Impact of mitral regurgitation on clinical outcomes of patients with low-ejection fraction, low-gradient severe aortic stenosis undergoing transcatheter aortic valve implantation.

BACKGROUND Up to 1 in 6 patients undergoing transcatheter aortic valve implantation (TAVI) present with low-ejection fraction, low-gradient (LEF-LG) severe aortic stenosis and concomitant relevant mitral regurgitation (MR) is present in 30% to 55% of these patients. The effect of MR on clinical outcomes of LEF-LG patients undergoing TAVI is unknown. METHODS AND RESULTS Of 606 consecutive patients undergoing TAVI, 113 (18.7%) patients with LEF-LG severe aortic stenosis (mean gradient ≤40 mm Hg, aortic valve area <1.0 cm(2), left ventricular ejection fraction <50%) were analyzed. LEF-LG patients were dichotomized into ≤mild MR (n=52) and ≥moderate MR (n=61). Primary end point was all-cause mortality at 1 year. No differences in mortality were observed at 30 days (P=0.76). At 1 year, LEF-LG patients with ≥moderate MR had an adjusted 3-fold higher rate of all-cause mortality (11.5% versus 38.1%; adjusted hazard ratio, 3.27 [95% confidence interval, 1.31-8.15]; P=0.011), as compared with LEF-LG patients with ≤mild MR. Mortality was mainly driven by cardiac death (adjusted hazard ratio, 4.62; P=0.005). As compared with LEF-LG patients with ≥moderate MR assigned to medical therapy, LEF-LG patients with ≥moderate MR undergoing TAVI had significantly lower all-cause mortality (hazard ratio, 0.38; 95% confidence interval, 0.019-0.75) at 1 year. CONCLUSIONS Moderate or severe MR is a strong independent predictor of late mortality in LEF-LG patients undergoing TAVI. However, LEF-LG patients assigned to medical therapy have a dismal prognosis independent of MR severity suggesting that TAVI should not be withheld from symptomatic patients with LEF-LG severe aortic stenosis even in the presence of moderate or severe MR.

Transcatheter aortic valve implantation in a lung transplant recipient.

Transcatheter aortic valve implantation is a feasible therapeutic option for selected patients with severe aortic stenosis and high or prohibitive risk for standard surgery. Lung transplant recipients are often considered high-risk patients for heart surgery because of their specific transplant-associated characteristics and comorbidities. We report a case of successful transfemoral transcatheter aortic valve replacement in a lung transplant recipient with a symptomatic severe aortic stenosis, severe left ventricular dysfunction, and end-stage renal failure 9 years after bilateral lung transplantation.

The pre- and post-somatic segments of the human type I spiral ganglion neurons--structural and functional considerations related to cochlear implantation.

Human auditory nerve afferents consist of two separate systems; one is represented by the large type I cells innervating the inner hair cells and the other one by the small type II cells innervating the outer hair cells. Type I spiral ganglion neurons (SGNs) constitute 96% of the afferent nerve population and, in contrast to other mammals, their soma and pre- and post-somatic segments are unmyelinated. Type II nerve soma and fibers are unmyelinated. Histopathology and clinical experience imply that human SGNs can persist electrically excitable without dendrites, thus lacking connection to the organ of Corti. The biological background to this phenomenon remains elusive. We analyzed the pre- and post-somatic segments of the type I human SGNs using immunohistochemistry and transmission electron microscopy (TEM) in normal and pathological conditions. These segments were found surrounded by non-myelinated Schwann cells (NMSCs) showing strong intracellular expression of laminin-β2/collagen IV. These cells also bordered the perikaryal entry zone and disclosed surface rugosities outlined by a folded basement membrane (BM) expressing laminin-β2 and collagen IV. It is presumed that human large SGNs are demarcated by three cell categories: (a) myelinated Schwann cells, (b) NMSCs and (c) satellite glial cells (SGCs). Their BMs express laminin-β2/collagen IV and reaches the BM of the sensory epithelium at the habenula perforata. We speculate that the NMSCs protect SGNs from further degeneration following dendrite loss. It may give further explanation why SGNs can persist as electrically excitable monopolar cells even after long-time deafness, a blessing for the deaf treated with cochlear implantation.

