Ventricular Septal Defects 

Updated: Dec 10, 2015
Author: Prema Ramaswamy, MD; Chief Editor: Howard S Weber, MD, FSCAI 

Overview

Background

A ventricular septal defect (VSD) is a hole or a defect in the septum that divides the 2 lower chambers of the heart, resulting in communication between the ventricular cavities. A VSD may occur as a primary anomaly, with or without additional major associated cardiac defects. It may also occur as a single component of a wide variety of intracardiac anomalies, including tetralogy of Fallot (TOF), complete atrioventricular (AV) canal defects, transposition of great arteries, and corrected transpositions.

In this article, the term ventricular septal defect refers to an isolated VSD, or a defect in a heart with AV concordance. That is, the atria are attached to the correct ventricle and the normally related arteries (great arteries arising from the appropriate ventricle [ie, an otherwise normal heart]), with no other major lesions. An isolated VSD occurs in approximately 2-6 of every 1000 live births and accounts for more than 20% of all congenital heart diseases. After bicuspid aortic valves, VSDs are the most commonly encountered congenital heart defects.

VSDs were first clinically described by Roger in 1879[1] ; the term maladie de Roger is still used to refer to a small asymptomatic VSD. In 1898, Eisenmenger described a patient with VSD, cyanosis, and pulmonary hypertension. This combination has been termed the Eisenmenger complex. Pulmonary vascular disease and cyanosis in combination with any other systemic-to-pulmonary connection has been called the Eisenmenger syndrome.[2]

Heath and Edwards described the morphologic changes associated with pulmonary vascular disease in 1958, and their 6 categories of vascular change have remained the standard of comparison up to the present day.[3]

The symptoms and physical findings associated with ventricular septal defects (VSDs) depend on the size of the defect and the magnitude of the left-to-right shunt, which, in turn, depends on the relative resistances of the systemic and pulmonary circulations (see Presentation).

Chest radiography, magnetic resonance imaging (MRI), and electrocardiography (ECG) may all provide useful information in the workup of a VSD. Although cardiac catheterization was a standard part of the evaluation in the past, detailed echocardiography is now the diagnostic imaging modality of choice (see Workup).

Children with small VSDs are asymptomatic and have an excellent long-term prognosis. Neither medical therapy nor surgical therapy is indicated. In children with moderate or large VSDs, medical therapy is indicated to manage symptomatic congestive heart failure (CHF) because some VSDs may become smaller with time, although uncontrolled CHF symptoms with growth failure is an indication for surgical repair. Neither the age nor the size of the patient is prohibitive in considering surgery (see Treatment).

For patient education resources, see the Heart Health Center, as well as Tetralogy of Fallot and Ventricular Septal Defect.

 

Anatomy

VSD is a developmental defect of the interventricular septum, wherein communication between the cavities of the 2 ventricles is observed. Since 1979, real-time 2-dimensional (2D) echocardiography has dramatically improved the noninvasive anatomic assessment of ventricular septal defect.

Embryology

At 4-8 weeks’ gestation, the single ventricular chamber is effectively divided into 2 chambers. This division is accomplished with the fusion of the membranous portion of the interventricular septum, the endocardial cushions, and the bulbous cordis (the proximal portion of the truncus arteriosus).

The muscular portion of the interventricular septum grows cephalad as each ventricular chamber enlarges, eventually meeting with the right and left ridges of the bulbous cordis. The right ridge fuses with the tricuspid valve and the endocardial cushions, separating the pulmonary valve from the tricuspid valve. The left ridge fuses with a ridge of the interventricular septum, leaving the aortic ring in continuity with the mitral ring.

The endocardial cushions develop concomitantly and finally fuse with the bulbar ridges and the muscular portion of the septum. The fibrous tissue of the membranous portion of the interventricular septum makes the final closure and separates the 2 ventricles.

Structure of interventricular septum

The interventricular septum is a curvilinear complex structure that can be divided into 4 zones on the basis of anatomic landmarks in the right ventricle (RV).

The RV has many heavy trabeculations. The stoutest of these is a Y-shaped bundle known as the trabecula septomarginalis, which proceeds toward the apex and which gives rise to the moderator band that courses transversely near the apex. The trabecula septomarginalis is an important structure that helps in identifying the RV, regardless of its location in the chest. The 2 limbs of the Y travel superiorly, with the anterior (parietal) limb supporting the pulmonic valve and the posterior limb (septal band) extending to the membranous septum.

The 4 parts of the interventricular septum are as follows (see the image below)[4] :

  • Inlet septum - This region is smooth-walled and extends from the septal attachments of the tricuspid valve to the distal attachments of the tricuspid tensor apparatus; it is also called the AV canal septum

  • Trabecular septum - This apical trabecular zone separates the coarse trabeculations of the RV from the fine ones seen in the left ventricle (LV); it is also known as the muscular septum or the ventricular sinus septum

  • Outlet (infundibular) septum - This smooth-walled region is separated from the trabeculated portion of the RV by the septal band of the trabecula marginalis; it is also referred to as the parietal band or the distal conal septum, and defects in this area may be termed conal septal defects

  • Membranous septum - This region, the last and the smallest part of the interventricular septum, lies between the anterior and the septal tricuspid leaflets and below the right and the noncoronary cusps of the aortic valve

    A: Image shows a ventricular septum viewed from th A: Image shows a ventricular septum viewed from the right side. It has the following 4 components: inlet septum from the tricuspid annulus to the attachments of the tricuspid valve (I); trabecular septum from inlet to apex and up to the smooth-walled outlet (T); outlet septum, which extends to the pulmonary valve (O); and membranous septum. B: Anatomic positions of the defects are as follows: outlet defect (a); papillary muscle of the conus (b); perimembranous defect (c); marginal muscular defects (d); central muscular defects (e); inlet defect (f); and apical muscular defects (g).

