Subaortic fibrous ridge and ventricular septal defect: role of septal malalignment

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

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

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

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

Long-Term Outcome of Patients with Perimembranous Ventricular Septal Defect: Results from the Belgian Registry on Adult Congenital Heart Disease

OBJECTIVES

Studies evaluating the long-term outcome of adults with ventricular septal defect (VSD) are important to inform patients about prognosis. This study investigated the long-term outcome of patients with perimembranous VSD (pmVSD) followed in the Belgian Registry on Adult Congenital Heart Disease.

METHODS

All pmVSD patients in the registry were analyzed.

RESULTS

Two hundred and sixty-six patients were studied. Fifteen patients had Eisenmenger syndrome. One hundred and seventy-three had isolated pmVSD and 78 had pmVSD with concomitant lesions. Of the patients with isolated pmVSD, 52% were male, median age was 29 years (IQR 24-35 years) and median follow-up duration was 18 years (IQR 10-25 years). Fifty-three (31%) patients underwent VSD closure and 10 (19%) had a residual shunt. Most (93%) patients were in NYHA class I. No patients died. Two (4%) patients developed atrial arrhythmia and 2 (4%) required pacemaker implantation. Seven (14%) developed left ventricular outflow tract obstruction (LVOTO). In the unrepaired pmVSD group, 4 developed endocarditis. In the entire group, moderate or severe aortic regurgitation (AR) occurred in 9 (5%) patients.

CONCLUSIONS

Long-term survival in patients with isolated pmVSD was not uneventful. Moderate or severe AR might develop and endocarditis occurred in patients without VSD repair. Complications after VSD closure included atrial arrhythmia, pacemaker implantation and LVOTO.

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.

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.

Minimally invasive perventricular device closure of ventricular septal defect in infants under transthoracic echocardiograhic guidance: feasibility and comparison with transesophageal echocardiography

BACKGROUND

A hybrid approach to minimally invasive perventricular closure of VSD in infants is safe and effective, and has been performed under guidance of transesophageal echocardiography (TEE). We applied transthoracic echocardiographic (TTE) guidance to this hybrid approach, and compare results guided by TTE with those by TEE.

METHODS

From January 2011 to January 2012, 71 infants with VSD were enrolled to undergo a minimally invasive device closure. After evaluation of VSD by TTE, either TEE or TTE was used to guide the minimally invasive device closure. 30 patients had TEE guidance, and 41 patients had TTE. All patients were followed for 3 months after the operation.

RESULTS

The TEE group had a success rate of 93.3% (28/30) for device implantation, compared with 92.7% (38/41) in the TTE group. Two patients in the TEE group turned to surgical closure, one for involvement of the inlet area of VSD demonstrated by TEE, another for moderate aortic regurgitation after device implantation. Two patients in the TTE group also transferred to surgical closure, one for residual shunt, another for failure of the floppy wire across the defect. In addition, one patient in the TTE group experienced dropout of the occluder one day postoperatively. At 3-month follow-up, one patient had mild aortic regurgitation in the TEE group and in two patients in the TTE group. There were no episodes of cardiac block, thromboembolism, or device displacement in either group.

CONCLUSIONS

TTE-guided VSD closure is feasible in infants, with results similar to those of TEE guidance, although caution is advisable.

Spontaneously healed membranous type ventricular septal defect with malaligned interventricular septal wall and double-chambered right ventricle in a 56-year-old patient

A 56-year-old male presented with resting dyspnea and chest discomfort for several years. During transthoracic and transesophageal echocardiography, a spontaneously healed membranous type ventricular septal defect (VSD) with malaligned interventricular septal wall, aneurysmal changes, a subaortic ridge and a double-chambered right ventricle (DCRV) was observed. When combined with DCRV, VSD with malalignment between the outlet and trabecular septa was associated with tetralogy of Fallot. The subaortic ridge was due to turbulent flow caused by the malalignment-type VSD. The VSD with malaligned interventricular septal wall can be developed after aneurismal changes of a perimembranous VSD. We report here in the unusual case of a 56-year-old patient who had a pathology complex comprising DCRV, subaortic ridge, spontaneously healed membranous type VSD with malaligned interventricular septal wall, and survived with surgical treatment.

