Main Pulmonary Artery Branches Research Articles

Frequency of various cardiac complications in children with repaired tetralogy of Fallot identified by computer tomography

BACKGROUND: Tetralogy of Fallot represents 710% of all cases of congenital heart disease, as it occurs in approximately 0.5 per 1,000 live births and is the second most common form of complex congenital heart disease. Advances in diagnosis, surgical techniques, and postoperative treatment have led to an increasing number of patients reaching adulthood, with a dramatic increase in the survival rate to almost 90% at 30 years, thereby creating a need for long-term monitoring of certain anatomic parameters to identify complications in a timely manner. This study aimed to investigate the frequency of computed tomography detected complications after radical correction of Tetralogy of Fallot in pediatric patients.
 AIM: to identify markers between the most frequency computed tomography detected complications after repair of Tetralogy of Fallot in pediatric patients.
 MATERIALS AND METHODS: A retrospective analysis was conducted on 613 patients with Tetralogy of Fallot from October 2011 to June 2020. The study included a total of 116 patients (69 men and 47 women) who experienced complications after a repair of Tetralogy of Fallot, as identified by computed tomography. At the time of repair of Tetralogy of Fallot, the patients average age ranged from 10 to 36 months (mean: 12 months), average body weight was 21 kg, average height was 105.4 cm, and average body surface area was 0.74 m2. The patients median age at the time of the computed tomography examination was 17.5 years (age range: 736 years).
 RESULTS: Among the 116 patients who exhibited complications after an repair of Tetralogy of Fallot, 49 had a pulmonary artery stenosis, 92 had a pulmonary artery branch stenosis (56 of them of the left main pulmonary artery branch, and 36 of them of the right main pulmonary artery branch), 8 had a right ventricular outflow tract stenosis, 32 had a ventricular septal defect, 1 had a shunt thrombosis, 12 had a postoperative deformation of the pulmonary artery, 10 exhibited a marked right ventricular dilatation, 2 had an right ventricular outflow tract aneurysm, and 6 suffered from conduit calcification and stenosis. Moreover, patients with left main pulmonary artery branch stenosis had a 6.5 times greater chance of developing an right main pulmonary artery branch stenosis in (p 0.001).
 CONCLUSION: The most frequently computed tomography detected complications after a repair of Tetralogy of Fallot were pulmonary artery stenosis and pulmonary artery branch stenosis. Patients with pulmonary artery stenosis and pulmonary artery branch stenosis exhibit no significant differences in terms of age, anthropometric parameters (height, weight, and body surface area), and gender distribution in the presence or absence of different stenosis types (pulmonary artery, right main pulmonary artery branch, or left main pulmonary artery branch). However, an right main pulmonary artery branch stenosis increases the chances of developing an left main pulmonary artery branch stenosis.

Electrical stimulation mapping of the pulmonary artery in swine: impact on pulmonary artery denervation procedure for pulmonary hypertension

Abstract Introduction Pulmonary artery denervation (PAD) has been recently shown to decrease pulmonary artery (PA) pressure. However, there is a lack of data related to target sites for ablation. Purpose To determine the optimal PA ablation sites based on response to high-frequency stimulation mapping and anatomical areas where radiofrequency ablation (RFA) should be avoided due to the risk of severe collateral damage. Methods A total of 17 Landrace swines were included into the study. PA angiography, hemodynamic measurements by right heart-sided catheterization and electrophysiological mapping (EM) using low (cycle length 330 ms) and high-frequency (33Hz) stimulation (HFS). Stimulation was performed at PA bifurcation and proximal parts of the main PA branches with a 5-mm distance between points; catheter manipulation was performed under fluoroscopic guidance in multiple projections. Points with evoked reactions were tagged on a 3-dimentional PA model in each case. In order to confirm reproducibility of reactions, HFS was performed at least twice at each point with a response. PA models obtained from all animals were combined in one for the final analysis. RFA using an open-irrigated catheter (40 Watts; 40 s; irrigation 30 ml/min) were performed at sites with evoked reactions. Repeated HFS was performed at ablation sites. After the procedure all animals were euthanized and underwent an autopsy study. Results Low-frequency stimulation (LFS) allowed to define areas of ventricular capture (VC) where HFS was avoided due to ventricular fibrillation induction risk. During HFS the following evoked responses were documented: sinus bradycardia, sinus rhythm (SR) acceleration, phrenic nerve capture (PNC), and laryngeal recurrent nerve capture. HFS captured left and right phrenic nerves in all animals at PA trunk, and its course was tagged (Figure 1). Laryngeal recurrent nerve capture was found in 4 (23%) of animals. Atrial capture was found in all cases while LFS at the anterior aspects of both PAs even at low output, and this precluded evaluation of neural autonomic reactions in these areas. Evoked bradycardia and SR acceleration were both found during HFS in 10 (59%) of cases each. Following RFA application evoked reactions were non-reproducible in all cases. RFA was applied in areas where no PNC or VC points were observed. An autopsy study confirmed the presence of RF-induced lesions of the PA wall. Conclusions There are two important findings of our study. First, stimulation-guided PA mapping is feasible and reveals several specific responses to HFS. Ablation at points with responses leads to non-reproducibility of the evoked reactions, confirming that transcatheter RFA may be an adequate approach for PA denervation. Second, previously proposed circular PA ablation might be associated with phrenic and laryngeal recurrent nerve damage. Stimulation-guided PA denervation can be proposed as a safer procedure, and should be evaluated in clinical settings. Figure 1. PA schematic representation Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Russian Foundation for Basic Research