The 3 muscular components of the interventricular septum described above abut on the membranous septum and fan out from it as triangles, with the apices touching this septum.

In the normal heart, the tricuspid and mitral valves are attached to the ventricular septum at different levels, so that the tricuspid-valve attachment is apically displaced relative to the mitral-valve attachment. Therefore, a portion of the interventricular septum, called the AV septum, lies between the right atrium (RA) and the LV. This portion consists of a membranous part anteriorly and a muscular part posteriorly and is usually present in most hearts with an isolated VSD.

In the anterior aspect, the tricuspid-valve attachment divides the area of membranous septum into an interventricular component (between the LV and the RV) and an AV component (between the LV and the RA). When a VSD is isolated, the AV component of membranous septum is usually intact.

Classifications of ventricular septal defects

Many classifications of VSDs have been proposed. The following is a summary of an underlying classification that is surgically and clinically useful (see the image below).

Schematic representation of the location of variou Schematic representation of the location of various types of ventricular septal defects (VSDs) from the right ventricular aspect. A = Doubly committed subarterial ventricular septal defect; B = Perimembranous ventricular septal defect; C = Inlet or atrioventricular canal-type ventricular septal defect; D = Muscular ventricular septal defect.

Perimembranous (infracristal, conoventricular) VSDs lie in the LV outflow tract just below the aortic valve. Because they occur in the membranous septum with defects in the adjacent muscular portion of the septum, they are subclassified as perimembranous inlet, perimembranous outlet, or perimembranous muscular. These are the most common types of VSD and account for 80% of such defects.

Perimembranous VSDs are associated with pouches or aneurysms of the septal leaflet of the tricuspid valve, which can partially or completely close the defect. In addition, an LV-to-RA shunt may be associated with this defect.

Supracristal (conal septal, infundibular, subpulmonic, subarterial, subarterial doubly committed, outlet) VSDs account for 5-8% of isolated VSDs in the United States but 30% of such defects in Japan. These defects lie beneath the pulmonic valve and communicate with the RV outflow tract above the supraventricular crest and are associated with aortic regurgitation secondary to the prolapse of the right aortic cusp.

Muscular VSDs (trabecular) are entirely bounded by the muscular septum and are often multiple. The term Swiss-cheese septum has been used to describe multiple muscular VSDs. Other subclassifications depend on the location and include central muscular or midmuscular, apical, and marginal (when the defect is along the RV-septal junction). These VSDs account for 5-20% of all defects. Any single defect observed from the LV aspect may have several openings on the RV aspect.

Posterior (canal-type, endocardial cushion–type, AV septum–type, inlet, juxtatricuspid) VSDs lie posterior to the septal leaflet of the tricuspid valve. Although the locations of posterior VSDs are similar to those of VSDs observed with AV septal defects, they are not associated with defects of the AV valves. About 8-10% of VSDs are of this type.

Other anatomic considerations

The relation of the AV conduction pathways to the defect is important for surgical repair. The AV node occupies the apex of the triangle of Koch, which is limited posteriorly by the tendon of Todaro, inferiorly by the os of the coronary sinus, and superiorly by the tricuspid valve annulus. The bundle of His arises from the AV node.

In perimembranous defects, the bundle of His lies in a subendocardial position as it courses along the posterior-inferior margin of the defect. In inlet defects, the bundle of His passes anterosuperiorly to the defect. In muscular VSDs and outlet defects, the risk of heart block is minimal because the bundle is remote from the defect.

Patients with subpulmonary conal defects usually have deficiency of muscular or fibrous support below the aortic valve with subsequent herniation of the right aortic leaflet. However, in patients with perimembranous VSDs and aortic insufficiency, it may be the right or the noncoronary cusp that prolapses.

Pathophysiology

A defect in the interventricular septum allows communication between the systemic and pulmonary circulations. As a result, flow moves from a region of high pressure to a region of low pressure—that is, from the LV to the RV (a left-to-right shunt). The pathophysiologic effects of a VSD derive from the hemodynamic effects secondary to a left-to-right shunt and from changes in the pulmonary vasculature.

Left-to-right shunt

A left-to-right shunt at the ventricular level has 3 hemodynamic consequences:

  • Increased LV volume load

  • Excessive pulmonary blood flow

  • Reduced systemic cardiac output

  • Elevated pulmonary artery pressures

Blood flow through the defect from the LV to the RV results in oxygenated blood entering the pulmonary artery (PA). The addition of this extra blood to the normal pulmonary flow from the vena cava increases blood flow to the lungs and subsequently increases pulmonary venous return into the left atrium (LA) and ultimately into the LV. This increased LV volume results in LV dilatation and then hypertrophy. It increases end-diastolic pressure and consequently LA pressure, then raises pulmonary venous pressure.

The increased pulmonary blood flow raises pulmonary capillary pressure, which can increase pulmonary interstitial fluid. When this condition is severe, patients can present with pulmonary edema. Therefore, both PA pressure and pulmonary venous pressure are elevated in a VSD. The increase in pulmonary venous pressure is not seen with an atrial septal defect: LA pressures are low because as blood can readily exit from this chamber through the atrial communication.

Finally, as blood is shunted through the VSD away from the aorta, cardiac output decreases, and compensatory mechanisms are stimulated to maintain adequate organ perfusion. These mechanisms include increased catecholamine secretion and salt and water retention by means of the renin-angiotensin system.

The degree of the left-to-right shunt determines the magnitude of the changes described above. The left-to-right shunt depends on 2 factors, of which one is anatomic and the other physiologic.

