Titus Kuehne

Berlin Heart, Berlín, Berlin, Germany

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Publications (114)475.91 Total impact

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    ABSTRACT: The coarctation of the aorta (CoA), a local narrowing of the aortic arch, accounts for 7 % of all congenital heart defects. Stenting is a recommended therapy to reduce the pressure gradient. This procedure is associated with complications such as the development of adverse flow conditions. A computer-aided treatment planning based on flow simulations can help to predict possible complications. The virtual stent planning is an important, intermediate step in the treatment planning pipeline. We present a novel approach that automatically suggests a stent setup and provides a set of intuitive parameters that allow for an interactive adaption of the suggested stent placement and induced deformation. A high-quality mesh and a centerline are automatically generated. The stent-induced deformation is realized through a deformation of the centerline and a vertex displacement with respect to the deformed centerline and additional stent parameters. The parameterization is automatically derived from the underlying data and can be optionally altered through a condensed set of clinically sound parameters. The automatic deformation can be generated in about 25 s on a consumer system. The interactive adaption can be performed in real time. Compared with manual expert reconstructions of the stented vessel section, the mean difference of vessel path and diameter is below 1 mm. Our approach enables a medical user to easily generate a plausibly deformed vessel mesh which is necessary as input for a simulation-based treatment planning of CoA.
    International Journal of Computer Assisted Radiology and Surgery 05/2015; DOI:10.1007/s11548-015-1220-3 · 1.66 Impact Factor
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    ABSTRACT: Background Beta-blockers contribute to treatment of heart failure. Their mechanism of action, however, is incompletely understood. Gradients in beta-blocker sensitivity of helically aligned cardiomyocytes as compared to counteracting transversely intruding cardiomyocytes seem crucial. We hypothesize that selective blockade of transversely intruding cardiomyocytes by low-dose beta-blockade unloads ventricular performance. Cardiac magnetic resonance imaging (MRI) 3D-tagging delivers parameters of myocardial performance. Methods and Results We studied 13 healthy volunteers by MRI 3D-tagging during escalated i.v.-administration of Esmolol. The circumferential, longitudinal and radial myocardial shortening was determined for each dose. The curves were analysed for peak value, time-to-peak, upslope, and area-under-the-curve. At low doses, from 5 to 25 μg/kg/min, peak contraction increased while time-to-peak decreased yielding a steeper upslope. Combining the values revealed a left shift of the curves at low doses when compared to baseline without Esmolol. At doses of 50 to 150 μg/kg/min, a right shift with flattening occurred. Conclusions In healthy volunteers we found more pronounced myocardial shortening at low compared to clinical dosage of beta-blockers. In patients with ventricular hypertrophy and higher prevalence of transversely intruding cardiomyocytes selective low-dose beta-blockade could be even more effective. MRI 3D-tagging could help to determine optimal individual beta-blocker dosing avoiding undesirable side effects. Copyright © 2014, American Journal of Physiology - Heart and Circulatory Physiology.
    AJP Heart and Circulatory Physiology 04/2015; DOI:10.1152/ajpheart.00746.2014 · 4.01 Impact Factor
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    ABSTRACT: Background The role of intracardiac blood flow behavior within the context of manifestation and interventional success in patients with mitral regurgitation is unknown to date. The present study aims to assess left ventricular blood flow behavior characterized by kinetic energy (KE) in patients with mitral regurgitation before and after mitral valve surgery.Methods Patients with mitral regurgitation (mean age 56 ± 9 years) and the necessity for mitral valve repair (n = 6) or biological valve replacement (n = 4) received cardiac magnetic resonance before and after surgery and were compared with a group of healthy volunteers (n = 7; mean age 27 ± 7 years). Volumetric data and KE of the left ventricle were obtained for all subjects. KE normalized and nonnormalized to volume was calculated from four-dimensional flow magnetic resonance imaging. Mean KE and KE peaks (systolic, early-diastolic and late diastolic), and end-systolic phase duration were considered.ResultsEnd-diastolic, end-systolic and stroke volume were significantly higher in patients with mitral regurgitation than in healthy volunteers (P = 0.00, 0.01, and 0.00, respectively) and decreased significantly after surgery (P = 0.00, 0.01, and 0.00, respectively). A significant postoperative decrease of mean KE, systolic and early-diastolic KE peaks was observed (P = 0.01, 0.02, and 0.01, respectively). Late-diastolic KE peak remained high in postoperative patients (P = 0.58).Conclusion Intracardiac blood flow as characterized by measurements of KE is altered in patients with mitral regurgitation. Physiological flow conditions appear to not fully be restored with mitral valve surgery. J. Magn. Reson. Imaging 2015.
