient as well as for donor surgery in LDLT using right lobe graft.     

High dorsal drainage routes of Spiegel's lobe

Abstract. Background/Purpose: The venous drainage from Spiegel's lobe to the terminal portion of the hepatic veins has been described in the literature, but its morphology remains unclear. Methods: We examined 42 dissected liver specimens and 38 cast specimens. Results: In 8 of the 42 dissected liver specimens and 5 of the 38 cast specimens we found atypical but thick (over 3 mm) caudate veins that drained Spiegel's lobe and emptied into the terminal portion (along the most proximal 5-mm course) of the middle hepatic vein (MHV) or the inferior vena cava (IVC) near the MHV terminal (less than 10 mm from the MHV). We termed these the superior caudate vein. This vein ran upward between the caudate portal branches of the left and hilar bifurcation origins or through the territory of the left origin. The superior caudate vein, consistently coexisted with the typical vein(s). We also found several analogues of the superior caudate vein, such as the cranially shifted opening of the typical caudate vein and relatively thick proximal tributaries of the MHV from Spiegel's lobe. Conclusions: Although the superior caudate vein, if present, seemed to have a large role in the venous drainage of the lobe, its incidence seemed to be too low for clinical relevance. Received: May 11, 2001 / Accepted: August 1, 2001     

肝脏右后下静脉的临床解剖学研究

目的 观测肝脏右后下静脉(inferior right hepatic veins,IRHV)的解剖学结构.方法 60具成人尸体肝脏标本,根据肝右后静脉汇入下腔静脉肝后段上、中、下1/3的部位分为上、中、下三组.观察测量IRHV的出现率、数目、口径、肝外行程及其与肝右静脉的关系.结果 IRHV出现率为83.33%,口径为2.62～18.46(14.32±1.21)mm,肝外长度为3.26～47.65(10.78±7.81)mm.IRHV直径与其数量呈负相关.IRHV直径与肝右静脉直径呈负相关,IRHV数量与肝右静脉直径呈正相关.结论 IRHV口径粗大,出现率高,有肝外行程,和肝右静脉呈彼消此长关系.在肝切除术中应注意避免损伤,活体肝移植时应施行IRHV的修复重建.

Abstract：

Objective To observe the anatomy of the inferior right hepatic veins (IRHV).Methods The IRHVs were divided into 3 groups according to the location where they entered into the retrohepatic inferior vena cava at: the upper 1/3, middle or lower 1/3. The incidence, number, caliber, extrahepatic length and the relationship between the major hepatic veins (the right, middle and the left hepatic veins) and the IRHV were observed and measured in 60 adult cadavers. Results The incidence of IRHV was 83.33% with an average diameter of 2.62-18.46(14.32±1.21)mm. Its extrahepatic length was 3.26-47.65 (10.78±7.81)mm. There was a marked negative correlation between the diameter of the IRHV and its number, a marked negative correlation between the diameter of the IRHV and the diameter of the right hepatic vein and a marked positive correlation between the number of the IRHV and the diameter of the right hepatic vein. Conclusions There were high variations in the incidence and anatomy of the IRHV which were related to the diameter of the right hepatic vein. The IRHV was not to be torn during liver resection and should be reconstructed in right liver grafts.     

The caudate processus hepatic vein: a boundary hepatic vein between the caudate lobe and the right liver

