J Meyer

Johannes Gutenberg-Universität Mainz, Mainz, Rhineland-Palatinate, Germany

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Publications (663)1861.1 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Das Ziel der Studie war die kernspintomographische Evaluierung koronarer Bypassgefäße mit der Haste- und Fisp-3-D-Angiographiesequenz unter besonderer Berücksichtigung der distalen Bypassanastomose. Eingeschlossen wurden 29 Patienten mit 74 Bypassgefäßen und insgesamt 91 distalen Anastomosen. Eingesetzt wurden eine 2dimensionale, T-2-gewichtete Turbo-Spin-Echo-Sequenz (Haste) sowie eine 3dimensionale, kontrastmittelunterstützte Angiographiesequenz (Fisp-3-D) in Atemanhaltetechnik. Sowohl mit der Haste- als auch der Fisp-3-D-Sequenz konnten 55 der 58 offenen und 15 der 16 verschlossenen Bypässe korrekt beurteilt werden, die Sensitivität und Spezifität betrug 95% und 94%. Überlegen war die Haste-Sequenz (47/63) der Fisp-3-D-Sequenz (40/63) in der Beurteilung der distalen Anastomosen. Bypasstenosen konnten lediglich in 3 von 8 Fälen diagnostiziert werden. Mit der Kernspintomographie ist mit beiden genannten Sequenzen eine nichtinvasive Evaluierung koronarer Bypassgefäße möglich, wobei die Haste-Sequenz in der Beurteilung distaler Bypassanteile überlegen ist. Eine Verbesserung der Aussagekraft der Methode ist durch den Einsatz von gefäßständigen Kontrastmitteln sowie durch die Kombination mit funktionellen Parametern wie der MR-Flußmessung zu erwarten. The aim of the study was to evaluate the patency of coronary artery bypass grafts (CABG) with the 2D and 3D magnetic resonance (MR) imaging techniques. 29 patients with 74 bypass grafts and a total of 91 distal anastomoses were studied on a 1.5 Tesla scanner using a phased array body coil. A 2D T-2 weighted breathhold turbo spin echo sequence (Haste) and a 3D breath hold contrast enhanced MR angiography sequence (Fisp-3-D) were performed. With the Haste and Fisp-3-D sequences 55 of the 58 patent and 15 of the 16 occluded grafts were recognized; the sensitivity and specifity were 95% and 94%, respectively. With the Haste sequence 74% (47/63) and with the Fisp-3-D sequence 64% (40/63) of the distal anastomoses were seen in good image quality. Only 3 of 8 significant grafts stenoses were detected. The patency of CABGs can be evaluated non-invasively with the Haste and the Fisp-3-D angiography sequences. Better results can be expected with the development of a blood-pool contrast medium and the combination of MR flow measurements with imaging techniques. Schlüsselwörter Kernspintomographie – Koronarangiographie – koronare Bypassgefäße – MR-KoronarangiographieKey words Magnetic resonance imaging – coronary angiography – coronary artery bypass grafts – MR – coronary angiography
    Zeitschrift für Kardiologie 05/2012; 89(1):7-14. · 0.97 Impact Factor
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    ABSTRACT: Ziel: Es sollte die Genauigkeit der MR-Phasenkontrastmethode zur Ermittlung des Flusses in Koronararterien und koronaren Bypassgefäßen bestimmt werden. Material und Methode: Die MRT-Flussmessungen von 12 Patienten mit 22 Bypassgefäßen wurden mit intraoperativ mittels Ultraschalldurchflussmethode bestimmten Flüssen verglichen. Präoperativ wurden zusätzlich Flussmessungen in 28 Koronararterien von 20 Patienten durchgeführt. Zur MRT-Flussmessung wurde eine segmentierte 2D-Flash-Sequenz verwendet, die eine zeitliche Auflösung von 110 bzw. 125ms aufwies. Dies ermöglichte die Akquisition von 6–8 Bildpaaren pro Herzzyklus. Ergebnisse: Es bestand eine signifikante Korrelation zwischen den Ergebnissen der intraoperativen und denen der postoperativen MRT-Flussmessung (r=0,76, p<0,0001, t-Test). Das mit der MRT gemessene Flussvolumen lag über dem bei der Ultraschallmessung ermittelten. Die Bestimmung des mittleren Flusses in den Koronararterien zeigte deutliche Unterschiede zwischen Gefäßen mit höhergradiger Stenose (>70%) und Gefäßen ohne Stenose. Die Intra- und Interbeobachtervariabilitäten betrugen 10,5 und 15% (Bypass) bzw. 12,3 und 15,8% (Koronararterien). Schlussfolgerungen: Die Phasenkontrastmethode ermöglicht – in Kenntnis ihrer Limitationen – eine relativ genaue Bestimmung des Blutflusses in Koronararterien und koronaren Bypassgefäßen. Weiterentwicklungen der Methode müssen eine verbesserte räumliche und zeitliche Auflösung zum Ziel haben. Purpose: To evaluate accuracy of velocity encoded cine MR imaging for determination of blood flow in coronary arteries and coronary bypass grafts. Materials and methods: 12 patients with 22 coronary bypass grafts underwent intraoperative flow quantification using the transit time ultrasound method. These values were compared to postoperative MR phase shift measurements. Flow measurements were performed preoperatively in 28 coronary arteries of 20 patients. For flow measurement, we used a velocity-encoded k-space segmented gradient echo sequence with a temporal resolution of 110 or 125ms, respectively. 