Modified Manouguian Technique for Aortic Root Enlargement: A Case Series

Background: Manouguian aortic root enlargement (ARE) has been a standard root enlargement procedure to assist in patients with a small annular size. We describe a modification to the Manouguian ARE similar to Yang et al. This approach could serve as an alternate technique for performing ARE; to date only case reports have defined this approach and no studies have evaluated its efficacy or safety. Methods: A retrospective case series was performed on patients who underwent ARE for surgical aortic valve replacement via the modified Manouguian procedure at a single institution. Thirteen patients were identified between 2015-2021, and all surgeries were performed by a single operator. Data were collected via the Society of Thoracic Surgeons database and chart review. The primary outcome was difference in valve size after the procedure. Results: The most common indication for surgery was aortic stenosis (12, 92%), with the most common etiology being degenerative calcification (7, 54%). Congenital bicuspid or uni-cuspid valves were identified in 5 (38%) patients. The majority (10, 77%) of patients received a mechanical valve. This procedure was successfully performed in all 13 of the patients. Additionally, 13 of the 13 patients (100%) were upsized to a satisfactory valve size based on pre-operative echocardiography sizing. Conclusions: The modified Manouguian aortic enlargement technique can be safely and effectively used as an aortic enlargement procedure in a broad sample of patients.

Considerations and complications with "first principles" dynamic modelling of industrial compressors

Readily available processing hardware and "off-the-shelf" (OTS) simulation software has made "high fidelity" first principles models of both steady and transient states, for both axial and centrifugal industrial compressors, relatively easy to construct. These high-fidelity models are finding their way into "real-time. digital twin" performance monitors, front-end engineering design, and post-design – pre-construction compressor performance evaluation. The compressor models are useful for reliably demonstrating the compressor and – to some degree, based on the complexity of the model – process response to various operating conditions. Once the model is constructed, it is trivial to run a "what-if" analysis of compressor performance to answer questions related to (a) recommendations or validation of the recycle/vent valve size and actuation speed, (b) general piping layout and sizing around the compressor, (c) and hot gas bypass requirements, to name a few. This paper takes a practical approach in discussing the compressor and process parameters necessary for building these dynamic "high-fidelity" industrial-compressor models. We identify compressor inputs and compressor responses that are faithfully modeled by first-principle equations available in the simulation software and those that typically require a compromise between an "ab initio" and data-fitting approximation. We discuss the simulation's tendency to overstate pressure excursions during surge events and understate the compressor operation in the "stonewall" region. We also discuss using the simulator software's compressor-stage enthalpy calculations to predict and quantify the compressor train reverse rotation. We use our broad experience and understanding of the compressor operation and simulation and our experience with the AVEVA™ Dynamic-Simulation "OTS" simulation software as the basis for this discussion.

Discongruence Index: predictor of prosthesis size loss after transcatheter aortic valve replacement

Introduction Prosthesis under-expansion has been associated with higher rates of complications and worse long term outcome after transcatheter aortic valve replacement (TAVR). The objective of the current study was to assess the value of a new “Discongruence index”, to predict the percentage of prosthesis size loss (compared to its nominal size). The “discongruence index” is obtained from the relation between transcatheter valve size and the patient body surface area. Methods A total of 247 consecutive patients with severe aortic stenosis that underwent TAVR with balloon expandable Edwards-Sapiens prosthesis or CoreValve Revalving system at our institution were included. The “Discongruence index” was calculated pre-procedurally as the ratio: selected transcatheter valve size (mm) / body surface area (cm2). Two-dimensional transesophageal echocardiography images were studied in the 120–135° plane after the prosthesis deployment, and the maximum anteroposterior diameter was measured (in millimeters). From this measurement was obtained the percentage of prosthesis size loss (compared to the prosthesis nominal size). Results Mean age was 82±6 years and 102 patients (41.3%) were men. Mean aortic valvular area before TAVR was 0,87±3,8 cm2, (indexed 0,36±0,1 cm2) and the mean aortic gradient 49,1±16,9 mmHg. Mean prosthesis maximum deployment was 18,9±2,7 mm; absolute loss of prosthesis size compared to nominal 6,5±2,8 mm and the percentage loss of prosthesis size 25.1±9,5%. The “Discongruence index” was predictor of the percentage of prosthesis size loss (y = 5,7650 + 1,3010x, p<0,001), see figure. Conclusions The “Discongruence index” is a useful tool to predict the percentage of prosthesis size loss after TAVR. This new index should be taken into consideration in the selection of transcatheter valve sizes to avoid prosthesis under-expansion. FUNDunding Acknowledgement Type of funding sources: None. Figure 1

Infant hydrocephalus: what valve first?

