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

Perioperative and Anesthetic Considerations in Pediatric Valvar and Subvalvar Aortic Stenosis

Aortic stenosis (AS) is a common form of left ventricular outflow tract obstruction (LVOTO) in children with congenital heart disease. This review specifically considers the perioperative features of valvar (VAS) and subvalvar AS (subAS) in the pediatric patient. Although VAS and subAS share some clinical features and diagnostic approaches, they are distinct clinical entities with separate therapeutic options, which range from transcatheter intervention to surgical repair. We detail the pathophysiology of AS and highlight the range of treatment strategies with a focus on anesthetic considerations for the care of these patients before, during, and after intervention.

Surgical treatment of recurrent subvalvular discrete membrane and left ventricular outflow tract stenosis in an adult patient with a history of congenital cardiac surgery

Left ventricular outflow stenosis can develop at the supravalvular, valvular, and subvalvular levels. Resection of strictures at the diffuse subvalvular level is very difficult. In such pathologies, Konno-Rastan procedure provides very successful solutions as an anterior aortoventriculoplasty method. In this article, we performed anterior aortaventriculoplasty surgical treatment for tunnel type left ventricular outflow tract stenosis, recurrent subvalvular discrete membrane, and aortic regurgitation in an adult patient with a history of partial atrioventricular septal defect repair and subvalvular discrete membrane resection operation in early childhood. The Konno-Rastan procedure, which we applied to the redo case, which is rarely used in adult patients and rarely seen in the literature, is shared.

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 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.

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.

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.

Congenital coronary artery anomaly simulating a ventricular septal defect

Anomalous origin of the circumflex artery of the right sinus of Valsalva is a rare finding which may be present with other cardiac malformations. A 19-year-old man presented with syncope. A transthoracic echocardiogram revealed discrete subaortic stenosis with a small defect just below the aortic valve, suggesting a ventricular septal defect. Transesophageal echocardiography showed anomalous origin of the circumflex artery from the right sinus of Valsalva. This was confirmed by coronary angiography. The patient underwent successful web resection without concomitant coronary surgery. Failure to demonstrate a coronary artery anomaly can be misleading for surgeons and perilous for patients.

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.

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.

Subaortic membrane late after surgical correction of tetralogy of Fallot

We herein report a rare case of subaortic stenosis in association with a previous tetralogy of Fallot (TOF) surgical repair, which was not taken into account as a differential diagnosis. Echocardiography plays a pivotal role in identification of this rare combination. Therefore, echocardiography should be performed periodically during follow-up of patients with surgically corrected TOF. Given the clinical complications that can result from subaortic stenosis (i.e., aortic regurgitation and infective endocarditis), early and aggressive management of this rare combination should be performed.

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.

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.

Discrete subaortic membranes in adults--a clinicopathological analysis

INTRODUCTION

A discrete subaortic membrane (DSM) is one of the causes of subaortic stenosis in children. The incidence, characteristics, and the therapeutic options for such membranes in adults have not been well documented. This report documents the clinical and pathological features of DSM in adults.

METHODS

DSMs, surgically excised over a 10-year period in a large adult tertiary care center, were reviewed with regard to the age and gender of the patients, clinical findings, and the morphological features.

RESULTS

Among the 19 adults, there were six males and 13 females, with age ranging from 26 to 75 years. The patients most often presented with dyspnea, fatigability, and palpitation for 3 months to 2 years. Four patients (21%) had other congenital heart disease in association with the DSM; in the rest, the membranes were isolated occurrences (79%). A cardiac murmur or the presence of membranes had been noted in childhood in four patients. Tissue growths over the ventricular surface of the anterior mitral leaflet were seen in 18 cases. Irrespective of the gross appearance, the stenosing lesions exhibited five tissue layers, beginning from the luminal aspect, endothelium, acid mucopolysaccharide-rich subendothelial layer, collagen-rich fibrous layer, fibroelastotic layer, and a smooth muscle layer. Twelve patients (63%) had aortic regurgitation, which necessitated repair or replacement in seven. Septal myectomy resulted in conduction abnormalities in nine.

CONCLUSIONS

The study describes the occurrence of DSM in adults. It is important to remember that it can occur following a repair of underlying congenital heart disease.

Subaortic stenosis missed by invasive hemodynamic assessment

We present a case of 61-year-old man that was evaluated for possible aortic stenosis but did not show a left ventricular outflow gradient on invasive assessment in the catheterization laboratory. Transthoracic echocardiography showed subaortic stenosis secondary to a discrete membranous structure in the left ventricular outflow tract. This is the first case in the literature of a patient with discrete subaortic stenosis missed by invasive hemodynamic assessment.

Risk factors for reoperation after repair of discrete subaortic stenosis in children

OBJECTIVES

This study aimed to identify independent predictors of reoperation after successful resection of discrete subaortic stenosis (DSS).

BACKGROUND

Recurrence of DSS has been reported to range from 0% to 55% of patients. Factors associated with recurrence have not been adequately defined.

METHODS

Patients were included if they had a diagnosis of DSS, normal segmental cardiac anatomy, previous resection of DSS, and at least 36 months' follow-up. Demographic, surgical, and echocardiographic data were analyzed. Primary outcome was repeat resection of DSS in patients after successful primary resection.

RESULTS

Of 111 subjects who had successful surgical resection of DSS, 16 patients (14%) required reoperation. Median follow-up time was 8.2 years. Form of DSS and gender did not differ significantly between those with reoperation and those without. In multivariate analysis, independent predictors of reoperation that would be available before first surgery were <6 mm distance between the aortic valve (AoV) and the obstruction (hazard ratio [HR] 5.1; p = 0.013) and peak gradient by Doppler > or =60 mm Hg (HR 4.2; p = 0.016). If intraoperative variables are also considered, peeling of the membrane from the AoV or mitral valve at first surgery, <6 mm distance between the DSS and AoV, and peak gradient by Doppler > or =60 mm Hg were independent predictors of reoperation.

CONCLUSIONS

Proximity of the obstructive lesion to the AoV and severe obstruction determined by preoperative echocardiography, as well as involvement of valve leaflets requiring surgical peeling, predict recurrent DSS requiring reoperation.

Discrete membranous subaortic stenosis complicated by infective endocarditis: a case report

Discrete membraneous subaortic stenosis is an uncommon cause of left ventricular outflow tract obstruction. Although its relationship to infective endocarditis is well defined, the expected site of vegetation is over the aortic valve. We report on a 46-year-old man who had a discrete membranous subaortic stenosis, complicated with infective endocarditis, in which the vegetation was over the subaortic membrane and the aortic valve was spared. To our knowledge, this is the first reported case of that entity.

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.