Congenital discrete subaortic stenosis in pregnancy: case report and literature review

Today's growing numbers of pregnant patients with congenital heart defects presents challenges for cardiologists treating adult patients. The case is presented of a 19-year-old woman who was admitted with a threatened miscarriage in the third trimester and was diagnosed with an incomplete atrioventricular canal, cleft mitral valve with severe regurgitation, and severe congenital subaortic stenosis caused by a subaortic membrane. She was managed conservatively, delivered via cesarean section, and then underwent surgical repair of all defects with good outcome. Here, a review is provided of the literature on the natural course, complications, and treatment strategies of subaortic stenosis, together with a summary of recommendations for the management of the condition.

Echocardiographic assessment of the aortic valve and left ventricular outflow tract

The previous reviews in this section of our Supplement1,2 have summarized the anatomic components of the ventriculo-arterial junctions, and then assessed the echocardiographic approach to the ventriculo-arterial junction or junctions as seen in the morphologically right ventricle. In this complementary review, we discuss the echocardiographic assessment of the comparable components found in the morphologically left ventricle, specifically the outflow tract and the arterial root. We will address the echocardiographic anatomy of the aortic valvar complex, and we will review the causes of congenital arterial valvar stenosis, using the aortic valve as our example. We will also review the various lesions that, in the outflow of the morphologically left ventricle, can produce subvalvar and supravalvar stenosis. We will then consider the salient features of the left ventricular outflow tract in patients with discordant ventriculo-arterial connections, and double outlet ventricles. To conclude the review, we will briefly address some rarer anomalies that involve the left ventricular outflow tract, showing how the transesophageal echocardiogram is used to assist the surgeon preparing for repair. The essence of the approach will be to consider the malformations as seen at valvar, subvalvar, or supravalvar levels,1 but we should not lose sight of the fact that aortic coarctation or interruption, hypoplasia of the left heart, and malformations of the mitral valve are all part of the spectrum of lesions associated with obstruction to the left ventricular outflow tract. These additional malformations, however, are beyond the scope of this review.

Subaortic membrane in an adult patient with coronary artery disease

A case of subaortic membrane with coronary artery disease in a 48-year-old man is described. He was referred to our hospital for cardiac murmur, which was discovered on routine clinical examination. He had no significant past medical history apart from dizziness while exercising. Subaortic membrane was totally excised; left internal thoracic artery was anastomosed to left anterior descending artery by end-to-side technique. The postoperative 2-year course of the patient was uneventful.

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.

Critical subaortic stenosis in a newborn caused by accessory mitral valve tissue

A 2-week-old newborn girl underwent successful surgery in our clinic for critical subaortic stenosis caused by accessory mitral valve tissue, which, because of excessive growth, protruded into the left ventricular outflow tract. The preoperative pressure gradient below the aortic valve was 80 mm Hg. The operation consisted of resection of the accessory tissue through a combined aortotomy and atriotomy approach without residual pressure gradient and mitral valve incompetence. This approach is recommended to ensure that accessory tissue is removed without damaging the mitral valve.

Influence of open surgical correction on intermediate-term outcome in dogs with subvalvular aortic stenosis: 44 cases (1991-1998)

OBJECTIVE

To compare outcome and intermediate-term survival for dogs undergoing open surgical correction of subvalvular aortic stenosis (SAS) with those for dogs with SAS that did not undergo surgery.

DESIGN

Retrospective study.

ANIMALS

44 dogs with congenital SAS.

PROCEDURE

Maximum instantaneous systolic pressure gradients were determined by use of Doppler echocardiography. Cardiopulmonary bypass and open surgical correction of SAS (membranectomy with or without septal myectomy) was performed in 22 dogs, whereas 22 dogs did not undergo surgical correction. Cumulative survival was compared between surgical and nonsurgical groups, using Kaplan-Meier nonparametric analysis and a Mantel-Cox log-rank test.

