Anil Kumar Singhi1, Kothandam Sivakumar2 1 Senior Consultant, Department of Pediatric Cardiology, Medica Super Specialty Hospital, Kolkata, West Bengal, India 2 Senior Consultant, Department of Pediatric Cardiology, The Madras Medical Mission, Chennai, Tamil Nadu, India
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Correspondence Address: Dr. Anil Kumar Singhi Senior Consultant, Department of Pediatric Cardiology, Medica Super Specialty Hospital, Mukundapur, Kolkata - 700 099, West Bengal India
Source of Support: None, Conflict of Interest: None
Double outlet ventricle is a type of conoventricular anomaly. The great arteries arise predominantly (more than 50%) from one of the ventricle. The aortomitral discontinuity varies from minimum discontinuity to complete bilateral conal tissue. Both right and left ventricles can have double outlet though double outlet right ventricle (DORV) is the most common anomaly in this group of abnormalities. Double outlet left ventricle (DOLV) is relatively rare. There are multiple types of DORV based on the site of ventricular septal defect and great artery relationship and presence or absence of ventricular outflow obstruction. The correct anatomical diagnosis requires a detail segmental approach in echocardiography. The echocardiographic features of DORV reviewed in detail followed by a brief discussion on DOLV.
Keywords: Double outlet left ventricle, double outlet right ventricle, double outlet ventricle
How to cite this article: Singhi AK, Sivakumar K. Double Outlet Ventricle: Echocardiographic Evaluation. J Indian Acad Echocardiogr Cardiovasc Imaging 2020;4:295-303
How to cite this URL: Singhi AK, Sivakumar K. Double Outlet Ventricle: Echocardiographic Evaluation. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2020 [cited 2021 Apr 13];4:295-303. Available from: https://www.jiaecho.org/text.asp?2020/4/3/295/303934
Double outlet ventricle is a spectrum of anomalous ventriculo-arterial connections in which both great arteries arise predominantly (more than 50%) from one ventricle. The infundibular morphology can range from complete muscular conus bilaterally (23%) to minimal semilunar to atrioventricular valve discontinuity. Double outlet right ventricle (DORV) is far more common than double outlet left ventricle (DOLV). This review details the echocardiographic features of DORV in detail followed by a brief discussion on DOLV.
Double Outlet Right Ventricle
DORV is a type of ventriculo-arterial connection where more than 50% of both great arteries arise from the morphological right ventricle. DORV constitutes approximately 1% of all congenital heart disease with a reported incidence of 0.06 cases per 1000 live births. Both sexes are equally affected.,
Clinico-morphological spectrum of double outlet right ventricle
DORV is a type of conotruncal defect in which a variable amount of conal tissue is present under each semilunar valve [Figure 1]. The important determinants that influence the clinical features include (i) anatomical location of ventricular septal defect (VSD) in relation to great arteries, (ii) size of the VSD, (iii) relationship of the great arteries and (iv) presence of outflow obstruction. Traditionally the VSD is present in conoventricular location in the perimembranous region with extension to the trabecular septum.
Figure 1: Echocardiogram in parasternal long axis view showing the conotruncal ventricular septal defect (marked with interrupted arrow) and a large conal tissue (marked with two solid arrows) resulting in aorto-mitral discontinuity. LA (left atrium), LV (left ventricle), RV (right ventricle)
There are multiple classification systems describing DORV. The conventional classification groups the patients based on the location of the VSD and relationship of great arteries [Table 1]. Most VSD in DORV are conotruncal located below either the aortic valve [Figure 2] or below the pulmonary valve [Figure 3] or both. Rarely, they are remote from both great arteries [Figure 4].
