Thilo Noack

An integrated framework for finite-element modeling of mitral valve biomechanics from medical images: Application to MitralClip intervention planning

Treatment of mitral valve (MV) diseases requires comprehensive clinical evaluation and therapy personalization to optimize outcomes. Finite-element models (FEMs) of MV physiology have been proposed to study the biomechanical impact of MV repair, but their translation into the clinics remains challenging. As a step towards this goal, we present an integrated framework for finite-element modeling of the MV closure based on patient-specific anatomies and boundary conditions. Starting from temporal medical images, we estimate a comprehensive model of the MV apparatus dynamics, including papillary tips, using a machine-learning approach. A detailed model of the open MV at end-diastole is then computed, which is finally closed according to a FEM of MV biomechanics. The motion of the mitral annulus and papillary tips are constrained from the image data for increased accuracy. A sensitivity analysis of our system shows that chordae rest length and boundary conditions have a significant influence upon the simulation results. We quantitatively test the generalization of our framework on 25 consecutive patients. Comparisons between the simulated closed valve and ground truth show encouraging results (average point-to-mesh distance: 1.49 ± 0.62 mm) but also the need for personalization of tissue properties, as illustrated in three patients. Finally, the predictive power of our model is tested on one patient who underwent MitralClip by comparing the simulated intervention with the real outcome in terms of MV closure, yielding promising prediction. By providing an integrated way to perform MV simulation, our framework may constitute a surrogate tool for model validation and therapy planning.

Trans-apical beating-heart implantation of neo-chordae to mitral valve leaflets: results of an acute animal study.

OBJECTIVEnTrans-apical beating-heart implantation of neo-chordae is yet an experimental procedure for mitral valve (MV) repair. We aimed to assess the performance of a new device in an acute animal study.nnnMETHODSnA total of four domestic adolescent pigs were used as an acute model. The MV was assessed on the beating heart through a conventional trans-apical access. The NeoChord DS1000 device was used to implant polytetrafluoroethylene (PTFE) sutures to the MV leaflets. Procedural performance of the device was assessed and completed with surgical workflow analysis.nnnRESULTSnOverall 57 implantations using epicardial echocardiography guidance were performed (mean 14.3 implantations per animal). The MV leaflets were successfully grasped every second attempt (mean 2.3±1.9) with no difference between the anterior and the posterior leaflet. A significant difference between an expert surgeon (n>20 implantations) and beginner surgeon was detected with regard to the duration for successful leaflet grasping (65±73 vs 127±105 s; p=0.02) and the overall duration for implantation (130±86 vs 230±119 s; p=0.002). Gross anatomy did not show major tear of leaflets. There were no device-related technical problems.nnnCONCLUSIONnThe NeoChord DS1000 device for trans-apical beating-heart implantation of neo-chordae to the MV valve showed a high procedural success. A significant difference between an expert and beginner surgeon was detected, which emphasizes the importance of training before introduction of this new technique into clinical practice. Surgical workflow analysis proved to be a valuable tool to assess the performance of this new technique.

Mitral Valve Surgical Procedures in the Elderly

BACKGROUNDnMitral valve (MV) surgical procedures in the elderly are associated with profound operative and long-term mortality. We report our experience and results for MV surgical procedures in the elderly, especially with regard to the influence of comorbidities.nnnMETHODSnOur hospital database was assessed to identify all patients who underwent MV surgical procedures at the age of 70 years and older between 1999 and 2009. The data were retrospectively analyzed.nnnRESULTSnA total of 2,503 patients operated on during this 10-year period were identified. In 97% of patients, mitral regurgitation (MR) was the primary indication for operation, followed by coronary artery disease in 41.6% and aortic valve stenosis in 21.3%. The 30-day mortality rate was 3.1%, and the long-term survival at 5 years was 55.2% (95% confidence interval, 52.3% to 57.5%). Coronary artery bypass grafting was identified to be associated with inferior short-term and long-term survival. Numerous comorbidities significantly influenced long-term survival. The observed mortality was significantly lower than predicted by EuroSCORE (17.2%).nnnCONCLUSIONSnMV operations in the elderly can be performed with a low early mortality and promising long-term survival. However, our large series demonstrates that comorbidities are to be attributed as the real burden for successful treatment of elderly patients undergoing MV procedures.

Video-atlas of transapical aortic valve implantation.

