The three fetal shunts: A story of wrong eponyms.

The fetal circulatory system bypasses the lungs and liver with three shunts. The foramen ovale allows the transfer of the blood from the right to the left atrium, and the ductus arteriosus permits the transfer of the blood from the pulmonary artery to the aorta. The ductus venosus is the continuation of the umbilical vein, allowing a large part of the oxygenated blood from the placenta to join the supradiaphragmatic inferior vena cava, bypassing the fetal liver and directly connecting the right atrium. These structures are named after the physicians who are thought to have discovered them. The foramen ovale and the ductus arteriosus are called the "foramen Botalli" and the "ductus Botalli," after Leonardo Botallo (1530-c. 1587). The ductus venosus is styled "ductus Arantii" after Giulio Cesare Arantius (1530-1589). However, these eponyms have been incorrectly applied as these structures were, in fact, discovered by others earlier. Indeed, the foramen ovale and the ductus arteriosus were described by Galen of Pergamon centuries earlier (c. 129-210 AD). He understood that these structures were peculiar to the fetal heart and that they undergo closure after birth. The ductus venosus was first described by Andreas Vesalius (1514-1564) 3 years before Arantius. Therefore, the current anatomical nomenclature of the fetal cardiac shunts is historically inappropriate.

Circulatory changes associated with the closure of the ductus arteriosus in hatching emu (Dromaius novaehollandiae).

In developing avian embryos, the right and left ductus arteriosi (DA) allow for a shunt of systemic venous return away from the lungs to the body and chorioallantoic membrane (CAM). Unlike in mammals where the transition from placental respiration to lung respiration is instantaneous, in birds the transition from embryonic CAM respiration to lung respiration can take over 24h. To understand the physiological consequences of this long transition we examined circulatory changes and DA morphological changes during hatching in the emu (Dromaius novaehollandiae), a primitive ratite bird. By tracking microspheres injected into a CAM vein, we observed no change in DA blood flow between the pre-pipped to internally pipped stages. Two hours after external pipping, however, a significant decrease in DA blood flow occurred, evident from a decreased systemic blood flow and subsequent increased lung blood flow. Upon hatching, the right-to-left shunt disappeared. These physiological changes in DA blood flow correspond with a large decrease in DA lumen diameter from the pre-pipped stages to Day 1 hatchlings. Upon hatching, the right-to-left shunt disappeared and at the same time apoptosis of smooth muscle cells began remodeling the DA for permanent closure. After the initial smooth muscle contraction, the lumen disappeared as intimal cushioning formed, the internal elastic lamina degenerated, and numerous cells underwent regulated apoptosis. The DA closed rapidly between the initiation of external pipping and hatching, resulting in circulatory patterns similar to the adult. This response is most likely produced by increased DA constriction in response to increased arterial oxygen levels and the initiation of vessel remodeling.

Reference ranges of ductus arteriosus derived by cardio-spatiotemporal image correlation from 14 to 40 weeks of gestation.

OBJECTIVE: To construct reference ranges of fetal ductus arteriosus (DA) derived by volume datasets of cardio-spatiotemporal image correlation (cardio-STIC). METHODS: Cardio-STIC volume datasets were acquired from low-risk singleton pregnancies with a reliable gestational age from 14 to 40 weeks. In offline analysis with 4D View version 9, fetal DA was measured in the transverse ductal arch view with orthogonal control in the multiplanar view. The reference ranges of the DA and Z-score equation were constructed against gestational weeks and biparietal diameter (BPD) as independent variables. RESULTS: A total of satisfactory 606 volumes were analyzed. The reference ranges for predicting means and SDs of fetal DA were constructed based on the best-fit regression model. Mean DA (mm) was best predicted by linear model as a function of GA (weeks) and BPD (cm) as follows: Predicted DA diameter (cm) = -0.051 + 0.014 × GA (weeks) (r = 0.84) and Predicted DA diameter (cm) = -0.015 + 0.053 × BPD (cm) (r = 0.83). Models for Z-score calculation and centile charts for predicting fetal DA were also provided. CONCLUSION: Reference ranges of the fetal DA and Z-score model are provided. These may serve as a useful tool in the assessment of fetal DA, especially in fetal cardiac anomalies or in monitoring fetuses exposed to maternal indomethacin.

Leonardo Botallo (1530-1587) and his pioneering contributions to traumatology, cardiology and deontology.

