The Ross Procedure in Adults: Long-Term Follow-Up and Echocardiographic Changes Leading to Pulmonary Autograft Reoperation

Understanding Pulmonary Autograft Remodeling After the Ross Procedure: Stick to the Facts

The Ross, or pulmonary autograft, procedure presents a fascinating mechanobiological scenario. Due to the common embryological origin of the aortic and pulmonary root, the conotruncus, several authors have hypothesized that a pulmonary autograft has the innate potential to remodel into an aortic phenotype once exposed to systemic conditions. Most of our understanding of pulmonary autograft mechanobiology stems from the remodeling observed in the arterial wall, rather than the valve, simply because there have been many opportunities to study the walls of dilated autografts explanted at reoperation. While previous histological studies provided important clues on autograft adaptation, a comprehensive understanding of its determinants and underlying mechanisms is needed so that the Ross procedure can become a widely accepted aortic valve substitute in select patients. It is clear that protecting the autograft during the early adaptation phase is crucial to avoid initiating a sequence of pathological remodeling. External support in the freestanding Ross procedure should aim to prevent dilatation while simultaneously promoting remodeling, rather than preventing dilatation at the cost of vascular atrophy. To define the optimal mechanical properties and geometry for external support, the ideal conditions for autograft remodeling and the timeline of mechanical adaptation must be determined. We aimed to rigorously review pulmonary autograft remodeling after the Ross procedure. Starting from the developmental, microstructural and biomechanical differences between the pulmonary artery and aorta, we review autograft mechanobiology in relation to distinct clinical failure mechanisms while aiming to identify unmet clinical needs, gaps in current knowledge and areas for further research. By correlating clinical and experimental observations of autograft remodeling with established principles in cardiovascular mechanobiology, we aim to present an up-to-date overview of all factors involved in extracellular matrix remodeling, their interactions and potential underlying molecular mechanisms.

Systematic review and meta-analysis of long-term outcomes in adults undergoing the Ross procedure

Background

The management of aortic valve disease is becoming increasingly complicated with the evolution of treatment options available to cardiac surgeons and cardiologist. Pulmonary autograft replacement of the aortic valve, commonly known as the Ross procedure, involves excision of the pulmonary valve from the right ventricular outflow tract and implantation in the aortic position. This systematic review aims to evaluate the long-term outcomes, following the Ross procedure.

Methods

An electronic search strategy queried five online medical referencing databases from inception to 21 August 2020. All studies detailing the long-term outcomes of adults undergoing the Ross procedure were included. A random effects model was used to determine pooled continuous data. Enhanced secondary survival analysis was performed on reconstructed individual patient data.

Results

Twenty-three studies were included in the qualitative synthesis, including a total of 6,278 patients with a mean follow-up duration of 6.0±2.8 years. Long-term survival was 95.6%, 91.8%, 86.3% and 80.5% at five, ten, fifteen and twenty years, respectively. Freedom from autograft reoperation was 95.7%, 91.2%, 84.9% and 76.1% at five, ten, fifteen and twenty years, respectively.

Conclusions

When performed in experienced centres and for appropriately selected patients, the Ross procedure represents a durable replacement of the aortic valve with excellent long-term survival.

The long term results of the Ross procedure: The importance of candidate selection

The Ross procedure has been considered in children as an optimal surgical procedure due to potential growth of the aortic annulus, lack of anticoagulation requirement, very low morbidity rate and excellent survival. Five-hundred-thirty-six (366 male, mean age 29.4 ± 11.1 years) underwent Ross procedure between 1990 and 2016 and had complete clinical and echocardiographic follow-up. Mean follow-up was 16.3 ± 4.9 years. Patients were divided in 2 groups according to age at surgery. Group 1 consisted of 320 (60%) patients less than 18 years old (223 male, mean age at surgery of 9.5 ± 5.6 years). Group 2 consisted of 216 (40%) patients older than 18 years of age (143 male, mean age at surgery of 26.3 ± 8.2 years). One-hundred-thirty (24%) patients had a redo procedure or surgery. Freedom from all re-operation and or percutaneous reintervention on either the aortic and pulmonary valves was 99% after 1 year, 94% after 5 years, 89% after 10 years, 83% after 15 years and 78% after 20 years. Freedom from redo surgery for AV 99% after 1 year, 94% after 5 years, 90% after 10 years, 81% after 15 years and 80% after 20 years. Freedom from redo surgery for PV was 100% after 1 year, 95% after 5 years, 89% after 10 years, 78% after 15 years and 76% after 20 years. The ideal candidate for Ross operation is a patient with congenital aetiology and an aortic root diameter ≤ 15 mm/m². A pulmonary fresh preserved homograft seems to perform better on the long term.

