Autograft remodeling after the Ross procedure by cardiovascular magnetic resonance imaging: Aortic stenosis versus insufficiency

Ross Procedure for Aortic Regurgitation versus Stenosis in Adults With and Without Autograft Support

OBJECTIVES

The Ross procedure for aortic regurgitation (AR) and abnormal aortic valve morphologies is associated with an increased risk of autograft dilatation. Autograft support may ameliorate this problem. We analysed the results for all haemodynamic lesions and the effect of autograft support.

METHODS

A retrospective analysis was conducted of patients who underwent a Ross procedure at Saarland University Medical Center between December 1995 and December 2023. Three hundred and fifteen patients underwent full-root replacement with or without autograft support. Twenty-three (7%) were younger than 18 years and were excluded. The cohort was divided into 3 groups: patients with aortic stenosis (AS), AR and combined disease (CD). End points included survival, freedom from reoperation and AR and aortic root dimensions; these were compared among the 3 groups. Median follow-up was 3.6 (range 0.01-26.6) years and 95% complete.

RESULTS

Overall, 292 adult patients [male 74%; mean age 39 years (SD: 10)] were analysed with (n = 209) or without autograft support (n = 83). Patients with AS (n = 79; 28%) were compared to those with AR (n = 77; 25%) and those with CD (n = 136; 50%). Valve morphology was unicuspid (n = 141; 48%), bicuspid (n = 109; 38%) or tricuspid (n = 42; 14%). Survival at 15 years was similar across the groups (AR 86%; AS 93%; CD 94%; P = 0.123). Freedom from autograft reoperation was 90% at 10 years (AR 80%; AS 95%; CD 92%; P = 0.009). With autograft support, it was 93% at 10 years (AR 90%; AS 93%; CD 95%; P = 0.179). Neither a unicuspid (hazard ratio 1.072; 95% confidence interval 0.34-3.43; P = 0.907) nor a bicuspid aortic valve (hazard ratio 0.102; 95% confidence interval 0.08-1.26; P = 0.102) was associated with reoperation.

CONCLUSIONS

Patients with AR and an unsupported root replacement do have an increased risk of reintervention, irrespective of aortic valve morphology. With autograft support, however, autograft stability is excellent, irrespective of the underlying lesion. Thus, the Ross procedure in its supported version can be offered to all haemodynamic types and valve morphologies.

CLINICAL REGISTRATION

CEP 203/19.

Impact of aortic and pulmonary artery wall histology on radicular dilatation during the Ross procedure

OBJECTIVE

In our study, we aim to explore the structural differences between the aortic root and the pulmonary artery to better understand the process of pulmonary autograft dilatation during the Ross procedure.

MATERIALS AND METHODS

We studied twenty human fetuses (aged 14-36 weeks of gestation) and four adults (one female and three males, aged 30-45 years, mean age = 37 ± 16 years). Samples of aortic root and pulmonary artery were obtained through dissection. Histological examinations, including hematoxylin-eosin, Masson's trichrome, and orcein staining, as well as immunohistochemical technique with caldesmon staining, were performed. Microscopic counting was conducted to assess the number of elastic laminae and smooth muscle cells in each arterial wall. Statistical analyses were performed using R software. Means and standard deviations were used to present central tendencies and data dispersion for elastic laminae and smooth muscle.

RESULTS

Significant histological differences were observed between the aortic root and pulmonary artery in both adults and fetuses. In fetuses, no difference was found between the two vessels in terms of elastic laminae (p = 0.26) and smooth muscle cells (p = 0.69). However, in adults, significant differences were found for elastic laminae (p < 0.001) and smooth muscle cells (p < 0.001) between the aorta and pulmonary artery.

CONCLUSIONS

The microscopic vascular structure impacts the mechanical properties of the pulmonary autograft wall and explains its observed dilatation remote from the Ross procedure due to wall stresses related to systemic pressure.

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.

The Ross procedure is an excellent operation in non-repairable aortic regurgitation: insights and techniques

The Ross procedure is the best operation to treat aortic stenosis (AS) in young and middle-aged adults. However, its role in non-repairable aortic regurgitation (AR) remains debated since many historical series have reported an increased risk of pulmonary autograft dilatation and subsequent need for reintervention in these patients. Some have attributed these findings to an unrecognized and poorly characterized inherited genetic defect that prevents adaptive remodelling of the pulmonary autograft. Herein, we review the contemporary evidence surrounding the use of the Ross procedure in young adults with AR and put forth the argument that with proper technical refinements, the Ross procedure may still be the best operation to treat these patients. We believe that by tailoring the operation to the patient's anatomy and ensuring strict postoperative blood pressure control, one can achieve excellent results with the Ross procedure, including in this challenging patient population.

Comparison of Del Nido and Blood Cardioplegia in Pediatric Patients Undergoing Surgical Repair for Congenital Heart Disease

The aim of the study is to investigate the impact of two different cardioplegia solutions, the del Nido (dN) and blood cardioplegia (BC), on postoperative troponin concentrations, vasoactive-inotrope score, and length of hospital stay in pediatric patients undergoing cardiovascular surgery for CHD. 80 subjects aged between 1 and 120 months who were scheduled for surgical repair for a CHD were prospectively enrolled in this study. Study subjects were allocated to one of the study groups using simple randomization technique as follows: The del Nido cardioplegia group (n = 40, median age 8.5 [5.5-14] months) and conventional blood cardioplegia group (n = 40, median age 11 [5-36] months). Aortic cross-clamp time and cardiopulmonary bypass time were recorded in all subjects. Troponin I and vasoactive-inotropic score, which indicates the amount of cardiovascular support by various inotropes or vasopressors, were recorded following the repair. The difference in troponin I, vasoactive-inotropic score (VIS), length of ICU stay, and length of hospital stay between the two groups was the primary outcome measure of this study. The volume of cardioplegia was significantly lower in dN group than that of the BC group (p < 0.001). Cardiopulmonary bypass time and aortic cross-clamp time were significantly shorter in subjects receiving dN cardioplegia than those receiving BC (p = 0.006, and p = 0.001, respectively). Subjects assigned to BC had higher Troponin I concentrations at postoperative 24th hour compared to subjects receiving dN cardioplegia [1.60 (0.92-2.49) ng/mL vs. 1.03 (0.55-1.83) ng/mL, p = 0.045]. VIS was also significantly higher in BC group at 24th [10 (10-13) vs. 10 (5-10), p = 0.032] and 48th hours [10 (1.5-10) vs. 0 (0-10), p = 0.005] compared to that of the dN cardioplegia group. The median extubation time was 7.5 (3.5-20.5) hours in dN cardioplegia group and 5 (4-10) hours in the BC group (p = 0.384). There were no significant differences between the groups with respect to the length of ICU stay and length of hospital stay. No mortality and no significant arrhythmias requiring medical or electrical cardioversion were noted in any of the groups. In conclusion, dN cardioplegia provides shorter aortic cross-clamp time and cardiopulmonary bypass time, and lower postoperative troponin I concentration and vasoactive-inotrope scores compared to BC in pediatric subjects undergoing surgical repair for CHD. However, lengths of ICU and hospital stay are similar in dN cardioplegia and BC groups.