    Journal of Magnetic Resonance Imaging 04/2015; DOI:10.1002/jmri.24926 · 2.79 Impact Factor
  • Journal of the American College of Cardiology 03/2015; 65(10):A1292. DOI:10.1016/S0735-1097(15)61292-X · 15.34 Impact Factor
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    ABSTRACT: In patients with CHD, cardiac MRI is often indicated for functional and anatomical assessment. With the recent introduction of MRI-conditional pacemaker systems, cardiac MRI has become accessible for patients with pacemakers. The present clinical study aims to evaluate safety, susceptibility artefacts, and image reading of cardiac MRI in patients with CHD and MRI-conditional pacemaker systems. Material and methods CHD patients with MRI-conditional pacemaker systems and a clinical need for cardiac MRI were examined with a 1.5-T MRI system. Lead function was tested before and after MRI. Artefacts and image readings were evaluated using a four-point grading scale. A total of nine patients with CHD (mean age 34.0 years, range 19.5-53.6 years) received a total of 11 cardiac MRI examinations. Owing to clinical indications, seven patients had previously been converted from conventional to MRI-conditional pacemaker systems. All MRI examinations were completed without adverse effects. Device testing immediately after MRI and at follow-up showed no alteration of pacemaker device and lead function. Clinical questions could be addressed and answered in all patients. Cardiac MRI can be performed safely with high certainty of diagnosis in CHD patients with MRI-conditional pacemaker systems. In case of clinically indicated lead and box changing, CHD patients with non-MRI-conditional pacemaker systems should be considered for complete conversion to MRI-conditional systems.
    Cardiology in the Young 02/2015; DOI:10.1017/S1047951115000190 · 0.86 Impact Factor
  • American Heart Association, Chicago , IL 2014; 11/2014
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    ABSTRACT: Current models for real time study of the effects of myocardial ischemia/reperfusion have major limitations and confounders. Confounders include the surgical stresses of a thoracotomy and abnormal physiology of an open chest. The need to reposition the animal interferes with the study of the early changes associated with ischemia. Direct comparison of pre-ischemia and post-ischemia images is then difficult. We developed a novel “closed chest” model of ischemia/reperfusion to overcome these issues. Following thoracotomy, we sutured a balloon occluder to the left coronary artery of male Sprague–Dawley rats. We used both visual inspection and ECG to assess for successful occlusion and reperfusion of the coronary artery at the time of operation by brief inflation and deflation of the balloon. The tubing was then placed under the skin and the incision closed. Following a recovery period (5–10 days), the animals underwent MRI. We performed baseline assessment of left ventricle function, and repeated LV measurement during a 15-min coronary occlusion and again during a 60-min reperfusion period following reopening of the coronary artery. The occluder was successfully placed in 40 of 44 animals. Four developed intraoperative complications; two large myocardial infarction, two terminal bleeding. Six died in the week following surgery, [four sudden deaths (presumed arrhythmic), one anterior infarction, one sepsis]. Cine-MRI demonstrated localised hypokinesia in 31 of the remaining 34 animals. LV ejection fraction (EF) was reduced from 63 ± 7 % at baseline, to 49 ± 9 % during coronary occlusion. LV EF recovered to 61 ± 2 %. The area at risk on staining of the heart was 41.9 ± 15.8 %. This method allows the effects of ischemia/reperfusion to be studied before, during, and after coronary occlusion. Ischemia can be caused while the animal is in the MRI. This new and clinically relevant small animal model is a valuable tool to study the effects of single or repeated coronary occlusion/reperfusion in real-time.
