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Ann Thorac Surg 2000;69:S170-S179
© 2000 The Society of Thoracic Surgeons
a Division of Cardiovascular Surgery, The Montreal Children’s Hospital, McGill University, Montréal, Québec, Canada
b Department of Surgery, St. Christopher’s Hospital for Children, Philadelphia, Pennsylvania, USA
Address reprint requests to Dr Tchervenkov, Division of Cardiovascular Surgery, The Montreal Children’s Hospital, 2300 Tupper St, Room C-828, Montreal, PQ, Canada H3H 1P3
e-mail: ctchcvt{at}mch.mcgill.ca
Presented at the International Nomenclature and Database Conferences for Pediatric Cardiac Surgery, 1998–1999.
Abstract
Hypoplastic left heart syndrome (HLHS) encompasses a spectrum of structural cardiac malformations that are characterized by severe underdevelopment of the structures in the left heart-aorta complex, including the left ventricular cavity and mass. The severe end of the spectrum consists of aortic atresia and mitral atresia with a nonexistent left ventricle, whereas at the mild end patients have aortic valve and mitral valve hypoplasia without intrinsic valve stenosis, and milder degrees of left ventricular hypoplasia, recently described as hypoplastic left heart complex (HLHC). Although the overwhelming majority of the patients can only have a univentricular repair, a small minority of patients with HLHS, particularly those that are described as having HLHC, may be candidates for biventricular repair.
In this paper, the extant nomenclature for HLHS is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Nomenclature and Database Committee and representatives from the European Association for Cardiothoracic Surgery. Efforts were made to include all relevant nomenclature categories using synonyms where appropriate. A comprehensive database set is presented, which is based on a hierarchical scheme. Data are entered at various levels of complexity and detail that can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented which will allow for data sharing, and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.
I. Background
Hypoplastic left heart syndrome (HLHS) is a term that has been used to describe a heterogeneous group of cardiac malformations that consist of various degrees of underdevelopment of the left heart-aorta complex, resulting in significant obstruction to blood flow and the inability of the left heart to support the systemic circulation. Because HLHS is often imprecisely defined, and is used interchangeably with a variety of other terms, there exists a degree of confusion, a lack of consistency, and therefore significant difficulty in comparing one clinical series to another. In this overview, we will attempt to summarize how the terminology has evolved over the years and propose a new classification that will hopefully lead to more accuracy, precision and consistency.
Historical perspectives and review of nomenclature
The tendency of hypoplastic and obstructive lesions in the left heart-aorta complex to occur together was first appreciated by Lev [1] in 1952, and he used the term hypoplasia of the aortic tract complexes. The basic features of this diagnostic grouping were: (1) the ascending and transverse portions of the aorta and the aortic orifice are small; (2) the pulmonary artery and its orifice are large; and (3) there is no transposition of the arterial trunks. Based on the examination of 40 pathologic hearts he classified hypoplasia of the aortic tract complexes as follows: (1) isolated hypoplasia of the aorta; (2) hypoplasia of the aorta with septal defects; (3) hypoplasia of the aorta with aortic atresia (AA) or stenosis without mitral atresia; and (4) hypoplasia of the aorta with AA or stenosis with mitral atresia.
The physiological features of this group of patients are lack of left ventricular and aortic flow, and an increase in right ventricular flow. These become markedly exaggerated where there is aortic stenosis or atresia.
In 1966, Lev [2] narrowed this complex to: (1) severe aortic stenosis or atresia with open mitral valve (MV); and (2) aortic and mitral atresia.
In 1984, Bharati and Lev [3] published their study of 230 hearts with hypoplasia of the aortic tract complex and concluded that from an anatomical point of view the complex of AA with mitral stenosis and that of severe aortic stenosis and mitral stenosis were almost identical, and could be considered as one, though distinct from the complex of aortic and mitral atresia.
The term HLHS was first used by Noonan and Nadas [4] in 1958 to include anomalies with an obstructive lesion (atresia or stenosis) on the left side of the heart. The original definition was meant to be in the broadest sense, including an entire spectrum of hypoplasia of the left heart, ranging from aortic and mitral atresia with a vestigial left ventricle (LV) to lesser forms of mild underdevelopment of the LV. Based on the analysis of 101 postmortem cases five groups were created: (1) aortic valve (AV) atresia; (2) mitral atresia; (3) mitral stenosis; (4) aortic arch atresia; and (5) hypoplasia of the aortic arch.