P1250 Thymoma invading the right atrium - multimodality imaging and its importance for managing and therapeutics

Abstract Introduction Thymoma is the most common primary neoplasm of the anterior mediastinum. Most invasive thymomas are limited to the pericardium. Only few cases of transcaval extension with intracardiac involvement have been reported. Case report We present the case of a 15-year-old boy with previous history of infectious cerebelitis without neurologic sequelae. He presented with interscapular pain for 6 weeks (not improving with symptomatic therapy) and fever for 3 days. On admission, chest radiograph exhibited an opacification in the right hilum (Figure A). He was discharged with antibiotic prescription for presumptive pneumonia. Due to persistence of complaints he was revaluated after 5 days. Signs of superior vena cava (SVC) syndrome were noted. A computerized tomography showed a large soft tissue mass of the anterior mediastinum, in right antero-lateral topography, measuring 12.5x10x9.5 cm with central calcification and extension to the right lung (Figure B). Transthoracic and transoesophageal echocardiography showed an anterior mass compressing the pulmonary artery branch (PA) and SVC with marginal invasion of the right atrium (RA) (Figure C and D). Cardiac MRI confirmed a large mass of the anterior mediastinum with extension and invasion of the right superior lobe, invasion of the superior vena cava with extension into the RA (Figure E). Transthoracic core-needle biopsy was performed and histopathological diagnosis confirmed an invasive thymoma. The case was discussed at joint cardiothoracic surgery and oncology multidisciplinary meeting and it was agreed to neoadjuvant chemotherapy regimen followed by surgery. Intraoperatively, a large tumor invading the SVC and proximal RA was found, in accordance with the echocardiographic and MRI findings. Due to unforeseen metastatic implants on the adventitia of the main PA and ascending aorta, resection of the tumor was not performed. Palliative decompression of the venous system was performed with interposition of a ringed vascular prosthesis between the left brachiocephalic vein and the right atrial appendage. (Figure F). The patient received postoperative radiotherapy and is asymptomatic without signs of SVC syndrome for 3 months. Discussion and conclusion This report illustrates a rare case of an invasive thymoma with extension to cardiac structures. Multimodality imaging for quality decision-making was imperative in the management and for surgical planning of this case. Transthoracic and transoesophageal echocardiography remain the exams of choice for the diagnosis of intracardiac disease. As demonstrated, a high index of suspicion is needed because clinical symptoms are unspecific and late diagnosis of potentially resectable tumors are associated with a poor prognosis. Abstract P1250 Figure. Multimodality imaging

Permanent atrial fibrillation and pulmonary embolism in elderly patients without deep vein thrombosis: is there a relationship?