The Self-Expanding Symetis Acurate Does Not Increase Cerebral Microembolic Load When Compared to the Balloon-Expandable Edwards Sapien Prosthesis: A Transcranial Doppler Study in Patients Undergoing Transapical Aortic Valve Implantation

Objectives The aim of this study was to quantify potential differences in count, frequency and pattern of high-intensity transient signals (HITS) during transapical transcatheter aortic valve implantation (TA-TAVI), by comparing the Symetis Acurate TA (SA) with the balloon-expandable Edwards Sapien XT (ES) system. Background Recently, the Symetis Acurate TA revalving system has been introduced for TA-TAVI. The Symetis Acurate TA aortic bioprosthesis is self-expanding and is deployed by a specific two-step implantation technique. Whether this novel method increases the load of intraprocedural emboli, detected by transcranial Doppler ultrasound (TCD) as HITS, or not is not clear. Methods Twenty-two patients (n = 11 in each study arm, median logistic EuroScore 20%, median STS score 7%) displayed continuous TCD signals of good quality throughout the entire TA-TAVI procedure and were included in the final analysis. Data are presented as median with interquartile ranges. Results No significant differences were detected in total procedural or interval-related HITS load (SA: 303 [200; 594], ES: 499 [285; 941]; p = 0.16). With both devices, HITS peaked during prosthesis deployment (PD), whereas significantly fewer HITS occurred during instrumentation (SA: p = 0.002; ES: <0.001) or post-implantation PI (SA: p = 0.007; ES: <0.001). PD-associated HITS amounted to almost half of the total HITS load. One patient suffered new disabling stroke at 30 days. Thirty-day mortality amounted to 13.6% (3 of 22 patients). Conclusions Simplified transapical delivery using the self-expanding SA device does not increase HITS, despite of a two-step deployment technique with more interactions with the native aortic valve, when compared to the balloon-expandable ES valve. The similarity in HITS count, frequency and pattern with the two systems suggests a common mechanism for the release of cerebral microemboli.

Impact of local endothelial shear stress on neointima and plaque following stent implantation in patients with ST-elevation myocardial infarction: A subgroup-analysis of the COMFORTABLE AMI-IBIS 4 trial.

BACKGROUND Numerous studies have demonstrated an association between endothelial shear stress (ESS) and neointimal formation after stent implantation. However, the role of ESS on the composition of neointima and underlying plaque remains unclear. METHODS Patients recruited in the Comfortable AMI-IBIS 4 study implanted with bare metal stents (BMS) or biolimus eluting stents (BES) that had biplane coronary angiography at 13month follow-up were included in the analysis. The intravascular ultrasound virtual-histology (IVUS-VH) and the angiographic data were used to reconstruct the luminal surface, and the stent in the stented segments. Blood flow simulation was performed in the stent surface, which was assumed to represent the luminal surface at baseline, to assess the association between ESS and neointima thickness. The predominant ESS was estimated in 3-mm segments and was correlated with the amount of neointima, neointimal tissue composition, and with the changes in the underlying plaque burden and composition. RESULTS Forty three patients (18 implanted with BMS and 25 with BES) were studied. In both stent groups negative correlations were noted between ESS and neointima thickness in BMS (P<0.001) and BES (P=0.002). In BMS there was a negative correlation between predominant ESS and the percentage of the neointimal necrotic core component (P=0.015). In BES group, the limited neointima formation did not allow evaluation of the effect of ESS on its tissue characteristics. ESS did not affect vessel wall remodeling and the plaque burden and composition behind BMS (P>0.10) and BES (P>0.45). CONCLUSIONS ESS determines neointimal formation in both BMS and BES and affects the composition of the neointima in BMS. Conversely, ESS does not impact the plaque behind struts irrespective of stent type throughout 13months of follow-up.

Effect of Pulmonary Hypertension Hemodynamic Presentation on Clinical Outcomes in Patients With Severe Symptomatic Aortic Valve Stenosis Undergoing Transcatheter Aortic Valve Implantation: Insights From the New Proposed Pulmonary Hypertension Classification.

