Low Pulmonary Blood Flow Research Articles

Abstract 15081: The Viscoelastic Yield Stress of Blood is Negatively Associated With Pulmonary Blood Flow in the Fontan Circulation

Introduction: In the Fontan (FN) circulation pulmonary blood flow (Qp) is passive, resulting in severely decreased shear rate and velocity in pulmonary arteries to the point of stasis. Yield stress (YS) is the shear stress required for blood to transition from stasis to a moving fluid. Therefore, YS may be a determinant of Qp in FN. We evaluated YS in patients with FN and Glenn (GLN) circulations and whether increased YS is associated with decreased Qp. Methods: We enrolled 20 patients with biventricular (2V) congenital heart disease (CHD) and 41 patients with single ventricle CHD (19 FN and 22 GLN) who were undergoing a clinically indicated cardiac catheterization. Two patients were excluded due to pulmonary vascular disease. We obtained blood samples at the time of catheterization and measured blood viscosity across shear rates 1 s -1 to 1000 s -1 using a Rheolog viscometer We calculated YS by curve-fitting of the viscosity measurements to a Casson fluid model. Hypothesis: We hypothesize that higher yield stress will be associated with lower pulmonary blood flow in Fontan circulation. Results: The FN group was the oldest and had the largest BSA (FN>2V>GLN; p<0.0001). Hematocrit was highest in GLN (GLN>FN>2V; p<). Blood viscosity was higher across all shear rates in GLN compared to both FN and 2V (p<0.001 for all shear rates) and higher in FN than 2V from 1 s -1 to 150 s -1 (p<0.05 for all shear rates). YS was highest in GLN (GLN>FN>2V; p< ). YS was negatively associated with Qp in both FN (R2 0.33, p=0.02) and GLN (R2 0.2, p=0.038), but not 2V (see Figure). Hematocrit was negatively associated with Qp in 2V (R2 0.34, p=0.028) and trended toward negative association in FN (R2 0.27, p=0.099), but not in GLN. Stepwise regression of Hct and YS vs Qp in FN demonstrated YS as the primary predictor of Qp. Conclusions: Our data demonstrate that the yield stress of blood derived from the Casson fluid model is a significant determinant of pulmonary blood flow in FN circulation.

Differential Alveolar and Systemic Oxygenation during Preterm Resuscitation with 100% Oxygen during Delayed Cord Clamping.

Delayed cord clamping (DCC) and 21 to 30% O2 resuscitation is recommended for preterm infants but is commonly associated with low pulmonary blood flow (Qp) and hypoxia. 100% O2 supplementation during DCC for 60 seconds followed by 30% O2 may increase Qp and oxygen saturation (SpO2). Preterm lambs (125-127 days of gestation) were resuscitated with 100% O2 with immediate cord clamping (ICC, n = 7) or ICC + 30% O2, and titrated to target SpO2 (n = 7) or DCC + 100% O2 for 60 seconds, which followed by cord clamping and 30% O2 titration (n = 7). Seven preterm (23-27 weeks of gestation) human infants received continuous positive airway pressure (CPAP) + 100% O2 for 60 seconds during DCC, cord clamping, and 30% O2 supplementation after cord clamping. Preterm lambs in the ICC + 100% O2 group resulted in PaO2 (77 ± 25 mm Hg), SpO2 (77 ± 11%), and Qp (27 ± 9 mL/kg/min) at 60 seconds. ICC + 30% O2 led to low Qp (14 ± 3 mL/kg/min), low SpO2 (43 ± 26%), and PaO2 (19 ± 7 mm Hg). DCC + 100% O2 led to similar Qp (28 ± 6 mL/kg/min) as ICC + 100% O2 with lower PaO2. In human infants, DCC + CPAP with 100% O2 for 60 seconds, which followed by weaning to 30% resulted in SpO2 of 92 ± 11% with all infants >80% at 5 minutes with 100% survival without severe intraventricular hemorrhage. DCC + 100% O2 for 60 seconds increased Qp probably due to transient alveolar hyperoxia with systemic normoxia due to "dilution" by umbilical venous return. Larger translational and clinical studies are warranted to confirm these findings. · Transient alveolar hyperoxia during delayed cord clamping can enhance pulmonary vasodilation.. · Placental transfusion buffers systemic oxygen tension and limits hyperoxia.. · Use of 100% oxygen for 60 seconds during DCC was associated with SpO2 ≥80% by 5 minutes..