Permanent Atrial Fibrillation (pAF) is associated with increased risk of embolic complications. The relationship between pAF and pulmonary embolism (PE) has not been extensively investigated in elderly patients. Here, we aim at verifying whether pAF is associated to an increased risk of PE in a cohort of elderly patients with and without Deep Vein Thrombosis (DVT). 235 patients older than 65years with PE with or without pAF were retrospectively enrolled and stratified by the absence or presence of DVT. The diagnosis of PE was performed by computed tomography angiography (CTA). Right echocardiographic parameters were monitored. The severity of PE was evaluated by CTA quantization (PE score = 1, involvement of main branches of pulmonary artery) and by dimer-D (> 3000µg/L). DVT was identified only in 51 cases of PE (21.7%). pAF prevalence was higher in PE without than in those with DVT (64.9% vs. 35.1%, p < 0.01). PE severity was more evident in pAF patients without than in those with DVT. Multivariate analysis of the role of pAF on PE severity confirms these results (RR = 3.41 for PE score = 1, and 8.55 for dimer-D > 3000µg/L). We conclude that in elderly patients with PE, the prevalence of pFA was doubled, in the absence of DVT, and it is associated with a more severe PE in the absence than in the presence of DVT. Thus, in the absence of DVT, pFA should be considered as cause of PE.

Kaempferol-induces vasorelaxation via endothelium-independent pathways in rat isolated pulmonary artery.

Kaempferol, a flavonoid, is the essential part of human diet. Flavonoids have different pharmacological activities like cardioprotective, anti-inflammatory and anti-oxidant. The aim of current study was to investigate vasorelaxant potential of kaempferol on rat isolated pulmonary artery and to assess the underling mechanisms. Tension experiments were conducted on both the branches of main pulmonary artery of rats. Experiments were done using isolated organ bath system by recording tension with the help of data acquisition system, Power Lab. Kaempferol (10-8-10-4.5M) caused concentration-dependent relaxation (Emax 124.33±4.37%; pD2 5.03±0.084) of endothelium-intact pulmonary artery. In endothelium-denuded arterial rings, relaxation produced by kaempferol was not different from intact artery. L-NAME, indomethacin, combination of L-NAME and indomethacin did not show any effect on kaempferol-induced relaxation. Kaempferol-induced relaxation was reduced (Emax 55.53±7.72%) in 60mMK+ pre-contracted pulmonary arterial rings. Iberiotoxin significantly decreased (Emax 71.68±11.84%) the relaxation response. However, glibenclamide, BaCl2, 4-AP (1mM) and ICI182780 did not reduce the kaempferol-induced relaxation. TEA (10mM) and 4-AP (5mM) significantly reduced relaxation. Kaempferol-induced relaxation was significantly attenuated (Emax 94.92±19.60%) in presence of ODQ. H89 significantly decreased (Emax, 98.38±8.55%) the kaempferol-induced relaxation in rat pulmonary arterial rings. HC067047 and apamin did not show any effect on kaempferol-induced relaxation. In endothelium-denuded K+ (80mM)-depolarized arterial rings, kaempferol (10μM) markedly reduced CaCl2-induced contractions (Emax 35.14±6.53% vs. control 69.04±15.19%). Kaempferol relaxes rat pulmonary artery in endothelium-independent manner through involvement of BKCa channel, sGC, PKA pathways and inhibition of Ca2+-influx through L-type calcium channels.

Assessment of the prevalence of pulmonary embolism in patients with severe pulmonary tuberculosis

Background Tuberculosis (TB) is an infectious disease of public health concern. Many reports pointed to the association between TB and thromboembolic diseases. The aim of the present study is to assess the prevalence of pulmonary embolism in patients with severe pulmonary TB. Patients and methods The study was done on 50 (35 males and 15 females) patients with severe pulmonary TB, and all patients were proved to have pulmonary TB by sputum or BAL examination and culture. In all patients, causes of hypercoagulability state were excluded, and computed tomography (CT) pulmonary angiography was done to search for evidence of pulmonary embolism. Results Eight of 50 (16%) patients had evidence of pulmonary embolism, six (12%) patients had pulmonary embolism on the segmental and subsegmental level, and two (4%) patients had pulmonary embolism in the main pulmonary artery branches. The diagnosis of pulmonary embolism was done only by CT pulmonary angiography, as clinical and chest radiography signs were masked by those for pulmonary TB. Patients with evidence of pulmonary embolism were more hypoxic and had higher levels of D-dimer, but the difference was not statistically significant. Conclusion Pulmonary embolism should be searched for in patients with severe pulmonary TB. CT pulmonary angiography is the standard method for diagnosis and can be performed in those patients who are more hypoxemic. Prophylactic anticoagulation management can be justified in these patients. Larger studies are needed to define the risk factors in patients with severe pulmonary TB who are at an increased risk of developing pulmonary embolism.