OBJECTIVE: This study was conducted to find the boundary vein indicating the intersegmental plane between the caudate lobe and the adjacent liver segments. SUMMARY BACKGROUND DATA: Major hepatic veins of the human liver commonly run through the intersegmental plane and are widely used for the landmarks to define the boundary of both sides of liver segments. As the caudate lobe is a small independent unit of the liver separate from the right and left livers, the existence of the boundary hepatic vein to the adjacent liver segments has been expected. METHODS: Fifty-four adult cadaveric livers were minutely dissected to elucidate the correlation between the portal vein branches and the hepatic veins on both the caudate lobe and the adjacent liver segments. RESULTS: Among the hepatic veins of the caudate lobe, the caudate processus hepatic vein entering the inferior vena cava at hepatic hilum runs in the segmental plane between the caudate processus and the right liver. Three types of the caudate processus hepatic vein directly entering the inferior vena cava and 1 type of the exceptional hepatic vein that was the tributary of the right hepatic vein were observed. They drained the blood of the caudate processus and a part of the right liver, respectively. CONCLUSIONS: The caudate processus hepatic vein is one of the candidates of the hepatic vein indicating the boundary between the caudate lobe and the adjacent liver segments. New procedures will be developed on the liver surgeries by acquiring the anatomic features of this vein.     

Outflow block secondary to stenosis of the inferior vena cava following living-donor liver transplantation?

Although it is well known that outflow block is caused by stenosis or occlusion of hepatic vein anastomoses following living donor liver transplantation (LDLT), there have been few reports on inferior vena cava (IVC) stenosis following LDLT. In this paper, we report two cases of IVC stenosis and hepatic vein outflow block following right hepatic LDLT in the absence of stenosis of any of the anastomoses. Both patients presented with liver dysfunction, an ascitic fluid volume of approximately 2000 mL, and congestion in their biopsy specimens, and venocavography demonstrated IVC stenosis with gradients of more than 10 mmHg in patients with a dominant inferior right hepatic vein (IRHV) anastomosis. After a Gianturco expandable metallic stent successfully implanted in the IVC, the patient's liver function recovered and the volume of ascitic fluid decreased. The pathogenesis of hepatic vein outflow block secondary to IVC stenosis following LDLT may involve the anastomosis with the IRHV, which is the dominant draining vein of the graft and larger than the RHV, caudal to the IVC stenosis and a significant IVC pressure gradient that results in increased IRHV pressure. In conclusion, it is important to include hepatic vein outflow block in the differential diagnosis when patients who have undergone right hepatic LDLT in which anastomosis of the large IRHV has been performed develop manifestations of liver dysfunction.     

Surgical treatment for colorectal liver metastases involving the paracaval portion of the caudate lobe

BACKGROUND: Hepatic neoplasms in the paracaval portion of the caudate lobe (S1r) are usually difficult to treat surgically because such neoplasms often invade the hepatic veins and/or inferior vena cava (IVC). We reevaluated resected cases of colorectal liver metastases involving S1r to confirm the significance of aggressive surgical treatments. METHODS: Between July 1977 and December 2002, 95 consecutive patients with colorectal liver metastases underwent hepatic resection. Seven patients with liver metastases involving the S1r underwent resection. RESULTS: The surgical procedures for liver metastases comprised 3 isolated caudate lobectomies, 2 right hepatectomies, and 2 right hepatic trisectionectomies with caudate lobectomy. Combined resections included partial resection of the hepatic vein in 2 patients, wedge resection of the IVC in 3, and segmental resection of the IVC in 1. Six of the 7 patients with S1r metastasis had recurrent disease in liver and/or lung. A second hepatectomy was carried out in 4 patients and a partial lung resection in 2 patients. Four of the 7 patients survived more than 5 years, but 2 of them died of recurrent disease at 61 and 95 months after initial hepatectomy. The remaining 2 patients are alive 72 and 118 months without any sign of recurrence. The median survival time of the 7 patients was 60 months. CONCLUSION: Liver metastases involving the S1r could be resected radically with en bloc resection of the major hepatic veins and/or the inferior vena cava. An aggressive surgical approach with combined resection of the adjacent major vessels may offer a better chance of long-term survival in selected patients with caudate lobe metastasis from colorectal cancer.     

