Predictors of Conduction Disturbances after Transcatheter Aortic Valve Implantation with Balloon-expandable Valve for Bicuspid Aortic Valve Stenosis

Objective: The implantation depth and membranous septum (MS) length are established as the predictors of new-onset conduction disturbance (CD) after transcatheter aortic valve replacement (TAVR) for tricuspid aortic valve (TAV) stenosis. However, little is known about the predictors with bicuspid aortic valve (BAV). This study investigated the role of MS length and implantation depth in predicting CD following TAVR with a balloon-expandable valve in patients with BAV. Methods and results: This retrospective study analyzed 169 patients who underwent TAVR for BAV with balloon-expandable valve, and TAV cohort was established as a control group using propensity score (PS) matching. The primary endpoint was in-hospital new-onset CD (new-onset left bundle branch block or new permanent pacemaker implantation). New-onset CD developed in 37 patients (21.9%). Multivariate analysis revealed severe LVOT calcification (Odds ratio [OR]: 5.83, 95% confidence interval [CI]: 1.08 – 31.5, p = 0.0407) and implantation depth – MS length (OR: 1.30, 95% CI: 1.12 – 1.51, p = 0.0005) as the predictors of new-onset CD within BAV cohort. The matched comparison between BAV and TAV groups showed similar MS length (3.0 vs 3.2mm, p = 0.5307), but valves were implanted deeper in BAV than TAV group (3.9 vs 3.0mm, p < .0001). New-onset CD was more frequent in patients having BAV (22.3% vs 13.9%, p = 0.0458). Conclusion: The implantation depth - MS length, and severe LVOT calcification predicted new-onset CD following TAVR in BAV with balloon-expandable valve. High implantation technique could be considered to avoid new-onset CD in BAV anatomy.

The Predictors of Conduction Disturbances Following Transcatheter Aortic Valve Replacement in Patients With Bicuspid Aortic Valve: A Multicenter Study

Objective: To evaluate the predictors of new-onset conduction disturbances in bicuspid aortic valve patients using self-expanding valve and identify modifiable technical factors.Background: New-onset conduction disturbances (NOCDs), including complete left bundle branch block and high-grade atrioventricular block, remain the most common complication after transcatheter aortic valve replacement (TAVR).Methods: A total of 209 consecutive bicuspid patients who underwent self-expanding TAVR in 5 centers in China were enrolled from February 2016 to September 2020. The optimal cut-offs in this study were generated from receiver operator characteristic curve analyses. The infra-annular and coronal membranous septum (MS) length was measured in preoperative computed tomography. MSID was calculated by subtracting implantation depth measure on postoperative computed tomography from infra-annular MS or coronal MS length.Results: Forty-two (20.1%) patients developed complete left bundle branch block and 21 (10.0%) patients developed high-grade atrioventricular block after TAVR, while 61 (29.2%) patients developed NOCDs. Coronal MS &lt;4.9 mm (OR: 3.08, 95% CI: 1.63–5.82, p = 0.001) or infra-annular MS &lt;3.7 mm (OR: 2.18, 95% CI: 1.04–4.56, p = 0.038) and left ventricular outflow tract perimeter &lt;66.8 mm (OR: 4.95 95% CI: 1.59–15.45, p = 0.006) were powerful predictors of NOCDs. The multivariate model including age &gt;73 years (OR: 2.26, 95% CI: 1.17–4.36, p = 0.015), Δcoronal MSID &lt;1.8 mm (OR: 7.87, 95% CI: 2.84–21.77, p &lt; 0.001) and prosthesis oversizing ratio on left ventricular outflow tract &gt;3.2% (OR: 3.42, 95% CI: 1.74–6.72, p &lt; 0.001) showed best predictive value of NOCDs, with c-statistic = 0.768 (95% CI: 0.699–0.837, p &lt; 0.001). The incidence of NOCDs was much lower (7.5 vs. 55.2%, p &lt; 0.001) in patients without Δcoronal MSID &lt;1.8 mm and prosthesis oversizing ratio on left ventricular outflow tract &gt;3.2% compared with patients who had these two risk factors.Conclusion: The risk of NOCDs in bicuspid aortic stenosis patients could be evaluated based on MS length and prosthesis oversizing ratio. Implantation depth guided by MS length and reducing the oversizing ratio might be a feasible strategy for heavily calcified bicuspid patients with short MS.

