Surgical treatment of subaortic stenosis: a seventeen-year experience

The prognostic significance of early troponin levels in patients undergoing aortic ridge surgery

Subaortic stenosis is a CHD that can lead to left ventricular hypertrophy, heart failure, and aortic valve damage if left untreated. The gold standard treatment for subaortic stenosis is septal myectomy. However, there is no clear consensus on the surgical margins required for adequate muscle resection. In this retrospective study, we reviewed the records of 83 patients who underwent subaortic stenosis surgery between 2012 and 2020 to investigate the effect of early troponin levels on prognosis. We excluded patients with additional cardiac pathologies, hypertrophic obstructive cardiomyopathy, and valvular aortic stenosis.Troponin levels were recorded in the early post-operative period, and patients were monitored for complications such as ventricular arrhythmia, left ventricular systolic dysfunction, infective endocarditis, and pacemaker implantation. The troponin levels were significantly higher in the patients who had septal myectomy. The degree of myectomy affected the risk of complications in the early post-operative period and recurrence in the later period. However, when the gradient was substantially or completely removed by myectomy, patients experienced significant symptom improvement in the early post-operative period, and their late survival was equivalent to that of healthy individuals of the same age.Our findings suggest that monitoring troponin levels in patients undergoing septal myectomy may be beneficial in predicting the risk of complications. However, further studies are needed to establish the optimal surgical technique and extent of muscle resection required for subaortic stenosis treatment. Our study adds to the existing knowledge of the benefits and risks associated with septal myectomy as a treatment option for subaortic stenosis.

Mid- and long-term outcomes after surgical correction of subaortic stenosis: a 27-year experience

OBJECTIVES

We reviewed the mid- and long-term surgical outcomes of patients with subaortic stenosis (SAS).

METHODS

Patients operated for SAS from April 1990 to August 2016 were reviewed retrospectively. Patients with major associations such as aortic arch obstruction were excluded. Time to reintervention and predictors of recurrence were assessed using Kaplan-Meier analysis, log-rank test and uni/multivariable Cox regression.

RESULTS

120 patients at a median age of 4.7 years (interquartile range 2.9, 8.1) underwent primary operation (median peak preoperative left ventricular outflow tract gradient 52.5 mmHg, interquartile range 40, 70) involving fibrous tissue excision (n = 120) with septal myectomy (93%; n = 112) as the procedure of choice.At median follow-up of 13 years (interquartile range 7, 18), freedom from reintervention at 1, 3, 5 and 10 years was 99% (95% confidence interval 94%, 99%), 94% (87%, 97%), 93% (86%, 96%) and 90% (82%, 94%), respectively. Recurrence occurred in 18% (n = 20) with 15 patients undergoing reinterventions, 13 of whom required radical reoperation. Multivariable analysis revealed higher preoperative peak left ventricular outflow tract gradient (hazard risk 1.06, confidence interval 1.03, 1.09, P < 0.001), and presence of bicuspid aortic valve (hazard risk 14.13, confidence interval 3.32, 60.1, P < 0.001) as predictors for reintervention. Mild/moderate aortic regurgitation occurred in 49% (n = 55) of patients at the most recent follow-up.

CONCLUSIONS

Reintervention for recurrent SAS is common, predicted by higher preoperative peak left ventricular outflow tract gradient, and presence of bicuspid aortic valve, and frequently involves a radical procedure. Aortic regurgitation is a major consequence of SAS, but its severity usually remains low.

CLINICAL REGISTRATION NUMBER

SCHN HREC reference number 2019/ETH02729, approved on 09 July 2019.

Subaortic Stenosis in Adult Patients With Atrioventricular Septal Defect

BACKGROUND

Patients with atrioventricular septal defects (AVSD) are at risk for development of subaortic stenosis throughout their lifetime. The early and midterm outcomes of adults with AVSD undergoing primary operation or reoperation for subaortic stenosis remain unknown.

METHODS

All patients aged 18 years or more with partial or complete AVSD who underwent operation for subaortic stenosis at our institution from 1992 to 2020 were retrospectively reviewed.

RESULTS

Nineteen patients were identified: 15 patients with partial AVSD (79%); 3 (16%) with complete AVSD; and 1 (5%) with transitional AVSD. Fifteen patients (79%) had previously corrected AVSD (median 8 years; interquartile range, 3.6-23.1) and 7 (37%) had previous repair of subaortic stenosis. The mechanism for obstruction included subaortic membrane (n = 19, 100%); septal hypertrophy (n = 11, 58%); anomalous papillary muscle, chordae, or left atrioventricular valve tissue (n = 9, 47%); and tunnel obstruction (n = 5, 26%). All patients underwent transaortic membrane resection, and septal myectomy was done in 18 patients (95%). There was no early mortality. During follow-up (median 8.3 years, maximum 28), survival was 100% at 5 years and 95% at 10 years. One patient required reintervention for subaortic stenosis 15 years after the operation at our institution.

CONCLUSIONS

Surgical correction of subaortic obstruction in adult patients with AVSD can be accomplished with low morbidity and mortality. Subaortic stenosis can appear late after the initial repair of AVSD, and these patients remain at risk for recurrence after resection.

Incidence of Reoperation After Surgical Procedure for Left Ventricular Outflow Tract Obstruction in Children and Young Adults

BACKGROUND

The common causes of subaortic left ventricular outflow tract obstruction (LVOTO) are hypertrophic cardiomyopathy (HCM) and membranous/tunnel subaortic stenosis (SAS). Reoperation after corrective surgery may be due to recurrent disease, associated congenital defects, or complications of the initial procedure. This study compares the late outcomes of young patients with HCM and SAS.