Sling suspension of the liver in donor operation: a gradual tape-repositioning technique

BACKGROUND: To control bleeding in the deeper parenchymal plane in right hepatectomy, Belghiti et al. (J Am Coll Surg 2001;193:109) proposed a liver-hanging maneuver using a sling passed between the anterior surface of the inferior vena cava (IVC) and the liver parenchyma. We applied this technique in donor operations in which a hepatic parenchymal transection should be performed before dividing the feeding or draining vessels for the graft. METHODS: After passing a tape between the liver and the IVC, the lower tip of the tape is pulled up behind the hepatic hilum to enable effective traction of the dorsal part of the liver. To preserve significant middle hepatic vein (MHV) tributaries in right-liver graft, the tape is gradually repositioned behind the veins, and parenchymal transection is completed before dividing the venous tributaries. Congestion of the graft is minimal until harvest. In right hepatectomy with the MHV, the tape is switched behind the MHV to preserve the MHV. RESULTS: Since March 2000, this technique has been used in 71 consecutive donor operations, including 37 right hepatectomies without the MHV, 8 right hepatectomies with the MHV, 20 left hepatectomies with the caudate lobe, and 6 right lateral sectorectomies. Taping behind the liver was successful in all but one donor (98.6%). There were no major complications related to this procedure. CONCLUSIONS: This new approach to the sling suspension of the liver with a gradual tape manipulation facilitated the suspending action and was useful in four types of donor operation. These techniques are feasible in most living donors and are recommended as basic procedures to enhance the safety of the donor and the quality of the graft.     

Hepatectomy with total vascular exclusion. Anatomical principles based on 64 dissections

Intra-operative hemorrhage is the main surgical risk during liver resections. Nowadays hepatectomies for large or posterior liver tumors close to the hepatocaval junction can benefit from total hepatic vascular exclusion (HVE) involving portal triad exclusion and clamping of the inferior vena cava (IVC) below and above the liver. Anatomical aspects of HVE have been studied in 64 subjects by segmental occlusive phlebographies of the IVC, injection of corrosive substances into the hepatocaval network, biometry of the retrohepatic IVC and serial sections of injected livers. A total HVE should exclude the right suprarenal and phrenic veins. Clamping of the suprahepatic IVC depends on the termination of the left inferior phrenic vein. Clamping of the subhepatic IVC must be retrohepatic: the right lobe of the liver has to be mobilized to free the right border of the retrohepatic IVC into which flows the right suprarenal vein 40 +/- 20 mm above the right renal vein and under the superior right hepatic vein. Both suprahepatic and retrohepatic clamps excluding the retrohepatic portion of the IVC (46.6 +/- 13 mm) and the hepatocaval junction should come in contact behind the IVC without overlapping.     

Adult living donor liver transplantation with right lobe graft: the venous outflow management in the Milan-Niguarda experience

In right lobe living donor liver transplantation (ALDLT), reconstruction of middle hepatic vein (MHV) tributaries is often necessary to avoid severe graft congestion. From March 2001, we performed 36 right lobe ALDLT (segments 5, 6, 7, and 8) without MHV and one pediatric transplant (segments 2 and 3). In the presence of MHV tributaries larger than 5 mm, we intraoperatively evaluated the need for reconstruction. At a mean follow-up of 848 days (range=8-2412), 33/37 transplanted patients are alive with overall patient and graft survivals of 89.2% and 83.8%, respectively. Large MHV tributaries (>5 mm) were present in 10 cases, and inferior right hepatic veins (IRHV) draining segment 6 in 11 cases. In 10 cases, we performed an end-to-side anastomosis between the IRHV and the side of the recipient vena cava. In three cases, the MHV tributaries were end-to-end anastomosed to the stump of the recipient MHV. In all other cases, the vein tributaries were not reconstructed. A computed tomography scan performed from 1 to 3 months after surgery did not show any congested area in the liver parenchyma. In our experience, reconstruction of the MHV tributaries was not always necessary when graft-to-recipient weight ratio is >0.8. Pre- and intraoperative evaluation of the segmental branches of the hepatic vein is crucial to decide about reconstructing these collaterals. Anastomosis of V5 or V8 to the stump of the recipient MHV reduces the number of vascular anastomosis and maintains a physiological angle between these collaterals and the caval vein.     

