Ventricular Septal defects Echocardiography

By Sruthi Meenaxshi

1. Ventricular septal defects Dr.S.R.Sruthi Meenaxshi,MBBS,MD,PDF

2. ANATOMIC TYPES The ventricular septum is a nonplanar, three-dimensional partition of the ventricle with five components: the membranous, muscular (also known as trabecular), infundibular, inlet atrioventricular (AV) segments VSDs result from deficient growth or failure of fusion of these components and vary in size from tiny apertures to very large defects with virtual absence of the septum

3. In 2000, the Society for Thoracic Surgery (STS) and the European Association for Cardiothoracic Surgery (EACTS) established a unified reporting system for congenital heart disease, including VSD . They classified VSD into four types: Type 1 defects involve the infundibular septum, Type 2 defects involve the membranous septum, Type 3 defects involve the inlet septum, and Type 4 defects involve the muscular septum.

4. Types of vsd

5. Ventricular septal defects

6. INFUNDIBULAR VSD Infundibular VSD (type 1, also referred to as supracristal , subarterial , subpulmonary , conal , or doubly-committed juxta-arterial VSD ) results from deficiency in the septum above and anterior to the crista supraventricularis , beneath the aortic and pulmonary valves The resultant loss of support of the right and/or left aortic valve cusp causes cusp prolapse into the VSD, leading to aortic regurgitation that could be progressive and occasionally aortic sinus dilation Infundibular VSDs are common in individuals of Asian descent, accounting for one-third of VSDs.

7. MEMBRANOUS VSD A membranous VSD (type 2, also known as perimembranous or conoventricular ) results from deficiency of the membranous septum and is the most common type of VSD in adults (80 percent of VSDs ) This defect is inferior to the crista supraventricularis and borders the septal leaflet of the tricuspid valve. The defect may extend into the muscular septum and is then referred to as a perimembranous (or paramembranous ) VSD.

8. INLET VSD Inlet VSD (type 3, also known as AV canal type ) results from deficiency of the inlet septum, located beneath both mitral and tricuspid valves Despite proximity to those valves, this type of defect is not associated with mitral or tricuspid regurgitation unless associated with atrioventricular septal defect; these defects are typically large and often associated with Down syndrome. 

9. APICAL 4 CHAMBER – INLET VSD

10. GERBODE DEFECT OR AV VSD A Gerbode defect or AV VSD is the least common VSD , caused by deficiency of the membranous septum separating the left ventricle (LV) from the right atrium, resulting in an LV-to-right atrial shunt. This defect has also been reported as an acquired lesion ( eg , following endocarditis and valve replacement

11. MUSCULAR VSD Muscular VSDs (type 4), which account for 5 to 20 percent of VSDs in adults, are bordered only by muscle within the trabecular septum, away from the cardiac valves. Muscular defects can be small or large, single or multiple, and occasionally oblique with multiple exits resembling Swiss cheese.

12. Small restrictive VSDs are associated with small left-to-right shunts (pulmonary to systemic flow ratio [ Qp:Qs ] <1.5:1), and the pulmonary vascular resistance is not significantly elevated. The orifice dimension is ≤25 percent of the aortic annulus diameter. There is no LV volume overload or pulmonary hypertension (PH).

13. Most small isolated muscular and perimembranous VSDs close spontaneously during childhood. Adults with an isolated small restrictive VSD with small left-to-right shunt (often referred to as " maladie de Roger" ) generally remain asymptomatic and present with a systolic murmur, often with a palpable thrill from the VSD. There is risk of endocarditis associated with this lesion, but the magnitude of risk is low. In a minority of cases, a diastolic murmur from aortic regurgitation develops

14. Moderately restrictive defects that have not completely closed are associated with moderate shunts ( Qp:Qs ≥1.5:1 and <2:1). The defect typically measures >25 but <75 percent of the aortic annulus diameter and results in mild to moderate volume overload of the pulmonary arteries, left atrium, and LV. Patients with this type of lesion often have mild to moderate pulmonary arterial hypertension.

15. Children with moderate-sized VSDs may remain asymptomatic or develop symptoms of mild HF in childhood. HF usually resolves with medical therapy and with time as the child grows and the VSD gets smaller in absolute and/or relative terms. However, some adults have moderately restrictive defects that have not been completely closed, and these patients may develop PH and may have associated symptoms related to the LV volume overload or PH.

