|FOCUS ISSUE - CONGENITAL HEART DISEASE
|Year : 2020 | Volume
| Issue : 3 | Page : 370-377
Complex Congenital Heart Disease: Echocardiographic Evaluation
Srinivas Lakshmivenkateshiah1, Ashutosh Singh2, Nilesh Bachhav1
1 Department of Pediatric Cardiology, Jupiter Hospital, Thane, Maharashtra, India
2 Department of Pediatric Cardiac Surgery, Jupiter Hospital, Thane, Maharashtra, India
|Date of Submission||01-Oct-2020|
|Date of Acceptance||04-Oct-2020|
|Date of Web Publication||18-Dec-2020|
Dr. Srinivas Lakshmivenkateshiah
1405, Vithika A Wing, Dost Vihar Residency, Vartak Nagar, Thane West - 400 606, Maharashtra
Source of Support: None, Conflict of Interest: None
Various combinations of congenital heart defects are included in complex congenital heart disease. Various pathologies of cardiac structures have varied embryological dysmorphology. Lesions described are single ventricle pathologies, hypoplastic left heart syndrome, tricuspid atresia, pulmonary atresia and intact ventricular septum, and crisscross atrioventricular connections. Irrespective of underlying structural abnormalities, most of these lesions will need a unified single ventricle pathway of palliative surgeries for continued survival. A few complex lesions are amenable to corrective surgery. Approach to diagnosis, echocardiography of different lesions, a unified approach toward treatment is discussed.
Keywords: Complex congenital heart disease, echocardiography, hypoplastic left heart syndrome, palliative surgery, pulmonary atresia, single ventricle, tricuspid atresia
|How to cite this article:|
Lakshmivenkateshiah S, Singh A, Bachhav N. Complex Congenital Heart Disease: Echocardiographic Evaluation. J Indian Acad Echocardiogr Cardiovasc Imaging 2020;4:370-7
|How to cite this URL:|
Lakshmivenkateshiah S, Singh A, Bachhav N. Complex Congenital Heart Disease: Echocardiographic Evaluation. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2020 [cited 2021 Apr 13];4:370-7. Available from: https://www.jiaecho.org/text.asp?2020/4/3/370/303950
| Introduction|| |
While there is no universal definition for complex congenital heart defects (CCHDs), these groups of defects include all complex lesions of the heart with more than one cardiac structural abnormality which cannot be repaired with standard surgical procedures. In this chapter, we shall lay emphasis on the various complex lesions where anatomic repair with two functional ventricle circulation is often not possible. Apart from the anatomic details of intracardiac structures, following factors need to be considered before we assign the diagnosis and plan treatment. They include but not limited to the description of segmental analysis, viscero-atrial situs arrangement, pulmonary and systemic venous anomalies, status of pulmonary vascular resistance, and extracardiac abnormalities. We shall describe following CCHDs.
- Abnormal atrio-ventricular (AV) connection
- Univentricular AV connection
- Criss-cross AV connections
- Straddling and over-riding of AV valves.
- Anatomic single ventricle due to absent interventricular septum
- Discordant AV or ventriculo-arterial (VA) connections with hypoplastic ventricles
- Out flow tract abnormalities.
- Extremely hypoplastic/atretic aortic or pulmonary valves
- Double outlet ventricles.
Lesions such as total anomalous pulmonary venous connection, transposition of great arteries, corrected transposition of great arteries, truncus arteriosus, aorto-pulmonary window, atrio ventricular septal defects (AVSDs), Ebstein's anomaly, and double-outlet right ventricle (RV) are addressed elsewhere separately.
| Univentricular Atrio-Ventricular Connections|| |
Terminology of univentricular AV connections is as described by Anderson et al. It essentially means both atria are connected to one ventricle. Three basic variants are as follows:
- Double-inlet ventricle – both atria connected to one ventricle through two AV valves
- Single-inlet ventricle – tricuspid/mitral atresia
- Common inlet ventricles – example unbalanced AVSD (will be addressed in AVSD chapter).
| Double inlet ventricles|| |
Double-inlet left ventricle (DILV) is more common than double-inlet RV [Figure 1]. This is the most common form of single ventricle (78%) three sub types are described.
|Figure 1: Double-inlet left ventricle. Both atria connected to the left ventricle apical four chamber view: RA: Right atrium, LA: Left atrium, MV: Mitral valve, TV: Tricuspid valve, RV: Right ventricle|
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- DILV with normally related great arteries - Holmes heart (15%) [Figure 2]
- DILV with d-malposed great arteries (25%) [Figure 3]
- DILV with l-malposed great arteries (38%) [Figure 4].
