[Epidemiological, clinical and echographic profile of patients operated for subvalvular aortic stenosis in the region of Sfax (Tunisia) and factors associated with postoperative recurrence: an observational study]. / Profil épidémiologique, clinique et échographique des patients opérés pour un rétrécissement aortique sous-valvulaire dans la région de Sfax (Tunisie) et facteurs associés à la récidive post-opératoire: étude observationnelle.

Subvalvular aortic stenosis is difficult to manage due to the evolutionary unpredictability of stenosis and a high recurrence rate after surgical treatment. The purpose of this study is to describe the profile of patients undergoing surgery for the treatment of aortic subvalvular stenosis and to investigate factors associated with post-operative recurrence of the subaortic obstacle. We conducted an observational study of all patients operated for subvalvular aortic stenosis, whose data were collected in the Department of Cardiology of the Sfax University Hospital between January 2010 and December 2020. The study involved 28 patients, with predominance of male sex (64.29%, n=18). At diagnosis, the mean age was 6.82 (±4.84) years and 19 patients (67.85%) had symptoms. On echocardiography, maximal subaortic gradient ≥50 mmHg was found in 23 patients (82.14%). Cardiovascular malformations associated with subvalvular stenosis were found in 16 patients (57.14%). The average age of patients at the time of surgery was 10.43 (±7.08) years. Subaortic membrane resection was the most commonly used technique (46.4%, n=13). It was associated with septal myomectomy in 8 patients (28.6%). Postoperative mortality rate was zero. Residual gradient ≥30 mmHg was reported in 8 patients (28.6%) after surgery. Recurrences were observed in 7 patients (25%) of whom 6 underwent reintervention. In multivariate analysis, only postoperative residual gradient was significantly associated with recurrence (p=0.030, OR=33.785, 95% CI: 1.398-816.754). Despite old age at diagnosis and surgery, favorable short-term outcomes were reported, but recurrences were frequent in the long term. This highlights the role of regular, perioperative and postoperative, clinical and echographic monitoring of these patients.

Surgical Repair of Secondary Subaortic Stenosis in Congenital Heart Disease Without Initial Subaortic Obstruction.

BACKGROUND: Secondary subaortic stenosis (SSS) is a rare heart disease of the left ventricular outflow tract (LVOT). It usually occurs after cardiovascular correction with or without initial left ventricular outflow tract obstruction (LVOTO). Because most patients with SSS are asymptomatic, many do not realize the need for reoperation until the obstruction worsens. Few studies suggest the characteristics and reasons of SSS without initial SAS. We conducted a retrospective study to describe the characteristics and surgical outcomes of these patients. METHODS: In this study, we examined a single-center retrospective cohort of SSS patients without initial SAS undergoing resection from 2010 to 2019. Patients are defined as secondary subaortic obstruction requiring surgery after cardiovascular correction. Demographics, perioperative findings, and clinical data were analyzed. RESULTS: Twenty-three patients had undergone secondary cardiac surgery for SSS without initial SAS during 10 years in our center. The median age at operation was 7.3 (4.0-13.5) years. In this study, the most commonly associated cardiac lesions were ventricular septal defect (VSD), atrioventricular septal defect (AVSD), patent ductus arteriosus (PDA), and coarctation arch hypoplasia (COA). The surgical techniques included membranous resection of five patients, fibromuscular resection of 17 patients, and reconstruction of the intraventricular baffle of one patient. The results of surgery in these patients are satisfied. The average LVOT gradient at the last follow up was 14.9 (7.8-26.2) mmHg. There was no operative mortality. Two patients had postoperative complications. The median follow-up period was 2.9 (1.1-4.3) years with one late death. Two patients (8.7%) had recurrence of stenosis. CONCLUSIONS: Secondary subaortic stenosis is an uncommon heart disease. The reason is related to several causes, including missed diagnosis, unnoticed abnormalities of LVOT, and further changes of geometric morphology by intracardiac surgery. The results of surgery in these patients are satisfied. However, the recurrence of stenosis is still frequent.

Long-term follow-up of subvalvular aortic stenosis in children: a single-centre experience.

