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Magnetresonanztomographie bei Trägern künstlicher Herzklappen 1998-Umfrage unter 25 Klappenherstellern sowie Vorstellung der gegenwärtigen Literatur über Sicherheitsaspekte
Die Indikationen zur Magnetresonanztomographie (MRT) bei Trägern künstlicher Herzklappen sind kritisch. Eine generelle Kontraindikation gegen die MRT ist zweifelhaft. Einige diagnostische Fragestellungen wie Prozesse in der hinteren Schädelgrube, Spinalabszesse und bei Beschwerden im Inneren des Knies lassen sich durch die MRT besser untersuchen als mit anderen radiologischen Verfahren. Die MRT kann Träger künstlicher Herzklappen auf dreierlei Weise direkt beeinträchtigen: 1) Bewegung und Dislozierung der Klappenprothese, 2) Erwärmung und 3) Induktion von Arrhythmien durch elektrische Ströme, und indirekt durch eine Verzerrung des MRT-Bildes mit der Gefahr einer diagnostischen Fehlinterpretation. Die gegenwärtige Literatur über Sicherheitsaspekte der MRT bei Trägern künstlicher Herzklappen erscheint nicht ausreichend. Deshalb wurde 1998 eine Umfrage unter fünfundzwanzig Herstellern künstlicher Herzklappen durchgeführt bezüglich der Kompatibilität, Sicherheit, oder der Kontraindikation der MRT ihrer jeweiligen Klappenprothese. Die in Europa führenden Klappen-Hersteller bescheinigten eine MRT-Sicherheit. Einige Firmen stützten ihre Aussagen auf nicht einzusehende Untersuchungen, oder übertrugen die Verantwortung auf den Arzt, der die MRT durchführt. Andere Firmen gaben keine MRT-Sicherheitsgarantie oder antworteten nicht. Zwei Klappenhersteller warnten explizit vor der MRT bei bestimmten Prothesentypen. Aufbauend auf unsere Umfrage wird ein Überblick über die technischen Aspekte, die klinischen Umstände und die Voraussetzungen für MRT-Sicherheitsstandards bei Trägern künstlicher Herzklappen gegeben. The indications for magnetic resonance imaging (MRI) on prosthetic heart valve recipients remain critical. A generalized contraindication for MRI is doubtful. Some diagnostic questions such as interests in pathologies of the posterior cranial fossa, spinal abscesses, and internal derangements for the knee, strongly recommend the advantages of MRI versus all other radiological diagnostic techniques. MRI can directly affect patients with prosthetic valves in three ways by: 1) movement or dislodgment of the prosthesis, 2) heating, and 3) arrhythmias induced by electric currents, and indirectly by distortion of the image and its subsequent misinterpretation. Present literature that concerns the safety considerations of current values appears to be incomplete. Therefore, a survey of twenty-five valve manufacturers with regard to compatibility, safety or contraindication for MRI on their respective prosthetic heart valves was performed in 1998. Those manufacturers who distribute most of the valves in Europe confirmed the safety of MRI. However, some gave their assurances based on inadequate data, or assigned all responsibility to the physician. Some companies did not give any assurance for MRI safety or failed to respond to our enquiry. Two valve manufacturers warned against performing MRI on certain prostheses. Based on our 1998 questionnaire, the technical issues, the clinical circumstances, the prerequisites and criteria for and the definition of safety standards for MRI on prosthetic heart valve recipients are presented in this paper
A promoter polymorphism -945C>G in the connective tissue growth factor in heart failure patients with mechanical circulatory support: a new marker for bridge to recovery?
OBJECTIVES: Mechanical circulatory support (MCS) creates improvement of cardiac function in a small portion of patients with idiopathic dilated cardiomyopathy (iDCM). Among other factors, cardiomyocyte hypertrophy seems to represent an important prerequisite for MCS-related cardiac recovery. We have previously shown that connective tissue growth factor (CTGF) leads to adaptive cardiomyocyte hypertrophy associated with a protective cardiac function in transgenic mice. To test whether a functional genetic variant in the CTGF promoter impacts MCS-related cardiac recovery, three groups of iDCM patients with and without cardiac recovery on MCS were genotyped. METHODS: The CTGF promoter variant (c.-945C>G) was analysed in 314 patients with iDCM receiving medical treatment only (Group I). Forty-nine iDCM patients who were either weaned from MCS for more than 6 months (Group II; n = 20) or bridged to cardiac transplantation (Group III: n = 29) were also genotyped. Patients on MCS were followed up for at least 12 months. Clinical characteristics and outcome on MCS were correlated with the respective genotypes. RESULTS: The c.-945C>G allele frequencies in 314 iDCM patients (Group I) were similar to controls deposited in the HapMap database or those published in a recent study. There were no differences in allele prevalence between patients with mild to moderate iDCM (Group I) compared with patients with severe iDCM requiring MCS (Groups II and III). Intriguingly, 50% of patients who were weaned from MCS (Group II) were homozygous for the G allele compared with only 17.2% of patients included in Group III, which is a significant difference (P = 0.03). CONCLUSIONS: Homozygosity of the promoter-activating G allele in the CTGF_c.-945C>G variant is overrepresented in patients with cardiac recovery on MCS when compared with iDCM patients without cardiac recovery. Further studies are needed to evaluate c.-945C>G as a genetic predictor for clinical outcome on MCS
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