Prevalence, economic assessment, and risk factors of gastrointestinal nematodes infecting herds in tropical, dry and temperate climate regions in Mexico.

This study investigated exposure to gastrointestinal (GI) nematodes on dairy cattle farms by antibody level determination in bulk tank milk (BTM) samples and its influence on production to detect the risk factors for infection in different climate regions in three states of Mexico. From January to April 2017, BTM samples were collected from 1058 dairy cattle herds and used to establish three Köppen climate classes (tropical, dry and temperate) and states of Mexico. A questionnaire on farm management was applied. The overall herd prevalence of parasites was 67.20%. The highest percentage of positive herds was detected in Veracruz state (78.45%). In addition, the highest prevalence among the climate regions was found in the tropical climate (78.59%). In general, production losses were approximately 1.37-1.78 kg of milk/cow per day. The annual costs of milk production losses per farm were estimated for three different climate regions, ranging between $5541.49 and 6982.50 US$, and those in the three states varied between 5974.10 and 8660.06 US$. The costs for anthelmintic treatments for young stock and adult cows ranged between 57.51 and 192.75 US$, respectively, among the three climate regions and between 46.02 and 189.49 US$, respectively, among the three states. The overall annual costs of milk yield loss per cow were estimated to be 150.74 US$ for the climate regions and 190.54 US$ for the three states of Mexico, followed by the treatment costs for young stock (4.02 US$) and adult cows (3.99 US$). The results suggest that the economic losses due to GI nematodes in Mexican dairy herds are approximately 248 million US$ per annum. Four final models were built based on multivariate logistic regression for potential statistical association from the ELISA results using climatic/environmental and management factors so that each model used different risk factors that were significantly associated with helminth infections in dairy herds.

Bulk tank milk ELISA to detect IgG1 prevalence and clustering to determine spatial distribution and risk factors of Fasciola hepatica-infected herds in Mexico.

Fasciola hepatica is a helminth parasite that causes huge economic losses to the livestock industry worldwide. Fasciolosis is an emerging foodborne zoonotic disease that affects both humans and grazing animals. This study investigated the associations between climatic/environmental factors (derived from satellite data) and management factors affecting the spatial distribution of this liver fluke in cattle herds across different climate zones in three Mexican states. A bulk-tank milk (BTM) IgG1 enzyme-linked immunosorbent assay (ELISA) test was used to detect F. hepatica infection levels of 717 cattle herds between January and April 2015. Management data were collected from the farms by questionnaire. The parasite's overall herd prevalence and mean optical density ratio (ODR) were 62.76% and 0.67, respectively. The presence of clustered F. hepatica infections was studied using the spatial scan statistic. Three marked clusters in the spatial distribution of the parasite were observed. Logistic regression was used to test three models of potential statistical association from the ELISA results using climatic, environmental and management variables. The final model based on climatic/environmental and management variables included the following factors: rainfall, elevation, proportion of grazed grass in the diet, contact with other herds, herd size, parasite control use and education level as significant predictors. Geostatistical kriging was applied to generate a risk map for the presence of parasites in dairy herds in Mexico. In conclusion, the spatial distribution of F. hepatica in Mexican cattle herds is influenced by multifactorial effects and should be considered in developing regionally adapted control measures.

Detection of tick-borne Anaplasma bovis, Anaplasma phagocytophilum and Anaplasma centrale in Spain.

The genus Anaplasma (Rickettsiales: Anaplasmataceae) includes species of medical and veterinary importance. The presence of Anaplasma spp. in ticks from birds, as well as in Haemaphysalis punctata (Ixodida: Ixodidae) specimens collected from cattle and vegetation in northern Spain was investigated. A total of 336 ticks from birds [174 Ixodes frontalis (Ixodida: Ixodidae), 108 H. punctata, 34 Hyalomma marginatum (Ixodida: Ixodidae), 17 Ixodes ricinus (Ixodida: Ixodidae) and three Ixodes spp.], and 181 H. punctata specimens collected from cattle (n = 71) and vegetation (n = 110) were analysed. Anaplasma bovis was detected in five H. punctata, including two from birds (1.9%) and three from vegetation (2.7%). Four I. frontalis (2.3%) (one co-infected with 'Candidatus Midichloria mitochondrii') and one I. ricinus (5.9%) removed from birds, as well as four H. punctata (5.6%) collected from cattle showed Anaplasma phagocytophilum infection. In addition, Anaplasma centrale was found in two H. punctata, one from a cow (1.4%) and the other from vegetation (0.9%). This study represents the first evidence of the presence of A. bovis in European ticks, and reports the first detection of A. bovis and A. centrale in H. punctata, and the first finding of A. phagocytophilum and 'Ca. Midichloria mitochondrii' in I. frontalis.

