Ventricular septal defects: a surgical viewpoint

Borders as opposed to so-called geography: which should be used to classify isolated ventricular septal defects?

OBJECTIVES

Ventricular septal defects can be classified according to their borders or according to the fashion in which they open to the right ventricle, so-called geography. As yet, there is no consensus as to how they should be classified. In an attempt to achieve agreement, the International Society for Nomenclature of Congenital and Paediatric Heart Disease, in 2018, proposed a system incorporating both approaches. We have assessed the subjectivity of their suggested terms hoping to determine their suitability in the desired universal system for classification.

METHODS

We examined 212 specimens held in the archive of Birmingham Women's and Children's Hospital. Each defect was described by 3 independent examiners on the basis of borders and their relationship to the landmarks of the right ventricle. The interobserver agreement was then calculated using Fleiss' method.

RESULTS

Calculations to assess interobserver agreement showed that the examiners were more likely to agree on the borders of the defects than their so-called geography (κ = 0.804 vs κ = 0.518). The landmarks of the right ventricle proved to be highly variable such that the application of 'geographic' terms to hearts with perimembranous defects proved particularly challenging.

CONCLUSIONS

Interobserver agreement is lower when using terms based on 'geography' as opposed to borders. Whilst providing important morphological detail, the terms based on right ventricular landmarks are highly subjective. They should not be prioritized in a universal system of classification. Instead, the defects can be classified simply by using 'perimembranous', 'muscular', or 'doubly committed and juxta-arterial' as first-order terms.

A new anatomic approach of the ventricular septal defect in the interruption of the aortic arch

The aim of this study was to analyse the anatomy of the ventricular septal defect (VSD) in heart specimens with interruption of the aortic arch (IAA) in order to explore the hypothesis of different embryologic mechanisms for the different anatomic types of IAA. We examined 42 human heart specimens, 25 with IAA as the main disease with concordant atrioventricular and ventriculo-arterial connections and two distinct great arteries, and 17 hearts with IAA associated with other malformations [six common arterial trunk (CAT), five double-outlet right ventricle (DORV), three transposition of the great arteries (TGA), three atrioventricular septal defect (AVSD)]. The interruption was classified according to Celoria and Patton. We focused on the anatomy of the VSD viewed from the right ventricular side. There were 15 IAA type A, 27 type B, no type C. The VSD in IAA type B was always an outlet VSD, located between the two limbs of the septal band, with posterior malalignment of the outlet septum in hearts with concordant ventriculo-arterial connections, without any fibrous tricuspid-aortic continuity. In addition, the aortic arch was always completely absent. Conversely, the VSD in IAA type A could be of any type (outlet in six, muscular in four, central perimembranous in two, inlet in three) and the aortic arch was either atretic or absent. In addition, IAA type B, when found in the setting of another anomaly, was always associated with neural crest-related anomalies (CAT and DORV), whereas IAA type A was found in association with anomalies not related to the neural crest (TGA and AVSD). These results reinforce the hypothesis that different pathogenic mechanisms are responsible for the two types of IAA, and the inclusion of IAA type B in the group of neural crest defects. Conversely, IAA type A could be due to overlapping mechanisms: flow-related defect (coarctation-like) and neural crest contribution.

Ventricular Septal Defect Closure Devices, Techniques, and Outcomes

Transcatheter closure of ventricular septal defects (VSDs) was first documented in 1988. The early studies of VSD closure were successful but there were high complication rates, particularly early and late-onset complete heart block. However, the development and use of new vascular occlusion devices in an off-label fashion has improved the range of patients who can be treated and reduced the complication rates. In particular, the rate of complete heart block documented in contemporary studies of VSD closure has fallen to levels at or below those documented in the surgical VSD closure literature.

Anatomy of the ventricular septal defect in congenital heart defects: a random association?