The anatomic factor is the size of the VSD. (The location of the VSD is irrelevant in terms of the degree of the shunt.) In a normal heart, RV pressure is about 25-30% that of the LV. In a large VSD, this pressure difference is no longer maintained, because a large hole offers no resistance to blood flow. Consequently, these defects are called nonrestrictive VSDs.

However, in a small VSD, the normal pressure difference between the ventricles is maintained. These defects are called restrictive VSDs because blood flow across the defects is restricted, so that the normal pressure difference is maintained.

The physiologic factor is the resistance of the pulmonary vascular bed.

Changes in pulmonary vasculature

The terms pulmonary hypertension, high pulmonary resistance, and pulmonary vascular disease are often confused. Pulmonary hypertension merely indicates a high blood pressure in the pulmonary circuit; depending on the duration, it may be reversible. Pulmonary resistance is a function of numerous factors, including age, altitude, hematocrit, and diameter of the pulmonary arterioles.

A neonate has increased resistance secondary to the increase in the media of the pulmonary arterioles; this decreases the effective diameter of the vessels. In addition, neonates have a relative polycythemia. The elevated pulmonary resistance usually declines to adult levels by 6-8 weeks.

Pulmonary vascular disease is ultimately an irreversible condition and may occur over time in individuals with a large left-to-right shunt. It may also occur in the absence of a shunt; this condition is called primary pulmonary hypertension. A characteristic series of histologic changes ranging from grade I to grade VI has been described.[3] The ultimate consequences of pulmonary vascular obstructive disease are irreversible vascular changes and pulmonary resistance equal to or exceeding systemic resistance.

Natural history

The natural history of VSD has a wide spectrum and is directly proportional to the size of the defect, ranging from spontaneous closure to congestive heart failure (CHF) or the development of pulmonary vascular disease without heart failure symptoms.

Spontaneous closure frequently occurs in children, usually by age 2 years. Closure is uncommon after age 4 years. Closure is most frequently observed in muscular defects (80%), followed by perimembranous defects (35-40%). Outlet VSDs have a low incidence of spontaneous closure, and inlet VSDs do not close.

Closure may occur by means of hypertrophy of the septum, formation of fibrous tissue, subaortic tags, apposition of the septal leaflet of the tricuspid valve, or (in rare cases) prolapse of a leaflet of the aortic valve. When perimembranous VSDs close because of development of fibrous tissue or the apposition of the tricuspid valve, an aneurysm of the interventricular septum may appear.

A small VSD that does not spontaneously close is associated with an excellent prognosis. Patients are theoretically at risk for infective endocarditis, but small muscular VSDs pose no other adverse possibilities.

Small perimembranous VSDs, however, are associated with an increased risk of prolapse of the aortic cusp over time. In addition, a small but definite risk of malignant ventricular arrhythmia was reported in the Second Natural History Study.[5] This study group consisted of about 1000 patients (about 76% of the original cohort). The original cohort was the First Natural History Study, which included 1280 patients (mostly children) with VSDs admitted after cardiac catheterization between 1958 and 1969.

Wu et al reported a 45% incidence of LV-to-RA shunts and a 6% incidence of subaortic ridges during a 20-year follow-up of about 900 patients with perimembranous VSDs.[6] This group later reported an increased incidence of infective endocarditis in patients who had LV-to-RA shunts.[7]

Etiology

For the purposes of etiologic analysis, clustering the defect types mentioned earlier (see Anatomy) according to potential pathogenic mechanisms is beneficial. The following pathologic classification allows comparison of similar defects:

  • Subarterial VSDs can be classified as abnormalities of ectomesenchymal tissue migration

  • Perimembranous VSDs can be classified as abnormalities of intracardiac blood flow

  • Muscular VSDs can be classified as abnormalities in cell death

  • Type III inflow VSDs can be classified as abnormalities of the extracellular matrix and defects in the endocardial cushion

At present, a multifactorial etiology based on an interaction between hereditary predisposition and environmental influences is assumed to cause the defects. The following questions have relevance to children, their family, and their parents alike:

  • What caused a child’s heart defect?

  • What is the risk that other children and grandchildren in the family will have a heart defect?

Maternal factors

Maternal diabetes has long been recognized as a risk factor for congenital cardiovascular malformations (CCVMs). The risk of CCVMs remains high for infants of women with poorly controlled elevated phenylalanine levels.

No population-based data are available to define the range of risk alcohol consumption poses to the developing cardiovascular system. Investigators from the Baltimore-Washington Infant Study (BWIS) reported that maternal alcohol consumption was associated with only muscular ventricular septal defect.[8]

Genetic risk factors

The single largest determinant in the BWIS data set is the presence of a genetic risk factor defined as a previous occurrence of a congenital cardiovascular defect in the family. A family history of a cardiac or noncardiac defect in either a parent or a preceding sibling is a major risk factor.

The incidence of VSD in siblings of patients with the same malformation is about 3 times that of the general population. VSDs have been reported in identical twins, but the frequency of discordance is high, even in identical twins.

Familial congenital heart defects are often concordant by phenotype and developmental mechanism. Among cases with VSDs, previous occurrence of transposition, tetralogy of Fallot (TOF), and truncus arteriosus is higher than expected.

Genotype-phenotype correlation

The challenge for the next generation of pediatric cardiologists is to collaborate with geneticists to define genotype-phenotype correlations.

