Comparison of Dacron ring and suture annuloplasty for aortic valve repair-a porcine study

A 3D-Printed Externally Adjustable Symmetrically Extensible (EASE) Aortic Annuloplasty Ring for Root Repair and Aortic Valve Regurgitation

PURPOSE

The valve-sparing aortic root replacement (VSARR) procedure was developed to preserve the aortic valve apparatus to replace aneurysmal aortic roots with synthetic grafts and to eliminate associated aortic regurgitation (AR). However, residual post-repair AR is not uncommon and has been found to be associated with recurrent AR and future reoperation.

METHODS

We designed and manufactured a 3D-printed, external adjustable symmetrically extensible (EASE) aortic annuloplasty ring that can symmetrically reduce the aortic annulus diameter via a radial constriction, compliant mechanism. An ex vivo porcine VSARR model with annular dilation and AR was developed (n = 4) and used for hemodynamic, echocardiography, and high-speed videography data collection.

RESULTS

After ring annuloplasty repair using the EASE aortic ring, the regurgitant fraction decreased from 23.6 ± 6.9% from the VSARR model to 7.4 ± 5.6% (p = 0.05), which was similar to that measured from baseline with a regurgitant fraction of 10.2 ± 3.9% (p = 0.34). The leaflet coaptation height after annuloplasty repair also significantly increased from that measured in VSARR model (0.4 ± 0.1 cm) to 0.9 ± 0.1 cm (p = 0.0004), a level similar to that measured in baseline (1.1 ± 0.1 cm, p = 0.28).

CONCLUSION

Using an ex vivo VSARR model, the EASE ring successfully reduced AR by reducing the annular diameter and improving leaflet coaptation. With its broad applicability and ease of use, this device has the potential to have a significant impact on patients suffering worldwide from AR due to root aneurysms.

Novel Expansible Aortic Annuloplasty Ring Exhibits Similar Characteristics as the Dacron Ring-an In Vitro Evaluation

An increasing body of research indicates that annular stability plays a key role for a successful aortic valve repair. The aim of this study was to evaluate and compare a novel open aortic annuloplasty ring (the A-ring) with the Dacron ring. Both rings were compared with native aortic roots in vitro. Eighteen aortic roots were included in the study and randomized into three groups: the native, Dacron, and A-ring group. The roots were evaluated in an in vitro physiologic pulsatile model simulating the left side of the heart. Aortic annulus diameters were significantly reduced both in the Dacron ring group (p = 0.003) and the A-ring group (p = 0.020) when compared with the native group. Both the Dacron ring and A-ring effectively downsized the aortic annulus diameter. The A-ring also displayed an ability to maintain aortic root distensibility during the cardiac cycle equally to the Dacron ring.

Ex vivo biomechanical analysis of the Ross procedure using the modified inclusion technique in a 3-dimensionally printed left heart simulator

OBJECTIVE

The inclusion technique was developed to reinforce the pulmonary autograft to prevent dilation after the Ross procedure. Anticommissural plication (ACP), a modification technique, can reduce graft size and create neosinuses. The objective was to evaluate pulmonary valve biomechanics using the inclusion technique in the Ross procedure with and without ACP.

METHODS

Seven porcine and 5 human pulmonary autografts were harvested from hearts obtained from a meat abattoir and from heart transplant recipients and donors, respectively. Five additional porcine autografts without reinforcement were used as controls. The Ross procedure was performed using the inclusion technique with a straight polyethylene terephthalate graft. The same specimens were tested both with and without ACP. Hemodynamic parameter data, echocardiography, and high-speed videography were collected via the ex vivo heart simulator.

RESULTS

Porcine autograft regurgitation was significantly lower after the use of inclusion technique compared with controls (P < .01). ACP compared with non-ACP in both porcine and human pulmonary autografts was associated with lower leaflet rapid opening velocity (3.9 ± 2.4 cm/sec vs 5.9 ± 2.4 cm/sec; P = .03; 3.5 ± 0.9 cm/sec vs 4.4 ± 1.0 cm/sec; P = .01), rapid closing velocity (1.9 ± 1.6 cm/sec vs 3.1 ± 2.0 cm/sec; P = .01; 1.8 ± 0.7 cm/sec vs 2.2 ± 0.3 cm/sec; P = .13), relative rapid opening force (4.6 ± 3.0 vs 7.7 ± 5.2; P = .03; 3.0 ± 0.6 vs 4.0 ± 2.1; P = .30), and relative rapid closing force (2.5 ± 3.4 vs 5.9 ± 2.3; P = .17; 1.4 ± 1.3 vs 2.3 ± 0.6; P = .25).