Outcomes and Quality of Life After Ross Reintervention: Would You Make the Same Choice Again?

BACKGROUND

The Ross procedure was introduced as a long-term if not definitive solution for aortic pathology. However, the rate of reoperation is not negligible.

METHODS

This single-center prospective study assessed the general outcome of Ross reoperation and patients' perceived quality of life compared with 2 control groups (Ross non-reoperation and mechanical aortic valve replacement). Patient's preference regarding the choice between mechanical aortic valve and Ross procedure was investigated in a subgroup that could theoretically have been directed to either of the 2 procedures.

RESULTS

Between 2005 and 2017, 64 consecutive patients underwent reoperation after Ross. Median age was 31 years. Median freedom from reoperation after the Ross procedure was 136 months. An autograft reoperation was required in 49, and 25 had homograft failure. No in-hospital death was recorded. Mean follow-up was 77 months (range, 6-164 months). Quality of life was assessed with the 36-Item Short Form Health Survey questionnaire. The Ross reoperation group showed a lower score involving psychological concerns compared with the other groups. In the reoperated-on patients group, 52 had adequate aortic annulus dimensions to receive a prosthetic valve instead of a Ross procedure. When asked whether they would make the same choice, only 31% confirmed the preference.

CONCLUSIONS

Reoperations after Ross procedure have low mortality and morbidity. Long-term follow-up showed a high quality of life, even after reoperations. However, owing to psychological concerns after the redo operation, when choosing a Ross procedure, it is our duty to thoroughly explain to patients that a high level of disillusion is predictable in case of reoperations.

A review of pulmonary autograft external support in the Ross procedure

Introduction: Although the Ross procedure offers several advantages over standard prosthetic AVR, its use remains limited. The risk of pulmonary autograft dilatation requiring reintervention remains one of the main concerns. Consequently, multiple techniques have been developed in attempt to mitigate this complication.Areas covered: This article reviews the incidence of pulmonary autograft dilatation, its risk factors and pathophysiology. The techniques of external pulmonary autograft support are discussed along with their respective advantages and limitations. Finally, future areas of research and developments are examined.Expert opinion: The risk of autograft dilatation is mainly prevalent in patients with aortic regurgitation and a dilated aortic annulus. In these selected patients, an external support may prevent dilatation of the autograft. However, any permanent support potentially restricts autograft root motion, mitigating some of the advantages associated with the Ross procedure. A bioresorbable matrix that could support the root during its initial adaptative phase could alleviate this problem. In our opinion, aggressive blood pressure control during the first postoperative year along with annular and sino-tubular junction support in selected patients provides optimal stability of autograft root dimensions while preserving root dynamics. Serial imaging and clinical follow-up are necessary to define the role of these various strategies.

Surgical Relief of Left Ventricular Outflow Tract Obstruction in Adults With Congenital Aortic Stenosis and Associated Aortic Annulus Hypoplasia and/or Subaortic Obstruction

BACKGROUND

In children and adolescents, a Ross/Konno operation is commonly done to both enlarge the aortic root and provide a competent aortic valve with relief of left ventricular outflow tract obstruction (LVOTO). Optimum management is not so straightforward in adults.

METHODS

Between 1995 and 2014, 16 patients of mean age 39.4 years (18-57 years) with hypoplastic aortic annulus (AA) measuring 20mm and less, and mean aortic valve/LVOT gradient of 61mmHg (30-70mmHg) presented for surgery.

RESULTS

Eight patients with mean LVOT/AA diameter 19.6mm (18-20mm) underwent an "inclusion-cylinder" type Ross procedure (RP). Eight patients with more severe LVOT/AA obstruction, with mean diameter of 17.4mm (16-19mm) underwent mechanical aortic valve replacement (AVR) with standard Konno-type aortoventriculoplasty. There was zero early and late mortality; with mean follow-up of 11.6 years (3-21 years) in the Ross group and 6 years (2-10 years) in the Konno-AVR group. One patient in the Konno-AVR group had reoperation after 2 years for RVOT obstruction. The postoperative echocardiograms of these patients at last follow-up show residual mean gradient across LVOT/AA of 4.4mmHg (2-6mmHg) after RP, and 11.9mmHg (8-17mmHg) after Konno-AVR.