Leonardo Botallo (1530-c. 1587) is widely known for the eponymous "foramen Botalli" and "ductus Botalli". The first, most commonly named "foramen ovale", allows blood in the fetal heart to enter the left atrium from the right atrium. The second, named "ductus arteriosus", consists of a blood vessel in the developing fetus connecting the trunk of the pulmonary artery to the proximal descending aorta. However, Botallo was a multifaceted figure who studied many aspects of human anatomy and physiology, also making important contributions to clinical and surgical practices. Moreover, as we will see in the last section of this paper, Botallo wrote a book on medical deontology having significant features in relationship to the history of medical ethics. Botallo's multidisciplinary approach is a typical characteristic of Renaissance physicians and scientists, who contributed to making this period a fundamental prelude to the scientific revolution of the 17th century.

[Postnatal changes in the ductus arteriosus and brown adipose tissue: a review and an exploratory post-mortem study of lambs]. / Postnatale effecten op de ductus arteriosus botalli enhet bruin vetweefsel. Een literatuuroverzicht en een exploratief post-mortemonderzoek bij lammeren.

After a short review of the literature, postnatal changes in the ductus arteriosus Botalli are described in 52 lambs sampled in 1970 and 1971. Five groups of animals were formed on the basis of findings. (I) All lambs (n = 18) that died of asphyxia or prematurity had open ducti and, in most cases, severe adventitial bleeding (2). Completely anatomically closed ducti were found in I-week-old lambs (n = 9). Lambs that died within about 4 days of birth were grouped as (3) low-birth weight (dysmaturity) (n = 2), (4) normal weight and died after bacterial infection (n = 7), or (5) normal birth weight and died of other causes (n = 6). The dysmature lambs died because of cold and poor suckling. Compared with the lambs with a normal body weight, the dysmature lambs had almost completely closed ducti. Extensive, often circular, haemorrhages at the periphery of the necrotic muscular tissue of the ductal media were found in the dysmature and infected lambs. In these lambs, the brown adipose tissue surrounding the ductus was red-brownish and often depleted of its fat. This fat depletion and haemorrhages were less severe in lambs that died of other causes. The haemorrhages in the media of the ductus arteriosus, which were not found in older lambs, have not been described previously in other species, including humans. These haemorrhages are most likely the result of a short period of ductal relaxation, resulting in the passage of blood through the vasa vasorum and leakage of blood cells from degenerated capillaries at the border of the necrotic muscular tissue. It is hypothesized that the relaxation results from one or a combination of the following: (i) direct heat from heat-producing brown adipose tissue surrounding the ductus (because of cold or infection), (2) infection or inflammatory mediators, and (3) adipose tissue-derived relaxing factors.

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sagittal sections.

BACKGROUND: At birth, the ductus arteriosus (DA) merges with the aortic arch in the slightly caudal side of the origin of the left subclavian artery (SCA). Since the SCAs (7th segmental arteries) were fixed on the level of the 7th cervical-first thoracic vertebral bodies, the confluence of DA should migrate caudally. We aimed to describe timing and sequence of the topographical change using serial sagittal sections of 36 human embryos and foetuses (CRL 8-64 mm; 5-10 weeks), Those made easy evaluation of the vertebral levels possible in a few section. MATERIALS AND METHODS: The DA or 6th pharyngeal arch artery seemed to slide down in front of the sympathetic nerve trunk along 1.0-1.2 mm from the second cervical vertebral level at 5-6 weeks and, at 6 weeks (CRL 14-17 mm), the DA confluence with aorta reached the 7th cervical level. Because of the highly elongated common carotid artery, the sliding of DA confluence seemed to be much shorter than the cervical vertebrae growing from 1 mm to 2.4 mm. RESULTS: At the final topographical change at 6-7 weeks, the DA confluence further descended to a site 1-vertebral length below the left SCA origin. From 6 to 9 weeks, a distance from the top of the aortic arch to the left SCA origin was almost stable: 0.3-0.5 mm at 6 weeks and 0.4-0.6 mm at 9 weeks. CONCLUSIONS: The heart descent and the caudal extension of the trachea and bronchi, those occurred before the DA sliding, were likely to be a major driving force for the sliding.

Comparative physiology of the ductus arteriosus among vertebrates.