Figure 2: Enface three dimensional view of interventricular septum from right ventricular side in subcostal view showing subaortic ventricular septal defect (arrow) and the same is described in an representative cartoon with annotation. Ao (aorta) PA (pulmonary artery), TV (tricuspid valve). L: Left, R: Right, a: artery
Figure 3: Enface three dimensional view of interventricular septum from right ventricular side in subcostal view showing subpulmonic ventricular septal defect. The direction of flow marked with arrow and ventricular septal defect margin with dots. The same is described in a representative cartoon with annotation. Ao (aorta) PA (pulmonary artery), TV (tricuspid valve). L: Left, R: Right, a: artery
Figure 4: Subcostal echocardiogram showing the Left ventricle (LV) to Aorta (Ao) postulated intraventricular pathway in a case of double outlet right ventricle with remote ventricular septal defect in two dimensional (A) and three dimensional view (B). RV (Right ventricle)
Modified Fuwai classification proposed by Pang et al. after analysis of 500 patients with DORV is based on three parameters namely great artery relation, location of the VSD, and presence of outflow obstruction. These parameters determine the clinical features and guide surgery [Table 2].
Table 2: Modified Fuwai classification with double-outlet right ventricle adapted from Pang et al.
The common associations of DORV include pulmonary stenosis in 50% [Figure 5], secundum atrial septal defect in 25% and atrioventricular septal defects in 8%. The other associations were patent ductus arteriosus, right aortic arch, persistent left superior vena cava, and mitral valve anomalies. Coronary anomalies seen in 10% include origin of the left anterior descending coronary artery from the right coronary artery [Figure 6]. These carry significance during transannular patch repair or arterial switch surgeries for various forms of DORV.,
Figure 5: Echocardiogram in parasternal long axis view (a) and with color doppler (b) showing prominent bilateral conus (Subaortic conus marked with red arrow, subpulmonary conus marked with white arrow). Left ventricle (LV) to aorta pathway marked with interrupted arrow. In Colour doppler turbulence in the subpulmonary region is seen. RV (right ventricle). LA: Left atrium
Figure 6: Echocardiogram in parasternal short axis view showing side by side great arteries, Aorta on right and pulmonary artery (PA) on left side. The left anterior descending coronary artery (LAD) seen arising from the right coronary artery (RCA)
Patients with DORV have three different clinical presentations:
Commonest form is “like a Tetralogy of Fallot.” This accounts for 40% of patients. There is a large unrestrictive subaortic VSD and subpulmonary conus is narrowed in its diameter [Figure 5]
Second form presents “like transposition of great arteries,” seen in 20% of patients. The VSD is located in the subpulmonary region [Figure 7]. The larger conal tissue below the aortic valve prevents left ventricular blood to stream into the aorta leading to lower aortic saturation compared to pulmonary artery saturations. This is also named as Taussig Bing anomaly [Figure 3]
The third form is “like a large nonrestrictive VSD.” They present with a large left to right shunt without any pulmonary outflow obstruction and are seen in 15% of patients.
Other less common variants are noncommitted VSD and associations with atrioventricular septal defects with varying degrees of outflow obstructions.,
Figure 7: Echocardiogram in subcostal view of a Taussig-Bing anomaly. The subpulmonary ventricular septal defect marked with interrupted arrow and subpulmonary conus with solid arrow. LV (left ventricle), RV (Right Ventricle). PA: Pulmonary artery, LA: Left atrium
Echocardiogram remains the mainstay in diagnosis of DORV for identifying the location of the VSD, its relation to the great arteries, relationship of great arteries, outflow obstructions, ventricular hypoplasia, atrioventricular valve anomalies, and other associated anomalies. Additional information in patients with suboptimal echocardiogram can be obtained from magnetic resonance imaging, computed tomography, or catheter angiograms. Imaging should provide all information for making a clear surgical plan.
