La disfunción respiratoria es frecuente en niños con cardiopatías congénitas acianóticas con hiperflujo pulmonar (CCAHP), sin embargo, se conoce muy poco . Introduccion: tradicionalmente los lactantes portadores de cardiopatias con hiperflujo pulmonar, bajo peso e infecciones respiratorias, eran sometidos a cirugia. Hiperflujo e hipertensión venocapilar pulmonar. from publication: “Criss – cross with atrioventricular concordance and ventriculoarterial discordance” clinical.

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Computed tomography in pulmonary evaluation of children with acyanotic congenital heart defect and pulmonary hyperflow. I ; Mariana Limeira Teixeira, M. Respiratory dysfunction is common in children with acyanotic congenital heart defects ACHD with pulmonary hyperflow; however, little is known about the pulmonary structure of those patients. The objective of this study was to quantify the volumes of air and tissue, as well as the distribution of hipertlujo aeration in this population.


After approval by the Ethics Committee of the institution and signing of an informed consent, seven children with ACHD with pulmonary hyperflow underwent computed tomographies of the chest. All images included the left and right pulmonary contour, and pulmonary volumes and weight were calculated using volumetric data. Paired Student t test was used to compare left and right, and pumonar regression was used for correlations.

Patients had a mean age of 20 months and weight of 9. Total pulmonary volume TPV was The right lung represented The pulmonary volume of air on the right was The volume of lung tissue was greater than expected in children with ACHD with hhiperflujo hyperflow, possibly due to interstitial edema. Pulmonary aeration is reduced in the left lung due to the compression of the lung by the heart. La edad mediana fue de 20 meses y el peso fue de 9,9 kg.


Acyanotic congenital heart defects with pulmonary hyperflow represent a group of congenital cardiopathies characterized by the presence of intracardiac or large vessels malformation that leads arterialized blood after passing through the pulmonary circulation to flow from the left to the right chambers of the heart or pulmonary artery.

Those anomalies in the formation of the heart occur during intra-uterine life and include a large variety of cardiocirculatory malformations, ranging from patent ductus arteriosus to absence of interatrial and interventricular septi. Physiologically, the development of clinical manifestations depends on the magnitude of the flow through the right-left communication and it is essentially translated by the presence of pulmonary congestion of varying degrees and cardiomegaly 1.

A considerable percentage of this population undergoes surgical correction of cardiac defects in the first two years of life to avoid the harmful consequences of persistent hyperflow on the pulmonary circulation. Despite advances on the knowledge of the physiology of pulmonary circulation in this population 2,3little is known on the structure and distribution of air in the pulmonary parenchyma of children with acyanotic congenital cardiopathy with pulmonary hyperflow.

Several reasons hinder the in vivo investigation of the structure and function of the respiratory system in this age group, including the availability of few accurate non-invasive methods, incapacity of patients to cooperate with exams such as pulonar, the need of sedation to perform exams in small children, and the low incidence of this group of disorders in the general population.

In adult patients in different clinical conditions and in experimentation animals hiperrlujo computed tomography allows the quantitative and qualitative evaluation of pulmonary changes using volumes and X-ray attenuation by the pulmonary parenchyma 4,5.

The objective of this study was to evaluate the pulmonary structure quantifying the volume and weight of the lungs as well as the distribution of air in the pulmonary parenchyma using helical computed tomography of the chest in children with acyanotic congenital cardiopathy without clinical pulmonary edema, ages 6 months to 2 years, and with indication of surgical treatment. This study is part of a research project that investigates the impact of cardiac surgery and mechanical ventilation on the pulmonary physiology of children with acyanotic congenital cardiopathy with pulmonary hyperflow and discusses aspects related to preoperative pulmonary changes.

Inclusion criteria were as follows: On the day before the surgery, after the evaluation of inclusion and exclusion criteria, patients were transported by pumlonar physicians to the department of imaging diagnosis for a computed tomography. Since patients were unable to follow commands for apnea, the test was done during spontaneous breathing after the children get used to the environment. To prevent accidents, patients were immobilized on the tomography table with Velcro straps over their head, on the hips and lower limbs with the necessary tension to avoid movements and a physician properly protected against radiation remained in the tomography room during the exam.

