Platelet Distribution Width and Mean Platelet Volume in Children With Pulmonary Arterial Hypertension Secondary to Congenital Heart Disease With Left-to-Right Shunt: New Indices of Severity?

The majority of patients with congenital heart disease (CHD), particularly those with relevant systemic-to-pulmonary shunts, if left untreated, will experience the development of pulmonary arterial hypertension (PAH). Previous studies have shown that platelet activation occurs in patients with PAH. In response, this study aimed to investigate the platelet indices, including platelet distribution width (PDW) and mean platelet volume (MPV), in patients with PAH. The study was conducted in the pediatrics cardiology unit of Selcuk University Medical Faculty between July 2010 and January 2012. The patients’ clinical and laboratory data were obtained retrospectively from hospital recordings. The study enrolled 57 children with CHD (all with left-to-right shunting). The patients who had undergone diagnostic cardiac catheterization were analyzed according to the presence or absence of PAH. Group 1 had CHD with PAH, and group 2 had CHD without PAH. Compared with the group 2 patients, a significant decrease in PDW (p < 0.0001) was noted in the group 1 patients (with PAH). Likewise, a significant difference was found in the MPV of group 1 (p < 0.0001). Statistically, groups 1 and 2 did not differ in terms of platelet count (p = 0.3). Patients who had pulmonary hypertension secondary to CHD with left-to-right shunting exhibited a lower PDW and MPV.     

L—精氨酸对高肺血流量所致肺动脉高压的防治作用

目的 探讨L－精氨酸对高肺血流量所致肺动脉高压的防治作用。方法 21只雄性SD大鼠随机分为对照组（n=6)、分流组（n=7)和分流＋L－精氨酸组（n=8)。对分流组和分流＋L－精氨酸组大鼠行腹主动脉－下腔静脉分流术。11周后以右心导管法测定肺动脉平均压（mPAP)。检测右心室／体重（RV／BW）和右心室／左心室＋室间隔（RV/LV S)比值。并且观测肺血管结构的变化。结果 分流组大鼠mPAP、RV／BW及RV/(LV S）比值明显高于对照组（P均＜0．01）,且分流组大鼠肺小血管肌化程度明显增强,肺中、小肌型动脉相对中膜面积及厚度明显增加。而分流＋L－精氨酸组大鼠mPAP、RV／BW及RV／LV＋S比值明显低于分流组（P均＜0．05）,L－精氨酸缓解了肺血管结构重建的形成。结论 L－精氨酸对高肺血流量所致肺血管结构重建及肺动脉高压有重要的调节作用。     

Bidirectional shunt flow across a ventricular septal defect: Pulsed doppler echocardiographic analysis

Pulsed Doppler echocardiographic and hemodynamic examinations were performed in 31 patients (mean age 17.8 years) with isolated ventricular septal defect (VSD). Three groups were studied: group I (n=6) patients had severe pulmonary vascular obstructive disease (PVOD); group II (n=12) patients had pulmonary hypertension (PH) without severe PVOD; group III (n=13) patients had no PH. Bidirectional shunting was detected in 9 VSD patients (6 in group I and 3 in group II). Patients with low to moderately elevated right ventricular pressures demonstrated left-to-right shunting across the defect throughout the cardiac cycle. When systolic pressure in the right ventricle reached approximately 60% of the left ventricular pressure, right-to-left shunting occurred across the defect during early and mid diastole. However, in patients with Eisenmenger syndrome (group I) the right-to-left shunting occurred during late systole with continuation during the early and mid diastolic period. The earlier occurrence of right-to-left shunting (index <0.5 second) signifies the presence of severe PVOD.     

Sitaxsentan for the prevention of experimental shunt-induced pulmonary hypertension

We previously reported on the partial prevention of experimental shunt-induced pulmonary arterial hypertension (PAH) by the nonselective endothelin (ET) ET-A/ET-B receptor antagonist bosentan. As the respective roles of the ET-A and ET-B receptor signaling in the pathobiology of the disease remain undefined, we investigated the effects of selective ET-A receptor blockade by sitaxsentan in the same early stage PAH model. Twenty-one 3-wk-old piglets were randomized to placebo or sitaxsentan therapy (1.5 mg/kg/d), after anastomosis of the left subclavian artery to the pulmonary arterial trunk or after a sham operation. Three months later, the animals underwent a hemodynamic evaluation, followed by pulmonary tissue sampling for morphometry and real-time-quantitative-PCR for ET-1, angiopoietin-1, and bone morphogenetic receptor (BMPR) signaling molecules. Three months of left to right shunting induced an increase in pulmonary vascular resistance (PVR) and medial thickness, an overexpression of ET-1, ET-B receptor, and angiopoietin-1, and a decreased expression of BMPR-2 and BMPR-1A. Pretreatment with sitaxsentan prevented shunt-induced increase in PVR and decreased medial thickness by 64%. Sitaxsentan therapy completely prevented the decreased expression of BMPR-2 and limited the overexpression of ET-1, ET-B and angiopoietin-1, and the decreased expression of BMPR-1A. In conclusion, selective ET-A receptor blockade partially prevents shunt-induced PAH.     