METHODS

We studied clinical, echocardiographic, and operative data of patients ≤21 years of age at the time of surgery for LVOTO between August 1963 and August 2018. We stratified patients into HCM (n = 152) and congenital SAS (n = 63) groups and compared survival and cumulative incidence of reoperation.

RESULTS

At initial repair, patients with HCM were older than patients with SAS (median [interquartile range] age, 15 [10-19] years vs 8 [5-13] years; P < .001), and patients with HCM were more symptomatic with dyspnea (P < .001), chest pain (P = .002), and presyncope/syncope (P = .005). Thirty-day mortality was 1.3% vs 0% for HCM and SAS groups. During a median follow-up of 13.1 years, survival was similar through the first 10 years; but during the second decade, patients with HCM had poorer survival (survival at 20 years, 80% vs 91% for patients with SAS; P = .007). Ten years after repair, reoperation for recurrent LVOTO was performed in 5% of patients with HCM vs 31% in those with SAS (P < .001).

CONCLUSIONS

In this surgical cohort, patients with HCM were more symptomatic preoperatively than those with SAS. Late survival of patients with SAS was superior to that of patients with HCM despite a greater need for reoperation.

Long-term outcomes after surgical repair of subvalvular aortic stenosis in pediatric patients

Objectives

Subvalvular aortic stenosis (SAS) can occur as discrete or tunnel-like obstruction of the left ventricular outflow tract and as progressive disease often leads to aortic valve regurgitation. We report our 30-year single-center experience after surgical repair of SAS.

Methods

A retrospective chart review of all patients aged &lt; 18 years, who underwent surgical repair of SAS from May 1985 to April 2020, was conducted. Mortality was cross-checked with the national health insurance database (93.8% complete mortality follow-up in April 2020). Survival and competing risks analysis were used to analyze the primary endpoints survival and incidence of reoperations.

Results

From May 1985 until April 2020 103 patients (median age 5.5 years) underwent surgical repair of SAS. Survival was 90.8% at 10 years and 88.7% at 20 and 30 years. Age &lt; 1 year at time of surgery, Shone’s complex, mitral stenosis and concomitant mitral valve surgery were associated with mortality. The cumulative incidence of reoperation for SAS was 21.6% at 10 years, 28.2% at 20 and 30 years. The incidence of reoperation for SAS did not differ between the myectomy, membrane resection and combined myectomy and membrane resection groups. The cumulative incidence of reoperation on the aortic valve was 13.5% at 20 years.

Conclusion

Recurrence rate of SAS is not to be neglected, though surgical repair of subaortic stenosis has good long-term results. Patients who needed a combined membrane resection and septal myectomy are not more prone to recurrence than patients who underwent solitaire myectomy or membrane resection.

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.

Paediatric subaortic stenosis: long-term outcome and risk factors for reoperation

 

OBJECTIVES

Surgical repair of subaortic stenosis (SAS) is associated with a substantial reoperation risk. We aimed to identify risk factors for reintervention in relation to discrete and tunnel-type SAS morphology.

METHODS

Single-centre retrospective study of paediatric SAS diagnosed between 1992 and 2017. Multivariable Cox regression analysis was performed to identify reintervention risk factors.

RESULTS

Eighty-five children [median age 2.5 (0.7-6.5) years at diagnosis] with a median follow-up of 10.1 (5.5-16.4) years were included. Surgery was executed in 83% (n = 71). Freedom from reoperation was 88 ± 5% at 5 years and 82 ± 6% at 10 years for discrete SAS, compared to, respectively, 33 ± 16% and 17 ± 14% for tunnel-type SAS (log-rank P < 0.001). Independent risk factors for reintervention were a postoperative gradient >20 mmHg [hazard ratio (HR) 6.56, 95% confidence interval (CI) 1.41-24.1; P = 0.005], tunnel-type SAS (HR 7.46, 95% CI 2.48-22.49; P < 0.001), aortic annulus z-score <-2 (HR 11.07, 95% CI 3.03-40.47; P < 0.001) and age at intervention <2 years (HR 3.24, 95% CI 1.09-9.86; P = 0.035). Addition of septal myectomy at initial intervention was not associated with lesser reintervention. Fourteen children with a lower left ventricular outflow tract (LVOT) gradient (P < 0.001) and older age at diagnosis (P = 0.024) were followed expectatively.

CONCLUSIONS

Children with SAS remain at risk for reintervention, despite initially effective LVOT relief. Regardless of SAS morphology, age <2 years at first intervention, a postoperative gradient >20 mmHg and presence of a hypoplastic aortic annulus are independent risk factors for reintervention. More extensive LVOT surgery might be considered at an earlier stage in these children. SAS presenting in older children with a low LVOT gradient at diagnosis shows little progression, justifying an expectative approach.

Congenital, acquired, or both? The only two congenitally based, acquired heart diseases

Discrete subaortic stenosis (DSS) is a type of left ventricular outflow tract obstruction whereas double-chambered right ventricle is a form of right ventricular outflow tract obstruction. Both of these cardiac malformations share lots of similar characteristics which classify them as acquired developmental heart diseases despite their congenital anatomical substrate. Both of them are frequently associated to ventricular septal defects. The initial stimulus in their pathogenetic process is anatomical abnormalities or variations. Subsequently, a hemodynamic process is triggered finally leading to an abnormal subaortic fibroproliferative process with regard to DSS or to hypertrophy of ectopic muscles as far as double-chambered right ventricle is concerned. In many cases, these pathologies are developed secondarily to surgical management of other congenital or acquired heart defects. Moreover, high recurrence rates after initial successful surgical therapy, particularly regarding DSS, have been described. Finally, an interesting coexistence of DSS and double-chambered aortic ventricle has also been reported in some cases.