Background

A ventricular septal defect (VSD) is an integral part of most congenital heart defects (CHD). To determine the prevalence of VSD in various types of CHD and the distribution of their anatomic types.

Methods

We reviewed 1178 heart specimens with CHD from the anatomic collection of the French Reference Centre for Complex Congenital Heart Defects. During the morphologic study a special attention was paid to the localisation of the VSD viewed from the right ventricular side. The VSDs were classified as muscular, central perimembranous, outlet located between the two limbs of the septal band, and inlet. The specimens were classified according to the 9 categories and 23 subcategories of the anatomic and clinical classification of CHD1 (ACC-CHD).

Results

Ventricular septum was almost always intact in anomalies of pulmonary veins (4/73, 5%), Ebstein anomaly (3/21, 14%), and double-inlet right ventricle (DIRV, 1/10, 10%). There was always a VSD in tetralogy of Fallot and variants (TOF, 123 cases) and common arterial trunk (CAT, 55 cases), always of the outlet type. There was almost always a VSD in double inlet left ventricle (33/34, 97%, always muscular), congenitally corrected transposition of great arteries (ccTGA, 23/24, 96%), interrupted aortic arch (IAA, 25/27, 93%), and double outlet right ventricle (DORV, 92/106, 87%). A VSD was found in 68% of aortic coarctation (CoA, 43/63), 62% of heterotaxy syndromes (21/34), 54% of transposition of the great arteries (TGA, 104/194). The VSD was located between the two limbs of the septal band in 100% of TOF and CAT, 80% of IAA, 77% of DORV, 82% of DD. The VSD was of the inlet type in 17% of cc TGA and in 71% of heterotaxy syndromes. In TGA, the VSD was outlet in 40%, central perimembranous in 25%, muscular in 25%, inlet in 10%. In CoA, the VSD was outlet in 44%, central perimembranous in 35%, muscular in 21%. In the 10% hearts with isolated VSD, the distribution was outlet in 44%, central perimembranous in 36%, muscular in 18%, and inlet in 2%.

Conclusion

The anatomic distribution of VSD is similar in isolated VSD, CoA and TGA, while the VSD is predominantly outlet in outflow tract defects except TGA. This reinforces the allegedly different mechanisms in TGA and cardiac neural crest defects. This anatomic approach could provide new insights in the grouping and aetiology of CHD.

Holes and channels between the ventricles revisited

BACKGROUND

Although holes, or channels, between the ventricles are the commonest congenital cardiac malformations, there is still no consensus as to how they can best be described and categorised. So as to assess whether it is possible to produce a potentially universally acceptable system, we have analysed the hearts categorised as having ventricular septal defects in a large archive held at Birmingham Children's Hospital. Materials and methods We analysed all the hearts categorised as having isolated ventricular septal defects, or those associated with aortic coarctation or interruption in the setting of concordant ventriculo-arterial connections, in the archive of autopsied hearts held at Birmingham Children's Hospital, United Kingdom.

RESULTS

We found 147 hearts within the archive fulfilling our criterions for inclusion. All could be classified within one of three groups depending on their borders as seen from the right ventricle. To provide full description, however, it was also necessary to take account of the way the defects opened to the right ventricle, and the presence or absence of alignment between the septal components.

CONCLUSIONS

By combining information on the phenotypic specificity defined on the basis of their borders, the direction of opening into the right ventricle, and the presence or absence of septal malalignment, it proved possible to categorise all hearts examined within the archive of Birmingham Children's Hospital. Our findings have necessitated creation of new numbers within the European Paediatric Cardiac Code.