Transapical and transfemoral aortic valve implantation procedures will probably be performed in an ever increasing number of patients with aortic stenosis over the next decades. The following video is an intraoperative film of a transapical aortic valve implantation procedure performed in June 2012 at the Leipzig Heart Center in Germany (Video 1). We have a very large clinical experience with transapical aortic valve procedures at our center, dating back to the first ever performed worldwide at the end of 2004. We have subsequently carried out over 500 transapical and more than 1,000 transfemoral aortic valve implantation procedures. Hopefully the viewer will be able to benefit from our clinical experience and be able to appreciate that such procedures can be performed in a very time-efficient and almost routine manner. Having said this, unexpected complications with rapid and grave consequences can occur at almost any stage of a transcatheter aortic valve procedure. We therefore strongly advise that the operators be aware of such complications before embarking on a transcatheter aortic valve program, and to have planned beforehand what the appropriate response will be for each such complication. n n n nVideo 1 n nTransapical Aortic Valve Implantation n n n nIn the following video, a Sapien XT valve (Edwards Lifesciences; Irvine, CA) was implanted using an Ascendra 2 transapical delivery system. The patient is an 81 year-old male with symptomatic severe aortic stenosis, normal left ventricular function, and previous coronary bypass surgery with patent bypass grafts. The operation is performed by Drs. David Holzhey and Joerg Seeburger. Drs. Thilo Noack and Dennis Merk are filming the procedure, and commentary is supplied by Dr. Michael Borger. We sincerely hope that you find the following video instructive and informative.

Indikationsstellung und Patientenselektion für die kathetergestützte Behandlung der Mitralklappeninsuffizienz

ZusammenfassungDie symptomatische Mitralklappeninsuffizienz (MI) ist die häufigste Herzklappenerkrankung in der westlichen Welt, deren herzchirurgische oder kathetergestützte Therapie einen multidisziplinären Behandlungsansatz benötigt. Die MI wird ätiologisch in eine primäre und eine sekundäre MI unterteilt, welche unterschiedlichen Behandlungsstrategien unterliegen. Die Einführung kathetergestützter Behandlungsverfahren, insbesondere die perkutanen Mitralklappenrekonstruktion mittels MitraClip® (Fa. Abbott Vascular, Santa Clara, CA, USA), haben hierbei zu einer Erweiterung der Behandlungsmöglichkeiten neben der konventionellen Mitralklappenchirurgie geführt. So kann die perkutane Mitralklappenrekonstruktion mittels MitraClip zur Behandlung der primären und sekundären MI unter definierten Voraussetzungen bei inoperablen und Hochrisikopatienten Anwendung finden. Hierbei ist es die Aufgabe des Herzchirurgen, den multidisziplinären Behandlungsprozess aktiv mitzugestalten.Aufgrund der Zunahme der Behandlungszahlen von Patienten mit MI sowie deren Therapie mittels kathetergestützter Techniken hat die Arbeitsgruppe kathetertechnische Herzklappentherapie der Deutschen Gesellschaft für Thorax‑, Herz- und Gefäßchirurgie Empfehlungen für die Indikationsstellung und Patientenauswahl im Rahmen einer interdisziplinären Zusammenarbeit im Herzteam erarbeitet.AbstractSymptomatic mitral regurgitation (MR) is the most common heart valve disease in western countries and cardiac surgery or catheter-based therapy requires axa0multidisciplinary treatment approach. The MR is etiologically subdivided into primary and secondary MR, which are subject to different treatment strategies. The introduction of catheter-based treatment methods, in particular percutaneous mitral valve repair using the MitraClip® system (Abbott Vascular, Santa Clara, CA, USA), has led to an expansion of treatment options alongside conventional mitral valve surgery. Percutaneous mitral valve repair using the MitraClip system can be used for the treatment of primary and secondary MR under defined conditions for inoperable and high-risk patients. It is the task of the cardiac surgeon to actively participate in the multidisciplinary treatment process.Due to the increase in the number of patients with symptomatic MR treated by catheter-based techniques, the working group on catheter-based heart valve therapy of the German Society of Thoracic and Cardiovascular Surgery has developed recommendations for the indications and patient selection within the framework of a multidisciplinary heart team.