Motility of Fasciola hepatica miracidia assessed with a computer-assisted sperm analyser.

The motility parameters of Fasciola hepatica miracidia were assessed at different temperatures and times post-hatching using computer-assisted sperm analysis. Eggs were incubated at 22 °C or 25 °C for 14 days. Five motion parameters were evaluated at different incubation temperatures up to 10 h post-hatching. No differences were observed in the percentage that hatched after incubation at the two different temperatures. However, the straight-line velocity of miracidia following incubation at 22 °C was significantly different from that observed at 25 °C (P< 0.01). All miracidium motion parameters at different post-hatching temperatures showed an overall decrease at the end of the experiment. Those miracidia hatching from eggs incubated at 25 °C had a higher velocity of 1673.3 µm/s compared with 1553.3 µm/s at 22 °C. Velocity parameters increased as the post-hatching temperature increased from 22 °C to 37 °C.

FSI Analysis of a healthy and a stenotic human trachea under impedance-based boundary conditions.

In this work, a fluid-solid interaction (FSI) analysis of a healthy and a stenotic human trachea was studied to evaluate flow patterns, wall stresses, and deformations under physiological and pathological conditions. The two analyzed tracheal geometries, which include the first bifurcation after the carina, were obtained from computed tomography images of healthy and diseased patients, respectively. A finite element-based commercial software code was used to perform the simulations. The tracheal wall was modeled as a fiber reinforced hyperelastic solid material in which the anisotropy due to the orientation of the fibers was introduced. Impedance-based pressure waveforms were computed using a method developed for the cardiovascular system, where the resistance of the respiratory system was calculated taking into account the entire bronchial tree, modeled as binary fractal network. Intratracheal flow patterns and tracheal wall deformation were analyzed under different scenarios. The simulations show the possibility of predicting, with FSI computations, flow and wall behavior for healthy and pathological tracheas. The computational modeling procedure presented herein can be a useful tool capable of evaluating quantities that cannot be assessed in vivo, such as wall stresses, pressure drop, and flow patterns, and to derive parameters that could help clinical decisions and improve surgical outcomes.

FSI analysis of a human trachea before and after prosthesis implantation.

In this work we analyzed the response of a stenotic trachea after a stent implantation. An endotracheal stent is the common treatment for tracheal diseases such as stenosis, chronic cough, or dispnoea episodes. Medical treatment and surgical techniques are still challenging due to the difficulties in overcoming potential complications after prosthesis implantation. A finite element model of a diseased and stented trachea was developed starting from a patient specific computerized tomography (CT) scan. The tracheal wall was modeled as a fiber reinforced hyperelastic material in which we modeled the anisotropy due to the orientation of the collagen fibers. Deformations of the tracheal cartilage rings and of the muscular membrane, as well as the maximum principal stresses, are analyzed using a fluid solid interaction (FSI) approach. For this reason, as boundary conditions, impedance-based pressure waveforms were computed modeling the nonreconstructed vessels as a binary fractal network. The results showed that the presence of the stent prevents tracheal muscle deflections and indicated a local recirculatory flow on the stent top surface which may play a role in the process of mucous accumulation. The present work gives new insight into clinical procedures, predicting their mechanical consequences. This tool could be used in the future as preoperative planning software to help the thoracic surgeons in deciding the optimal prosthesis type as well as its size and positioning.

Copper and lead exposures disturb reproductive features of primary endometrial stromal and epithelial cells.

This study investigates if Cu and Pb act as endocrine disruptors affecting endometrial cells. Primary EnSCs and EnECs were exposed to Cu (0, 50, 100 and 200 µM) or Pb (0, 30, 100 and 500 µM) and assessed for viability, decidualization, apoptosis and proliferation on EnSCs, and wound healing and adhesion capabilities on EnECs. Cu exposure decreased significantly cell viability in a dose-dependent manner. Cu and Pb negatively affected in vitro decidualization, showing a significant decrease in PRL secretion. HOXA10 and ERα mRNA levels significantly decreased in decidualized cells (dEnSCs) exposed to Cu. Cu and Pb decreased adhesion and regeneration capability in EnEC. This study reveals that Cu and Pb could negatively affect endometrial functionality, compromising the decidualization process and disrupting endometrial regeneration and embryo adhesion. Therefore, special care should be taken considering heavy metals exposure if pregnancy is being pursued.