Cardiovascular fetal-to-neonatal transition: an in silico model.

Previous models describing the fetal-to-neonatal transition often lack oxygen saturation levels, homeostatic control mechanisms, phasic hemodynamic signals, or describe the heart with a time-varying elastance model. We incorporated these elements in the adapted CircAdapt model with the one-fiber model for myocardial contraction, to simulate the hemodynamics of the healthy term human fetal circulation and its transition during the first 24 h after birth. The fetal-to-neonatal model was controlled by a time- and event-based script of changes occurring at birth, such as lung aeration and umbilical cord clamping. Model parameters were based on and validated with human and animal data. The fetal circulation showed low pulmonary blood flow, right ventricular dominance, and inverted mitral and tricuspid flow velocity patterns, as well as high mean ductus venosus flow velocity. The neonatal circulation showed oxygen saturation levels to gradually increase to 98% in the first 15 min after birth as well as temporary left ventricular volume overload. Hemodynamics of the term fetus and 24-h-old neonate, as well as the events occurring directly after birth and the transition during the first 24 h after birth, were realistically represented, allowing the model to be used for educational purposes and future research. With the addition of oxygen saturation levels, homeostatic pressure-flow control mechanisms, and the one-fiber model for myocardial contraction, a new closed-loop cardiovascular model was constructed to give more insight into the healthy term human fetal circulation and its cardiovascular transition during the first 24 h after birth. Extensive validation confirmed that the hemodynamics of the term fetus and the fetal-to-neonatal transition were realistically represented with the model. This well-validated and versatile model can serve as an education as well as a research platform for in silico investigation of fetal-to-neonatal hemodynamic changes under a wide range of physiological and pathophysiological conditions.

Insights From Invasive Cardiopulmonary Exercise Testing of Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) affects tens of millions worldwide; the causes of exertional intolerance are poorly understood. The ME/CFS label overlaps with postural orthostatic tachycardia (POTS) and fibromyalgia, and objective evidence of small fiber neuropathy (SFN) is reported in approximately 50%of POTS and fibromyalgia patients. Can invasive cardiopulmonary exercise testing (iCPET) and PGP9.5-immunolabeled lower-leg skin biopsies inform the pathophysiology of ME/CFS exertional intolerance and potential relationships with SFN? We analyzed 1,516 upright invasive iCPETs performed to investigate exertional intolerance. After excluding patients with intrinsic heart or lung disease and selecting those with right atrial pressures (RAP)<6.5mmHg, results from 160 patients meeting ME/CFS criteria who had skin biopsy test results were compared with 36 control subjects. Rest-to-peak changes in cardiac output (Qc) were compared with oxygen uptake (Qc/VO2 slope) to identify participants with low, normal, or high pulmonary blood flow by Qc/VO2 tertiles. During exercise, the 160 ME/CFS patients averaged lower RAP (1.9 ± 2 vs8.3 ± 1.5; P< .0001) and peak VO2 (80%± 21%vs101.4%± 17%; P< .0001) than control subjects. The low-flow tertile had lower peak Qc than the normal and high-flow tertiles (88.4%± 19%vs99.5%± 23.8%vs99.9%± 19.5%predicted; P< .01). In contrast, systemic oxygen extraction was impaired in high-flow vslow- and normal-flow participants (0.74%± 0.1%vs0.88 ± 0.11 vs0.86 ± 0.1; P< .0001) in association with peripheral left-to-right shunting. Among the 160 ME/CFS patient biopsies, 31%were consistent with SFN (epidermal innervation≤5.0%of predicted; P< .0001). Denervation severity did not correlate with exertional measures. These results identify two types of peripheral neurovascular dysregulation that are biologically plausible contributors to ME/CFS exertional intolerance-depressed Qc from impaired venous return, and impaired peripheral oxygen extraction. In patients with small-fiber pathology, neuropathic dysregulation causing microvascular dilation may limit exertion by shunting oxygenated blood from capillary beds and reducing cardiac return.

Serum biomarker analysis at the protein level on pulmonary hypertension secondary to old anterior myocardial infarction.