Checklist in double outlet right ventricle
Great artery relationship can be (i) normally related with right and posterior aorta and left and anterior pulmonary artery in patients with situs solitus; (ii) side by side relation – this is the most common form of great artery relationship seen in majority of patients [Figure 6]; (iii) d-malposed aorta – aorta is right and anterior aorta to pulmonary artery and (iv) l-malposed aorta – aorta is to the left to pulmonary artery
Location of the VSD in relation with aortic and pulmonary annulus: The common location of the VSD is (i) subaortic – the two limbs of the septal band fuses completely with subpulmonary conus but fails to fuse below the aorta as the subaortic conus is deficient; [Figure 2] (ii) the next common location is subpulmonary – the two limbs of septal band fuses completely with subaortic conus leaving the subpulmonary area open; [Figure 3] (iii) doubly committed form – where the conal tissues are deficient, the septak band fails to fuse with both the conus leading to a very large defect below both the annuli of the aorta and pulmonary artery and where the subaortic conus is deficient and subpulmonary conus is well developed; (iv) noncommitted form – where the VSD is remote from both great arteries and located entirely in the trabecular or inlet septum [Figure 4]
Size of the VSD. The VSD is nonrestrictive in most of the patients leading to equal pressures in both ventricles. In a small minority of patients, the VSD may be restrictive [Figure 8] compared to the semilunar valve annulus causing suprasystemic left ventricular pressure that gives a gradient between the two ventricles [Figure 9] and [Video 1]
Routability of the VSD towards a semilunar valve: The intervening chordopapillary apparatus of the tricuspid valve in the path between the VSD and the semilunar valve may pose challenges to create an intraventricular tunnel for routing the VSD; other structures that can challenge the routing are accessory straddling mitral valve chordae that gain insertion into the right ventricle or accessory anomalous conal muscle bundles in the right ventricle that protrude into the virtual path of intraventricular tunnel [Figure 4]
Presence of any additional VSD, their location, size and identifying a surgical access to these defects
Relationship of atrioventricular valves to the VSD: The chordal attachments to the edges of the VSD, a potential for atrioventricular valves to obstruct the outflows after constructing a surgical intraventricular tunnel, override and straddling of the valves, anomalies of the valves including clefts or prolapse, annular hypoplasia, severity of regurgitation (if present) should be recorded
Ventricular outflow tract obstruction should be described at subvalvar, valvar, and supravalvar levels; nature of the pulmonary valve and its annular dimensions should be recorded [Figure 5]
Branch pulmonary artery sizes at mediastinal and hilar regions, their Z-scores, stenosis at ductal insertion site should be noted
Additional anomalies of surgical relevance include atrial septal defect, atrioventricular septal defects and patent arterial ductus, sidedness of aortic arch, and dimensions of aortic arch
Coronary artery anomalies seen in 10% of patients may carry relevance when they need surgery-creation of transannular patch in “tetralogy type of DORV” is difficult if the right coronary artery arises from left coronary and crossed the right ventricular outflow [Figure 10] and coronary transfer before arterial switch in “transposition type of DORV”
Ventricular hypoplasia may impair biventricular repairs [Figure 11].
Figure 8: Enface three dimensional view of interventricular septum from right ventricular side in subcostal view showing restrictive ventricular septal defect (marked with interrupted arrow). The Subpulmonary conus marked with a solid arrow. PA (pulmonary artery), TV (tricuspid valve) RV (Right Ventricle)
Figure 9: Echocardiogram (a) in the parasternal long axis view showing subaortic Ventricular septal defect (VSD) with 90% aortic override. Large subaortic conus causing significant aortomitral discontinuity (marked with bold arrow). The VSD is restrictive (marked with interrupted arrow) (b, d) Turbulent color flow seen across the VSD which is truly restrictive (c) The restrictive VSD well delineated in subcostal long axis echocardiographic view. LA (left atrium), LV (Left ventricle) RV (Right Ventricle). PA (pulmonary artery). (Movie 1)
Figure 10: Echocardiogram with color doppler in parasternal short axis view (A, B) showing right coronary artery (RCA, marked with white arrow) arises from left coronary artery (LCA, marked with red arrow) and crossed the right ventricular outflow tract. PA (pulmonary artery)
Some illustrative case scenarios of double outlet right ventricle with echocardiographic delineation in various imaging planes discussed.
Patient #1: A patient with double outlet right ventricle with normally related great artery and subaortic VSD and the varied level of aortic override. In the first patient, VSD has 50% aortic override [Figure 12] and [Video 2].