Clinical significance of peculiarities of the lesions of the vascular bed associated&#x0D; with pulmonary thromboembolism

Aim. To study effect of the level of vascular obstruction on the clinical manifestations of pulmonary embolism (PE). Material and methods. 63 patients with PE were included in this study. PE was verified by multidetector computed tomography (MSCT) with pulmonary angiography. 43 patients with high-risk PE survived the first week of the disease. In the remaining 20 patients with community-acquired pneumonia PE was diagnosed using MSCT pulmonary angiography in the first week of illness. Results. Obstruction of the trunk of the pulmonary artery or its lobar branches was detected in 34 (79.1%) patients with a high risk of PE and in only 2 (10%) ones with low-risk PE (p &lt;0,001). The development of pneumonia complicated the course of the disease in 14 (32.6%) patients with a high risk of pulmonary embolism. The clots in the segmental branches of the pulmonary artery were identified in 9 (64.3%) patients with pneumonia. In high-risk patients with PE without pneumonia the lesion of segmental branches was detected only in 1 (3.4%) case (p &lt;0,001). In patients with pneumonia at low risk of PE, the obstruction segmental branches was detected in 17 (85%) cases. Conclusion. The development of obstructive shock in PE is associated with a trunk embolism and/or the main pulmonary artery branches embolism. Infarction pneumonia is associated with the lesions of segmental branches of the pulmonary artery.

Modified Hybrid Procedure in Hypoplastic Left Heart Syndrome: Initial Experience of a Center in Northeastern Brazil.

IntroductionAlthough it only corresponds to 2.5% of congenital heart defects, hypoplastic left heart syndrome (HLHS) is responsible for more than 25% of cardiac deaths in the first week of life. Palliative surgery performed after the second week of life is considered an important risk factor in the treatment of HLHS.ObjectiveThe aim of this study is to describe the initial experience of a medical center in Northeastern Brazil with a modified off-pump hybrid approach for palliation of HLHS.MethodsFrom November 2012 through November 2015, the medical records of 8 patients with HLHS undergoing hybrid procedure were retrospectively evaluated in a tertiary private hospital in Northeastern Brazil. The modified off-pump hybrid palliation consisted of stenting of the ductus arteriosus guided by fluoroscopy without contrast and banding of the main pulmonary artery branches. Demographic and clinical variables were recorded for descriptive analysis.ResultsEight patients were included in this study, of whom 37.5% were female. The median age and weight at the time of the procedure was 2 days (p25% and p75% = 2 and 4.5 days, respectively) and 3150 g (p25% and p75% = 3077.5 g and 3400 g, respectively), respectively. The median length in intensive care unit stay was 6 days (p25% and p75% = 3.5% and 8 days, respectively). There were no in-hospital deaths. Four patients have undergone to the second stage of the surgical treatment of HLHS.ConclusionIn this series, the initial experience with the modified off-pump hybrid procedure showed to be safe, allowing a low early mortality rate among children presenting HLHS.

Elevated gamma glutamyl transferase levels are associated with the location of acute pulmonary embolism. Cross-sectional evaluation in hospital setting.

The location of embolism is associated with clinical findings and disease severity in cases of acute pulmonary embolism. The level of gamma-glutamyl transferase increases under oxidative stress-related conditions. In this study, we investigated whether gamma-glutamyl transferase levels could predict the location of pulmonary embolism. Hospital-based cross-sectional study at Cumhuriyet University, Sivas, Turkey. 120 patients who were diagnosed with acute pulmonary embolism through computed tomography-assisted pulmonary angiography were evaluated. They were divided into two main groups (proximally and distally located), and subsequently into subgroups according to thrombus localization as follows: first group (thrombus in main pulmonary artery; n = 9); second group (thrombus in main pulmonary artery branches; n = 71); third group (thrombus in pulmonary artery segmental branches; n = 34); and fourth group (thrombus in pulmonary artery subsegmental branches; n = 8). Gamma-glutamyl transferase levels on admission, heart rate, oxygen saturation, right ventricular dilatation/hypokinesia, pulmonary artery systolic pressure and cardiopulmonary resuscitation requirement showed prognostic significance in univariate analysis. The multivariate logistic regression model showed that gamma-glutamyl transferase level on admission (odds ratio, OR = 1.044; 95% confidence interval, CI: 1.011-1.079; P = 0.009) and pulmonary artery systolic pressure (OR = 1.063; 95% CI: 1.005-1.124; P = 0.033) remained independently associated with proximally localized thrombus in pulmonary artery. The findings revealed a significant association between increased existing embolism load in the pulmonary artery and increased serum gamma-glutamyl transferase levels.

