Philipp Kiefer

Crimping May Affect the Durability of Transcatheter Valves: An Experimental Analysis

BACKGROUND Transcatheter aortic valve implantation has gained widespread acceptance to treat elderly high-risk patients with aortic stenosis. We used a subcutaneous rat model to evaluate whether crimping may affect valve long-term durability. METHODS Standard Sapien transcatheter valves (Edwards Lifesciences, Irvine, CA) were crimped for different durations (1 hour, 1 day, 1 month) and uncrimped, and leaflet pieces as well as control tissue (Perimount Magna, Edwards) were then implanted subcutaneously in 15 male weanling Sprague-Dawley rats for 12 weeks. Grade of calcification was measured by freeze-dried mass and van Kossa staining. Histologic and electron microscopic examination were performed to investigate potential leaflet-fragmentation caused by crimping. RESULTS There were no differences in calcification among the groups. The calcium carbonate concentrations in all samples ranged from 0.1 to 100 mg/g dry weight. Leaflet morphology, however, differed from no fragmentation (control group) to highly fragmented tissue (1-month crimped). These differences reached statistical significance between crimped and non-crimped leaflets (p<0.003). CONCLUSIONS Transcatheter valve crimping does not necessarily affect leaflet calcification. However, the structural changes of the leaflets that were caused by crimping may have clinical significance. Duration of crimping should be as short as possible, and very tight crimping to small diameters should be avoided.

New concepts for mitral valve imaging

The high complexity of the mitral valve (MV) anatomy and function is not yet fully understood. Studying especially the dynamic movement and interaction of MV components to describe MV physiology during the cardiac cycle remains a challenge. Imaging is the key to assessing details of MV disease and to studying the lesion and dysfunction of MV according to Carpentier. With the advances of computational geometrical and biomechanical MV models, improved quantification and characterization of the MV has been realized. Geometrical models can be divided into rigid and dynamic models. Both models are based on reconstruction techniques of echocardiographic or computed tomographic data sets. They allow detailed analysis of MV morphology and dynamics throughout the cardiac cycle. Biomechanical models aim to simulate the biomechanics of MV to allow for examination and analysis of the MV structure with blood flow. Two categories of biomechanical MV models can be distinguished: structural models and fluid-structure interaction (FSI) models. The complex structure and dynamics of MV apparatus throughout the cardiac cycle can be analyzed with different types of computational models. These represent substantial progress in the diagnosis of structural heart disease since MV morphology and dynamics can be studied in unprecedented detail. It is conceivable that MV modeling will contribute significantly to the understanding of the MV.

Mitral Valve Surgical Procedures in the Elderly

BACKGROUND Mitral 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. METHODS Our 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. RESULTS A 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%). CONCLUSIONS MV 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.

Four-dimensional modelling of the mitral valve by real-time 3D transoesophageal echocardiography: proof of concept

OBJECTIVES The complexity of the mitral valve (MV) anatomy and function is not yet fully understood. Assessing the dynamic movement and interaction of MV components to define MV physiology during the complete cardiac cycle remains a challenge. We herein describe a novel semi-automated 4D MV model. METHODS The model applies quantitative analysis of the MV over a complete cardiac cycle based on real-time 3D transoesophageal echocardiography (RT3DE) data. RT3DE data of MVs were acquired for 18 patients. The MV annulus and leaflets were semi-automatically reconstructed. Dimensions of the mitral annulus (anteroposterior and anterolateral-posteromedial diameter, annular circumference, annular area) and leaflets (MV orifice area, intercommissural distance) were acquired. Variability and reproducibility (intraclass correlation coefficient, ICC) for interobserver and intraobserver comparison were quantified at 4 time points during the cardiac cycle (mid-systole, end-systole, mid-diastole and end-diastole). RESULTS Mitral annular dimensions provided highly reliable and reproducible measurements throughout the cardiac cycle for interobserver (variability range, 0.5-1.5%; ICC range, 0.895-0.987) and intraobserver (variability range, 0.5-1.6%; ICC range, 0.827-0.980) comparison, respectively. MV leaflet parameters showed a high reliability in the diastolic phase (variability range, 0.6-9.1%; ICC range, 0.750-0.986), whereas MV leaflet dimensions showed a high variability and lower correlation in the systolic phase (variability range, 0.6-22.4%; ICC range, 0.446-0.915) compared with the diastolic phase. CONCLUSIONS This 4D model provides detailed morphological reconstruction as well as sophisticated quantification of the complex MV structure and dynamics throughout the cardiac cycle with a precision not yet described.