A Novel Approach for Transcatheter Management of Perimembranous Ventricular Septal Defect with a Subaortic Ridge

Introduction. Surgical closure of the perimembranous ventricular septal defect (PM VSD) and resection of the subaortic ridge are the standard methods of management, but there is no definitive agreement regarding the timing of surgery. Objectives. To evaluate the safety and efficacy of the management of patients with PM VSD and subaortic ridge with or without AR via transcatheter closure of the defect and compressing the ridge against the ventricular septum using Amplatzer ductal occluder type I (ADO-I). Patients and Methods. We introduced a new approach for transcatheter management of PM VSD and subaortic ridge by closing the VSD and capturing or compressing the ridge against the interventricular septum (IVS) using the ADO-I device. Thirty-eight (9.5%) of 398 patients with a PM VSD were found to have subaortic ridge and were enrolled in this study from August 1, 2014, to February 1, 2018, at the Ibn Albitar Center for Cardiac Surgery, Baghdad, Iraq. Results. The ages and weights of patients ranged from 1.5 to 25 years and 7 to 73 kg, respectively. The male-to-female ratio was 2.2 : 1. The VSD sizes ranged from 4 to 8 mm, and the median distance of the ridge from the proximal edge of the VSD was 2.5 mm. Prior to closure, 13 patients (34.2%) had mild and mild-to-moderate aortic regurgitation (AR), and nine patients (23.7%) had mild-to-moderate left ventricular outflow tract (LVOT) obstruction. The mean AR pressure half-time increased significantly after intervention (from 385 ± 38 ms to 535 ± 69 ms (significant $P$ value, 0.001)), and the mean of the peak pressure gradient across the LVOT decreased from 33 ± 7 mmHg to 15 ± 2.4 mmHg (significant $P$ value, 0.001). Successful procedures were achieved in 33 patients (86.8%). Conclusion. Transcatheter management of patients with PM VSD and subaortic ridges with or without AR is feasible and effective.

Management of Complex Left Ventricular Outflow Tract Obstruction: A Comparison of Konno and Modified Konno Techniques

Management of complex left ventricular outflow tract obstruction (LVOTO) can be achieved with a Konno or Modified Konno procedure to enlarge the LVOT. We hypothesized that patients who undergo a Modified Konno procedure would have a higher rate of LVOT re-intervention compared to the Konno procedure. Patients who underwent a Konno or Modified Konno procedure for LVOTO at a single tertiary care center between 1990 and 2014 were retrospectively reviewed. The primary outcome was LVOT re-intervention post-discharge from index Konno or Modified Konno procedure. Cox regression and Kaplan-Meier estimates were used for time-to-event analysis of LVOT re-interventions, any unplanned re-interventions, and transplant-free survival. The study included 122 patients: 51 (41.8%) in the Konno group and 71 (58.2%) in the Modified Konno group. Median age at surgery was 8.2 (IQR 3-16) years in the Konno group and 3.9 (IQR 1.5-11) years in the Modified Konno group. Multiple left heart lesions were less prevalent in Modified Konno patients. There were 36 (29.5%) patients with LVOT re-interventions: 8 (16%) in the Konno group and 28 (39.4%) in the Modified Konno group (p = 0.01). Transplant-free survival at five years was 87.2% for the Konno group and 93.5% for the Modified Konno group. A higher rate of LVOT re-intervention was found in the Modified Konno group although the Konno and Modified Konno techniques were applied to different patient populations. This finding suggests that careful preoperative decision-making can direct therapy appropriately and that fundamental diagnosis affects procedure choice.

Long-term follow-up and outcomes of discrete subaortic stenosis resection in children

Background

Studies of long-term outcomes of discrete subaortic stenosis (DSS) are rare. Therefore, we reviewed the long-term outcomes of subaortic membrane resection in children with isolated DSS over 16 years from a single institution.

Materials and Methods

We retrospectively reviewed the records of patients (n = 27) who underwent resection of DSS between 2000 and 2017. Patients with major concomitant intracardiac anomalies were excluded. Indications for surgery were mean left ventricular outflow tract (LVOT), Doppler gradient >30 mmHg, and/or progressive aortic insufficiency.

Results

The mean age at diagnosis was 3.77 ± 3.49 years (range, 0.25-13 years) and the mean age at surgery was 6.36 ± 3.69 years (range, 1-13 years). All patients underwent resection of subaortic membrane. The mean LVOT Doppler gradient decreased from 40.52 ± 11.41 mmHg preoperatively to 8.48 ± 5.06 mmHg postoperatively (P < 0.001). The peak instantaneous LVOT Doppler gradient decreased from 75.41 ± 15.22 mmHg preoperatively to 18.11 ± 11.44 mmHg postoperatively (P < 0.001). At the latest follow-up, the peak gradient was 17.63 ± 8.93 mmHg. The mean follow-up was 7.47 ± 3.53 years (median 6.33 years; range 2.67-16 years). There was no operative mortality or late mortality. Recurrence of subaortic membrane occurred in 7 (25.92%, 7/27) patients who underwent primary DSS operation. Four (14.81%, 4/27) patients required reoperation for DSS recurrence at a median time of 4.8 years (3.1-9.1 years) after the initial repair. Risk factors for reoperation were age <6 years at initial repair. Eighteen (66.66%, 18/27) patients had AI preoperatively and progression of AI occurred in 70.37% (19/27). This included 4 (22.22%, 4/18) patients who had worsening of their preoperative AI. Short valve-to-membrane distance was found to be prognostically unfavorable. One (3.7%, 1/27) patient had an iatrogenic ventricular septal defect, and 2 (7.4%, 2/27) patients had complete AV block following membrane resection.