The problems that exist when considering the anatomic variability between the channels that permit interventricular shunting

Although steps are being taken to produce a universally acceptable coding system for categorisation of the congenitally malformed hearts, obstacles remain in the search for consensus. One of the groups of lesions continuing to produce the greatest problems is those that permit interventricular shunting. The difficulties relate partly to the words used to describe the group itself, as those using Germanic languages describe the holes as ventricular septal defects, whereas those using Romance languages consider them to represent interventricular communications. The two terms, however, are not necessarily synonymous. Further disagreements relate to whether the lesions placed within the group should be sub-categorised on the basis of their geographical location within the ventricular mass, as opposed to the anatomic nature of their borders. In reality, attention to both the features is necessary if we are to recognise the full extent of phenotypic variability. In this review, we first review the evolution and theories of analysis naming the channels that permit interventricular shunting. We then demonstrate that embryologic techniques provide evidence that the changing morphology of the developing murine heart parallels the anatomy of the different lesions encountered in the congenitally malformed human heart. We suggest that, with attention paid to the temporal development of the normal murine heart, combined with a strict definition of the plane of separation between the right and left ventricular cavities, it will be feasible to produce a categorisation that is acceptable to all.

Color Doppler echocardiographic study on the incidence and natural history of early-infancy muscular ventricular septal defect

BACKGROUND

Most small muscular ventricular septal defect (M-VSD) types have been diagnosed using color Doppler echocardiography. The purpose of this study was to understand the incidence of small M-VSD in the neonatal period and analyze the natural history of these M-VSDs.

MATERIALS AND METHODS

All individuals in our study were neonates delivered at term who had a normal healthy appearance. Each accepted neonate had an examination with complete color Doppler echocardiography once before discharge. If the examination was confirmed for M-VSD, the study participants were then classified according to defect type. Further examination was arranged with color Doppler echocardiography at 1 month, 2 months, 4 months, 6 months, 9 months, and 12 months of age or until there was complete spontaneous closure.

RESULTS

Among 2891 neonates, we found that 72 (24.9/1000) were diagnosed with M-VSD. Among this group, 38 were male and 34 were female. Only six infants were lost to follow-up. Fifty-four of the 66 infants (81.8%) had M-VSD closed spontaneously at 12 months' follow-up. Significantly, 33 of 37 infants (89.2%) with mid-muscular type, the most common type of M-VSD, closed within the 1(st) year of life compared with apical type (17/24:70.8%). Four of the five infants (80%) had anterior type M-VSD closed. Infants with posterior type M-VSD were not seen during this study period.

CONCLUSION

Although the incidence of M-VSD was common in the neonatal period, there was also a high rate of spontaneous closure. Therefore, comparison of M-VSD appearance with the incidence of congenital heart disease in neonates had a decisive influence on analysis.

Ventricular septal defect

Ventricular septal defects account for up to 40% of all congenital cardiac malformations. The diagnosis encompasses a broad range of anomalies, including isolated defects and those associated with other congenital cardiac malformations. Presentation, symptoms, natural history, and management of ventricular septal defects depend on size and anatomical associations of the anomaly, patient's age, and local diagnostic and interventional expertise. In this Seminar, we describe the anatomical range of ventricular septal defects and discuss present management of these malformations. Genetic determinants, diagnostic techniques, physiological considerations, and management challenges are examined in detail. Unfortunately, in many circumstances, evidence on which to guide optimum management is scarce. We present some longer term considerations of ventricular septal defects in adolescents and adults, with particular emphasis on patients with raised pulmonary vascular resistance and Eisenmenger's syndrome.

Aortic valvar involvement in patients undergoing closure of ventricular septal defect via the pulmonary trunk

BACKGROUND

To determine how often the aortic valve is involved in doubly-committed ventricular septal defect in a surgical series, and when to intervene to minimize aortic valvar impediments.

METHODS

The defect was surgically closed in 415 patients via the pulmonary trunk, age at operation ranging from 2 months to 76 years old. In infants, pulmonary hypertension or pulmonary high flow was the exclusive indication. Any progressive deformity of the aortic leaflet or aortic regurgitation was an alternative principal indication in older children or adolescents. No additional manoeuvres were employed for the aortic root unless aortic regurgitation is more than slight. Otherwise, the aortic valve was repaired or replaced. When the sinus of Valsalva was significantly deformed or ruptured, the structure was surgically restored.