Aneurysm of the ventricular membranous septum: serial echocardiographic studies

OBJECTIVES

The aim of this article is to examine the frequency, timing of formation of aneurysm of the ventricular membranous septum (AVMS), and prognosis in patients with a perimembranous ventricular septal defect (VSD).

PATIENTS

One hundred forty-eight patients were diagnosed with a perimembranous VSD within 90 days after birth. They were classified into three groups: Group I, spontaneous closure; Group II, open; Group III, surgical closure. They were also divided into two further groups: 75 patients with congestive heart failure (CHF) and 73 patients without that.

METHODS

An AVMS was observed by two-dimensional echocardiography, and spontaneous closure of the VSD was confirmed by color Doppler.

RESULTS

An AVMS was formed in 69 (47%) of 148 patients: 50% in Group I, 66% in Group II, 15% in Group III. The timing of AVMS formation was at a median age of 6 months. In 14% of patients, AVMS was formed within 3 months of age. The frequency of AVMS at the time of the initial echocardiogram was low in patients with CHF (odds ratio, 3.23; 95% confidence interval, 1.19-8.79 p = 0.017).

CONCLUSIONS

We believe that AVMS formation is related to avoidance of surgical closure during early infancy in patients with a perimembranous VSD, because the frequency of AVMS during early infancy is low in patients with CHF.

Rheology of discrete subaortic stenosis

The discrete form of subaortic stenosis is thought to be an acquired lesion, the aetiology of which may be a combination of factors which include an underlying genetic predisposition, turbulence in the left ventricular outflow tract, and various geometric and anatomical variations of the left ventricular outflow tract. A review of hypotheses relating to its aetiology is provided

Echocardiographic, morphologic, and geometric variations of the left ventricular outflow tract: possible role in the pathogenesis of discrete subaortic stenosis

Although the clinical features and natural course of discrete subaortic stenosis (DSS) are well defined, the etiology remains speculative. The purpose of this study was to identify the echocardiographic, morphologic, and geometric variations of the left ventricular outflow tract associated with DSS in children and to determine whether these variations have a role in the pathogenesis of DSS. The aortoseptal angle (ASA), mitral-aortic valve separation (MAS), and the size of the aortic annulus were determined in two groups of children. Group 1 comprised 11 patients with isolated DSS, who were compared with an age- and body surface area- (BSA) matched healthy children (Group 1A, n: 20). Group 2 comprised 10 patients with DSS and ventricular septal defect (VSD). Group 2 was compared with an age- and BSA-matched patients with isolated perimembranous VSD (Group 2A, n: 22). Measurements were carried out from previously recorded echocardiographic studies. The ASA was steeper (119.3 +/- 6.1 degrees vs 137.5 +/- 5.6 degrees , p < 0.001), and the MAS was wider (6.1 +/- 1.6 vs 3.2 +/- 0.7 mm, p < 0.001) in patients with isolated DSS than in healthy control subjects. Similar differences were found between patients in Group 2 and Group 2A; the ASA was steeper (122.2 +/- 6.5 degrees vs 141.3 +/- 5.0 degrees, p < 0.001), and the MAS was wider (5.8 +/- 1.5 vs 3.8 +/- 1.1 mm, p < 0.001). The size of the aortic annulus was not different among the four study groups. Although the MAS was significantly wider in patients with DSS, there was significant overlap in MAS between patients and controls. However, if an ASA < or = 130 degrees was chosen as a predictive variable, it was found to be a highly sensitive, specific, and positive predictive marker for the development of DSS. This study demonstrates that DSS is associated with a steeper ASA, and a wider MAS, in patients with or without associated VSD. These morphologic abnormalities, especially a steeper ASA, may be risk factors for the development of DSS.