|Figure 2: Double inlet left ventricle with normally related great arteries. (a) apical four chamber view demonstrates tricuspid valve (TV) committed to left ventricle (LV). (b) Demonstrates left atrium (LA) committed to left ventricle (LV) via. Mitral valve (MV). Ao: Aortic valve. VSD: Ventricular septal defect, RA: Right atrium|
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|Figure 3: (a) Subcostal view: Double-inlet left ventricle with d-malposed great arteries. (b) Parasternal long-axis view shows small RV and d-malposed Aorta. LA: Left atrium, RV: Right ventricle, LV: Left ventricle. PA: pulmonary artery, Ao: Aorta, PV: Pulmonary valve, AoV: Aortic valve|
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|Figure 4: DILV with l-malposed great arteries. Hypoplastic right ventricle (RV) forms the left heart shoulder from which the ascending aorta originates. Arrow shows right coronary artery. LA: Left atrium, DILV: Double inlet left ventricle|
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The most common form of univentricular AV connection is a DILV with a hypoplastic RV. In this anomaly, the rudimentary RV is located anterior and superior to the dominant LV chamber. Most commonly the dominant LV is connected to the pulmonary trunk and the rudimentary RV, to the aorta (discordant VA connections). If the hypoplastic RV lies along the right shoulder of the heart, the sidedness of the dominant LV will be normal, and if it is found on the left shoulder of the heart, then the left ventricular sidedness will be the mirror image (l-loop ventricles). In the dominant chamber, direct continuity between one or both AV valves and the semilunar valve establishes its morphology as left ventricular. In short axis, the plane of the ventricular septum will be angled rather than perpendicular to the diaphragmatic ventricular wall and it will be displaced superiorly. Associated abnormalities include straddling and over-riding of AV valves, hypoplasia of either ventricle, outflow tract obstruction, pulmonary trunk or aortic arch hypoplasia, VA discordance, and abnormalities of systemic and pulmonary veins.
Surgical management of inflow abnormalities and anatomical single ventricles: Double-inlet ventricles usually need surgery in early infancy. Only the ones with atrial situs solitus, DILV, with no systemic outflow obstruction, and moderate pulmonary outflow obstruction can survive postinfancy without surgical repair. Most of the surgical procedures for this subset of patients are palliative in nature.
| Single Inlet Ventricle|| |
One of the AV valves is either atretic or hypoplastic with varying degrees of hypoplasia of ipsilateral ventricles and outflow tracts. Two important lesions are described: Tricuspid atresia and its variants and mitral atresia with spectrum of hypoplastic left heart syndrome (HLHS).
Tricuspid valve atresia is one of the more common forms of cyanotic congenital heart disease and constitutes 2.7% of all congenital heart disease. There is the absence of connection between the right atrium and ventricle. The atretic valve is usually muscular or occasionally membranous [Figure 5]. Atrial septal defect (ASD) and ventricular septal defect (VSD) are obligatory shunts. RV is hypoplastic in most common variant. Occasional associated lesions are bilateral superior vena cavae, juxta posed right atrial appendage, presence of pulmonary outflow obstruction in form of infundibular stenosis or restrictive VSD results in CCHD with reduced pulmonary blood flow. Tricuspid atresia is classified on the basis of size of VSD, VA connection, and presence or absence of RV outflow obstruction [Table 1]. Surgical repair of tricuspid atresia is a prototype of staged single ventricle repair.
|Figure 5: Tricuspid atresia. Apical four-chamber view. RA: Right atrium, LA: Left atrium, LV: Left ventricle, VSD: Ventricular septal defect, RV: Right ventricle, Arrow indicated atretic tricuspid valve, MV: Mitral valve|
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Mitral atresia and hypoplastic left heart syndrome complex
HLHS includes several combinations of left heart abnormalities associated with a degree of LV hypoplasia that is not suitable for two ventricle repair [Figure 6]. The combinations may include.
|Figure 6: Mitral atresia. Apical four-chamber view. RA: Right atrium, LA: Left atrium, TV: Tricuspid valve, LV: Hypoplastic left ventricle, Arrow: Multiple VSDs. MV: Atretic mitral valve, RV: Right ventricle|
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- Mitral atresia with aortic atresia
- Patent mitral valve with aortic atresia
- Patent mitral valve with severe aortic stenosis
- Variants including severe LV hypoplasia and VSD and Unbalanced AVSD with LV hypoplasia.