RESULTS

Significant aortic regurgitation or the ruptured sinus of Valsalva was increasingly found beyond the paediatric age. Bacterial endocarditis was seen in 8% of adults or adolescents. Silent herniation of the aortic leaflet was not uncommon after 4 years old, seen in more than 40% of patients. Need of aortic valvar repair was rare before 2 years old, and in approximately 10% between 2 and 15 years old. Freedom from reoperation was 89% at 10 years and 78% at 25 years after aortic valvar repair, and 91% and 84%, respectively, after replacement, versus 100% and 99.4%, respectively, after no additional valvar procedure.

CONCLUSION

Aortic valvar involvement was rare, and ventricular septal defect was closed without impediments, before 2 years old. Surgery should be arranged before any additional aortic valvar manoeuvre is needed.

Feasibility and Accuracy of Real-time 3-Dimensional Echocardiographic Assessment of Ventricular Septal Defects

The aim of this study was to evaluate feasibility, accuracy, and clinical applicability of real-time (RT) transthoracic 3-dimensional (3D) echocardiography (3DE) in the determination of the position, size, and shape of a ventricular septal defect (VSD). In all, 34 patients (age: 2 months-46 years), who were scheduled for surgical closure of a VSD, were enrolled in the study. VSD localization, shape, and dimensions were assessed and compared with measurements performed by the surgeon. Acquisition of RT-3DE datasets was feasible in 30 of 34 (88%) patients. Duration of 3D data acquisition was 6 +/- 2 minutes. Reconstruction time was 23 +/- 16 minutes. Localization and number of VSD were determined correctly by RT-3DE in all patients. There was a good correlation for VSD measurements between RT-3DE and operation (r = 0.95). RT-3DE allows accurate determination of VSD size, shape, and location. The short acquisition time and acceptable reconstruction time make this technique clinically applicable.

Closure of muscular ventricular septal defects guided by en face reconstruction and pictorial representation

BACKGROUND

A surface reconstruction of the location and dimensions of muscular ventricular septal defects (VSDs) on right ventricular (RV) septal surface could serve as a better guide to surgical closure amid different classifications and confusing terminologies.

METHODS

We reconstructed muscular VSD requiring surgery on an en-face view of the RV septal surface from echocardiographic orthogonal views in 34 consecutive patients. The location, dimensions of the defects, and relation to various RV septal landmarks are illustrated as a diagram. Recommendations are presented regarding surgical approach to the defects, along with predictions on the possibility of residual defects and heart block.

RESULTS

Surgical findings were as predicted by the diagram in the 27 patients who underwent VSD closure. Seven infants (2.5 to 4.9 kg) underwent pulmonary artery (PA) banding based on predictions of heart block or major residual defects. Two patients with predicted risk of heart block underwent VSD closure with heart block ensuing in one of them. Based on the diagram limited ventriculotomy (n = 2) or detachment of tricuspid leaflets (n = 6) aided access to the VSD. Among patients undergoing VSD closure only 1 patient had a major residual defect that required PA banding. There were clinically insignificant residual defects in 8 patients. Four patients (12%) were anticipated preoperatively because of surgical inaccessibility and intentionally left alone.

CONCLUSIONS

En-face reconstruction of single or multiple muscular VSDs is feasible from orthogonal echocardiographic views. It helps plan the surgical approach and predict the likelihood of heart block and residual defects after surgery.

Outcomes of intraoperative device closure of muscular ventricular septal defects

BACKGROUND

The surgical management of muscular ventricular septal defects (mVSD) in the small infant is a challenge particularly when multiple and associated with complex cardiac lesions. Devices for percutaneous implantation have the advantage of ease of placement and for the double umbrella designs a wide area of coverage. We reviewed our experience and clinical outcomes of intraoperative mVSD device closure for such defects in small infants.