6–8 pase shift images could be acquired during one cardiac cycle. Results: There was a significant correlation between intraoperative and flow measurements using velocity-encoded MR imaging (r=0.74, p<0.0001, t-test). Flow volumes determined by MR imaging were systemati-cally larger than those determined by the transit time ultrasound method. Mean flow in coronary arteries was reduced in severly stenosed vessels (>70%) compared to normal vessels. Intra- and interobserver vari-ability were 10.5 and 15% (coronary bypass grafts), and 12.3 and 15.8% (coronary ar- teries), respectively. Conclusions: Velocity-encoded MR imaging enables determination of flow in coronary artery bypass grafts and coronary arteries. Future developments should aim at the improvement of spatial and temporal resolution of the method.
    Der Radiologe 04/2012; 40(2):143-149. · 0.47 Impact Factor
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    ABSTRACT: In 12 patients with severe congestive heart failure due to ischaemic heart disease (n=6) and due to congestive cardiomyopathy (n=6) the haemodynamic effects of a new β1–agonist, prenalterol, were studied. Left ventricular (LV) function was studied before and 20 min after infusion of 12 mg prenalterol. Heart rate was kept constant by atrial pacing at a rate of 100 min−1 unless intrinsic heart rate exceeded it.As a sign of positive inotropic support, prenalterol enhanced peak rate of LV pressure development (dP/dt) from 1160+100 mm Hg/s to 1590 ± 190 mm Hg/s (p > 0.005). In the mean LV end–diastolic and end–systolic volume determined by cineventriculography and two–dimensional echocardiography decreased. LV stroke work index measured with both methods increased with 4 ml/m2 and 5 ml/m2, respectively (p > 0.02). LV ejection fraction was improved by 6% and 8% (p > 0.005). Increase of peak fall of left ventricular pressure (dP/dt) (1050+60 mm Hg/s to 1270+100 mm Hg/s, p > 0.005) and shortening of time constant (T) of pressure fall from 64.5 ± 5.0 ms to 44.5 ± 6.0 ms (p > 0.005) demonstrated the improved LV relaxation. Analysis of LV volume and myocardial compliance revealed decrease of left ventricular stiffness. Thus, LV filling pressure was reduced from 22.1 ± 4 mm Hg to 14 ± 3.5 mm Hg (p > 0.001). Pressure volume analysis showed a significant increase of LV power and work, as well as a slight decrease of wall stress.Our study could demonstrate, even in patients with severe heart failure, a sustained positive inotropic effect of prenalterol leading to an improved left ventricular contractility, relaxation and compliance. LV power and work was enhanced. The increase of oxygen demand seemed to be counterbalanced by an improved perfusion of particularly subendocardial layers indicated by an increased transmyocardial pressure gradient.
    Journal of Internal Medicine 01/2009; 211:169-180. · 6.46 Impact Factor
  • 12/2005: pages 27-142;
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    ABSTRACT: Microbe-induced (infectious) endocarditis is an endovascular infection, caused mainly by bacteria, of cardiovascular structures. The major predilection site are the native heart valves, but involvement of implanted intracardiac foreign material is increasingly being seen. The mortality rate of infectious endocarditis depends on clinical factors and the causal agent, but also on the time of the establishment of the diagnosis and the initiation of appropriate treatment. In Germany, the current mortality rate ranges up to 18%. Between January 2003 and July 2004, with the aim of improving patient care and thus the outcome of this condition, a guideline commission worked out recommendations for the diagnosis, treatment and management of the disease for the use of general practitioners and hospital physicians, in particular microbiologists, infectiologists, cardiologists and cardiac surgeons. The basis for this guideline was the systematic search through the literature of the European guideline. On the 16th and 28th of June 2004, the entire guideline was formerly approved in a nominal group process.