高肺血流量对肺血管结构及内源性硫化氢影响

目的 探讨高肺血流量所致肺动脉高压(PH)大鼠肺血管结构和血浆硫化氢的变化。方法 雄性SD大鼠共16只。对分流组大鼠行腹主动脉、下腔静脉分流术;11周后以右心导管法测定肺动脉平均压(mPAP);检测右心室/体重(RV/BW)和右心室/左心室+室间隔(RV/LV+S)比值;并以光学显微镜和电子显微镜观测肺血管结构变化;以分光光度法测定血浆硫化氢含量。结果 分流组大鼠mPAP、RV/BW及RV/(LV+S)比值均明显高于对照组(P均<0.01);光镜下肺小血管肌化程度明显增强,肺中、小肌型动脉相对中膜厚度明显增加;电镜下,肺中、小肌型动脉内皮细胞增生、肥厚、肿胀,平滑肌细胞增生、肥厚,并由收缩表型向合成表型转化。分流组大鼠的血浆H_2S含量明显低于对照组,肺动脉平均压与血浆硫化氢含量呈负相关。结论 肺血管结构重建是高肺血流量所致PH重要病理基础,内源性H_2S下调可能在其形成中起重要作用。     

儿童肺血管疾病的影像学诊断

肺血管疾病是一组累及包括各级肺动、 静脉及肺毛细血管在内的肺循环疾病, 其致病因素各异, 病理改变多样。儿童与成人肺血管疾病从致病因素、 发病机制、 病理生理学, 临床表现及预后等方面均存在较大差异。儿童肺血管性疾病包括以下几大类别： （1）先天性肺血管病变,包括各级别的肺动、 静脉畸形、 肺毛细血管发育异常、 气管支气管畸形伴肺血管畸形、 血管淋巴异常等; （2）肺血管栓塞性病变, 包括炎症性栓塞, 肿瘤性栓塞; （3）肺血管炎性病变; （4）肺动脉高压性病变; （5） 肺部血管源性肿瘤。儿童常见肺血管疾病常用的影像学检查方法有胸部X线平片、 超声心动图、 胸部CT增强扫描、 肺血管造影检查、 核医学肺通气/灌注显像等。该文对上述儿童常见肺血管疾病影像学检查方法的选择及影像学诊断要点进行概述。     

影响左向右分流型先心病新生儿撤机成功的多因素分析

目的研究不同因素对左向右分流型先心病新生儿呼吸机撤离(简称撤机)成功率的影响。方法收集左向右分流型先心病机械通气新生儿95例,定义48 h内无需重新插管者属撤机成功。以撤机成功率为因变量,以新生儿胎龄、体重、肺动脉压力水平、肺血流量、缺损大小、缺损类型、合并心衰、肺炎为自变量进行多元线性逐步回归,筛选出可能的影响因素,进一步研究不同影响因素对撤机成功率的影响。结果肺动脉压力、肺血流量大小和缺损类型是影响撤机成功率的重要因素(P均<0．05)。中重度肺动脉高压组的撤机成功率低于轻度肺动脉高压组(P均<0．05),差异有统计学意义。高肺血流量组的撤机成功率低于无高肺血流量组(P均<0．05),差异有统计学意义。联合缺损组的撤机成功率低于单纯缺损组(P均<0．05),差异有统计学意义。结论肺动脉压、肺血流量、缺损类型是影响撤机成功率的重要因素。     

Abnormal vascular tone in infants and children with lung hypoplasia: Findings from cardiac catheterization and the response to chronic therapy.