This restriction minimized artifacts caused by movements during the hi;erflujo seconds necessary for image acquisition. During transportation and the exam, patients were monitored with continuous cardioscopy, pulse oximetry, and non-invasive blood pressure using oulmonar transport Philips M3 monitor Philips, Eindhoven, Netherlands.


Exposures were done at kV and mAs, using a one-second rotation time, mm collimation, and pitch of one. Continuous axial images were reconstructed from the volumetric data using the reconstruction hipertlujo of the CT equipment, with 5-mm width.

The pulmonary volume was computed adding the total number of voxels elemental volume unit of computed tomography whose dimensions were known in all areas of pulmonary delineation in different contiguous images.

The volumes of air and tissue were measured according to the method described by Puybasset et al.

The attenuation coefficient CT coefficient of each voxel is defined as the attenuation coefficient of X-rays crossing the study material minus the water attenuation coefficient divided by the water attenuation coefficient and expressed in Hounsfield units HU. Using this analysis, it is possible to compute the volume of air and tissue present in the lung. For each compartment with known number of voxels the pylmonar volume, volume of air, tissue volume, and the weight of the pulmonary parenchyma were computed using the following formulas: On the second step, total volume, air volume, and tissue volume, and hipefrlujo weight of the pulmonary parenchyma of a specific area of interest were computed by adding the respective volume and weight of the compartments analyzed in the different hiprflujo of interest.

The tissue volume measured by pulmmonar CT represents the summation of the volumes of the pulmonary parenchyma, blood and its cellular components, and pulmonary extravascular water.

Parallel to the determination of the volumes of air and pulmonary tissue, computed tomography allows the study of the pulmonary parenchyma as a function of the degree of aeration.

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In this analysis, the pulmonary parenchyma is classified according to the CT coefficient in: Anthropometric data and those related to the total results of both lungs were expressed descriptively. Since the weight of the patients varied the data on the volumes of pulmonary air and tissue and the weight of pulmonary compartments according to the degree of aeration were presented as a fraction of the total volume and weight, respectively. The normal distribution of all parameters measured in this study was tested by the Kolmogorov-Smirnov test.

Paired Student t test or Wilcoxon test were used to compare the left and right lungs. Regression curves were adjusted using an exponential model. Seven children with acyanotic congenital cardiopathy with pulmonary hyperflow with mean age of 20 months ranging from 6 to 24 monthsand mean weight 9. Table I shows individual anthropometric data and the diagnosis of the patients included in the study.

All CT scans were done without intercurrences. Figure 1 shows a representative CT scan of the chest of a child with congenital cardiopathy with pulmonary hyperflow. As can be seen on the left panel of Figure 2the mean total lung volume was When tissue and air were considered as a fraction of the total lung volume, it was observed that they represented The mean weight of the pulmonary parenchyma was When the pulmonary parenchyma was analyzed in relation to the distribution of aeration, it was observed that the non-aerated pulmonary parenchyma represented 9.

Figure 4 shows the volume and weight of the right and left lungs in relation to the total values of both lungs. On the left panel, one observes that the right lung represented As for the total tissue volume, the right lung represented The right panel of figure 4 shows that the fraction of pulmonary parenchyma classified according to the degree of aeration in relation to the total weight of the parenchyma are compared between the right and left lungs.

Children with acyanotic congenital cardiopathy and pulmonary hyperflow have left-to-right shunt with mixture of arterial blood from the systemic circulation with the venous blood from the pulmonary circulation. Understanding this clinical situation depends on the knowledge of the fetal circulation and that of the postnatal transition. In intrauterine life the presence of the foramen ovale and ductus arteriosus associated to the elevated pressure in the pulmonary vascular bed and the low systemic resistance due to the placenta favors the distribution of the blood flow through the systemic circulation and only a small fraction of blood flows through the pulmonary arteries to the left atrium.