METHODS

Since October 1989, intraoperative VSD device closure was a component of the surgical strategy in 14 consecutive patient implants (median age, 5.5 months; range, 3 to 11 kg), whose defects were thought difficult to approach using conventional techniques. Nine patients had associated complex cardiac lesions, 10 multiple mVSDs, and 4 patients had a previous pulmonary artery banding.

RESULTS

There were 2 early deaths, 1 in a severely ill child who preoperatively had pulmonary hypertension and left ventricular failure and another in a patient with a hypoplastic left heart. Mean pulmonary to systemic flow ratio before device insertion was 3.5:1. Complete closure was achieved in 5 patients and clinically insignificant residual shunts persisted in 7. In 2 infants with significant residual lesions concomitant pulmonary artery banding was required. Postoperative mean pulmonary to systemic flow ratio was 1.7:1. In follow-up of the 12 surviving infants (mean, 41 months), 8 had complete closure and 3 persistent residual shunts. One patient with no residual shunting required heart transplantation for progressive ventricular failure 9 years after operation. All devices were well positioned on postoperative echocardiograms. There was 1 late death due to aspiration in a patient with a tiny residual shunt.

CONCLUSIONS

Infants requiring operative intervention with mVSDs are difficult to manage and have an increased mortality and morbidity. Intraoperative VSD device placement for closure of mVSDs is feasible, can avoid ventriculotomy, division of intracardiac muscle bands, and is ideally suited for the neonate or infant.

Congenital Heart Surgery Nomenclature and Database Project: ventricular septal defect

The extant nomenclature for ventricular septal defect (VSD) is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. Four basic VSD types are described: Subarterial, Perimembranous, Inlet, and Muscular. A comprehensive database set is presented which is based on a hierarchical scheme. Data are entered at various levels of complexity and detail which can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analysis. A minimum database set is also presented which will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

"Swiss cheese" septal defects: surgical closure using a single patch with intermediate fixings

BACKGROUND

Residual ventricular septal defects and ventricular and septal dysfunctions are surgical drawbacks of "Swiss cheese" defects. We developed a technique that uses a single patch with intermediate fixings to cover the right side of the septum without producing a septal bulging, through a right atriotomy.

METHODS

Since April 1993, 5 children with "Swiss cheese" defects have been operated on using this procedure (mean age, 17 +/- 12 months). Three patients had associated lesions including tetralogy of Fallot, Taussig Bing heart, and mitral stenosis.

RESULTS

There have been no early or late deaths. The mean follow-up time is 29 +/- 18 months. All patients are asymptomatic. Echocardiography revealed either an intact septum (n = 4) or insignificant color jets at the apical portion of the septum (n = 1). The septal wall motion was preserved in 4 children and was hypokinetic in the fifth child.

CONCLUSIONS

This technique can be an additional tool to provide a secure closure of "Swiss cheese" defects even in the presence of associated cardiac lesions. Long-term consequences of this procedure on septal wall motion remain to be determined.

Apical muscular ventricular septal defects between the left ventricle and the right ventricular infundibulum. Diagnostic and interventional considerations

BACKGROUND

Effective transcatheter or surgical closure of apical muscular ventricular septal defects (VSDs) requires accurate delineation of variable and often complex anatomy. These defects have generally been considered as communications between the apexes of both left and right ventricles.