CONCLUSIONS

The Ross procedure using the inclusion technique demonstrated excellent hemodynamic parameter results. The ACP technique was associated with more favorable leaflet biomechanics. In vivo validation should be performed to allow direct translation to clinical practice.

Biomechanical evaluation of aortic regurgitation from cusp prolapse using an ex vivo 3D-printed commissure geometric alignment device

BACKGROUND

Aortic regurgitation (AR) is one of the most common cardiac valvular diseases, and it is frequently caused by cusp prolapse. However, the precise relationship of commissure position and aortic cusp prolapse with AR is not fully understood. In this study, we developed a 3D-printed commissure geometric alignment device to investigate the effect of commissure height and inter-commissure angle on AR and aortic cusp prolapse.

METHODS

Three porcine aortic valves were explanted from hearts obtained from a meat abattoir and were mounted in the commissure geometric alignment device. Nine commissure configurations were tested for each specimen, exploring independent and concurrent effects of commissure height and inter-commissure angle change on AR and aortic cusp prolapse. Each commissure configuration was tested in our 3D printed ex vivo left heart simulator. Hemodynamics data, echocardiography, and high-speed videography were obtained.

RESULTS

AR due to aortic cusp prolapse was successfully generated using our commissure geometric alignment device. Mean aortic regurgitation fraction measured for the baseline, high commissure, low commissure, high commissure and wide inter-commissure angle, high commissure and narrow inter-commissure angle, low commissure and wide inter-commissure angle, low commissure and narrow inter-commissure angle, wide commissure, and narrow commissure configurations from all samples were 4.6 ± 1.4%, 9.7 ± 3.7%, 4.2 ± 0.5%, 11.7 ± 5.8%, 13.0 ± 8.5%, 4.8 ± 0.9%, 7.3 ± 1.7%, 5.1 ± 1.2%, and 7.1 ± 3.1%, respectively.

CONCLUSIONS

AR was most prominent when commissure heights were changed from their native levels with concomitant reduced inter-commissure angle. Findings from this study provide important evidence demonstrating the relationship between commissure position and aortic cusp prolapse and may have a significant impact on patient outcomes after surgical repair of aortic valves.

Valve-sparing aortic root replacement: a primer for cardiologists

PURPOSE OF REVIEW

The purpose of this article is to review the contemporary evidence supporting valve-sparing aortic root replacement as the best option for patients with aortic root aneurysms and preservable aortic valves as well as to review the technical variations and modern adjuncts of these operations that impact both short and long-term durability.

RECENT FINDINGS

In patients with an aortic root aneurysm, with or without aortic valve regurgitation, valve-sparing aortic root replacement provide excellent clinical outcomes and stable valve function over several decades. Successful execution of this operation depends on careful patient selection and a thorough understanding of the anatomical and physiological relationships between the various components of the aortic root. Echocardiography remains the mainstay of imaging to determine the feasibility of valve-sparing root replacement.

SUMMARY

Valve-sparing aortic root replacement is an excellent alternative to composite valve graft replacement in nonelderly patients with aortic root aneurysms. Dedicated aortic root surgeons perform several technical variations of valve-sparing procedures aimed at matching the specific aortic root disorder with the optimal operation.

Novel bicuspid aortic valve model with aortic regurgitation for hemodynamic status analysis using an ex vivo simulator

OBJECTIVE

The objective was to design and evaluate a clinically relevant, novel ex vivo bicuspid aortic valve model that mimics the most common human phenotype with associated aortic regurgitation.

METHODS

Three bovine aortic valves were mounted asymmetrically in a previously validated 3-dimensional-printed left heart simulator. The non-right commissure and the non-left commissure were both shifted slightly toward the left-right commissure, and the left and right coronary cusps were sewn together. The left-right commissure was then detached and reimplanted 10 mm lower than its native height. Free margin shortening was used for valve repair. Hemodynamic status, high-speed videography, and echocardiography data were collected before and after the repair.

RESULTS

The bicuspid aortic valve model was successfully produced and repaired. High-speed videography confirmed prolapse of the fused cusp of the baseline bicuspid aortic valve models in diastole. Hemodynamic and pressure data confirmed accurate simulation of diseased conditions with aortic regurgitation and the subsequent repair. Regurgitant fraction postrepair was significantly reduced compared with that at baseline (14.5 ± 4.4% vs 28.6% ± 3.4%; P = .037). There was no change in peak velocity, peak gradient, or mean gradient across the valve pre- versus postrepair: 293.3 ± 18.3 cm/sec versus 325.3 ± 58.2 cm/sec (P = .29), 34.3 ± 4.2 mm Hg versus 43.3 ± 15.4 mm Hg (P = .30), and 11 ± 1 mm Hg versus 9.3 ± 2.5 mm Hg (P = .34), respectively.