The role of the heart team in complicated transcatheter aortic valve implantation: a 7-year single-centre experience

OBJECTIVES European guidelines recommend to perform transcatheter aortic valve implantation (TAVI) within a multidisciplinary heart team. However, there is a strong drive--despite existing guidelines--to perform TAVI outside of specialized centres. The aim of this study was to clarify the necessity of on-site cardiac surgery by providing a clear insight into the complications during/after TAVI that needed surgical management. METHODS A total of 2287 (1523 transfemoral, 752 transapical and 12 transaortic) patients, with a mean age of 84.5 ± 5.3 years, and a mean log EuroSCORE of 21.7 ± 16.3, of which 205 were female (84%), underwent TAVI since February 2006 at our institution. All procedure-related complications that required surgical interventions, whether immediate or delayed but within the initial hospital stay, were recorded and retrospectively analysed. RESULTS Out of this cohort, 245 (10.7%) patients required surgical treatment due to major complications. A total of 42 patients (1.8%) underwent conversion to full sternotomy and 27 (1.2%) were dependent on the short-term use of the heart-lung machine. Vascular complications with surgical intervention were seen in 85 patients (3.7%), 54 patients (2.4%) had to have a rethoracotomy within their initial stay and 15 (0.7%) required a cardiac reoperation. CONCLUSIONS Severe complications during TAVI that can only be resolved surgically will continue to occur. Therefore, each TAVI procedure should be conducted or accompanied by a cardiac surgeon and an experienced team within a specialized centre.

Reno-protective effects of epigallocatechingallate in a small piglet model of extracorporeal circulation

Cardiopulmonary bypass still often is a necessary tool in cardiac surgery in particular in the correction of congenital heart defects in small infants. Nevertheless, among the complications linked to extracorporeal circulation (ECC) with cardiopulmonary bypass (CPB) in both infants and adults one of the most serious problems is renal impairment. Since this might be caused by ischemia/reperfusion injury and accumulation of free radicals, we used (-)-epigallocatechin-3-gallate (EGCG), a derivate from green tea, which is known to possess antioxidant, antiapoptotic and NO-scavenging properties in order to find out whether EGCG may protect the kidney. 23 four-week-old Angler Sattelschwein-piglets (8-15 kg) were divided into three groups: control-group (n=7), ECC-group (n=10), EGCG-group (n=6). The ECC- and EGCG-group were thoracotomized and underwent CPB for 120 min followed by a 90-min recovery-time. The EGCG-group received 10 mg/kg EGCG before and after CPB. Histology revealed that CPB led to widening of Bowmans capsule, and to vacuolization of proximal tubular cells (p<0.05) which could be prevented by EGCG (p<0.05). Using immunohistology, we found significant nuclear translocation of hypoxia-inducible-factor-1-alpha (HIF-1-alpha) and increased nitrotyrosine formation in the ECC-group. Both were significantly (p<0.05) inhibited by EGCG. ECC-induced loss of energy-rich phosphates was prevented by EGCG. In blood samples we found that CPB resulted in increases in creatinine and urea (in serum) and led to loss of total protein (p<0.05), which all was not present in EGCG-treated animals. We conclude that CPB causes damage in the kidney which can be attenuated by EGCG.

