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

Contemporary Clinical Characteristics, Imaging, Management, and Surgical and Nonsurgical Outcomes of Adult Patients With Subaortic Stenosis

BACKGROUND

Subaortic stenosis (SAS) is characterized by a fibromuscular membrane located just below the aortic valve, causing fixed outflow tract obstruction. There is a paucity of studies evaluating this condition. This cohort study reviewed the contemporary characteristics and outcomes of SAS in adult patients in a single large referral center.

METHODS AND RESULTS

We retrospectively studied adult patients with SAS evaluated at our center during 2011 to 2022. The primary outcome was all-cause mortality and heart failure hospitalizations during follow-up, with secondary end points including recurrence of SAS and repeat surgery after initial SAS surgery. Among 484 patients with SAS, key characteristics included mean age 55±18 years, 67.5% female, left ventricular outflow tract peak velocity 352±140 cm/s and gradient 57±40 mm Hg, left ventricular ejection fraction 60%±14%, 54.8% had prior SAS surgery, and 45.1% had surgery during follow-up. Over a median follow-up of 5.5 (1.5-12.3) years, 11.5% (n=56) died, 6.8% (n=33) had heart failure hospitalizations, 8.0% (n=39) experienced SAS recurrence, and 14 (5.9%) underwent repeat SAS surgery. Multivariable analyses identified older age per 10-years (hazard ratio [HR], 1.37 [95% CI, 1.12-1.68]) and baseline New York Heart Association class (HR, 2.48 [95% CI, 1.54-3.99]) to be statistically significantly associated with the primary end point; higher body mass index, New York Heart Association class, and peak left ventricular outflow tract gradient were also statistically significantly associated with SAS recurrence and redo surgery.

CONCLUSIONS

Almost half of patients with SAS had surgery in the past or during follow-up, and a significant minority had mortality or morbidity events during follow-up. Identified prognosticators warrant further research to guide management.

Adults with congenital heart disease: what every cardiologist should know about their care

As patients with congenital heart disease (CHD) continue to enjoy longer lives, non-congenital cardiologists and other healthcare professionals are increasingly encountering them in their practice and are challenged by their specific needs. Most under- and post-graduate medical training tends to overlook this common pathology, resulting in insufficient awareness of post-repair or post-palliation residual lesions and sequelae from previous interventions. In a strive towards improving the quality of care for this ever-growing cardiovascular patient cohort, it is prudent to outline the areas of concern and specific management needs pertaining to adult patients with CHD and share it with non-CHD professionals. The purpose of this paper is to offer essential guidance to physicians, including cardiologists, when they encounter a patient with CHD in a non-congenital healthcare setting.

Management of the mitral valve in thoracoscopic trans-mitral myectomy for hypertrophic obstructive cardiomyopathy

Objective

This study aimed to compare clinical outcomes of different mitral valve (MV) management methods in thoracoscopic transmitral myectomy (TTM) and guide surgeons' decision making for hypertrophic obstructive cardiomyopathy (HOCM).

Methods

Seventy-three consecutive patients (41 females; mean age, 53.7 ± 13.6 years) with HOCM who underwent TTM between January 2019 and October 2022 were enrolled and divided into 3 groups according to MV surgical strategy. Clinical outcomes were analyzed and compared among the groups.

Results

None of the patients experienced postoperative residual left ventricular outflow tract obstruction. Percentages of patients with mitral regurgitation (MR) grade ≥3+ (57.5% vs 1.4%) and systolic anterior motion (95.9% vs 2.7%) were significantly decreased postoperatively (P < .001 for both). The preoperative anterior mitral leaflet length was longer in patients in the anterior mitral leaflet direct reattachment group (median, 2.9 cm [interquartile range (IQR), 2.7-3.3 cm] vs 2.7 [IQR, 2.4-2.9 cm]; P = .018), but the postoperative coaptation length was shorter (mean, 8.3 ± 2.1 mm vs 11.1 ± 3.8 mm; P = .038). After a median echocardiography follow-up of 11.8 months, the left ventricular outflow tract gradient (LVOTG) and mitral regurgitation grades remained significantly improved in all 3 groups (P < .05 for all).