CONCLUSIONS

An ex vivo bicuspid aortic valve model was designed that recapitulated the most common human phenotype with aortic regurgitation. These valves were successfully repaired, validating its potential for evaluating valve hemodynamics and optimizing surgical repair for bicuspid aortic valves.

The importance of collagen composition and biomechanics for the porcine aortic root

A thorough understanding of the aortic root structure and biomechanics is necessary when performing aortic valve-sparing procedures in patients with aortic root aneurysms. This study aimed to evaluate the amount of collagen and biomechanics at different levels and segments of the aortic root. Ten aortic roots from healthy pigs were excised including the aortic annulus, the sinuses of Valsalva, and the sinotubular junction (STJ). Specimens were further divided into three circumferential segments; left coronary (LC)-, right coronary (RC)-, and non-coronary (NC) sinus. Collagen was determined using hydroxyproline analysis and specimens were tested biomechanically for stress-strain relations. The annulus showed significantly larger average maximum stiffness (9.6 ± 4.5 N/mm) compared with the sinus (4.5 ± 2.0 N/mm) and STJ (4.8 ± 1.8 N/mm). The average collagen content was likewise higher in the annulus (4.0 ± 1.0 mg/ml) compared with the sinus (2.4 ± 0.6 mg/ml) and STJ (2.2 ± 0.5 mg/ml) for all three segments. The NC sinus segment exhibited a significantly larger maximum stiffness and stress under static conditions compared with the RC. These results suggest that the aortic root is heterogeneous in both structure and biomechanical properties and that it varies both in levels and segments of the aortic root. Future surgical approaches should consider enhanced strength parameters for specific areas of the aortic root to achieve the best results when performing aortic valve-sparing techniques. From this study, we conclude that the aortic annulus needs special attention to imitate normal physiologic properties during aortic valve-sparing surgery due to its higher maximum stiffness, stress, and load. Modified future surgical procedures could potentially prevent recurrent aneurysmal formation.

Valve sparing root replacement: an update

PURPOSE OF REVIEW

Until the year 2000, the publications concerning aortic valve sparing (AVS) did not exceed 20 articles; in the following years almost 300 publications have appeared. Over 35 years from the introduction of valve sparing techniques and 500 years after the death of Leonardo da Vinci, this review highlights the significant steps in modern imaging techniques and the excellent clinical results in the field of reconstructive aortic root surgery.

RECENT FINDINGS

AVS operations underwent significant modifications over the last few years making it reproducible with satisfactory outcomes. The extraordinary potential of imaging opens new boundless horizons in the perspective of an increasingly patient-tailored surgical planning. The basic surgical concepts include the preservation and resuspension of the aortic valve in a near-normal environment (with the creation of functionally suited neo-aortic sinuses) and the re-establishment of a normal relationship of the aortic root components.

SUMMARY

Today is possible to perform a reimplantation procedure with the creation of neo-sinuses or a remodeling procedure with the addition of annular support. Both procedures can now guarantee an anatomical root reconstruction and an increased long-term durability. AVS operations have become established alternatives to Bentall procedures for patients with aortic root pathology, especially in young patients.

A Novel Aortic Regurgitation Model from Cusp Prolapse with Hemodynamic Validation Using an Ex Vivo Left Heart Simulator

Although ex vivo simulation is a valuable tool for surgical optimization, a disease model that mimics human aortic regurgitation (AR) from cusp prolapse is needed to accurately examine valve biomechanics. To simulate AR, four porcine aortic valves were explanted, and the commissure between the two largest leaflets was detached and re-implanted 5 mm lower to induce cusp prolapse. Four additional valves were tested in their native state as controls. All valves were tested in a heart simulator while hemodynamics, high-speed videography, and echocardiography data were collected. Our AR model successfully reproduced cusp prolapse with significant increase in regurgitant volume compared with that of the controls (23.2 ± 8.9 versus 2.8 ± 1.6 ml, p = 0.017). Hemodynamics data confirmed the simulation of physiologic disease conditions. Echocardiography and color flow mapping demonstrated the presence of mild to moderate eccentric regurgitation in our AR model. This novel AR model has enormous potential in the evaluation of valve biomechanics and surgical repair techniques. Graphical Abstract.