@article{ReiterGenslerRitteretal.2012,
  author    = {Reiter, Theresa and Gensler, Daniel and Ritter, Oliver and Weiss, Ingo and Geistert, Wolfgang and Kaufmann, Ralf and Hoffmeister, Sabine and Friedrich, Michael T. and Wintzheimer, Stefan and D{\"u}ring, Markus and Nordbeck, Peter and Jakob, Peter M. and Ladd, Mark E. and Quick, Harald H. and Bauer, Wolfgang R.},
  title     = {Direct cooling of the catheter tip increases safety for CMR-guided electrophysiological procedures},
  series = {Journal of Cardiovascular Magnetic Resonance},
  volume    = {14},
  journal   = {Journal of Cardiovascular Magnetic Resonance},
  number    = {12},
  doi       = {10.1186/1532-429X-14-12},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134927},
  year      = {2012},
  abstract  = {Background: One of the safety concerns when performing electrophysiological (EP) procedures under magnetic resonance (MR) guidance is the risk of passive tissue heating due to the EP catheter being exposed to the radiofrequency (RF) field of the RF transmitting body coil. Ablation procedures that use catheters with irrigated tips are well established therapeutic options for the treatment of cardiac arrhythmias and when used in a modified mode might offer an additional system for suppressing passive catheter heating. Methods: A two-step approach was chosen. Firstly, tests on passive catheter heating were performed in a 1.5 T Avanto system (Siemens Healthcare Sector, Erlangen, Germany) using a ASTM Phantom in order to determine a possible maximum temperature rise. Secondly, a phantom was designed for simulation of the interface between blood and the vascular wall. The MR-RF induced temperature rise was simulated by catheter tip heating via a standard ablation generator. Power levels from 1 to 6 W were selected. Ablation duration was 120 s with no tip irrigation during the first 60 s and irrigation at rates from 2 ml/min to 35 ml/min for the remaining 60 s (Biotronik Qiona Pump, Berlin, Germany). The temperature was measured with fluoroscopic sensors (Luxtron, Santa Barbara, CA, USA) at a distance of 0 mm, 2 mm, 4 mm, and 6 mm from the catheter tip. Results: A maximum temperature rise of 22.4 degrees C at the catheter tip was documented in the MR scanner. This temperature rise is equivalent to the heating effect of an ablator's power output of 6 W at a contact force of the weight of 90 g (0.883 N). The catheter tip irrigation was able to limit the temperature rise to less than 2 degrees C for the majority of examined power levels, and for all examined power levels the residual temperature rise was less than 8 degrees C. Conclusion: Up to a maximum of 22.4 degrees C, the temperature rise at the tissue surface can be entirely suppressed by using the catheter's own irrigation system. The irrigated tip system can be used to increase MR safety of EP catheters by suppressing the effects of unwanted passive catheter heating due to RF exposure from the MR scanner.},
  language  = {en}
}
@article{ReiterRitterPrinceetal.2012,
  author    = {Reiter, Theresa and Ritter, Oliver and Prince, Martin R. and Nordbeck, Peter and Wanner, Christoph and Nagel, Eike and Bauer, Wolfgang R.},
  title     = {Minimizing Risk of Nephrogenic systemic fibrosis in Cardiovascular Magnetic Resonance},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75068},
  year      = {2012},
  abstract  = {Nephrogenic Systemic Fibrosis is a rare condition appearing only in patients with severe renal impairment or failure and presents with dermal lesions and involvement of internal organs. Although many cases are mild, an estimated 5 \% have a progressive debilitating course. To date, there is no known effective treatment thus stressing the necessity of ample prevention measures. An association with the use of Gadolinium based contrast agents (GBCA) makes Nephrogenic Systemic Fibrosis a potential side effect of contrast enhanced magnetic resonance imaging and offers the opportunity for prevention by limiting use of gadolinium based contrast agents in renal failure patients. In itself toxic, Gadolinium is embedded into chelates that allow its safe use as a contrast agent. One NSF theory is that Gadolinium chelates distribute into the extracellular fluid compartment and set Gadolinium ions free, depending on multiple factors among which the duration of chelates exposure is directly related to the renal function. Major medical societies both in Europe and in North America have developed guidelines for the usage of GBCA. Since the establishment of these guidelines and the increased general awareness of this condition, the occurrence of NSF has been nearly eliminated. Giving an overview over the current knowledge of NSF pathobiochemistry, pathogenesis and treatment options this review focuses on the guidelines of the European Medicines Agency, the European Society of Urogenital Radiology, the FDA and the American College of Radiology from 2008 up to 2011 and the transfer of this knowledge into every day practice.},
  subject      = {CMR},