The last group was by far the largest with 71 cases. The authors concluded, based on the clinical and autopsy findings, that there are similarities in clinical presentation. The diagnosis should be suspected if there is the sudden onset of right-sided and left-sided congestive failure in a young infant with mild cyanosis, a nonspecific heart murmur, and either weak pulses in all extremities or relative hypertension in the arm. The clinical recognition of the syndrome is not difficult in most cases, but making the specific diagnosis of the exact anatomic defect requires a cardiac imaging modality.
In 1959, Currarino and associates [5] used the term hypoplasia of the left heart complex in describing the pathologic findings in two neonates dying in the first week of life. These findings consisted of aortic and mitral stenosis, hypoplastic LV with endocardial fibroelastosis, and a hypoplastic aorta from its origin until the insertion of the ductus. Both patients exhibited differential cyanosis with a pink right upper quadrant of the trunk, the right side of the head and neck and the right arm, with the rest of the body being cyanotic. It is interesting to note that both patients had complete obliteration of the foramen ovale, a finding implicated in the etiology of this complex by causing deranged flow patterns in fetal life.
Of the terms used in these early reports, HLHS is the one that became accepted, and the one widely used today. This is not surprising because this was the term used in the early 1980s, by surgeons working to find a surgical solution to this lethal malformation. Both Norwood and colleagues [6, 7] and Doty and colleagues [8] used the term HLHS in their early surgical reports, and this is probably the major reason why it has gained such widespread acceptance and utilization, despite its lack of specificity and precise and consistent definition.
From early on, there was a controversy as to what constitutes HLHS. Some defined it in very narrow terms, as atresia of the aortic or mitral valve, or both, with normally related great arteries and intact ventricular septum [9]. Their argument was to avoid confusion among pediatricians, cardiologists, and surgeons, and therefore to include only those cases with minute LVs, clearly incapable of supporting the systemic circulation. Others have used a much more general definition of underdevelopment, or absence of one or several anatomic characteristics of the left side of the heart: atresia or hypoplasia of the left atrial outlet, LV, AV, and aortic arch [10]. Their argument, on the other hand, was to avoid focusing attention on the hopeless form of HLHS, but rather emphasize that nearly one half of their cases are salvageable by intensive medical management, combined with surgical palliation.
The search for a surgical solution for the severe end of the spectrum of HLHS intensified in the 1980s, and culminated in the development of both neonatal heart transplantation and the Norwood procedure. The Norwood procedure encompasses the following principles: (1) unobstructed egress from the heart into the systemic circulation with the potential for growth of the reconstructed neoaorta; (2) unobstructed pulmonary venous return into the right atrium and right ventricle (RV); and (3) control of pulmonary circulation through a calibrated shunt.
The establishment of the Norwood operation has also resulted in its synonymous use with HLHS to imply the inability of the left heart to support the systemic circulation. However the recent application of the Norwood operation for lesions other than HLHS, such as tricuspid atresia with transposition of the great arteries and aortic arch obstruction, or two-ventricle hearts in which there is inability to perform a biventricular repair (some forms of double-outlet right ventricle with remote ventricular septal defect (VSD), hearts with straddling AV, severely unbalanced AV septal defects), clearly demonstrates that its use is no longer synonymous with HLHS [11–13].
The lack of specificity of HLHS has led Kirklin and Barratt-Boyes [14] to use the term in its widest meaning. They stratified HLHS according to the number of obstructions in the left heart-aorta complex and suggested a classification with four classes. Classes I and II consist of one and two obstructions of the left heart respectively, class III has more than two obstructions with LV hypoplasia, and class IV consists of AA.
The severe forms of HLHS were inoperable for many years, whereas the simpler forms of HLHS, such as coarctation of the aorta or aortic stenosis had specific surgical procedures directed at the specific level of obstruction. With the advent of the Norwood operation and the Fontan operation, surgical treatment for the severe HLHS became possible. Because of this, the term HLHS has been increasingly used to refer to the extreme forms with RV dependent systemic circulation where a two-ventricle repair is not possible. This has brought into question the precise meaning of the term HLHS and how it should be used. The use of HLHS, as originally defined, tends to be impractical since it lacks specificity and requires further specific definition in each case. This requirement defeats the purpose of the diagnosis. In milder forms, the term of HLHS is not routinely used, but rather the specific diagnoses such as aortic stenosis, coarctation of the aorta, or interrupted aortic arch. On the other hand when dealing with the severe form, the opposite is true, with the term HLHS being used frequently to clump together several diagnoses that have a RV dependent systemic circulation, such as AA, mitral atresia with aortic stenosis, mitral stenosis with severe LV hypoplasia in common.