The ductus arteriosus is typically viewed as a mammalian fetal blood vessel providing a right-to-left shunt of right ventricular outflow away from the lungs and to the systemic circuit, that must close at birth. This review provides a wider comparative examination of the ductus arteriosus in lungfish, reptiles, birds, and mammals. The ductus arteriosus evolved with the lung in the ancestors of the lungfish as a connection between the pulmonary arteries and dorsal aorta. During embryonic development, reptiles, birds, and mammals all possess either one or two paired ductus arteriosi that provide a fetal shunt of blood away from the lungs. Differences in the fetal circulatory arrangement are seen between these groups and this influences the importance of the ductus arteriosus as an embryonic shunt. The ductus arteriosus from lungfish and tetrapod vertebrates is an oxygen sensitive blood vessel, with shared conserved pathways involved in oxygen sensing. By expanding studies into more comparative models such as lungfish or developing birds a better understanding of the physiology of the ductus arteriosus can be developed.

Morphometric study of the ductus arteriosus during human development.

During prenatal life, the ductus arteriosus connects the left pulmonary artery and the descending aorta. Morphometric features (length, external diameter, volume) of the ductus arteriosus in 131 human fetuses (65 males, 66 females) were studied by means of anatomical, digital and statistical methods. Regression analysis was used to investigate the growth of the ductus arteriosus during gestation. The values of the length of the ductus arteriosus ranged from 3.95 mm for the 15 week gestational group to 12.20 mm for the 34th week of gestation. The length of the ductus arteriosus related to fetal age (x) increased according to the linear function y = -3.0726 + 0.4381x. The mean values of the diameter of the ductus arteriosus ranged from 1.34 to 3.49mm for the 15 and 34 week gestational groups, respectively. The growth of the ductus arteriosus diameter followed in accordance with the linear function y = 0.2072 + 0.0935x. The mean values of the ductus arteriosus volume ranged from 5.08 mm3 for the 15 week group to 117.30 mm3 of the 34 week gestation group. The volume growth increased according to the function y = 0.0007x3.3782. Positive correlation coefficients between arterial parameters and fetal age were statistically significant (P < or = 0.01) and reached the following values: r1 = 0.98 for Length, r2 = 0.90 for diameter and r3 = 0.94 for volume. Despite the increase in absolute diameter, the relative diameter of the ductus arteriosus (ductus arteriosus-to-aortic bulb diameter ratio) decreased from 0.80 to 0.48.

Tetralogy of Fallot Surgical Repair: Shunt Configurations, Ductus Arteriosus and the Circle of Willis.

In this study, hemodynamic performance of three novel shunt configurations that are considered for the surgical repair of tetralogy of Fallot (TOF) disease are investigated in detail. Clinical experience suggests that the shunt location, connecting angle, and its diameter can influence the post-operative physiology and the neurodevelopment of the neonatal patient. An experimentally validated second order computational fluid dynamics (CFD) solver and a parametric neonatal diseased great artery model that incorporates the ductus arteriosus (DA) and the full patient-specific circle of Willis (CoW) are employed. Standard truncated resistance CFD boundary conditions are compared with the full cerebral arterial system, which resulted 21, -13, and 37% difference in flow rate at the brachiocephalic, left carotid, and subclavian arteries, respectively. Flow splits at the aortic arch and cerebral arteries are calculated and found to change with shunt configuration significantly for TOF disease. The central direct shunt (direct shunt) has pulmonary flow 5% higher than central oblique shunt (oblique shunt) and 23% higher than modified Blalock Taussig shunt (RPA shunt) while the DA is closed. Maximum wall shear stress (WSS) in the direct shunt configuration is 9 and 60% higher than that of the oblique and RPA shunts, respectively. Patent DA, significantly eliminated the pulmonary flow control function of the shunt repair. These results suggests that, due to the higher flow rates at the pulmonary arteries, the direct shunt, rather than the central oblique, or right pulmonary artery shunts could be preferred by the surgeon. This extended model introduced new hemodynamic performance indices for the cerebral circulation that can correlate with the post-operative neurodevelopment quality of the patient.

Patency of the ductus arteriosus in normal neonates: two-dimensional echocardiography versus Doppler assessment.

Two-dimensional echocardiography using a high resolution, 7.5 ,Jsz transduce was compared with Doppler echocardiography for the assessment of patency of the ductus arteriosus in normal newborn infants. Twenty-eight neonates were studied between 1 and 10 hours (mean 5.5) after birth and both examinations were possible in 27 (96%). Doppler echocardiography under two-dimensional direction indicated ductal patency in all 27 neonates. Doppler sampling in the pulmonary end of the ductus rather than the main pulmonary artery was more sensitive for detecting patency. When two-dimensional echocardiography only was used to predict patency, there was 85% sensitivity. Two-dimensional echocardiography showed no evidence of ductus arteriosus narrowing ion four neonates studied shortly after birth. In 18, the pulmonary portion of the ductus arteriosus appeared narrowed and in 8 of these, the narrowing extended toward the mid-portion of the ductus. In five others, there was only mid-ductus arteriosus narrowing. It is concluded that high resolution two-dimensional echocardiography can be used to assess ductus arteriosus morphology, but is limited in predicting ductal patency near the time of normal physiologic closure. Combined two-dimensional and Doppler echocardiography is a highly sensitive technique for detection of ductal patency when sampling is performed in the pulmonary end of the ductus arteriosus.