OBJECTIVE: The aim of this study is to evaluate clinical and surgical outcomes of children with subaortic stenosis, to determine the risk factors for surgery and reoperation and to compare isolated subaortic stenosis and those concomitant with CHDs. METHODS: The study involved 80 children with subaortic stenosis. The patients were first classified as isolated and CHD group, and the isolated group was further classified as membranous/fibromuscular group. The initial, pre-operative, post-operative and the most recent echocardiographic data, demographic properties and follow-up results of the groups were analysed and compared. The correlation of echocardiographic parameters with surgery and reoperation was evaluated. RESULTS: There was a significant male predominance in all groups. The frequency of the membranous type was higher than the fibromuscular type in the whole and the CHD group. The median time to the first operation was 4.6 years. Thirty-five (43.7%) patients underwent surgery, 5 of 35 (14%) patients required reoperation. The rate of surgery was similar between groups, but reoperation was significantly higher in the isolated group. The gradient was the most important factor for surgery and reoperation in both groups. In the isolated group besides gradient, mitral-aortic separation was the only echocardiographic parameter correlated with surgery and reoperation. CONCLUSION: Reoperation is higher in isolated subaortic stenosis but similar in membranous and fibromuscular types. Early surgery may be beneficial in preventing aortic insufficiency but does not affect the rate of reoperation. Higher initial gradients are associated with adverse outcomes, recurrence and reoperation.

Surgical repair of subaortic stenosis resection: 10 years of single-center experience in 65 patients.

BACKGROUND: Subaortic stenosis (SAS) was a rare congenital heart disease of left ventricular outflow tract (LVOT), ranging from "isolated" lesions to "tunnel" or "diffuse" lesions. We conducted a retrospective study to describe the characteristics of patients with different lesions and analyze the risk factors for reoperation. METHODS: In this study, we examined a single-center retrospective cohort of SAS patients undergoing resection from 2010 to 2019. Patients were classified as simple lesion group (n = 37) or complex lesion group (n = 28). Demographics, perioperative findings, and clinical data were analyzed. RESULTS: The surgical effect of the two groups was significantly lower than that before the operation (p < .05). The median age at operation was 6 (3-11.8) years. There was no operative mortality. In complex lesion group, cardiopulmonary bypass time (CPB time), aortic cross-clamping time (ACC time), mechanical ventilation time, and intensive care unit (ICU) stay time were longer. The median follow-up period was 2.8 years (range: 1-3.8), with two late death. Six patients (9.2%) required reoperation due to restenosis or severe aortic insufficiency. The freedom from reoperation rates at 5 years was 66.7% for simple lesion but only 52.3% for complex lesion (p = .036). CONCLUSIONS: Although the lesions include many forms, SAS resection was still satisfactory. However, the reoperation after initial surgical treatment was not infrequent, especially in patients with complex lesion.

Palliative combined cutting and high-pressure balloon valvuloplasty in six dogs with severe, symptomatic subaortic stenosis.

INTRODUCTION/OBJECTIVES: Severe subaortic stenosis (SAS) is a congenital heart defect in dogs that often results in clinical signs and reduced survival. The objective of this study was to describe characteristics of dogs with severe, symptomatic SAS who underwent combined cutting and high-pressure balloon valvuloplasty (CB/HPBV). ANIMALS, MATERIALS, AND METHODS: Retrospective description of the clinical characteristics, CB/HPBV procedural deviations from reported methodology and outcomes in a series of six client-owned dogs with severe, symptomatic SAS. RESULTS: Breeds included two each of Newfoundland, Golden retriever, and German shepherd. Median age was 10.1 months (range: 5-72.3 months), and median weight was 25.5 kg (range: 21.8-36.4 kg). Before CB/HPBV, clinical signs were present in all dogs; four were managed for congestive heart failure (CHF). Three dogs had concurrent congenital heart disease. Median Doppler-estimated left ventricular outflow tract pressure gradient was pre-operatively 149.7 mmHg (range: 89.9-254.7 mmHg) and post-operatively 134.1 mmHg (range: 83.9-181.2 mmHg). Median aortoseptal angle was steep at 136° (range: 109-143°). Clinical improvement was documented in all dogs, based on temporary discontinuation of diuretics and/or owner-perceived reduction in clinical signs. At the time of writing, three dogs had died suddenly, one was euthanized because of recurrence of clinical signs, and one died in CHF. Median survival time was 26.4 months after procedure (range: 6.3-45.8 months). One dog remained alive at 44 months after procedure. CONCLUSIONS: Palliative CB/HPBV is a potential therapeutic option for dogs with severe, symptomatic SAS complicated by concurrent congenital heart disease, arrhythmias, or CHF.