Though originally used by Noonan and associates [4], to describe a broad spectrum of anomalies, including one or multiple levels of left heart obstruction or hypoplasia, the term HLHS in current use fails to encompass a small group of patients that are inadequately described by any of the currently existing terminology [15–20]. To fill this gap, Tchervenkov and associates [21] introduced the term of hypoplastic left heart complex (HLHC) in 1998, to describe patients with hypoplasia of the left heart structures, without intrinsic valve stenosis or atresia, and with forward flow in the ascending aorta into the branches of the aortic arch, with only the descending aortic circulation being usually, but not always, RV dependent. Biventricular repair was possible for most of these patients. It is interesting to note that in the original paper on HLHS by Noonan and Nadas [4], the largest group of patients (71 patients) was that with hypoplasia of the aortic arch. These patients had a small but functioning LV, and a minority had associated aortic or mitral stenosis. It is likely that many of the patients in this group fall within the diagnosis of HLHC.
Patients with HLHC also bear some similarities to a developmental complex described by Shone and associates [22]. Shone’s report, based on 8 cases, described the tendency of the following four obstructive, or potentially obstructive, conditions to coexist: (1) supravalvar ring of the left atrium; (2) a "parachute" deformity of the mitral valve; (3) subaortic stenosis; and (4) aortic coarctation.
Only 2 cases exhibited all four conditions, and the remaining 6 cases exhibited two or three of the anomalies. Of the individual anomalies, subaortic stenosis and a supravalvar ring of the left atrium were present in all cases, however they were considered functionally significant in only 6 and 3 cases, respectively. On the other hand a parachute mitral valve and coarctation were present in only 4 cases, and were considered functionally significant in 3. Hypoplasia of the various structures of the left heart-aorta complex, particularly of the LV, which is a fundamental feature in HLHC, is not mentioned in Shone’s paper.
The overwhelming majority of patients with HLHS have an intact ventricular septum or, if a VSD is present, it is usually small and insignificant. When a large VSD is present, the LV is usually well-developed and a biventricular repair is generally possible. In a review by Moodie and associates [23] of 172 patients with AA, 12 patients (7%) were found to have a large VSD with a well-developed LV. It is questionable as to whether these patients should be classified as HLHS. In his classic report on palliative operation for HLHS, describing the management of three patients, Norwood and associates used the term aortic atresia (AA) intact ventricular septum (IVS) to distinguish the common forms of HLHS from their one case of aortic atresia, VSD [6]. Unfortunately the terms AA/IVS and AA/VSD have not caught on like pulmonary atresia (PA)/IVS and PA/VSD, probably due to the rarity of the patients with AA/VSD. Nevertheless, it is probably wise to include the cases with AA/VSD under the data system for HLHS, despite the debate as to whether they truly represent HLHS, because of the inability to group them with any other congenital lesion.
Definitions of terminology
It would be useful to examine the definition of the terms syndrome and complex before going any further. A syndrome is a group of signs and symptoms that occur together and characterize a particular abnormality. A complex is a whole, made up of complicated or interrelated parts. Lev pointed out the tendency of abnormalities to group themselves together [2]. He suggested that a complex is a single, or group of anomalies, which have the tendency to occur together, and the effects on the endocardium, myocardium, valves, epicardium, and conduction system. Therefore Lev used the term hypoplasia of the aortic tract complex. The definition containing the word complex may be semantically more accurate than the one using the word syndrome. From a practical point of view the use of the term HLHS is so widespread and well established, that it will be extremely difficult, and perhaps not wise to try to change it. On the other hand it would be important to define HLHS in much narrower terms than the definition proposed by Kirklin and Barratt-Boyes [14]. We propose the following definition:
HLHS is a spectrum of cardiac malformations, characterized by a severe underdevelopment of the left heart-aorta complex, consisting of aortic and/or mitral valve atresia, stenosis, or hypoplasia with marked hypoplasia or absence of the LV, and hypoplasia of the ascending aorta and of the aortic arch.