Regarding genetic counseling and prospects for prevention, the single greatest change in counseling regarding the recurrence risk for CCVMs is the recognition of familial and chromosomally based defects see the Table below). Thorough evaluation includes the following:

  • An accurate clinical diagnosis of the cardiovascular defect(s) organized in a hierarchy (this is necessary to specify the type of VSD)

  • Carefully detailed noncardiac defects

  • Careful family history of first-degree and second-degree relatives, including detailed analysis of pregnancy loss, racial origin, and consanguinity

  • A search for risk factors, such as gestational diabetes mellitus

Table. Aneuploid Syndromes Associated with Ventricular Septal Defect (Open Table in a new window)

Syndrome

CCVM (%)

Type of CCVM

Del 4q, 21, 32

60

Ventricular septal defect, atrial septal defect

Del 5p

30-60

Ventricular septal defect

Trisomy 13

80

Atrial septal defect, ventricular septal defect, TOF

Trisomy 18, Edwards syndrome

100

Ventricular septal defect, TOF, double-outlet right ventricle (DORV)

Trisomy 21, Down syndrome

40-50

Ventricular septal defect, atrioventricular canal (AVC)

Del 22q11, DiGeorge syndrome (single gene etiology, autosomal dominant)

50

Truncus arteriosus, TOF, ventricular septal defect

Epidemiology

United States statistics

VSDs affect 2-7% of live births. The patient’s area of residence may influence the prevalence of known VSDs. For example, small muscular VSDs are most likely to be identified in urban locations, possibly because of ready access to sophisticated healthcare in these locations.

An echocardiographic study revealed a high incidence of 5-50 VSDs per 1000 newborns. The defects in this study were small restrictive muscular VSDs, which typically spontaneously close in the first year of life.[9]

VSDs are the most common lesion in many chromosomal syndromes, including trisomy 13, trisomy 18, trisomy 21, and relatively rare syndromes. However, in more than 95% of patients with VSDs, the defects are not associated with a chromosomal abnormality.

Sex-related demographics

VSDs are slightly more common in female patients than in male patients (56% vs 44%). The incidence of abnormalities of ectomesenchymal tissue migration (ie, subarterial outlet VSD) is highest in boys.

Race-related demographics

Reports are inconclusive regarding racial differences in the distribution of VSDs. However, the doubly committed or outlet defect occurs is most common in the Asian population. These constitute 5% of the defects in the Unites States but 30% of those reported in Japan.

Prognosis

Children with small VSDs are asymptomatic and have excellent long-term prognoses. The outcome of medical therapy for children with moderate or large VSDs varies, as follows.

Many infants improve, showing evidence of a gradual decrease in the magnitude of the left-to-right shunt between the ages of 6 and 24 months. It is important to assess the cause of the decrease in left-to-right flow, which can reflect an increase in pulmonary vascular resistance (PVR), a decrease in the relative size of the defect, or the development of RV outflow tract hypertrophy, resulting in functional or anatomic obstruction.

Most children with VSDs remain in stable condition or improve after infancy. Heart failure rarely occurs after infancy. Anemia, respiratory infection, endocarditis, or the development of an associated lesion (eg, aortic insufficiency) can trigger a recurrence of symptoms.

A few patients who develop severe pulmonary vascular obstructive disease with predominant right-to-left shunts (Eisenmenger syndrome) at the time of referral require symptomatic therapy. Cyanosis progressively increases, and exercise capacity decreases. Select patients with large VSDs may be candidates for lung or heart-lung transplantation.

Red blood cell (RBC) reduction by means of partial-exchange transfusion may relieve symptoms associated with extreme polycythemia (eg, headache, extreme fatigue).

The surgical mortality is less than 1% for isolated VSDs. 

Complications

Eisenmenger complex is the most severe complication of a large VSD. Fixed and irreversible pulmonary hypertension develops, resulting in reversal of the left-to-right shunt to a right-to-left shunt.

Secondary aortic insufficiency is associated with prolapse of aortic valve leaflets. It is rare in children younger than 2 years. This complication is observed only in 5% of patients with VSD. The incidence is higher in supracristal VSDs than in perimembranous VSDs.

The development of aortic regurgitation in association with doubly committed subarterial VSD is a well-known phenomenon. Aortic regurgitation is due to a poorly supported right coronary cusp combined with the Venturi effect produced by the VSD jet, resulting in cusp prolapse.

Right ventricular (RV) outflow tract obstruction was noted in 7% of a large cohort of VSD in France.[10]  The investigators noted the obstruction to be infundibular. A later angiocardiographic study showed that the obstruction was most often secondary to anomalous muscle bundles and only rarely infundibular.[11]

Discrete fibrous subaortic stenosis is occasionally associated with a VSD. This complication is most often reported with perimembranous VSDs and can first appear after either spontaneous or surgical closure. Zielinsky et al concluded that anterior or posterior malalignment of the outlet or the conal septum is present in all patients with a VSD who develop discrete subaortic stenosis.[12]

Infective endocarditis is rare in children younger than 2 years. In the presence of infective endocarditis in the pulmonary circulation, it is important to record the patient’s history meticulously and to investigate the left-to-right shunt by means of echocardiography. With VSDs, both the systemic and pulmonary circulation may be affected; hence, vegetation manifests on both sides.

Embolization is expected despite the morphology of the vegetation. In general, vegetation more than 10 mm, particularly if pedunculated, should be regarded as an indication for surgical intervention, even in the absence of symptoms.

Infection is usually located at the ridge of the VSD itself or on the tricuspid or pulmonary valve leaflets.

Intramural VSD, in which interventricular communications occur through right ventricular free wall trabeculations, may occur following biventricular repair of conotruncal anomalies.[13] These types of VSDs have an associated postoperative morbidity, mortality, and longer postoperative hospital stays.[13]

 

Presentation

History

The symptoms and physical findings associated with ventricular septal defects (VSDs) depend on the size of the defect and the magnitude of the left-to-right shunt. The defects observed in adult patients are usually small or medium-sized because the vast majority of patients with isolated large defects come to medical and, often, surgical attention early in life.