    The International Journal of Cardiovascular Imaging 10/2014; 31(1). DOI:10.1007/s10554-014-0539-0 · 2.32 Impact Factor
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    ABSTRACT: Pressure drop associated with coarctation of the aorta (CoA) can be successfully treated surgically or by stent placement. However, a decreased life expectancy associated with altered aortic hemodynamics was found in long-term studies. Image-based computational fluid dynamics (CFD) is intended to support particular diagnoses, to help in choosing between treatment options, and to improve performance of treatment procedures. This study aimed to prove the ability of CFD to improve aortic hemodynamics in CoA patients. In 13 patients (6 males, 7 females; mean age 25 ± 14 years), we compared pre- and post-treatment peak systole hemodynamics [pressure drops and wall shear stress (WSS)] vs. virtual treatment as proposed by biomedical engineers. Anatomy and flow data for CFD were based on MRI and angiography. Segmentation, geometry reconstruction and virtual treatment geometry were performed using the software ZIBAmira, whereas peak systole flow conditions were simulated with the software ANSYS(®) Fluent(®). Virtual treatment significantly reduced pressure drop compared to post-treatment values by a mean of 2.8 ± 3.15 mmHg, which significantly reduced mean WSS by 3.8 Pa. Thus, CFD has the potential to improve post-treatment hemodynamics associated with poor long-term prognosis of patients with coarctation of the aorta. MRI-based CFD has a huge potential to allow the slight reduction of post-treatment pressure drop, which causes significant improvement (reduction) of the WSS at the stenosis segment.
    Annals of Biomedical Engineering 09/2014; 43(1). DOI:10.1007/s10439-014-1116-3 · 3.23 Impact Factor
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    ABSTRACT: This study compared pressure fields by 4-dimensional (4D), velocity-encoded cine (VEC) cardiac magnetic resonance imaging (CMR) with pressures measured by the clinical gold standard catheterization. Thirteen patients (n = 7 male, n = 6 female) with coarctation were studied. The 4D-VEC-CMR pressure fields were computed by solving the Pressure-Poisson equation. The agreement between catheterization and CMR-based methods was determined at 5 different measurement sites along the aorta. For all sites, the correlation coefficients between measures varied between 0.86 and 0.97 (p < 0.001). The Bland-Altman test showed good agreement between peak systolic pressure gradients across the coarctation. The nonsignificant (p > 0.2) bias was +2.3 mm Hg (± 6.4 mm Hg, 2 SDs) for calibration with dynamic pressures and +1.5 mm Hg (± 4.6 mm Hg, 2 SDs) for calibration with static pressure. In a clinical setting of coarctation, pressure fields can be accurately computed from 4D-VEC-CMR–derived flows. In patients with coarctation, this noninvasive technique might evolve to an alternative to invasive catheterization.
    JACC Cardiovascular Imaging 09/2014; 7(9):920–926. DOI:10.1016/j.jcmg.2014.03.017 · 6.99 Impact Factor
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    05/2014; 15(suppl 1):i1-i7. DOI:10.1093/ehjci/jeu083
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    ABSTRACT: PurposeTo reduce the need for diagnostic catheterization and optimize treatment in a variety of congenital heart diseases, magnetic resonance imaging (MRI)-based computational fluid dynamics (CFD) is proposed. However, data about the accuracy of CFD in a clinical context are still sparse. To fill this gap, this study compares MRI-based CFD to catheterization in the coarctation of aorta (CoA) setting.Materials and Methods Thirteen patients with CoA were investigated by routine MRI prior to catheterization. 3D whole-heart MRI was used to reconstruct geometries and 4D flow-sensitive phase-contrast MRI was used to acquire flows. Peak systolic flows were simulated using the program FLUENT.ResultsPeak systolic pressure drops in CoA measured by catheterization and CFD correlated significantly for both pre- and posttreatment measurements (pre: r = 0.98, p = 0.00; post: r = 0.87, p = 0.00). The pretreatment bias was −0.5 ± 3.33 mmHg (95% confidence interval −2.55 to 1.47 mmHg). CFD predicted a reduction of the peak systolic pressure drop after treatment that ranged from 17.6 ± 5.56 mmHg to 6.7 ± 5.58 mmHg. The posttreatment bias was 3.0 ± 2.91 mmHg (95% CI −1.74 to 5.43 mmHg).Conclusion Peak systolic pressure drops can be reliably calculated using MRI-based CFD in a clinical setting. Therefore, CFD might be an attractive noninvasive alternative to diagnostic catheterization.J. Magn. Reson. Imaging 2014. © 2014 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 04/2014; 41(4). DOI:10.1002/jmri.24639 · 2.79 Impact Factor