Mobilization of the left and right fibrous trigones for relief of severe left ventricular outflow obstruction

BACKGROUND

There is still no agreement about the optimal method of surgical relief of fixed subaortic stenosis, particularly the severe forms.

OBJECTIVES

The purpose of this study was to describe a new technique for the relief of subaortic stenosis based on analysis of the functional anatomy of the left ventricular outflow tract and pathophysiologic features of subaortic stenosis.

METHODS AND PATIENTS

We propose that one of the basic abnormalities in subaortic stenosis is interference with the hinge mechanism provided by the 2 fibrous trigones with progressive deposition of fibrous tissue in these angles. The technique described in this paper consists of excision of all components of the fibrous "ring," with mobilization of the left and right fibrous trigones. This results in the restoration of the normal dynamic behavior of the left ventricular outflow tract with maximal widening of the outflow tract as the result of backward displacement of the subaortic curtain and anterior leaflet of the mitral valve. This technique has been used in 57 consecutive patients who ranged in age between 5 months and 56 years (mean, 15.5 +/- 10.6 years). Gradients across the left ventricular outflow tract were between 45 and 200 mm Hg (mean, 86.7 mm Hg). Additional lesions were present in 10 patients, and 7 patients had had 8 previous operations on the left ventricular outflow tract. At operation, in addition to resection of subaortic stenosis, 3 patients had aortic valvotomy, 2 patients had homograft replacement of the aortic valve, 7 patients had patch closure of a ventricular septal defect, and 1 patient had open mitral valvotomy.

RESULTS

There were 2 early deaths and 1 late sudden death during the follow-up period that ranged from 1 month to 25 years (mean, 15. 2 years). One patient experienced the development of endocarditis on the aortic valve 7 years after operation, which was successfully treated by homograft replacement. Postoperative gradients across the left ventricular outflow tract varied from no gradient to 30 mm Hg (mean, 8 mm Hg). There were no instances of recurrence of a gradient across the left ventricular outflow tract.

CONCLUSION

It is concluded that mobilization of the left and right fibrous trigones results in durable relief of subaortic stenosis.

Development and validation of an echocardiographic model for predicting progression of discrete subaortic stenosis in children

The clinical course of discrete subaortic stenosis (DSS) varies considerably between patients. This study was performed to identify echocardiographic characteristics of DSS that distinguish progressive from nonprogressive disease. The study included 100 patients from 2 institutions and was performed in 2 stages. In phase I, a prediction model was developed based on multivariate analysis of morphometric and Doppler variables obtained from the initial echocardiogram in 52 children with DSS from Texas Children's Hospital. In phase II, the performance characteristics of the prediction model were tested in 48 patients with DSS followed at Children's Hospital in Boston. Patients were divided into 3 outcome groups: nonprogressive, progressive, and intermediate progression. In phase I, multivariate analysis identified 3 independent predictors of progressive disease: indexed aortic valve to subaortic membrane distance, anterior mitral leaflet involvement, and initial Doppler gradient. The logistic regression equation--Probability = [1 + e-(-322+0.334X1+4.06X2-0.708X3)](-1), where X = initial gradient in mm Hg; X2 = absence (0) or presence (1) of mitral leaflet involvement; and X3 = indexed distance between aortic valve and subaortic membrane in mm/body surface area0.5 were used to predict progression. When the prediction model was applied to phase II study patients, none of the patients with nonprogressive DSS had a prediction value > 0.29 and none of the patients with progressive DSS had a prediction value < 0.58. Thus, a prediction value > 0.55 yielded a 100% sensitivity and 100% specificity for distinguishing progressive from nonprogressive DSS. Patients with intermediate progression were indistinguishable from progressive DSS but were clearly separable from nonprogressing patients. We conclude that progressive subaortic obstruction in children with DSS can be predicted from morphologic, morphometric, and Doppler echocardiographic analysis of left ventricular outflow.

Potential role of mechanical stress in the etiology of pediatric heart disease: septal shear stress in subaortic stenosis

OBJECTIVES

The objective of this study was to show elevations in septal shear stress in response to morphologic abnormalities that have been associated with discrete subaortic stenosis (SAS) in children. Combined with the published data, this critical connection supports a four-stage etiology of SAS that is advanced in this report.