Small VSDs

Typically, patients have mild or no symptoms. These infants are most often brought to the cardiologist’s attention because a murmur is detected during routine examination. Feeding or weight gain usually is not affected.

Moderate VSDs

Babies may have excessive sweating as a consequence of increased sympathetic tone. This sweating is especially notable during feeds. An important symptom is fatigue with feeding. Because feeding results in a need for increased cardiac output, this activity may unmask exercise intolerance in a baby. Rapid breathing (tachypnea) at rest or with feedings is usually present.  

A sensitive sign may be the lack of adequate growth, which is due to an increased caloric requirement and an inability of the infant to feed adequately. Frequent respiratory infections may occur secondary to the pulmonary congestion.

Symptoms, which begin as pulmonary vascular resistance (PVR) decreases, may be clearly apparent by age 2-3 months. They tend to occur earlier in premature infants than in full-term infants because PVR decreases earlier in the former than in the latter.

Large VSDs

Symptoms and signs are similar to, but more severe than, those observed in infants with moderate defects. Symptoms may be occur later or, rarely, not at all, because of a delayed or no significant decrease in pulmonary vascular resistance. Poor weight gain and frequent respiratory infections are common.

Eisenmenger syndrome, or VSD with severe pulmonary vascular disease

At rest, patients may have no symptoms with mild systemic desaturation. With exercise, symptoms include exertional dyspnea, cyanosis, chest pain, syncope, and hemoptysis.

Physical Examination

In a patient with small VSDs, physical findings consist primarily of cardiac manifestations. In patients with moderate-to-large defects, growth may be affected to the point where abnormalities are apparent on general examination.

The axiom “the louder the murmur, the smaller the defect” does not always apply. The murmurs heard in early infancy, which disappear by age 1 year, probably represent spontaneous closure of the defects. The recognition of the diastolic murmur of aortic insufficiency, in the presence of classic findings of VSD, should make the diagnosis of supracristal variety likely.

Small VSDs

Patients may have normal vital signs. Physiologic splitting of S2 is usually retained. The characteristic harsh, holosystolic murmur is loudest along the lower left sternal border (LSB), and it is well localized. Small defects can produce a high-pitched or squeaky noise. The murmur is usually detected after the PVR decreases by age 4-8 weeks.

Moderate VSDs

Infants often have a normal length and decreased weight. Poor weight gain is a sensitive indicator of congestive heart failure (CHF). Infants may have mild tachypnea, tachycardia, and an enlarged liver. The precordial activity is accentuated.

The murmur with moderate-sized defects is usually associated with thrill. A holosystolic harsh murmur is most prominent over the lower LSB. The intensity of the pulmonary component is usually normal or slightly increased. In addition to the harsh holosystolic murmur, a diastolic rumble may be detected in the mitral area. This rumble suggests functional mitral stenosis secondary to a large left-to-right shunt and indicates a surgical-level shunt (pulmonary-to-systemic flow ratio [Qp:Qs] greater than 2:1)

Large VSDs

As with moderate defects, signs of CHF are usually present. The cardinal signs of heart failure include tachycardia, tachypnea, and hepatomegaly. In addition, cardiomegaly is present and helps in differentiating heart failure from a respiratory condition (eg, bronchiolitis). The murmur is usually short, nonspecific, and poorly localized with an associated diastolic rumble. A loud single second heart sound at the upper left sternal border is also characteristic. 

A VSD is not typically associated with cyanosis: it is a “pink” condition. Thus, persistent cyanosis from birth indicates a more complicated lesion than isolated VSD. The occurrence of cyanosis after infancy suggests reversal of the shunt. Patients with large VSDs and marked elevations of PVR frequently appear well in childhood because the blood flow in their systemic and pulmonary circuits is well balanced.

Eisenmenger syndrome, or VSD with severe pulmonary vascular disease

Children with Eisenmenger syndrome may have tachypnea only with exercise and not at rest. They may be only mildly cyanotic at rest but then develop profound cyanosis with exercise.

 

DDx

Diagnostic Considerations

In addition to the conditions listed in the differential diagnosis of ventricular septal defect (VSD), other problems to be considered include the following:

  • VSD with associated defects

  • Atrioventricular (AV) septal defect

  • Double-outlet right ventricle (RV) with normally related great arteries

  • Mild or moderate subaortic stenosis

Differential Diagnoses

 

Workup

Approach Considerations

Chest radiography, magnetic resonance imaging (MRI), and electrocardiography (ECG) may all provide useful information in the workup of a ventricular septal defect (VSD).

Although cardiac catheterization was a standard part of the evaluation of a VSD in the past, detailed echocardiography is now the procedure of choice. Echocardiography provides the information required for surgical closure. Cardiac catheterization is used primarily in the following 2 settings:

  • Pulmonary hypertension of unknown reactivity

  • A small-to-moderate defect with only mild left ventricular (LV) enlargement; in this setting, cardiac catheterization is useful for definitively assessing the pulmonary-to-systemic flow ratio (Qp:Qs), which can assist decision making regarding the need for surgery (though MRI can provide this information noninvasively)

An experienced pediatric cardiologist can accurately assess newly referred patients with murmurs on clinical examination with a sensitivity of 96% and a specificity of 95%.