Histologic studies on normal and persistent ductus arteriosus in the dog.

The process of anatomic closure of the ductus arteriosus was studied at the ultrastructural level in 15 normal beagles (age 0 hour to 13 days) and in 18 specimens from a strain of dogs with hereditary persistent ductus arteriosus (age 4 hours to 27 days). Normal ductal closure takes place from the pulmonary artery to the aortic end. It is accompanied by a series of histologic changes: 1) separation of the endothelial cells from the internal elastic lamina resulting in a wide region of subendothelial edema; 2) ingrowth and infolding of endothelial cells and migration of undifferentiated smooth muscle cells from the inner media into the subendothelial region; 3) apposition of endothelial cells bordering the lumen; and 4) degenerative changes. In persistent ductus arteriosus, these changes do not occur. The endothelial cells remain closely adhered to the internal elastic lamina and the underlying media is abnormal in structure. In the case of partial persistent ductus arteriosus (ductus diverticulum), both the normal and the abnormal type of wall are found in a single ductus arteriosus. The histologic features of the normal and the persistent ductus arteriosus in the dog resemble those of the normal and the persistent ductus arteriosus in humans, suggesting a similar pathogenesis.

Formation of intimal cushions in the ductus arteriosus as a model for vascular intimal thickening. An immunohistochemical study of changes in extracellular matrix components.

There is a great resemblance in the sequence of events that take place in the pathological development of intimal thickening, so called arteriosclerosis and the formation of intimal cushions in both the normal ductus arteriosus (DA) and the persistent ductus arteriosus (PDA). The human DA was used as a model to study the changes in the extracellular matrix during this process with immunohistochemistry. The formation of intimal cushions was studied in 4 normal fetal DA, 4 normal mature DA and 3 persistent DA. The process of intimal thickening in the fetus starts in the second trimester of pregnancy with an accumulation of glycosaminoglycans in the subendothelial region (SER), accompanied by separation of endothelial cells from the internal elastic lamina and followed by migration of smooth muscle cells into the subendothelial region. This phenomenon was also observed in the mature DA in the neonate, indicating that cushion formation is a continuous process. Intimal cushions had also developed in the persistent DA, although they were morphologically different from the cushions found in the normal mature DA. It was remarkable that two elastic lamellae could be distinguished: one at the original site on the borderline of intimal cushion and media and the other in a subendothelial position. The endothelial cells were firmly attached to this subendothelial lamina, which was wrapped in the basal lamina components laminin and type IV collagen. The main morphological difference between the normal mature DA and the persistent DA is the close relation between endothelial cells and the subendothelial elastic lamina, suggesting an altered elastin metabolism in the PDA. PGI2 synthase was increased in the wall of both the normal and persistent DA as compared with the aorta. It may be related to a role of PGI2 in the formation of intimal cushions.

Carbon monoxide-induced relaxation of the ductus arteriosus in the lamb: evidence against the prime role of guanylyl cyclase.

