Conventional vs. Sutureless Aortic Valve Bioprosthesis: Is Faster Better?

Purpose: The benefits of sutureless compared to conventional aortic valve prosthesis replacement remain controversial. Supposed advantages of sutureless aortic valve replacement include shortened cross-clamp and implantation time, as well as improved overall safety and good post-operative performance. We aimed to compare the early outcomes and performance of sutureless aortic valve replacement (su-AVR) with the sutureless Perceval (Corcym, Milan, Italy) vs. the conventional AVR with a conventional counterpart, in this case, the Labcor Dokimos Plus (LDP) aortic bioprosthesis. Methods: We compared two types of aortic valve prostheses, the sutureless (Corcym, Milan, Italy) and the conventional valve Labcor Dokimos Plus (LDP), implanted between August 2014 and May 2019 in our Department of Cardiac Surgery at RWTH Aachen University Hospital. Data were collected from 141 patients who received the Perceval (Corcym, Milan, Italy) and 138 who received the Labcor Dokimos Plus (LDP) aortic bioprosthesis. After matching the two groups considering STS mortality risk and pre-operative LDH levels, 201 patients were included in our final study cohort. Seventy-one patients (17 from the Perceval group and 54 from the Dokimos group) were excluded due to the lack of complete data, particularly standardized echocardiographic data (n = 71). Primary endpoints were 30-day mortality, length of hospital stay, and pacemaker implantation. Secondary endpoints were echocardiographic parameters, major adverse cardiovascular events, and prosthesis failure (grade II aortic regurgitation, paravalvular leak with reintervention). Results: Bypass and cross-clamp time proved to be shorter in the Perceval group, while hospital stays were longer. The faster implantation had no effect on the 30-day mortality primary endpoint. Transvalvular gradients were significantly higher in the Perceval group, in addition to a smaller effective orifice area. The LDH values were remarkably higher post-operatively in the Perceval group. Conclusions: Regarding the clinical outcomes, Perceval was equivalent and not superior to the Dokimus bioprosthesis. The suitability of a Perceval prosthesis implantation must be determined on a case-by-case basis and reserved for elderly patients with increased comorbidity.

How Controlled is the Expansion of VIATORR CX?

PURPOSE: To investigate and compare the physical properties of the new generation Gore VIATORR-Controlled Expansion Endoprosthesis (VCX) to those of the predecessor VIATORR stent in an in vitro experimental setup. MATERIALS AND METHODS: A total of 12 stents (8 VCX; 4 VIATORR; GORE, USA) were examined. Radial resistive force (RRF) and chronic outward force (COF) were assessed using a radial force testing machine (RX-650, Machine Solutions Inc., USA). To assess the radial forces of the VCX above 8 mm, balloon expansion was performed between cycles. RESULTS: All VCX stents show an abrupt decrease in COF at an external diameter of 8.3 mm; RRF decreases likewise at an external diameter of 8.5 mm. The predecessor VIATORR stent without the "controlled expansion" feature shows linear radial force reduction until full expansion at a diameter of 10 mm. The physical properties of the VCX can be altered by balloon modulation. Point of COF (RRF) reduction shifts to 8.5 mm (8.6 mm), 8.6 mm (8.8 mm) and 9.3 mm (9.6 mm) following modulation with a 8 mm, 9 mm and 10 mm balloon. CONCLUSIONS: The VCX shows an abrupt and disproportionate decrease in COF and RRF at an external diameter of 8.3 mm, thus passive expansion to its nominal diameter of 10 mm is not to be expected. By means of balloon dilatation the physical properties of the stent can be altered, enabling customized TIPS creation. The previous VIATORR stent shows continuous COF and RRF until total expansion.

Stent deformation in a sutureless aortic valve bioprosthesis: a pilot observational analysis using imaging and three-dimensional modelling.

OBJECTIVES: The goal of this analysis of the Perceval aortic bioprosthesis was to investigate the ovalization/deformation of the Perceval prosthesis stent after implantation and its propensity for cusp dysfunction, fluttering, fibrosis and blockage. METHODS: Between August 2014 and May 2019, a total of 134 patients (52% female) underwent aortic valve replacement with the Perceval bioprosthesis. We reconstructed three-dimensional models of the Perceval stent using thorax computed tomography scans for 16 patients employing the software Mimics (Materialise NV, Leuven, Belgium) and analysed the ovality of the stents. Radial force (RF) measurements were performed to compare the stiffness of the Perceval bioprosthesis to that of other valves. RESULTS: The three-dimensional reconstructions showed that all Perceval stents exhibited some degree of deformation and ovalization. Ovality in the annulus and commissure section of the Perceval stents ranged from 6.8% to 45% with mean values of 13.6% and 21.9%, respectively. The RF of the Perceval prosthesis was noticeably lower than that of the Edwards Intuity and several transcatheter aortic valve implantation devices. The stent adopted the preoperative shape of the aorta in the 2 patients for whom pre- and postoperative computed tomography data existed. CONCLUSIONS: The Perceval bioprostheses were deformed to different degrees in all analysed cases. The comparably low RFs might be an explanation for the propensity towards this deformation, which can lead to fluttering, a reduction of the cusps' mobility. This condition could potentially result in fibrosis as well as increased transvalvular pressure gradients and might be the cause for the increase in lactate dehydrogenase and the decrease in platelet count.