Pulmonary hypertension (PH) related to old anterior myocardial infarction (OAMI) always accompanies a bad prognosis, and thus, we aimed to screen serum biomarkers related to PH in OAMI patients. According to right ventricular systolic pressure, we divided mice into sham, OAMI, and PH-OAMI groups and evaluated body, heart and lung weight, heart function, pulmonary blood flow velocity, cardiac fibrotic area, and pulmonary arteriole condition. Lung and serum were under the proteomic analysis. Levels of three identified proteins were measured. Compared with sham and OAMI mice, PH-OAMI mice showed heart dysfunction, low pulmonary blood flow, high right ventricular systolic pressure, heavy heart and lung weight, large cardiac fibrotic area, and pathological pulmonary arteriole remodeling (P<0.05 or P<0.01). Haptoglobin, annexin A5, and Ig mu chain C region of lung and serum were changed significantly in PH-OAMI mice (P<0.01). Then, we collected serum and clinical data, measured three serum protein levels, and performed multivariate regression and receiver operating characteristic curve in patients (normal, OAMI, and PH-OAMI groups). Compared with normal and OAMI patients, serum levels of three proteins in PH-OAMI patients were also altered notably (P<0.01). These three proteins can predict PH in OAMI patients (P<0.01). Receiver operating characteristic curve analysis revealed haptoglobin (cut-off value: 78.295, sensitivity: 62.8%, specificity: 94.4%), annexin A5 (cut-off value: 151.925, sensitivity: 41.9%, specificity: 82.4%), and Ig mu chain C region (cut-off value: 168.885, sensitivity: 86.0%, specificity: 79.6%) (P<0.01). Three circulating serum proteins can be useful for the categorization of OAMI patients with and without PH.

Bidirectional Ductal Shunting and Preductal to Postductal Oxygenation Gradient in Persistent Pulmonary Hypertension of the Newborn.

Background: The aim was to evaluate the relationship between the direction of the patent ductus arteriosus (PDA) shunt and the pre- and postductal gradient for arterial blood gas (ABG) parameters in a lamb model of meconium aspiration syndrome (MAS) with persistent pulmonary hypertension of the newborn (PPHN). Methods: PPHN was induced by intermittent umbilical cord occlusion and the aspiration of meconium through the tracheal tube. After delivery, 13 lambs were ventilated and simultaneous 129 pairs of pre- and postductal ABG were drawn (right carotid and umbilical artery, respectively) while recording the PDA and the carotid and pulmonary blood flow. Results: Meconium aspiration resulted in hypoxemia. The bidirectional ductal shunt had a lower postductal partial arterial oxygen tension ([PaO2] with lower PaO2/FiO2 ratio—97 ± 36 vs. 130 ± 65 mmHg) and left pulmonary flow (81 ± 52 vs. 133 ± 82 mL/kg/min). However, 56% of the samples with a bidirectional shunt had a pre- and postductal saturation gradient of < 3%. Conclusions: The presence of a bidirectional ductal shunt is associated with hypoxemia and low pulmonary blood flow. The absence of a pre- and postductal saturation difference is frequently observed with bidirectional right-to-left shunting through the PDA, and does not exclude a diagnosis of PPHN in this model.

The Spectrum of Cardiac Anomalies Associated with Heterotaxy: A Single-Center Study of a Large Series Based on Computed Tomography.

The aim of the study was to identify and correlate the anatomical variants of cardiac structures among patients with heterotaxy. In this retrospective cross-sectional analysis of 13years duration, 302 patients of congenital heart diseases associated with heterotaxy were studied. All these patients had undergone a meticulous clinical evaluation, echocardiography, and cardiac computed tomography. The mean age of the cohort was 38.4months, with 180 males and 122 females. The cohort had 184 patients of right isomerism and 118 of left isomerism. More than half of the cohort had abnormal pulmonary veins. Over 75% of the cohort had low pulmonary blood flow. Abnormal relationship of great arteries was seen in nearly 69% of the cohort. Atrio-venticular canal defect was the commonest anatomical variant. Overall, 43% of the cohort had single ventricle physiology, predominantly associated with right isomerism. Heterotaxy forms a difficult anatomical subset to comprehend due to the plethora of possible abnormalities. However, unless the cardiac and visceral anatomy is delineated well, the surgical plan becomes suboptimal and often elusive, leaving tough choices for cardiac surgeon. It is essential to obtain all the possible anatomical information using additional imaging modalities to devise a basis for a comprehensive plan for medical and surgical management. A better understanding of the genetic and molecular factors in the etiology, coupled with the application of state-of-the-art imaging techniques, is likely to add to our knowledge of heterotaxy to bring about improved surgical outcomes and a better quality of life for patients suffering from this complex entity.