Aortic atresia is associated with extremely hypoplastic ascending aorta that acts as a conduit to coronaries [Figure 7]a. Varying degrees of aortic arch hypoplasia and coarctation of aorta are often noted [Figure 7]b. Compensatory enlargement of right heart structures is often noted. ASD is usually patent and wide open, restrictive ASDs are associated with poor prognosis due to the abnormal development of pulmonary vasculature.
|Figure 7: (a) Hypoplastic ascending aorta (Ao) and pulmonary artery (PA). Parasternal long-axis view. (b) Aortic arch hypoplasia. AA: Ascending aorta, MP: Main pulmonary artery, Arrow: Transverse arch|
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| Surgical Options|| |
These babies are born with duct-dependent systemic circulation and need a palliative Norwood type of operation for the survival in the neonatal period. Alternatives to urgent Norwood operation are a) hybrid Norwood procedure (bilateral branch pulmonary artery bands with a duct stent to maintain distal perfusion with or without a reverse Blalock Taussing [BT] shunt) or b) bridge to Norwood procedure (bilateral branch pulmonary artery bands with the duct kept open with prostaglandin). Norwood is a palliative operation with a high degree of technical complexity and poor outcomes in inexperienced hands. Stage 2 palliation following Norwood involves a bidirectional cavopulmonary shunt or Hemi-Fontan operation followed by completion Fontan. Corrective surgeries for HLHS have been undertaken in borderline hypoplasia (z >−3) and nonatretic mitral and aortic valves. The preparation is done at Stage 2 after Norwood, where Sano shunt is not taken down, and instead an internal right pulmonary artery band is placed at its origin. The mitral valve pathology is surgically corrected (commissurotomy, papillary muscle split, leaflet freeing, and augmentation), aortic valvotomy is done, endocardial fibroelastosis is resected. These children then subsequently are evaluated by the magnetic resonance imaging. Once the LVEDV is greater than 40 ml/m2, the Norwood is taken down and reconstruction is performed. Case selection is the most important aspect of this approach.
| Criss Cross Atrio-Ventricular Connections|| |
Criss-cross heart is a rare congenital anomaly of cardiac rotation resulting in crossing of ventricular inlets and drainage of the atria into contralaterally located ventricles. The AV and VA connections can be concordant or discordant. There can be either side-by-side or superior-inferior ventricular arrangement [Figure 8]. Most of the times such a complex anatomy results in functional single ventricle; however, it may be occasionally possible to achieve two ventricle repairs.
|Figure 8: Criss cross AV connections. Subcostal long-axis view shows dextrocardia, superior right ventricle (RV), and inferior left ventricle (LV). RA: Right atrium, LA: Left atrium|
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Choice of surgery in criss-cross heart is based on resultant ventricular mass and presence of associated limiting malformations and not the presence of ventricular rotation itself. Most children need intervention in early infancy due to restrictive pulmonary blood flow. Definitive repair is possible only in some. Largely, repairs are palliative in nature due to the presence of hypoplastic tricuspid valve or RV or straddling.
| Corrective Surgery|| |
Corrective surgery involves septation of the dominant ventricle (usually the LV) or anatomical single ventricle, with an aim of establishing a biventricular physiology. Goals are to achieve two good sized ventricles supporting respective circulations without inflow and outflow obstructions. The septation site is determined by the anatomy of the tensor apparatus of the AV valves, position of the VSD, conduction bundle, and semilunar valves. Restrictive VSD needs to be enlarged prior to septation. Smaller infants usually undergo a two-stage procedure, with Stage 1 comprising of septating the ventricle with a fenestrated patch and pulmonary artery band, and Stage 2 involving closure of fenestration and band removal.
| Straddling and Over-riding Atrio-Ventricular Valves|| |
When the tensor apparatus of either mitral or tricuspid valve is attached to the other side of the interventricular septum, it is called straddling [Figure 9]. If one of the AV valves is committed to more than one ventricle, its termed over riding. Both pathologies are often noted simultaneously. Extreme overriding results in double-inlet ventricles. Various degrees of overriding and straddling can be present in association with complex AVSD, AV discordant hearts and in those associated with hypoplastic ventricles. The presence of either straddling or over riding not only makes surgical repair difficult but impossible at times. Surgical planning must be highly individualized.
|Figure 9: Straddling of tricuspid valve. Apical four-chamber view: RA: Right atrium, LV: Left ventricle, RV: Right ventricle, STL: Septal tricuspid valve leaflet straddling and attached to papillary muscles on LV free wall|
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Classification of straddling:
- Type A: Chordae insert into the contralateral ventricle near the crest of the ventricular septum within a few millimeters of the apparent septal midline
- Type B: Chordae insert into the contralateral ventricle along the ventricular septum distant from the septal midline
- Type C: Chordae insert onto the free wall or papillary muscles of the contralateral ventricle.