An accurate finite element model of the cervical spine under quasi-static loading.

Cervical disc injury due to impact has been observed in clinical and biomechanical investigations; however, there is a lack of data that helps to elucidate the mechanisms of disc injury during these collisions. Therefore, it is necessary to understand the behavior of the cervical spine under different types of loading situations. A three dimensional finite element (FE) model for the multi-level cervical spine segment (C0-C7) was developed using computed tomography (CT) data and applied to study the internal stresses and strains of the intervertebral discs under quasi-static loading conditions. The intervertebral discs were treated as nonlinear, anisotropic and incompressible subjected to large deformations. The model accuracy was validated by comparing it with previously published experimental and numerical results for different movements. It was shown that the use of a fiber reinforced model to describe the behavior of the annulus of the discs would predict higher maximum shear strains than an isotropic one, being therefore important the use of complex constitutive models in order to be able to detect the appearance of injured zones, since those strains and stresses are supposed to be related with damage to soft tissues. Several movements were analyzed: flexion, extension and axial rotation, obtaining that the maximum shear stresses in the disc were higher for a flexo-extension movement.

An experimental study of the mouse skin behaviour: damage and inelastic aspects.

Samples of male and female mice skin were tested under monotonic and cyclic loading to mechanically characterize the tissue for large deformations. Cyclic tests have shown a typical Mullins effect widely known for elastomers and other soft tissues. No statistical difference was found in the maximum stretch of the sample after the fifth loading cycle for male (1.26 +/- 0.035) and female (1.18 +/- 0.083). However, larger dispersion was obtained for the maximum stress for both genders, 0.61 +/- 0.16 MPa for male and 0.78 +/- 0.32 MPa for female. Results show the presence of inelastic strain and stress softening in the skin at large deformations. They also have shown how stress softening and residual strain change with the magnitude of the applied load. Good correlation was observed between the residual strain and the maximum strain previously attained by the sample during loading for all samples. However, the correlation was different between genders.

Dynamic 3D FE modelling of the human temporomandibular joint during whiplash.

Rear-end impacts account for more than one-third of vehicle accidents, and nearly 40% of these accidents produce whiplash injuries. Whiplash injury to the neck has often been considered a significant risk factor for the development of temporomandibular disorders (TMD). The objective of this study was to simulate the dynamic response of the temporomandibular joint during two types of impacts: a rear end and a frontal impact. To understand the dynamic forces acting on the joint, we extended a previous human temporomandibular joint model and analyzed the stress distributions in the soft elements of the joint. In the rear-end impact, it could be appreciated that the inertia of the mandible caused it to move posteriorly slower than the head, and this resulted in downward and forward displacements of the disc-condyle complex relative to the cranial base. Consequently, a rapid and big mouth opening occurs. In contrast, during the frontal impact, the mouth hardly opened, because the superior maxilla pushed the mandible to move together. There was not differential movement between bony components of the joint and therefore the soft tissues of the joint were not subjected to high loads. From these results, and despite the limitations of the simulations performed, we could conclude that neither a rear-end impact at low-velocity nor a frontal impact would produce damage to the soft tissues of the joint.

A finite element model to accurately predict real deformations of the breast.

Most surgical procedures in breast plastic surgery are either reconstructive procedures following oncologic interventions (tumorectomy, quadrantectomy, mastectomy ...) or aesthetic ones, both augmentation and reduction. With current techniques, the results of such procedures cannot be fully guaranteed. Usually, surgical planning is based on a photographic and anthropometric study of the breast only. Among others, one of the difficulties that the plastic surgeons have is the noticeable change of the breast shape with the position of the patient. Thus, it is more and more necessary to plan a presurgical methodology to help the plastic surgeon and guarantee the patient a successful result of the intervention. In order to establish a reliable simulation method that could predict a patient-specific outcome after breast surgery, this study started trying to correlate spatial features of the breast between lying and standing up positions. A biomechanical model of breast was proposed and implemented into a finite element context to predict deformations, and from these the breast shape in different positions. The resulting shapes were compared with multimodal images, whereas the breast surface displacements were compared with manually identified landmarks and 3D scanner images. From the results, it can be concluded that the model hereby presented reasonably approximates breast response to gravity forces, therefore providing accurate and useful information to the surgeon planning such surgical procedures.