The paracaval segments of the liver

Two segments constitute thedorsal sector: I to the left and in front of the inferior vena cava, and IX in front and to the right of the cava; they are united inferiorly by the caudate process. Segment I includes the caudate lobe, and segment IX is incorporated in the posterior surface of the right liver. Small dorsal pedicles, which are quite numerous, arise from the posterior margin of the main portal elements, and ascend upward. Segment I receives twigs from the left or right livers, many from the right lateral pedicle (67 biliary branches enter the right lateral duct, the unique duct in three cases). Segment IX consists of three subsegments. IXb lies under the interval between the middle and right superior hepatic veins, in 40% of the cases examined the veins come from the left portal vein or the bifurcation, in 6 cases the ducts enter the left hepatic duct, in 40 cases the branches extend higher than the plane of the main hepatic veins, in 18 cases reaching the upper surface of the liver. IXc is under the right hepatic vein, and IXd is to the right of a vertical plane passing by the right superior vein. Hepatic veins, enter the cava directly, sometimes the middle or the left hepatic veins.     

Variations of hepatic veins: helical computerized tomography experience in 100 consecutive living liver donors with emphasis on right lobe

Anatomical variations in the venous system of liver are not a rarity. A prospective helical computerized tomography (CT) study was undertaken to determine the prevalence of surgically significant hepatic venous anatomic variations among 100 consecutive living liver donors. The studies evaluated the ramification pattern of hepatic veins, the presence of accessory hepatic veins, and of segment 5 or 8 veins (or both) draining into middle hepatic vein. These data obtained by CT influenced surgical planning. Sixty-four donors donated their right lobes and 24 donors, left lateral segments. Only one donor candidate was refused due to combined hepatic and portal venous variations accompanied by multiple bile ducts. Eleven donors were also refused due to reasons other than anatomical variations. Seventeen segment 5 and 17 segment 8 veins draining into middle hepatic vein were anastomosed to inferior vena cava in 23 (36%) of the right lobe liver transplantations. The middle hepatic vein was harvested in only one of the donors. Among the 100 cases, 47 had accessory right inferior hepatic veins, 13 of which were multiple. Twenty-two of the right lobe grafts required surgical anastomoses of these accessory hepatic veins (34%). An isolated hepatic vein anomaly or the presence of accessory hepatic veins are not contraindications to be a living liver donor candidate. However, preoperative knowledge of vascular variations alters surgical management. Helical CT is a valuable tool to delineate the hepatic venous anatomy for surgical planning in living liver donors.     

Right hepatic lobectomy and removal of inferior vena caval tumor embolus in a patient with hepatocellular carcinoma, using veno-venous bypass while preserving perfusion in the remnant liver: A case report

We describe a successful hepatectomy and the removal of a tumor embolus in a 43-year-old woman with hepatocellular carcinoma occupying the right lobe extending to the right branch of the portal vein and the inferior vena cava (IVC). Intraoperative echography revealed the tumor embolus in the IVC to originate from the main tumor via the right inferior hepatic vein, which extended cephalad from the confluence of the right hepatic vein to the IVC. Right hepatc lobectomy was performed via the anterior approach. Using femoro-axillary veno-venous bypass, we opened the IVC at the root of the inferior right hepatic vein to remove the tumor embolus after oblique clamping of the IVC between the right and middle hepatic veins was carried out to preserve perfusion in the remnant liver. Preserving perfusion in the remmant liver in radical hepatectomy for hepatocellular carcinoma with tumor embolism in the IVC appears to be a safe and advantageous technique in patients with poor liver reserve.     