RESULTS

Initial systolic pressure gradients were not significantly different for dogs undergoing surgery (128 +/- 55 mm Hg), compared with those that did not undergo surgery (117 +/- 57 mm Hg). Systolic pressure gradients were significantly decreased after surgery in dogs that underwent surgery (54 +/- 27 mm Hg). Cumulative survival was not significantly different between dogs in the surgical and nonsurgical groups. Censoring surgery-related mortality in the analysis still did not reveal a significant difference in cumulative survival between the surgical and nonsurgical groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite reductions in the systolic pressure gradient and possible associated improvement in exercise tolerance, a palliative benefit on survival was not documented in dogs undergoing surgery for SAS.

Use of three-dimensional echocardiography for analysis of outflow obstruction in congenital heart disease

To evaluate the feasibility and accuracy of 3-dimensional (3D) echocardiography in analysis of left and right ventricular outflow tract (LVOT and RVOT) obstruction, 3D echocardiography was performed in 28 patients (age 4 months to 36 years) with outflow tract pathology. Type of lesion and relation to valves were assessed. Length and degree of obstruction were measured. Three-D data sets were adequate for reconstruction in 25 of 28 patients; 47 reconstructions were made. In 13 patients with LVOT obstruction, 3D echocardiography was used to study subvalvular details in 8, valvular in 13, and supravalvular in 1. Four of these 13 patients had complex subaortic obstruction. In 12 patients with RVOT lesions, 3D echocardiography was used to study subvalvular details in 11, valvular in 12, and supravalvular in 2. Three-dimensional reconstructions were suitable for analysis in 100% of subvalvular LVOT, 77% valvular LVOT, 100% supravalvular LVOT, 100% subvalvular RVOT, 50% valvular RVOT, and 50% supravalvular RVOT. Twenty patients underwent operation, and surgical findings served as morphologic control for thirty-four 3D reconstructions (LVOT 17, RVOT 17). Operative findings revealed an accuracy at subvalvular LVOT of 100%, valvular LVOT 90%, supravalvular LVOT 100%, subvalvular RVOT 100%, valvular RVOT 100%, and supravalvular RVOT 100%. Quantitative measurements could adequately be performed. Three-D echocardiography is feasible and accurate for analyzing both outflow tracts of the heart. Particularly, generation of nonconventional horizontal cross sections allows a good definition of extension and severity of lesions.

Aortoventriculoplasty with the pulmonary autograft: the "Ross-Konno" procedure

BACKGROUND

For patients with complex left ventricular outflow tract obstruction, including hypoplastic aortic anulus with or without severe diffuse subaortic stenosis, various aortoventriculoplasty procedures (e.g., Konno procedure and its modifications; extended aortic allograft root replacement) are important management options. In younger patients, however, reoperation for valve replacement is inevitably required, and anticoagulation issues pose additional problems. The pulmonary autograft provides a promising option for aortic valve replacement as part of the aortoventriculoplasty procedure in children. Long-term follow up shows that the pulmonary autograft functions well as the systemic arterial (neoaortic) valve and that valve growth occurs.

METHODS

Between July 1993 and May 1995, 11 patients 4 days to 17 years old (median 12 months) underwent aortoventriculoplasty with pulmonary autograft (Ross-Konno procedure). The diagnoses were aortic stenosis with or without subaortic stenosis (n = 8), Shone complex (n = 2), and interrupted aortic arch with subaortic stenosis (n = 1). On average, 1.9 previous interventions had been performed per patient, including a previous Konno procedure in one patient. The aortic root was replaced with a pulmonary autograft valve. The left ventricular outflow tract was enlarged with a Dacron polyester fabric patch in two patients, with an allograft aortic patch in two patients and a right ventricular infundibular free wall muscular extension harvested in continuity with the autograft in seven patients.

RESULTS

Intraoperative transesophageal echocardiographic assessment revealed mild aortic insufficiency in one patient. One patient had a residual left ventricular outflow tract gradient of 15 mm Hg. Significant complications were cardiac tamponade from bleeding (n = 1) and complete heart block necessitating a permanent pacemaker (n = 1). Follow-up ranged from 2 weeks to 16 months. To date, there have been no late deaths or reoperations. Follow-up echocardiography revealed mild autograft insufficiency in one patient and a 16 mm Hg residual left ventricular outflow tract gradient in one patient.

CONCLUSIONS

Initial experience suggests that aortoventriculoplasty with the pulmonary autograft is an excellent alternative for young patients with complex left ventricular outflow tract obstruction. Because the pulmonary autograft has been shown to grow after implantation, reoperation on the left ventricular outflow tract is likely to be avoided.