Long-Term Outcome of Direct Relief of Subaortic Stenosis in Single Ventricle Patients.

BACKGROUND: Single ventricle patients with unrestrictive pulmonary blood flow and (potential) subaortic stenosis are challenging to manage and optimal surgical strategy is unknown. Direct relief of subaortic stenosis by enlargement of the ventricular septal defect and/or subaortic chamber has generally been replaced by a Damus-Kaye-Stansel or Norwood procedure due to concerns of iatrogenic heart block, reobstruction, or ventricular dysfunction. Studies reporting long-term outcome after the direct approach are limited. The aim of our study was to describe and analyze our experience with direct relief of subaortic stenosis in single ventricle patients. METHODS: Demographic data, characteristics, and pre-operative, operative and outcome details were collected for children undergoing direct relief of subaortic stenosis between 1989 and 2016. RESULTS: Twenty-three patients (median age: 7.4 months, range: 10 days to 5.5 years) underwent direct relief of subaortic stenosis. Complete follow-up was available for all patients (median: 15.6 years, range: 34 days to 26.3 years). Seven (30%) patients had recurrence of subaortic stenosis. One (4%) patient developed complete heart block and one patient developed moderate ventricular dysfunction. Five (50%) patients developed a (pseudo)aneurysm at site of the patch and ventriculotomy. There were two perioperative deaths. Eighty-six percent of patients underwent a successful Fontan procedure. CONCLUSIONS: Direct relief of subaortic stenosis is associated with a substantial risk of reobstruction and patch (pseudo)aneurysm formation. However, risk of heart block is low and long-term outcome is good with the majority of patients reaching Fontan completion. In our opinion, the direct approach appears to be a good and relatively simple procedure in selected cases for the treatment of subaortic stenosis.

Intraoperative transesophageal echocardiographic predictors of recurrent left ventricular outflow tract obstruction in children undergoing subaortic stenosis resection.

BACKGROUND: Intraoperative transesophageal echocardiography (iTEE) is used to assess for residual left ventricular outflow tract obstruction (LVOTO) after surgical resection of subaortic membrane causing subaortic stenosis (sub-AS). We aimed to identify the iTEE features associated with recurrence of LVOTO. METHODS: We conducted a retrospective study of children undergoing sub-AS resection from June 2006 to June 2014. Doppler assessment of the flow velocity and the anatomical features of the left ventricular outflow tract were analyzed from stored echocardiograms. Recurrent LVOTO was defined as an increase in the mean pressure gradient across the left ventricular outflow tract of > 15 mm Hg on the most recent follow-up echocardiogram from the mean pressure gradient on the predischarge echocardiogram or as doubling of the mean pressure gradient to a value ≥20 mm Hg. RESULTS: Thirty-five patients were included, with median age at surgery was 8.1 years (range: 0.7-29 years) and median follow-up was 47 months (2-91 months). Ten patients (29%) had recurrent LVOTO, which was associated with a shorter distance between the narrowest diameter of the outflow tract and the aortic valve on iTEE [median 0.59 cm (range 0.39-0.74) vs 0.98 cm (0.75-1.5), P = .03]. No patients with more than mild residual LVOTO on iTEE regressed to mild or no LVOTO on follow-up echocardiograms. CONCLUSIONS: LVOTO recurrence after sub-AS resection is common, and residual LVOTO remains the same or increases over time. Proximity of the LVOTO to the aortic valve is a risk factor for recurrent LVOTO. These findings may be useful in counseling patients and to guide the frequency of postoperative follow-up.

Subvalvular aortic stenosis: a review of current literature.

Subvalvular aortic stenosis (SAS) is one of the common adult congenital heart diseases, with a prevalence of 6.5%. It is usually diagnosed in the first decade of life. Echocardiography is the test of choice to diagnose SAS. Surgical correction is the best treatment modality, and the prognosis is usually excellent. In this review, we describe the pathophysiology, diagnosis, prognosis, and management of SAS with a focus on different pathophysiologic mechanisms, diagnostic approach, and prognosis of the disease by reviewing the current literature.

Undiagnosed mitroflow bioprosthesis deformation causing early structural valve deterioration.