Cardiac biomarkers may have utility in evaluating the clinical condition of pediatric patients with congenital heart disease and congestive heart failure.[14] Sugimoto et al found that troponin I and amino-terminal procollagen type III peptide (PIIIP) levels are elevated in children with atrial septal defects (ASDs) and VSDs. PIIIP levels are also elevated in patients with pulmonary stenosis and tetralogy of Fallot. Moreover, levels of B-type natriuretic peptide (BNP)/N-terminal proBNP had a good correlation with pediatric heart failure scores.[14]

Radiography

Chest radiography may reveal the following:

  • Small VSDs

  • Normal heart size

  • Normal pulmonary vascularity

  • Moderate or large VSDs

  • Increased cardiac silhouette

  • Increased pulmonary vascular markings with a prominent main pulmonary artery (PA) segment

  • Enlarged left atrium (LA), which is visible on lateral radiographs

  • Large VSDs with markedly increased pulmonary vascular resistance (PVR)

  • Essentially normal-sized heart

  • Right ventricular (RV) hypertrophy with the cardiac apex rotated slightly upward, to the left, and posteriorly

  • Markedly prominent main PA and adjacent vessels

  • Decreased pulmonary vascularity in the outer third of the lung fields

Echocardiography

Two-dimensional echocardiography, with Doppler echocardiography and color flow imaging, can be used to determine the size and location of virtually all VSDs. Doppler echocardiography provides additional physiologic information (eg, RV pressure, PA pressure, and interventricular pressure difference).

Measurement of LA and LV diameters provides semiquantitative information about shunt volume. The size of the defect is often expressed in terms of the size of the aortic root. Defects that approximate the size of the aortic root are classified as large; those that are one third to two thirds of the diameter of the aorta are classified as moderate; and those that are less than one third of the aortic root diameter are classified as small.

The precise location and size of a VSD can be determined by combining subcostal views and apical 4-chamber views with parasternal short-axis and long-axis views (see the images below).

Apical 4-chamber views. A: Image shows a large inl Apical 4-chamber views. A: Image shows a large inlet defect. The defect is posterior and at the level of the atrioventricular valves. B: Image shows a small midmuscular ventricular septal defect. LA = Left atrium; LV = Left ventricle; PA = Pulmonary artery; RA = Right atrium; RV = Right ventricle.
Supracristal ventricular septal defect (VSD). Top Supracristal ventricular septal defect (VSD). Top image: Parasternal long-axis view shows the defect just below the aortic root. Middle image: The plane of sound is tilted to view the right ventricular outflow tract, and the defect is observed below the pulmonic valve. Bottom image: Parasternal short-axis view shows the ventricular septal defect between the aortic root (Ao) and the pulmonic valve (PV). LA = Left atrium; LV = Left ventricle; PA = Pulmonary artery; RA = Right atrium; RV = Right ventricle.
Echocardiogram of a child with a perimembranous ve Echocardiogram of a child with a perimembranous ventricular septal defect (VSD). Note the defect at the 10 o'clock position in the parasternal short-axis view. AO = Aortic root; LA = Left atrium; LV = Left ventricle; PA = Pulmonary artery; RA = Right atrium; RV = Right ventricle.

Varying approaches are recommended for different types of VSDs, as follows:

  • Perimembranous subaortic VSD – These are best imaged by using the subcostal approach with anterior angulation

  • Supracristal VSDs – These are best observed on parasternal long-axis and short-axis views and on sagittal subcostal views; when prolapse of the right aortic cusp obscures the VSD, color Doppler echocardiography is invaluable in defining the location and size of the defect and the degree of secondary aortic incompetence

  • Muscular VSDs – For these, all views that show the ventricular septum must be used; color Doppler echocardiography is critical for determining small defects

  • Inlet or atrioventricular (AV) canal–type VSD - These are best observed on apical 4-chamber views

Transesophageal echocardiography (TEE) is occasionally used. In the pediatric age group, it is most often used intraoperatively to assess the completeness of the repair.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a useful adjunct tool, but it is infrequently required for the diagnosis of VSDs. As a rule, it is employed only when ultrasonography is not feasible or when ultrasonographic findings are not diagnostic.

However, because MRI data about systemic and pulmonary flows are been well validated and well correlated with catheterization data, one of the indications for the use of MRI is evaluation of a VSD that is judged to be borderline during echocardiography in terms of the level of the left-to-right shunt. For such defects, an MRI-derived Qp:Qs may assist the clinician in making the decision whether to proceed with surgical treatment.

Electrocardiography

In patients with small VSDs, ECG findings are normal.

In patients with moderate-sized VSDs and with moderate or large left-to-right shunts with volume overload in the LV, LV hypertrophy is the rule. Combined ventricular hypertrophy is common. This may manifest as a large equiphasic midprecordial voltage (> 50 mm) in the midprecordial leads, an event known as the Katz-Wachtel phenomenon. Inlet defects may be associated with left-axis deviation of the frontal plane QRS with Q waves in leads I and aVL.

In patients with large VSDs and equal ventricular pressures, RV hypertrophy is demonstrated as a dominant R wave in the right precordial leads and upright T waves in younger patients. In patients with increased pulmonary blood flow, LA dilatation is evidenced by biphasic P waves in leads I, aVR, and V6, with prominent negative deflection in V1.

 

Treatment

Approach Considerations

Children with small ventricular septal defects (VSDs) are asymptomatic and have an excellent long-term prognosis. Neither medical therapy nor surgical therapy is indicated. Prophylactic antibiotic therapy against endocarditis is no longer indicated in most cases. For more information, see the American Heart Association recommendations for Antibiotic Prophylaxis for Infective Endocarditis. Maintenance of good oral hygiene is of paramount importance in reducing the risk of endocarditis.

In children with moderate or large VSDs, medical therapy is indicated to manage symptomatic congestive heart failure (CHF) because some VSDs may become smaller with time.

Uncontrolled CHF with growth failure and recurrent respiratory infection is an indication for immediate surgical repair. Neither the age nor the size of the patient is prohibitive in considering surgery.

