Publikationsserver der RWTH Aachen University
Quantitative Analyse klappeninduzierter Mikroembolien mittels Doppler-Sonographie in vitro für gängige Herzklappenprothesen
Abstract
dc:descriptionPatients with mechanical heart valve prostheses show significantly enhanced numbers of HITS detectet by transcranial Doppler- ultrasound. In order to assess the origin of HITS formation an in vitro study was carried out to quantify valve induced gaseous microemboli for mechanical and bioprosthetic valves at various circulatory conditions by means of Ultrasound-Doppler-Sonography. At the same time the influence of CO2 partial pressure of the fluid on HITS rate was investigated. Circulation was set up as a airtight circulatory mock loop using a cell-free filtered water-glycerol test fluid. Several prosthetic valve types were inserted in mitral position of a left ventricular assist device (MEDOS?). A pulsed ultrasound machine with a dual gated 2 MHz transducer and embolus detection software was used. The ultrasound probe was firm integrated in the circulatory, while detection was performed at two depths to reduce artefacts. For evaluation of the detected microembolic signals, the identification criteria according to the Consensus Committee of the Ninth International Cerebral Hemodynamics Symposium were used. A strong correlation between left ventricular dp/dtmax and detected HITS was shown for mechanical heart valve prostheses. Corresponding to clinical studies it could be demonstrated that a bioprosthesis generates significantly less HITS than a mechnical valve. The measured HITS rates increase by increasing the partial pressure level of CO2 . The results support the hypothesis that cavitation is a key factor for the appearance of gaseous microemboli at heart valve prostheses.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2004
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Schnelke, Christian Joachim
- Contributors dc:contributor
-
- Reul, Helmut
Subjects
dc:subject × 6Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger
Identifiers
dc:identifier.*- OAI identifier oai:identifier
- oai:publications.rwth-aachen.de:59576