Conclusions

Total TTM in selected patients is safe and effective, and all 3 MV management strategies can significantly reduce the LVOTG while improving MR. Mitral valvuloplasty is the preferred initial management strategy over valve replacement except in the scenario of irreparable intrinsic MV disease and valvuloplasty failure.

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.

Subvalvular Aortic Stenosis: Learning From Human and Canine Clinical Research

Subvalvular aortic stenosis (SAS) is the most common congenital heart disease (CHD) in dogs and is also prevalent in human children. A fibrous ridge below the aortic valve narrows the left ventricular outflow tract (LVOT) and increases blood flow velocity, leading to devastating side effects in diseased patients. Due to the similarities in presentation, anatomy, pathophysiology, cardiac development, genomics, and environment between humans and dogs, canine SAS patients represent a critical translational model of human SAS. Potential adverse outcomes of SAS include arrhythmias, left-sided congestive heart failure, endocarditis, exercise intolerance, syncope, and sudden cardiac death. The greatest divergence between canine and human SAS clinical research has been the standard of care regarding treatment of these outcomes, with pharmacological intervention dominating best practices in veterinary medicine and surgical intervention comprising the standard practice for human SAS patients. Regardless of the species, the field has yet to identify a treatment option to prevent disease progression or permanently remove the fibrous ridge, but historical leaps in SAS research support a continued translational approach as the most promising method for achieving this goal.

Now You See Me Now You Don't: Subaortic Membrane Causing a Diagnostic Dilemma

Subaortic stenosis secondary to subaortic membrane is the second most common form of left ventricular outflow tract obstruction. We present the case of a 70-year-old male patient who presented with a 6-week history of progressive signs of heart failure. Multimodality imaging was required to confirm the presence of a subaortic membrane. (Level of Difficulty: Beginner.).

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.

Significance of aortoseptal angle anomalies to left ventricular hemodynamics and subaortic stenosis: A numerical study

PURPOSE

Discrete subaortic stenosis (DSS) is an obstructive cardiac disease caused by a membranous lesion in the left ventricular (LV) outflow tract (LVOT). Although its etiology is unknown, the higher prevalence of DSS in LVOT anatomies featuring a steep aortoseptal angle (AoSA) suggests a potential role for hemodynamics. Therefore, the objective of this study was to quantify the impact of AoSA steepening on the LV three-dimensional (3D) hemodynamic stress environment.

METHODS

A 3D LV model reconstructed from cardiac cine-magnetic resonance imaging was connected to four LVOT geometrical variations spanning the clinical AoSA range (115°-160°). LV hemodynamic stresses were characterized in terms of cycle-averaged pressure, temporal shear magnitude (TSM), and oscillatory shear index. The wall shear stress (WSS) topological skeleton was further analyzed by computing the scaled divergence of the WSS vector field.

RESULTS

AoSA steepening caused an increasingly perturbed subaortic flow marked by LVOT flow skewness and complex 3D secondary flow patterns. These disturbances generated WSS overloads (>45% increase in TSM vs. 160° model) on the inferior LVOT wall, and increased WSS contraction (>66% decrease in WSS divergence vs. 160° model) in regions prone to DSS membrane formation.

CONCLUSIONS

AoSA steepening generated substantial hemodynamic stress abnormalities in LVOT regions prone to DSS formation. Further studies are needed to assess the possible impact of such mechanical abnormalities on the tissue and cellular responses.