16. Large nonrestrictive VSDs (defined as those with diameters ≥75 percent of that of the aortic annulus) lead to the following clinical scenarios

17. Early large left-to-right shunt – Most infants with large VSDs have early large left-to-right shunts ( Qp:Qs ≥2.1) as the pulmonary vascular resistance falls postnatally. This results in LV volume overload and HF. These VSDs are generally closed during the first year of life. •Progressive pulmonary arterial hypertension – If a large VSD remains uncorrected, it can cause progressive PH due to longstanding unobstructed pulmonary flow with resultant pulmonary arterial obstructive disease. The volume of the left-to-right shunt will decline as pulmonary vascular resistance rises

18. Spectrum of clinical presentation    The spectrum of isolated residual VSDs in adults includes the following clinical and hemodynamic types The direction and severity of the shunt associated with VSD are determined by the VSD's functional size and, in the absence of right ventricular (RV) outflow obstruction, by the ratio of pulmonary to systemic vascular resistance or ventricular afterload.

19. A small isolated VSD with left-to-right shunt is considered a simple congenital heart defect, whereas a VSD associated with one or more additional abnormalities and/or moderate or greater shunt is considered to be of moderate complexity. VSD associated with Eisenmenger syndrome is a complex congenital heart defect given the associated cyanosis, pulmonary hypertension, and multisystem involvement

20. A ventricular septal defect (VSD) is one of the most common congenital cardiac abnormalities in the newborn, but it is less common in the adult due to spontaneous closure of most muscular VSDs during childhood. It can occur as an isolated finding or in combination with other congenital defects. VSD can also be an acquired disorder, occurring after acute myocardial infarction or chest wall trauma The echocardiographic evaluation of VSD will be reviewed here

21. EISENMENGER SYNDROME Development of right-to-left shunt (Eisenmenger complex) – With progressive increases in pulmonary vascular resistance (and/or failure of pulmonary vascular resistance to fall normally postnatally), the RV pressure may reach systemic or suprasystemic levels, leading to reversal of the shunt so that it is directed right-to-left with resultant hypoxemia and cyanosis; this is known as Eisenmenger syndrome Eisenmenger syndrome in association with VSD is known as Eisenmenger complex ; this typically presents during late childhood to early adulthood. Elevated RV and right atrial pressures cause RV hypertrophy and right atrial enlargement. 

22. ECHOCARDIOGRAPHIC EVALUATION Echocardiography is valuable not only in diagnosing VSDs but also in the percutaneous and surgical treatment of these defects . Echocardiographic evaluation of VSDs includes: ●Identification of the location of defects on the septum ●Establishing the number of defects ●Delineation of associated anatomic features ●Assessment of the size and hemodynamic significance of the defects ●Guidance of interventional and surgical treatment

23. The septum is a complex curved surface; traditionally careful assessment using multiple two-dimensional (2D) echocardiographic planes has been used to define the location and extension of defects. Defects are generally described as membranous, muscular, supracristal , and inlet, a single VSD may not be confined to any one region of the septum but may extend into multiple adjacent regions Additionally, multiple defects in one or more regions of the septum may also be present.

24. Color flow Doppler is a very useful adjunctive method to search and screen for VSDs. This modality can be used to help localize and confirm the presence of VSDs by their characteristic flow patterns.

25. Three-dimensional (3D) echocardiography can also be used to define the anatomy of VSDs . 3D echocardiography allows localization of the defect and defining its relationship to other cardiac structures, and is superior to 2D imaging in delineating the shape and size of the VSD(s) This information is particularly important in choosing candidates and selecting devices for catheter based closure of defects, and in the management of muscular VSDs in particular 

26. Given the increasing availability of real-time 3D echocardiography and the expanding field of interventional and hybrid procedures for treatment of VSDs , echocardiography has an essential role in both the catheterization and surgical suites. Both two-dimensional and 3D echocardiography can be performed either from a transthoracic or transesophageal approach, though transesophageal imaging is often preferred in procedural management of VSDs.

27. Membranous VSD    Defects in the membranous septum are located at the intersection of the trabecular , inlet, and outlet regions of the septum, situated just apical to the aortic valve and beneath the septal leaflet of the tricuspid valve. In the parasternal long axis echocardiographic view, these defects are seen just below the aortic valve In the orthogonal short axis views of the left ventricular outflow tract, perimembranous defects can be seen beneath the septal leaflet of the tricuspid valve 

28. Membranous defects can also be seen beneath the aortic valve in apical imaging planes by angling the transthoracic transducer anteriorly toward the aortic outflow tract. In smaller patients with good subcostal imaging windows, the boundaries of these defects are imaged well in the coronal and sagittal views of the membranous septum.