[Konno's operation for residual aortic stenosis following Nick's operation--a case report]

A 43-year-old woman successfully underwent the Konno's operation as a reoperative procedure for residual aortic stenosis following the Nicks' operation. The patient had had congenital valvular and subvalvular aortic stenosis and a patent ductus arteriosus previously divided. At age 33, she had undergone the Nicks' operation (posterior ring enlargement) and aortic valve replacement with a 19 mm Bicer valve prosthesis 9 years 6 months prior to the reoperation. The preoperative left ventricular-aortic pressure gradient was 120 mmHg which decreased but remained about 60 mmHg after the Nicks' procedure. The patient again developed heart failure and frequent episodes of atrial fibrillation which required repeated hospital admissions. Approximately 10 years following the original procedure, the Konno's operation (anterior ring enlargement) was performed using a 23 mm St. Judes Medical aortic prosthesis to manage residual aortic stenosis. The postoperative course was uneventful and the left ventricular-aortic pressure gradient reduced to 16 mmHg. We conclude that the Konno's operation can be safely performed for residual aortic stenosis following the Nicks' operation.

The natural clinical history of canine congenital subaortic stenosis

The demographics and natural clinical history of canine congenital subaortic stenosis (SAS) were evaluated by retrospective analysis of 195 confirmed cases (1967 to 1991), 96 of which were untreated and available for follow-up evaluation. Of these, 58 dogs had left ventricular outflow systolic pressure gradients available for assessment of severity. All 195 dogs were used for demographic analysis. Breeds found to be at increased relative risk included the Newfoundland (odds ratio, 88.1; P < .001), Rottweiler (odds ratio, 19.3; P < .001), Boxer (odds ratio, 8.6; P < .001), and Golden Retriever (odds ratio, 5.5; P < .001). Dogs with mild gradients (16 to 35 mm Hg) and those that developed infective endocarditis or left heart failure were diagnosed at older ages than those with moderate (36 to 80 mm Hg) and severe (> 80 mm Hg) gradients. Of 96 untreated dogs, 32 (33.3%) had signs of illness varying from fatigue to syncope; 11 dogs (11.3%) developed infective endocarditis or left heart failure. Exercise intolerance or fatigue was reported in 22 dogs, syncope in 11 dogs, and respiratory signs (cough, dyspnea, tachypnea) in 9 dogs. In addition, 21 dogs (21.9%) died suddenly. Sudden death occurred mainly in the first 3 years of life, primarily but not exclusively, in dogs with severe obstructions (gradient, > 80 mm Hg; odds ratio, 16.0; P < .001). Infective endocarditis (6.3%) and left heart failure (7.3%) tended to occur later in life and in dogs with mild to moderate obstructions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic/mitral obstruction and coarctation of the aorta

The prevalence, anatomy and physiology, clinical manifestations, laboratory findings, and management of patients with aortic/mitral obstruction and coarctation of the aorta are assessed. Subaortic stenosis reviewed includes discreet membranous and tunnel subaortic stenosis as well as hypertrophic obstructive cardiomyopathy. The discussion of valvular aortic stenosis includes both congenital and acquired forms of the disease. Supravalvular aortic stenosis is described along with coarctation of the aorta. Mitral valvular stenosis includes the congenital as well as acquired variety with focus on the congenital lesion. Current opinion regarding the medical, the cardiac catheterization, interventional, and the surgical approaches to therapy is presented.