Gemella morbillorum mitral valve endocarditis in a patient with a history of mitral valve annuloplasty

A woman with a history of congenital heart disease status post multiple valve operations including mitral valve repair presented with 2 months of low back pain and general malaise. Blood cultures returned positive for Gram-positive cocci. While transthoracic echocardiography did not identify vegetations, transoesophageal echocardiography visualised vegetations on the patient's mitral valve, which had previously undergone repair with annuloplasty. The patient was found to have infectious endocarditis (IE), caused by Gemella morbillorum The patient was treated with over 6 weeks of intravenous antibiotics. Cases of Gemella-associated IE are rare and largely relegated to case reports. This report aims to contribute to the literature regarding this subject, and to further characterise the presentation and treatment of Gemella-associated IE. Additionally, this report emphasises the importance of maintaining a high suspicion of IE in a patient with non-specific malaise in the setting of prior cardiac valve operation.

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.

Computational Assessment of Valvular Dysfunction in Discrete Subaortic Stenosis: A Parametric Study

PURPOSE

Discrete subaortic stenosis (DSS) is a left-ventricular outflow tract (LVOT) obstruction caused by a membranous lesion. DSS is associated with steep aortoseptal angles (AoSAs) and is a risk factor for aortic regurgitation (AR). However, the etiology of AR secondary to DSS remains unknown. This study aimed at quantifying computationally the impact of AoSA steepening and DSS on aortic valve (AV) hemodynamics and AR.

METHODS

An LV geometry reconstructed from cine-MRI data was connected to an AV geometry to generate a unified 2D LV-AV model. Six geometrical variants were considered: unobstructed (CTRL) and DSS-obstructed LVOT (DSS), each reflecting three AoSA variations (110°, 120°, 130°). Fluid-structure interaction simulations were run to compute LVOT flow, AV leaflet dynamics, and regurgitant fraction (RF).

RESULTS

AoSA steepening and DSS generated vortex dynamics alterations and stenotic flow conditions. While the CTRL-110° model generated the highest degree of leaflet opening asymmetry, DSS preferentially altered superior leaflet kinematics, and caused leaflet-dependent alterations in systolic fluttering. LVOT steepening and DSS subjected the leaflets to increasing WSS overloads (up to 94% increase in temporal shear magnitude), while DSS also increased WSS bidirectionality on the inferior leaflet belly (+ 0.30-point in oscillatory shear index). Although AoSA steepening and DSS increased diastolic transvalvular backflow, regurgitant fractions (RF < 7%) remained below the threshold defining clinical mild AR.

CONCLUSIONS

The mechanical interactions between AV leaflets and LVOT steepening/DSS hemodynamic derangements do not cause AR. However, the leaflet WSS abnormalities predicted in those anatomies provide new support to a mechanobiological etiology of AR secondary to DSS.

Discrete Left Ventricle Outflow Tract Obstruction in Children: Incidence and Predictors of Recurrence. A Multi-Center Study

Objectives

The purpose of this study is to measure the incidence of recurrence of discrete subaortic stenosis (DSS) after primary resection in two major cardiac centers in Saudi Arabia and to identify risk factors associated with recurrence.

Methods

Data on 234 patients who were diagnosed with DSS and underwent surgical resection between 1999 and 2018 were retrospectively reviewed. Patient demographics as well as echocardiographic, surgical, and pathological data were compared between patients with recurrence and non-recurrence.

Results

The overall recurrence incidence after primary resection was 44.87% (N = 105). Most patients were male (59%). The median age at the 1^st operation was 60 months (range 3 months to 133 months). The presence of aortic stenosis at the time of diagnosis was significantly associated with recurrence (p-value = 0.002). The overall median peak gradient in which the primary resection was indicated is 60 mmHg (range 11 to 152 mmHg). The median peak gradient pre-operation and post-operation were significantly higher for the recurrence group (p-value=0.018 and p<0.001, respectively). We used univariate and multivariate analysis and controlled for the follow-up time, but there were no significant independent predictors of recurrence.

Conclusion

The recurrence rate of DSS after the primary resection is relatively high in this study. Further prospective studies are needed to draw a definite conclusion on risk factors for recurrence after primary resection.