    MMW Fortschritte der Medizin 01/2005; 146(Suppl 3-4):123-35.
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    ABSTRACT: Carotid stenosis is frequent in patients with coronary artery disease (CAD). In the literature, 9-28% of patients with CAD have additional carotid artery stenosis, predictors of which are advanced age, smoking, diabetes mellitus, arterial hypertension, coronary multivessel disease, and peripheral arterial disease. Moreover, patients with unstable coronary syndromes and those with elevated inflammatory markers such as C-reactive protein or fibrinogen more often have concomitant CAD and carotid artery stenosis. The long-term prognosis of these patients is worse than with CAD only. Therefore, patients with CAD should be screened for additional carotid artery stenosis, especially if coronary artery bypass grafting is planned. Continuous wave Doppler sonography and color-coded duplex sonography are suitable methods to screen for carotid artery stenosis.
    Der Chirurg 08/2004; 75(7):667-71. · 0.52 Impact Factor
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    ABSTRACT: Eine Karotisstenose ist ein hufiger Zusatzbefund bei Patienten mit koronarer Herzerkrankung (KHK). Nach Literaturangaben kann bei 9–28% der Patienten mit KHK eine zustzliche Stenose der Karotisstrombahn diagnostiziert werden. Prdiktoren fr die Koinzidenz einer Karotisstenose und KHK sind ein fortgeschrittenes Alter, Rauchen, Diabetes mellitus, arterielle Hypertonie, das Vorliegen einer koronaren Mehrgeferkrankung und eine periphere arterielle Verschlusserkrankung. Auch bei Patienten mit instabilem Koronarsyndrom und bei erhhten laborchemischen Inflammationsmarkern wie dem C-reaktiven Protein oder Fibrinogen ist hufiger eine zustzliche Karotisstenose nachweisbar. Das Vorliegen einer zustzlichen Karotisstenose fhrt zu einer signifikanten Verschlechterung der Gesamtprognose. Patienten mit einer KHK sollten daher zustzlich auf das Vorliegen einer Karotisstenose untersucht werden, insbesondere wenn eine Koronarbypass-Operation vorgesehen ist. Als geeignete Screeningmethode stehen uns hier die cw-Dopplersonographie und farbkodierte Duplexsonographie zur Verfgung.Carotid stenosis is frequent in patients with coronary artery disease (CAD). In the literature, 9–28% of patients with CAD have additional carotid artery stenosis, predictors of which are advanced age, smoking, diabetes mellitus, arterial hypertension, coronary multivessel disease, and peripheral arterial disease. Moreover, patients with unstable coronary syndromes and those with elevated inflammatory markers such as C-reactive protein or fibrinogen more often have concomitant CAD and carotid artery stenosis. The long-term prognosis of these patients is worse than with CAD only. Therefore, patients with CAD should be screened for additional carotid artery stenosis, especially if coronary artery bypass grafting is planned. Continuous wave Doppler sonography and color-coded duplex sonography are suitable methods to screen for carotid artery stenosis.
    Der Chirurg 06/2004; 75(7):667-671. · 0.52 Impact Factor
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    ABSTRACT: P-selectin and P-selectin glycoprotein ligand (SELPLG, selectin P ligand) constitute a receptor/ligand complex that is likely to be involved in the development of atherosclerosis and its complications. While the genetic variability of P-selectin has already been investigated in depth, that of the SELPLG gene has not yet been extensively explored. The coding and regulatory sequences of the SELPLG were screened and nine polymorphisms were identified. The identified polymorphisms were genotyped in the AtheroGene study, a case-control study of coronary artery disease (CAD). Haplotype analysis revealed that two polymorphisms of SELPLG, the M62I and the VNTR, independently influenced plasma SELPLG levels. Conversely, haplotypes of SELPLG were not associated with CAD risk.