Diagnosis of Ductal Aneurysm Using Three-Dimensional CT Reconstruction

The prevalence of ductal aneurysms is approximately 8.8% [2]. Ductal aneurysms are associated with serious complications, which makes accurate diagnosis prudent. Diagnosis is traditionally made by echocardiography, however, additional imaging modalities are sometimes required for a definitive diagnosis. Our patient, D.C., is a full-term newborn male who was transferred from an outside hospital to our Neonatal Intensive Care Unit secondary to respiratory failure and dysmorphism. His physical examination was significant for hypertelorism and low-set ears. He had increased precordial activity and a 3/6 holosystolic murmur heard throughout the precordium. An echocardiogram was performed on day of life 5, which showed a primum atrial septal defect (ASD) with left-to-right shunt, a secundum ASD with left-to-right shunt, and atrioventricular canaltype ventricular septal defect with no physiologic shunt secondary to atrioventricular valve tissue filling the defect. At that time echocardiography demonstrated significant left pulmonary artery stenosis. A follow-up echocardiogram was performed to further evaluate the caliber of the left pulmonary artery. A 1.6 9 1.8-cm cystic mass was noted anterior to and to the left of the main pulmonary artery/left pulmonary artery junction. There appeared to be a connection via a small communication to the main pulmonary artery (Fig. 1). A CT angiogram was performed, which showed a well-circumscribed contrast-filled structure measuring 1.7 9 1.4 9 1.2 cm arising from the anterior aspect of the proximal portion of the descending thoracic aorta, located anterolateral to the left main pulmonary artery branch, most consistent with a pseudoaneurysm. However, the exact anatomy was still difficult to precisely delineate. Therefore, we used three-dimensional reconstruction of the CT angiogram to show the aneurysm in connection with the ductus arteriosus and to demonstrate compression of the left pulmonary artery by the aneurysm (Fig. 2). Ductal aneurysms are rare and are more frequently associated with patients who have had surgical ligation of the ductus arteriosus or in association with connective tissue disorders [1]. One study demonstrated a prevalence of 8.8% in all newborn infants [2]. Ductal aneurysms usually are asymptomatic and incidentally discovered on routine echocardiographic evaluation or diagnosed by fetal echocardiogram. Although rare, ductal aneurysms are associated with serious complications, which include thromboembolism, infection, rupture, and death [3]. The conventional method to identify ductal aneurysm anatomy is by two-dimensional echocardiogram with color Doppler. However, some patients require additional imaging with CT angiography or MRI to further define the anatomy [1]. In our patient, the connection between the aneurysm and the artery was difficult to isolate on two-dimensional echocardiogram and CT angiogram. Therefore, three-dimensional reconstruction of the CT angiogram was necessary to make the exact diagnosis. Additionally, the three-dimensional reconstruction replicated the exact area of aneurysmal connection to the pulmonary artery. Three-dimensional CT has been described more often in the adult literature for diagnosis of aneurysms. The most common use is as a diagnostic tool for circle of Willis aneurysms. However, three-dimensional CT angiography has been used to diagnose aortic aneurysms in the adult population. In pediatrics, three-dimensional CT angiography Deneen Heath and Russell Cross contributed equally to this work.

Expression of 15-lipoxygenases in pulmonary arteries after hypoxia

We have previously reported that subacute hypoxia upregulates and activates the steady state expression of pulmonary artery 15-lipoxygenase (15-LOX). However, there are two 15-LOX isoenzymes, 15-LOX-1 and 15-LOX-2, which are expressed in pulmonary arteries that have not been previously studied. In the present study, we identified the differential expression of the two isoenzymes in normoxic or hypoxic intrapulmonary arteries of rats, pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs) from the main branches of pulmonary artery of neonatal bovines. Immunohistochemistry, in situ hybridisation, RT-PCR, and Western blotting were employed to identify the differential expression of the two isoenzymes. 15-LOX-1 was expressed in both normoxic and hypoxic rat arteries. In contrast, 15-LOX-2 was hardly detectable in normoxic vessels by immunohistochemistry and Western blotting, but it was detected in hypoxic arteries. In cultured bovine pulmonary artery cells, 15-LOX-1 and 15-LOX-2 were found to be different in cellular distribution. The expression of 15-LOX-1 was stronger in PAECs than in PASMCs, whereas, 15-LOX-2 was weaker in PAECs than in PASMCs. Moreover, the expressions of both 15-LOX isoenzymes increased dramatically after hypoxia. These results suggest that both isoenzymes of 15-LOXs are upregulated after hypoxia.

