Publications by authors named "Olaf Muehling"

Objective: Idiopathic pulmonary arterial hypertension (IPAH) remains a devastating and incurable, albeit treatable condition. Treatment response is not uniform and parameters that help to anticipate a rather benign or a malignant course of the disease are warranted. Acute pulmonary vasoreactivity testing during right heart catheterisation is recommended to identify a minority of patients with IPAH with sustained response to calcium channel blocker therapy.

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Background: Conventional cardiac pacemakers are still often regarded as a contraindication to magnetic resonance imaging (MRI). We conducted this study to support the hypothesis that it is safe to scan patients with cardiac pacemakers in a 1.5 Tesla MRI, if close supervision and monitoring as well as adequate pre- and postscan programming is provided.

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Purpose of this survey was to estimate the value of MRI for the assessment of the anatomical and functional features of sinus venosus atrial septal defect (SVD). This prospective study included 13 surgically proven cases of SVD out of 81 subjects submitted to MRI due to inconclusive transthoracic echocardiography (TTE) or suspicion of high intracardiac and/or extracardiac shunt volumes based on echocardiographic findings. MRI examination included cine SSFP sequences, contrast-enhanced 3D gradient-echo (GE) sequences for MR angiography (MRA) and phase-contrast flow-measurements.

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Objective: The aim of our study was to show that spatial resolution can be improved without loss of diagnostic accuracy if a 3D inversion recovery gradient-recalled echo (GRE) sequence is used instead of a segmented inversion recovery GRE at 3 T for the assessment of myocardial infarction.

Subjects And Methods: Fifteen patients with myocardial infarction were examined on a 3-T MR system. A segmented breath-hold 3D inversion recovery GRE technique with a voxel size of 6.

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Extensive research has documented that rapid imaging during the first pass of a magnetic resonance imaging (MRI) contrast agent provides good sensitivity to detect myocardial blood flow deficits caused by coronary disease, cardiomyopathies, or microvascular dysfunction in patients without obstructive lesions in the coronary arteries. The autoregulatory mechanisms of the coronary circulation serve the purpose of maintaining sufficient blood flow at baseline in the presence of flow-obstructing coronary lesions. Stress testing is most commonly used in this setting to determine the hemodynamic effect of coronary lesions in the epicardial arteries when the small-vessel resistance has been minimized by vasodilation.

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A stereoselective route to enantiomerically enriched bicyclic cyclopropane derivatives 13 is described which is based on a conceptually novel 1,2-chirality transfer approach. The hyperconjugative interaction of an electronically excited carbonyl group with the sigma* orbital of an adjacent C--X bond in the transition state of a hydrogen abstraction causes the preference of a certain conformation and consequently the differentiation between two diastereotopic methylene groups. The 1,2-chirality transfer is completed by a subsequent HX elimination which destroys the only stereogenic center in the reactants 12.

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Purpose: The aim of the study was to assess the diagnostic accuracy of imaging myocardial infarction with a single-shot inversion recovery turbofast low-angle shot (SS IR turboFLASH) sequence at 3.0 Tesla in comparison with an established segmented inversion recovery turboFLASH sequence at 1.5 Tesla.

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Background: N-terminal pro-brain natriuretic peptide (NT-proBNP) is a byproduct of the brain natriuretic peptide (BNP) that was shown to be of prognostic value in pulmonary hypertension (PH). The role of NT-proBNP in PH has to be determined, especially under the influence of renal impairment that might lead to an accumulation of the peptide, and may be a sign of increased mortality per se.

Methods: We assessed NT-proBNP, BNP, renal function, and hemodynamic parameters (during right-heart catheterization) in 118 consecutive patients with isolated PH, excluding left-heart disease.

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Background: Angiographic collateral vessel filling is limited to evaluate collateral-dependent myocardium. We hypothesize, that quantitative assessment of regional myocardial function, perfusion and viability with Cardiac Magnetic Resonance (CMR) adds complementary information to angiography of collateralized myocardium.

Methods: CMR was performed in 30 patients with one chronic occluded coronary artery and no further flow limiting stenosis to assess transmural extend of infarction (TEI), resting perfusion and perfusion during adenosine-induced hyperemia and regional wall thickening (RWT) in collateral-dependent and antegradely-perfused myocardium.

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In the present study, we describe the photochemical behaviour of 2-mesyloxy phenyl ketones 8 and 12 bearing a cyclopropane moiety in the side-chain. Irradiation of 8 and 12 leads to the corresponding benzoyl spiro[2.2]pentanes as a consequence of an initial gamma-H-shift, subsequent elimination of MsOH (accompanied by a spin-center shift) and cyclization of the resulting 1,3-diradicals.

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An overwhelming number of myocardial perfusion studies are done by nuclear isotope imaging. Magnetic resonance imaging during the first pass of an injected, contrast bolus has some significant advantages for detection of blood flow deficits, namely higher spatial resolution, absence of ionizing radiation, and speed of the test. Previous clinical studies have demonstrated that excellent sensitivity and specificity can be achieved with MR myocardial perfusion imaging for detecting coronary artery disease, and assessment of patients with acute chest pain.

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Background: Dobutamine stress MR (DSMR) is increasingly used in the clinical routine. Due to the limitations inherent to MR, i.e.

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The knowledge of myocardial perfusion in healthy volunteers is fundamental for evaluation of patients with ischemic heart disease. The study was conducted to determine range, regional variability, and transmural gradient of myocardial perfusion in normal volunteers with Magnetic Resonance Perfusion Imaging (MRPI). Perfusion was assessed in 17 healthy volunteers (age: 20-47 yr, 11 males) at rest and adenosine-induced hyperemia using a 1.

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Objectives: The goal of this study was to detect transplant arteriopathy (Tx-CHD) by a reduced myocardial perfusion reserve (MPR) and resting endomyocardial/epimyocardial perfusion ratio (Endo/Epi ratio).

Background: Transplant arteriopathy often lacks clinical symptoms and is the reason for frequent surveillance angiography in heart transplant (Tx) recipients. Magnetic resonance perfusion imaging (MRPI) allows noninvasive assessment of transmural and selective endomyocardial and epimyocardial perfusion.

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