Discrete Subvalvar Aortic Stenosis Research Articles

Subaortic Stenosis Resection in Children: Emphasis on Recurrence and the Fate of the Aortic Valve.

Recurrence after surgical resection of discrete subvalvar aortic stenosis in children often requires repeat operation. Risk factors for recurrence are poorly understood. We sought to determine potential risk factors for recurrence and postoperative comorbidities in the long term. Retrospective chart review was performed on all pediatric patients who underwent surgical resection of discrete subaortic stenosis at our institution. Demographics, perioperative findings, and clinical data were analyzed for predisposing factors. From 1991 to 2015, a total of 104 patients underwent primary surgical resection of discrete subaortic stenosis. There were no postoperative deaths. Three (2.9%) patients required pacemaker implantation. Nine (8.4%) patients required repeat resection for recurrence of subaortic membrane over a median follow-up of 8.5 years (interquartile range: 5.9-13.5 years). Actuarial freedom from repeat resection was 100%, 94%, and 82% at one, five, and ten years, respectively. Repeat resection occurred more frequently in patients with genetic disease (37.5% vs 10.7%; P = .033) and preoperative mitral regurgitation (MR; 25% vs 1.2%; P < .001). Postoperative aortic insufficiency (AI) that was moderate or worse was associated with older age at the time of first resection (relative risk [RR]: 1.54, P < .05), moderate or severe preoperative AI (RR: 1.84, P = .002), and repeat resection of subaortic stenosis (RR: 1.90, P < .001). The majority of children who undergo surgical resection of subaortic stenosis will not experience recurrence in childhood and those who do require repeat resection may have a higher incidence of genetic disease and preoperative MR. Postoperative AI is associated with repeat resection, older age at the time of surgery, and degree of preoperative AI.

Imaging adult patients with discrete subvalvar aortic stenosis.

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. 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. 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.

Application of Multiple Novel Imaging Modalities for Guidance and Treatment of the Patient with Subaortic Stenosis

Discrete Subvalvar Aortic Stenosis (DSS) is an uncommon acquired cause of left ventricular outflow tract obstruction (LVOT) and often found during Transthoracic Echocardiography (TTE). The membranes are located adjacent to the Aortic Valve (AV) or extended to the anterior leaflet of the mitral valve. The high-velocity systolic jet collides and damages the AV leaflets making the valve more likely to fail and more susceptible to clot and vegetation formation. There is an increased risk of moderate to severe Aortic Insufficiency (AI) when the peak LVOT gradient reaches >50mmHg. The clinical course of subvalvar aortic stenosis is generally progressive with increasing obstruction and progression of AI. Surgical resection of the fibrous ridge with myomectomy is the treatment of choice. The DSS was discovered unexpectedly in this 42 year-old white male with a past medical history of ascending aortic aneurysm, diabetes, hypertension and hyperlipidemia. He was admitted with chest pain, shortness of breath and syncope. TTE showed normal left ventricle with calcified and thickened AV. Peak LVOT gradient was 48mmHg. Due to poor acoustic window, Transesophageal Echocardiogram (TEE) with real time 3-dimensional imaging (RT3D-TEE) was performed. TEE revealed a membranous structure located in the LVOT below a severely calcified AV. Doppler study revealed peak LVOT gradient of 57mmHg with a mean gradient of 38mmHg. Severe AI was also noted. Patient received a #25mm porcine valve with resection of the subaortic membrane and septal myomectomy. Pathology report revealed rubbery, fibromembranous tissue, consistent with DSS. Patient did well after surgery and was discharged home in 4 days. Application of multiple novel imaging modalities, such as TEE and RT-3D-TEE allowed us to better characterize the structure of the DSS and provide guidance for better surgical outcome.

Subvalvular aortic stenosis associated with valvular aortic regurgitation in young child

Discrete subvalvar aortic stenosis is a variable and progressive disease. Recurrent obstruction may reappear despite the adequacy of surgical excision. Aortic regurgitation is associated with numerous eponymous signs, it is also a complication of discrete subvalvar aortic stenosis and its detection often triggers referral for surgery. It has also been suggested that an infant or young child with a well-defined 30 mm Hg or more peak gradient should have removal of the subvalvar obstruction. We describe a case of subvalvular aortic stenosis associated with aortic regurgitation in a 10-year-old Italian boy.

Risk factors for aortic valve dysfunction in children with discrete subvalvar aortic stenosis

Aortic regurgitation (AR) is a known complication of discrete subvalvar aortic stenosis (DSS), and its detection often triggers referral for surgery. However, risk factors for aortic valve dysfunction in children with DSS remain incompletely defined. The primary goal of this study was to determine independent risk factors for moderate or severe AR at mid-term follow-up in patients with DSS. Clinical records and echocardiograms of 220 patients with DSS (109 patients had DSS resection and 111 had no surgery) were analyzed. The primary outcome variable was AR grade (based on the width of the vena contracta) at latest follow-up. Age at diagnosis, gender, and duration of follow-up (median 7.2 years, range 1 to 20.4) did not differ significantly between medical and surgical patients. By multivariate analysis, independent risk factors for moderate to severe AR (n = 30) were older age at diagnosis of DSS (odds ratio [OR] for age ≥17 years 5.13, p = 0.024), previous balloon or surgical aortic valvuloplasty (OR 19.6, p <0.001), and a longer follow-up period (OR for 1-year increase 1.15, p = 0.032). Excluding patients with previous surgical or balloon aortic valvuloplasty, a higher maximal Doppler gradient was an independent risk factor for moderate to severe AR (OR for peak gradient ≥50 mm Hg 10.8, p = 0.001). Independent predictors of low-risk patients (none or trivial AR and peak gradient ≤30 mm Hg) included thin and mobile aortic valve leaflets (OR 7.86, p = 0.006) and an associated ventricular septal defect (OR 2.18, p = 0.019). These clinical and echocardiographic variables can be used to stratify risk of aortic valve dysfunction in patients with DSS and aid in timing of surgical resection.