Co-Existing Subaortic Stenosis in a Patient With Hypertrophic Obstructive Cardiomyopathy: A Rare and Interesting Finding

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disorder leading to left ventricular outflow tract (LVOT) obstruction. It can present with chest pain, syncope, breathlessness, or it may cause sudden cardiac death in some cases. The echocardiography in most cases while cardiac CT or cardiac MRI in selected cases are the important diagnostic modalities to make the diagnosis of HCM. In this case report, we discuss a case of a young female patient previously diagnosed with HCM and presented with palpitations, chest pain, and shortness of breath. Her echocardiography revealed severe asymmetrically hypertrophied left ventricle (LV) with normal function, the systolic anterior motion of the mitral valve was present and a subvalvular aortic membrane was also seen. The CT was also performed showing severe asymmetrical hypertrophied septum and thickened trileaflet tricommissural aortic valve with no calcification or significant valvular aortic stenosis but there was a subaortic membrane (concentric only sparing anteriorly). The presence of subaortic membrane with HCM is a rare finding and it can be a diagnostic challenge and untreated cases are susceptible to progressive heart failure and worsening of the symptoms by further increasing LVOT obstruction. A thorough investigation and planning before surgical intervention is required to achieve optimal results.

Echocardiographic Diagnosis of a Subaortic Membrane Attached to the Free Edge of the Right Coronary Cusp of the Aortic Valve

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Subaortic membranes may attach to the free edge of the aortic valve cusps.

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Subaortic membranes may occur in isolation without other congenital abnormalities.

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TEE may offer better characterization of subaortic membranes.

Critical subaortic stenosis due to fibromuscular ridge in a 66-year-old woman: 2D-3D echocardiography findings

Subvalvular aortic stenosis (SAS) can be either a fixed stenosis resulting from subaortic anatomical obstacle or a dynamic stenosis because of hypertrophic cardiomyopathy. Here, we report a patient with a rare subaortic circumferential fibromuscular tunnel who became unusually symptomatic in her sixth decade of life. Transthoracic and mostly transesophageal echocardiography with 3D application is the preferred diagnostic modality. Indications for surgery include symptoms and LVOT gradient of 50 mm Hg. Our purpose is an image focus on this infrequent case.

Impact of Aortoseptal Angle Abnormalities and Discrete Subaortic Stenosis on Left-Ventricular Outflow Tract Hemodynamics: Preliminary Computational Assessment

Discrete subaortic stenosis (DSS) is an obstruction of the left ventricular outflow tract (LVOT) due to the formation of a fibromuscular membrane upstream of the aortic valve. DSS is a major risk factor for aortic regurgitation (AR), which often persists after surgical resection of the membrane. While the etiology of DSS and secondary AR is largely unknown, the frequent association between DSS and aortoseptal angle (AoSA) abnormalities has supported the emergence of a mechanobiological pathway by which hemodynamic stress alterations on the septal wall could trigger a biological cascade leading to fibrosis and membrane formation. The resulting LVOT flow disturbances could activate the valve endothelium and contribute to AR. In an effort to assess this hypothetical mechano-etiology, this study aimed at isolating computationally the effects of AoSA abnormalities on septal wall shear stress (WSS), and the impact of DSS on LVOT hemodynamics. Two-dimensional computational fluid dynamics models featuring a normal AoSA (N-LV), a steep AoSA (S-LV), and a steep AoSA with a DSS lesion (DSS-LV) were designed to compute the flow in patient-specific left ventricles (LVs). Boundary conditions consisted of transient velocity profiles at the mitral inlet and LVOT outlet, and patient-specific LV wall motion. The deformation of the DSS lesion was computed using a two-way fluid-structure interaction modeling strategy. Turbulence was accounted for via implementation of the k-ω turbulence model. While the N-LV and S-LV models generated similar LVOT flow characteristics, the DSS-LV model resulted in an asymmetric LVOT jet-like structure, subaortic stenotic conditions (up to 2.4-fold increase in peak velocity, 45% reduction in effective jet diameter vs. N-LV/S-LV), increased vorticity (2.8-fold increase) and turbulence (5- and 3-order-of-magnitude increase in turbulent kinetic energy and Reynolds shear stress, respectively). The steep AoSA subjected the septal wall to a 23% and 69% overload in temporal shear magnitude and gradient, respectively, without any substantial change in oscillatory shear index. This study reveals the existence of WSS overloads on septal wall regions prone to DSS lesion formation in steep LVOTs, and the development of highly turbulent, stenotic and asymmetric flow in DSS LVOTs, which support a possible mechano etiology for DSS and secondary AR.

