Per-operative stent placement in the right pulmonary artery; a hybrid technique for the management of pulmonary artery branch stenosis at the time of pulmonary valve replacement in adult Fallot patients

After having undergone surgical correction at an early age, many patients with tetralogy of Fallot develop long-term complications including progressive pulmonary regurgitation and peripheral pulmonary stenosis. A high percentage of these patients need to undergo a second operation in their adolescence or early adulthood. If simultaneous treatment of both pulmonary regurgitation and peripheral pulmonary stenosis is warranted, a complete surgical approach has several disadvantages. We describe four cases of Fallot patients with severe pulmonary regurgitation and peripheral pulmonary stenosis who were treated using a hybrid approach involving surgical implantation of a pulmonary homograft and peroperative stenting of the pulmonary artery.     

The outcome of pulmonary hypertension and its association with pulmonary artery dilatation

Background

Pulmonary artery (PA) dilatation is often seen in pulmonary hypertension (PH) and is considered a long-term consequence of elevated pressure. The PA dilates over time and therefore may reflect disease severity and duration. Survival is related to the stage of the disease at the time of diagnosis and therefore PA diameter might be used to predict prognosis. This study evaluates the outcome of patients with pulmonary arterial hypertension (PAH) and chronic thrombo-embolic pulmonary hypertension (CTEPH) and investigates whether PA diameter at the time of diagnosis is associated with mortality.

Methods

Patients visiting an outpatient clinic of a tertiary centre between 2004 and 2018 with a cardiac catheterisation confirmed diagnosis of PAH or CTEPH and a CT scan available for PA diameter measurement were included. PA diameter and established predictors of survival were collected (New York Heart Association (NYHA) class, N‑terminal pro-brain natriuretic peptide (NT-proBNP) level and 6‑min walking distance (6MWD)).

Results

In total 217 patients were included (69% female, 71% NYHA class ≥III). During a median follow-up of 50 (22–92) months, 54% of the patients died. Overall survival was 87% at 1 year, 70% at 3 years and 58% at 5 years. The mean PA diameter was 34.2 ± 6.2 mm and was not significantly different among all the diagnosis groups. We found a weak correlation between PA diameter and mean PA pressure ( r = 0.23, p < 0.001). Male sex, higher age, shorter 6MWD and higher NT-proBNP level were independently associated with mortality, but PA diameter was not.

Conclusion

The prognosis of PAH and CTEPH is still poor. Known predictors of survival were confirmed, but PA diameter at diagnosis was not associated with survival in PAH or CTEPH patients.

     

Bicuspid stenotic aortic valves: clinical characteristics and morphological assessment using MRI and echocardiography

Background

Bicuspid aortic valve (BAV) is one of the most common congenital heart defects with a population prevalence of 0.5% to 1.3%. Identifying patients with BAV is clinically relevant because BAV is associated with aortic stenosis, endocarditis and ascending aorta pathology.

Methods and Results

Patients with severe aortic stenosis necessitating aortic valve replacement surgery were included in this study. All dissected aortic valves were stored in the biobank of the University Medical Centre Utrecht. Additionally to the morphological assessment of the aortic valve by the surgeon and pathologist, echocardiographic and magnetic resonance imaging (MRI) images were evaluated. A total of 80 patients were included of whom 32 (40%) were diagnosed with BAV by the surgeon (gold standard). Patients with BAV were significantly younger (55 vs 71 years) and were more frequently male. Notably, a significant difference was found between the surgeon and pathologist in determining valve morphology. MRI was performed in 33% of patients. MRI could assess valve morphology in 96% vs 73% with echocardiography. The sensitivity of MRI for BAV in a population of patients with severe aortic stenosis was higher than echocardiography (75% vs 55%), whereas specificity was better with the latter (91% vs 79%). Typically, the ascending aorta was larger in patients with BAV.

Conclusion

Among unselected patients with severe aortic valve stenosis, a high percentage of patients with BAV were found. Imaging and assessment of the aortic valve morphology when stenotic is challenging.     