Purpose To review the use of different valve types in infants with hydrocephalus, in doing so, determining whether an optimal valve choice exists for this patient cohort. Methods We conducted (1) a literature review for all studies describing valve types used (programmable vs. non-programmable, valve size, pressure) in infants (≤ 2 years) with hydrocephalus, (2) a review of data from the pivotal BASICS trial for infant patients and (3) a separate, institutional cohort study from Alder Hey Children’s Hospital NHS Foundation Trust. The primary outcome was any revision not due to infection. Results The search identified 19 studies that were included in the review. Most did not identify a superior valve choice between programmable and non-programmable, small compared to ultra-small, and differential pressure compared to flow-regulating valves. Five studies investigated a single-valve type without a comparator group. The BASICS data identified 391 infants, with no statistically significant difference between gravitational and programmable subgroups. The institutional data from our tertiary referral centre did not reveal any significant difference in failure rate between valve subtypes. Conclusion Our review highlights the challenges of valve selection in infant hydrocephalus, reiterating that the concept of an optimal valve choice in this group remains a controversial one. While the infant-hydrocephalic population is at high risk of valve failure, heterogeneity and a lack of direct comparison between valves in the literature limit our ability to draw meaningful conclusions. Data that does exist suggests at present that there is no difference in non-infective failure rate are increasing in number, with the British valve subtypes in infant hydrocephalus, supported by both the randomised trial and institutional data in this study.

Predicting the Ideal Valve Size During Aortic Valve Replacement with Rapid Deployement Bioprosthetic Valves. Is Intraoperative Transesophageal Echocardiogram Reliable?

Objective: To describe experience with using intraoperative Transesophageal Echocardiography to reliably predict the size of the rapid deployment prosthetic valve by measuring the native aortic annulus Methods: Retrospective review of single institution series of patients undergoing Aortic Valve Replacement with Rapid Deployement Bioprosthetic Valves. Included were patients that had their native aortic valve replaced either isolated or as part of any additional procedure. Aortic annulus was measured prior to initiation of the operation using transesophageal echocardiography (TEE). Correlation analysis was conducted between Echocardiographic annular measurements and actual implanted valve sizes. Results: Twenty five patients underwent rapid deployment valve implantation in the aortic position. Of these, 36% of patients had the same size valve as the measured aortic annulus, 48% of patients had a valve implanted that was 1 mm different, and 16% of patients had 2 mm difference. The mean annular size based was 22.4 mm (range: 21-28 mm). The mean valve size implanted was 23.3 mm (range: 21-27 mm). There was no statistically significant difference between the mean annular measurement and the valve size selected (0.9 mm , p = 0.8). Conclusion: TEE can further enhance valve sizing and guidance through a proper and safe deployment. Although evident in our experience, larger scale studies are needed to further elucidate conclusions on the importance of avoiding under-sizing valves.

Geometric changes in aortic root replacement using Freestyle prosthesis

Background The Medtronic Freestyle prosthesis has proven to be a promising recourse for aortic root replacement in various indications. The present study aims to evaluate clinical outcomes and geometric changes of the aorta after Freestyle implantation. Methods Between October 2005 and November 2020, the computed tomography angiography (CTA) data of 32 patients were analyzed in a cohort of 68 patients that underwent aortic root replacement using Freestyle prosthesis. The minimum and maximum diameters and areas of the aortic annulus, aortic root, ascending aorta, and the proximal aortic arch were measured at a plane perpendicular to the long axis of the aorta using 3D multiplanar reconstruction in both the preoperative (n = 32) and postoperative (n = 10) CTAs. Moreover, volumetric changes of the aortic root and ascending aorta were quantified. Results Mean age was 64.6 ± 10.6 years. Indications for surgery using Freestyle prosthesis were combined aortic valve pathologies, aortic aneurysm or dissection, and endocarditis, with concomitant surgery occurring in 28 out of 32 patients. In-hospital mortality was 18.6%. Preoperative diameter and area measurements of the aortic annulus strongly correlated with the implanted valve size (p < 0.001). Bicuspid valve was present in 28.1% of the patients. Diameter and areas of the aortic root decreased after freestyle implantation, resulting in a reduction of the aortic root volume (45.6 ± 26.3 cm3 to 18.7 ± 4.5 cm3, p = 0.029). Volume of the aortic root and the ascending aorta decreased from 137.3 ± 65.2 cm3 to 54.5 ± 21.1 cm3 after Freestyle implantation (p = 0.023). Conclusion Implantation of the Freestyle prosthesis presents excellent results in restoring the aortic geometry. Preoperative CTA measurements are beneficial to the surgical procedure and valve selection and therefore, if available, should be considered in pre-operative planning.