METHODS AND RESULTS

Among 50 consecutive patients with multiple muscular VSDs referred for transcatheter device closure between October 1987 and April 1993, a subset of 10 patients (aged 7 days to 28 years) with apical muscular VSDs shared a unique set of anatomic characteristics: (1) large and often single opening in the left ventricle; (2) multiple right ventricular openings in the anterior aspect of the apical septum; and (3) separation of the right ventricular apical region into which the VSDs open from the rest of the right ventricular inflow and outflow by prominent muscle bundles. Additional analysis of the anatomy by use of echocardiography and cineangiography showed that these muscular defects were between the left ventricular apex and right ventricular infundibular apex. In 6 patients, the transcatheter devices used to create a septum in these hearts were placed in the right ventricle, straddling muscle bundles that separated the apical VSD from the rest of the right ventricular inflow and outflow, resulting in incorporation of a portion of the right ventricular infundibular apex into the physiological left ventricle. Three patients had devices placed between the apexes of the left ventricle and the infundibulum. The defect closed spontaneously within the right ventricle in 1 patient. One patient died after surgery for tetralogy of Fallot in situs inversus. The remaining 9 patients were all clinically well at the time of their most recent follow-up visit (follow-up duration, 32 +/- 11 months). This distinct type of apical VSD was identified by echocardiography in 20 of 274 patients who were followed up clinically for muscular VSDs.

CONCLUSIONS

Left ventricular-infundibular apical VSDs constitute a distinct morphological type of muscular VSD that can be distinguished by echocardiography and cineangiography. In selected cases, the infundibular apex can be separated from the rest of the right ventricular inflow and outflow to eliminate flow across these defects.

Associated atrial septal defects increase perioperative morbidity after ventricular septal defect repair in infancy

Although closure of ventricular septal defects (VSDs) is currently associated with a relatively low risk, infants with associated atrial septal defects (ASDs) seem to have a higher perioperative morbidity. To clarify this impression, we reviewed our entire experience (since 1977) with closure of simple VSDs in 163 infants (age, < or = 12 months). Of these, 57 had significant ASDs (ASD-VSD subgroup). Hospital mortality was 3.7% (6/163) overall and 1.4% (2/145) since 1980. Actuarial survival at 10 years was 92% +/- 5%. Significant morbidity occurred in 15.5% (16/103) of the VSD subgroup versus 48.1% (26/54) of the ASD-VSD subgroup (p < or = 0.001). Multivariate analysis identified the presence of multiple VSDs and early date of operation as risk factors for hospital death, and younger age, an associated ASD, the size of the VSD, and use of hypothermic circulatory arrest as risk factors for significant perioperative morbidity. Compared with the VSD subgroup, the ASD-VSD subgroup had a higher hospital mortality (5.3% [3/57] versus 2.8% [3/106]), were younger (5.1 +/- 2.9 versus 7.2 +/- 2.9 months; p = 0.001), had a higher preoperative pulmonary artery pressure (70.2 +/- 19.0 versus 62.7 +/- 21.8 mm Hg; p = 0.08), needed more inotropic support (12.3% versus 3.7%; p = 0.07), needed more prolonged ventilation (3.3 versus 1.8 days; p = 0.02), and had longer postoperative hospital stays (11 versus 8 days; p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Three-dimensional reconstruction of ventricular septal defects: validation studies and in vivo feasibility

OBJECTIVES

The purpose of this study was to demonstrate the feasibility of in vivo three-dimensional reconstruction of ventricular septal defects and to validate its quantitative accuracy for defect localization in excised hearts (used to permit comparison of three-dimensional and direct measurements without cardiac contraction).

BACKGROUND

Appreciating the three-dimensional spatial relations of ventricular septal defects could be useful in planning surgical and catheter approaches. Currently, however, echocardiography provides only two-dimensional views, requiring mental integration. A recently developed system automatically combines two-dimensional echocardiographic images with their spatial locations to produce a three-dimensional construct.

METHODS

Surgically created ventricular septal defects of varying size and location were imaged and reconstructed, along with the left and right ventricles, in the beating heart of six dogs to demonstrate the in vivo feasibility of producing a coherent image of the defect that portrays its relation to surrounding structures. Two additional gel-filled excised hearts with defects were completely reconstructed. Quantitative localization of the defects relative to other structures (ventricular apexes and valve insertions) was then validated for seven defects in excised hearts. The right septal margins of the exposed defects were also traced and compared with their reconstructed areas and circumferences.