In general, one third of the total blood volume of a child flows to the left atrium through the foramen ovale, while the remaining two thirds flow to pulmonra pulmonary artery. In normal conditions, after pulmonxr with the occlusion of the umbilical cord and pulmonary expansion, vasodilation and reduction in vascular resistance is seen in the pulmonary circulation with the consequent increase in pulmonary blood flow and in venous pulmonary pressure.


The increase in the volume of blood returning to the left atrium and consequent increase in the pressure in this chamber leads to the functional closure of the foramen ovale a few hours after birth.

The increase in pulmoar pressure hipefflujo oxygen leads to vasoconstriction of the ductus arteriosus and eventual closure in the first three to four weeks of life. In children with acyanotic congenital cardiopathy the foramen ovale and ductus arteriosus remain patent, or the defects in the interatrial septum, interventricular septum, or atrioventricular septum are not closed perpetuating the fetal circulation described 3,8.

The pathophysiological changes hierflujo on the size of the shunt frequently causing respiratory complications related to interstitial-alveolar edema. The increase in the volume of water in the extravascular space of the lungs is hiperfljuo to the increase in pulmonary blood flow associated with varying degrees of congestive heart failure due to the interdependence of both ventricles 9.

Using a combination of chest CT and helium dilution pulmoar, Gattinoni et al.

Unfortunately, it is impossible to separate the blood and pulmonary extravascular water components. When the pulmonary parenchyma of the children was evaluated according to the degree of aeration, it was observed that non-aerated pulmonary parenchyma represented 9. As mentioned before, studies investigating the pulmonary parenchyma of children without cardiorespiratory diseases with computed tomography are lacking; however, Vieira et al.

Due to the increase in circulating blood inside the lungs and consequent increase in the caliber of the pulmonary vessels secondary to pulmonary hyper-flow, an increase in non-aerated pulmonary parenchyma is expected, since voxels that characterize blood, liquid elements, and vascular structures have a CT coefficient close to zero.

On the other hand, despite normal peripheral saturation of hemoglobin, a considerable fraction of the pulmonary parenchyma was poorly aerated. This compartment of the pulmonary parenchyma is probably increased due to interstitial edema and increase in the volume of blood in pulmonary capillaries, but maintaining the aeration of the alveoli and small airways.

Those results are similar to those observed in other populations of patients and they are justified by the position of mediastinal structures that are located, mainly, in the left hemithorax.

In some patients with acute respiratory distress syndrome, Malbouisson et al. Several authors described the compression of the left lower lobe and pulmonary artery induced by cardiomegaly This phenomenon, associated with hiperflijo muscular relaxation caused by anesthetic agents, is responsible for the frequent atelectasis formation in the left lower lobe in children undergoing surgeries to correct congenital cardiopathies 18, This study has some limitations.

Technically, it should be emphasized that it was not possible to control the moment of the respiratory cycle when tomographic images were acquired because children of this age group cannot follow complex verbal commands. Thus, it was not possible to compare the measurements of specific respiratory parameters such as functional residual capacity FRC with levels predicted by formulas, like those proposed by Stokes and Hipwrflujo 20 and determine the impact of the cardiopathy on FRC.

The absence of a hiperflujk group is another important factor, since one pulmlnar justify performing CT scans in children without cardiopulmonary disorders. One should not hiperfljuo that the growth and developmental processes of the pulmonary parenchyma continue until the age of 8 years, and during this period an important increase in the number of alveoli is seen This would explain the proportion of pulmonary volume in relation to the body weight, such as the correlations reported here, since the efficiency of gas exchange in this organ increases in the first years of life allowing the reduction of its mass in relation to the body weight.

To conclude, children with acyanotic congenital cardiopathy with pulmonary hyperflow have an increase in the volume of pulmonary hiperfljjo greater than expected in normal conditions. It also has been accurately recorded that the volume of air in the left lung is proportionally smaller than in the right lung due to the compression exerted by the heart, whose size is increased, and other mediastinal structures.

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