Relation among portal segmentation, proper hepatic vein, and external notch of the caudate lobe in the human liver

OBJECTIVE: To identify portal segmentation and a portal fissure in the caudate lobe of the human liver in relation to the hepatic venous system and the external notch at the caudal edge of the caudate lobe. SUMMARY BACKGROUND DATA: Although the anatomy of the caudate lobe has been studied, the detailed anatomy has not yet been clarified; this is necessary to develop safe procedures for caudate lobe resection. METHODS: A total of 88 formalin-fixed human livers were dissected to visualize the portal vein and hepatic vein systems of the caudate lobe in relation to the external notch. RESULTS: The patterns of portal branching were classified into two types. In 58 livers (67.4%), the territories of the first-order portal branches were clearly divided into two areas (the Spiegel lobe and the paracaval portion). In the remaining 28 livers (32.6%), the territories of the second-order portal branches were clearly divided into two areas. These two areas were distinctly separated by an internal plane, which was coincident with the external notch. The caudate lobe had a systematized hepatic venous system that consisted of one (87.5%) or two (11.4%) proper hepatic veins and plural accessory hepatic veins. The proper hepatic veins laid along the internal plane between these two portal areas. CONCLUSION: The caudate lobe exhibited distinct portal segmentation with a portal fissure that was indicated internally by the proper hepatic vein and externally by the notch at the caudal edge of the caudate lobe.     

肝后隧道手术高危区的解剖特点及临床应用研究

目的:探讨肝后隧道及手术高危区的解剖特点及临床应用价值。方法:解剖20具成人尸体肝脏标本,收集经前入路绕肝提拉法右半肝切除术27例患者的临床资料,分别统计汇入肝后下腔静脉和肝后隧道路径上肝短静脉总数。结果:解剖研究中发现,肝短静脉主要从左右两侧汇入肝后下腔静脉,且较多集中于中、下1/3段;在肝后隧道路径上,汇入肝后下腔静脉的肝短静脉主要集中在下1/3段前方,平均(2.90±1.07)支,上1/3段仅有1例出现1支肝短静脉,中1/3段20例中仅4例出现1支肝短静脉;肝右后下静脉多出现在肝后下腔静脉的中、下1/3段,出现率达85.0%(17/20)。临床手术中发现,在肝后隧道路径上,汇入肝后下腔静脉肝短静脉主要集中在下1/3段,平均(3.21±1.67)支,多数病例此区域上下距离约3～4 cm,同时此区域中肝右后下静脉出现率达85.2%(23/27);27例中仅1例有1支肝短静脉汇入中段肝后下腔静脉前方。结论:肝后隧道手术高危区位于肝后下腔静脉下段前方3～4 cm区域,有较多肝短静脉伴随肝右后下静脉汇入。准确把握此区域的解剖特点并进行解剖分离是成功建立肝后隧道的关键。     

Evaluating the hilar bifurcation territory in the human liver caudate lobe to obtain critical information for delimiting reliable margins during caudate lobe surgery: anatomic study of livers with and without the external caudate notch

Abstract The hilar bifurcation (HB), a wedged portion between the left and right portal vein origins, often issues the caudate branch. However, the HB territory in the caudate lobe has not been well recognized during liver surgery. In 50% of 48 human livers (25 usual livers and 23 with the external caudate notch), the HB gave off thick portal branches (> 1 mm) to supply the caudate lobe. Using minute dissections, we identified four cross-sectional configurations of three subdivisions of the caudate lobe (i.e., left, right, and HB portal territories). The HB territory was consistently located in the paracaval portion, although it sometimes (29.2%: type A) extended slightly or deeply into Spiegel’s lobe. This leftward HB territorial extension was seen more frequently in livers with the notch (43.6%) than in those without it (“usual” livers) (16.0%). Moreover, in livers with the notch the caudate lobe (usually its right portal territory) tended to extend upward and rightward to attach or surround the terminal portion of the right hepatic vein. Our results suggested that in many cases subdivisions of the caudate lobe cannot be divided simply into right and left portions. The HB branch or territory should be examined to determine the real principal border as well as the subdivisional configuration of the caudate lobe. Combined evaluation of the HB branch(es) and external notch could provide critical information for anatomically sophisticated caudate lobe surgery. Electronic Publication     

Liver resection under total vascular isolation. Variations on a theme.

