Dissection in a pulmonary autograft

Pregnancy outcomes in women following the Ross procedure

INTRODUCTION

The Ross procedure, where a pulmonary autograft (neoaorta) replaces the aortic valve, has excellent long-term outcomes in patients with congenital aortic valve disease. However, there are reports of neoaortic dilatation and dissection. An increasing number of women are wishing to become pregnant following the Ross procedure, but little is known about the occurrence and risks of neoaortic dilatation and complications in pregnancy. We investigated neoaorta function and outcomes in pregnancy following the Ross procedure.

METHODS

This retrospective study investigated women post-Ross procedure at a tertiary ACHD unit between 1997 and 2021. Imaging evaluated neoaortic root dimensions and regurgitation pre-, and post- pregnancy, compared with matched non-pregnant controls. Primary endpoints were change in neoaortic dimensions, degree of regurgitation and adverse maternal outcomes.

RESULTS

Nineteen pregnancies in 12 women were included. The mean change in neoaortic root diameter post-pregnancy was 1.8 mm (SD 3.4) (p = 0.017). There was no significant change in neoaortic dimensions in matched controls during follow-up. There were no cases of dissection, arrhythmia, acute coronary syndrome, or maternal mortality. Three deliveries were pre-term, including one emergency Caesarean section due to maternal cardiac decompensation, requiring aortic root replacement post-partum but there were no neonatal deaths.

CONCLUSIONS

Pregnancy following the Ross procedure is associated with neoaortic dilatation, and pregnancy is generally well tolerated. Although adverse maternal outcomes are uncommon, there are still rare cases of cardiac complications in and around the time of pregnancy. These findings emphasise the need for accessible pre-pregnancy counselling, risk stratification and careful surveillance through pregnancy by specialist cardio-obstetric multi-disciplinary teams.

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.

Autograft Root Dilation After the Ross Procedure Is Not Benign

Autograft root dilation is common after the unsupported Ross procedure. In the absence of valvar incompetence, and with the perception that dissection is exceedingly rare, expectant management of autograft aneurysm is common practice. Autograft dissection may not be as rare as thought though, as at this point 7 case reports have accrued that describe autograft dissection requiring urgent operative intervention. All had a bicuspid native aortic valve. Bicuspid aortic valve has been shown to be associated with an intrinsic, histologically demonstrated pulmonary arteriopathy, possibly contributing to autograft root dilation and dissection. Autograft root dilation can no longer be regarded as benign, especially in patients with bicuspid aortic valve. Mounting evidence further validates the practice of externally supporting the Ross autograft. For patients who have had an unsupported Ross procedure, mounting evidence may support earlier intervention for autograft root dilation and aneurysm.

Fallot Tetralogy with Dissected Pulmonary Artery Aneurysm: A Rare Case Report

Pulmonary artery dissection is a rare and extremely dangerous disease with high mortality rates. It is one of the most serious complications of chronic pulmonary hypertension. It may be related to chronic pulmonary hypertension and pulmonary artery dilatation. Early diagnosis of pulmonary dissection is particularly important because of its high mortality. Once the symptoms worsen or severe deterioration of the disease occurs, imaging examination should be performed promptly for early diagnosis and timely treatment.

Surgical repair of aortic dissection 16 years post-Ross procedure

The Ross procedure is an excellent choice for younger patients in need of aortic valve replacement. While patients have benefited from superior survival rates associated with this procedure, complications related to aortic root dilatation and degeneration of the autograft may be encountered later in life. These challenges may be exacerbated in those with underlying connective tissue abnormalities, a phenomenon commonly observed in the bicuspid aortic valve population. In this report, we present the case of a patient who presented with an aortic dissection 16 years after a Ross procedure for aortic insufficiency in the setting of a bicuspid aortic valve, and review the existing literature related to this adverse event.

The Ross procedure: state of the art 2011

The purpose of this paper is to review the current literature and practice of the Ross concept of using the autologous pulmonary valve to replace a diseased aortic valve. The potential advantages and disadvantages of these operations will be evaluated in the context of alternative options and relative risks. The different surgical techniques of subcoronary and full root methods will be discussed and important technical aspects reviewed. Long-term outcomes will be described to the extent these are available, including recent publications describing a survival advantage for the Ross. Brief discussions will be presented regarding hemodynamics, child-bearing, endocarditis, and the use of the Ross in pediatric patients as well as biological adaptability of the living pulmonary autograft.