Reliability of ultrasound in confirming endotracheal tube placement as a new and fast tool

BackgroundChest ultrasound has been an important tool for the diagnosis of many chest diseases, and, recently, it became an important tool for confirmation of the site of endotracheal tube placement. In our study, we used the ultrasound for this confirmation and compared this with capnography and clinical examination as gold standards and also with chest radiograph.Patients and methodsThis is a cross-sectional study conducted in our chest ICU from January 2019 to August 2019. We included 30 chronic obstructive pulmonary disease patients with acute respiratory failure who needed endotracheal intubation according to the protocols. Ultrasound was used to identify and confirm endotracheal tube placement simultaneously with a quantitative waveform capnography (end-tidal carbon dioxide), clinical methods, and chest radiograph. Confirmation of tube placement and time taken for the confirmation were noted by our staff.ResultsOf the 30 intubation attempts, six (20%) had esophageal intubations. The sensitivity and specificity of diagnosis using ultrasonography were 95.8 and 93.3%, respectively. This was statistically comparable with the other three modalities. The time taken to confirm tube placement with ultrasonography was 7.7±1.6 s compared with waveform capnography, clinical examination, and chest radiograph, which were18.8±2.6, 26.1±3.4, and 73.6±7.7 s, respectively. The time taken by ultrasonography was significantly less.ConclusionSonar-confirmed endotracheal intubation saves time and life, particularly in patients with low pulmonary blood flow in comparison with other traditional methods of confirmation.

Colour Doppler ultrasound after major cardiac surgery improves diagnostic accuracy of the pulmonary infection score in acute respiratory failure: A prospective observational study.

Postoperative pneumonia is a frequent complication after cardiac surgery, and its diagnosis is difficult. Little is known about the diagnostic accuracy of lung ultrasound (LUS) in the detection of pneumonia in cardiac surgical patients. The substitution of chest radiography by colour Doppler LUS (LUS-sCPIS) in the simplified clinical pulmonary infection score (sCPIS) could improve the diagnosis of pneumonia following cardiac surgery. The aim of this study was to compare the diagnostic accuracy of LUS-sCPIS and of sCPIS alone in the detection of postoperative pneumonia after cardiac surgery. A prospective study of diagnostic accuracy. A Surgical Intensive Care Unit of a French University Hospital. Fifty-one patients with acute respiratory failure within 72 h after cardiac surgery were enrolled between January and May 2015. The two index tests, LUS-sCPIS and sCPIS, were calculated for all patients at the onset of acute respiratory failure. The reference standard for the diagnosis of pneumonia was based on the consensus of three physicians, blind to the sCPIS and LUS-sCPIS data, based on a posthoc review of all the clinical, radiological and microbiological evidence. The diagnostic accuracy of LUS-sCPIS was compared with that of sCPIS in the detection of postoperative pneumonia. Pneumonia was diagnosed in 26 out of 51 patients. The LUS-sCPIS detected the presence of pneumonia with a sensitivity of 92% (95% CI 0.85 to 0.99) and a specificity of 68% (95% CI 0.55 to 0.81). The sCPIS detected the presence of pneumonia with a sensitivity of 35% (95% CI 0.22 to 0.48) and a specificity of 84% (95% CI 0.74 to 0.94). The area under the curve (AUC) of LUS-sCPIS at 0.80 (95% CI 0.69 to 0.91) was higher than the AUC of sCPIS at 0.59 (95% CI 0.47 to 0.71; P = 0.0008). Compared with sCPIS, LUS-sCPIS improved diagnostic accuracy in the detection of postoperative pneumonia in patients with acute respiratory failure after cardiac surgery. It could be a useful bedside tool to guide pneumonia management. Clinicaltrials.gov identifier: NCT03279887.