'Candidatus Neoehrlichia mikurensis' in Europe.

'Candidatus Neoehrlichia mikurensis' is an uncultured emerging bacterium that is provisionally included in the family Anaplasmataceae. In Europe, it is transmitted by Ixodes ricinus ticks. Rodents are the reservoirs. It is widely distributed in mammals (both wild and domestic) and birds. It causes an inflammatory disease in humans with underlying diseases, but the microorganism also affects immunocompetent individuals in which asymptomatic infection has been recognized. A high degree of suspicion and the use of molecular tools are needed for the correct diagnosis. Efforts to cultivate it and to investigate its pathogenesis should be a priority.

Isolation of Rickettsia amblyommatis in HUVEC line.

Rickettsia amblyommatis, formerly named Rickettsia amblyommii and 'Candidatus Rickettsia amblyommii' is an intracellular bacterium belonging to the spotted fever group Rickettsia. It is highly prevalent in Amblyomma americanum and in other Amblyomma spp. throughout the Western Hemisphere. R. amblyommatis has been cultivated in chicken fibroblast, primary embryonated chicken eggs, Vero cells and arthropod-derived cells. Because of the affinity of rickettsiae to invade vascular endothelial cells, we tried to isolate R. amblyommatis from a nymph of Amblyomma cajennense s.l. collected in Saltillo (Coahulia, Mexico) using human umbilical vein endothelial cells (HUVEC). One tick half was analysed by ompA PCR and was found to be positive for R. amblyommatis. The other half was selected for in vitro culture of Rickettsia spp. It was triturated in 1 mL of endothelial cell growth medium with 1% antibiotic-antimycotic solution, and the homogenate was inoculated into a HUVEC line. Culture was maintained at 33°C in endothelial cell growth medium plus 2 mM l-glutamine and 2% fetal calf serum, with 5% CO2. The medium was changed weekly. Culture was checked by Gimenez stain for Rickettsia-like intracellular organisms. After 48 days of incubation, Rickettsia-like organisms were observed in HUVEC. PCR assays and sequencing of ompA gene in the culture suspension showed 100% identity with R. amblyommatis. This isolate was successfully established in HUVEC, and it has been deposited in the collection of the Center of Rickettsioses and Arthropod-Borne Diseases, Infectious Diseases Department, Hospital San Pedro-Center of Biomedical Research from La Rioja, Logroño, Spain. The HUVEC line is a useful tool for the isolation of R. amblyommatis.

Approach towards the porous fibrous structure of the periodontal ligament using micro-computerized tomography and finite element analysis.

The periodontal ligament (PDL) is a porous and fibrous soft tissue situated around the tooth, which plays a key role in the transmission of loads from the tooth to the alveolar bone of the mandible. Although several studies have tried to characterize its mechanical properties, the behaviour of this tissue is not clear yet. In this study, a new simulation methodology based on a material model which considers the contribution of porous and fibrous structure with different material model formulations depending on the effort direction is proposed. The defined material model was characterized by a non-linear approximation of the porous fibrous matrix to experimental results obtained from samples of similar species and was validated by rigorous test simulations under tensile and compressive loads. The global PDL response was also validated using the parameters of the characterization in a finite element model of full human canine tooth obtained by micro-tomography. The results suggest that the porous contribution has high influence during compression because the bulk modulus of the material depends on the ability of interstitial fluid to drain. On the other hand, the collagen fibres running along the load direction are the main responsible of the ligament stiffness during tensile efforts. Thus, a material model with distinct responses depending of the load direction is proposed. Furthermore, the results suggest the importance of considering 3D finite element models based of the real morphology of human PDL for representing the irregular stress distribution caused by the coupling of complex material models and irregular morphologies.

An accurate simulation model of anteriorly displaced TMJ discs with and without reduction.