    Annals of Human Genetics 12/2003; 67(Pt 6):504-11. · 2.22 Impact Factor
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    ABSTRACT: The aim of this follow-up study was to investigate the late effects of acute coronary angioplasty (PTCA) on regional wall motion after the subacute phase of myocardial infarction (MI). Seventeen patients were investigated initially at a median of 11 days and again at 6 months after acute PTCA for myocardial infarction (< 8 hours after onset of symptoms) by cardiac magnetic resonance imaging. Corresponding short-axis slices encompassing the left ventricle (LV) were acquired using a standard cine MR for regional wall motion analysis and using delayed contrast enhanced magnetic resonance imaging (ceMRI) for infarct size quantification. The infarct size was similar in the subacute phase and the 6 month follow-up (20.8 and 21.9%, respectively; n.s.). Regional wall motion improved significantly in the area of hyperenhancement [percentage wall thickening (PWT) 21.9% and 37.9%, p < 0.05] in contrast to remote normal myocardium (46.4% and 38.4%; n.s.). Regional wall motion was significantly poorer in transmural compared with nontransmural MI in the subacute stage, and a late improvement could only be observed in transmural MI. Transmural areas of hyperenhancement displayed significant late long-term improvement of regional wall motion after acute PTCA, possibly related to prolonged stunning compared with nontransmural areas.
    Journal of Cardiovascular Magnetic Resonance 07/2003; 5(3):487-95. · 4.44 Impact Factor
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    ABSTRACT: Primary tumors of the heart are rare, whereas cardiac metastases, most frequently from adenocarcinomas, occur in up to 20% of malignant tumors. We report about a 61-year-old female patient who was admitted with recurrent stress-induced dizziness, intermittent tachycardia and a fall due to a pre-syncope. Echocardiography showed a left atrial tumor with the typical features of a pediculated myxoma, leading to open heart surgery. However, histopathology revealed a 2.2 x 1.5 cm adenocarcinoma. The subsequent search for a primary tumor, including tumor markers and (18)F-FDG-PET, was unsuccessful, as was a second thorough diagnostic workup half a year later. The tumor was therefore classified as a primary cardiac adenocarcinoma.
    Zeitschrift für Kardiologie 04/2003; 92(3):254-9. · 0.97 Impact Factor
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    ABSTRACT: Stored electrograms (EGM) have recently been introduced into pacemaker therapy. New generation devices offer the possibility to store the onset of the EGM (several seconds preceding storage trigger) and marker annotations. The aim of the study was to evaluate whether the diagnostic capabilities of EGMs are improved by these new features. We studied 65 patients (age 68+/-12 years, 41 male) implanted with a DDDR-system (PulsarMax II 1280; Guidant). During a 1-month period 319 EGMs have been recorded. EGM triggers were: Ventricular Tachycardia (VT), Non-Sustained VT (NSVT), Atrial Tachycardia Response (ATR), Pacemaker Mediated Tachycardia (PMT) and Sudden Bradycardia Response (SBR). First, each EGM was analysed with onset and markers blinded. EGMs were classified with respect to their trigger as confirmed, not-confirmed or false-positive. Analysis was then repeated with markers visible but without onset, and thereafter vice versa. Finally, EGMs were analysed with both features. It was noted whether the presence of marker annotations and/or onset-recording changed the initial classification of the stored EGMs. 169 EGMs were triggered by SBR, which can only be confirmed with onset recording. False positive EGMs (atrial undersensing) occurred in 12%. The remaining 150 EGMs were triggered by ATR (80%), NSVT (11%), VT (6%) and by PMT (3%). Without onset/markers 37 of these 150 EGMs (25%) could not be confirmed. With markers and onset 33/37 (89%) of these EGMs could now be classified as confirmed or false positive. These EGMs became diagnostic with onset alone in 24%, with markers alone in 24%, and with the combination of both in 41%. In 4 EGMs no definite diagnosis could be established. Stored electrograms provide direct insights into device function, thereby providing a validation of diagnostic data. The expanded recording of onset and markers results in markedly improved diagnostic capabilities - compared with conventional EGMs. These new features were necessary to interpret correctly 61% of all stored electrograms, without which a diagnosis would not have been possible. Both onset-recording and marker annotation are necessary for optimal analysis.