OBJECTIVE: We describe four cases of chronic pulmonary hypertension in infants and children with chronic lung disease and pulmonary hypoplasia due to severe congenital diaphragmatic hernia (CDH) or congenital cystic adenomatoid malformation (CCAM). We report data from cardiac catheterization under various conditions: baseline respiratory support and room air, hyperoxic and inhaled nitric oxide challenge. We further report cardiac catheterization measures after chronic pulmonary vasodilator therapy with sildenafil alone or a combination of sildenafil and inhaled nitric oxide (three patients). DESIGN: Case series. SETTING: Tertiary academic center. PATIENTS: Infants and children ages 0-11 yrs with CDH (n = 3) or CCAM (n = 1) with evidence of chronic pulmonary hypertension by echocardiogram and cor pulmonale (n = 3). INTERVENTIONS: Catheterization and pulmonary vasodilator therapy. MEASUREMENTS AND MAIN RESULTS: Pulmonary vascular resistance, pulmonary arterial pressure, and changes in these measures were assessed. A 20% change in pulmonary vascular resistance was considered a clinically significant response. Ten catheterizations were performed in four patients. All patients had elevated pulmonary vascular resistance and pulmonary arterial pressures at initial catheterizations and significant vasodilation during inhaled nitric oxide. CONCLUSIONS: Chronic lung disease following pulmonary hypoplasia from CDH and CCAM is associated with abnormal pulmonary vascular tone in infants and children with evidence of chronic pulmonary hypertension. Chronic pulmonary vasodilator therapy may improve pulmonary vascular function and enhance lung growth in infants and children who are treated during their period of potential for rapid lung growth.     

肺动脉高压病因学最新研究进展

肺动脉高压(pulmonary arterial hypertension,PAH)是一组少见的、预后不良的疾病,以进行性增高的肺动脉压力和阻力为特征.其病理变化包括肺血管收缩与重构、肺血管平滑肌和内皮细胞的异常增殖、血栓形成等.PAH的发病机制复杂,最新研究表明肺动脉高压病因包括骨形成蛋白Ⅱ型受体(BMPR2)和活化素受体样激酶(ALK1)等遗传基因变异以及过氧化物酶增殖物激活受体(PPAR)、Rho激酶信号通路等的异常.这为肺动脉高压的治疗和预防提供了更多的理论依据.     

钙通道在肺动脉高压发病机制中的研究进展

肺动脉高压是一类严重的进展性疾病,最终导致患者右心衰竭,甚至死亡。肺血管收缩、肺血管重构、血栓形成和血管硬化等诸多原因导致肺动脉高压的发生。众多研究表明,Ca~(2+)信号在维持血管张力和调控血管平滑肌细胞增殖、凋亡等过程中发挥了重要作用,而这一信号转导机制主要由钙通道来调节操纵。文章综述钙通道在肺动脉高压发病机制中的研究进展。     

Fatal pulmonary arterial hypertension in an infant girl with incontinentia pigmenti

We report the case of an infant girl with incontinentia pigmenti (IP) complicated by fatal pulmonary arterial hypertension (PAH). She was diagnosed with IP, based on the presence of specific skin lesions, neonatal seizures, hypereosinophilia and a maternal family history of IP. At the age of 2 months, she was diagnosed with PAH on systolic heart murmur due to tricuspid valve regurgitation. Despite several treatments for PAH but not including epoprostenol, severe PAH persisted and she died of pulmonary hypertensive crisis at the age of 5 months. On postmortem histopathology the pulmonary artery had severe intimal thickening, with occlusion or stenosis of the vascular lumen of the small pulmonary arteries as well as partial plexiform lesions, all of which were compatible with PAH. Modulation of nuclear factor‐κB signaling may be involved in the development of PAH in IP.     

Congenital Hepatic Arteriovenous Malformation Presenting with Severe Persistent Pulmonary Hypertension

Congenital hepatic arteriovenous malformation is a rarely seen vascular malformation with persistent pulmonary hypertension in neonates. The authors report a full-term female newborn presenting with intractable heart failure and respiratory distress soon after birth. Investigation by echocardiography showed severe persistent pulmonary hypertension of the newborn and patent ductus arteriosus. The hepatic angiogram revealed congenital hepatic arteriovenous malformation; therefore, secondary pulmonary artery hypertension complicated with ‘steal’ phenomenon was conclusively diagnosed.     