29. Membranous defects may close spontaneously, either partially or completely, due to apposition of the septal leaflet of the tricuspid valve . In some cases, septal apposition results in an " aneurysm of the ventricular septum ," which is best seen in the parasternal long and short axis views but can be appreciated from multiple windows Color flow Doppler mapping is useful for establishing the presence of residual shunt flow through the "aneurysm.“ Aneurysm formation most frequently begins in early infancy and may be associated with a decrease in size or spontaneous closure of even relatively large defects

30. A number of associated findings may be seen with membranous VSDs, including: ●Double chambered right ventricle, which refers to hypertrophy of the muscle bundles between the inlet and outlet portions of the right ventricle, resulting in mid chamber obstruction These muscle bundles are particularly well seen in subcostal coronal and sagittal images, but may also be seen in parasternal short axis imaging in larger patients.

31. left ventricular to right atrial shunt (via Gerbode defect), which may be demonstrated by two dimensional imaging, but is usually first suggested by color flow mapping demonstrating a high velocity jet originating in the crux of the heart in parasternal short axis, apical four chamber, or subcostal coronal images

32. LV- RA SHUNT GERBODE DEFECT

33. A subaortic ridge and associated subaortic stenosis, which is an uncommon finding Nevertheless, the left ventricular outflow tract should be carefully evaluated in parasternal long axis and apical images to rule out this abnormality

34. Muscular defects   Defects in the muscular septum are often multiple, especially if they are a complication of a myocardial infarction, and may be associated with defects in other regions of the septum. Color flow Doppler mapping is invaluable for detecting smaller defects that may be difficult to identify within the trabeculations of the right ventricle when only 2D transthoracic imaging is used; defects in the apical septum are the most likely to be missed

35. Muscular vsd

36. Color flow Doppler mapping is very helpful for identifying muscular defects, even at suboptimal angles of interrogation. However, in patients with increased right ventricular pressure, the color flow patterns for the flow velocity across these and all other types of VSDs become less apparent, decreasing the sensitivity of Doppler for their detection

37. Supracristal defects   Supracristal defects, sometimes referred to as subpulmonic or subpulmonary defects, are located caudal to the pulmonary valve and cephalad to the crista supraventricularis . Although they may be difficult to distinguish from membranous defects in the parasternal long axis view of 2D transthoracic echocardiography, they are often easily identified beneath the pulmonary valve in the parasternal short axis images obtained at the level of the arterial roots In younger patients , the relationship between the defect and the pulmonic valve can also be seen in the subcostal sagittal view

38. Prolapse of the unsupported right coronary cusp of the aortic valve into the defect may occur with supracristal VSDs and occasionally with perimembranous defects Associated prolapse of the noncoronary cusp occurs less commonly, may be associated with more significant aortic insufficiency and may be associated with a higher risk of failure of surgical repair Prolapse of the leaflet into the defect is best observed in parasternal and subcostal long axis, and apical views When transthoracic findings are equivocal, TEE can be particularly helpful in diagnosing prolapse. Aortic valve regurgitation may occur with leaflet prolapse due to the progressive distortion of the leaflet; this distortion may be seen in parasternal short axis views of the aortic valve leaflets. The right coronary cusp deformation index and right coronary cusp imbalance indices may be used to quantify the degree of deformation. These indices correlate with the severity of aortic valve regurgitation and may be used in decisions regarding surgical intervention

39. Vsd with prolapsed rcc of aortic valve

40. Inlet defects   — Inlet defects occur at the crux of the heart, posterior and inferior to membranous and outlet defects, and at the junction of the atrioventricular valves. Similar to other VSDs, inlet defects may be seen in many transthoracic echocardiographic imaging planes; however, these defects and their characteristic relationship to the atrioventricular valves are best demonstrated in apical and subcostal coronal views The location of these defects in the posterior septum can be well seen in the parasternal short axis view.