BACKGROUND

Subaortic stenosis constitutes up to 20% of left ventricular outflow obstruction in children and frequently requires surgical removal, and the lesions may reappear unpredictably after the operation. The etiology of SAS is unknown. This study proposes a four-stage etiology for SAS that I) combines morphologic abnormalities, II) elevation of septal shear stress, III) genetic predisposition and IV) cellular proliferation in response to shear stress.

METHODS

Morphologic structures of a left ventricular outflow tract were modeled based on measurements in patients with and without SAS. Septal shear stress was studied in response to changes in aortoseptal angle (AoSA) (120 degrees to 150 degrees), outflow tract convergence angle (45 degrees, 22.5 degrees and 0 degree), presence/location of a ventricular septal defect (VSD) (3-mm VSD; 2 and 6 mm from annulus) and shunt velocity (3 and 5 m/s).

RESULTS

Variations in AoSA produced marked elevations in septal shear stress (from 103 dynes/cm2 for 150 degrees angle to 150 dynes/cm2 for 120 degrees angle for baseline conditions). This effect was not dependent on the convergence angle in the outflow tract (150 to 132 dynes/cm2 over full range of angles including extreme case of 0 degree). A VSD enhanced this effect (150 to 220 dynes/cm2 at steep angle of 120 degrees and 3 m/s shunt velocity), consistent with the high incidence of VSDs in patients with SAS. The position of the VSD was also important, with a reduction of the distance between the VSD and the aortic annulus causing further increases in septal shear stress (220 and 266 dynes/cm2 for distances of 6 and 2 mm from the annulus, respectively).

CONCLUSIONS

Small changes in AoSA produce important changes in septal shear stress. The levels of stress increase are consistent with cellular flow studies showing stimulation of growth factors and cellular proliferation. Steepened AoSA may be a risk factor for the development of SAS. Evidence exists for all four stages of the proposed etiology of SAS.

Abnormalities of the left ventricular outflow tract associated with discrete subaortic stenosis in children: an echocardiographic study

OBJECTIVES

The purpose of this study was to examine the echocardiographic abnormalities of the left ventricular outflow tract associated with subaortic stenosis in children.

BACKGROUND

Considerable evidence suggests that subaortic stenosis is an acquired and progressive lesion, but the etiology remains unknown. We have proposed a four-stage etiologic process for the development of subaortic stenosis. This report addresses the first stage by defining the morphologic abnormalities of the left ventricular outflow tract present in patients who develop subaortic stenosis.

METHODS

Two study groups were evaluated-33 patients with isolated subaortic stenosis and 12 patients with perimembranous ventricular septal defect and subaortic stenosis-and were compared with a size- and lesion-matched control group. Subjects ranged in age from 0.05 to 23 years, and body surface area ranged from 0.17 to 2.3 m2. Two independent observers measured aortoseptal angle, aortic annulus diameter and mitral-aortic separation from previously recorded echocardiographic studies.

RESULTS

The aortoseptal angle was steeper in patients with isolated subaortic stenosis than in control subjects (p < 0.001). This pattern was also true for patients with ventricular septal defect and subaortic stenosis compared with control subjects (p < 0.001). Neither age nor body surface area was correlated with aortoseptal angle. A trend toward smaller aortic annulus diameter indexed to patient size was seen between patients and control subjects but failed to achieve statistical significance (p = 0.08). There was an excellent interrater correlation in aortoseptal angle and aortic annulus measurement. The mitral-aortic separation measurement was unreliable. Our results, specifically relating steep aortoseptal angle to subaortic stenosis, confirm the results of other investigators.

CONCLUSIONS

This study demonstrates that subaortic stenosis is associated with a steepened aortoseptal angle, as defined by two-dimensional echocardiography, and this association holds in patients with and without a ventricular septal defect. A steepened aortoseptal angle may be a risk factor for the development of subaortic stenosis.

