Age-Related Histological Changes in Vena Caval System of Human Foetus and Adult: A Comparative Study.

BACKGROUND: It has been documented that cardiac musculature is present in both venae cavae, and they contract together with the atrium, contributing to the pumping mechanism of the heart. So, in the present study, we measured the relative thicknesses of the three histological layers at formation, termination and intermediate levels of the venae cavae along with their histological characteristics. MATERIALS AND METHODS: Ten foetal and 10 adult cadavers were used. The Superior and Inferior Venae Cavae from all three regions were excised and processed for histology. The qualitative and quantitative features of the vessels were observed and recorded. The data thus obtained was then assessed statistically. RESULTS: In superior vena cava, the tunica intima grows actively especially during late gestation. The tunica media shows active growth. The tunica adventitia growth is significant at the middle and termination levels. In inferior vena cava, the tunica intima grows actively at the level of formation. The tunica media shows the active overall growth during early gestation. The tunica adventitia shows active growth during late gestation. In qualitative analysis the plump, spindle-shaped primitive mesenchymal cells were observed. Muscle and collagen fibers show reciprocal abundance with increasing age, with the former being lesser in amount than the latter in earlier stages. Appearance of vasa vasorum was notable from 2nd trimester. The cardiac myocytes were located in the middle and outer tunics of the superior vena cava. CONCLUSION: Cardiac musculature was absent in the inferior vena; however, the vessel shows advanced rate of overall development.

The baseline diameter of the inferior vena cava measured by sonography increases with age in normovolemic children.

OBJECTIVES: To evaluate normative sonographic measurements of the inferior vena cava (IVC) diameter in healthy pediatric patients. METHODS: We performed a prospective observational study of a convenience sample of healthy patients between the ages of 0 and 22 years presenting to a pediatric emergency department. Exclusion criteria included abnormal vital signs, pregnancy, or illnesses thought to influence volume status. During quiet respiration, the maximum and minimum IVC diameters were measured in the sagittal plane distal to the hepatic vein-IVC junction. As second measurements, the maximum diameters of the IVC and aorta were measured in the transverse plane distal to the insertion of the left renal vein into the IVC. RESULTS: From February 2013 through April 2014, 63 children (51% female; mean age, 11 years) were enrolled. There were 20 children in each age group of 2 to 7, 7 to 12, and 12 to 22 years. The correlations between IVC and aortic diameters as a function of age were calculated using the Spearman rank correlation coefficient. The correlation coefficients were all statistically significant (P < .001): sagittal maximum IVC diameter (0.81), sagittal minimum IVC diameter (0.79), transverse maximum IVC diameter (0.79), and transverse maximum aortic diameter (0.81). CONCLUSIONS: This pilot study of sonographic measurements of the IVC diameter in normovolemic children suggests a statistically significant positive correlation between age and IVC diameter. Future studies should focus on multicenter enrollment, children in the youngest age group, and the development of normative growth curves for the IVC by age, sex, and body mass index.

Longitudinal growth of the autologous vessels above and below the Gore-Tex graft after the extracardiac conduit Fontan procedure.

OBJECTIVE: Reflecting excellent mid-term outcomes, extracardiac conduit Fontan procedure (ECFP) using Gore-Tex tube graft has been performed with increasing frequency in patients with functional single ventricle. Nevertheless, due to the lack of growth potential of the artificial conduit, the status of the venous pathway along with somatic growth is a continuing concern. In this study, we evaluated the longitudinal growth of the autologous vessels above and below the Gore-Tex graft used in the ECFP. METHODS: This study included 34 patients who had completed cardiac catheterisations at 1 month and 5.1 years after the ECFP. The average age, weight and height at the ECFP were 3.8+/-2.5 years (1.8-12.7 years), 12.7+/-4.6 kg (7.4-33.0 kg) and 92.9+/-16.1cm (72.5-153.5 cm), respectively. We measured the vertical lengths of three different parts angiographically: the length between the confluence point of the innominate vein and the anastomotic site of the conduit to the pulmonary artery (SVC-C), the conduit vertical length (C) and the length between the confluence point of the hepatic vein and the conduit's anastomotic site to the inferior vena cava (IVC-C). RESULTS: We have not observed stenosis or thrombus formation in the conduit or distortion of the conduit or pulmonary artery in any of the cases. No intervention or re-operation related to the extracardiac conduit was required, and laminar flow through the conduit was maintained with efficient Fontan haemodynamics. At 5.1 years after the ECFP, the average weight and height gain were 10.3+/-4.4 kg and 28.5+/-1.9 cm, respectively. The length of SVC-C, C and IVC-C were significantly increased as 124+/-15%, 106+/-7% and 132+/-24%, respectively, compared to the lengths at 1 month after the ECFP. The degree of increase in SVC-C and IVC-C was significantly larger than that in C. CONCLUSIONS: Along with the patient's somatic growth, longitudinal growth of the autologous vessels above and below the Gore-Tex graft was demonstrated to compensate for the lack of growth potential of the artificial graft.