    Europace 02/2003; 5(1):103-9. · 2.77 Impact Factor
  • Zeitschrift für Kardiologie 02/2003; 92(1):104-10. · 0.97 Impact Factor
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    01/2003;
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    ABSTRACT: Objective: The aim was the study was to evaluate the patency of coronary artery bypass grafts with the 3D Navigator and the Haste magnetic resonance imaging techniques. Material and methods: Thirty-four patients with 82 grafts (18 internal mammarian artery and 64 saphenous venous grafts) were examined at 1.5 T using a phased arrray body coil. A 2D T-2 weighted turbo spin echo sequence (Haste) and a 3D-angiography sequence in navigator technique were used. Reference method was the conventional coronary angiography that was performed within 7 days. Results: With the HASTE sequence 54 of 56 patent and 12 of the 16 occluded grafts were recognized, the sensitivity and specificity was 96 and 75%. The distal anastomosis could be assessed in 28 of 76 cases. With the Haste sequence 54 of the 56 patent and 12 of the 14 occluded grafts were detected correctly. Eight patent and two occluded grafts were judged as not assessable. The sensitivity and specificity was 96 and 85%. Sixty-six percent (50/76) of the distal anastomosis were identified correctly. With both sequences none of the bypass stenosis could be detected. Conclusions: The patency of coronary bypass grafts can be evaluated noninvasively with a sensitivity of 96% and a specificity of 76%. No inference can be made with respect to the nature of bypass graft stenosis. Better results can be expected with the development of a blood pool contrast medium, an improvement of the spatial resolution and in the combination of flow measurements.
    The International Journal of Cardiovascular Imaging 11/2002; 18(6):469-477. · 2.65 Impact Factor
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    ABSTRACT: We compared the qualitative Thombolysis in Myocardial Infarction (TIMI) Flow Classification with a new quantitative method, the TIMI Frame Count, to investigate the differences of both systems in detecting coronary flow changes after stent implantation. TIMI flow grades and corrected TIMI frame counts (CTFC) were determined in 102 patients before, after stent implantation and at 6-month angiography. Analysis of the CTFC in patients with TIMI flow grades 3 and 2 demonstrated that for CTFC values lower than 30 frames, all patients had TIMI flow grade 3, while for CTFC values greater than 69 frames no patient had TIMI grade 3 flow. For CTFC values between 30 and 69 frames, TIMI grades 3 and 2 flow overlap. Comparing changes in TIMI flow grades and the CTFC before and after stent implantation (after stent implantation and at 6 month angiography), CTFC detects flow changes in 46% (40%) of the patients, which were not detected with TIMI Flow Classification. The TIMI Flow Classification grading system is not able to separate clearly between completely perfused and partially perfused coronary artery vessels. The quantitative TIMI Frame Count method is superior to the qualitative TIMI Flow Classification in detecting coronary flow changes.
    The Journal of invasive cardiology 11/2002; 14(10):590-6. · 1.57 Impact Factor
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    ABSTRACT: Background: The aim of our study was to investigate the efficacy of the combination of clopidogrel and aspirin in the prevention of thrombus formation on artificial heart valves in an experimental rabbit model as compared to anticoagulation with warfarin. Methods: Studies were performed after oral administration of clopidogrel and aspirin in group I (n=9) for 5 days, after 5±2 days treatment with warfarin in group II (n=9) and without medication in group III (n=9). Leaflets from Sulzer Carbomedics bileaflet valves were placed in a flow chamber. The flow chamber was filled with blood in a continuous circulation between the carotid artery and the jugular vein. Results: In group III, the flow chamber was clotted after a median of 15 min of circulation. Weight analysis before and after 1 h of perfusion showed that the median thrombus weight was 9.1 mg in group I, 14.4 mg in group II and 33.7 mg in group III. Further analysis by electron microscopy showed fewer platelets and erythrocytes on leaflets in group I than on leaflet surfaces in group II. Conclusion: Clopidogrel and aspirin were more effective than warfarin in preventing thrombus formation on artificial heart valve leaflets in our investigation. This rabbit model with a high dosage of clopidogrel and aspirin, and a short-time exposure of the heart valve leaflets to rabbit blood under laminar flow, should be further evaluated with respect to whether it can give information about antithrombotic regimens in patients after mechanical heart valve replacement.