1. We have previously found that carbon monoxide (CO) potently relaxes the lamb ductus arteriosus and have ascribed this response to inhibition of a cytochrome P450-based mono-oxygenase reaction which sustains contractile tone. Our proposal, however, has been questioned on the evidence of findings in other blood vessels implicating the guanylyl cyclase-based relaxing mechanism as the target for CO. To investigate this issue further, we have carried out experiments in the isolated ductus from near-term foetal lambs and have examined the effect of CO concomitantly on muscle tone and cyclic GMP content, both in the absence and presence of guanylyl inhibitors, or during exposure to monochromatic light at 450 nm. 2. CO (65 microM) reversed completely, or nearly completely, the tone developed by the vessel in the presence of oxygen (30%) and indomethacin (2.8 microM). Cyclic GMP content tended to increase with the relaxation, but the change did not reach significance. Sodium nitroprusside (SNP), a NO donor, mimicked CO in relaxing the ductus. Contrary to CO, however, SNP caused a marked accumulation of cyclic GMP with levels being positively correlated with the relaxation. 3. Methylene blue (10 microM) reduced marginally the CO relaxation, whilst LY-83583 (10 microM) had an obvious, albeit variable, inhibitory effect. Basal cyclic GMP content was lower in tissues treated with either compound and rose upon exposure to CO. However, the levels attained were still within the range of values for tissues prior to any treatment. Furthermore, the elevation in cyclic GMP was not related to the magnitude of the CO relaxation. 4. Illumination of the ductus with monochromatic light at 450 nm reversed the CO relaxation and any concomitant increase in cyclic GMP. In the absence of CO, light by itself had no effect. 5. Ductal preparation with only muscle behaved as the intact preparations in reacting to CO, both in the absence and presence of guanylyl cyclase inhibitors, or during illumination. 6. We conclude that the primary action of CO in the ductus arteriosus is not exerted on the guanylyl cyclase heme and that cyclic GMP may only have an accessory role in the relaxation to this agent. This finding reasserts the importance of a cytochrom P450-based mono-oxygenase reaction for generation of tone and as a target for CO in the ductus.

Circulatory adaptation to bimodal respiration in the dipnoan lungfish.

In the dipnoan lungfish, Protopterus aethiopicus, P. annectens, and Lepidosiren paradoxa, the ductus is a short powerful muscular vascular trunk forming a channel for communication between the systemic and pulmonary circulations. In structure, the dipnoan ductus is very similar to the ductus arteriosus (Botalli) in the mammal. Innervation is abundant, consisting of myelinated and nonmyelinated nerve fibers issuing, at least in part, from the vagus. Neurons are present in the adventitia, and numerous nerve profiles, filled with small agranular vesicles, are closely associated with the myocytes, suggesting strong cholinergic control. Perfusion of the ductus in vitro using hypoxic saline causes it to dilate; conversely it is constricted by alpha-agonists. Dopamine and prostaglandin E2 are potent dilators, whereas the beta-agonist, isoproterenol, and acetylcholine are less powerful. A vasomotor segment has been identified on the pulmonary artery (PAVS) close to its junction with the ductus. Its location and structure are similar to the corresponding segment in amphibians and reptiles. It is innervated by endings filled with small clear vesicles. Granular vesicle cells are also present within the adventitia. The PAVS is constricted by acetylcholine. As in amphibians, alpha-agonists and hypoxic saline are without vasomotor effects. Based on the anatomic and physiological observations, a concept of cyclic perfusion of the gas exchangers in Dipnoi is proposed. During the alternation between air breathing (emersion) and apneic phases (immersion), the pattern of the circulation in the lungfish oscillates between that of a tetrapod and a fish.

Further evidence implicating E-type prostaglandins in the patency of the lamb ductus arteriosus.

A blocker of prostaglandin (PG) snythesis, indomethacin, given to pregnant ewes near term produces constriction of the lamb ductus arteriosus in utero. The result supports the hypothesis formulated previously that E-type prostaglandins, which are potent relaxant on the ductus, are responsible for maintaining the patency of the vessel during foetal life.

Morphometric data on the arterial duct in the human fetal heart.

In a total of 496 fetuses and newborns ranging in body weight from 60 to 5000 g, we performed a morphometric study of the ascending aorta, the descending aorta, the aortic isthmus, the right pulmonary artery, the left pulmonary artery and the arterial duct. In all, nine different parameters were measured in each specimen. The variations in the correlations between two measurable characteristics, namely body weight and each of the morphometric parameters, were analyzed. The minimum, normal and maximum patterns of normality for each parameter were obtained with regression equations. We compared statistically the diameter of the arterial duct with the diameter of the ascending and descending aorta, the aortic isthmus, the right pulmonary artery and the left pulmonary artery with one way analysis of variance, using Bonferroni's test in the pairwise comparisons. The diameter of the arterial duct was smaller than the diameter of the ascending and descending aortas, the aortic isthmus, the right pulmonary artery and the left pulmonary artery, and the diameter of the ascending aorta was larger than that of the descending aorta. These morphological data have immediate clinical and surgical applications in the treatment of fetal and perinatal cardiovascular disorders.

Histopathology of the arterial duct (ductus arteriosus) with and without treatment with prostaglandin E1.