Renal dysfunction is associated with higher central venous pressures in patients with Fontan circulation.

Elevated central venous pressure (CVP) has deleterious effects on several organ systems in patients with Fontan circulation. However, the relationship between CVP and estimated glomerular filtration rate (eGFR) has not been assessed in patients with Fontan circulation. Patients with Fontan circulation whose hemodynamics were assessed by catheterization between 1987 and 2015 and had a serum creatinine measured within 72 hours prior to the procedure were included for analysis. Patients with primary kidney disease were excluded. Renal function was calculated by "bedside Schwartz" equation in children (< 18 years) and Modification of Diet in Renal Disease equation in adults. Renal dysfunction (RD) was defined by eGFR < 90mL/min/1.73m2 . Fontan patients with and without RD were compared based on demographics, co-morbidities, medication use, echocardiographic findings, hemodynamics assessed at time of catheterization, and laboratory testing values. Sixty-seven patients with Fontan circulation met inclusion criteria and 15 patients (22%) had RD; eGFR (mL/min/1.73m2 ) was 60-89in 13 (87%), 45-59in 1 (7%), and 30-45in 1 (7%). Compared to patients with eGFR equal to or greater than 90, patients with RD had higher CVP (18.0 [15.0-21.0] mm Hg vs 13.5 [12.3-16.0] mm Hg (P = 0.001), lower pulmonary blood flow 2.2 [1.9-2.6] L/min/m2 vs 2.8 [2.3-3.7] L/min/m2 , higher ventricular end-diastolic pressure 10.5 [7.0-17.3] mm Hg vs 8.0 [6.0-10.0] mm Hg (P = 0.050), were more likely to have worse atrioventricular valve regurgitation (P = 0.02) and were more likely to be African American (P = 0.009). In this study population, renal dysfunction in patients with Fontan circulation is associated with increased CVP and factors that affect CVP. African Americans with Fontan circulation may be at particular risk for renal dysfunction. Continued investigation of the effects of venous congestion on kidneys and other factors associated with renal dysfunction in patients with Fontan circulation is warranted.

Replace “Have to” With “Want to”

Replace “Have to” With “Want to”

The fascinating story of surfactant.

The fascinating story of surfactant.

A Rare Case of Successive Pregnancies in a Woman with Complex Cyanotic Congenital Heart Disease after Glenn Palliation

The bidirectional Glenn procedure is an integral step in the optimal palliation for single ventricular physiology in many forms of complex congenital heart disease. An increasing number of women who have undergone this connection in childhood are now reaching childbearing years. Low pulmonary blood flow and volume over load on the single ventricle pose several problems during pregnancy. We are reporting a 33-year-old lady with congenital tricuspid atresia and mild pulmonary stenosis who had late Bidirectional Glenn procedure with pulmonary forward flow and later underwent six successful pregnancies, with delivery of six low birth weight babies with no reported complications.

Neonatal resuscitation adhering to oxygen saturation guidelines in asphyxiated lambs with meconium aspiration.

The Neonatal Resuscitation Program (NRP) recommends upper and lower limits of preductal saturations (SpO2) extrapolated from studies in infants resuscitated in room air. These limits have not been validated in asphyxia and lung disease. Seven control term lambs delivered by cesarean section were ventilated with 21% O2. Thirty lambs with asphyxia with meconium aspiration were randomly assigned to resuscitation with 21% O2 (n = 6), 100% O2 (n = 6), or initiation with 21% O2 followed by variable FIO2 to maintain NRP target SpO2 ranges (n = 18). Hemodynamic and ventilation parameters were recorded for 15 min. Control lambs maintained preductal SpO2 near the lower limit of NRP target range. Asphyxiated lambs had low SpO2 (38 ± 2%), low arterial pH (6.99 ± 0.01), and high PaCO2 (96 ± 7 mm Hg) at birth. Resuscitation with 21% O2 resulted in SpO2 values below the target range with low pulmonary blood flow (Qp) compared to variable FIO2 group. The increase in PaO2 and Qp with variable FIO2 resuscitation was similar to control lambs. Maintaining SpO2 as recommended by NRP by actively adjusting inspired O2 leads to effective oxygenation and higher Qp in asphyxiated lambs with lung disease. Our findings support the current NRP SpO2 guidelines for O2 supplementation during resuscitation of an asphyxiated neonate.