Significant acceleration of 2D-3D registration-based fusion of ultrasound and x-ray images by mesh-based DRR rendering

For transcatheter-based minimally invasive procedures in structural heart disease ultrasound and X-ray are the two enabling imaging modalities. A live fusion of both real-time modalities can potentially improve the workflow and the catheter navigation by combining the excellent instrument imaging of X-ray with the high-quality soft tissue imaging of ultrasound. A recently published approach to fuse X-ray fluoroscopy with trans-esophageal echo (TEE) registers the ultrasound probe to X-ray images by a 2D-3D registration method which inherently provides a registration of ultrasound images to X-ray images. In this paper, we significantly accelerate the 2D-3D registration method in this context. The main novelty is to generate the projection images (DRR) of the 3D object not via volume ray-casting but instead via a fast rendering of triangular meshes. This is possible, because in the setting for TEE/X-ray fusion the 3D geometry of the ultrasound probe is known in advance and their main components can be described by triangular meshes. We show that the new approach can achieve a speedup factor up to 65 and does not affect the registration accuracy when used in conjunction with the gradient correlation similarity measure. The improvement is independent of the underlying registration optimizer. Based on the results, a TEE/X-ray fusion could be performed with a higher frame rate and a shorter time lag towards real-time registration performance. The approach could potentially accelerate other applications of 2D-3D registrations, e.g. the registration of implant models with X-ray images.

Transapical neochord implantation

The neo-chord procedure was introduced to facilitate chordal replacement for mitral valve repair using a transapical beating heart off-pump approach. This tutorial describes the concept, the technique, the operative approach, and the procedure in a step-by-step manner.

Epigallocatechin gallate attenuates cardiopulmonary bypass–associated lung injury

BACKGROUND Lung dysfunction constitutes a severe complication after major cardiac surgery with cardiopulmonary bypass (CPB), substantially contributing to postoperative morbidity and mortality. The current possibilities of preventive and therapeutic interventions, however, remain insufficient. We, therefore, investigated the effects of intraoperative application of the antioxidant and anti-inflammatory green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) on CPB-associated lung injury. MATERIALS AND METHODS Thirty piglets (8-15 kg) were divided into four groups: sham-operated and saline-treated control group (n = 7); sham-operated and EGCG-treated control group (EGCG-control group; n = 7); CPB group (n = 10); and CPB + EGCG group (n = 6). The CPB groups underwent 120 min of CPB followed by 90 min of recovery time. In the CPB + EGCG group, EGCG (10 mg/kg body weight) was administered intravenously before and after CPB. Hemodynamic monitoring, blood gas analysis, hematoxylin-eosin staining, and immunohistochemistry of lung tissue were performed. RESULTS Histologic examination revealed thickening of the alveolar wall and enhanced alveolar neutrophil infiltration in the CPB group (P < 0.05) compared with those in the control group, which was prevented by EGCG (P < 0.05). In the CPB group, higher formation of poly(ADP-ribose) and nuclear translocation of apoptosis-inducing factor was detected in comparison with those in the control group (P < 0.001), which were both reduced in the CPB + EGCG group (P < 0.001). Compared with the control group, the EGCG-control group showed thickening of the alveolar wall and increased neutrophil infiltration (P < 0.05). CONCLUSIONS CPB leads to lung edema, pulmonary neutrophil infiltration, and presumably initiation of poly(ADP-ribose) polymerase-dependent cell death signaling in the lung. EGCG appears to attenuate CPB-associated lung injury, suggesting that this may provide a novel pharmacologic approach.

Early experience of the trialign system for catheter-based treatment of severe tricuspid regurgitation

Compassionate treatment of severe tricuspid regurgitation (TR) using the transcatheter Trialign system has previously been reported. Here we report our early experience of this innovative technology. A 77-year-old frail woman presented with 4+ TR and chronic, intractable right ventricular failure. Given the very high operative risk, the institutional heart team decided to …