Grading of overriding:
- Minor override: Less than 50% annulus is committed to contra lateral ventricle
- Major override: Approximately 50% annulus is committed to either ventricles
- DILV: More than 50% both AV valves committed to single ventricle.
| Outflow Tract Abnormalities|| |
Double outlet ventricles are described elsewhere. Extreme hypoplasia or atresia of pulmonary or aortic valve atresia is associated with right or LV hypoplasia, respectively. Aortic atresia is discussed along with HLHS. Pulmonary atresia is often associated with a ventricular septal defect. Their presentation and management are similar to tetralogy of Fallot.
Pulmonary atresia with intact interventricular septum
At one end of the spectrum, a neonate may have a membranous valvar pulmonary atresia with good sized RV and tricuspid valve, [Figure 10] and at the other end, there can be extreme RV hypoplasia, atretic or severely hypoplastic tricuspid valve with or without RV dependent coronary circulation. Following associated factors need to be assessed in these patients.
|Figure 10: Pulmonary atresia. Modified parasternal long-axis view. LA: Left atrium, LV: left ventricle, RV: Right ventricle, PDA: Patent ductus arteriosus. Arrow shows atretic pulmonary valve|
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- Tricuspid valve: Size, morphology, and function of tricuspid valve should be assessed. While Z score of up to -2 may be adequate to achieve an anatomical repair, severe degrees of hypoplasia will preclude a 2-ventricle repair and often need palliative procedures. If an abnormality of function is diagnosed, possible repair should be considered [Figure 11]
- Adequacy of size and morphology of RV: a favorable RV has an inlet, trabecular and an outflow region, should have good volume and is often apex forming [Figure 11]
- RV dependent coronary circulation: in patients with severe RV hypoplasia and functional tricuspid valve, the RV pressure may be extremely high and the coronary artery can have retrograde flow through RV sinusoids. There can be associated atresia or stenosis of proximal coronary arteries. Relief of RV pressure by pulmonary valvotomy can result in coronary insufficiency and undesirable outcome. The presence of RVDCC must be delt with caution while taking treatment decisions.
|Figure 11: Pulmonary atresia with intact ventricular septum. Apical four-chamber view shows with hypoplastic right ventricle (RV) and good-sized tricuspid valve. LV: Left ventricle, LA: Left atrium, RA: Right atrium|
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Pulmonary atresia with intact septum is treated by a combination of various options in the first stage. These include pulmonary valvotomy (open/closed), transannular patch, patent ductus arteriosus ligation, modified BT shunt, and atrial septectomy. The choice of these procedures depends upon the anatomy (especially size and morphology of RV and tricuspid valve). If the RV is adequately developed, these children undergo staged one and half ventricle repair, which includes ASD closure and a bidirectional cavopulmonary shunt as a definitive surgical correction. For the severely hypoplastic ventricles, a completion Fontan is performed.
| Clinical Presentations of Complex Congenital Heart Defect|| |
Despite wide range of abnormality of underlying anatomy, most patients present with similar clinical features. Various clinical presentations are possible.
A neonate presenting with duct dependent circulation
Fetal Cardiac blood flow is in parallel circulation due to patent foramen ovale, ductus venous and ductus arteriosus. The complex cardiac abnormality is generally compatible with fetal life due to this parallel circulation, but present as an acute emergency as soon as the ductus arteriosus closes after birth. Lesions with Duct dependent pulmonary circulation (DDPC) present with acute onset cyanosis that do not respond to oxygen and show pulmonary oligemia on chest roentgenogram. Those with duct dependent systemic circulation (DDSC) present with cardiogenic shock but minimal hypoxia. Prostaglandin E1 infusion should be started immediately to maintain oxygenation and perfusion in both the subsets.
Examples of Duct dependent systemic circulation and duct dependent pulmonary circulation [Table 2].
|Table 2: Examples of duct-dependent systemic circulation and duct-dependent pulmonary circulation|
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CCHDs which are not duct dependent, present in early infancy with clinical features of increased or decreased pulmonary blood flow. Clinical features of decreased pulmonary blood flow include progressive cyanosis and clubbing, cyanotic spells, fatigue, polycythemia, pulmonary oligemia and stunted growth. Clinical features of increased pulmonary blood flow include failure to thrive, recurrent respiratory infections, tachypnea, dyspnea on exertion, cardiomegaly, tender hepatomegaly, left or right heart failure and pulmonary plethora on chest roentgenogram. Further management should be towards optimization of pulmonary blood flow to as close to physiological limits as possible with an aim to protect pulmonary vascular bed from adverse effects of long-standing pulmonary hypertension.