  language  = {en}
}
@article{ReiterRitterNordbecketal.2012,
  author    = {Reiter, Theresa and Ritter, Oliver and Nordbeck, Peter and Beer, Meinrad and Bauer, Wolfgang Rudolf},
  title     = {MRI-guided ablation of wide complex tachycardia in a univentricular heart},
  series = {World Journal of Cardiology},
  volume    = {4},
  journal   = {World Journal of Cardiology},
  number    = {8},
  doi       = {10.4330/wjc.v4.i8.260},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123165},
  pages     = {260-263},
  year      = {2012},
  abstract  = {Magnetic resonance imaging can be used for preprocedural assessment of complex anatomy for radiofrequency (RF) ablations, e.g., in a univentricular heart. This case report features the treatment of a young patient with a functionally univentricular heart who suffered from persistent sudden onset tachycardia with wide complexes that required RF ablation as treatment.},
  language  = {en}
}
@article{NordbeckBeerKoestleretal.2012,
  author    = {Nordbeck, Peter and Beer, Meinrad and K{\"o}stler, Herbert and Ladd, Mark E. and Quick, Harald H. and Bauer, Wolfgang R. and Ritter, Oliver},
  title     = {Cardiac catheter ablation under real-time magnetic resonance guidance},
  series = {European Heart Journal},
  volume    = {33},
  journal   = {European Heart Journal},
  number    = {15},
  doi       = {10.1093/eurheartj/ehs139},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125638},
  year      = {2012},
  abstract  = {One of the main shortcomings of interventional electrophysiology (EP) is its inability to generate sufficient soft tissue contrast for intra-procedural visualization of the myocardium and the surrounding tissue, using conventional imaging techniques. Interventional cardiovascular magnetic resonance imaging (MRI) aims at bringing about significant improvements to the complex and decisive EP interventions far beyond the capabilities of currently available supportive imaging techniques used to surmount the drawbacks of fluoroscopy, as MRI not only allows of precise three-dimensional exposure of the cardiovascular morphology, but also proves to be a promising technique exclusively suitable for direct visualization of arrhythmogenic substrate and therapeutic effects. The major challenge posed by clinical …},
  language  = {en}
}
@article{BloemerPachelHofmannetal.2013,
  author    = {Bl{\"o}mer, Nadja and Pachel, Christina and Hofmann, Urlich and Nordbeck, Peter and Bauer, Wolfgang and Mathes, Denise and Frey, Anna and Bayer, Barbara and Vogel, Benjamin and Ertl, Georg},
  title     = {5-Lipoxygenase facilitates healing after myocardial infarction},
  series = {Basic Research in Cardiology},
  volume    = {108},
  journal   = {Basic Research in Cardiology},
  number    = {4},
  doi       = {10.1007/s00395-013-0367-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132602},
  year      = {2013},
  abstract  = {Early healing after myocardial infarction (MI) is characterized by a strong inflammatory reaction. Most leukotrienes are pro-inflammatory and are therefore potential mediators of healing and remodeling after myocardial ischemia. The enzyme 5-lipoxygenase (5-LOX) has a key role in the transformation of arachidonic acid in leukotrienes. Thus, we tested the effect of 5-LOX on healing after MI. After chronic coronary artery ligation, early mortality was significantly increased in 5-LOX\(^{-/-}\) when compared to matching wildtype (WT) mice due to left ventricular rupture. This effect could be reproduced in mice treated with the 5-LOX inhibitor Zileuton. A perfusion mismatch due to the vasoactive potential of leukotrienes is not responsible for left ventricular rupture since local blood flow assessed by magnetic resonance perfusion measurements was not different. However, after MI, there was an accentuation of the inflammatory reaction with an increase of pro-inflammatory macrophages. Yet, mortality was not changed in chimeric mice (WT vs. 5-LOX\(^{-/-}\) bone marrow in 5-LOX\(^{-/-}\) animals), indicating that an altered function of 5-LOX\(^{-/-}\) inflammatory cells is not responsible for the phenotype. Collagen production and accumulation of fibroblasts were significantly reduced in 5-LOX\(^{-/-}\) mice in vivo after MI. This might be due to an impaired migration of 5-LOX\(^{-/-}\) fibroblasts, as shown in vitro to serum. In conclusion, a lack or inhibition of 5-LOX increases mortality after MI because of healing defects. This is not mediated by a change in local blood flow, but through an altered inflammation and/or fibroblast function.},
  language  = {en}
}
@article{NordbeckBoenhofHilleretal.2013,
  author    = {Nordbeck, Peter and B{\"o}nhof, Leoni and Hiller, Karl-Heinz and Voll, Sabine and Arias-Loza, Paula and Seidlmaier, Lea and Williams, Tatjana and Ye, Yu-Xiang and Gensler, Daniel and Pelzer, Theo and Ertl, Georg and Jakob, Peter M. and Bauer, Wolfgang R. and Ritter, Oliver},
  title     = {Impact of Thoracic Surgery on Cardiac Morphology and Function in Small Animal Models of Heart Disease: A Cardiac MRI Study in Rats},