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.

Right Mini-Thoracotomy Subaortic Membrane Resection

OBJECTIVE

Subaortic membrane is an anatomical intracardiac anomaly that may cause discrete subaortic stenosis and aortic insufficiency. Patients requiring subaortic membrane resection may benefit from a minimally invasive approach; however, subaortic membranes are typically resected through a median sternotomy. We present our initial clinical experience of adult patients who have undergone a mini-thoracotomy subaortic membrane resection.

METHODS

Eight patients who underwent an elective subaortic membrane resection performed through a mini-thoracotomy were retrospectively reviewed. A 5-cm mini-thoracotomy incision was made in the 2nd intercostal space; a videoscope was inserted through a separate incision within the same interspace. Cardiopulmonary bypass (CPB) was instituted via central arterial and peripheral venous cannulation and an aortotomy was made. The subaortic membrane was resected with shafted instruments. The left ventricular outflow tract was inspected and CPB was weaned. Thirty-day mortality, intensive care and hospital length of stay, ventilation time, operative times, postoperative morbidity, and need for additional procedures were evaluated.

RESULTS

The median CPB and cross-clamp times were 60 and 42 minutes, respectively. The median time to extubation was 3.6 hours. The median intensive care unit and hospital stay were 22 hours and 3 days, respectively. The postoperative left ventricular outflow tract mean gradients decreased significantly (26.5 vs. 9.4 mm Hg, P = 0.001). There were no conversions to sternotomy, perioperative strokes, or 30-day mortality.

CONCLUSIONS

Subaortic membranes can be resected through a mini-thoracotomy approach with excellent clinical results.

Routine Septal Myectomy During Subaortic Stenosis Membrane Resection: Effect on Recurrence Rates

Recurrence of subaortic stenosis (SubAS) is up to ~ 19% following resection. Historically, treatment has consisted of membrane resection alone. This study investigated the effect of routine septal myectomy in addition to membrane resection. A single-center retrospective review was performed in all patients < 18 years of age undergoing membrane resection with septal myectomy for SubAS from 2003 to 2013. Demographic, perioperative, and follow-up data were collected. Freedom from reoperation and risk factors for reoperation were determined. 107 patients (median age 4.8 years) were included. There was one in-hospital death, five patients (5%) requiring pacemaker, and no iatrogenic ventricular septal defects. Follow-up was 80% complete and median follow-up was 4.9 years (range 0.5-12 years). Fourteen (16%) subjects required reoperation. Freedom from reoperation was 98% at 1 year, 86% at 5 years, and 69% at 10 years (Fig. 1). There was no difference in decrease of peak gradient between subjects who did and did not require reoperation (- 47 vs. - 40 mmHg; p = 0.59). In univariate analysis, chromosomal anomaly (hazard ratio [HR] 5.0, p = 0.02), smaller body surface area (HR 0.1, p = 0.03), and younger age at surgery (HR 0.7, p = 0.01) were significantly associated with reoperation. The routine use of myectomy with membrane excision did not result in a lower rate of reoperation or higher rates of complications compared to historical controls. Younger age, smaller size, and chromosomal anomaly were associated with increased risk for reoperation. Patients with these risk factors may benefit from more intensive long-term follow-up.