Vascular patches tissue-engineered with autologous bone marrow-derived cells and decellularized tissue matrices.

Synthetic polymer vascular patches used in cardiovascular surgery have shortcomings such as thrombosis, intimal hyperplasia, calcification, infection, and no growth potential. Tissue-engineered vascular patches using autologous vascular cells may solve these problems. In this study, we developed a tissue-engineered vascular patch using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices. Vascular smooth muscle cells and endothelial cells were differentiated from bone marrow mononuclear cells in vitro. Tissue-engineered vascular patches were fabricated by seeding these cells onto decellularized canine inferior vena cava matrices and implanted into the inferior vena cava of dogs. Three weeks after implantation, the tissue-engineered vascular patches were patent with no sign of thrombus formation. Histological, immunohistochemical, and electron microscopic analyses of the vascular patches retrieved 3 weeks after implantation revealed regeneration of endothelium and smooth muscle and the presence of collagen and elastin. BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular patches, indicating that the BMCs survived after implantation and contributed to the vascular tissue regeneration. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and decellularized tissue matrices.

Novel growth stent for the permanent treatment of vessel stenosis in growing children: an experimental study.

Stent implantation in stenotic vessels of infants and small children is problematic because there is no ideal stent model that is small enough to be easily introduced into the infant femoral vein or artery and, at the same time, large enough to be dilated during growth to adult vessel diameters. To overcome this problem, we designed a new stent, the growth stent. This growth stent is a balloon-expandable metal stent. Two longitudinal halves are connected with bioabsorbable sutures so that a circular stent is created. It was postulated that after absorption of the sutures the stent would not impede growth. Twenty of these stents were implanted in the aorta, pulmonary arteries, and inferior vena cava of piglets (average weight 6.9 kg). After 18 weeks (14-23 weeks) and a mean weight gain of 59 kg, none of the stented vessels showed any significant stenosis or pressure gradient, documented by angiography and catheter pullback. During fluoroscopy, the two halves of the stent were clearly separated in all animals. The growth stent has the potential to be nonrestrictive during vessel growth, and thus is a promising new device for the permanent treatment of stenotic vessels in infancy and childhood.

Morphologic and biochemical features affecting the antithrombotic properties of the inferior vena cava of rabbit pups and adult rabbits.

The incidence of venous thromboembolic disease is reduced in children compared with adults. Thromboprotective mechanisms, some of which have already been identified in plasma, must be present in children. Blood vessel walls have important antithrombotic properties that maintain blood fluidity. This is in part due to proteoglycan (PG)-related glycosaminoglycan (GAG) molecules within vessel walls. PGs are macromolecules with covalently attached GAG chains, either chondroitin, dermatan, heparan, or keratan sulfate. The influence of age on the concentration and anticoagulant activities of PGs and GAGs, within vein walls before puberty has not been previously investigated. We hypothesized that developmental differences in vein walls may contribute to the reduced risk of thrombosis in children. We used a rabbit model to examine morphologic and biochemical features of inferior venae cavae (IVCs). We assessed IVC wall morphology, PG distribution, GAG mass, and GAG antithrombin activity. Morphologically, there were only minor differences between pups and adult rabbits' IVCs. However, there was a significant increase in GAGs by mass in IVCs from pups compared with adult rabbits (p = 0.012). In addition the total antithrombin activity (p = 0.04), and especially that of heparan sulfate (p = 0.01) was significantly increased in pups compared with adult rabbits. These results demonstrate important differences in the antithrombotic properties of IVC walls in pups and adult rabbits. In summary, developmental differences in vein wall PG content and activity exist which may contribute to the reduced risk of venous thromboembolism in children. Further characterization of these differences is required.

Improved growth with bioabsorbable sutures in both high- and low-pressure zones.