Prosthesis position and its influence on complications after transcatheter aortic valve implantation with self-expanding valves

Background/Introduction Prior studies in patients with transcatheter aortic valve implantation (TAVI) demonstrated an influence of transcatheter heart valve (THV) position on the occurrence of new conductions disturbances (CD) and paravalvular leakage (PVL) post TAVI in balloon-expandable valves (BEV). Purpose Purpose of this study was to investigate the THV position and its influence on the occurrence of CD and PVL in self-expanding valves (SEV). Methods We performed fusion imaging of pre- and post-procedural computed tomography angiography in 104 TAVI-patients (all with Evolut R) to receive a 3-D reconstruction of the THV within the native annulus region. The THV length below the native annulus was measured for assessment of implantation depth. Electrocardiograms pre-discharge were assessed for conduction disturbances (CD), PVL was determined in transthoracic echocardiography. Results The mean implantation depth of the THV in the whole cohort was 4.3±3.0 mm. Using the best cut-off of &gt;4 mm in receiver operating characteristic curve analysis (sensitivity 83.3%, specificity 60.0%) patients with lower THV position developed more new CD after TAVI (68.2 vs. 23.7%, P&lt;0.001). A deep THV position was identified as the only predictor for new CD after TAVI (odds ratio [CI]: 1.312 [1.119–1.539], P=0.001). The implantation depth showed no influence on the grade of PVL (r=0.052, P=0.598). Conclusions In patients with TAVI using the Evolut R SEV, a lower THV positioning (&gt;4 mm length below annulus) was a predictor for new conduction disturbances. In contrast, prosthesis position was not associated with the extent of PVL. FUNDunding Acknowledgement Type of funding sources: None.

Paravalvular leakage of transcatheter aortic valve replacements depending on aortic annulus calcification

Paravalvular leakage (PVL) has a crucial impact on clinical outcomes of transcateheter aortic valve replacements (TAVR), especially the mortality increases dramatically with high-grade PVL. Furthermore, the calcification of the aortic annulus has a decisive influence on the PVL of TAVR. Therefore, we developed a technical model of a calcified aortic annulus and used it for the investigation of PVL in steady-state back-flow conditions. We investigated an Evolut PRO (Medtronic, Minneapolis, MN, USA), implanted the TAVR at different depths in the aortic annulus model ranging between 0 mm and -6 mm and characterized PVL in steady-state retrograde flow from 0 mmHg up to a maximum achievable pressure. The used test bench and detailed test method was described in previous studies. The aortic annulus model exhibits three elevations symmetrically distributed around the circumference. Depending on the degree of calcification the elevations reached 1 mm to 3 mm into the lumen. For the Evolut PRO bioprosthesis, a decreasing PVL was measured with increasing implantation depth. At an implantation depth of 0 mm (inflow of TAVR and annulus model at same height) maximum PVL was measured. Minimum PVL was measured at a height of -6 mm. Furthermore, even a small calcification of 1 mm led to a large increase in PVL. This trend continued with increasing height of the calcification. The maximum regurgitation of (2,025.21 ± 12.47) ml (n = 3 measurements) was measured at a pressure of 6 mmHg in the annulus model with 3 mm calcification. A test method to quantify PVL depending on annular calcification was successfully developed. Additionally, the influence of implantation depth on PVL was characterized. Due to the technical operating principle of the test bench, only a limited increase in pressure was possible when large PVL occurred. In this respect, the test bench must be optimized in the future.