Elusive Pulmonary Venous Confluence-to-Hepatic Vein Connection Leading to Heart Failure

A persistent omphalomesenteric vein (POMV) maintaining a link between the pulmonary venous system and the infracardiac hepatic venous system can lead to significant left-to-right shunting. To the best of the authors’ knowledge, POMV causing significant left-to-right shunting has been unreported previously, especially in association with type B interrupted aortic arch. This report describes this association in a child who had chronic heart failure even after successful repair of interrupted aortic arch and ventricular septal defect. Subsequent percutaneous device closure of the POMV using an Amplatzer vascular plug II led to resolution of the child’s heart failure.     

Pulmonary hypertension in congenital diaphragmatic hernia

Clinically significant pulmonary hypertension (PHTN) is a common finding in newborn infants with congenital diaphragmatic hernia (CDH) resulting in right to left shunting at pre- and postductal level, hypoxemia, and acute right heart failure in those most severely affected. Even in those without clinical manifestations of ductal shunting, cardiac echo studies would suggest that increased pulmonary vascular resistance and right ventricular pressures are almost a universal finding in this disease, and in some instances, may persist well into the postnatal period. The lung is small and structurally abnormal, and the pulmonary vascular bed is not only reduced in size, but responds abnormally to vasodilators. During the last 20 years, "gentle" ventilation, delayed surgery, and improved peri-operative care have made the greatest impact in decreasing mortality in this condition. Use of PGE1 should be considered early if there is hemodynamically significant PHTN, right ventricular dysfunction, and the patent ductus arteriosus (PDA) is becoming restrictive. In individual patients, inhaled nitric oxide (iNO) might be helpful, but the response to iNO should be confirmed using echocardiography. In patients who survive operation and leave the hospital, there are chronic causes of morbidity that need to be looked for and managed in a multi-disciplinary follow-up clinic.     

骨髓间充质干细胞移植对肺动脉高压大鼠肺血管重构的影响

目的 探讨骨髓间充质干细胞(MSCs)移植对野百合碱诱导的肺动脉高压(PAH)大鼠肺血管重构的影响.方法 体外分离、培养并纯化SD大鼠骨髓MSCs.健康雄性SD大鼠随机分为3组:正常对照组(n＝15)、PAH组(n＝20)和MSCs移植组(n＝20).PAH组和MSCs移植组大鼠一次性项背部皮下注射野百合碱(50 mg·kg -1),复制PAH肺血管重建动物模型.3组大鼠在同等条件下饲养.3周后,MSCs移植组大鼠经舌下静脉注射5×109 L-1的经Hoechst 33342标记的MSCs细胞悬液1 mL,PAH组大鼠予等量低糖-Dulbecco改良Eagle's培养液(L-DMEM)注射,正常对照组不做任何处理.移植28 d,观察3组大鼠肺小动脉的显微结构及超微结构的改变.结果 PAH大鼠用MSCs移植28 d后,肺小动脉管壁厚度指标(WD/TD％、VA％)、放射性肺泡计数、肺非肌性小动脉肌化程度均较PAH组显著改善(P＜0.01)；其肺小动脉的重构及超微结构的血气屏障、线粒体、板层小体等改变均有明显改善.荧光显微镜观察到Hoechst 33342标记的MSCs在肺内定植,且分化成大量新生血管并形成侧支循环,肺动脉重构得到有效逆转.结论 MSCs移植可有效减轻并逆转肺动脉重构的进程,其作用机制是MSCs分化形成新生血管,建立了侧支循环,从而修复野百合碱诱导的肺损伤.     

Morphological Studies of Pulmonary Arteriovenous Shunting in a Lamb Model of Superior Cavopulmonary Anastomosis

We sought to identify and characterize the abnormal vascular structures responsible for pulmonary arteriovenous shunting following the Glenn cavopulmonary shunt. Superior cavopulmonary shunt is commonly performed as part of the staged pathway to total cavopulmonary shunt to treat univentricular forms of congenital heart disease, however, clinically significant pulmonary arteriovenous malformations develop in some patients after the procedure. The causes of pulmonary arteriovenous malformations and other pulmonary vascular changes that occur after cavopulmonary shunt are not known. Using a juvenile lamb model of superior cavopulmonary anastomosis that reliably produces pulmonary arteriovenous malformations, we performed echocardiography and morphological analyses to determine the anatomic site of shunting and to identify the vascular structures involved. Pulmonary arteriovenous shunting was identified by contrast echocardiography in all surviving animals (n = 40) following superior cavopulmonary anastomosis. Pulmonary vascular corrosion casts revealed abnormal tortuous vessels joining pulmonary arteries and veins in cavopulmonary shunt animals but not control animals. In conclusion, unusual channels that bridged pulmonary arteries and veins were identified. These may represent the vascular structures responsible for arteriovenous shunting following the classic Glenn cavopulmonary shunt. Detailed analysis of these structures may elucidate factors responsible for their development.     