Decision-making in pediatric cardiology: searching for the evidence

The goal of evidence-based decision-making in pediatric cardiology and cardiac surgery may be difficult if not impossible to attain. This is due to the rarity, complexity and variability in the morphology and physiology of congenital heart disease. Nevertheless, constant attention to the process of searching for the evidence maximizes flexibility in decision-making and limits adherence to unproven management regimens. The long-term acceptance of prolonged bed rest for the treatment of acute rheumatic fever without significant evidence of benefit illustrates this principle. The result was unnecessary hospitalizations and restrictions on children as well as high medical cost. Much of the ‘conventional wisdom’ for medical and surgical treatment of congenital heart disease in the 1960s–1980s is no longer relevant. Without constant attention to evolving evidence gleaned from basic and clinical research, many of today's management pathways will not be appropriately altered and new pathways will not emerge. Analyses of treatment principles related to ventricular septal defect and discrete subvalvar aortic stenosis are presented, and questions are raised concerning other pediatric cardiac conditions where evidence-based outcome data are limited. The challenge to pediatric cardiologists and cardiac surgeons will always be to ‘search for the evidence’ in order to constantly reassess and adjust management pathways for children with heart disease.

Exercise testing in children before and after surgical treatment of aortic stenosis.

Twenty-three children with valvar or discrete subvalvar aortic stenosis underwent a controlled, progressive bicycle exercise test within 6 months before and 3-30 months after surgery for left ventricular outflow tract obstruction. The patients were divided into three groups according to the preoperative resting gradient of left ventricular to aortic peak systolic pressure: 30-69 mm Hg (group A), 70-99 mm Hg (group B), and greater than or equal to 100 mm Hg (group C). Preoperatively, 19 of 23 patients (83%) developed significant ST depression (greater than or equal to 1.0 mm) during exercise, whereas only seven (30%) had abnormal ST depression at rest. Postoperatively, mean exercise-induced ST depression regressed to less than 1 mm in all three groups. In the total population the frequency of ST depression greater than 1 mm was significantly reduced after surgical treatment and mean total work and peak exercise systolic blood pressure were significantly increased within 12 months after surgery. Total work increased significantly in group B within 12 months and in group C within 13-24 months after surgery, but remained unchanged on group A. Peak exercise heart rates were similar before and after surgery in each group. Peak exercise systolic pressures increased after surgery in all three groups, but the mean differences were statistically significant only in group C patients tested 13-24 months after surgery. The results of this study show that exercise testing is useful for quantifying the severity of aortic stenosis and documenting the clinical improvement (or lack thereof) after surgical treatment, and that properly supervised exercise testing can be performed at minimal risk to children with significant aortic stenosis.

Subendocardial ischaemia in patients with discrete subvalvar aortic stenosis.

The evidence for subendocardial ischaemia was studied in 12 patients with discrete subvalvar aortic stenosis. Symptomatology, electrocardiographic criteria, and pressure difference across the left ventricular outflow tract were compared with the subendocardial flow index (diastolic pressure time index systolic pressure time index). All symptomatic patients had a large pressure difference and abnormal index, but 4 asymptomatic patients had pressure differences greater than 60 mmHg and a low index. One of these 4 patients had a normal resting electrocardiogram. In patients with borderline accepted indications for surgery, calculation of the subendocardial flow index may be an additional useful variable in the timing of surgery.

SPECTRUM OF EXERCISE RESPONSES IN CHILDREN WITH AORTIC STENOSIS

Significant abnormalities in cardiovascular dynamics may occur during exercise (Ex) in patients (P) with aortic stenosis (AS). This study was designed to record systolic pressure (ESP), electrocardiogram (ECG) and working capacity (WC) during upright bicycle Ex in 50 preoperative P (ages 6 to 23 years) with valvar or discrete subvalvar AS. Ninety-six normal children (ages 5 to 21 years) were the controls (C). Resting aortic gradients (AG) in the P ranged up to 234 mmHg at cardiac catheterization. Mean (±standard error) Ex data were subdivided by BSA and/or sex. In M and F < 1.2M2, ESP were 115±4 in P and 133±4 in N, p < .01. WC's were 77±11 in P and 88±8 in N, p > .1. ESP was below resting value in 2 and increased up to 10 mmHg in 8 P with AG ≥ 60 mm Hg. A positive Ex ECG occurred in 15/17 (88%) P with AG ≥ 60, 16/30 (53%) with AG of 10 to 59, 0/3 with AG < 10 and 7/96 (7%) N. ST depression (ST ↓) occurred in 16/30 P with normal resting ECG and 15/20 with left ventricular hypertrophy. We concluded that increased frequency of ST ↓, decreased ESP and WC are typical changes which may reflect severity or progression of AS in children.

Discrete subvalvar aortic stenosis in childhood

Discrete subvalvar aortic stenosis in childhood

Congenital discrete subvalvar aortic stenosis. Surgical experience and long-term follow-up in 20 paediatric patients.

Congenital discrete subvalvar aortic stenosis. Surgical experience and long-term follow-up in 20 paediatric patients.