Comparison of Aspiration Catheters with Modified Standard Catheters for Treatment of Large Pulmonary Embolism Using an In-vitro Patho-Physiological Model.

PURPOSE: The presented in-vitro study provides a comparison of various catheters for mechanical treatment of large-burden pulmonary embolism (PE) under standardized conditions, using a new test rig. Dedicated aspiration catheters (JETi®, Penumbra Indigo®, Aspirex®) were compared with standard catheters (Pigtail, Multi-Purpose, Balloon Catheter) applied for embolus fragmentation. MATERIALS AND METHODS: Emboli prepared from porcine blood were washed into the test rig which consists of anatomical models of the pulmonary artery (PA) and of the right heart in combination with a pulsatile drive system. For all catheters, the duration of the recanalization procedure and the weight percentage (wt%) of the remaining, removed and washed-down clot fractions were evaluated. For aspiration catheters, the aspirated volume was measured. RESULTS: All catheters achieved full or partial recanalization. The aspiration catheters showed a significantly (p < 0.05) lower procedure time (3:15 min ± 4:26 min) than the standard fragmentation catheters (7:19 min ± 4:40 min). The amount of thrombus removed by aspiration was significantly (p < 0.001) higher than that by fragmentation, averaging 86.1 wt% ± 15.6 wt% and 31.7 wt% ± 3.8 wt%, respectively. Nonetheless, most of the residue was fragmented into pieces of ≥ 1 mm and washed down. Only in 2 of 36 tests, a residual thrombus of 11.9 wt% ± 5.1 wt% remained in the central PA. CONCLUSION: Comparison under standardized in-vitro patho-physiological conditions showed that embolus fragmentation with standard catheters is clearly inferior to aspiration with dedicated catheters in the treatment of large-burden PE, but can still achieve considerable success. LEVEL OF EVIDENCE: No level of evidence, experimental study.

Melt Electrowriting of Complex 3D Anatomically Relevant Scaffolds.

The manufacture of fibrous scaffolds with tailored micrometric features and anatomically relevant three-dimensional (3D) geometries for soft tissue engineering applications remains a great challenge. Melt electrowriting (MEW) is an advanced additive manufacturing technique capable of depositing predefined micrometric fibers. However, it has been so far inherently limited to simple planar and tubular scaffold geometries because of the need to avoid polymer jet instabilities. In this work, we surmount the technical boundaries of MEW to enable the manufacture of complex fibrous scaffolds with simultaneous controlled micrometric and patient-specific anatomic features. As an example of complex geometry, aortic root scaffolds featuring the sinuses of Valsalva were realized. By modeling the electric field strength associated with the MEW process for these constructs, we found that the combination of a conductive core mandrel with a non-conductive 3D printed model reproducing the complex geometry minimized the variability of the electric field thus enabling the accurate deposition of fibers. We validated these findings experimentally and leveraged the micrometric resolution of MEW to fabricate unprecedented fibrous aortic root scaffolds with anatomically relevant shapes and biomimetic microstructures and mechanical properties. Furthermore, we demonstrated the fabrication of patient-specific aortic root constructs from the 3D reconstruction of computed tomography clinical data.

Ghost Cells for Mechanical Circulatory Support In Vitro Testing: A Novel Large Volume Production.

The aim of this work is to establish a large volume batch production system to produce sufficient volumes of ghost cells to facilitate hemolysis testing of mechanical circulatory support devices. A volume of more than 405 mL with a hematocrit of at least 28% is required to perform in vitro hemolysis testing of mechanical circulatory support devices according to international standards. The established ghost cell production method performed at the institute is limited to 3.1 mL of concentrated cells, that is, cells with 100% hematocrit, due to predominantly manual process steps. Through semi-automation of the existing method by using the large volume batch production system, productivity is increased 60-fold to 188 mL while almost doubling process efficiency to 23.5%. Time-consuming manual work such as pipetting is now supported by sensor-based process engineering. With the help of the large volume batch production system, the objective of producing large quantities of ghost cells is successfully achieved. Thus, this work lays the foundation for spatially resolved hemolysis evaluation of mechanical circulatory support devices in combination with the small-scale fluorescent hemolysis detection method.