Internal derangement of the temporomandibular joint (TMJ) is defined as an abnormal positional relationship of the disc relative to the mandibular condyle and the glenoid fossa. Among others, the anterior disc displacement is the most common disorder, however its origin and consequences are still unclear. Several finite element simulations of the TMJ have been developed, but none of them has reported dynamic simulations of the disc as a three-dimensional, fiber-reinforced biphasic material under finite deformations, during the opening movement of a pathologic joint affected of an anterior displacement of the disc with and without reduction, using a realistic geometry of the ligaments in the joint. The aim of the work presented here was to compare the stress distribution in the healthy joint and in two pathologic situations, one joint affected of an anterior disc displacement with reduction (ADDWR) and one without reduction (ADDWOR) during an opening movement of the mouth. It was found that, while in the healthy disc the highest compressive stresses were located in the intermediate zone, in the pathologic joints the maximum compressive stresses were located in the posterior band both in the ADDWOR case and in the ADDWR before the reduction. Moreover, although the final stress distribution in the ADDWR was similar to that in the healthy case, the collateral ligaments supported higher stresses, a fact that could lead to degeneration of these components and subsequently to the total anterior displacement of the disc. Finally, the results suggest that an anterior displacement of the disc would lead to higher compressive and tangential stresses in the posterior band of the disc than in the healthy one, and as a consequence, to possible perforations in that zone of the disc which would modify its geometry if no treatment is applied.

A comparative test of ixodid tick identification by a network of European researchers.

This study reports the results of a comparative test of identification of ticks occurring in Western Europe and Northern Africa. A total of 14 laboratories were voluntarily enrolled in the test. Each participant received between 22 and 25 specimens of adult and nymphal ticks of 11 species: Dermacentor marginatus, D. reticulatus, Haemaphysalis punctata, Hyalomma lusitanicum, Hy. marginatum, Ixodes ricinus, I. hexagonus, Rhipicephalus annulatus, R. bursa, R. rossicus, and/or R. sanguineus s.l. Ticks were morphologically identified by three of the co-authors and the identification confirmed by a fourth co-author who used molecular methods based on several genes. Then ticks were randomly selected and blindly distributed among participants, together with a questionnaire. Only specimens collected while questing and, if possible, in the same survey, were circulated. Because of the random nature of the test, a participant could receive several specimens of the same species. Species in the different genera had variable misidentification rates (MR) of 7% (Dermacentor), 14% (Ixodes), 19% (Haemaphysalis), 36% (Hyalomma), and 54% (Rhipicephalus). Within genera, the MR was also variable ranging from 5.4% for I. ricinus or 7.4% for D. marginatus or D. reticulatus to 100% for R. rossicus. The test provided a total misidentification rate of 29.6% of the species of ticks. There are no significant differences in MR according to the sex of the tick. Participants were requested to perform a second round of identifications on the same set of ticks, using only purposely prepared keys (without illustrations), circulated to the enrolled participants, including 2 species of the genus Dermacentor, 8 of Haemaphysalis, 10 of Hyalomma, 23 of Ixodes, and 6 of Rhipicephalus. The average MR in the second round was 28%: 0% (Dermacentor), 33% (Haemaphysalis), 30% (Hyalomma) 18% (Ixodes), and 50% (Rhipicephalus). Species which are not reported in the countries of a participating laboratory had always highest MR, i.e. purely Mediterranean species had highest MR by laboratories in Central and Northern Europe. Participants expressed their concerns about a correct identification for almost 50% of the ticks of the genera Hyalomma and Rhipicephalus. The results revealed less than total confidence in identifying the most prominent species of ticks in the Western Palearctic, and underpin the need for reference libraries for specialists involved in this task. Results also showed that a combination of certain genes may adequately identify the target species of ticks.

Finite element analysis of the temporomandibular joint during lateral excursions of the mandible.

One of the most significant characteristics of the temporomandibular joint (TMJ) is that it is in fact composed of two joints. Several finite element simulations of the TMJ have been developed but none of them analysed the different responses of its two sides during nonsymmetrical movement. In this paper, a lateral excursion of the mandible was introduced and the biomechanical behaviour of both sides was studied. A three-dimensional finite element model of the joint comprising the bone components, both articular discs, and the temporomandibular ligaments was used. A fibre-reinforced porohyperelastic model was introduced to simulate the behaviour of the articular discs, taking into account the orientation of the fibres in each zone of these cartilage components. The mandible movement during its lateral excursion was introduced as the loading condition in the analysis. As a consequence of the movement asymmetry, the discs were subjected to different load distributions. It was observed that the maximal shear stresses were located in the lateral zone of both discs and that the lateral attachment of the ipsilateral condyle-disc complex suffered a large distortion, due to the compression of this disc against the inferior surface of the temporal bone. These results may be related with possible consequences of a common disorder called bruxism. Although it would be necessary to perform an exhaustive analysis of this disorder, including the contact forces between the teeth during grinding, it could be suggested that a continuous lateral movement of the jaw may lead to perforations of both discs in their lateral part and may damage the lateral attachments of the disc to the condyle.

