TY  - JOUR
A1  - Reiter, Theresa
A1  - Gensler, Daniel
A1  - Ritter, Oliver
A1  - Weiss, Ingo
A1  - Geistert, Wolfgang
A1  - Kaufmann, Ralf
A1  - Hoffmeister, Sabine
A1  - Friedrich, Michael T.
A1  - Wintzheimer, Stefan
A1  - Düring, Markus
A1  - Nordbeck, Peter
A1  - Jakob, Peter M.
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
A1  - Bauer, Wolfgang R.
T1  - Direct cooling of the catheter tip increases safety for CMR-guided electrophysiological procedures
JF  - Journal of Cardiovascular Magnetic Resonance
N2  - 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.
KW  - EP Procedures
KW  - radiofrequency ablation
KW  - contact force
KW  - lesion size
KW  - MRI
KW  - temperature
KW  - tissue
KW  - wires
KW  - model
KW  - ablation
KW  - safety
KW  - catheter tip
KW  - MR guidance
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134927
VL  - 14
IS  - 12
ER  - 
TY  - THES
A1  - Krauspe, Jan Christian
T1  - MR-tomographische Analyse des linksventrikulären Remodellings nach Myokardinfarkt
T1  - MRI-Analysis of left ventricular remodeling after myocardial infarction
N2  - Die Myokardausdehnung wird als neuer Parameter der Infarktanatomie eingeführt. Dessen Entwicklung über die Zeit korreliert in hohem Maße mit der Entwicklung des enddiastolischen Volumens. Beide gemeinsam, die Myokardausdehnung und die Infarktausdehnung, bestimmen die Entwicklung des enddiastolischen Volumens im Laufe des linksventrikulären Remodellings nach Myokardinfarkt. Neben den bekannten verschiedenen Formen der Dilatation des linken Ventrikels kommt es bei zahlreichen Patienten auch zu einem Rückgang des enddiastolischen Volumens im Verlauf des Remodellings.
N2  - Anatomy of myocardial infarction and the development of enddiastolic volume can be illustrated in by comparing remote extent und infarct extent during remodeling. Expansion of infarcted and remote myocardium following myocardial infarction may be viewed as variable repair and compensatory mechanisms, that are independent of each other. There is not only dilatation of left ventricular volume but also shrinking.
KW  - Herzinfarkt
KW  - NMR-Tomographie
KW  - Krankheitsverlauf
KW  - Enddiastolisches Volumen
KW  - Dilatation
KW  - Verringerung
KW  - MRI
KW  - myokardial infarction
KW  - remodeling
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-72905
ER  -