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    ABSTRACT: Strongly evolving imaging technologies such as magnetic resonance imaging (MRI) nowadays provide a multitude of new complementary techniques for the analysis of cardiovascular tissue properties, function, and hemodynamics. The purpose of the presented work is to provide a research tool, which enables a quick validation of newly developed imaging techniques and supports the co-development of clinically usable analysis tools, which allow an integration with existing complementary examination methods. The concepts combined to this end consist of an integration with the open source research PACS OsiriX, an advanced heuristic DICOM classification and preprocessing as well as an integrative data model, which accumulates patient-specific image data, results and the data relations. Specific processing and analysis plugins can easily be integrated in such a way that they use the data integration and visualization infrastructure as well as results from other existing plugins. The presented example applications, such as the evaluation of slice orientations for cardiac function quantification or the integrated analysis of different types of image data for diagnosis of myocarditis show that the provided tool can be successfully used for a multitude of research applications in cardiovascular imaging.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2014; DOI:10.1117/12.2043735 · 0.20 Impact Factor
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    ABSTRACT: A unique feature of cardiac magnetic resonance is its ability to characterize myocardium. Proton relaxation times, T1, T2, and T2* are a reflection of the composition of individual tissues, and change in the presence of disease. Research into T1 mapping has largely been focused in the study of cardiomyopathies, but T1 mapping also shows huge potential in the study of ischaemic heart disease. In fact, the first cardiac T1 maps were used to characterize myocardial infarction. Robust high-resolution myocardial T1 mapping is now available for use as a clinical tool. This quantitative technique is simple to perform and analyse, minimally subjective, and highly reproducible. This review aims to summarize the present state of research on the topic, and to show the clinical potential of this method to aid the diagnosis and treatment of patients with ischaemic heart disease.
    02/2014; 15(6). DOI:10.1093/ehjci/jeu024
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    ABSTRACT: Double aortic arch is a rare congenital anomaly. It is usually diagnosed and surgically corrected at an early age due to symptoms as dyspnea and dysphagia caused by an obstruction of trachea and/or esophagus in the vascular ring. We present the case of an asymptomatic 14-year-old patient with complete double aortic arch as demonstrated by CMR. Blood flow in the right and left aortic arch was visualized and quantified by 4D-flow MRI.
    02/2014; 4(1):44-6. DOI:10.3978/j.issn.2223-3652.2014.02.04
  • Journal of Cardiovascular Magnetic Resonance 01/2014; 16(Suppl 1):P16-P16. DOI:10.1186/1532-429X-16-S1-P16 · 5.11 Impact Factor
  • Journal of Cardiovascular Magnetic Resonance 01/2014; 16(Suppl 1):P282. DOI:10.1186/1532-429X-16-S1-P282 · 5.11 Impact Factor
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    ABSTRACT: We aimed to investigate the histological and clinical presentations of EAM induced by different immunization schemes. Male young Lewis rats were divided into 5 groups immunized by porcine myocardial myosin: subcutaneously (SC) 1 2 mg (in two 1 mg doses on day 0 and 7); 0 mg (sham group) subcutaneously into rear footpads (RF), 0.25 mg RF, 0.5 mg RF or 1 mg RF (all RF once on day 0). On day 21 left ventricular (LV) function was assessed by cardiac magnetic resonance imaging and cardiac catheterization. The type and degree of myocardial inflammatory infiltrates were determined by conventional histology and immunohistochemistry. In the SC immunized rats and in the RF sham group we observed 0% mortality, while in the actively RF immunized rats mortality was 20%, 20% and 44% for the 0.25 mg, 0.5 mg and 1 mg myosin doses respectively. Morbidity as defined by inflammatory infiltrates on HE staining was 22% in the SC immunized rats, 0% in the RF sham group and 100% in all actively RF immunized groups. We observed augmented relative ventricle weight and spleen weight, increased LV end-diastolic pressure, reduced LV developed pressure and reduced LV ejection fraction in all with myosin immunized RF groups without any systematic dose effect. Subcutaneous immunization to the neck and flanks did not induce a reproducible EAM, while RF myosin administration reliably led to EAM. Lower myosin doses seem to induce the complete histological and clinical picture of EAM while being associated with lower mortality, non-specific symptoms and animal distress. This article is protected by copyright. All rights reserved.