BACKGROUND: Compromised growth after operation remains a significant problem in the cardiovascular field. Some benefit of absorbable suture materials has been demonstrated for arterial anastomoses. However, for the low-pressure zone, few data are available. METHODS: To assess growth in high- versus low-pressure zones we transected the abdominal aorta (high-pressure zone) as well as the inferior vena cava (low-pressure zone) in 10 young mongrel dogs using for reanastomosis 7-0 nonabsorbable versus absorbable running sutures in random order. RESULTS: All animals survived and were evaluated over 12 months including body weight (gain, 212% +/- 45% for nonabsorbable versus 218% +/- 8% for absorbable; not significant), angiography, and, after elective sacrifice, detailed studies of aorta and vena cava. Systematic complication of angiographic data at 12 months showed at the suture level an area of 13.8 mm2 for nonabsorbable versus 24.3 +/- 14.4 mm2 for absorbable sutures in the high-pressure zone as compared with 12.9 +/- 4.9 mm2 for nonabsorbable versus 25.3 +/- 15.4 mm2 for absorbable sutures in the low-pressure zone. Residual lumen, calculated as a function of the area above and below the suture, accounted for 35% +/- 10% for nonabsorbable versus 92% +/- 12% for absorbable sutures (p < 0.001) in the high-pressure zone as compared with 37% +/- 13% for nonabsorbable versus 75% +/- 15% for absorbable sutures (p < 0.003) in the low-pressure zone (high versus low, not significant). Poststenotic dilatation accounted for 199% +/- 22% for nonabsorbable versus 126% +/- 43% for absorbable sutures (p < 0.01) in the high-pressure zone. In the low-pressure zone, poststenotic dilatation remained below the inflow area, and the residual poststenotic lumen accounted for 52% +/- 14% for nonabsorbable versus 77% +/- 16% for absorbable sutures (p < 0.004). Macroscopic, light, and scanning electron microscopic studies confirmed different growth patterns in high- versus low-pressure zones. CONCLUSIONS: Aortic narrowing resulted in poststenotic dilatation and unrestricted outflow path (hourglass-type stenosis). Caval narrowing was followed by restriction of poststenotic outflow path (funnel-type stenosis). Absorbable suture material allows for superior growth in both high- and low-pressure zones.

Palmaz stent in the treatment of central venous stenosis: safety and efficacy of redilation.

PURPOSE: To assess the safety and efficacy of redilation of central venous stents in a growing animal model. MATERIALS AND METHODS: Palmaz stents were placed in the inferior vena cava (IVC) in 18 newborn lambs. After 5 months, vena cavography was performed. Those animals in which growth of the IVC adjacent to the stent and/or neointimal hyperplasia had resulted in a stenosis were considered candidates for redilation. Repeat vena cavography, intravascular ultrasound, and histologic examination were performed at 2 or 6 months. RESULTS: A stenosis of > 20% was demonstrated in 13 animals. Redilation was performed, and a 50% mean increase in stent diameter was achieved. There were no immediate complications. Late complications included nonocclusive laminar clot (n = 2), and a bar of tissue dividing but not occluding the caval lumen (n = 1). Moderate neointimal hyperplasia occurred in all stents. Stent compression (unrelated to redilation) occurred in seven animals. CONCLUSION: Palmaz stents can be redilated safely and effectively in an animal model of growing central veins.

[Quantitative analysis of the development and age-related anatomy of the inferior vena cava in human ontogeny]. / Kolichestvennyi analiz razvitiia i vozrastnoi anatomii nizhnei poloi veny v ontogeneze cheloveka.

Periods of intensive changes and phases of a relative stabilization are observed in the inferior vena cava development. By the 4th month of the prenatal period of ontogenesis the inferior vena cava is completely formed and further its general plan of development has no any principle differences. In fetuses and children there is an essential increase of the lumen, length and angle in the inferior vena cava formation. An intensive growth of the transversal section area of the inferior vena cava initial portion in infants is connected with transition to vertical position and an increasing hydrodynamic loading in the mentineed portio of the inferior vena cava. In fetuses, newborns and children up to 12 years of age the inferior vena cava has a high level of formation, that corresponds to position of III--IV lumbar vertebrae. A statistically significant increase in the inferior vena cava parameters is noted in the adolescent period, which result from a general intensive development of the human organism ad its vascular system, in particular. At this age the level of the inferior vena cava formation descends up to the area of the IV--V lumbar vertebrae. Intensive changes in the inferior vena cava size is completed by the end sexual maturation. In the first and second mature ages a phase of a relative stabilization in the inferior vena cava development is noted. In elderly and old ages certain vasodilatation and elongation of the inferior vena cava is observed. Its formation area descends to the level of V lumbar -- I sacral vertebrae. Correlative analysis has proved the main stages in the development of the vessel studied, and the regression equations obtained can be used as an additional method for defining age of the corpse when a forensic medical examination is performed.

Pseudoendothelium formation in expanded polytetrafluoroethylene grafts implanted in the inferior vena cava of normal and defibrinogenated dogs.

The outgrowth of endothelial cells in an expanded polytetrafluoroethylene graft implanted in the canine inferior vena cava was studied by scanning electron microscopy. The adjacent endothelial cells of the vena cava started to invade the anastomotic area three days after the implantation and reached approximately the central part of the 2-cm-long graft after 21 days. There was no obvious difference in the process of endothelialization between the control group and the moderately defibrinogenated group, in which the fibrinogen concentration was at most 0.72-0.87 gm/L. A slight delay in the outgrowth of endothelial cells was noted within the first seven days in the severely defibrinogenated group, in which the fibrinogen concentration was below 0.40 gm/L. After 70 days, all grafts were completely covered by endothelial cells. The structural difference of the mural thrombus resulting from reduced fibrin formation might be a major factor influencing the endothelium formation.