Posterior deviation of left ventricular outflow tract septal components without ventricular septal defect

OBJECTIVE

To describe 11 patients with narrowing of the left ventricular outflow tract caused by angular posterior deviation of both the outlet septum and the upper part of trabecular septum, which was diagnosed by cross sectional echocardiography in all and confirmed by angiocardiography in seven.

RESULTS

Four patients had a subaortic systolic pressure gradient ranging from 23 to 70 mm Hg by Doppler echocardiography; cardiac catheterisation showed a significant (60 and 104 mm Hg) systolic pressure gradient in two. In four cases aortic regurgitation and two tricuspid pouches were shown by Doppler echocardiography, angiocardiography, or both. Four cases had a ridge at the angulation point on echocardiographic examination. Three patients were operated on for systolic pressure gradients of the left ventricular outflow tract and one for severe aortic regurgitation. There was proliferation of collagen-rich fibrous tissue in the subendocardial region on histopathological examination of the myectomy material. A ventricular septal defect had been diagnosed previously by contrast echocardiography in one patient; thus ventricular septal defects may close spontaneously over a period of time including fetal life. A subaortic ridge was detected in one patient at follow up.

CONCLUSIONS

Deviation of the outlet and trabecular septa should be considered as a cause of ventricular outflow tract obstruction even when no ventricular septal defect is present.

Malalignment-type ventricular septal defect in double-chambered right ventricle

Double-chambered right ventricle (DCRV) is commonly associated with ventricular septal defect (VSD). In this study, an assessment was made of the relevance of a malalignment-type VSD to hemodynamic and morphologic features in DCRV. During an 8.5-year period, 53 patients with DCRV were enrolled after study with echocardiography, catheterization, and angiography. Patients were divided into 2 groups: group I included 40 patients, aged 3.7 +/- 3.2 years, with a malalignment-type VSD; group II consisted of 13 patients, aged 8.6 +/- 2.7 years, without a malalignment-type VSD. History of congestive heart failure in infancy was present in 21 group I and 2 group II patients (53% vs 15%, respectively, p <0.05). The mean pulmonary-to-systemic flow ratio was significantly higher in group I than in group II (1.89 +/- 0.74 vs 1.14 +/- 0.21, respectively, p <0.05). The mean pressure gradient across the right ventricular outflow tract was lower in group I than in group II (41 +/- 16 vs, 73 +/- 33 mm Hg, respectively, p <0.05). Among 42 patients who had a series of echocardiograms recorded, progression of pressure gradient was evident in 35: 28 in group I and 7 in group II. A subaortic ridge was present exclusively in 29 group I patients (73%). Prolapse of the aortic valve was present in 26 (49%): 20 group I (50%) and 6 group II (46%) patients. Aneurysm formation of the septal defect was found in 17 (43%) and 7 (54%) group I and II patients, respectively. It can be concluded that a history of congestive heart failure was more common in DCRV patients with a malalignment-type VSD. Malalignment-type VSD is significantly associated with a larger pulmonary-to-systemic flow ratio and subaortic ridge.

Implication of anterior septal malalignment in isolated ventricular septal defect

OBJECTIVE

The aim was to define the long term prognosis of isolated ventricular septal defect (VSD) with anteriorly malaligned outlet septum.

DESIGN

Cohort study.

SETTING

University hospital, tertiary medical care centre.

PATIENTS

Between July 1986 and June 1993, 63 patients were studied with an isolated VSD and anteriorly malaligned outlet septum (59 perimembranous; 4 muscular outlet).

MAIN OUTCOME MEASURES

The diagnosis of septal malalignment, aneurysmal transformation, right ventricular obstruction, subaortic ridge, and aortic valve prolapse was based on echocardiographic criteria, then confirmed by angiography in 33 patients and by surgery in 28. An actuarial curve for each event was obtained by Kaplan-Meier non-parametric analysis and the significance was examined by log-rank test.