Response

We welcome Laffon et al's interest and reply to their concerns about the validity of comparing their pulmonary artery (PA) pulse wave velocity (PWV) data (1) with our own (2). Given the scarcity of literature on the subject, we considered it reasonable to discuss their work [particularly as it employed cardiovascular magnetic resonance (CMR)]. Indeed, we have identified just two other non-invasive studies (3, 4) that used the transit-time approach, like ours. Only one, which employed fluorocardiography, had comparable results [conus to right hilum, 2 m/sec (3) vs. 2.33 m/sec for right PA and 2.09 m/sec for left PA (2)]. The transit-time method records the time a pulse takes to cover a known distance and provides a “weighted” measure of PWV over this path length. By using a high-temporal resolution acquisition to analyze flow arrival, ours was the first study to prove this to be achievable in the PAs with CMR. Conversely, Laffon et al approached PWV “locally” by estimating the elastic modulus using the equation proposed by Frank, and Bramwell and Hill (5). “Local” PWV has also been estimated by CMR in work reported after ours was submitted where the change in flow was related to the change in diameter in the early systolic phases of an MPA velocity map (6). In the 8 healthy volunteers included in the study, a mean PWV of 1.84 m/sec was found. It is our assertion that as long as the differences between the methods (as well as their limitations) are acknowledged clearly, discussion of all available measurements in this scarcely reported field will remain warranted [see the chapter on wave propagation in Milnor's Hemodynamics (5)]. Laffon et al's main concern centers on the inclusion of the main PA's branch point in the examined region and the effects this might have on transit-time PWV. Because of the limitations imposed by pulmonary anatomy and temporal resolution, this was the only way to make the delay in pulse wave arrival discernible. Although future improvements in velocity mapping could limit study to a single vessel only, it will not stop reflections originating outside the examined region “contaminating” the area of interest. Although it was not the intention of this work to examine the issue of reflections or make comment on the behavior of the pulse wave at any specific position during its transit, we considered this problem when choosing our “marker” of pulse wave arrival. In normal subjects, where one could speculate that the backward wave would be both small and slow moving, we believed a point halfway up the wavefront would likely be relatively unaffected during its transmission and therefore robust. However, in pulmonary hypertension, where the wave profile changes to a far greater degree during propagation, the same point would likely be unrecognizable by the end of the path length. So, just as Fleischner et al (3) and Ring and Kurbatov (4) did over 50 years ago, we will be focusing on the wavefront foot, which we anticipate will prove least contaminated and hence easiest to study. In conclusion, we believe that the transit-time measure is a valid one, both in health and disease, as long as the effect of anticipated reflections is minimized. William M. Bradlow BM, BS*, Peter D. Gatehouse PhD , Ray L. Hughes MSc , Aoife B. O'Brien PhD , J. Simon R. Gibbs MD?, David N. Firmin PhD?, Raad H. Mohiaddin MD?, * Imperial College, London, CMR Unit, Royal Brompton Hospital, London, UK, CMR Unit, Royal Brompton Hospital, London, UK, Department of Medical Physics and Bioengineering, University College Hospital, Galway, Ireland, ? Imperial College, London, National Pulmonary Hypertension Service, Hammersmith Hospital, London, UK, ? Imperial College, London, CMR Unit, Royal Brompton Hospital, London, UK

Antenatal prediction of pulmonary hypoplasia by acceleration time/ejection time ratio of fetal pulmonary arteries by Doppler blood flow velocimetry