Discrete Subaortic Stenosis: Perspective Roadmap to a Complex Disease

Discrete subaortic stenosis (DSS) is a congenital heart disease that results in the formation of a fibro-membranous tissue, causing an increased pressure gradient in the left ventricular outflow tract (LVOT). While surgical resection of the membrane has shown some success in eliminating the obstruction, it poses significant risks associated with anesthesia, sternotomy, and heart bypass, and it remains associated with a high rate of recurrence. Although a genetic etiology had been initially proposed, the association between DSS and left ventricle (LV) geometrical abnormalities has provided more support to a hemodynamic etiology by which congenital or post-surgical LVOT geometric derangements could generate abnormal shear forces on the septal wall, triggering in turn a fibrotic response. Validating this hypothetical etiology and understanding the mechanobiological processes by which altered shear forces induce fibrosis in the LVOT are major knowledge gaps. This perspective paper describes the current state of knowledge of DSS, articulates the research needs to yield mechanistic insights into a significant pathologic process that is poorly understood, and proposes several strategies aimed at elucidating the potential mechanobiological synergies responsible for DSS pathogenesis. The proposed roadmap has the potential to improve DSS management by identifying early targets for prevention of the fibrotic lesion, and may also prove beneficial in other fibrotic cardiovascular diseases associated with altered flow.

Imaging adult patients with discrete subvalvar aortic stenosis

PURPOSE OF REVIEW

Distinction between discrete subvalvar aortic stenosis and other causes of left ventricular outflow obstruction has important implications for predicting natural history and guiding the timing and type of intervention. Imaging, primarily transthoracic echocardiography (TTE), plays a pivotal role in the diagnosis and management of adults with subvalvar aortic stenosis.

RECENT FINDINGS

Most systematic research on imaging of subvalvar aortic stenosis has focused on echocardiography. TTE, especially two-dimensional imaging with color and spectral Doppler, remains the main modality for delineation of the anatomic and hemodynamic features of subvalvar stenosis, associated anomalies and involvement of accessory mitral valve attachments to the subaortic septum or abnormally placed papillary muscles. Transesophageal echocardiography may provide more detailed definition of left ventricular outflow tract anatomy, including the presence and extension of the obstructive subaortic fibroelastic tissue onto the aortic or mitral valve, especially in patients with poor transthoracic windows. The clinical role for advanced imaging technologies, including three-dimensional echocardiography, cardiac magnetic resonance and computed tomography, is evolving but, largely because of the adequacy of established imaging with TTE, remains relatively limited.

SUMMARY

In the absence of other congenital heart defects or alternative indications (e.g. coronary angiography), TTE is usually adequate for the assessment of discrete subvalvar aortic stenosis in the adult. In specific clinical situations, supplemental imaging modalities can play an integral role in clinical decision making.

Subaortic Stenosis: What Lies Beneath

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DSS is generally an acquired and progressive condition.

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Subaortic stenosis often takes the form of a discrete crescentic fibromuscular ridge in the LVOT.

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DSS should be considered when an elevated aortic Doppler gradient is seen in the presence of normal aortic leaflet mobility.

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Surgery is considered when the peak instantaneous gradient is >50 to 60 mm Hg.

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DSS has a high rate of recurrence following surgical intervention.

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.

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.

Subaortic membrane mimicking hypertrophic cardiomyopathy

A 34-year-old man was referred for progressive angina and exertional dyspnoea refractory to medical therapy, with a presumptive diagnosis of hypertrophic cardiomyopathy (HCM). Transthoracic echocardiography (TTE) revealed asymmetric septal hypertrophy without systolic anterior motion of the mitral valve leaflet and with no dynamic left ventricular outflow tract (LVOT) obstruction. However, the LVOT velocity was elevated at rest as well as with provocation, without the characteristic late peaking obstruction seen in HCM. Focused TTE to evaluate for suspected fixed obstruction demonstrated a subaortic membrane 2.2 cm below the aortic valve. Coronary CT angiography confirmed the presence of the subaortic membrane and was negative for concomitant coronary artery disease. Surgical resection of the subaortic membrane and septal myectomy resulted in significant symptomatic relief and lower LVOT velocities on postoperative TTE. This case reminds the clinician to carefully evaluate for alternative causes of LVOT obstruction, especially subaortic membrane, as a cause of symptoms mimicking HCM.