In the light of conflicting data in the literature on the relation between histopathology of the arterial duct and treatment with prostaglandin E1, we restudied our material. Special attention was paid to pathology of the duct not influenced by administration of prostaglandin E1. For this reason, three comparison groups (59 specimens) of non-treated ducts were evaluated. The results were compared with data from ducts obtained from 24 infants treated with prostaglandin E1. In agreement with our earlier findings, and with the results of Calder and her colleagues, there is indeed a marked increase in histopathology of the duct after administration of prostaglandin E1. The histopathology itself, however, is not specific for ducts treated with prostaglandin E1. It can also be found in the non-treated material. This has been previously described by others but had not been noted in our own previous work. The essential difference between those studies that confirmed an increase in pathology after treatment with prostaglandin E1 and those failing to find a marked effect is in the method of study. Changes were observed by those, including ourselves, who investigated complete sets of serial sections. The changes were not seen by those studying selected cross-sections from isolated parts of the duct or, at least in the cases treated with prostaglandin E1, sections taken at intervals.

The special status of the pulmonary arch artery in the branchial arch system of the rat.

A renewed study of the development of the branchial arch system was essential in view of the special morphologic characteristics of the ductus arteriosus, which derives from the pulmonary arch artery or sixth branchial arch artery. In congenital heart disease certain aorto-pulmonary collateral arteries have a marked histological similarity to the ductus arteriosus. To gain a better insight into the development of these vessels, 27 rat embryos, with the number of somites ranging between 19 and 41, were studied. Most embryos were collected after shortterm in vitro-culture, allowing precise staging of age and development. The vascular system of these embryos was injected with Indian ink, to enable easy recognition of even the smallest endothelium-lined vessels. The embryos were serially sectioned (3-5 microns) and reconstructed using a graphic method. The results show that the pulmonary arch artery differs from the other arch arteries in that it is the most cranial vessel of a system of ventral splanchnic arteries, which connects the pulmonary plexus with the dorsal aortae at an early stage. With the exception of the pulmonary arch artery, these connections are transient. The pulmonary arteries develop from the remaining parts of the plexus. It is argued that these connections can persist in the human as aorto-pulmonary collaterals, in certain cases with abnormalities in the pulmonary part of the cardiac outflow tract.

Anatomical and sonographic correlation of the fetal ductus arteriosus in first and second trimester pregnancy.

Ultrasonic visualization of the ductus arteriosus in first and second trimester pregnancies was compared with postmortem preparations. Twenty human fetal postmortem specimens from 8 to 19 weeks menstrual age were examined, 11 with microscopic reconstruction, nine with macroscopic dissection. The angle between ductus arteriosus and aortic isthmus (upstream) and ductus arteriosus and descending aorta (downstream) was determined. In 52 normally developing fetuses between 14 and 27 weeks, the angle between the ductus arteriosus and the thoracic spine as visualized in real-time ultrasound was determined. In a further 19 normally developing fetuses between 14 and 25 weeks, ductal blood flow was visualized by colour velocity imaging (CVI). In anatomical preparations, the upstream angle was always less than 90 degrees and the downstream angle was always 80 degrees or more. These angles were unrelated to menstrual age. In both real-time and CVI ultrasound, the angle between ductus arteriosus and thoracic spine remained at approximately 90 degrees. CVI showed highest blood flow velocities at the point of ductal insertion into the aorta. When performing Doppler ultrasound examinations in the fetal ductus arteriosus, no menstrual age dependent angle adjustment appears to be necessary.

Changes in right ventricular volume in early human neonates.

To evaluate changes in the right ventricular volume in early human neonates, twenty fullterm infants were examined at 2, 24 and 120 h of age by two-dimensional echocardiography. End-diastolic and end-systolic right ventricular volumes (RVEDV and RVESV, respectively) were calculated with a computer system based on the bi-plane Simpson's rule using the apical four chamber and parasternal short axis views. Then right ventricular stroke volume (RVSV), ejection fraction (RVEF), and the mean normalized systolic ejection rate were obtained. The inner diameter of the ductus arteriosus was also measured simultaneously. RVEDV increased significantly by 24 h of age, but remained constant thereafter. RVESV remained virtually unchanged from 2 to 120 h, resulting in a significant increase (36%) of RVSV at 24 h compared with that at 2 h. The mean normalized systolic ejection rate remained unchanged. There was a good correlation between RVEDV and RVSV (r = 0.83). All ductus arteriosus except three narrow ones was closed by 24 h of age. In conclusion, at 24 h of age, the significantly increased RVEDV was closely related to the increased RVSV, which might be induced by increased volume load to the right ventricle because of the closure of the ductus arteriosus.