    Acta Physiologica 01/2014; 210(4). DOI:10.1111/apha.12227 · 4.25 Impact Factor
  • The Thoracic and Cardiovascular Surgeon 10/2013; 61(S 02). DOI:10.1055/s-0033-1354498 · 1.08 Impact Factor
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    ABSTRACT: -In repaired congenital heart disease, there is increasing evidence of gender differences in cardiac remodelling, but there is a lack of comparable data for specific congenital heart defects, such as in repaired tetralogy of Fallot (r-ToF). -In a prospective multicentre study, a cohort of 272 contemporary patients (158 male, mean age 14.3± 3.3, range 8-20 years) with r-ToF underwent cardiac magnetic resonance for ventricular function and metabolic exercise testing. All data were transformed to standard deviation scores (SDS) according to the Lambda-Mu-Sigma method by relating individual values to their respective 50(th) percentile (SDS=0) in sex-specific healthy controls. No gender differences were observed in age at repair, the type of repair conducted or in overall hemodynamic results. Relative to sex-specific controls, female r-ToF patients had larger right ventricular (RV) end-systolic volumes (SDS females +4.35, males +3.25, p=0.001), lower RV ejection fraction (females -2.83, males -2.12, p=0.011), lower RV muscle mass (females +1.58, males +2.45, p=0.001), poorer peak oxygen uptake (females -1.65, males -1.14, p<0.001), higher VE/VCO2-slopes (females +0.88, males +0.58, p=0.012) and reduced peak heart rate (females -2.16, males -1.74, p=0.017). Left ventricular parameters did not differ between genders. -Relative to their respective sex-specific healthy controls, derived standard deviation scores in r-ToF suggest that females perform poorer than males in terms of right ventricular systolic function as tested by CMR and exercise capacity. This effect cannot be explained by selection bias. Further outcome data are required from longitudinal cohort studies. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00266188.
    Circulation Cardiovascular Imaging 10/2013; 6(6). DOI:10.1161/CIRCIMAGING.112.000195 · 6.75 Impact Factor
  • The Thoracic and Cardiovascular Surgeon 10/2013; 61(S 02). DOI:10.1055/s-0033-1354534 · 1.08 Impact Factor

Publication Stats

1k Citations
475.91 Total Impact Points

Institutions

  • 2005–2015
    • Berlin Heart
      Berlín, Berlin, Germany
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 2014
    • Otto-von-Guericke-Universität Magdeburg
      • Institut für Biometrie und Medizinische Informatik
      Magdeburg, Saxony-Anhalt, Germany
  • 2012–2014
    • Charité Universitätsmedizin Berlin
      • Department of Pediatrics, Division of Cardiology
      Berlín, Berlin, Germany
    • Deutsche Gesellschaft für Kardiologie – Herz- und Kreislaufforschung e.V.
      Germany
    • Deutsche Gesellschaft für Pädiatrische Kardiologie e.V.
      Düsseldorf, North Rhine-Westphalia, Germany
    • Asklepios Klinik Altona
      Hamburg, Hamburg, Germany
  • 2005–2014
    • Deutsches Herzzentrum Berlin
      • Department of Congenital Heart Disease / Pediatric Cardiology
      Berlín, Berlin, Germany
  • 2013
    • University of Nebraska at Omaha
      • Division of Cardiology
      Omaha, NE, United States
    • University of Nebraska Medical Center
      • Department of Pharmacology and Experimental Neuroscience
      Omaha, Nebraska, United States
  • 2011
    • Competence Network for Congenital Heart Defects
      Berlín, Berlin, Germany
  • 2009
    • Deutsches Herzzentrum München
      München, Bavaria, Germany
  • 2006
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2001–2005
    • University of California, San Francisco
      San Francisco, California, United States
  • 2004
    • Leiden University
      Leyden, South Holland, Netherlands
  • 2003
    • Stanford University
      • Department of Radiology
      Palo Alto, California, United States