Conclusions

Resection of subaortic membrane in children is associated with low mortality. Higher LVOT gradient, younger age at initial repair, and shorter valve-to-membrane distance were found to be associated with adverse outcome. Recurrence and reoperation rates are high, and progression of aortic insufficiency following subaortic membrane resection is common. Therefore, these patients warrant close follow-up into adult life.

[Subaortic diaphragm surgery]

Le diaphragme sous aortique se caractérise par une certaine latence clinique et une faible morbi-mortalité. La chirurgie reste le traitement de choix malgré un réel risque de récurrence à long terme. Nous rapportons 18 patients opérés entre Avril 1994 et Mars 2011 pour diaphragme sous aortique d’âge moyen de 18,1±9,7 ans avec 11 patients de sexe masculin. Le diaphragme était de nature fibreuse chez 13 patients et fibro-musculaire chez 5 patients. Tous les patients ont été opérés par résection de diaphragme associée à une myectomie, une plastie aortique, une fermeture de communication interventriculaire et une ligature de canal artériel perméable respectivement chez 3, 3, 2 et 2 patients. La Mortalité opératoire était nulle et sans aucun cas de trouble de conduction postopératoire. Le suivi a duré en moyenne 44,3±36,8 mois sans aucun décès tardif. Deux patients ont présenté une récidive de diaphragme qui a nécessité une réopération avec bonne évolution. La tendance actuelle dans la chirurgie du diaphragme se fait vers des interventions précoces et des résections plus extensives. Cependant, le risque de récidive impose une surveillance échographique systématique et rapprochée.

Echocardiography as a Predicting Method in Diagnosis, Evaluation and Assessment of Children with Subvalvar Aortic Stenosis

BACKGROUND:

Obstruction to the left ventricular outflow of the heart may be above the aortic valve (5%), at the valve (74%), or in the subvalvar region (23%). These anomalies represent 3 to 6% of all patients with congenital heart defects (CHD), and it occurs more often in males (male-female ratio of 4:1).

AIM:

The purpose of this study was to determine the sensitivity and specificity of transthoracic echocardiography in diagnosis of discrete subaortic membrane, to determine convenient time for surgical intervention, and for identifying involvement of the aortic valve by subaortic shelf.

MATERIAL AND METHODS:

A retrospective review of the medical records and echocardiograms of 18 patients [14 male (77%) and 4 female (23%)] with discrete subaortic membrane, aged 11 month to 12 years, with mean age of 5 years and 3 month, diagnosed at the Pediatric Clinic in Prishtina, during the period September, 1999 and December, 2010 were done.

RESULTS:

Four patients, in neonatal age were operated from critical coarctation of the aorta and, initial signs of congestive heart failure were presented. 2 of them were operated in Belgrade, Serbia and 2 in Lausanne, Switzerland.

CONCLUSION:

In all presented patients bicuspid aortic valve was noted, but none of them subaortic membrane was registered.

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.

Severe mitral regurgitation due to anterior mitral leaflet perforation after surgical treatment of discrete subaortic stenosis

Congenital subvalvular aortic stenosis may be associated with anomalies of the mitral valve. In this case, we present a patient with severe mitral valve regurgitation due to a perforation in the anterior mitral leaflet detected 4 months after an operation for relief of subaortic stenosis. A 10-year-old male patient who was operated for subvalvular aortic stenosis in another clinic was admitted to our hospital, and transthoracic echocardiography revealed severe mitral valve regurgitation due to a defect that was demonstrated at the anterior valve leaflet. The perforated area at the mitral valve zone A1 was repaired with a PTFE patch. The patient was successfully operated for the mitral valve perforation and the postoperative course was uneventful. In our case, the perforation in the anterior mitral leaflet implies a possible implementation of inappropriate surgical technique which necessitated a second surgical intervention after the initial operation.

Modified Konno operation for diffuse subaortic stenosis

The modified Konno operation is designed to provide relief of diffuse subaortic stenosis, while preserving the native aortic valve. The aorta and the right ventricular infundibulum are opened. The upper part of the subaortic stenosis is incised through the aortic orifice. The conal septum is incised and the septotomy is extended across the stenotic area. The obstructive tissue is removed (mainly from the left-handed rim of the septotomy) and the conal septum is enlarged with a prosthetic patch. The aorta is closed and the right ventricular infundibulum is enlarged. Early and late mortality rates are low. Potential morbidity (complete heart block, residual ventricular septal defect, iatrogenic aortic insufficiency, right ventricular outflow tract obstruction) should be minimized by a careful surgical technique. The modified Konno operation is indicated in patients with diffuse subaortic stenosis and a normal aortic orifice; this includes patients with severe forms of hypertrophic obstructive cardiomyopathy and children with tunnel subaortic stenosis and a normal aortic orifice; the modified Konno procedure provides long-lasting relief of the obstruction. In patients with tunnel stenosis and a borderline-sized aortic annulus, residual obstruction may develop at the valvar level and need reoperation; the modified Konno operation can, however, delay aortic valve replacement.

Fixed subaortic stenosis: a clinical dilemma for clinicians and patients

Subaortic stenosis carries considerable morbidity and mortality. In most cases, patients have an underlying left ventricular outflow tract morphology that promotes turbulence at the outflow tract, which induces the development of subaortic fibromuscular tissue. A subset of patients will progress to develop severe stenosis and aortic regurgitation, but it has been difficult to determine which patients are at risk. While resection of the subaortic tissue improves immediate outcome, many patients have recurrence of both stenosis and regurgitation, questioning the efficacy of surgical intervention in asymptomatic patients. This review article describes the current understanding of the etiology, treatment, and prognosis of subaortic stenosis.