Balloon dilation of congenital subaortic stenosis in the dog

Balloon dilation during cardiac catheterization was evaluated for the treatment of congenital subaortic stenosis (SAS) in nine dogs. Under general anesthesia, bilateral cardiac catheterization was performed through the right jugular vein and carotid artery. Thermodilution cardiac output, and left ventricular and aortic root pressures and angiograms were obtained before and after balloon dilation. Balloons measuring 18-20 mm in diameter and 30-40 mm in length were positioned across the stenosis and three inflations 4-5 minutes apart were performed. There was no significant change in cardiac output, aortic pressure, or degree of aortic regurgitation after balloon dilation. For the entire group balloon dilation resulted in significant decreases in left ventricular systolic pressure (-61.2 +/- 37.2 mm Hg [mean change +/- SD], range -14 to -123), mean systolic pressure gradient (-39.6 +/- 24.4 mm Hg, range -8.4 to -72.2), and peak systolic pressure gradient (-64.3 +/- 46.5 mm Hg, range -17 to -143). Calculated left ventricular outflow cross-sectional area increased significantly (+.4 +/- .5 cm2, range -.06 to + 1.30). Clinical signs improved in the five symptomatic dogs. Individual hemodynamic responses varied widely, but the magnitude of improvement correlated with the severity of obstruction. Three dogs showed a decrease of 60% or greater (> or = 100 mm Hg), and six dogs showed a decrease of 25-50% (17-71 mm Hg) in peak systolic gradient after balloon dilation. Complications were frequent but most were transient and manageable. These preliminary results suggest that balloon dilation can acutely decrease outflow resistance in dogs with SAS and may be effective therapy for some affected dogs.

Obstruction of the left ventricular outflow tract: anatomical observations and surgical implications

Obstruction within the outflow tract from the left ventricle can take several anatomic forms. To understand better these substrates, we reviewed the anatomy in the normal heart and, with this background, focused on the malformations observed at each level of the outflow tract which produce stenosis. We examined 75 malformed hearts and reviewed the literature pertinent to surgical aspects of obstruction. Close study of the normal aortic valve shows the lack of any discrete fibrous structure which can be described in terms of a ring-like annulus. The semilunar attachment of the leaflets makes a crown-shaped arrangement at the ventriculo-arterial junction rather than a strict ring. In the pathological study, valvar abnormalities were found in 45 cases. The valve had three leaflets in 20 cases, two leaflets in 24 cases and one leaflet in to the other. In two cases, additional obstruction was found at the sinutubular junction. Subvalvar stenosis was found in 30 hearts, the aortic valve being trifoliate in 28 and bifoliate in 2. The main substrate of subvalvar obstruction was posterior malalignament of the outlet septum (40%), followed by muscular septal hypertrophy (23%); obstruction was also an intrinsic feature in association with atrioventricular septal defects (14%). Although rare in our material, it can also be due to a fibrous or fibromuscular shelf. In our review of the literature, we have highlighted the various forms of valvar malformation and commented on the surgical options. Clear analysis of both the level of obstruction, and its precise anatomic substrate are essential for optimal surgical intervention.

Shone's anomaly: report of one case

A two-month-old female infant presented with intractable congestive heart failure and cyanosis, present since the neonatal period. The echocardiogram and angiogram showed a parachute mitral valve, aortic and subaortic stenosis, perimembranous type ventricular septal defect, mild aortic coarctation and patent ductus arteriosus. Unfortunately, the patient expired two days after surgical angioplasty for coarctation of the aorta. The autopsy proved a typical case of Shone's anomaly.

Congenital left ventricular outflow tract obstruction

Congenital obstruction of the left ventricular outflow tract remains a significant problem. Obstruction may involve the subvalvar, valvar or supravalvar portion of the aortic valve complex. Congenital valvar stenosis presenting in the neonatal period represents a spectrum of disorders ranging from the hypoplastic left heart syndrome to almost normal hearts. Preoperative echocardiography may allow the selection of infants who are suitable for biventricular repair, with the therapeutic options including open valvotomy and balloon valvotomy, but the determination of the optimal method of treatment will require long term follow up data. Subvalvar obstruction may be discrete or diffuse, and the extent will determine the appropriate therapy. Discrete membranes may be managed by a simple excision while diffuse involvement of the subvalvar region may require a more extensive reconstructive procedure such as the Konno procedure. Supravalvar aortic stenosis is the least common form of aortic stenosis and may be associated with abnormalities of the pulmonary arteries. Treatment is often palliative rather than corrective with all types of congenital left ventricular outflow tract obstruction, and many patients will require reoperations, especially those with valvar and subvalvar obstruction. The lack of long term follow up data for patients treated in the neonatal period makes the choice of an optimal therapy difficult. New methods of valve replacement such as the pulmonary autograft may improve long term results.