Bioprosthesis are commonly used in the elderly population. Structural valve deterioration affects the long-term durability. We report an early deterioration of a Mitroflow valve caused by ring deformation and prosthetic leaflet rupture. The 69-years-old patient underwent successful redo surgery with excision of the bioprosthesis and placement of a mechanical valve.

Surgical strategies and outcomes of congenital supravalvular aortic stenosis.

BACKGROUND: Various surgical techniques have been introduced to treat supravalvular aortic stenosis (SVAS). However, there is no consensus upon the optimal approach. This study reviewed our institutional experience in the management of SVAS. METHODS: Ninety patients undergoing surgery for SVAS were identified between 2009 and 2016. Based on surgical techniques, patients were divided into three groups: McGoon repair (n = 63), Doty repair (n = 24), and Brom repair (n = 3). Median follow-up was 38.5 months (range, 4 months-7.5 years). Patient status, cumulative event-free survival rate, and risk factors for adverse clinical outcomes were assessed. RESULTS: The early mortality rate was 3.3%. There was one late death and two reinterventions. No differences were observed among three surgical groups. Event-free survival was 98.4% at 3 years and 96.5% at 5 years. Diffuse-type SVAS and a preoperative gradient greater than 60 mmHg were risk factors for adverse cardiac remodeling within 6 months post-surgery. Residual aortic stenosis was associated with male gender, preoperative aortic valve stenosis, and a preoperative peak gradient greater than 90 mmHg. Eleven patients (out of 30) who underwent concomitant pulmonary artery patching had a residual pulmonary gradient greater than 40 mmHg. CONCLUSIONS: Surgical repair of SVAS can be safely achieved using different techniques, with similar midterm mortality and reintervention rates. Higher preoperative gradient is associated with worse clinical results. Issues regarding surgical timing and concomitant pulmonary artery stenosis need to be further addressed.

Severe Valvular Aortic Stenosis and Fixed Subvalvular Aortic Stenosis: A Rare and Challenging Combination.

A 58-year-old man with a history of hypertension presented with accelerating angina. Transthoracic echocardiography revealed a thickened aortic valve with pressure gradients and an estimated aortic valve area suggestive of mild aortic stenosis. Left heart catheterization demonstrated non-significant coronary artery disease. Pressure tracings showed a high left ventricular pressure and a mean gradient across the aortic valve of 69 mmHg. Subsequent transesophageal echocardiography revealed a subvalvular aortic stenosis that was secondary to the subaortic membrane, with severe valvular aortic stenosis. The patient underwent surgical resection of the subaortic membrane followed by bioprosthetic aortic valve replacement, with resolution of his symptoms. Video 1: Transesophageal echocardiography, five-chamber view, showing the calcified aortic valve and subaortic membrane. Video 2: Transesophageal echocardiography, long-axis view, showing aliasing of the aortic flow at valvular and subvalvular levels.

Trends and Outcomes of Off-label Use of Transcatheter Aortic Valve Replacement: Insights From the NCDR STS/ACC TVT Registry.

Importance: Transcatheter aortic valve replacement (TAVR) was approved by the US Food and Drug Administration for severe aortic stenosis in patients who cannot undergo surgery and for patients at high operative risk. Use of TAVR for off-label indications has not been previously reported. Objective: To evaluate patterns and adverse outcomes of off-label use of TAVR in US clinical practice. Design, Setting and Participants: Patients receiving commercially funded TAVR in the United States are included in the Transcatheter Valve Therapy Registry. A total of 23 847 patients from 328 sites performing TAVR between November 9, 2011, and September 30, 2014, were assessed for this study. Off-label TAVR was defined as TAVR in patients with known bicuspid valve, moderate aortic stenosis, severe mitral regurgitation, severe aortic regurgitation, or subaortic stenosis. Data were linked with the Centers for Medicare & Medicaid Services for 15 397 patients to evaluate 30-day and 1-year outcomes. Exposure: Off-label use of TAVR. Main Outcomes and Measures: Frequency of off-label TAVR use and the association with in-hospital, 30-day, and 1-year adverse outcomes. Results: Among the 23 847 patients in the study (11 876 women and 11 971 men; median age, 84 years [interquartile range, 78-88 years]), off-label TAVR was used in 2272 patients (9.5%). In-hospital mortality was higher among patients receiving off-label TAVR than those receiving on-label TAVR (6.3% vs 4.7%; P < .001), as was 30-day mortality (8.5% vs 6.1%; P < .001) and 1-year mortality (25.6% vs 22.1%; P = .001). Adjusted 30-day mortality was higher in the off-label group (hazard ratio, 1.27; 95% CI, 1.04-1.55; P = .02), while adjusted 1-year mortality was similar in the 2 groups (hazard ratio, 1.11; 95% CI, 0.98-1.25; P = .11). The median rate of off-label TAVR use per hospital was 6.8% (range, 0%-34.7%; interquartile range, 3.4%-12.1%), with hospitals in the highest tertile of off-label use associated with increased 30-day adverse cardiovascular events compared with the lowest tertile. However, this difference was not observed in adjusted 30-day or 1-year outcomes. Conclusions and Relevance: Approximately 1 in 10 patients in the United States have received TAVR for an off-label indication. After adjustment, 1-year mortality was similar in these patients to that in patients who received TAVR for an on-label indication. These results reinforce the need for additional research on the efficacy of off-label TAVR use.