Evaluation of subvalvular aortic stenosis in children: a 16-year single-center experience

Subvalvular aortic stenosis accounts for 1-2 % of all congenital heart disease and for 8-20 % of cases of left-ventricular outflow tract (LVOT) obstruction in children. Recurrence of subaortic stenosis (SAS) is not uncommon after surgical management. This study was performed to investigate the clinical and surgical outcomes and to estimate the predictability of recurrences of SAS. Seventy-nine patients age 3-21 years with SAS between 1994 and 2010 were reviewed. Fifty-one patients had discrete SAS, whereas the remaining 15 patients had fibromuscular ridge-type SAS. Mean follow-up time without surgery was 22 months (range of 1-94). Forty-one patients with a diagnosis of SAS underwent surgery. Recurrence rates were 22.7 % (15 patients), and these patients developed SAS at a mean of 4.7 years follow-up. We performed second surgical membrane resection in only 1 patient. The risk of recurrence of SAS was only linked to higher preoperative LVOT gradient. Twenty-three patients had no aortic regurgitation (AR) at preoperative echocardiography. Of these, 39.1 % had trivial, 8.7 % had mild, and 8.7 % had moderate AR after surgery; there was no significant AR. We conclude that surgical intervention was required most of the time in patients with SAS, and surgical outcomes was excellent even if there were associated cardiac defects. The risk of recurrences was higher, especially in patients with higher initial LVOT gradients, although a second surgery was rarely necessary in these patients.

Modified Konno procedure: surgical management of tunnel-like left ventricular outflow tract stenosis

Left ventricular outflow tract stenosis represents 1-2 % of all congenital anomalies. In particular, tunnel-like left ventricular stenosis which is one type of fixed left ventricular outflow stenosis requires aggressive surgery to reduce the left ventricular outflow gradient. The purpose of the modified Konno procedure is to release fixed left ventricular outflow tract stenosis while preserving the native aortic valve and its function. Although the clinical results of the modified Konno procedure are acceptable, it is necessary to precisely understand this procedure and the anatomy of the left ventricular outflow tract in order to avoid complications.

Surgical outcome of discrete subaortic stenosis in adults: a multicenter study

BACKGROUND

Discrete subaortic stenosis is notable for its unpredictable hemodynamic progression in childhood and high reoperation rate; however, data about adulthood are scarce.

METHODS AND RESULTS

Adult patients who previously underwent surgery for discrete subaortic stenosis were included in this retrospective multicenter cohort study. Mixed-effects and joint models were used to assess the postoperative progression of discrete subaortic stenosis and aortic regurgitation, as well as reoperation. A total of 313 patients at 4 centers were included (age at baseline, 20.2 years [25th-75th percentile, 18.4-31.0 years]; 52% male). Median follow-up duration was 12.9 years (25th-75th percentile, 6.2-20.1 years), yielding 5617 patient-years. The peak instantaneous left ventricular outflow tract gradient decreased from 75.7±28.0 mm Hg preoperatively to 15.1±14.1 mm Hg postoperatively (P<0.001) and thereafter increased over time at a rate of 1.31±0.16 mm Hg/y (P=0.001). Mild aortic regurgitation was present in 68% but generally did not progress over time (P=0.76). A preoperative left ventricular outflow tract gradient ≥80 mm Hg was a predictor for progression to moderate aortic regurgitation postoperatively. Eighty patients required at least 1 reoperation (1.8% per patient-year). Predictors for reoperation included female sex (hazard ratio, 1.53; 95% confidence interval, 1.02-2.30) and left ventricular outflow tract gradient progression (hazard ratio, 1.45; 95% confidence interval, 1.31-1.62). Additional myectomy did not reduce the risk for reoperation (P=0.92) but significantly increased the risk of a complete heart block requiring pacemaker implantation (8.1% versus 1.7%; P=0.005).

CONCLUSIONS

Survival is excellent after surgery for discrete subaortic stenosis; however, reoperation for recurrent discrete subaortic stenosis is not uncommon. Over time, the left ventricular outflow tract gradient slowly increases and mild aortic regurgitation is common, although generally nonprogressive over time. Myectomy does not show additional advantages, and because it is associated with an increased risk of complete heart block, it should not be performed routinely.

Surgical management of subaortic stenosis

A 63-year-old male patient with subaortic stenosis (Pmax 105 mmHg, Pmean 55 mmHg) and an aneurysm of the ascending aorta was referred to our hospital due to progressive angina pectoris. Transesophageal echocardiography demonstrated high and turbulent subaortic flow velocities. A calcified subaortic membrane was identified. The membrane was removed and the aneurysm was treated with a Bentall procedure. The patient recovered smoothly from surgery and was doing well 6 months after discharge.

Discrete subaortic stenosis 37 years after repair of a ventricular septal defect

Discrete subaortic stenosis (DSS) is uncommon in adults after surgical correction of congenital heart defects. There are only a few published reports on the occurrence of DSS in adults. We present an adult case with DSS after repair of a ventricular septal defect (VSD). The case was a 44-year old female patient who underwent VSD closure at 7 years of age. Thirty-seven years later, she presented with congestive heart failure associated with severe subaortic membranous stenosis and atrial fibrillation (AF) that required surgical repair. We report successful surgical treatment of this adult patient with DSS and AF 37 years after repair of a VSD.