| Surgery for Complex Congenital Heart Defects|| |
While every effort should be made to establish an anatomical repair in all CCHDs, it may often not be possible to do so due to unfavorable anatomy. Such patients are usually palliated towards preserving cardiac circulation as a single ventricle pathway [Figure 12]. Prerequisites for corrective surgery for CCHD are [Table 3].
|Figure 12: Single ventricle palliation pathway. As Stage 1 palliation, pulmonary blood flow is optimized by either systemic to pulmonary shunt or pulmonary artery band in the neonatal period or early infancy. By about 3–6 months age, bidirectional Glenn shunt is performed and finally completion of total cavopulmonary connection or Fontan surgery is performed|
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- Systemic and pulmonary venous return should be routable to systemic and pulmonary arteries respectively
- Two separate functional AV valves are present or can be created
- Two good sized ventricles should be present
- Ventricular septal defect should be positioned or surgically routed in such a way that aorta and pulmonary artery can be aligned to LV and RVs respectively.
| Palliative Procedures and Staged Single Ventricle Repair|| |
Systemic to pulmonary artery shunts (Blalock Taussing shunt)
In complex congenital heart diseases, shunts are performed in neonates or young infants, when corrective surgery is not possible or needs to be delayed. Duct stunting is an attractive alternative in select cases [Figure 13]. The aim of a BT shunt is to improve pulmonary blood flow and saturations. A standard systemic to pulmonary artery shunt involves a creation of an extra-anatomic pathway between a branch of aorta to branch pulmonary artery. However, if the origin and/or the insertion of the shunt is on the aorta or main pulmonary artery respectively, it is called a central shunt.
|Figure 13: Post patent ductus arteriosus stent in pulmonary atresia and intact interventricular septum. PA: Main pulmonary artery. Ao: Descending thoracic aorta, Arrow points to stent|
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Pulmonary artery band
A pulmonary artery band is a palliative procedure in neonates or young infants born with a high pulmonary blood flow in a single ventricle physiology who have florid heart failure. Though technically simple, adaptation to a pulmonary band physiology can be challenging. The optimal band size can be difficult to determine in neonates due to inherently high pulmonary vascular resistance, poor oxygenation, presence of lung infections. Saturations cannot be a guide in presence of single ventricle admixture lesions.
Bidirectional cavo-pulmonary shunt (Glenn shunt)
Glenn shunt constitutes the second stage of the palliative single ventricle correction in complex CHDs. It involves an end-side anastomosis of right superior venacava to the right pulmonary artery with an aim of diverting the upper body venous drainage to the pulmonary circulation bypassing the heart. The single most advantage of a Glenn shunt is improving oxygenation without significantly increasing pulmonary artery pressures or ventricular volume load. The prerequisite for Glenn shunt is an acceptable pulmonary vascular resistance.
Total cavo-pulmonary connection (Fontan operation)
A detailed discussion on Fontan physiology and the evolution of surgical strategies to accomplish that is beyond the scope of this article. During a Fontan operation, the entire systemic venous drainage is diverted to the pulmonary circulation bypassing the heart [Figure 14]. There are many ways to achieve this, but most commonly performed are the extracardiac Fontan using a conduit or the lateral tunnel Fontan using an intra-atrial baffle. A set of ‘10 commandments’ were proposed by Chaussat's for optimum surgical outcomes of Fontan operation and has been adopted, updated and modified multiple times to suit current needs.
|Figure 14: Post Fontan surgery: Suprasternal long-axis view. SVC: superior venacava, Con: Conduit from inferior vena cava to right pulmonary artery, RPA: Right pulmonary artery, LA: Part of left atrium, Ao: Aorta in cross section|
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| Conclusion|| |
A systematic approach to diagnosis describing segmental cardiac anatomy, functional status of valves and ventricles, adequate sizes of valves, chambers, outflow tracts, pulmonary and aortic valves, branch pulmonary arteries and aortic arch are essential before a decision to treat is made. While most lesions need staged palliative surgeries, a few rare lesions may be amenable to corrective repairs. Every effort should be made to identify patients suitable for corrective surgery as their long term prognosis is good.
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Conflicts of interest
There are no conflicts of interest.
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Anderson RH, Shinebourne EA, Gerlis LM. Criss-cross atrioventricular relationships producing paradoxical atrioventricular concordance or discordance. Circulation 1974;50:176-80.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]
[Table 1], [Table 2], [Table 3]