RESULTS

Aneurysmal transformation decreased the size of the VSD in 52% of the patients, but was also associated with the appearance of subaortic ridge (p < 0.05). Progressive obstruction in the right ventricle was observed in 51%, more often in those without aneurysmal transformation (p < 0.05). Aortic valve prolapse was quite common whether or not aneurysmal transformation occurred (33% and 23%, respectively). This was attributed to the location of the VSD and the anterior malalignment of the outlet septum. Surgery was performed in 28 patients at a median age of 50 months because of significant left to right shunt (n = 5), or the development of obstruction in right ventricle (n = 9), aortic valve prolapse (n = 3), or combinations (n = 11). The presence of subaortic ridge per se was not considered to be a surgical indication.

CONCLUSIONS

Anteriorly malaligned VSDs have variable presentation. Careful echocardiographic evaluation is needed to identify various combinations of progressive right ventricular obstruction, aneurysmal transformation, subaortic ridge, or aortic valve prolapse. In extreme cases a patient may have a pathology complex comprising right ventricular outflow obstruction, subaortic ridge, aortic valve prolapse, and anteriorly malaligned VSD.

Morphology of left ventricular outflow tract structures in patients with subaortic stenosis and a ventricular septal defect

OBJECTIVE

To compare the incidence and prognosis of subaortic stenosis associated with a ventricular septal defect and to define the morphological basis of subaortic stenosis.

DESIGN

Presentation and follow up data on 202 patients with subaortic stenosis seen at the Royal Liverpool Children's Hospital between 1 January 1960 and 31 December 1991 were reviewed. Survivors were traced to assess their current clinical state. Necropsy specimens of 291 patients with lesions associated with subaortic stenosis were also examined.

RESULTS

In the clinical study; 65 (32.1%) of the 202 patients with subaortic stenosis had a ventricular septal defect (excluding an atrioventricular septal defect). 32 of these patients had a short segment (fibromuscular) subaortic stenosis. 33 had subaortic stenosis produced by deviation of muscular components of the outflow tracts. In 17 patients (51.5%) this was caused by posterior deviation or extension of structures into the left ventricular outflow tract, resulting in obstruction above the ventricular septal defect. In the other 16 patients (48.5%) there was over-riding of the aorta with concordant ventriculoarterial connections, (without compromise to right ventricular outflow) producing subaortic stenosis below the ventricular septal defect. Additional fibrous obstruction occurred in 39% of the patients with deviated structures. The age at presentation was lower (P < 0.01) in patients with deviated structures (median (range) 0.4 (0 to 9.2) months) than in those with short segment obstruction (median (range) 4.2 (0 to 84.9) months). The incidence of aortic arch obstruction was higher (P < 0.002) in patients with deviated structures than in those with short segment obstruction (38%). In the morphological study 35 pathological specimens showed obstructive muscular structures in the left ventricular outflow tract either above or below the ventricular septal defect. 16 had either posterior deviation of the outlet septum or extension of the right ventriculoinfundibular fold, or both of these together into the left ventricle. 19 had anterior deviation of the outlet septum into the right ventricle with overriding of the aorta (without compromise to right ventricular outflow). The earliest age at which additional fibrous obstruction was seen was 9 months. The aortic valve circumference was small in 18% of specimens.

FOLLOW UP

The median (range) duration of follow up in survivors from the clinical study was 6.6 (1 to 25.7) years. 16 patients with deviated musculature (49%) and 16 with short segment fibromuscular stenosis (50%) underwent operation for subaortic stenosis. Patients with deviated structures were younger at operation than those with short segment stenosis (P < 0.005). Patients with posterior deviation or extension of structures into the left ventricular outflow tract underwent operation for subaortic stenosis more frequently (P < 0.05) than those with anterior deviation of the outlet septum and aortic override. The ventricular septal defect required surgical closure more frequently (P < 0.005) in patients with deviation (93.9%) than in those with short segment obstruction (21.9%). There was no significant difference in the mortality between patients with deviation (27%) and those with short segment obstruction (12%).