Long-Term Outcome of Patients With Isolated Thin Discrete Subaortic Stenosis Treated by Balloon Dilation

Background—

Transluminal balloon tearing of the membrane in a thin discrete subaortic stenosis is an alternative to membrane surgical resection. However, the long-term outcome of patients with isolated thin discrete subaortic stenosis treated by transluminal balloon tearing remains unknown.

Methods and Results—

This 25-year study describes findings from 76 patients with isolated thin discrete subaortic stenosis who underwent percutaneous transluminal balloon tearing of the membrane and were followed up for a mean period of 16±6 years. The age at presentation had a wide range (2–67 years). The mean age at treatment was 19±16 years. Immediately after treatment, the subvalvular gradient decreased from 70±27 to 18±12 mm Hg ( P <0.001). No significant postprocedural aortic regurgitation was observed. After a mean follow-up time of 16±6 years, 11 patients (15%) developed restenosis, 3 patients (4%) progressed to muscular obstructive disease, and 1 patient (1.3%) developed a new distant obstructive membrane. Twelve patients (16%) were redilated at a mean of 5±3 years after their first treatment, and 4 patients (5%) underwent surgery at a mean of 3±2 years after their first treatment. Fifty-eight patients (77%) remained alive and free of redilation or surgery at follow-up. Larger annulus diameter and thinner membranes were independent factors associated with better long-term results.

Conclusions—

Most patients (77%) with isolated thin discrete subaortic stenosis treated with transluminal balloon tearing of the membrane had sustained relief at subsequent follow-ups without restenosis, the need for surgery, progression to muscular obstructive disease, or an increase in the degree of aortic regurgitation.

Secondary subaortic stenosis after patch closure of subarterial ventricular septal defect

Subaortic stenosis usually occurs without a previous heart operation, however, it can occur after heart surgery as well, with a condition known as a secondary subaortic stenosis (SSS). SSS has been reported after surgical repair of several congenital heart defects. There are only a few recorded cases of SSS after repair of ventricular septal defect (VSD). Here we report a rare case of SSS that occurred 3 years after surgical repair of subarterial VSD. A follow-up echocardiogram is essential for detecting SSS caused by the newly developed subaortic membrane in patients who had cardiac surgery.

Transthoracic echocardiography does not reliably predict involvement of the aortic valve in patients with a discrete subaortic shelf

BACKGROUND

A discrete subaortic membrane cannot only cause left ventricular outflow tract obstruction, but can grow onto the aortic valve leaflets. The late finding of this encroachment is aortic valve insufficiency or stenosis. Echocardiography is used to follow the progression of outflow tract obstruction, but its ability to show subaortic membrane encroachment onto the aortic valve is unclear. The purpose of this study is to determine the sensitivity and specificity of echocardiography for diagnosing whether a discrete subaortic membrane involves the aortic valve.

METHODS

A pre-operative determination of aortic valve involvement by a discrete subaortic membrane was obtained by review of the official pre-operative echocardiogram reading and a retrospective blinded review of the pre-operative echocardiogram by an independent echocardiographer. These findings were compared to the intra-operative findings.

RESULTS

A total of 48 consecutive patients underwent primary resection for isolated discrete subaortic membrane between October, 1995 and May, 2006. The pre-operative and blinded readings both predicted a statistically lower rate of aortic valve involvement - 35% in 11 of 31 patients and 31% in 10 of 31 patients, respectively - than found at surgery - 65% in 31 of 48 patients. The sensitivity and specificity of pre-operative echocardiography to diagnose aortic valve involvement is 35% and 76%. Overall survival was 100%. There were no strokes, re-operations for bleeding or wound infections, or need for a pacemaker.

CONCLUSION

Echocardiography is not sensitive in assessing whether a discrete subaortic membrane involves the aortic valve. Since the morbidity and mortality for discrete subaortic membrane resection is negligible, resection may be indicated at the time of diagnosis to minimise aortic valve impairment.

Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: outflow tract obstruction, coarctation of the aorta, tetralogy of Fallot, Ebstein anomaly and Marfan's syndrome

With advances in pediatric cardiology and cardiac surgery, the population of adults with congenital heart disease (CHD) has increased. In the current era, there are more adults with CHD than children. This population has many unique issues and needs. Since the 2001 Canadian Cardiovascular Society Consensus Conference report on the management of adults with CHD, there have been significant advances in the field of adult CHD. Therefore, new clinical guidelines have been written by Canadian adult CHD physicians in collaboration with an international panel of experts in the field. Part II of the guidelines includes recommendations for the care of patients with left ventricular outflow tract obstruction and bicuspid aortic valve disease, coarctation of the aorta, right ventricular outflow tract obstruction, tetralogy of Fallot, Ebstein anomaly and Marfan's syndrome. Topics addressed include genetics, clinical outcomes, recommended diagnostic workup, surgical and interventional options, treatment of arrhythmias, assessment of pregnancy risk and follow-up requirements. The complete document consists of four manuscripts that are published online in the present issue of The Canadian Journal of Cardiology. The complete document and references can also be found at www.ccs.ca or www.cachnet.org.