Influence of Implantation Depth on the Performance of Intracortical Probe Recording Sites

Microelectrode arrays (MEAs) enable the recording of electrical activity from cortical neurons which has implications for basic neuroscience and neuroprosthetic applications. The design space for MEA technology is extremely wide where devices may vary with respect to the number of monolithic shanks as well as placement of microelectrode sites. In the present study, we examine the differences in recording ability between two different MEA configurations: single shank (SS) and multi-shank (MS), both of which consist of 16 recording sites implanted in the rat motor cortex. We observed a significant difference in the proportion of active microelectrode sites over the 8-week indwelling period, in which SS devices exhibited a consistent ability to record activity, in contrast to the MS arrays which showed a marked decrease in activity within 2 weeks post-implantation. Furthermore, this difference was revealed to be dependent on the depth at which the microelectrode sites were located and may be mediated by anatomical heterogeneity, as well as the distribution of inhibitory neurons within the cortical layers. Our results indicate that the implantation depth of microelectrodes within the cortex needs to be considered relative to the chronic performance characterization.

Inductive Power Transfer Link at 13.56 MHz for Leadless Cardiac Pacemakers

Inductive power links are most viable for the long-term powering of cardiac pacemakers. Designing an inductive power link without surpassing the specific absorption rate (SAR) for modern leadless cardiac pacemakers (LCPs) remains a challenging task because of its size and implantation depth. The inductive power link employed in the conventional works is either designed at a high frequency or based on the size, shape, weight, and implantation depth of conventional cardiac pacemakers. Here, a 3-coil inductive power transfer link with a circular transmitter coil and solenoidal receiver coil is designed at 13.56 MHz to provide uninterrupted power to the modern LCPs. Considering the food and drug administration approved term for implant size of modern LCP, the receiver coil is designed with 6 mm diameter and 6.5 mm length. The performance of the link has been verified through simulations and measurements under perfect alignment, lateral and/or angular misalignments, and distance variation between the coils. At a 50 mm horizontal distance between transmitter and receiver coils, the transmission coefficient is −30.9 dB. The maximum simulated average SAR at heterogeneous phantom is 0.30 W/kg, which is lower than the limit set by the Federal Communications Commission for radiation threshold exposure. Experiments conducted on pork’s heart verified the reliability of the simulated results. At a 50 mm distance between the coils, the measured transmission coefficient is −34 dB, and at an input power of 1 W, the power delivered to the load is 0.7 mW.

Factors associated with a high or low implantation of self-expanding devices in TAVR

Objectives Optimizing valve implantation depth (ID) plays a crucial role in minimizing conduction disturbances and achieving optimal functional integrity. Until now, the impact of intraprocedural fast (FP) or rapid ventricular pacing (RP) on the implantation depth has not been investigated. Therefore, we aimed to (1) evaluate the impact of different pacing maneuvers on ID, and (2) identify the independent predictors of deep ID. Methods 473 TAVR patients with newer-generation self-expanding devices were retrospectively enrolled and one-to-one propensity-score-matching was performed, resulting in a matching of 189 FP and RP patients in each cohort. The final ID was analyzed, and the underlying functional, anatomical, and procedural conditions were evaluated by univariate and multivariate analysis. Results The highest ID was reached under RP in severe aortic valve calcification and valve size 26 mm. Multivariate analysis identified left ventricular outflow (LVOT) calcification [OR 0.50 (0.31–0.81) p = 0.005*], a “flare” aortic root [OR 0.42 (0.25–0.71), p = 0.001*], and RP (OR 0.49 [0.30–0.79], p = 0.004*) as independent highly preventable predictors of a deep ID. In a model of protective factors, ID was significantly reduced with the number of protective criteria (0–2 criteria: − 5.7 mm ± 2.6 vs. 3–4 criteria − 4.3 mm ± 2.0; p < 0.0001*). Conclusion Data from this retrospective analysis indicate that RP is an independent predictor to reach a higher implantation depth using self-expanding devices. Randomized studies should prove for validation compared to fast and non-pacing maneuvers during valve delivery and their impact on implantation depth. Trail registration Clinical Trial registration: NCT01805739. Graphic abstract Study design: Evaluation of the impact of different pacing maneuvers (fast ventricular pacing—FP vs. rapid ventricular pacing—RP) on implantation depth (ID). After one-to-one-propensity-score-matching, independent protective and risk factors for a very deep ID beneath 6 mm toward the LVOT (< − 6 mm) were identified. Stent frame pictures as a courtesy by Medtronic®. AVC aortic valve calcification.