CONCLUSIONS

In adults, the "inclusion-cylinder" Ross-procedure is a good alternative for mild to moderate aortic root hypoplasia. However, for cases with severe LVOT obstruction, a Ross-Konno is not possible with the same method of autologous support used in a non-Konno RP, and this could be expected to have an impact on late durability and the need for further intervention, in a group that has already undergone multiple procedures in childhood. Both methods of RP and Konno-AVR lead to excellent early and late results.

Pre- and Postoperative Imaging of the Aortic Root

Three-dimensional datasets acquired using computed tomography and magnetic resonance imaging are ideally suited for characterization of the aortic root. These modalities offer different advantages and limitations, which must be weighed according to the clinical context. This article provides an overview of current aortic root imaging, highlighting normal anatomy, pathologic conditions, imaging techniques, measurement thresholds, relevant surgical procedures, postoperative complications and potential imaging pitfalls. Patients with a range of clinical conditions are predisposed to aortic root disease, including Marfan syndrome, bicuspid aortic valve, vascular Ehlers-Danlos syndrome, and Loeys-Dietz syndrome. Various surgical techniques may be used to repair the aortic root, including placement of a composite valve graft, such as the Bentall and Cabrol procedures; placement of an aortic root graft with preservation of the native valve, such as the Yacoub and David techniques; and implantation of a biologic graft, such as a homograft, autograft, or xenograft. Potential imaging pitfalls in the postoperative period include mimickers of pathologic processes such as felt pledgets, graft folds, and nonabsorbable hemostatic agents. Postoperative complications that may be encountered include pseudoaneurysms, infection, and dehiscence. Radiologists should be familiar with normal aortic root anatomy, surgical procedures, and postoperative complications, to accurately interpret pre- and postoperative imaging performed for evaluation of the aortic root. Online supplemental material is available for this article.

The Ross procedure using autologous support of the pulmonary autograft: techniques and late results

OBJECTIVES

It is hypothesized that by performing radical aortic root manipulation and then autologous support for the pulmonary autograft in the Ross procedure, this will maintain aortic root size and should, in turn, lead to the demonstrated low incidence of late aortic regurgitation and need for reoperation on the aortic root and valve.

METHODS

Aortic root size was measured echocardiographically both preoperatively and then at second yearly intervals in 322 consecutive patients who underwent a Ross operation between October 1992 and June 2013 with autologous support of the pulmonary autograft root using the patient's own aorta. This technique, a variant of the inclusion cylinder method, has been developed with the aim of minimizing prosthetic materials in the aortic root.

RESULTS

Measures to reduce aortic root size included annulus reduction in 201 patients (62.4%) and reduction in aortic sinus or sinotubular junction in 159 patients (49.4%). Maximal aortic root diameter postoperatively at 5, 10, and 15 years was 34.0, 34.6, and 34.7 mm, respectively. Eleven reoperations were required during the study period for progressive aortic regurgitation (none for aortic root enlargement), with freedom from reoperation being 96% at both 15 years and 18 years. Preoperative pure aortic regurgitation, aortic annulus, and sinotubular junction enlargement were risk factors for reoperation.

CONCLUSIONS

This inclusion method of pulmonary autograft implantation leads to minimal increases in aortic root size over time, with no reoperations for aortic root dilatation and a low requirement for aortic valve reoperation. The Ross procedure deserves to remain on the surgical menu for aortic valve replacement.

Type I and Type II hybrid aortic arch replacement: postoperative and mid-term outcome analysis

BACKGROUND

Hybrid aortic arch replacement has emerged as a safe treatment modality for arch aneurysms, especially in patients of old age and with greater comorbid burden. We assessed our institutional outcomes in patients undergoing Types I and II hybrid aortic arch replacement.

METHODS

From 2005 to 2012, 685 patients underwent thoracic endovascular repair (TEVAR), of whom 104 had hybrid arch repair (open + endovascular approach). 47 of these patients had treatment for aortic arch aneurysm ± proximal ascending aortic aneurysm. The hybrid repair entailed aortic arch vessel debranching and concomitant/delayed antegrade ± retrograde TEVAR stent grafting of the arch. Type III patients were excluded from the analysis. Data was prospectively maintained.