At the milder end of the spectrum are patients with HLHC [21] or patients with critical aortic stenosis and left ventricular hypoplasia [24]. At the severe end of the spectrum patients have aortic and mitral atresia with a nonexistent left ventricle. We propose the following definition for HLHC:
HLHC is a subset of patients at the favorable end of the spectrum of HLHS characterized by hypoplasia of the structures of the left heart-aorta complex, consisting of aortic and mitral valve hypoplasia without valve stenosis or atresia, hypoplasia of the left ventricle, hypoplasia of the left ventricular outflow tract, hypoplasia of the ascending aorta and of the aortic arch, with or without coarctation of the aorta.
The reader is advised that other anomalies, such as severely unbalanced AV septal defect, double-outlet right ventricle with LV hypoplasia, tricuspid atresia with transposition, and univentricular hearts with LV morphology, with or without aortic arch obstruction, are all considered within other sections of this supplement, consistent with the fact that these anomalies are not HLHS.
Pathophysiology
At the severe end of the spectrum, the systemic circulation is completely RV-ductal dependent, with retrograde flow in the aortic arch and the ascending aorta. This is the case in aortic atresia and mitral atresia or stenosis. At the mild end of the spectrum, the systemic circulation may be partially RV-PDA dependent as in aortic stenosis and mitral stenosis, aortic stenosis with LV hypoplasia, or in the HLHC. The descending aortic circulation is RV-PDA dependent, and the ascending aorta and various portions of the aortic arch and branches are supplied by forward flow from the LV. In a very few patients, the systemic circulation may be entirely LV dependent in the presence of lesser degrees of obstruction through the left heart, usually by virtue of hypoplasia of the various structures such as in the HLHC.
In the vast majority of patients with HLHS the only reconstruction is the univentricular approach with the Norwood operation in the neonatal period, to transfer the systemic circulation over the RV, followed eventually by the Fontan operation. However, biventricular repair may be possible for some patients at the mild end of HLHS, such as in patients with critical aortic stenosis and adequate size of the small LV as defined by the Rhodes’ criteria [24], and for most of the patients with HLHC [21].
II. Analysis: a unified HLHS nomenclature system
HLHS hierarchy level 1
HLHS hierarchy level 2
The difference between the categories: Hypoplastic left heart syndrome (HLHS), Aortic stenosis + Mitral stenosis, and Hypoplastic left heart syndrome (HLHS), Hypoplastic AV + MV + LV (HLHC) can be difficult and in some cases arbitrary. Aortic stenosis + mitral stenosis infers that there is commissural fusion and true stenosis of the valves. Hypoplasia of the AV, MV, and the LV indicates that the valves are small, but not stenotic per se. This has therapeutic considerations and potential consequences since some of these HLHC patients may be candidates for biventricular repair, while those patients with true aortic stenosis and mitral stenosis are generally not candidates for biventricular repair.
HLHS hierarchy level 3
HLHS hierarchy level 4
Additional HLHS modifiers
III. Nomenclature for treatment options
Surgical treatment options for HLHS
Three surgical approaches have evolved over the years and are available today: 1) multistage reconstructive operation based on a single ventricle physiology, popularized by Norwood [25]; 2) cardiac replacement championed by Bailey [26]; and 3) biventricular repair, recently reported by Tchervenkov and associates [21], used for the patients at the mild end of the spectrum of HLHS (those with HLHC) [21] as well as for the patients with AA, VSD and well-developed LV (not technically HLHS) [27, 28].
While the first two approaches can be applied to any patient with HLHS, the biventricular approach can be used in very few patients, and requires an extremely careful evaluation and selection process.
Much of the debate over the last 15 years has been centered on the advantages and disadvantages of the Norwood operation and neonatal cardiac transplantation. Both approaches are based on entirely different surgical philosophies. Different centers tend to favor one or the other of these surgical approaches, while some offer both and let the parents decide [29]. Still some centers offer a third nonsurgical option of supportive care, called by some compassionate care [30] and by others passive euthanasia [31]. These options raise a number of ethical issues that are not in the scope of this paper, and will not be further discussed.