Total vascular isolation (TVI) of the liver was employed during parenchymal transection in 16 patients undergoing hepatic resection for large tumors (mean diameter, 10.7 cm) located near hilar structures, hepatic veins, or the inferior vena cava (IVC). In 14 cases, TVI was achieved by clamping the suprahepatic and infrahepatic IVC and the porta hepatis, with or without aortic occlusion; in two, selective hepatic vein clamping was possible, obviating IVC occlusion. Procedures included standard and extended right and left lobectomies and caudate lobe resections. Concomitant resection and reconstruction of the portal vein (one case), IVC (one case), and bile duct (three cases) was required. Postoperative hepatic and renal failure did not occur. Mean intensive care unit and hospital stays were 2.8 +/- 1.9 and 12.5 +/- 5.2 days, respectively. There were two perioperative deaths. Total vascular isolation permits safe resection of large, critically located tumors that would otherwise present prohibitive operative risks.     

Surgical technique for hepatic venous reconstruction in liver transplantation]

In living-donor liver transplantation, one of the tactics of hepatic vein reconstruction is to obtain a long and wide venous orifice. The short hepatic vein should be reconstructed in the left liver graft with a caudate lobe. In the modified right liver graft, the tributaries of the middle hepatic veins should be reconstructed if there are no communicating veins between the middle and right hepatic veins.     

Anatomical basis of liver hanging maneuver: a clinical and anatomical in vivo study

Liver Hanging Maneuver (LHM) provides better exposure of the deeper section plane together with Inferior Vena Cava (IVC) protection during right hepatectomies without primary liver mobilization. This study assessed the feasibility and complication rates of LHM focusing on the anatomical distribution of the accessory hepatic veins in the retrohepatic portion of the IVC. From January 2002 to December 2005, LHM was planned in 49 consecutive major hepatectomies. The IVC retrohepatic portion was studied during the anhepatic phase in 17 liver transplantations with IVC preservation. The diameter and location of the vein openings were recorded after IVC division into nine portions. LHM was achieved in 47/49 patients (96%). Bleeding occurred in only one patient (2%) and did not entail procedure interruption. The anatomical study revealed a total of 86 veins present in 17 cases (5.18 +/- 4 per patient) and classified them according to diameter (<3, 3 to 6, and >6 mm), as small (n=40), medium (n=29), and large (n=17), respectively. Nine openings were found in the avascular channel for 6/17 (35%) patients (small n=6, medium n=3, large n=0). LHM is a highly feasible procedure with minor bleeding risks due to the lower density and small diameter of short hepatic veins and caudate veins present in the avascular channel.     

主肝静脉和肝短静脉的解剖学研究及其临床意义

目的:探讨主肝静脉和肝短静脉（SHVs）的数量、位置、分型、口径等参数。方法:取60具成人尸体标本, 测量肝左、中、右静脉的肝外长度、注入下腔静脉（IVC）管径;按其SHVs汇入下腔静脉左侧壁、前壁和右侧壁分为左、中、右3排，测量SHVs的数量、位置、口径及其与主肝静脉的关系。结果:肝左、中、右静脉开口于IVC肝后段上l/4段，其中肝左、中静脉共干者73.3%（44例），肝左、中、右静脉共开口者1.7%（1例），3支分别汇入者25.0%（15例），SHVs直径为1.5～17.8（5.4±1.4）mm,3～35支SHV从不同方向和节段注入下腔静脉。肝右静脉直径与SHVs直径呈负相关（r=-0.34，P＜0.05);肝左静脉直径与SHVs数目呈负相关（r=0.24， P＜0.05)。肝右后下静脉（IRHV）出现率为83.3%，平均直径为2.6～8.0（4.3±1.2）mm。结论:SHVs变异较大，管径粗者数量少。SHVs的口径、数目与主肝静脉口径、数目呈相互消长。肝右静脉直径愈大，SHVs直径愈小;反之SHVs直径愈大。肝左静脉直径愈大，SHVs数量愈少;反之SHVs数量愈多。