CONCLUSIONS

32% of patients in the clinical study with subaortic stenosis had a ventricular septal defect. Only 51% of these had obstructive and deviated muscular structures in the left ventricular outflow tract. These patients had a significantly higher incidence of aortic arch obstruction and required surgery for subaortic stenosis at a younger age than those with short segment obstruction. The ventricular septal defect also required surgical closure more frequently in those patients with deviation. The morphological study defined the two sites of obstruction. The presence or absence and type of deviation should be clearly defined in all patients with a ventricular septal defect,

Echocardiographic morphometry and geometry of the left ventricular outflow tract in fixed subaortic stenosis

OBJECTIVES

This study was designed to identify, by echocardiography, morphometric abnormalities of the left ventricular outflow tract in children with fixed subaortic stenosis and to determine whether these abnormalities precede the development of subaortic obstruction.

BACKGROUND

Fixed subaortic stenosis typically develops and progresses after the 1st year of life and is therefore often regarded as an acquired lesion. Although it has been speculated that there may be an underlying anatomic substrate, there are no data to support this hypothesis.

METHODS

The size of the aortic annulus, mitral-aortic valve separation, aorto-left ventricular septal angle and degree of aortic override were determined in two groups of children. Group 1 comprised 35 patients with isolated subaortic stenosis noted on initial echocardiogram who were compared with an age- and weight-matched normal control group (Group 1A). Group 2 comprised 23 patients with ventricular septal defect or coarctation of the aorta, or both, who had no subaortic stenosis on initial echocardiogram but who developed it subsequently. This group was compared with an age-, weight- and lesion-matched control group (Group 2A).

RESULTS

Compared with control subjects, patients with isolated subaortic stenosis had a significantly wider mitral-aortic separation ([mean +/- SD] 5.1 +/- 1.3 vs. 3.4 +/- 0.9 mm, p < 0.001), a steeper aortoseptal angle (131 +/- 6 degrees vs. 144 +/- 5 degrees, p < 0.001) and an exaggerated aortic override (p < 0.05). Similar differences were found on initial echocardiogram in Group 2 patients before development of subaortic stenosis: wider mitral-aortic separation (4.2 +/- 1.2 vs. 2.5 +/- 0.7 mm, p < 0.001), a steeper aortoseptal angle (132 +/- 7 degrees vs. 145 +/- 7 degrees, p < 0.001) and an exaggerated aortic override (p < 0.05).

CONCLUSIONS

A left ventricular outflow tract malformation characterized by a wider mitral-aortic separation, an exaggerated aortic override and a steeper aortoseptal angle are present in children with ventricular septal defect or coarctation of the aorta, or both, who subsequently develop subaortic stenosis. These morphometric features can be used to identify by echocardiography patients who are at risk for developing fixed subaortic stenosis.

Implication of aneurysmal transformation in isolated perimembranous ventricular septal defect

Defects on the membranous ventricular septum (perimembranous ventricular septal defect [VSD]) may spontaneously close or diminish in size by "aneurysmal transformation" (i.e., adherence of the tricuspid valve or adjacent tissue onto the VSD). It was recently shown that the appearance of aneurysmal transformation may be associated with subaortic ridges, as well as left ventricular (LV)-to-right atrial (RA) shunts. In all, 877 consecutive patients with isolated perimembranous VSD were retrospectively studied. Results of actuarial analysis showed that patients with a perimembranous VSD had a 98% probability of aneurysmal transformation by the age of 240 months. Of these patients, the expected probabilities of developing LV-RA shunt, spontaneous closure and subaortic ridge were 45, 35 and 6%, respectively. Patients with LV-RA shunts had higher probabilities of developing infective endocarditis (p = 0.002) and persistent left-to-right shunts (p < 0.001). The presence of a subaortic ridge may be accompanied by LV outflow tract obstruction (10 of 25 patients), infundibular pulmonary stenosis (n = 3), or aortic valve deformity or aortic regurgitation (n = 5), and none of those with a subaortic ridge closed spontaneously. It was confirmed that a substantial proportion of aneurysmal transformation of isolated perimembranous VSD is associated with LV-RA shunts and subaortic ridges.