Intraoperative transesophageal echocardiographic demonstration of mitral leaflet tear following resection of a subaortic membrane

A patient developed a tear of the anterior mitral leaflet following surgical resection of a stenotic subaortic membrane. This complication was diagnosed by intraoperative transesophageal echocardiography leading to successful repair of the mitral leaflet tear.

Aortic valve reconstruction in Rubinstein-Taybi-syndrome: the valuable aid of transesophageal echocardiography

A fourteen year old boy with Rubinstein-Taybi-syndrome presented with a severe congenital subvalvular fibrous aortic stenosis with associated aortic regurgitation. Transthoracic echocardiographic imaging and left heart angiography showed a transvalvular peak systolic pressure gradient of 90 mmHg and a regurgitant fraction of 30%. The surgical treatment consisted of resection of the subvalvular fibrous tissue and subsequent aortic valvuloplasty. Intraoperative transesophageal echocardiography revealed a wide systolic opening of the aortic valve and good coaptation of the aortic valve leaflets in diastole. Two-dimensional color-coded and contrast echocardiography were successfully used to confirm a satisfactory reconstruction. Transesophageal echocardiography therefore represents a valuable tool in the assessment of the morphologic and haemodynamic status, especially in rare cases of congenital heart disease in older children.

Malaligned outlet septum with subpulmonary ventricular septal defect and abnormal ventriculoarterial connection: a morphologic spectrum defined echocardiographically

A retrospective analysis of 62 echocardiograms from 22 patients with malaligned outlet septum, subpulmonary ventricular septal defect and abnormal ventriculoarterial (VA) connection was performed and the results were confirmed by intraoperative inspection, cardiac catheterization and angiography, or pathologic specimen analysis in 21 of the 22 patients. The purpose of this study was to determine the relative incidence of the primary morphologic features; the correlation between the presence or absence of mitral valve to pulmonary valve fibrous continuity and the type of VA connection; the types and incidence of additional cardiovascular anomalies; and the correlation between the determination of the VA connection by echocardiography versus that ascertained at intraoperative and autopsy inspection. A spectrum of VA connections was found, ranging from double outlet right ventricle (23%) at one extreme, through an intermediate type (64%) in which the pulmonary artery was overriding the ventricular septum, thereby having no consistent and predominant connection to either ventricle, to a discordant VA connection (13%) at the opposite end of the spectrum. All three types of VA connection occurred whether or not there was mitral valve to pulmonary valve fibrous continuity. Additional cardiovascular anomalies were present in 95% of patients, the most common being aortic arch obstructive lesions in 59%, anomalous attachments of the atrioventricular valve tension apparatus in 55% and subaortic stenosis in 50%. A method of echocardiographic determination of the VA connection that correlated with that determined intraoperatively and from pathologic specimen analysis is described.

[A case of supravalvular aortic stenosis treated by Doty's operation]

A 11-year-old boy with supravalvular aortic stenosis was treated by extended aortoplasty (Doty's operation) with excellent results. The extended aortoplasty provided satisfactory relief of aortic stenosis and improved function of the aortic valve.

Fixed subaortic stenosis with congenital aneurysm of sinus of Valsalva--cross-sectional and Doppler echocardiographic diagnosis of a rare association

A 13-year-old girl was diagnosed by cross-sectional and Doppler echocardiography to have the rare combination of congenital aneurysm of the right sinus of Valsalva rupturing into the right ventricular outflow tract and a discrete subaortic fibrous shelf with severe subvalvar stenosis, moderate aortic regurgitation and left ventricular dysfunction. The findings were confirmed at cardiac catheterisation and surgery.

[Subvalvular aortic stenosis. Apropos of 3 cases]

The three cases reported here illustrate the most frequent varieties of infra-valvular congenital aortic stenosis secondary to a fixed obstacle: such as a thin membrane located a few millimeters under the aortic ring; such as a fibro-muscular membrane at some distance of the ring; such as an infra-aortic fibro-muscular tunnel. The clinical symptoms and evolutive risks are reviewed. Ultrasound cardiography enables to make an accurate diagnosis and evaluate the associated lesions. A surgical indication is made in symptomatic forms with a gradient exceeding 40 mmHg. The advantage of early surgery is to decrease the risk of heart failure. The various surgical techniques are presented.