41. Inlet vsd

42. Assess atrioventricular valves in inlet vsd The relationship of the atrioventricular valves to the VSD must be carefully assessed. Tricuspid valve chordal attachments commonly insert on the crest or right ventricular surface of the septum. Anomalous chordal attachments of the mitral valve may also insert on the septum. In addition, either atrioventricular valve may straddle the defect, with chordal attachments crossing the defect and attaching anomalously on the septum or free wall of the opposite ventricle, complicating approaches to repair of the defect. It is important to assure that two atrioventricular valves are present, since these inlet VSDs may be part of a larger endocardial cushion defect.

43. Malalignment defects   Assessment of the relationship between the components of the ventricular septum and the atrial and ventricular septa must be included in the evaluation of a VSD. Malalignment defects occur when there is an abnormal relationship between the atrial and ventricular septa or between the individual components of the ventricular septa Overriding and straddling atrioventricular valves are seen when there is malalignment of the atrial and ventricular septa. Malalignment of the conal septum , which partitions the great arteries and the trabecular septum dividing the ventricular chambers, may result in subaortic obstruction when there is posterior deviation of the conal septum. Aortic override with or without subpulmonary stenosis occurs when there is anterior deviation of the conal septum

44. malalignment of conal septum resulting overriding of aorta and subpulmonic stenosis – tetralogy of fallot

45. HEMODYNAMIC ASSESSMENT The degree of shunting through a defect is influenced by the size of the defect and by the balance of resistances in the pulmonary and systemic circulations . The pressure and volume loads imposed by large VSDs result in elevations in pulmonary arterial pressure and resistance. Calculations of the ratio of pulmonary to systemic blood flow ( Qp /Qs) have less clinical utility than measurements of right ventricular and pulmonary arterial pressures, which reflect the effect of the VSD on the pulmonary vascular bed.

46. Shunt determination   — Two- and three-dimensional (3D) imaging can give important qualitative information about the degree of shunting associated with the VSD. Both left atrial and left ventricular cavity dilation are present in VSDs that produce significant left-to-right shunting. Flow-related increases in transpulmonary and transmitral velocities, assessed by Doppler, may be documented in such lesions, while pulsed Doppler and Doppler color flow mapping can delineate the timing and direction of shunting during the cardiac cycle .

47. in most individuals, left-to-right shunting predominates in mid and late diastole and throughout systole, while right-to-left shunting, which may not be clinically significant, is commonly seen in early diastole. However, with evolving pulmonary hypertension and pulmonary vascular disease, right-to-left shunting may occur in early and mid-diastole, and even in late systole

48. The magnitude of left-to-right shunting at a VSD can be estimated using any of several methods. ●Traditionally, the ratio of pulmonary to systemic blood flow ( Qp /Qs) has been estimated using volumetric flow data, relying on measurements of aortic and pulmonary or mitral velocity or velocity time integrals, and corresponding luminal diameters or cross-sectional areas

49. Potential sources of error in this measurement include the limitations of lateral resolution in measurement of vessels and valve orifices, changes in the size of these structures during the cardiac cycle, suboptimal angle of Doppler interrogation, and the presence of turbulence in the pulmonary artery obscuring the Doppler outflow signal

50. Estimates of Qp /Qs using color Doppler and flow convergence and of volumetric flow at the VSD have been shown to correlate with the measured Qp /Qs in the cardiac catheterization laboratory. 3D echocardiographic measurements of the color Doppler imaged vena contracta and estimates of shunt flow ratio have also been shown to correlate with cardiac catheterization data

51. estimation of left ventricular end diastolic pressures   — Tissue Doppler indices, known to correlate with left ventricular end-diastolic pressure (LVEDP) in adults, have also been shown to reflect LVEDP in the setting of VSDs in children. In a study of children undergoing concurrent cardiac catheterization, an E/Ea ratio greater than 9.8 was consistent with an LVEDP greater than 10 mmHg

52. Pressure gradient across the membranous vsd

53. The common findings of tricuspid and pulmonary regurgitation often allow estimation of right ventricular and pulmonary arterial pressures. Right ventricular systolic pressure can be estimated using the sum of the estimated right atrial pressure and the gradient between the right atrium and right ventricle as derived from the modified Bernoulli equation applied to the peak velocity of tricuspid regurgitation

54. Estimation of right ventricular systolic pressure

55. Mean and end diastolic pulmonary arterial pressures can be derived from analysis of the peak and end diastolic velocities of the pulmonary regurgitation jet, respectively In the assessment of VSDs, these measurements of right ventricular and pulmonary artery pressures give crucial information regarding patient hemodynamics.

56. Membranous vsd

57. Ventricular septal defect