Rheologic genesis of discrete subvalvular aortic stenosis: a Doppler echocardiographic study

To determine whether morphologic structures or abnormal flow patterns predispose to pathologic proliferation of subvalvular tissue, 26 patients (mean age 19.8 +/- 10.3 years) were studied greater than or equal to 6 months after operation for isolated discrete subvalvular aortic stenosis. The aortic root diameter and the mitral-aortic separation were measured with sector echocardiography. Flow patterns in the left ventricular outflow tract of these patients and control subjects were evaluated with a color flow mapping system optimized for the detection of turbulence. All control subjects had laminar flow throughout systole in the left ventricular outflow tract. By contrast, turbulence originating well below the site where the shelf had previously been resected was observed in 20 (77%) of the 26 patients. In 16 of these 20 patients turbulence was caused by a ridge, which in 13 patients could be identified as the offshoot of a ventricular band. In four patients the turbulence was caused by malalignment of the muscular and membranous septum, resulting in protrusion of the muscular septum into the outflow tract. Except for the latter four patients, the aortic root diameter was 84 +/- 10% of values predicted by body surface area, with values in six patients falling below the third percentile (p less than 0.01). The mitral-aortic separation was 9.7 +/- 3.5 mm, values in 21 patients falling above the 97th percentile (p less than 0.001). These data support the theory that discrete subvalvular aortic stenosis may be caused by a chronic flow disturbance, preferably in a small and long outflow tract. Left ventricular bands, if reaching the outflow tract, may be a factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Severe subaortic stenosis in interrupted aortic arch in infancy and childhood

Thirteen out of a total 50 infants with interrupted aortic arch (IAA) seen between 1979-1988 had or developed severe subaortic stenosis (SAS). One had type A interruption and 12 type B. All had a large ventricular septal defect (VSD). The infundibular septum was displaced posteriorly in eight infants, severely narrowing the left ventricular outflow tract (LVOT). Three had fibromuscular narrowing of the LVOT, one each a subaortic muscle bar and membrane. The aortic root and subaortic area were small and measured between 3-8 mm. An anomalous right subclavian artery was noted in eight of the 12 type B IAA, the anomalous vessel arising from the descending aorta in seven. Thirteen infants with IAA and SAS were submitted to surgery, 12 having their subaortic area resected with three perioperative deaths early in the series and three late deaths where active treatment was ceased, including one infant with renal dysplasia who had had a successful establishment of arch continuity and pulmonary artery banding. Of the seven survivors, six have residual Doppler gradients of between 20-50 mmHg, two requiring a second resection and one a third resection. Alternate management programs are suggested based on anatomical evaluation and echocardiography. Any newborn presenting with IAA requires careful evaluation of the subaortic area, best seen on cross-sectional echocardiography. The improved surgical survival in infants following complete repair of IAA has led this important associated anomaly of subaortic stenosis to assume greater importance as a cause of mortality and long-term morbidity.

An echocardiographic study of the association of ventricular septal defect and right ventricular muscle bundles with a fixed subaortic abnormality

Since 1983, 36 patients with the combination of right ventricular muscle bundles and a perimembranous ventricular septal defect have been studied in our institution to address the incidence of on associated subaortic abnormality. Of that total 32 (88%) had echocardiographic evidence of such an abnormality (29 had a typical subarotic ridge protruding from the crest of the interventricular septum and the remaining 3 had an echodense area in the same location). Surgical confirmation of the presence or absence of a subaortic abnormality was available in 26. There was correlation between the surgical and echocardiographic findings in all patients. A resting Doppler gradient of greater than or equal to 10 mm Hg was present in only 10. During the study period, 6 patients had Doppler evidence of progression of their gradient. The incidence of subaortic abnormalities in right ventricular muscle bundles and ventricular septal defects appears to be far greater than previously suspected. The exact significance of this finding in the absence of a pressure gradient is still unclear.