Results of Palliation With an Initial Modified Blalock-Taussig Shunt in Neonates With Single Ventricle Anomalies Associated With Restrictive Pulmonary Blood Flow

We report our current-era results after placement of a modified Blalock-Taussig shunt (mBTS) as the first surgery in the multistage palliation strategy of neonates born with single ventricle (SV) anomalies associated with restrictive pulmonary blood flow. Between 2002 and 2012, 174 neonates with SV underwent mBTS. Competing risks analysis modeled events after mBTS (death or transplantation, transition to Glenn) and subsequently after Glenn (death or transplantation, transition to Fontan) and examined risk factors affecting outcomes. Competing risks analysis showed that 2 years after mBTS 27% of patients had died or received transplantation and 73% had undergone Glenn. Five years after Glenn, 6% had died, 73% had undergone Fontan, and 21% were alive awaiting Fontan. Overall survival 8 years after mBTS was 68%. On multivariable analysis, risk factors for mortality were increased shunt size to weight ratio (hazard ratio [HR]:1.2 per 0.1 ratio increase [1.0 to 1.4], p = 0.015), postoperative extracorporeal membrane oxygenation (HR: 4.0 [2.2 to 7.4], p < 0.001), chromosomal and extracardiac malformations (HR: 2.5 [1.3 to 5.0], p = 0.008), cardiopulmonary bypass use (HR: 2.5 [1.3 to 4.5], p = 0.004), and underlying pulmonary atresia with intact ventricular septum (PAIVS) or atrial isomerism (HR: 2.1 [1.1 to 4.2], p = 0.035). Palliation outcomes with mBTS in SV patients trail behind the generally improved results of congenital heart surgery. Several anatomic and patient-related factors continue to affect survival. Mortality is high in low weight neonates in whom a balance between overcirculation due to large shunt and low pulmonary blood flow and risk of occlusion due to small shunt is difficult to attain. Patients with chromosomal and extracardiac malformations, atrial isomerism, and PAIVS continue to be the most challenging and are associated with higher hospital and interstage mortality.

The hemodynamic basis of exercise intolerance in tricuspid regurgitation.

Patients with severe tricuspid regurgitation (TR) frequently present with exertional fatigue and dyspnea, but the hemodynamic basis for exercise limitation in people with TR remains unclear. Twelve subjects with normal left ventricular (LV) ejection fraction and grade ≥3 TR underwent high-fidelity invasive hemodynamic exercise testing with simultaneous expired gas analysis and were compared with 13 age- and sex-matched controls. At rest, TR subjects had lower pulmonary blood flow (3.6±0.4 versus 5.1±1.9 L/min; P=0.01), increased right atrial pressure (12±5 versus 4±1 mm Hg; P=0.0002), and higher pulmonary capillary wedge pressure (17±5 versus 9±3 mm Hg; P=0.0001). However, LV transmural pressure (pulmonary capillary wedge pressure-right atrial pressure), which reflects LV preload independent of right heart congestion and pericardial restraint, was similar in TR and controls (6±3 versus 4±2 mm Hg; P=0.3). With exercise, TR subjects displayed lower peak VO2 (10.3±2.8 versus 13.8±4.2 mL/min per kg; P=0.02), lower pulmonary blood flow (6.4±1.3 versus 10.3±3.3 L/min; P=0.001), and less increase in pulmonary blood flow relative to VO2 (+4.6±1.1vs +6.2±0.7; P=0.001). TR subjects displayed higher pulmonary capillary wedge pressure with exercise, but this was solely because of RA hypertension (27±9 versus 8±3 mm Hg; P<0.0001), because LV transmural pressure dropped with exercise in subjects with TR (-5±6 versus +3±3 mm Hg; P=0.0007), suggesting inadequate LV diastolic filling, despite high pulmonary capillary wedge pressure. Impaired exercise capacity in people with severe TR is related to low cardiac output reserve relative to metabolic needs, coupled with elevated systemic and pulmonary venous pressures. Left heart pressures are elevated with exercise in subjects with TR, despite low LV preload, secondary to enhanced ventricular interaction.