Strategies for biological heart valve replacement: Stentless xenografts fail to evolve into an alternative pulmonary valve substitute in a Ross procedure

The Ross operation is a complex procedure for aortic valve replacement in which the pulmonary autograft is replaced by a homograft. However, homograft availability is becoming limited. This report evaluates the performance of porcine stentless prostheses as alternative pulmonary substitutes. Echocardiographic results from two patient cohorts were compared at time of discharge and 1 year after a Ross procedure. Thirty-three patients (median age 42 years, range 17–62 years, 76% male) received a stentless prosthesis (median size 25.6 mm, range 25–29 mm) for right ventricular outflow tract reconstruction. Clinical data were not significantly different from 106 patients (median age 47 years, range 2–68 years, 75% male) who received cryopreserved homografts (median size 26 mm, range 20–33 mm). At time of discharge, peak pressure gradients (ΔP_max) across the stentless valve (median ΔP_max 13 mmHg, range 2–26 mmHg) were higher compared to homografts (median ΔP_max 7 mmHg, range 1–32 mmHg, p<0.001). At 1 year, gradients increased in both groups, but were significantly higher across stentless valves (median ΔP_max 23 mmHg, range 10–81 mmHg vs. median ΔP_max 13 mmHg, range 2–74 mmHg, p<0.001). Eleven patients (33%) in the stentless-valve group were classified “at risk” with a ΔP_max of ≥30 mmHg. Four of them (12%) had to be re-operated. In conclusion, stentless valves showed higher pressure gradients and their performance was inferior to cryopreserved homografts. See accompanying commentary by Ulrich Stock DOI: 10.1002/biot.201200341     

Distribution of the pulmonary artery and vein in the chimpanzee lung

Lungs of two chimpanzees (Pan troglodytes) were examined. The right pulmonary artery runs across the ventral side of the right upper lobe bronchiole and, then across the dorsal side of the right middle lobe bronchiole. Thereafter, it runs between the dorsal bronchiole system and the lateral bronchiole system, along the right bronchus. During its course, it gives off arterial branches which run along each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole and then between the dorsal bronchiole system and the lateral bronchiole system. The branches of the pulmonary artery run mainly along the dorsal or lateral side of the bronchiole. The pulmonary veins run mainly along the ventral or medial side of the bronchioles, and between them. Finally, they enter the left atrium with four large veins, i.e. the common trunk of the right upper lobe vein and the right middle lobe vein, right lower lobe pulmonary venous trunk, left middle lobe vein, and left lower lobe pulmonary venous trunk.     

Distribution of the pulmonary artery and vein of the orangutan lung

The distribution of the pulmonary artery and vein of the orangutan lung was examined. The right pulmonary artery runs obliquely across the ventral side of the right bronchus at the caudally to the right upper lobe bronchiole. It then runs across the dorsal side of the right middle lobe bronchiole. Thereafter it runs obliquely across the dorsal side of the right bronchus, and then along the dorso-medial side of the right bronchus. This course is different from that in other mammals. During its course, it gives off branches which run mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole, then along the dorso-lateral side of the left bronchus, giving off branches which run along each bronchiole. The pulmonary veins run mainly the ventral or medial side of, along or between the bronchioles. In the left lung, the left middle lobe vein has two trunks; one enters the left atrium, and the other enters the left lower lobe pulmonary venous trunk. This is also different from that found in most mammals. Finally, the pulmonary veins enter the left atrium with four large veins.     

Glioblastomas and brain metastases differentiation following an MRI texture analysis-based radiomics approach

PurposeTo evaluate the potential of 2D texture features extracted from magnetic resonance (MR) images for differentiating brain metastasis (BM) and glioblastomas (GBM) following a radiomics approach.MethodsThis retrospective study included 50 patients with BM and 50 with GBM who underwent T1-weighted MRI between December 2010 and January 2017. Eighty-eight rotation-invariant texture features were computed for each segmented lesion using six texture analysis methods. These features were also extracted from the four images obtained after applying the discrete wavelet transform (88 features × 4 images). Three feature selection methods and five predictive models were evaluated. A 5-fold cross-validation scheme was used to randomly split the study group into training (80 patients) and testing (20 patients), repeating the process ten times. Classification was evaluated computing the average area under the receiver operating characteristic curve. Sensibility, specificity and accuracy were also computed. The whole process was tested quantizing the images with different gray-level values to evaluate their influence in the final results.ResultsHighest classification accuracy was obtained using the original images quantized with 128 gray-levels and a feature selection method based on the p-value. The best overall performance was achieved using a support vector machine model with a subset of 32 features (AUC = 0.896 ± 0.067, sensitivity of 82% and specificity of 80%). Naïve Bayes and k-nearest neighbors models showed also valuable results (AUC ≈ 0.8) with a lower number of features (<13), thus suggesting that these models may be more generalizable when using external validations.ConclusionThe proposed radiomics MRI approach is able to discriminate between GBM and BM with high accuracy employing a set of 2D texture features, thus helping in the diagnosis of brain lesions in a fast and non-invasive way.     