RESULTS

The three-dimensional images provided coherent images and correct spatial appreciation of the defects (two inlet, two trabecular, one outlet and one membranous Gerbode in vivo; one inlet and one apical in excised hearts). The distances between defects and other structures in the excised hearts agreed well with direct measures (y = 1.05x-0.18, r = 0.98, SEE = 0.30 cm), as did reconstructed areas (y = 1.0x-0.23, r = 0.98, SEE = 0.21 cm2) and circumferences (y = 0.97x + 0.13, r = 0.97, SEE = 0.3 cm).

CONCLUSIONS

Three-dimensional reconstruction of ventricular septal defects can be achieved in the beating heart and provides an accurate appreciation of defect size and location that could be of value in planning interventions.

The surgical anatomy of ventricular septal defects associated with overriding valvar orifices

This is the second review in a three-part series concerned with the description and categorization of ventricular septal defects. By viewing the defects from the right ventricular aspect, they can be placed into one of three classes: perimembranous, muscular, or doubly committed and juxta-arterial. According to the posteroinferior margin of the third group, these could extend to become perimembranous or muscular. In this review, the complications produced by malalignment of the septal structures associated with overriding of an arterial or atrioventricular valve are described in detail. It shows that although there are problems in defining the extent of any interventricular communication, these ventricular septal defects can be classified with the same categorization as developed for those not associated with overriding. The nosology developed is able to serve as a guide to the surgeon to the site of the specialized axis for atrioventricular conduction.

The surgical anatomy of ventricular septal defect

There is still no consensus as to how best to categorize and describe interventricular communications. In a series of three reviews, a system will be described showing how the anatomical criteria chosen for categorization will also serve as a guide for surgeons as to the location of the axis responsible for atrioventricular conduction tissue. In this first review, the defects described are not complicated by overriding of arterial or atrioventricular valves and are present in hearts that have basically normal segmental connections, or have some discordant connections (complete transposition or congenitally corrected transposition). The rims of the defect categorize the boundaries to which a surgeon may place a patch. Variations in these rims produce three classes of defect: perimembranous; muscular; and doubly committed and juxtaarterial (subarterial). The second part of the classification recognizes the further variation existing with respect to the component of the morphologically right ventricle into which the defect predominantly empties. Deficient atrioventricular septation can also lead to interventricular shunting in isolation, but the morphology is then quite different from hearts with simple deficiencies of the ventricular septum. We emphasize the abnormal location of the atrioventricular node in hearts with atrioventricular, as opposed to ventricular, septal defects.

Incidence and natural course of trabecular ventricular septal defect: two-dimensional echocardiography and color Doppler flow imaging study

This study was designed to determine the prevalence of trabecular ventricular septal defect (t-VSD) in neonates and to evaluate the effects of its location, morphologic features, and size on its natural course during infancy. One thousand twenty-eight term newborn infants were examined by color Doppler flow imaging with orthogonal ultrasonographic views. Ten girls and 11 boys (2.0%) were found to have t-VSD. The natural course of the defect was examined in 42 consecutive cases, consisting of this group of 21 neonates and another group of 21 neonates with t-VSD. The morphologic features of the defect within the trabecular septum were classified as one or two defects (36 cases) and as a mesh-like defect (six cases). Reduction in size began from the right ventricular side or from within the trabecular septum. Spontaneous closure occurred most commonly during the first 6 months of life and was observed in 32 cases (76%) by 12 months of age: the frequency of closure was not related to the morphologic features and the initial size of the defect, but apical defects tended to have higher persistent patency than did defects in other locations (p less than 0.05). We conclude that the frequency of t-VSD in neonates and the frequency of spontaneous closure during early infancy are higher than previously believed. This information is important for predicting the natural course of t-VSD and deciding on its proper management.