  series = {PLoS ONE},
  volume    = {8},
  journal   = {PLoS ONE},
  number    = {8},
  doi       = {10.1371/journal.pone.0068275},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130064},
  pages     = {e68275},
  year      = {2013},
  abstract  = {Background Surgical procedures in small animal models of heart disease might evoke alterations in cardiac morphology and function. The aim of this study was to reveal and quantify such potential artificial early or long term effects in vivo, which might account for a significant bias in basic cardiovascular research, and, therefore, could potentially question the meaning of respective studies. Methods Female Wistar rats (n = 6 per group) were matched for weight and assorted for sham left coronary artery ligation or control. Cardiac morphology and function was then investigated in vivo by cine magnetic resonance imaging at 7 Tesla 1 and 8 weeks after the surgical procedure. The time course of metabolic and inflammatory blood parameters was determined in addition. Results Compared to healthy controls, rats after sham surgery showed a lower body weight both 1 week (267.5±10.6 vs. 317.0±11.3 g, n<0.05) and 8 weeks (317.0±21.1 vs. 358.7±22.4 g, n<0.05) after the intervention. Left and right ventricular morphology and function were not different in absolute measures in both groups 1 week after surgery. However, there was a confined difference in several cardiac parameters normalized to the body weight (bw), such as myocardial mass (2.19±0.30/0.83±0.13 vs. 1.85±0.22/0.70±0.07 mg left/right per g bw, p<0.05), or enddiastolic ventricular volume (1.31±0.36/1.21±0.31 vs. 1.14±0.20/1.07±0.17 µl left/right per g bw, p<0.05). Vice versa, after 8 weeks, cardiac masses, volumes, and output showed a trend for lower values in sham operated rats compared to controls in absolute measures (782.2±57.2/260.2±33.2 vs. 805.9±84.8/310.4±48.5 mg, p<0.05 for left/right ventricular mass), but not normalized to body weight. Matching these findings, blood testing revealed only minor inflammatory but prolonged metabolic changes after surgery not related to cardiac disease. Conclusion Cardio-thoracic surgical procedures in experimental myocardial infarction cause distinct alterations upon the global integrity of the organism, which in the long term also induce circumscribed repercussions on cardiac morphology and function. This impact has to be considered when analyzing data from respective animal studies and transferring these findings to conditions in patients.},
  language  = {en}
}
@article{GotschyBauerWinteretal.2017,
  author    = {Gotschy, Alexander and Bauer, Wolfgang R. and Winter, Patrick and Nordbeck, Peter and Rommel, Eberhard and Jakob, Peter M. and Herold, Volker},
  title     = {Local versus global aortic pulse wave velocity in early atherosclerosis: An animal study in ApoE\(^{-/-}\) mice using ultrahigh field MRI},
  series = {PLoS ONE},
  volume    = {12},
  journal   = {PLoS ONE},
  number    = {2},
  doi       = {10.1371/journal.pone.0171603},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171824},
  year      = {2017},
  abstract  = {Increased aortic stiffness is known to be associated with atherosclerosis and has a predictive value for cardiovascular events. This study aims to investigate the local distribution of early arterial stiffening due to initial atherosclerotic lesions. Therefore, global and local pulse wave velocity (PWV) were measured in ApoE\(^{-/-}\) and wild type (WT) mice using ultrahigh field MRI. For quantification of global aortic stiffness, a new multi-point transit-time (TT) method was implemented and validated to determine the global PWV in the murine aorta. Local aortic stiffness was measured by assessing the local PWV in the upper abdominal aorta, using the flow/area (QA) method. Significant differences between age matched ApoE\(^{-/-}\) and WT mice were determined for global and local PWV measurements (global PWV: ApoE\(^{-/-}\): 2.7 ±0.2m/s vs WT: 2.1±0.2m/s, P<0.03; local PWV: ApoE\(^{-/-}\): 2.9±0.2m/s vs WT: 2.2±0.2m/s, P<0.03). Within the WT mouse group, the global PWV correlated well with the local PWV in the upper abdominal aorta (R\(^2\) = 0.75, P<0.01), implying a widely uniform arterial elasticity. In ApoE\(^{-/-}\) animals, however, no significant correlation between individual local and global PWV was present (R\(^2\) = 0.07, P = 0.53), implying a heterogeneous distribution of vascular stiffening in early atherosclerosis. The assessment of global PWV using the new multi-point TT measurement technique was validated against a pressure wire measurement in a vessel phantom and showed excellent agreement. The experimental results demonstrate that vascular stiffening caused by early atherosclerosis is unequally distributed over the length of large vessels. This finding implies that assessing heterogeneity of arterial stiffness by multiple local measurements of PWV might be more sensitive than global PWV to identify early atherosclerotic lesions.},
  language  = {en}
}