Clinical characteristics of pulmonary arterial hypertension associated with Down syndrome

The genetic abnormalities associated with Down syndrome (DS) are still being identified. Few studies have examined the roles of CRELD1 and GATA4 in cardiac abnormalities or their association with pulmonary artery histopathology. Children with DS have an elevated risk of pulmonary arterial hypertension (PAH). This increased risk is likely mainly due to genetic background, the structural characteristics of the pulmonary vascular wall, and certain heart diseases and partly due to pulmonary hypoplasia, upper and lower airway obstructive diseases, chronic infection, and neuromuscular underdevelopment. Exposure to increased left‐to‐right shunt flow increases sheer stress on endothelium and may induce endothelial dysfunction followed by irreversible remodeling of pulmonary arteries. Pathologic changes include endothelial cell proliferation and thickening of the pulmonary arterial wall due to mechanical responses to the thinner medial smooth muscle cell layer, which includes underdevelopment of alveoli. Production of prostacyclin and nitric oxide is diminished in DS, but endothelin‐1 and thromboxane are elevated. Perioperatively, patients with DS may experience pulmonary hypertensive crisis after intracardiac repair and prolonged PAH, and have a poorer response to nitric oxide inhalation. To better manage DS, it is crucial to systematically evaluate the systemic complications of DS. Cardiac catheterization data, particularly those regarding pulmonary arterial resistance, are essential in assessing severity and response to vasodilating agents, preventing postoperative crisis, and evaluating the possibility of intracardiac repair. Advanced therapy with pulmonary vasodilating agents appears effective. Operative risk is similar for individuals with and without DS, except among patients with a complete atrioventricular canal defect.     

先天性心脏病肺动脉高压手术前后右心功能变化和治疗

目的 了解先天性心脏病左向右分流导致的重度肺动脉高压对右心功能的影响以及手术矫治后右心功能的恢复状态。方法 对室间隔缺损(室缺)合并重度肺动脉高压(全肺循环阻力增加)的40例患儿，用心导管的方法进行术前、术后5～7年右心功能、肺循环的血流动力学随访测定。结果 术前右心心搏指数、作功指数、心排指数显著高于术后；术前右房压、右室收缩压及舒张压、肺动脉压力和阻力均增高，缺损修补后右室舒张压恢复正常，收缩压的降低与肺动脉压力下降有关；大型室缺左向右分流重度肺动脉高压右心功能不全系继发性右室高排出量心力衰竭，且伴有舒张功能障碍。结论 治疗心力衰竭不宜首选正性心肌收缩药物；降低肺动脉压力、减少左向右分流、根治心内畸形是合理的选择；术后右室收缩压持续不能恢复至正常水平，提示继发性肺血管梗阻性病变存在。     

The hemodynamic effects of intrauterine hypoxia: an experimental model in newborn lambs.

An experimental animal model of intrauterine hypoxia and respiratory distress in newborn lambs was produced by inducing maternal hypotension. Serial hemodynamic data indicated that the oxygenation defect in the lambs was due to right-to-left shunting of blood through fetal channels rather than within the lungs. Shunting was mainly across the foramen ovale, but, in severely distressed animals, significant right-to-left shunt also occurred through the ductus arteriosus. Left-to-right shunts across the ductus arteriosus were found in lambs with milder respiratory distress. The implications of perinatal hypoxia as it affects the pulmonary vascular bed in human neonates with the respiratory distress syndrome (hyaline membrane disease) and persistence of the fetal circulation are discussed. It is speculated that the early pulmonary vascular esponses in the two diseases may be identical.     

肺动脉去神经治疗肺动脉高压研究进展

肺动脉去神经治疗(pulmonary artery denervation,PADN)可阻断局部肺动脉交感神经,降低肺动脉高压(pulmonary arterial hypertension,PAH)血流动力学参数,改善肺血管重塑及右心室心肌肥厚、纤维化,进而改善心室功能。前期基础实验已确定肺动脉交感神经在肺动脉内膜位置,并证实PADN对PAH动物模型安全有效,可能通过抑制交感神经系统和肾素-血管紧张素-醛固酮系统发挥作用。PADN已开展成人临床应用研究,取得良好临床效果。在此基础上正初步探索PADN在儿童PAH中应用的可能性。