When Is It Better to Wait? Surgical Timing and Recurrence Risk for Children Undergoing Repair of Subaortic Stenosis.

Recurrence of subaortic stenosis (SAS) after surgery is common in children. The effects of patient characteristics and surgical timing on disease recurrence are largely unknown. We performed a retrospective study, assessing the relative effects of patient age and left ventricular outflow tract (LVOT) gradient on the need for reoperation for recurrent SAS. We included all children <20 years of age who underwent initial surgical resection of SAS at our center, January 2003-December 2013. Stratified logistic regression was performed, considering the effects of patient demographics, clinical characteristics, echocardiographic parameters, and operative technique, and clustering standard errors by surgeon. The multivariable model was used to simulate predicted probabilities of recurrent SAS for children at varying ages and baseline LVOT gradients. Sixty-three patients (38 males) underwent initial operation for SAS. Patients were followed for a median of 3.7 years (IQR 1.2-7.1). Twenty-one percent of patients (n = 13) underwent reoperation for SAS. Twelve were male. For every 10 mmHg increase in preoperative peak gradient in boys, the odds of reoperation for SAS doubled (OR 2.01, CI 1.5-2.72, p < 0.001), and for every additional 6 months of age, the odds of reoperation decreased by 14% (OR 0.86, CI 0.84-0.88, p < 0.001). Both younger age and higher preoperative outflow tract gradient are independently associated with risk of reoperation. Clinicians should consider the age and rate of LVOT gradient change-and not just the absolute gradient-in determining initial surgical timing.

[Right branch pulmonary artery stenosis with supravalvar aortic stenosis as a complication of Lecompte maneuver for tetralogy of Fallot associated with absent pulmonary valve].

The patient was diagnosed with tetralogy of Fallot associated with absent pulmonary valve syndrome and a low birth weight of 1,912 g. He suffered from respiratory distress on day 14 and received non-invasive positive pressure ventilation. At 5 months of age and 4.1 kg, he underwent intracardiac repair including right ventricular outflow repair with a monocusp patch, patch closure of the ventricular septum defect and right pulmonary transposition to the anterior of the ascending aorta following the Lecompte maneuver for airway decompression. He was subsequently discharged to home and exhibited an uneventful clinical course with non-invasive positive pressure ventilation for 5 months postoperatively. However, right pulmonary artery and supra-aortic stenosis was noted 2 years after the operation. Computed tomography (CT) and angiography showed ascending aorta strangulation by the right pulmonary artery with right ventricular outflow regurgitation. Right pulmonary artery reconstruction using polytetrafluoroethylene graft interposition and repeat right ventricular outflow repair with bicuspid hand-sewn valves was therefore performed;the postoperative course was uneventful. Pre- and post-operative management using non-invasive positive pressure ventilation and airway decompression with pulmonary artery translocation is a useful strategy in patients exhibiting symptomatic tetralogy of Fallot associated with absent pulmonary valve syndrome in the neonatal period.

Paediatric subvalvular aortic stenosis: a systematic review and meta-analysis of natural history and surgical outcome.