Long-term outcomes and risk factors for aortic regurgitation after discrete subvalvular aortic stenosis resection in children

OBJECTIVES

To characterise long-term outcomes after discrete subaortic stenosis (DSS) resection and to identify risk factors for reoperation and aortic regurgitation (AR) requiring repair or replacement.

METHODS

All patients who underwent DSS resection between 1984 and 2009 at our institution with at least 36 months' follow-up were included. Demographic, surgical and echocardiographic data were reviewed. Outcomes were reoperation for recurrent DSS, surgery for AR, death and morbidities, including heart transplant, endocarditis and complete heart block.

RESULTS

Median length of postoperative follow-up was 10.9 years (3-27.2 years). Reoperation occurred in 32 patients (21%) and plateaued 10 years after initial resection. Survival at 10 years and 20 years was 98.6% and 86.3%, respectively. Aortic valve (AoV) repair or replacement for predominant AR occurred in 31 patients (20%) during or after DSS resection. By multivariable analysis, prior aortic stenosis (AS) intervention (HR 22.4, p<0.001) was strongly associated with AoV repair or replacement. Risk factors for reoperation by multivariable analysis included younger age at resection (HR 1.24, p=0.003), preoperative gradient ≥60 mm Hg (HR 2.23, p=0.04), peeling of membrane off AoV or mitral valve (HR 2.52, p=0.01), distance of membrane to AoV <7.0 mm (HR 4.03, p=0.03) and AS (HR 2.58, p=0.01).

CONCLUSIONS

In this cohort, the incidence of reoperations after initial DSS resection plateaued after 10 years. Despite a significant rate of reoperation, overall survival was good. Concomitant congenital AS and its associated interventions significantly increased the risk of AR requiring surgical intervention.

Outcome in Children Operated for Membranous Subaortic Stenosis

Background:

The optimal surgical procedure for treatment of fibromembranous subaortic stenosis has been a subject of debate. We report our experience with patients treated for membranous subaortic stenosis using membrane resection alone and membrane resection plus aggressive septal myectomy.

Methods:

Patients followed in the pediatric cardiology clinic of a university hospital, who had undergone surgery for subaortic stenosis between 2002 and 2013 were reviewed. Recurrence of subaortic membrane, residual left ventricular outflow gradient, and aortic valve function were analyzed.

Results:

Forty-six patients underwent surgery for subaortic membrane. Of these, 19 had membrane resection plus aggressive septal myectomy, while 27 had membrane resection alone. Mean age at surgery for the membrane resection group was 7.7 ± 3.9 years and 10.9 ± 3.6 years for the membrane resection plus aggressive myectomy group. Preoperative subaortic gradient for the membrane resection group was 75.5 ± 26.7 mm Hg and 103.2 ± 39.7 mm Hg for the membrane resection plus aggressive myectomy group. The mean follow-up left ventricular outflow tract gradient was 42.3 ± 31.3 mm Hg in the membrane resection group, while it was 11.6 ± 6.3 mm Hg in the aggressive septal myectomy group. Nine patients from the membrane resection group had significant regrowth of the subaortic membrane during the follow-up period, while none of the aggressive septal myectomy group had detectable membrane on echocardiography. Seven of the nine patients with recurrence of the subaortic membrane underwent subsequent membrane resection plus aggressive septal myectomy. Intraoperative finding in all these redo cases was recurrence (growth) of a subaortic membrane.

Conclusion:

Aggressive septal myectomy offers less chance of recurrence, freedom from reoperation, and an improved aortic valve function. This is especially important in sub-Saharan settings where a chance of getting a second surgery is unpredictable.

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.