COMBINED MITRAL AND TRICUSPID VERSUS ISOLATED MITRAL VALVE EDGE-TO-EDGE REPAIR IN PATIENTS WITH SYMPTOMATIC VALVE REGURGITATION AND HIGH SURGICAL RISK

A growing number of elderly patients with MR are treated by edge-to-edge repair using the MitraClip system, and accumulating evidence suggests that residual TR remains a predictor of adverse outcome in these patients. The clinical benefit of combined edge-to-edge repair of MR plus TR as compared to

Changes in dynamic mitral valve geometry during percutaneous edge–edge mitral valve repair with the MitraClip system

BackgroundThe aim of this study was to quantify the acute dynamic changes of mitral valve (MV) geometry throughout the cardiac cycle—during percutaneous MV repair with the MitraClip system by 3-dimensional transesophageal echocardiography (3D TEE).MethodsThe MV was imaged throughout the cardiac cycle (CC) before and after the MitraClip procedure using 3D TEE in 28 patients (mean age, 77u2009±u20098xa0years) with functional mitral regurgitation (FMR). Dynamic changes in the MV annulus geometry and anatomical MV orifice area (AMVOA) were quantified using a novel semi-automated software.ResultsPercutaneous MV repair decreased anterior–posterior diameter by up to 9% (at 50% of CC; from 34.5 to 31.9xa0mm; pu2009<u20090.001) throughout the CC and increased the diastolic lateral–medial diameter by up to 7% (at 60% of the CC; from 39.7 to 42.3xa0mm; pu2009<u20090.001), whereas the annular circumference and area were not significantly affected. Annulus sphericity index was reduced up to 13% (at 50% of the CC; from 0.89 to 0.78, pu2009<u20090.001). The AMVOA also decreased during systole, the maximum decrease being from 0.6 to 0.2xa0mm2 (at 0% of CC; pu2009=u20090.007), and during diastole the maximum decrease being from 4.6 to 1.6xa0cm2 (at 50% of CC; pu2009<u20090.001).ConclusionsPercutaneous MV repair reduces the MR by an improved coaptation of MV leaflets joint with a simultaneous indirect reduction of anterior–posterior diameter. Further, the MitraClip procedure leads to a reduction of AMVOA of more than 60% during diastole.

Imaging in Cardiac Surgery: Visualizing the Heart

In the physiology of human handling, the hand always follows the eye. Hence, optimal vision is indispensable to perform surgery. With the advent of minimally invasive cardiac surgery, the unobscured direct vision was no longer possible, and therefore endoscopy was introduced to enable it. Advanced endoscopic techniques, as well as catheterbased interventions, demanded improved preoperative planning based on echocardiographic or computed tomographic (CT) data. Therefore, cardiac surgeons had not only to understand and interpret imaging data but also integrate them into their daily practice. Prof. Mohr was one of the pioneers in the field as very early he realized the importance of imaging in the curriculum of a cardiac surgeon, and promoted the acquisition of imaging skills during the residency program in Leipzig. Consequently, several surgeons and anesthesiologists actively developed research projects in the field of image-guided therapy.

Late device embolization after transcatheter mitral valve edge-to-edge repair

Transcatheter mitral edge-to-edge repair is a well-established treatment option for mitral regurgitation (MR) in high-operative risk patients. Device embolization is a potential, however not yet described risk. We herein present two cases of late Mitraclip® embolization.nnSuccessful and uneventful Mitraclip® implantation was performed in a 64 [Pat. A; …

Extracting the Fine Structure of the Left Cardiac Ventricle in 4D CT Data

We propose a pipeline for the segmentation of the left cardiac ventricle (LV) in 4D CT data based on the random walker (RW) algorithm. A segmentation of the LV allows to extract clinical relevant parameters such as ejection fraction (EF) and volume over time (VoT), supporting diagnostic and therapy planning. The presented pipeline works aside approaches incorporating annotated databases, statistical shape modeling or atlas-based segmentation. We have tested our segmentation approach on six clinical 4D CT datasets including different pathologies and typical artifacts and compared the segmentation results to manually segmented slices. We achieve a minimum sensitivity of 86% and specificity of 96%. The resulting EF and VoT is comparable to known reference values and reflects the present pathologies correctly. Additionally, we tested three different routines for thresholding the RW probability maps. An interview with surgical and radiological experts together with high sensitivity scores indicates the superiority of the fixed threshold selection method – especially in the presence of pathologies. The segmentation is also correct near problematic fine structures such as cardiac valves, papillary muscles and the apex of the heart.