Large, asymptomatic defects associated with elevated pulmonary artery (PA) pressure are often repaired when infants are younger than age 6-12 months. Surgical repair is indicated in older asymptomatic children with a normal pulmonary pressure if the pulmonary-to-systemic flow ratio (Qp:Qs) is large enough to result in left ventricular dilatation on echocardiography.

Prolapse of an aortic valve cusp is an indication for surgery even if the VSD is small. Early repair may prevent progression of the aortic valve insufficiency.

Early surgical repair (younger than age 1 year) of VSD appears to lead to a significant postsurgical acceleration of growth within 3-6 months in term and preterm infants and, thus, a favorable growth pattern.[15] However, patients who undergo a rapid postsurgery catch-up growth after a period of failure to thrive may have an increased risk of insulin resistance, metabolic syndrome, obesity, and cardiovascular disease.[15]

Elevated pulmonary vascular resistance may be maintained in some patients despite VSD closure and may, in fact, represent a primary disease of the pulmonary vessels.

Medical Management of Symptomatic CHF

Therapies used to manage symptomatic congestive heart failure (CHF) in children with moderate or large ventricular septal defects (VSDs) may include the following:

  • Increased caloric density of feedings to ensure adequate weight gain - Occasionally, oral feeds must be supplemented with nasogastric tube feedings, because a baby in CHF may be unable to consume adequate calories for appropriate weight gain

  • Diuretics (eg, furosemide) to relieve pulmonary congestion - Furosemide is usually given in a dosage of 1-3 mg/kg/d divided in 2 or 3 doses; long-term furosemide treatment results in hypercalciuria, renal damage, and electrolyte disturbances

  • Angiotensin-converting enzyme (ACE) inhibitors (eg, captopril and enalapril) - These medications reduce both the systemic and pulmonary pressures (the former to a greater degree), thereby reducing the left-to-right shunt

  • Digoxin (5-10 µg/kg/d) - This may be indicated if diuresis and afterload reduction do not relieve adequately symptoms, although the data regarding efficacy of this drug in this particular situation are controversial.  

Intracardiac Repair of Defect

The first operation described for the treatment of a VSD was a palliative one and involved placing a restrictive band across the main PA.[16] This approach was proposed because pulmonary vascular disease as a result of unimpeded flow to the lungs was recognized as a dreaded complication of a VSD. The procedure was popular for about 2 decades because it was associated with low mortality and morbidity.

The first intracardiac repair of a VSD was performed in 1954 by Lillehei et al, who used a parent as an oxygenator and a pump in controlled cross-circulation.[17] The current techniques of hypothermia and cardiopulmonary bypass were first reported in the 1970s.[18, 19, 20]

Surgical closure

At present, direct surgical repair using cardiopulmonary bypass is the preferred surgical therapy in most centers. PA banding, part of a 2-stage procedure, is largely reserved for critically ill infants with multiple VSDs or for those with associated anomalies.

Most perimembranous and inlet VSDs are repaired via a transatrial surgical approach. Defects in the outlet septum are approached through the pulmonary valve. Multiple muscular defects, especially near the apex, pose a difficult problem. Initial pulmonary banding or left ventricular (LV) approach through an apical left ventriculotomy and closing the defect with a single patch are the standard techniques.

Transcatheter therapy (see below) remains an experimental approach. A hybrid operation is a joint procedure involving the interventional cardiologist and the cardiac surgeon. This approach may be used for multiple VSDs where the perimembranous VSD is repaired surgically and the muscular VSDs are closed with a transcatheter device.

Transcatheter closure

Muscular VSDs have been closed with transcatheter devices for the past 15 years. Perimembranous VSDs, though relatively common, can be difficult to close percutaneously. With previous devices (eg, Rashkind or button devices), attempts to close this type of VSD have been unsuccessful, because of the proximity of the defects to the aortic valve resulting in potential aortic valve damage.

The Amplatzer membranous VSD occluder (AGA Medical Corporation; Golden Valley, Minnesota), has undergone phase I trials in the United States. This device is an asymmetric, self-expandable, double-disk unit. Current recommendations are to use this device in older patients who weigh more than 8 kg and who have a subaortic rim of more than 2 mm.

Most procedures are performed with the patient under general anesthesia and with transesophageal echocardiographic guidance. Reported complications have included aortic and tricuspid regurgitation, device embolization, complete heart block, transient left bundle-branch block (LBBB), hemolysis, small residual shunts, and perforation.

In a phase I study, Fu et al reported 3 adverse events of complete heart block, perihepatic bleeding, and rupture of tricuspid valve chordae tendineae.[21] In a previous article, they reported 2 cases of transient heart block that responded to high-dose steroids.[22] Subsequent studies found that the Amplatzer membranous VSD occluder resulted in excellent closure rates but had an unacceptably high rate of complete heart block.[23, 24]

Complications

A murmur of a residual VSD is not infrequent. Selective use of intraoperative transesophageal echocardiography (TEE) to assess closure may be useful. Decisions regarding reoperation are based on symptoms, left heart size, pulmonary pressure, and degree of shunting.

Right bundle branch block (RBBB) is common and may be caused by ventriculotomy or direct injury to the right bundle itself when suturing the VSD closed on the right ventricular aspect of the interventricular septum. Complete heart block can rarely occur and is associated with late mortality. LV dysfunction may occur after left ventriculotomy to close a muscular VSD. Ventricular arrhythmia can be a late problem.