OP22.04: Low pulmonary blood flow demonstrated by Doppler and MRI in late onset IUGR

<scp>OP</scp>22.04: Low pulmonary blood flow demonstrated by Doppler and <scp>MRI</scp> in late onset <scp>IUGR</scp>

Intrauterine inflammation alters cardiopulmonary and cerebral haemodynamics at birth in preterm lambs

Intrauterine inflammation is associated with preterm birth and poor long-term cardiopulmonary outcomes. We aimed to determine the effect of intrauterine inflammation on the cardiopulmonary and cerebral haemodynamic transition at birth, and the response to subsequent haemodynamic challenge. Fetal instrumentation was performed at ∼112 days gestation (term is 147 days) for measurement of cardiopulmonary and cerebral haemodynamics. At 118 days, inflammation was induced by intra-amniotic administration of lipopolysaccharide (LPS; n = 7); controls (n = 5) received intra-amniotic saline. At 125 days lambs were delivered and mechanically ventilated. Arterial blood gases, pulmonary and systemic arterial blood pressures and flows were measured during the perinatal period. At 10 min a haemodynamic challenge was administered by increasing positive end-expiratory pressure. During the first 10 min after birth, LPS-exposed lambs had higher pulmonary vascular resistance and lower pulmonary blood flow and left ventricular output than controls. Carotid arterial blood flow was higher in LPS-exposed lambs than controls between 3 and 7 min after delivery, and cerebral oxygen delivery was higher at 5 min. During the haemodynamic challenge, pulmonary blood flow and left ventricular output were reduced in controls but not in LPS-exposed lambs; a transient reduction in brachiocephalic arterial pressure occurred in LPS-exposed lambs but not in controls. Intrauterine inflammation altered the cardiopulmonary and cerebral haemodynamic transition at birth and reduced the cardiopulmonary response to a haemodynamic challenge after birth. The transient reduction in brachiocephalic arterial pressure suggests intrauterine inflammation may alter cerebrovascular control following an increase in positive end-expiratory pressure.

Systemic hypertension in an infant with unrepaired tetralogy of Fallot: case report

Patients with severe right ventricular outflow tract obstruction in tetralogy of Fallot typically have right-to-left shunting, resulting in low pulmonary blood flow and cyanosis. Here we present the case of an infant with tetralogy of Fallot and severe pulmonary valve stenosis, complicated by systemic hypertension, the presence of which altered flow dynamics and possibly prevented cyanosis.

Quantitative pulmonary perfusion imaging at 3.0 T of 2-year-old children after congenital diaphragmatic hernia repair: initial results

To investigate whether dynamic contrast-enhanced MR imaging of the lung following congenital diaphragmatic hernia repair is feasible at 3.0 T in 2-year-old children and whether associated lung hypoplasia (reflected in reduced pulmonary microcirculation) can be demonstrated in MRI. Twelve children with a mean age 2.0 ± 0.2 years after hernia repair underwent DCE-MRI at 3.0 T using a time-resolved angiography with stochastic trajectories sequence. Quantification of lung perfusion was performed using a pixel-by-pixel deconvolution approach. Six regions of interest were placed (upper, middle and lower parts of right and left lung) to assess differences in pulmonary blood flow (PBF), pulmonary blood volume (PBV) and mean transit time (MTT) while avoiding the inclusion of larger pulmonary arteries and veins. The difference in PBF and PBV between ipsilateral and contralateral lung was significant (P < 0.5). No significant differences could be detected for the MTT (P = 0.5). DCE-MRI in 2-year-old patients is feasible at 3.0 T. Reduced perfusion in the ipsilateral lung is reflected by significantly lower PBF values compared with the contralateral lung. DCE-MRI of the lung in congenital diaphragmatic hernia can help to characterise lung hypoplasia initially and in the long-term follow-up of children after diaphragmatic repair. Congenital diaphragmatic hernia often leads to lung hypoplasia and secondary pulmonary hypertension. Dynamic contrast-enhanced 3-T magnetic resonance can assess these complications in 2-year-olds. The affected ipsilateral lung shows reduced perfusion and lower pulmonary blood flow. Thoracic DCE-MRI helps characterise lung hypoplasia in children after hernia repair.