增殖细胞核抗原在低氧大鼠肺动脉平滑肌细胞中表达

目的通过建立低氧性肺动脉高压大鼠模型,探讨增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)在大鼠低氧性肺血管平滑肌细胞中的表达。方法将SPF级SD大鼠随机分为正常对照组(n=10)、模型组(n=10),通过间断常压低氧法建立大鼠低氧性肺动脉高压模型,肺组织切片经HE染色后图像分析技术定量检测大鼠肺小动脉的形态改变;免疫组织化学染色法测定肺血管平滑肌细胞内PCNA蛋白表达,并经图像分析半定量检测其表达强度。结果 4周后,模型组SD大鼠MT%、MA%与对照组比较,差异具有显著性(P<0.05);模型组SD大鼠肺血管平滑肌细胞内PCNA核蛋白表达(积分面积、累积光密度)与对照组比较,差异具有显著性(P<0.05)。结论常压低氧4周可成功建立肺动脉高压大鼠模型,PCNA在肺血管平滑肌细胞中的表达量具有差异性提示其可能在肺动脉高压形成过程中起重要作用。     

Distribution of the pulmonary artery and vein in the lung of the white handed gibbon

The lungs of four white handed gibbons (Hylobates agilis) were examined. The right pulmonary artery runs across the ventral side of the right upper lobe bronchiole, and then traverses the dorsal side of the right middle lobe bronchiole. Thereafter, it runs along the dorso-lateral side of the right bronchus, between the dorsal bronchiole system and the lateral bronchiole system, and gradually follows the dorsal side of the right bronchus. During its course, it gives off arterial branches which run along each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole and then along the left bronchus as in the right lung. The branches of the pulmonary artery run mainly along the dorsal or lateral side of the bronchiole, while the pulmonary veins run mainly the medial side of the bronchioles or between them. However, in a few portions, the pulmonary veins run the lateral side of the bronchioles. Finally, they enter the left atrium with four large veins i.e. the common trunk of the right upper lobe vein and right middle lobe vein, right lower lobe pulmonary venous trunk, left middle lobe vein, and left lower lobe pulmonary venous trunk.     

Preparation, characterization and in vivo assessment of Gd-albumin and Gd-dendrimer conjugates as intravascular contrast-enhancing agents for MRI

We report in vivo and in vitro MRI properties of six gadolinium-dendrimer and gadolinium-albumin conjugates of derivatized acyclic diethylenetriamine-N,N′,N′,N″, N″-pentaacetic acid (1B4M) and macrocyclic 1,4,7,10-tetraazacyclododecane-N,N′,N″,N?-tetraacetic acid (C-DOTA). The three albumin-based agents have comparable protein to chelate ratios (1:16-18) as well as molar relaxivity (8.8-10.4 mM^− 1 s^− 1). The three dendrimer based agents have blood clearance half-lives ranging from 17 to 66 min while that of the three albumin-based agents are comparable to one another (40-47 min). The dynamic image obtained from use of the albumin conjugate based on the macrocycle (C-DOTA) showed a higher contrast compared to the remaining two albumin based agents. Our conclusion from all of the results is that the macrocyclic-based (DOTA) agents are more suitable than the acyclic-based (1B4M) agent for in vivo use based on their MRI properties combined with the kinetic inertness property associated with the more stable Gd(III) DOTA complex.     

Higher critical plaque wall stress in patients who died of coronary artery disease compared with those who died of other causes: A 3D FSI study based on ex vivo MRI of coronary plaques

Mechanical forces play an important role in the rupture of vulnerable plaques. This process is often associated with cardiovascular syndromes, such as heart attack and stroke. In this study, magnetic resonance imaging (MRI)-based models were used to investigate the association between plaque wall stress (PWS) and coronary artery disease (CAD).     

Distribution of the pulmonary artery and vein in the lung of the crab-eating monkey (Macaca fascicularis)

In the lung of the crab-eating monkey (Macaca fascicularis), the right pulmonary artery runs across the ventral side of the right upper lobe bronchiole and the dorsal side of the right middle lobe bronchiole. Thereafter, it courses along the dorso-lateral side of the right bronchus, between the dorsal and lateral bronchiole systems. During this course, the right pulmonary artery gives off arterial branches running mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole, and is then distributed as in the right lower lobe. The pulmonary veins run mainly along the ventral or medial side of the bronchiole in the upper and middle lobes whereas, in the lower lobe, they run ventrally, and between the bronchioles. Finally they enter the left atrium as four large veins.     