Schmitt et al caution that use of hypothermic cardiopulmonary bypass in infants and children should be approached with care, as pediatric patients perfused with moderate hypothermia (32ºC) appear to require significantly higher and longer inotropic support compared those perfused with normothermia (36ºC).[25] However, perfusion temperature does not appear to affect cytokine release, organ injury, or coagulation.[25]

Special Concerns in Pregnant Women

Pregnancy and prenatal care

The presence or lack of early care is not a factor in congenital cardiovascular malformations (CCVMs).

VSD associated with pulmonary vascular disease is one of the 2 major maternal cardiac risks; the other is pulmonary edema. A major objective of medical management is to minimize the factors that interfere with the limited circulatory reserve of pregnant women with VSDs. Diuretics can be used judiciously to manage edema of cardiac failure, but they should not be used to treat edema of normal pregnancy.

Pregnant women with heart disease should limit themselves to moderate isotonic exercise. Maternal mortality in pregnant women with heart disease has been associated with the functional class.

Because anxiety is a special concern in a primigravida, the expectant mother should be prepared mentally for pregnancy, labor, delivery, and puerperium.

Labor and delivery

In women with functionally mild unoperated lesions and in patients after successful surgical repair, management of labor and delivery is the same as for pregnant women without a VSD.

The recommendations of the American Heart Association state that no antibiotic prophylaxis is required for a normal vaginal delivery.

For pregnant women with functionally important congenital cardiac disease (unoperated or operated), the management of labor, delivery, and the puerperium is crucial to minimize risk.

Induced vaginal delivery is preferred over cesarean delivery. Cesarean delivery results in twice the blood loss of vaginal delivery. In addition, it is associated with risks of wound infection, uterine infection, thrombophlebitis, and potential postoperative complications.

Activity Restriction

Lifestyle changes (ie, exercise before and after surgery or catheterization) may not be required.

A restrictive VSD with a functional normal heart imposes no exercise limitation. Although patients can safely participate in competitive sports without restriction, adults in this category are uncommon. An important exception is the adult whose moderately restrictive perimembranous VSD decreased in size or closed spontaneously in infancy. However, 2-dimensional (2D) echocardiography with Doppler interrogation and color flow imaging should be performed to determine whether the defect closed by means of formation of a septal aneurysm.

Unrestricted exercise after surgical closure of a moderate-to-large VSD is permitted if the following criteria are met:

  • Acceptable postoperative PA pressure

  • Absence of clinically significant disturbances in ventricular rhythm during maximal exercise stress testing and during 24-hour ambulatory electrocardiography

  • 2D echocardiographic evidence of an intact ventricular septum with normalization of LV and left atrial (LA) size and LV function

  • 12-lead scalar electrocardiogram (ECG) revealing little or no evidence of LV volume overload or right ventricular (RV) pressure overload

Long-Term Monitoring

After intracardiac repair of a VSD, long-term infrequent follow-up is necessary. Patients with small VSDs do not require indefinite follow-up although subacute bacterial endocarditis remains a theoretical risk. 

Patients with perimembranous VSDs who have undergone aneurysmal closure have a high incidence of LV-to-right atrium (RA) shunting and a 6% incidence of subaortic ridge, as shown in a large Chinese study.[6]

With increasing age, the incidence of aortic leaflet prolapse and aortic insufficiency increases in children with the doubly committed and perimembranous type of VSD.

 

Medication

Medication Summary

Medications used in the management of ventricular septal defects (VSDs) associated with evidence of left ventricular volume overload include diuretics, angiotensin-converting enzyme (ACE) inhibitors, and cardiac glycosides.

Diuretics, Loop

Class Summary

Diuretics promote the excretion of water and electrolytes by the kidneys. They are used in the treatment of hypertension; heart failure; and hepatic, renal, or pulmonary disease when salt and water retention has resulted in edema or ascites.

Furosemide (Lasix)

Furosemide increases excretion of water by interfering with the chloride-binding cotransport system, which inhibits sodium and chloride reabsorption in the ascending loop of Henle and the distal renal tubule. Dosing must be individualized. Depending on the response, administer furosemide in increments of 20-40 mg no sooner than 6-8 hours after the previous dose until the desired diuresis occurs. In infants, titrate in increments of 1 mg/kg until a satisfactory effect is achieved.

ACE Inhibitors

Class Summary

ACE inhibitors are used to treat congestive heart failure (CHF). They may be of use to treat systemic afterload.

Captopril

Captopril prevents conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, lowering aldosterone secretion. It can be useful in reducing systemic afterload.

Enalapril (Vasotec)

Enalapril is considered a reasonable first drug of choice in this group because of its increased dosing interval (q12-24h). A competitive ACE inhibitor, it reduces angiotensin II levels, decreasing aldosterone secretion. Enalapril is available in a liquid suspension.

Lisinopril (Prinivil, Zestril)

Lisinopril is considered a reasonable first drug of choice in this group because of its increased dosing interval (q12-24h). It prevents the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, resulting in lower aldosterone secretion.

Inotropic Agents

Class Summary

Cardiac glycosides possess positive inotropic activity, which is mediated by inhibition of sodium-potassium adenosine triphosphatase (ATPase). The also reduce conductivity in the heart, particularly through the atrioventricular (AV) node; therefore, they have a negative chronotropic effect. Cardiac glycosides have similar pharmacologic effects but differ considerably in their speed of onset and duration of action. These agents are used to slow the heart rate in supraventricular arrhythmias, especially atrial fibrillation. They are also administered in chronic heart failure.

Digoxin (Lanoxin)

Digoxin is a cardiac glycoside with direct inotropic effects, in addition to indirect effects on the cardiovascular system. It acts directly on cardiac muscle, increasing myocardial systolic contractions. Its indirect actions increase the activity of the carotid sinus nerve and enhance sympathetic withdrawal for any given increase in mean arterial pressure.