Long-term Outcome and Risk of Heart Block After Surgical Treatment of Subaortic Stenosis

Although mortality following repair of subaortic obstruction is low, aggressive resection may increase morbidity. We sought to evaluate outcomes and risk of atrioventricular heart block (AVB) after subaortic resection in the current era. Simple obstruction was defined as a discrete subaortic membrane and complex as multilevel or diffuse narrowing. Limited resection included membranectomy and limited myomectomy. Aggressive resection included Konno, modified Konno, and Ross. Specified variables were obtained from a chart review. The 185 consecutive patients (1991-2008) ranged in age from 1 day to 21.8 years (5.1 ± 5.1 years) with 2 early and 4 late deaths. Actuarial survival was 97%, 95%, and 95% at 1, 5, and 10 years, respectively. Reoperations were required in 29 of 185 patients (15.7%); 2 required a third operation (1%). Freedom from reoperation in all patients was 97%, 83%, and 73% at 1, 5, and 10 years, respectively. Accessory mitral valve tissue ( P < .001) and age <3 months ( P = .004) predicted the need for reoperation. Transient or permanent high-degree AVB was documented in 33 of 185 patients (17.8%). Complex anatomy ( P = .01) and aggressive resection ( P < .001) increased the risk of acquiring AVB. The AVB was permanent in 21 of 185 (11.4%) patients, and pacemaker implantation was undertaken in 20 of 185 (10.8%) patients. Complex anatomy ( P = .04) and modified Konno procedure ( P = .03) increased the risk of acquiring a pacemaker. Aggressive resection lowered the frequency of recurrence but increased the risk of AVB. When aggressive resection is considered for long-term relief of subaortic obstruction, the risk of reobstruction must be balanced with the risk of AVB and the need for pacemaker implantation.

Severe subaortic stenosis that progressed over a 12-year period after cardiac surgery

A 12-year-old girl who had undergone cardiac surgery for ventricular septal defect (VSD), atrial septal defect (ASD), and patent ductus arteriosus (PDA) in infancy was referred to our institution for fatigue and excessive sweating. Transthoracic and transesophageal echocardiographic studies revealed tunnel-type subaortic stenosis with aortic valvular stenosis, for which she underwent aortic valve replacement and myomectomy of left ventricular outflow tract. Progression of subaortic stenosis should be considered in patients with only mild aortic valve stenosis after previous cardiovascular surgery. Echocardiography contributed significantly to making the diagnosis and therapeutic decision in our patient.

Prevalence and Associated Risk Factors for Intervention in 313 Children With Subaortic Stenosis

BACKGROUND

We sought to determine the prevalence of intervention and associated factors in children presenting with subaortic stenosis. We also investigated whether a protocol adopted in 1994 of early subaortic resection at a preoperative mean systolic gradient across the left ventricular outflow tract (LV gradient) greater than 30 mm Hg was supported by longitudinal outcomes.

METHODS

Record review of all children (n = 313) diagnosed with subaortic stenosis was conducted between 1975 and 1998 at our institution. Cox proportional hazard models determined the prevalence and associated factors for initial subaortic resection. Mixed models of serially obtained echocardiographic data (n = 933) established longitudinal LV gradient trends and identified factors associated with more rapid LV gradient progression.

RESULTS

Median age at presentation was 8 months. Freedom from initial subaortic resection was 40% at 16 years from diagnosis. Earlier progression to subaortic resection was associated with patient characteristics at presentation, including a higher initial LV gradient (p < 0.001), larger aortic annulus z-score (p = 0.005), smaller body surface area (p < 0.001), and smaller mitral annulus z-score (p = 0.003). Initial resection was also associated with a faster rate of LV gradient progression (p = 0.003). Factors determining the increased rate of LV gradient progression included an initial LV gradient greater than 30 mm Hg (p < 0.001), initial aortic valve thickening (p = 0.003), and attachment of subaortic stenosis to the mitral valve (p = 0.003). Worse aortic regurgitation grade with time was also associated with an initial LV gradient greater than 30 mm Hg (p < 0.001).

CONCLUSIONS

Subaortic resection should be delayed until the LV gradient exceeds 30 mm Hg because most children with an initial LV gradient less than 30 mm Hg have quiescent disease.

Surgery for subvalvar aortic stenosis - resection of discrete subvalvar aortic membrane

Discrete subvalvar aortic membrane is characterized by a fibromuscular shelf located at the area of aortomitral continuity with the extension toward the interventricular septum. As compared to other congenital heart defects, discrete subvalvar aortic membrane is virtually never recognized in early infancy, but appears to be an 'acquired' lesion, typically seen in patients with a more acute angle between the long axis of the left ventricle and the aorta. This angulation leads to imbalance in shear forces, which causes the proliferation of tissue that forms the membrane. The surgical intervention is considered when the gradient across the left ventricular outflow tract is 30 mmHg or more. Surgery is also advocated in infants and children in the presence of aortic regurgitation even when there is no significant gradient. The circumferential excision of the fibrous ridge with septal myectomy is safe and provides efficient relief of obstruction. Aggressive resection of all structures causing flow turbulence and removal of pathological tissue from the valve leaflets might prevent development or progression of aortic regurgitation and might eliminate the substrate for recurrent obstruction. Nevertheless, recurrence still remains a problem, especially in the presence of a predisposing associated congenital heart defect.

Correction of discrete subaortic stenosis with abnormal chordae tendineae

The case of a 52-year-old woman with subvalvular aortic stenosis and aortic regurgitation is presented. Mitral regurgitation was associated, due to insertion of two abnormal chordae tendineae at the apex of the anterior papillary muscle and at the free border of the subvalvular membranous annulus. This abnormality displaced the anterior papillary muscle, thus applying a traction at the mitral leaflet. The patient was operated on through a valve-sparing approach, in which the discrete subaortic stenosis was removed through aortotomy and the ectopic chordae were excised. Suture mitral annuloplasty completed the procedure. Aortic and mitral insufficiency almost disappeared at follow-up. From the examination of this case and from a review of pertinent literature it emerges that in event of similar complex congenital abnormalities without intrinsic valve disease, a conservative approach should be chosen so that valve replacement can be avoided.