Objective: The purpose of this study was to develop a new method for the antenatal prediction of pulmonary hypoplasia by Doppler blood flow velocimetry. Study Design: One hundred seventy-seven fetuses (160 normal fetuses and 17 fetuses with congenital anomalies that may affect fetal lung growth and/or development) were studied. Blood flow waveforms at the main branches of the pulmonary arteries were recorded by Doppler echocardiography from 20 to 39 weeks of gestation. The ratio of acceleration time to ejection time was calculated from the waveform as a parameter to predict pulmonary hypoplasia. Results: Doppler waveform of normal fetal pulmonary artery showed a “spike-and-dome” pattern. The normal values of acceleration time/ejection time ratio from the right and left pulmonary arteries were 0.17 ± 0.04 and 0.15 ± 0.04, respectively. These values were not significantly altered through the gestational age observed in this study. The acceleration time/ejection time ratio of either right or left pulmonary artery was measured successfully in all cases of fetal congenital anomalies. In 8 of 17 fetuses, acceleration time/ejection time ratio was measured at both of the pulmonary arteries. Because of a congenital anomaly that affected the fetal lung or thorax asymmetrically (as in congenital diaphragmatic hernia or congenital cystic adenomatoid malformations of the lung), the acceleration time/ejection time ratio of both of the pulmonary arteries could be measured in only 5 of 13 fetuses. The technical difficulties for the measurement always existed in the affected side. Eleven of the 17 fetuses with congenital anomalies survived without signs of clinical pulmonary hypoplasia or persistent pulmonary hypertension of the newborn infant. The fetuses revealed normal acceleration time/ejection time ratio from at least one pulmonary artery. The remaining 6 fetuses died of pulmonary hypoplasia, and the diagnosis was confirmed by autopsy or clinical findings. Of those 6 fetuses, 5 fetuses demonstrated the acceleration time/ejection time ratio below normal in one side, and the ratio could not be obtained on the other side; 1 fetus showed the acceleration time/ejection time ratio below the normal range in both sides. Conclusion: The acceleration time/ejection time ratio by Doppler velocimetry that was obtained at the main branches of fetal pulmonary artery was consistent throughout gestational age from 20 to 39 weeks. This ratio appears to be an accurate parameter with which to predict the subsequent development of pulmonary hypoplasia and clinical outcomes of the newborn infants with high positive and negative predictive values (positive predictive value, 100%; negative predictive value, 100%). Am J Obstet Gynecol 2003;188:228-33.

Exposure to chronic hypoxia induces qualitative changes of collagen in the walls of peripheral pulmonary arteries

Qualitative changes of vascular wall matrix collagens in chronic hypoxic pulmonary hypertension were studied by gel electrophoresis. Male adult rats (n = 12) were exposed to hypoxia (F i02 = 0.1, 3 wks). Control rats (n = 13) were kept in air. Samples of peripheral pulmonary arteries (PPA, diam. 100 – 400 μm), main branches of pulmonary artery, and aorta were dissected. Arterial samples were treated with 4M guanidine-HCl to remove noncollagenous moieties and the collagenous stroma was dissolved by limited pepsin digestion at low pH. Low molecular mass peptides (M. W. approx. 76 and 66 kD) were detected in the gel electrophoretic profile of collagen peptides of PPA of the chronically hypoxic animals and in aorta of both hypoxic and normoxic groups. These peptides were absent in the PPA of normoxic rats. Since the 76 kD peptide bound anticollagen type I antibodies, it appears to be of collagenous nature and it may be the result of collagenolytic activity in PPA isolated from hypoxic lungs. This was confirmed by zymography. We conclude that exposure of rats to chronic hypoxia results in the presence of low molecular mass peptides in the wall matrix of PPA which resemble those found in aorta of normoxic animals. Collagenolytic activity in the walls of peripheral pulmonary arteries may participate in the mechanism of lung vascular remodelling in chronic hypoxia.

Development of neo-coarctation in patients with transposed great arteries and hypoplastic aortic arch after Lecompte modification of anatomical correction

We report on three patients with kinking in the proximal aortic arch that developed after Lecompte modification of the arterial switch operation. Two patients had a previous subclavian patch repair of coarctation of the aorta and had an associated hypoplasia of the transverse aortic arch, and one patient had hemodynamically mild coarctation at the anatomical repair. A severe pressure gradient across the kinked area ("neo-coarctation") necessitating reoperation developed in one patient. The acute arch angulation appears to be due to an excessive posterior displacement of the ascending aorta by the anterior relocation of either the right or left main pulmonary artery branch from underneath the aortic arch. A foreshortened and frequently hypoplastic transverse aortic arch, a common association with coarctation of the aorta, appears to be especially vulnerable to the development of "neo-coarctation" after the Lecompte modification of the anatomical repair of transposed great arteries.