Abnormal Haemodynamic Flow Patterns in Bicuspid Pulmonary Valve Disease

Abnormal flow patterns in the aortas of those with bicuspid aortic valves (BAVs) are increasingly recognized as important in the pathogenesis of aortic dilatation but pulmonary flow patterns in bicuspid pulmonary valves have not been studied. Bicuspid pulmonary valve disease is rare and a small numbers of case reports describe concomitant pulmonary artery dilation similar to the dilation of the ascending aorta, which is often seen in BAVs disease. We examined three cases of bicuspid pulmonary valve disease, 10 healthy volunteers and 10 patients with BAV disease but a tricuspid pulmonary valve. All participants underwent anatomical and functional imaging of the pulmonary valve, pulmonary artery, and right ventricle as well as advanced time-resolved 3-dimensional cardiac magnetic resonance imaging (4D flow) to assess the flow pattern in the pulmonary artery. All patients with a bicuspid pulmonary valve had pulmonary artery dilation and showed distinct helical flow abnormalities with increased rotational flow and increased flow displacement compared to a mild left-handed flow pattern in the healthy volunteers. Additionally, there was marked asymmetry seen in the systolic wall shear stress (WSS) pattern, with the highest values in the anterior wall of the pulmonary artery. In comparison, patients with a BAV but a tricuspid pulmonary valve had normal flow patterns in the pulmonary artery. These haemodynamic findings are similar to recent studies in bicuspid aortic disease, and suggest the importance of flow patterns in the pathophysiology of vessel dilation in both aortic and pulmonary bicuspid valve disease

Screening for proximal coronary artery anomalies with 3-dimensional MR coronary angiography

Under 35 years of age, 14% of sudden cardiac death in athletes is caused by a coronary artery anomaly (CAA). Free-breathing 3-dimensional magnetic resonance coronary angiography (3D-MRCA) has the potential to screen for CAA in athletes and non-athletes as an addition to a clinical cardiac MRI protocol. A 360 healthy men and women (207 athletes and 153 non-athletes) aged 18–60 years (mean age 31 ± 11 years, 37% women) underwent standard cardiac MRI with an additional 3D-MRCA within a maximum of 10 min scan time. The 3D-MRCA was screened for CAA. A 335 (93%) subjects had a technically satisfactory 3D-MRCA of which 4 (1%) showed a malignant variant of the right coronary artery (RCA) origin running between the aorta and the pulmonary trunk. Additional findings included three subjects with ventral rotation of the RCA with kinking and possible proximal stenosis, one person with additional stenosis and six persons with proximal myocardial bridging of the left anterior descending coronary artery. Coronary CT-angiography (CTA) was offered to persons with CAA (the CAA was confirmed in three, while one person declined CTA) and stenosis (the ventral rotation of the RCA was confirmed in two but without stenosis, while two people declined CTA). Overall 3D MRCA quality was better in athletes due to lower heart rates resulting in longer end-diastolic resting periods. This also enabled faster scan sequences. A 3D-MRCA can be used as part of the standard cardiac MRI protocol to screen young competitive athletes and non-athletes for anomalous proximal coronary arteries

Atherosclerotic pattern of coronary myocardial bridging assessed with CT coronary angiography

The aim of our study was to evaluate the atherosclerotic pattern of patients with coronary myocardial bridging (MB) by means of CT Coronary Angiography (CT-CA). 254 consecutive patients (166 male, mean age 58.6 ± 10.3) who underwent 64-slice CT-CA according to current clinical indications were reviewed for the presence of MB and concomitant segmental atherosclerotic pattern. Coronary plaques were assessed in all patients enrolled. 73 patients (29%) presented single (90%) or multiple (10%) MB, frequently (93%) localized in the mid-distal left anterior descending artery. The MB segment was always free of atherosclerosis. Segments proximal to the MB presented: no atherosclerotic disease (n = 37), positive remodeling (n = 23), 50% stenoses (n = 7). Distal segments presented a different atherosclerosis pattern (P < 0.0001): absence of disease (n = 73), no significant lesions (n = 8). No significant differences were found between segments proximal to MB and proximal coronary segments apart from left main trunk. Pattern of atherosclerotic lesions located in segments 6 and 7 significantly differs between patients with MB and patients without MB (P < 0.05). CT-CA is a reliable method to non-invasively demonstrate MB and related atherosclerotic pattern. CT-CA provides new insight regarding atherosclerosis distribution in segments close to MB

Perylene and its diimides : investigation of the influence of molecular diffusion on the thin film growth

Highly ordered organic thin films are required to realize novel electronics and optical applications for high-performance devices based on the class of organic materials. In this context, the present work focuses on the understanding of the processes involved in thin film growth. The aim is to control and optimize the formation of organic thin films. Thus, successful growth strategies are developed. The nucleation and growth of organic thin films is mainly examined with Atomic Force Microscopy (AFM). X-Ray Diffraction (XRD) methods are used to explore the crystalline structure.One way to improve the efficiency of devices with organic thin films as active layer, is to control the film growth by the application of dielectric surface modifications (DSMs). The energetics of the substrate surface are tailored by means of such organic molecules forming self-assembling monolayers (SAMs) or polymeric dielectrics. Often, the DSMs are chosen according to their tendency to change the surface free energy (SFE). Other parameters of the DSMs, affecting the morphology of the film on top, are not yet completely identified and understood. This insufficient comprehension hinders an elaborate choice of modifications. In the current thesis, the DSMs are chosen in a way that the SFE of the modified silicon substrates is analogously lowered. This offers the opportunity to precisely investigate the influence of parameters such as the morphology and roughness of the modified surface or a dipole at the interface, on the subsequent film growth. From previous growth studies it is known that lowering the surface free energy usually causes an enhancement of the molecular diffusivity on top of these surfaces. In addition, a high diffusivity is known to be correlated to the growth of large and well ordered islands, which results in good working devices. In this thesis, three different DSMs are investigated. On a polymeric modification with a homogeneous surface, highly ordered films are grown. On rough and irregular surfaces of another DSM, a certain diminution of the diffusion length of organic small molecules is clearly observed. Moreover, it is clearly shown, that the application of the investigated highly electronegative SAM inhibits an increase of the molecular diffusivity despite its low SFE. The interface dipole reduces the diffusion length of molecules. In addition to the investigation of surface modifications, an aim of this work is to understand the growth behavior of different small organic molecules. Therefore, perylene and some of its diimides are studied. The influence of the alkyl chain length of the N,N’-dialkyl perylene tetracarboxylic diimides (PTCDIs) is analyzed. For the different films formed, corresponding growth models are established. Perylene results as a reference system for 3-dimensional growth, also known as island growth. The diimides with the longest alkyl chain, PTCDI-C13, is a reference for highly 2-dimensional growth, which corresponds to layer-by-layer growth. It can be shown that for the PTCDIs, which are examined in this study, the alkyl chain length correlates with the growth type. The PTCDIs with long alkyl chains exhibit a clear layer-by-layer growth behavior with high structural order of the films, whereas, shorter molecules preferably grow 3-dimensionally. Increasing the substrate temperature during film deposition results in the increase in structural order within the thin films. Thus, the production of films with extremely high internal ordering has been successful