The effect of collagen reinforcement in the behaviour of the temporomandibular joint disc.

In this paper, the influence of collagen fibres in the behaviour of the temporomandibular joint disc is studied. A three-dimensional finite element model of the joint is developed from a set of medical images. The model comprises the mandible, part of the cranium and both temporomandibular joints. Joints have been considered to be composed of the articular discs and the temporomandibular ligaments. A fibre-reinforced porohyperelastic model was used to study the response under clenching of the fibrocartilage that composes the articular disc. This was divided in an intermediate zone, and two bands, an anterior and other posterior, in order to define the orientation of collagen fibres. The study demonstrates that the introduction of collagen fibres in the biphasic behaviour of the articular disc implies for a prescribed displacement not only an increase of the pressurization in the tissue, but also higher stresses in the anterior and posterior bands, as well as in the lateral zone of the disc. Thus, modelling the disc as an isotropic solid matrix leads in this case to an overestimation of the stresses in the intermediate zone, an underestimation of the pore pressure in this area, and an underestimation of the stresses in the rest of the disc.

Right ventricular ischemia in patients with primary pulmonary hypertension.

OBJECTIVES: The goal of this study was to determine whether right ventricular (RV) ischemia is a contributory factor in the development of RV dysfunction in patients with primary pulmonary hypertension (PPH). BACKGROUND: Patients with advanced PPH develop RV dysfunction, characterized by a decreased cardiac output, increased right atrial pressure (RAP) and/or elevated RV end-diastolic pressure, which progresses to heart failure and death. The cause of this dysfunction is unknown. Right ventricular ischemia may play a role in its development. METHODS: From 1992 to 1999, a prospective study involving 23 patients with PPH at the Instituto Nacional de Cardiologia "Ignacio Chavez" (Mexico City, Mexico) was undertaken. These patients were evaluated clinically and further studied by echocardiography, right heart catheterization and stress myocardial scintigraphy using technetium 99m sestamibi. RESULTS: Nine patients of 23 were found to have scintigraphic images consistent with RV ischemia. Significant correlation was found between RV ischemia obtained through myocardial perfusion scintigraphy and elevation of RV end-diastolic pressure (p < 0.001), elevation of RAP (p < 0.037) and a decrease in mixed venous oxygen saturation (p < 0.0001). No other clinical or hemodynamic variables showed a significant correlation with RV ischemia. CONCLUSIONS: A direct correlation exists between RV ischemia, as determined by myocardial scintigraphy, and hemodynamic alterations suggestive of RV dysfunction in patients with PPH.

Primary pulmonary hypertension in children: clinical characterization and survival.

OBJECTIVES: This study characterized mortality in a group of Mexican children (n = 18, mean [+/- SD] age 9.9 +/- 3 years) with primary pulmonary hypertension and investigated the factors associated with their survival. BACKGROUND: Primary pulmonary hypertension is a progressive, fatal disease of unknown cause. Establishing the diagnosis earlier in life may influence prognosis. METHODS: A dynamic cohort of children with primary pulmonary hypertension were enrolled between December 1977 and May 1991 and followed up through September 1992. Measurements included hemodynamic and pulmonary function variables in addition to demographic data, medical history and response to vasodilator treatment. We also compared the survival estimates of these children with those of our adult patients with primary pulmonary hypertension (n = 42, mean age 27.9 +/- 8.5 years). RESULTS: Baseline mean (+/- SD) pulmonary artery pressure was similar in children and adults (66 +/- 15 vs. 65 +/- 18 mm Hg, p = NS), but a higher cardiac index resulted in a lower mean pulmonary vascular resistance index in children (18 +/- 7 vs. 26 +/- 12 U/m2, p < 0.01). The proportion of patients who had a positive hemodynamic response to vasodilator treatment was higher in children than in adults (41% vs. 25%). Estimated median survival in children was 4.12 years (95% confidence interval [CI] 0.75 to 8.66) and 3.12 years in adults (95% CI 0.5 to 13.25, chi-square log-rank 0.81, p = NS). Elevated right atrial pressure (rate ratio 10.2) and decreased stroke volume index (rate ratio 32.9) were the only significant predictors of mortality (Cox proportional hazards model). CONCLUSIONS: Children with primary pulmonary hypertension have a poor survival expectancy, which does not appear to differ from that in adults with primary pulmonary hypertension. Mortality in childhood primary pulmonary hypertension is also associated with variables that assess right ventricular dysfunction.