Patient #2: The patient with 200% DORV. He has both the great arteries completely (100%) committed to the right ventricle without any outflow tract obstruction. A long intraventricular tunneling repair to route the left ventricle to aorta was successful [Figure 13] and [Video 3]
Patient #3 and 4: Cases of Taussig Bing anomaly. DORV with malposition of great arteries and subpulmonary VSD present as “Transposition” physiology. #3 [Figure 14] and [Video 4] and patient #4 [Figure 15] and [Video 5].
Patient #5: A case with DORV and nonroutable VSD. The tricuspid valve tissue came on the way of systemic outflow which made the VSD non repairable as the straddled tricuspid valve chordae attached to the left ventricle [Figure 16] and [Video 6]
Patient #6: DORV with remotely placed trabecular VSD. It may have a pathway to systemic outflow as seen in patient 7 which has significant surgical implication [Figure 17] and [Video 7].
Patient #7: DORV with difficulty to route VSD requiring a long intraventricular tunnel. The dynamic two-dimensional and three-dimensional echocardiographic assessment helped to ascertain routability and the patient underwent successful DORV repair by intraventricular tunneling with a long patch. Postoperative echocardiogram showed unobstructed left ventricle to systemic outflow and no residual VSD flow [Figure 18] and [Video 8].
Figure 12: Echocardiogram (a) in a parasternal long axis view showing subaortic Ventricular septal defect with 50% aortic override. Aortomitral discontinuity marked with arrow. (b) The pulmonary artery (PA) completely committed to the right ventricle (RV). (c) In Subcostal short axis aorta (AO) seems to be ˜50% committed to RV. (d) The Pulmonary artery in short axis completely committed to RV. (Movie 2). LV: Left ventricle
Figure 13: Echocardiogram (a) subcostal short axis view and (b) parasternal long axis view showing aorta (AO) fully committed to (RV), The Ventricular septal defect (*) is the only exit from the left ventricle (LV). (c) Parasternal long axis view with anterior sweep showing pulmonary artery (PA) arising from RV. (d) Parasternal short axis view showing side by side arrangement of great artery with Aorta (AO) toright and pulmonary artery (PA) to left. Post operative echocardiogram after intraventricular tunnel repair in modified apical view showing long LV to Aorta (AO) tunnel with long intraventricular patch (arrow), in color doppler (f) good laminar flow seen in LV to Aorta (AO) pathway. (Movie 3). LV: Left ventricle, RV: Right ventricle
Figure 14: Echocardiogram (a) in apical view showing pulmonary artery (PA) committed >50% to the right ventricle (RV) in Taussig Bing anomaly. (b) In Subcostal short axis view aorta (AO) seen fully committed to right ventricle and away from ventricular septal (VSD).(c) in the parasternal long axis view showing subpulmonic Ventricular septal defect (VSD) with >50% override. Pulmonary mitral discontinuity marked with arrow. (d) Color flow seen across the pulmonary outflow which is mildly turbulent in subcostal short axis view. (e) Three-dimensional echocardiogram in the subcostal short axis showing the subpulmonic VSD marked with a small arrow and distal aorta arising from the right ventricle. (f) in Enface view of interventricular septum from subcostal view the subpulmonic VSD enface seen. (arrow) (Movie 4). LV: Left ventricle
Figure 15: Echocardiogram in subcostal short axis view (a) showing Pulmonary artery (PA) committed >90 to right ventricle (RV) (b) Aorta (Ao) seen completely committed to RV. A prominent subaortic conus seen as well as a pathway from left ventricle (LV) to Aorta. (c) Enface view of interventricular septum from subcostal view showing anterior aorta (aorta) The Ventricular septal defect marked with red arrow. (d) Parasternal short axis view showing L malpositioned aorta (AO). (e) The right coronary artery(RCA) seen coming from the right facing sinus. (f) Enface Three dimensional echocardiogram from subcostal view showing the subpulmonary VSD (white arrow). (Movie 5)
Figure 16: Echocardiogram in subcostal view (a) showing remote trabecular Ventricular septal defect (VSD). Though Aorta (Ao) is seen away from VSD (b) a clear long intraventricular tunnel pathway visible from Left ventricle (LV) to Aorta. The muscular VSD in the inlet region away from aorta is marked with an arrow in three dimensional enface image in subcostal view (c). (Movie 7). PA: Pulmonary artery, RV: Right ventricle