Ross operation: 16-year experience

OBJECTIVE

We performed a review of a consecutive series of 487 patients undergoing the Ross operation to identify surgical techniques and clinical parameters that affect outcome.

METHODS

We performed a prospective review of consecutive patients from August 1986 through June 2002 and follow-up through August 2004. Patient age was 2 days to 62 years (median, 24 years), and 197 patients were less than 18 years of age. The Ross operation was performed as a scalloped subcoronary implant in 26 patients, an inclusion cylinder in 54 patients, root replacement in 392 patients, and root-Konno procedure in 15 patients. Clinical follow-up in 96% and echocardiographic evaluation in 77% were performed within 2 years of closure.

RESULTS

Actuarial survival was 82% +/- 6% at 16 years, and hospital mortality was 3.9%. Freedom from autograft failure (autograft reoperation and valve-related death) was 74% +/- 5%. Male sex and primary diagnosis of aortic insufficiency (no prior aortic stenosis) were significantly associated with autograft failure by means of multivariate analysis. Freedom from autograft valve replacement was 80% +/- 5%. Freedom from endocarditis was 95% +/- 2%. One late thromboembolic episode occurred. Freedom from allograft reoperation or reintervention was 82% +/- 4%. Freedom from all valve-related events was 63% +/- 6%. In children survival was 84% +/- 8%, and freedom from autograft valve failure was 83% +/- 6%.

CONCLUSIONS

The Ross operation provides excellent survival in adults and children willing to accept a risk of reoperation. Male sex and a primary diagnosis of aortic insufficiency had a negative effect on late results.

Degeneration of the pulmonary autograft: An explant study

OBJECTIVE

We sought to determine the histologic features of pulmonary autografts explanted after the Ross operation.

METHODS

Histologic sections of 30 explanted autografts and 8 normal heart valves were compared and semiquantitatively scored by a blinded cardiovascular pathologist.

RESULTS

Pulmonary autografts (n = 30) were explanted on average 6.1 +/- 0.6 years (median, 6.6 years; range, 0.1-11.7 years) after the Ross operation (n = 28) or removed at autopsy (n = 2). Twelve (43%) of the patients undergoing reoperation had no or negligible autograft insufficiency on early transthoracic echocardiography, 12 (43%) had grade 1 autograft insufficiency, and 4 (14%) had grade 1-2 autograft insufficiency. Valve regurgitation with root dilatation was the most common indication for reoperation after root replacement (n = 26 [93%]) and regurgitation after subcoronary implanted autografts (n = 2 [7%]). Microscopy of the autograft explants revealed normal laminar architecture and cellularity. Wall specimens were characterized by reduced and fragmented elastin and increased collagen levels (fibrosis). Medial elastin changes were associated with the presence of hypertrophic smooth muscle cells. Fibrosis was most severe in the adventitia. Intimal thickening was a common finding. Valve explants showed significant thickening caused by fibrocellular tissue on the ventricular surface and marked thickening of the free margin. An autopsy explant with normal function before death showed similar features.

CONCLUSIONS

Pulmonary autograft explants showed severe aneurysmal degeneration of the wall, which was characterized by intimal thickening, medial elastin fragmentation, and adventitial fibrosis. Valve leaflets were thickened. The presence of these features in a nonfailing explant suggests these changes represent a common mode of remodeling.

Aortic root disease after the Ross procedure

PURPOSE OF REVIEW

Autograft root pathology is the most common adverse event late after the Ross operation. Therefore, characterization of prevalence, risk factors and natural history of root disease, as well as identification of preventive and therapeutic strategies, is warranted.

RECENT FINDINGS

Autograft root pathology affects up to one third of long-term survivors of the Ross operation. Root replacement technique and preoperative aortic aneurysm are recurrent risk factors. Any age group, except for infants, may be affected. Dilatation is often progressive leading to valve regurgitation, true aneurysm, and, rarely, dissection. Primary prevention involves avoidance of root technique, graft repalcement of aneurysmal aorta, or modifications of the root technique. Use of beta-receptor antagonist or angiotensin converting enzyme-inhibitors for secondary prevention is still empirical. Indications to resection of root aneurysm are based on maximum root area indexed to body height. Reintervention prior to appearance of relevant valve insufficiency increases likelihood of pulmonary valve preservation. Definition of functional outcome after autograft valve-sparing procedures needs longer follow-up.

SUMMARY

Over a decade after worldwide embracement of the root replacement technique for the Ross procedure, autograft root pathology is emerging as a prevalent complication. Prophylactic and therapuetic strategies are proposed to mitigate the current and future impact of this phenomenon.