Sub-valvular aortic stenosis (SAS) is a common form of left ventricular outflow tract (LVOT) obstruction, which can lead to aortic valve damage. Although surgery for SAS is an accepted treatment, the timing of surgical intervention of SAS remains controversial. This review aims to establish an overview of the natural history and outcome after surgery and factors associated with prognosis in paediatric SAS patients. We searched PubMed and EMBASE for studies that reported factors that negatively affected the prognosis of patients with SAS. Studies were included if they were written in English, published between 1 January 1997 and 31 December 2012 and the mean patient age was <18 years at the time of study entry. Studies were excluded if the study size was <20 patients. A distinction was made between natural history and surgical cohorts. Twenty-four studies were included in this review, encompassing a total of 809 natural history and 1476 surgical patients. Fifty-one percent of natural history patients required surgery. After surgery, there was a substantial reoperation rate. Higher LVOT gradient and the presence of aortic regurgitation (AR) were identified as the foremost independent predictors of a worse outcome. Valve-to-membrane distance was also found to be associated with prognosis, although the results were contradictory. This systematic review underlines the importance of LVOT gradient, aortic valve-to-membrane distance and AR in surgical decision-making in paediatric SAS patients. There is need for collaborative effort to further study the optimal timing of surgery based on LVOT gradient, valve-to-membrane distance and the presence of AR.

Subvalvular Aortic Stenosis.

Obstruction of the left ventricular outflow tract (LVOT) occurs in six out of 10,000 live births. The obstruction occurs in the aortic valve level in 71 percent, in subvalvular level in 14 percent, and supravalvular level in 8 percent of cases. Subvalvular aortic stenosis (AS) can be either a fixed stenosis resulting from subaortic membrane or a dynamic stenosis because of hypertrophic cardiomyopathy. Here, we report a patient with subaortic membrane who became symptomatic in her sixth decade of life. Echocardiography is the preferred diagnostic modality. Indications for surgery include symptoms, LVOT gradient of 50 mmHg or more, and development of significant aortic regurgitation.

Surgery for simple and complex subaortic stenosis in children and young adults: results from a prospective, procedure-based national database.

OBJECTIVE: To identify the outcomes of surgically treated subaortic stenosis in a national population. METHODS: From 2000 to 2013, 1047 patients aged < 40 years underwent 1142 subaortic stenosis procedures. Of the 1047 patients, 484 (46.2%) were considered to have complex stenosis (CS) because at or before the first operation they had mitral valve (MV) disease, aortic valve disease, aortic coarctation or an interrupted aortic arch. RESULTS: The 30-day mortality was 0.7% for simple stenosis (SS), 2.3% for CS (P = .06), and 1.6% overall. Age < 1 year (P < .01), MV procedure (P = .02) and an interrupted aortic arch at the index procedure (P < .01) were risk factors for early death. Konno-type procedure early mortality was 2.4%. The 12-year survival was 97.1%, with a significant difference between SS and CS (hazard ratio [HR], 4.53; P = .02). Having MV disease alone (HR, 4.11; P = .02), MV disease plus aortic coarctation (HR, 6.73; P = .008), and age < 1 year (HR, 6.72; P < .001) were risk factors for late mortality. Freedom from subaortic reintervention overall was 92.3% and 88.5% at 5 and 12 years, respectively, much greater with CS than with SS (HR, 4.91; P < .0001). The independent risk factors for reintervention were younger age at the index procedure (HR, 0.1/y; P = .002), concomitant MV procedure (HR, 2.68; P = .019), ventricular septal defect plus interrupted aortic arch (HR, 3.19; P = .014), and ventricular septal defect plus aortic coarctation (HR, 2.41; P = .023). Undergoing a concomitant aortic valve procedure at the index procedure was protective (HR, 0.29; P = .025). CONCLUSIONS: Patients with SS had excellent outcomes. However, those with CS had worse long-term survival and freedom from reintervention, with morbidity and mortality greatest in young patients with multiple lesions. Additional evaluation in large-scale prospective studies is warranted.

A modified technique of Konno aortoventriculoplasty for redo aortic valve replacement procedures.

This article puts forward a modified technique of Konno aortoventriculoplasty for repeat procedures. After incision of the ventricular septum, this approach involves aortic valve replacement using a mechanical valved conduit, reimplantation of the coronary arteries, and graft replacement of the ascending aorta. This modification allows the removal of the diseased ascending aortic wall caused by a previous patch enlargement or poststenotic dilation.