Figure 17: Echocardiogram in subcostal view (a) showing remote trabecular VSD. Though aorta (Ao) is seen away from VSD (b) a clear long intraventricular tunnel pathway visible from left ventricle to aorta. The muscular VSD in the inlet region away from aorta is marked with an arrow in three-dimensional enface image in subcostal view (c). VSD: Ventricular septal defect. LV: Left ventricle, RV: Right ventricle
Figure 18: (a) Parasternal view of double outlet right ventricle (RV) with tricuspid valve (TV) and aorta (Ao). (b) Subxiphoid short axis view showing aorta (Ao) arising from RV. (c) Pulmonary artery (PA) seen away from ventricular septal defect on leftward sweep, VSD separated by conal septum. (d) On a parasternal long axis view we see PA, howsever VSD not well seen. (e) Parasternal short axis view, normally related great arteries seen, Pulmonary artery to left and aorta to right. (f) Subxiphoid coronal sweeps both the great arteries seen arising from the right ventricle (RV), they are normally related. (f) Three dimensional en face reconstruction in sub xiphoid view showing the en face subaortic ventricular septal defect which is away from aortic annulus by a subaortic conus. The dotted line showing an imaginary patch for future intraventricular tunnel closure of VSD. (Movie 8)
Surgery for DORV depends on the anatomy, physiology, age of the patient. If the VSD is conotruncal, repair is often possible by routing the VSD into the nearest semilunar valve annulus. In remote defects, routability is difficult and hence palliative surgeries like pulmonary artery banding or aortopulmonary shunts are preferred. The physiology also dictates the time of surgery. In “Fallot like presentation,” total correction is often feasible with a transannular patch or use of conduit from right ventricle to pulmonary artery. In Taussig Bing anomaly, arterial switch surgery is performed early to avoid pulmonary vascular disease.
In the case of DORV with remote VSD, a detailed analysis is required for possible complex routing of VSD with intraventricular tunnel which may be possible in some of these cases [Figure 7]. Completely nonroutable VSD are planned for staged univentricular palliation. Intraoperative transesophageal echocardiogram is useful to identify residual VSD, residual outflow obstructions and additional VSD missed earlier. Echocardiogram remains to be the basic tool in evaluation for double outlet right ventricle.
Double Outlet Left Ventricle
DOLV is rare compared to double outlet right ventricle. Presence of VSD, its size and relationship of VSD to great arteries, presence of outflow tract obstruction determine the clinical presentation and hemodynamic status.
The VSD is subaortic in the majority cases of DOLV (73%) and subpulmonary in the rest. The great artery relationship is often abnormal and can be d or l malposed or side by side. 90% of patients have valvular or subvalvular pulmonary stenosis. Depending on the location of VSD, they can present with “tetralogy physiology” or “transposition physiology.”
In an example of case (patient #8), DOLV with subaortic VSD and a transposition like physiology described. The patient finally underwent arterial switch operation and VSD routing to systemic outflow [Figure 19] and [Video 9].
Figure 19: (a) Subxiphoid short axis view showing large subaortic overriding VSD and confirms aortomitral fibrous continuity (b). Color flows from right ventricular blood to aorta (c) origin of pulmonary artery exclusively from the left ventricle (d) and left ventricular blood going to the pulmonary artery. Long axis view (e) show aorta (Ao) and pulmonary artery (PA) arising from the left ventricle (LV); Blood from right ventricle (RV) streams into the aorta on color doppler imaging (f) creating a transposition physiology. (g) Parasternal long axis view showing aorto mitral fibrous continuity, absence of subaortic conus and large subaortic overriding VSD (h); On a leftward sweep, pulmonary mitral fibrous continuity seen though VSD not visualised. The subpulmonary conus is not seen. (Movie 9)
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