The innervation and fine structure of paraneuronic cells in an amphibian pulmonary artery

Summary The pulmonary artery of Bufo marinus contains large numbers of bipolar cells situated in the tunica adventitia and in the outer layers of the media. These cells show a bright green-yellow fluorescence (emission spectra 485 nm) after formaldehyde pre-treatment suggesting that they contain a primary monoamine. The most characteristic fine-structural feature of these cells is the presence of numerous dense-cored vesicles (80—300 nm diameter) in their cytoplasm. The cells are in close contact (20 nm gap) with both agranular and granular nerve fibres. Both EM-cytochemical and formaldehyde-induced fluorescence tests indicate that the granule-containing nerve fibres are adrenergic. The agranular nerve fibres form discrete synaptic contacts with pre-and post-synaptic membrane thickenings on the cells. This was never observed with respect to the adrenergic fibres. Each process of the cells is about 45 m long. The processes do not bear any special relationship to either vessels of the arterial vasa vasorum or medial smooth muscle cells. Their location in the wall of the artery suggests that they are functionally significant with respect to activity of the arterial media.     

Increase in the growth inhibition of bovine pulmonary artery smooth muscle cells by an O-hexanoyl low-molecular-weight heparin derivative

Proliferation of pulmonary artery smooth muscle cells (PASMCs) appears to play a significant role in chronic pulmonary hypertension. The proliferation of PASMCs is strongly inhibited by some commercial heparin preparations. Heparin fragments were prepared by periodate treatment, followed by sodium borohydride reduction, to enhance potency. The tributylammonium salt of this fragmented heparin was O-acylated with hexanoic anhydride. Gradient polyacrylamide gel electrophoresis showed that the major heparin fragment contained eight disaccharide units. NMR analysis showed that approximately one hexanoyl group per disaccharide residue was present. The O-hexanoyl heparin fragments were assayed for growth inhibitory effect on bovine PASMCs in culture. This derivative was found to be more effective in growth inhibition of bovine PASMCs in culture than the heparin from which it was derived. In the future, it is envisioned that this or similar derivatives may be an effective treatment for pulmonary hypertension.     

鞍旁海绵状血管瘤的MRI诊断及误诊分析

目的:分析鞍旁海绵状血管瘤MR影像特点及误诊原因,提高对该疾病的诊断及鉴别诊断水平。方法:收集我院经手术病理证实的13例鞍旁海绵状血管瘤,术前均行MRI平扫及增强扫描,5例行3D-ASL检查,分析其影像学资料。结果:9例表现为横向哑铃状,鞍旁大,鞍内小,病灶主体位于颈内动脉外侧,颈内动脉海绵窦段被病灶包绕;1例鞍旁与鞍内病灶大小相似,1例病灶主体位于颈内动脉内侧,2例病灶完全位于颈内动脉外侧;7例垂体显示不清,6例垂体受推移;6例T2W I表现为类似脑脊液的极高信号;仅5例行3D-ASL检查,病灶均呈低灌注。误诊9例,其中4例误诊垂体腺瘤,5例误诊脑膜瘤。结论:横向哑铃状、病灶主体位于颈内动脉外侧及T2W I类似脑脊液的极高信号是鞍旁海绵状血管瘤的典型影像特征。对于不典型病变,借助3D-ASL可以减少误诊,充分掌握MRI影像特征及鉴别诊断的要点,对提高临床术前诊断水平具有重要价值。     

Earlier accumulation of calcium, phosphorus, and magnesium in the coronary artery in comparison with the ascending aorta, aortic valve, and mitral valve

To explore reasons for a high accumulation of Ca and P occurring in the coronary artery of Thai with aging, the authors investigated age-related changes of elements in the coronary artery, ascending aorta near the heart, and cardiac valves in single individuals, and the relationships in the elements between the coronary artery and either the ascending aorta or cardiac valves. After an ordinary dissection by medical students at Chiang Mai University was finished, the anterior descending arteries of the left coronary artery, ascending aortas, mitral valves, and aortic valves were resected from the subjects. The subjects consisted of 17 men and 9 women, ranging in age from 46 to 76 yr. The element content was analyzed by inductively coupled plasma-atomic emission spectrometry. The average content of Ca and P was the highest in the coronary artery and decreased in the order aortic valve, ascending aorta, and mitral valve. The Ca, P, and Mg content increased in the coronary artery in the fifties and in the ascending aorta, aortic valve, and mitral valve in the sixties. It should be noted that the accumulation of Ca, P, and Mg occurred earlier in the coronary artery than in the ascending aorta, aortic valve, and mitral valve. It was found that with respect to the Ca, P, Mg, and Na contents, the coronary artery correlated well with both the aortic valve and ascending aorta, especially with the aortic valve, but it did not correlate with the mitral valves. This finding suggests that the accumulation of Ca, P, Mg, and Na occurs in the coronary artery together with the aortic valve and ascending aorta, but not together with the mitral valve. Because regarding the accumulation of Ca, P, and Mg, the ascending aorta and aortic valve are preceded by the coronary artery, it is unlikely that the accumulation of Ca, P, and Mg spreads from the ascending aorta or aortic valve to the coronary artery.     