Mechanical properties of currently available left atrial appendage occlusion devices: A bench-testing analysis.

Endoluminal left atrial appendage occlusion is an emerging therapy to treat patients suffering from atrial fibrillation with contraindications against oral anticoagulation. Different occlusion devices have been introduced into the clinical setting while comparative studies between the devices are sparse. This in vitro study compares several endoluminal left atrial appendage occlusion systems regarding 2 mechanical properties: radial (RF) and tug force (TF). Seven different occluder systems of various sizes (24 in total) underwent testing throughout their recommended sizing range. RF was measured in a commercial RF tester. TF was assessed according to a recently published bench test. RF increased with compression of the devices: The LAmbre 2228 device exerted the highest RF (8.6 N) at maximum compression of 16 mm. The lowest RF of 0.1 N was exhibited by the 27 mm Occlutech occluder at minimal compression. The highest TFs were exerted by the WaveCrest devices at maximum compression with 4.6 and 3.6 N for the 22 mm and the 27 mm device, respectively. The lowest TFs were measured for the first-generation Occlutech devices, particularly for the 24 mm device with 1.1 N at maximum compression and 0.4 N at minimum compression. A strong positive correlation was found between the number of hooks per millimeter circumference of an occluder and its tug force (r = 0.87, P < 0.01). The analysis revealed device stability to be more dependent on anchoring structures than on RF. The wide range of mechanical properties makes comparison of current LAA occluders difficult and emphasizes the need for standardized preclinical testing to prompt clinical compatibility.

Mechanical Performance of Two Left Atrial Appendage Occlusion Systems: In Vitro Comparison of Tug Force, Radial Force, Sealing and Deformation.

The aim of this study was to establish in vitro bench-tests of left atrial appendage occlusion (LAAo) devices regarding tug force, radial force and sealing capacity. Two LAAo devices, namely the WATCHMAN™ and the Occlutech®, of three different sizes underwent testing in novel dedicated in vitro setups. Radial force was assessed in a commercial radial force tester. At baseline, tug force of the WATCHMAN™ was significantly higher when compared to Occlutech® for all devices. Repeated resheathing resulted in a reduction of device-diameter in the WATCHMAN™ devices of max. 7.9%, whereas diameters of Occlutech® occluders remained unchanged. Tug force was not significantly impacted by resheathing in both devices. At baseline, sealing capacity in a bench-test using silicone LAA-models did not differ between the devices. Resheathing lead to an in vitro loss of sealing capacity of the WATCHMAN™ devices, increasing with resheathing and resulting in a max. peridevice leak of 91.1 ± 7.9%. Radial force was higher for the Occlutech® devices and decreased for WATCHMAN™ occluders after resheathing. The WATCHMAN™ occluder series showed progressive deformation, increased peridevice leakage and decreased radial force after resheathing, presumably as a result of diameter reduction. Tug force of the WATCHMAN™ was not impaired by resheathing and was significantly higher than that of the Occlutech® device.

Physical Properties of Venous Stents: An Experimental Comparison.

PURPOSE: Iliocaval obstruction is a substantial contributor to chronic venous insufficiency and is increasingly being treated endovascularly with angioplasty and stent placement. Utilization of an appropriate stent for treatment is pivotal; however, until today, mechanical properties of venous stents remain unknown. MATERIALS AND METHODS: We analyzed the radial resistive force, the chronic outward force, as well as the crush resistance of seven stent models [Zilver Vena (Cook, Bjaeverskov, Denmark), Sinus Venous, Sinus Obliquus and Sinus XL Flex (Optimed, Ettlingen, Germany), Vici (Veniti; St. Louis, USA), Wallstent (Boston Scientific, Marlborough, USA), and Venovo (Bard, Tempe, USA)] in vitro using a radial force testing machine (RX-650, Machine Solutions Inc., Flagstaff, AZ, USA) and a hardness testing machine (zwickiLine, Zwick Roell, Ulm, Germany). RESULTS: The Sinus Obliquus revealed the highest radial resistive force (19.41 N/cm) and the highest chronic outward force at 50 and 30% nominal diameter (7.93 N/cm at 50%, 16.97 N/cm at 30%) while the Venovo revealed the highest chronic outward force at 90 and 80% nominal diameter (4.83 N/cm at 90%, 5.37 N/cm at 80%). The radial resistive force and the chronic outward force of the Wallstent greatly depended on whether the stent ends were fixated. The Wallstent revealed the highest crush resistance at nominal diameters of 90% (0.46 N/cm) to 60% (1.16 N/cm). The Sinus Obliquus revealed the highest crush resistance at a nominal diameter of 50% (1.41 N/cm). CONCLUSION: Venous stents greatly differ regarding their mechanical properties. These results should be considered when choosing an appropriate stent for the treatment of venous obstruction.