Supporting the Ross procedure: preserving root physiology while mitigating autograft dilatation

Our 7-year experience supporting the Ross autograft with the novel technique of Personalized External Aortic Root Support

Objective

The Ross operation is a widely accepted option for aortic valve replacement in children, and evidence shows its excellent results in terms of hemodynamics and durability. However, indications are still limited due to the fact that it is a technically demanding procedure, only performed by specialized surgeons. On top of that, and despite numerous techniques being applied, autograft dilatation remains a key disadvantage, which can lead to graft failure. In recent years, the ExoVasc Personalized External Aortic Root Support (PEARS) has proven to be a safe and effective option to prevent aortic root dilatation in various aortopathies and is a technique that lends itself to support the pulmonary autograft in the Ross operation.

Methods

During the past 7 years, we have used the ExoVasc PEARS graft, manufactured from the patients' pulmonary artery measurements from computed tomography scan data, to support the pulmonary autograft in the Ross operation. This graft (manufactured by Exstent Ltd, UK) is implanted at the same time as the autograft. We have reviewed all the patients who underwent this surgery, including demographic data, aorta measurements, operative data, and follow-up assessment consisting of periodic echocardiograms and magnetic resonance imaging scans.

Results

Fifty patients were included in the study. Mean age at the time of the operation was 29.84 years, the youngest patient was 9 years-old. Nineteen patients (38%) had previous sternotomies; 11 of them having had a previous aortic valve replacement. Seventy-two percent of patients had initially a bicuspid aortic valve. Mean diameter of the ascending aorta was 3.83 cm. Forty-four percent of patients required a concomitant reduction aortoplasty due to mismatch sizes between the ascending aorta and the autograft. Mean bypass and crossclamp times were 200.66 and 151.14 minutes, respectively. Median length of stay was 6 days. Mean follow-up was 16.88 months. Two patients required subsequent aortic valve replacement (1 had rheumatic valve disease and the other had iatrogenic damage in his autograft valve leaflet). Ascending aorta dimensions remain stable when compared with immediate postoperative studies. There were no deaths.

Conclusions

The ExoVasc PEARS graft has proven to be an excellent support in the Ross operation to prevent the autograft failure related to autograft dilatation that can offer several advantages compared with other existing techniques. With this type of support, we believe the Ross indications can be expanded to multiple clinical scenarios, given the good long-term results this operation offers in terms of durability, life expectancy, and hemodynamics.

Aortic Valve Embryology, Mechanobiology, and Second Messenger Pathways: Implications for Clinical Practice

During the Renaissance, Leonardo Da Vinci was the first person to successfully detail the anatomy of the aortic root and its adjacent structures. Ever since, novel insights into morphology, function, and their interplay have accumulated, resulting in advanced knowledge on the complex functional characteristics of the aortic valve (AV) and root. This has shifted our vision from the AV as being a static structure towards that of a dynamic interconnected apparatus within the aortic root as a functional unit, exhibiting a complex interplay with adjacent structures via both humoral and mechanical stimuli. This paradigm shift has stimulated surgical treatment strategies of valvular disease that seek to recapitulate healthy AV function, whereby AV disease can no longer be seen as an isolated morphological pathology which needs to be replaced. As prostheses still cannot reproduce the complexity of human nature, treatment of diseased AVs, whether stenotic or insufficient, has tremendously evolved, with a similar shift towards treatments options that are more hemodynamically centered, such as the Ross procedure and valve-conserving surgery. Native AV and root components allow for an efficient Venturi effect over the valve to allow for optimal opening during the cardiac cycle, while also alleviating the left ventricle. Next to that, several receptors are present on native AV leaflets, enabling messenger pathways based on their interaction with blood and other shear-stress-related stimuli. Many of these physiological and hemodynamical processes are under-acknowledged but may hold important clues for innovative treatment strategies, or as potential novel targets for therapeutic agents that halt or reverse the process of valve degeneration. A structured overview of these pathways and their implications for cardiothoracic surgeons and cardiologists is lacking. As such, we provide an overview on embryology, hemodynamics, and messenger pathways of the healthy and diseased AV and its implications for clinical practice, by relating this knowledge to current treatment alternatives and clinical decision making.

Late Pulmonary Autograft Dilation: Can We Make a Good Operation Great? The Tailored Approach

While it is the main viable option in the growing child and young adult, the Ross procedure has expanded its applicability to older patients, for whom long-term results are equivalent, if not superior, to prosthetic aortic valve replacement. Strategies aiming at mitigating long-term autograft failure from root enlargement and valve regurgitation have led some to advocate for root reinforcement with prosthetic graft material. On the contrary, we will discuss herein the rationale for a tailored approach to the Ross procedure; this strategy is aimed at maintaining the natural physiology and interplay between the various autograft components. Several technical maneuvers, including careful matching of aortic and autograft annuli and sino-tubular junction as well as external support by autologous aortic tissue maintain these physiologic relationships and the viability of the autograft, and could translate in a lower need for late reintervention because of dilation and/or valve regurgitation.

Personalized external aortic root support in aneurysm disease

PURPOSE OF REVIEW

To bring together and annotate publications about personalised external aortic root support reported in the 18 months preceding submission.

RECENT FINDINGS

The total number of personalised external aortic root support (PEARS) operations is now approaching 700 in 30 centres in Australia, Belgium, Brazil, Czech Republic, Great Britain, Greece, Ireland, Malaysia, Netherlands, New Zealand, Poland and Slovakia. There are continued reports of stability of aortic dimensions and aortic valve function with the only exceptions known being where the surgeon has deviated from the instructions for use of the device. The median root diameter of Marfan patients having PEARS was 47 mm suggesting that the existing criterion of 50 mm is due for reconsideration. The peri-operative mortality currently estimated to be less than 0.3%. The first recipient remains alive and well after 18 years. The use of PEARS as an adjunct to the Ross operation to support the pulmonary autograft is being explored in several centres.

SUMMARY

The operation requires proctoring and adherence to a strict operative protocol and with those precautions excellent results are attained. The evidence and opinions provided in the cited publications indicate that PEARS is a proven and successful prophylactic operation for aortic root aneurysm.