RESULTS

28 patients had Type I repair, 8 had Type II repair, and 11 had Type III repair. Mean age was 71±8 years. Primary aortic pathology was aneurysm (81%), followed by chronic arch dissection (11%). 14% of patients required reoperative cardiac surgery. Stent graft deployment rate was 100% after arch vessel debranching. Postoperative endoleak rate was zero. Average cardiopulmonary bypass time was 215±64 minutes, with crossclamp time of 70±55 minutes, and circulatory arrest time of 50±17 minutes. Paraplegia rate was 5.5% (n=2), with stroke rate of 8% (n=3) and renal failure rate of 3% (n=1) requiring hemodialysis. In-hospital mortality was 8% (n=3). Mean length of stay was 17.2±14 days. Median follow-up was 30±21 months. Freedom from all-cause mortality was 71%, 60%, and 48% at 1, 3, and 5 years respectively. Aortic reoperation rate was 2.7% (n=1). No patient had Type I or III endoleak at follow-up. Freedom from mortality was improved in cases performed more recently (July 2008 to 2012) than during our early experience (2005 to June 2008) (81% versus 44% at 3 years, P=0.05).

CONCLUSIONS

Hybrid aortic arch replacement can be performed with good postoperative and midterm results in a cohort of old patients with significant comorbidity. With greater experience, early and midterm outcomes continue to improve. The hybrid arch technique may represent a technical advancement in the field of aortic arch surgery.

Inclusion cylinder method for aortic valve replacement utilising the Ross operation in adults with predominant aortic stenosis - 99% freedom from re-operation on the aortic valve at 15 years

BACKGROUND

To report our experience with the Ross operation in patients with predominant aortic stenosis (AS) using an inclusion cylinder (IC) method.

METHODS

Out of 324 adults undergoing a Ross operation, 204 patients of mean age of 41.3 years (limits 16-62) underwent this procedure for either AS or mixed AS and regurgitation (AS/AR) between October, 1992 and February, 2012, implanting the PA with an IC method. Clinical follow up and serial echo data for this group is 97% complete with late mortality follow up 99% complete.

RESULTS

There has been zero (0%) early mortality, and late survival at 15 years is 98% (96%, 100%). Only one re-operation on the aortic valve for progressive aortic regurgitation (AR) has been required with freedom from re-operation on the aortic valve at 15 years being 99% (96%, 100%). The freedom from all re-operations on the aortic and pulmonary valves at 15 years is 97% (94%, 100%). Echo analysis at the most recent study shows that 98% have nil, trivial or mild AR. Aortic root size has remained stable, shown by long-term (15 year) echo follow up.

CONCLUSIONS

In an experience spanning 19 years, the Ross operation used for predominant AS using the IC method described, results in 99% freedom from re-operation on the aortic valve at 15 years, better than any other tissue or mechanical valve. For adults under 65 years without significant co-morbidities who present with predominant AS, the pulmonary autograft inserted with this technique gives excellent results.

Current developments in the tissue engineering of autologous heart valves: moving towards clinical use

The use of tissue-engineering methods to create autologous heart valve constructs has the potential to overcome the fundamental drawbacks of more traditional valve prostheses. Traditional mechanical valves, while durable, increase the risk for endocarditis and thrombogenesis, and require the recipient to continue lifelong anticoagulant therapy. Homograft or xenograft heart valve prostheses are associated with immune reaction and progressive deterioration with limited durability. Most importantly, neither option is capable of growth and remodeling in vivo and both options place the patient at risk for valve-related complications and reoperation. These shortcomings have prompted the application of tissue-engineering techniques to create fully autologous heart valve replacements. Future clinically efficacious tissue-engineered autologous valves should be nonthrombogenic, biocompatible, capable of growth and remodeling in vivo, implantable with current surgical techniques, hemodynamically perfect, durable for the patient’s life and most importantly, significantly improve quality of life for the patient. In order to meet these expectations, the nature of the ideal biochemical milieu for conditioning an autologous heart valve will need to be elucidated. In addition, standardized criteria by which to quantitatively evaluate a tissue-engineered heart valve, as well as noninvasive analytical techniques for use in long-term animal models, will be required. This article highlights the advances, challenges and future clinical prospects in the field of tissue engineering of autologous heart valves, focusing on progress made by studies that have investigated a fully autologous, tissue-engineered pulmonary valve replacement in vivo.