Magnetic resonance imaging based modeling of microvascular perfusion in patients with peripheral artery disease

Peripheral artery disease (PAD) is associated with an increased risk of adverse cardiovascular events, impaired lower extremity blood flow and microvascular perfusion abnormalities in the calf muscles which can be determined with contrast-enhanced magnetic resonance imaging (CE-MRI). We developed a computational model of the microvascular perfusion in the calf muscles. We included 20 patients (10 PAD, 10 controls) and utilized the geometry, mean signal intensity and arterial input functions from CE-MRI calf muscle perfusion scans. The model included the microvascular pressure (p_v), outflow filtration coefficient (OFC), transfer rate constant (k^t), porosity (φ), and the interstitial permeability (K_tissue). Parameters were fitted and the simulations were compared across PAD patients and controls. Intra-observer reproducibility of the simulated mean signal intensities was excellent (intraclass correlation coefficients >0.995). k^t and K_tissue were higher in PAD patients compared with controls (4.72 interquartile range (IQR) 3.33, 5.56 vs. 2.47 IQR 2.10, 2.85; p = 0.003; and 3.68 IQR 3.18, 4.41 vs. 1.81 IQR 1.81, 1.81; p < 0.001). Conversely, porosity (φ) was lower in PAD patients compared with controls (0.52 IQR 0.49, 0.54 vs. 0.61 IQR 0.58, 0.64; p = 0.016). Porosity (φ) was correlated with the ankle brachial index (r = 0.64, p = 0.011). The proposed computational microvascular model is robust and reproducible, and essential model parameters differ significantly between PAD patients and controls.     

磁共振成像对扩张型心肌病转基因模型小鼠左右心室对比分析

目的对cTnTR141W扩张型心肌病转基因模型小鼠左、右心室进行对比分析,研究cTnTR141W转基因小鼠作为右心室心肌病的动物模型的可行性。方法利用7.0 T高场强磁共振成像(MRI)技术,定量分析了2、4、6和8月龄对照组及cTnTR141W转基因模型小鼠左、右心室的舒张末容积(EDV)、收缩末容积(ESV)和射血分数(EF)的变化情况,同时对6月龄对照组cTnTR141W转基因模型小鼠心肌组织进行组织学分析。结果转基因阴性对照小鼠相比,cTnTR141W转基因小鼠左、右心室的容积在2月龄时已有增大趋势,而射血分数有减小趋势。右心室射血分数减小出现最早也最显著(P<0.05)。随年龄增加,cTnTR141W转基因小鼠与转基因阴性对照小鼠相比,右心室的结构和功能的病理生理变化与左心室同时趋于严重。该小鼠左、右心室在4月龄后表现典型的扩张型心肌病表型。结论 cTnTR141W转基因模型小鼠左心室和右心室的扩张性心肌病表型同时出现,该小鼠可作为右室性心肌病等右心室功能下降相关疾病研究的动物模型。     

Model-based cap thickness and peak cap stress prediction for carotid MRI

A rupture-prone carotid plaque can potentially be identified by calculating the peak cap stress (PCS). For these calculations, plaque geometry from MRI is often used. Unfortunately, MRI is hampered by a low resolution, leading to an overestimation of cap thickness and an underestimation of PCS. We developed a model to reconstruct the cap based on plaque geometry to better predict cap thickness and PCS.We used histological stained plaques from 34 patients. These plaques were segmented and served as the ground truth. Sections of these plaques contained 93 necrotic cores with a cap thickness <0.62 mm which were used to generate a geometry-based model. The histological data was used to simulate in vivo MRI images, which were manually delineated by three experienced MRI readers. Caps below the MRI resolution (n = 31) were (digitally removed and) reconstructed according to the geometry-based model. Cap thickness and PCS were determined for the ground truth, readers, and reconstructed geometries.Cap thickness was 0.07 mm for the ground truth, 0.23 mm for the readers, and 0.12 mm for the reconstructed geometries. The model predicts cap thickness significantly better than the readers. PCS was 464 kPa for the ground truth, 262 kPa for the readers and 384 kPa for the reconstructed geometries. The model did not predict the PCS significantly better than the readers.The geometry-based model provided a significant improvement for cap thickness estimation and can potentially help in rupture-risk prediction, solely based on cap thickness. Estimation of PCS estimation did not improve, probably due to the complex shape of the plaques.