Surgical treatment of subaortic obstruction in adolescent and adults: long-term follow-up

Subaortic stenosis (SAS) is a wide spectrum of anatomical derangements ranging from a discrete fibrous membrane to tortuous fibrous tunnel with or without aortic annulus hypoplasia. We have reviewed 88 patients undergoing surgery for SAS over a 15-year period. There were 47 male and 41 female patients with a mean age of 19.8 +/- 10.6 years (range 11 to 39). Fifty-eight patients had discrete subaortic membrane, and 30 patients had diffuse tunnel subvalvular stenosis. The mean systolic pressure gradients were found to be 86.5 +/- 31.4 mmHg (range 48 to 145 mmHg). Ten patients had mild and 13 patients had moderate-to-severe aortic insufficiency (AI) preoperatively. Nine patients had bicuspid aortic valve. Forty patients (45.4%) had associated cardiac lesions. Isolated membranectomy was performed in six patients. Membranectomy associated with septal myectomy was done in 52 patients. Fifteen patients of them associated hypoplasia of the aortic orifice necessitated aortic valve replacement (AVR) using the Konno-Rastan procedure. Fifteen patients with tunnel SAS and normal aortic valves underwent a combined approach for valve sparing, a modified Konno procedure with patch septoplasty. Also eight patients required AVR because of the severity of AI and five patients aortic reconstruction procedures. Aortic commissurotomy was performed to relief of stenosis in four patients. There were three early deaths (3.4%) and one late death (1.1%) all after the Konno-Rastan procedure. Eight patients (9.1%) had permanent conduction abnormalities. Postoperative left ventricle-aorta gradient was significantly decreased at early postoperative period (p < 0.001) and ranged from 10 to 25 mmHg (mean 14.1 +/- 4.3). Fourteen patients (16.5%) were reoperated for recurrent obstruction or progression of AI. The mean reoperation interval was 4.4 +/- 1.7 years (range 2 to 8 years). Five-year reoperation-free survival was 88.0 +/- 3.6% and 12.5-year reoperation-free survival was 75.5 +/- 7.0%. Our results of aggressive surgical approach of subvalvular aortic stenosis produces relief of obstruction and frees the valve leaflets, significantly reducing associated AI with long-term survival and long-term adequate relief of left ventricular outflow tract obstruction.

Surgical management of tunnel-like subaortic stenosis via ventricular septal defect in a patient with the interrupted aortic arch

A 24-day-old male with interrupted aortic arch (type B), ventricular septal defect, and tunnel-like subaortic stenosis underwent a one-stage surgical treatment. The operative procedure comprised reconstruction of the aortic arch, transatrial excision of the subaortic fibromuscular tissue via the ventricular sepatal defect, and patch closure of the defect. The patient tolerated the procedure well and the postoperative echocardiography demonstrated a residual pressure gradient across the left ventricular outflow tract of 20 mmHg. Our result suggests that the transatrial surgical management of subaortic stenosis via the ventricular sepatal defect produces a safe and promising surgical option.

Surgical correction of subaortic stenosis via right ventriculotomy and septal resection in a dog

After 2 years of medical management with a beta-adrenoreceptor blocking agent, a 30-month-old castrated male Golden Retriever with subaortic stenosis was treated surgically because of progression of its condition. In an attempt to achieve complete relief of the left ventricular outflow obstruction, a modified Konno procedure consisting of right ventriculotomy and septal myectomy from the infundibular portion of the right ventricle was performed; this combination of procedures allowed wide resection of the septal portion of the left ventricular outflow obstruction. Two years after surgery, the mass of the dog's left ventricle had decreased and the peak calculated pressure gradient across the aortic valve had decreased to 40 mm Hg, compared with a preoperative value of 240 mm Hg; at that evaluation, the dog had gained weight and was able to play normally. It is suggested that use of this modified approach to the outflow tract may have a positive effect on long-term survival time in dogs with subaortic stenosis.

Discrete subaortic stenosis: incidence, morphology and surgical impact of associated subaortic anomalies

BACKGROUND

The association between discrete subaortic stenosis and other subaortic anomalies is a well known but rarely reported occurrence. The aim of this study is to define the incidence, morphology, and surgical impact of associated anomalies of the left ventricular outflow tract in children operated on for discrete subaortic stenosis.

METHODS

Between 1994 and 2000, 45 consecutive children were operated on for discrete subaortic stenosis. Patients were divided in two groups according to the obstructive lesion detected by echocardiography.

RESULTS

A localized shelf was found as an isolated lesion in 31 patients (group A), whereas additional subaortic anomalies were found in 14 cases (31%) and were multiple in 5 cases (group B). The anomalies included anomalous septal insertion of mitral valve (7 cases); accessory mitral valve tissue (2 cases); anomalous papillary muscle (2 cases); anomalous muscular band (8 cases); and muscularization of the anterior mitral valve leaflet (1 case). Cardiopulmonary bypass and aortic cross-clamping times were significantly shorter in group A. There were no operative deaths nor major complications or deaths during follow-up. A gradient of 15 mm Hg or more was found at follow-up in 5 cases whereas aortic regurgitation was estimated to be not clinically significant in all but 1 patient. Six cases of recurrent subaortic stenosis were found in our series, 3 of them with other subaortic anomalies.

CONCLUSIONS

This study shows that discrete subaortic stenosis can often be associated with other subaortic abnormalities. Surgical treatment of these anomalies produces excellent early and mid-term relief of obstruction without any increase in mortality and morbidity.