Mitral valve replacement in infants and younger children

Data on mitral valve replacement (MVR) in young children is still limited. Our objective was to evaluate MVR in children below 5 years and identify factors affecting the outcomes. This retrospective study included 29 patients who had MVR from 2002 to 2020. We grouped the patients into two groups according to their age: age ≤ 24 months (n = 18) and > 24 months (n = 11). Primary cardiac diagnoses were Shone complex (n = 7; 24%), isolated congenital mitral valve abnormality (n = 11; 38%), and complete atrioventricular septal defect (n = 3; 10%). The median age was 19 month (25th–75th percentile: 11–32) and 59% were females (n = 17). The hemodynamic lesions were mitral regurgitation in 66%, mitral stenosis in 10%, and combined mitral stenosis and regurgitation in 24% of the patients. St. Jude mitral valve was the most common valve implanted (n = 19, 66%), followed by CarboMedics in 21% of the patients (n = 6). The mitral valve was implanted in the supra-annular position in 6 cases (21%). Preoperative and operative data were comparable between both groups. There was no association between valve size and position with postoperative heart block (P > 0.99, for both). The median follow-up duration was 19.4 months (8.6–102.5). Nine patients had mitral valve reoperation, six had MVR, and three had clot removal from the mitral valve. There was no effect for age group on reoperation (SHR 0.89 (95% CI 0.27–2.87), P = 0.84). Valve size significantly affected reoperation (SHR 0.39 (95% CI 0.18–0.87), P = 0.02). The supra-annular position was associated with an increased risk of reoperation (SHR 3.1 (95% CI 1.003–9.4), P = 0.049). There was no difference in survival according to the age (Log-rank P = 0.57) or valve size (Log-rank P = 0.66). Mitral valve replacement in children is associated with low morbidity and mortality. The risk of reoperation could be affected by the valve size and position rather than the age.

Predicting the Ideal Valve Size During Aortic Valve Replacement with Rapid Deployement Bioprosthetic Valves. Is Intraoperative Transesophageal Echocardiogram Reliable?

Objective: To describe experience with using intraoperative Transesophageal Echocardiography to reliably predict the size of the rapid deployment prosthetic valve by measuring the native aortic annulus Methods: Retrospective review of single institution series of patients undergoing Aortic Valve Replacement with Rapid Deployement Bioprosthetic Valves. Included were patients that had their native aortic valve replaced either isolated or as part of any additional procedure. Aortic annulus was measured prior to initiation of the operation using transesophageal echocardiography (TEE). Correlation analysis was conducted between Echocardiographic annular measurements and actual implanted valve sizes. Results: Twenty five patients underwent rapid deployment valve implantation in the aortic position. Of these, 36% of patients had the same size valve as the measured aortic annulus, 48% of patients had a valve implanted that was 1 mm different, and 16% of patients had 2 mm difference. The mean annular size based was 22.4 mm (range: 21-28 mm). The mean valve size implanted was 23.3 mm (range: 21-27 mm). There was no statistically significant difference between the mean annular measurement and the valve size selected (0.9 mm , p = 0.8). Conclusion: TEE can further enhance valve sizing and guidance through a proper and safe deployment. Although evident in our experience, larger scale studies are needed to further elucidate conclusions on the importance of avoiding under-sizing valves.

Biomechanical Identification of High-Risk Patients Requiring Permanent Pacemaker After Transcatheter Aortic Valve Replacement

BackgroundCardiac conduction disturbance requiring new permanent pacemaker implantation (PPI) is an important complication of TAVR that has been associated with increased mortality. It is extremely challenging to optimize the valve size alone to prevent a complete atrioventricular block (AVB).MethodsIn this study, we randomly took 48 patients who underwent TAVR and had been followed for at least 2 years to assess the risk of AVB. CT images of 48 patients with TAVR were analyzed using three-dimensional (3D) anatomical models of the aortic valve apparatus. The stresses were formulated according to loading force and tissue properties. Support vector regression (SVR) was used to model the relationship between AVB risk and biomechanical stresses. To avoid AVB, overlapping regions on the prosthetic valve where AV bundle passes will be removed as cylindrical sector with the angle θ. Thus, the optimization of the valve shape will be predicted with the joint optimization of the θ and valve size R.ResultsThe average AVB risk prediction accuracy was 83.33% in the range from 0.8–0.85 with 95% CI for all cases; specifically, 85.71% for Group A (no AVB), and 80.0% for Group B (undergoing AVB after the TAVR).ConclusionsThis model can estimate the optimal valve size and shape to avoid the risk of AVB after TAVR. This optimization may eliminate the excessive stresses to keep the normal function of both AV bundle and valve leaflets, leading to a favorable clinical outcome. The combination of biomechanical properties and machine learning method substantially improved prediction of surgical results.