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Towards real-time cardiovascular magnetic resonance-guided transarterial aortic valve implantation: In vitro evaluation and modification of existing devices

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      Abstract

      Background

      Cardiovascular magnetic resonance (CMR) is considered an attractive alternative for guiding transarterial aortic valve implantation (TAVI) featuring unlimited scan plane orientation and unsurpassed soft-tissue contrast with simultaneous device visualization. We sought to evaluate the CMR characteristics of both currently commercially available transcatheter heart valves (Edwards SAPIEN™, Medtronic CoreValve ®) including their dedicated delivery devices and of a custom-built, CMR-compatible delivery device for the Medtronic CoreValve ® prosthesis as an initial step towards real-time CMR-guided TAVI.

      Methods

      The devices were systematically examined in phantom models on a 1.5-Tesla scanner using high-resolution T 1-weighted 3D FLASH, real-time TrueFISP and flow-sensitive phase-contrast sequences. Images were analyzed for device visualization quality, device-related susceptibility artifacts, and radiofrequency signal shielding.

      Results

      CMR revealed major susceptibility artifacts for the two commercial delivery devices caused by considerable metal braiding and precluding in vivo application. The stainless steel-based Edwards SAPIEN™ prosthesis was also regarded not suitable for CMR-guided TAVI due to susceptibility artifacts exceeding the valve's dimensions and hindering an exact placement. In contrast, the nitinol-based Medtronic CoreValve ® prosthesis was excellently visualized with delineation even of small details and, thus, regarded suitable for CMR-guided TAVI, particularly since reengineering of its delivery device toward CMR-compatibility resulted in artifact elimination and excellent visualization during catheter movement and valve deployment on real-time TrueFISP imaging. Reliable flow measurements could be performed for both stent-valves after deployment using phase-contrast sequences.

      Conclusions

      The present study shows that the Medtronic CoreValve ® prosthesis is potentially suited for real-time CMR-guided placement in vivo after suggested design modifications of the delivery system.

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      Most cited references 31

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      Acute kidney injury following transcatheter aortic valve implantation: predictive factors, prognostic value, and comparison with surgical aortic valve replacement

      Aims Very few data exist on the occurrence of acute kidney injury (AKI) associated with transcatheter aortic valve implantation (TAVI). The objectives of the present study were (i) to determine the incidence, predictive factors, and prognostic value of AKI following TAVI, and (ii) to compare the occurrence of AKI in TAVI vs. surgical aortic valve replacement (SAVR) in patients with pre-procedural chronic kidney disease (CKD). Methods and results A total of 213 patients (mean age 82 ± 8 years) undergoing TAVI for the treatment of severe aortic stenosis were included in the study. Acute kidney injury was defined as a reduction of >25% in estimated glomerular filtration rate (eGFR) within 48 h following the procedure or the need for haemodialysis during index hospitalization. Those patients with pre-procedural CKD (eGFR <60 mL/min/1.73 m2, n = 119) were compared with 104 contemporary patients with CKD who underwent isolated SAVR. The incidence of AKI following TAVI was 11.7%, with 1.4% of the patients requiring haemodialysis. Predictive factors of AKI were hypertension (OR: 4.66; 95% CI: 1.04–20.87), chronic obstructive pulmonary disease (OR: 2.64, 95% CI: 1.10–6.36), and peri-operative blood transfusion (OR: 3.47, 95% CI: 1.30–9.29). Twenty-one patients (9.8%) died during index hospitalization, and the logistic EuroSCORE (OR: 1.03 for each increase of 1%; 95% CI: 1.01–1.06) and occurrence of AKI (OR: 4.14, 95% CI: 1.42–12.13) were identified as independent predictors of postoperative mortality. Patients with CKD who underwent TAVI were older, had a higher logistic EuroSCORE and lower pre-procedural eGFR values compared with those who underwent SAVR (P < 0.0001 for all). The incidence of AKI was lower (P = 0.001; P = 0.014 after propensity score adjustment) in CKD patients who underwent TAVI (9.2%, need for haemodialysis: 2.5%) compared with those who underwent SAVR (25.9%, need for haemodialysis: 8.7%). Conclusion Acute kidney injury occurred in 11.7% of the patients following TAVI and was associated with a greater than four-fold increase in the risk of postoperative mortality. Hypertension, chronic obstructive pulmonary disease, and blood transfusion were predictive factors of AKI. In those patients with pre-procedural CKD, TAVI was associated with a significant reduction of AKI compared with SAVR.
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        Applications of phase-contrast flow and velocity imaging in cardiovascular MRI.

        A review of cardiovascular clinical and research applications of MRI phase-contrast velocity imaging, also known as velocity mapping or flow imaging. Phase-contrast basic principles, advantages, limitations, common pitfalls and artefacts are described. It can measure many different aspects of the complicated blood flow in the heart and vessels: volume flow (cardiac output, shunt, valve regurgitation), peak blood velocity (for stenosis), patterns and timings of velocity waveforms and flow distributions within heart chambers (abnormal ventricular function) and vessels (pulse-wave velocity, vessel wall disease). The review includes phase-contrast applications in cardiac function, heart valves, congenital heart diseases, major blood vessels, coronary arteries and myocardial wall velocity.
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          Transcatheter aortic valve implantation: impact on clinical and valve-related outcomes.

          Transcatheter aortic valve implantation is an alternative to open heart surgery in patients with aortic stenosis. However, long-term data on a programmatic approach to aortic valve implantation remain sparse. Transcatheter aortic valve implantation was performed in 168 patients (median age, 84 years) in the setting of severe aortic stenosis and high surgical risk. Access was transarterial (n=113) or, in the presence of small iliofemoral artery diameter, transapical (n=55). The overall success rate was 94.1% in this early experience. Intraprocedural mortality was 1.2%. Operative (30-day) mortality was 11.3%, lower in the transarterial group than the transapical group (8.0% versus 18.2%; P=0.07). Overall mortality fell from 14.3% in the initial half to 8.3% in the second half of the experience, from 12.3% to 3.6% (P=0.16) in transarterial patients and from 25% to 11.1% (P=0.30) in transapical patients. Functional class improved over the 1-year postprocedure period (P 3 years and a median of 221 days, structural valve failure was not observed. Transcatheter aortic valve implantation can result in early and sustained functional improvement in high-risk aortic stenosis patients. Late outcome is determined primarily by comorbidities unrelated to aortic valve disease.
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            Author and article information

            Affiliations
            [1 ]Department of Cardiology, West-German Heart Center Essen, University Hospital Essen, University Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
            [2 ]Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
            [3 ]Evasc Medical Systems, 107-1099 West 8th Avenue, Vancouver, BC V6H 1C3, Canada
            [4 ]Institute of Medical Physics, Friedrich-Alexander University Erlangen-Nürnberg, Henkestrasse 91, 91052 Erlangen, Germany
            Contributors
            Journal
            J Cardiovasc Magn Reson
            Journal of Cardiovascular Magnetic Resonance
            BioMed Central
            1097-6647
            1532-429X
            2010
            13 October 2010
            : 12
            : 1
            : 58
            2964701
            1532-429X-12-58
            20942968
            10.1186/1532-429X-12-58
            Copyright ©2010 Kahlert et al; licensee BioMed Central Ltd.

            This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

            Categories
            Research

            Cardiovascular Medicine

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