BACKGROUND Pulmonary hypertension (PH) frequently coexists with severe aortic stenosis, and PH severity has been shown to predict outcomes after transcatheter aortic valve implantation (TAVI). The effect of PH hemodynamic presentation on clinical outcomes after TAVI is unknown. METHODS AND RESULTS Of 606 consecutive patients undergoing TAVI, 433 (71.4%) patients with severe aortic stenosis and a preprocedural right heart catheterization were assessed. Patients were dichotomized according to whether PH was present (mean pulmonary artery pressure, ≥25 mm Hg; n=325) or not (n=108). Patients with PH were further dichotomized by left ventricular end-diastolic pressure into postcapillary (left ventricular end-diastolic pressure, >15 mm Hg; n=269) and precapillary groups (left ventricular end-diastolic pressure, ≤15 mm Hg; n=56). Finally, patients with postcapillary PH were divided into isolated (n=220) and combined (n=49) subgroups according to whether the diastolic pressure difference (diastolic pulmonary artery pressure-left ventricular end-diastolic pressure) was normal (<7 mm Hg) or elevated (≥7 mm Hg). Primary end point was mortality at 1 year. PH was present in 325 of 433 (75%) patients and was predominantly postcapillary (n=269/325; 82%). Compared with baseline, systolic pulmonary artery pressure immediately improved after TAVI in patients with postcapillary combined (57.8±14.1 versus 50.4±17.3 mm Hg; P=0.015) but not in those with precapillary (49.0±12.6 versus 51.6±14.3; P=0.36). When compared with no PH, a higher 1-year mortality rate was observed in both precapillary (hazard ratio, 2.30; 95% confidence interval, 1.02-5.22; P=0.046) and combined (hazard ratio, 3.15; 95% confidence interval, 1.43-6.93; P=0.004) but not isolated PH patients (P=0.11). After adjustment, combined PH remained a strong predictor of 1-year mortality after TAVI (hazard ratio, 3.28; P=0.005). CONCLUSIONS Invasive stratification of PH according to hemodynamic presentation predicts acute response to treatment and 1-year mortality after TAVI.

Temperature Prediction Model for Bone Drilling Based on Density Distribution and In Vivo Experiments for Minimally Invasive Robotic Cochlear Implantation

Surgical robots have been proposed ex vivo to drill precise holes in the temporal bone for minimally invasive cochlear implantation. The main risk of the procedure is damage of the facial nerve due to mechanical interaction or due to temperature elevation during the drilling process. To evaluate the thermal risk of the drilling process, a simplified model is proposed which aims to enable an assessment of risk posed to the facial nerve for a given set of constant process parameters for different mastoid bone densities. The model uses the bone density distribution along the drilling trajectory in the mastoid bone to calculate a time dependent heat production function at the tip of the drill bit. Using a time dependent moving point source Green's function, the heat equation can be solved at a certain point in space so that the resulting temperatures can be calculated over time. The model was calibrated and initially verified with in vivo temperature data. The data was collected in minimally invasive robotic drilling of 12 holes in four different sheep. The sheep were anesthetized and the temperature elevations were measured with a thermocouple which was inserted in a previously drilled hole next to the planned drilling trajectory. Bone density distributions were extracted from pre-operative CT data by averaging Hounsfield values over the drill bit diameter. Post-operative [Formula: see text]CT data was used to verify the drilling accuracy of the trajectories. The comparison of measured and calculated temperatures shows a very good match for both heating and cooling phases. The average prediction error of the maximum temperature was less than 0.7 °C and the average root mean square error was approximately 0.5 °C. To analyze potential thermal damage, the model was used to calculate temperature profiles and cumulative equivalent minutes at 43 °C at a minimal distance to the facial nerve. For the selected drilling parameters, temperature elevation profiles and cumulative equivalent minutes suggest that thermal elevation of this minimally invasive cochlear implantation surgery may pose a risk to the facial nerve, especially in sclerotic or high density mastoid bones. Optimized drilling parameters need to be evaluated and the model could be used for future risk evaluation.