    Thrombosis Research 08/2002; · 3.13 Impact Factor
  • H J Rupprecht, J Meyer
    Der Internist 05/2002; 43 Suppl 1:S90-5. · 0.33 Impact Factor
  • DMW - Deutsche Medizinische Wochenschrift 05/2002; 127(14):729-35. · 0.65 Impact Factor
  • H. J. Rupprecht, J. Meyer
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    ABSTRACT: Zum Thema In der Regel liegt dem transmuralen Myokardinfarkt (ST-Hebungsinfarkt) die Ruptur einer atherosklerotischen Plaque mit nachfolgend thrombotischem Verschluss einer Koronararterie zugrunde. Seit Beginn der 1980er Jahre hat die Reperfusionstherapie bei akutem Myokardinfarkt zunehmend Eingang in die klinische Routine gefunden. Als Standardtherapie hat sich die intravense Thrombolysetherapie durchgesetzt. Je frhzeitiger die Reperfusion einsetzt, um so mehr Myokardgewebe kann vor der drohenden Nekrose bewahrt werden. Diese erzielbare Verringerung der Infarktgre geht mit einer Verringerung der sonst drohenden linksventrikulren Funktionseinschrnkung und einer Abnahme der Letalitt einher. Letzteres konnte in randomisierten, placebokontrollierten Studien bei mehr als 60.000 Patienten belegt werden. Darber hinaus konnte gezeigt werden, dass nur die vollstndige, unbehinderte Reperfusion mit einer Prognoseverbesserung einhergeht. Durch geeignete antithrombotische Begleittherapien kann der Gefahr einer Reokklusion entgegengewirkt werden. Das Ziel der Reperfusionsbehandlung ist zusammenfassend also die frhe, vollstndige und anhaltende Reperfusion des Infarktgefes.
    Der Internist 03/2002; 43:S90-S95. · 0.33 Impact Factor
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    ABSTRACT: Comparison between two semiquantitative methods and a quantitative evaluation of myocardial blood flow (MBF) for assessment of myocardial perfusion reserve (MPR) in patients with CAD. 9 patients with coronary stenoses > 50 % were examined with an ECG-gated Saturation Recovery Turbo FLASH sequence by using Gd-DTPA as contrast agent (CA). The entive measurements were performed both during rest and hyperemia induced by adenosine. The up-slopes of the signal-time S(t) curves in the myocardium and left ventricular (LV) cavity were evaluated by a linear fit. MPR was calculated from the original up-slopes of the myocardial S(t) curves and from the up-slopes, which were normalized to the up-slopes of the LV S(t) curves, respectively. For quantification of MBF values, the mathematical model MMID 4 was used and MPR was evaluated from the MBF values. With all tested methods, MPR was reduced in myocardial regions subtended by arteries with stenoses >/= 70 % compared with remote regions. With MMID 4 and the normalized up-slope method, differences between severe ischemic and remote regions were statistically significant. The up-slope method with normalization and quantification with MMID 4 are more sensitive methods to differentiate between remote and ischemic myocardium than the up-slope method without normalization.
    RöFo - Fortschritte auf dem Gebiet der R 03/2002; 174(2):187-95. · 2.76 Impact Factor

Publication Stats

6k Citations
1,861.10 Total Impact Points

Institutions

  • 1986–2012
    • Johannes Gutenberg-Universität Mainz
      • III. Department of Medicine
      Mainz, Rhineland-Palatinate, Germany
  • 1993–2001
    • University of Duisburg-Essen
      • Department of Internal and Integrative Medicine
      Essen, North Rhine-Westphalia, Germany
  • 2000
    • William Harvey Research Institute
      Londinium, England, United Kingdom
  • 1998–1999
    • Maastricht University
      • Department of Cardiology
      Maastricht, Provincie Limburg, Netherlands
    • Martin-Luther Hospital
      Berlín, Berlin, Germany
    • Catharina Hospital
      Eindhoven, North Brabant, Netherlands
  • 1993–1997
    • University Hospital Essen
      Essen, North Rhine-Westphalia, Germany
  • 1994
    • Universitätsklinikum Jena
      Jena, Thuringia, Germany
    • Georgetown University
      • Department of Pharmacology
      Washington, D. C., DC, United States
  • 1992
    • Hospital Clínico San Carlos
      • Servicio de Cardiología
      Madrid, Madrid, Spain
  • 1975–1989
    • RWTH Aachen University
      Aachen, North Rhine-Westphalia, Germany
    • Texas Heart Institute
      • Division of Cardiovascular Surgery
      Houston, Texas, United States
    • Texas Children's Hospital
      Houston, Texas, United States
  • 1988
    • Landeskrankenhaus Graz
      Gratz, Styria, Austria
  • 1981–1983
    • University Hospital RWTH Aachen
      Aachen, North Rhine-Westphalia, Germany