Multistage reconstructive operation
The first palliative operation for HLHS was reported in 1970 by Cayler and associates [32], and consisted of an anastomosis between the right pulmonary artery and the ascending aorta and bilateral pulmonary artery banding, with the patient being alive at 3 years of age [33]. An early attempt at surgical treatment of HLHS, by Norwood in 1977, involved a modified Glenn shunt, side-to-side anastomosis between the aorta and main pulmonary artery, and banding of the left pulmonary artery, with the patient dying 7 hours postoperatively from severe arterial desaturation and acidosis [6]. Doty also attempted to connect the partitioned right atrium, collecting the inferior and superior vena cavae to the distal pulmonary artery with a conduit, and connecting the proximal pulmonary artery and the aorta with another conduit in 6 babies [34, 35]. Like Norwood’s patient, all of his patients died of low cardiac output related to elevated pulmonary vascular resistance in the neonatal period. These unfavorable early experiences clearly demonstrated that a multistage approach would be necessary.
The earliest first-stage operations by Norwood and associates [6] had some similarity to an operation performed by Litwin and associates [36] for interrupted aortic arch in which a nonvalved conduit was placed between the main pulmonary artery and the descending aorta, and a pulmonary artery band was placed distal to the conduit. In 1980, Norwood and associates proposed the placement of a valved conduit between the RV outflow tract and the descending aorta, and the placement of a pulmonary artery band [6]. This approach was quickly abandoned by Norwood and associates in favor of a more direct technique reported in 1981 [7]. The main pulmonary artery was transected before its bifurcation, and was anastomosed directly to an incision in the ascending aorta and aortic arch without foreign material. The operation was completed by the construction of a 4-mm central aortopulmonary shunt. We consider this to be the earliest Norwood operation. Of the 16 patients undergoing the first stage reconstruction in this report, only a minority survived, and only one underwent the Fontan operation at the age of 14 months and died 2 days later of low cardiac output.
At around the same time, Doty and associates [8] used a tubular graft (Gore-Tex; W. L. Gore & Assoc, Flagstaff, AZ) between the proximal pulmonary artery and the aortic arch, and a calibrated opening (3 mm) in the graft brought in continuity with the distal pulmonary artery to provide balanced pulmonary and systemic blood flow. The patient died suddenly 12 weeks after the operation. The autopsy revealed the calibrated opening in the graft had narrowed considerably by neointima growth, down to only 1 mm. In addition, this technique had the limitation in dealing with the problem of the diminutive ascending aorta in providing adequate coronary blood flow. Doty recognized these limitations and stated that Norwood’s technique may be better in dealing with both those problems [35].
In 1980, Norwood and associates [6] spelled out the principles of the first stage operation as follows: (1) establishment of a permanent communication between the right ventricle and aorta; (2) limitation of pulmonary blood flow to attenuate the pulmonary vascular changes secondary to elevated pulmonary blood flow and pressure; and (3) insurance of a satisfactory interatrial communication.
These principles have remained remarkably constant over the last 20 years and still apply today. Subsequently, at a second operation the physiologic correction would be carried out by separating the systemic and the pulmonary circulations (Fontan procedure) [6]. In the last 10 years, an intermediate stage has been added, in the form of a hemi-Fontan operation or a bidirectional Glenn shunt, before the Fontan operation, increasing the multistage reconstructive surgical approach to 3 operations [37].
The first patient with HLHS to successfully undergo and survive the Fontan operation was reported by Norwood and colleagues [25] in 1983 in the New England Journal of Medicine, and finally offered renewed hope for this lethal cardiac malformation.
Since the early 1980s, there have also been several modifications to Norwood’s initial operation, in order to more reliably fulfill the surgical criteria for the stage I palliation, and to prepare the patient to be an optimal candidate for the Fontan operation. These have included the following: (1) use of homograft patch to reconstruct the aortic arch and the opened ascending aorta and bring them over the divided proximal main pulmonary artery [27, 37]; (2) use of complete tube from the proximal pulmonary artery to the aortic arch [27]; (3) techniques of direct reconstruction of aortic arch and ascending aorta without prosthetic material [7, 38, 39]; and (4) direct anastomosis between the proximal main pulmonary artery and the aortic arch augmented distally with small homograft patch (personal experience, C.I.T).
With respect to the shunt there have also been different shunt types utilized, such as a central shunt, a modified Blalock-Taussig shunt, a classical Blalock-Taussig shunt [40], and, rarely in an infant, a concomitant Glenn shunt (personal experience, C.I.T). The shunt sizes have tended to get smaller with time, initially a 4 mm was standard, but more recently a 3.5 mm, and now even a 3 mm shunt is being used.
In earlier experiences, the Fontan operation was performed as the 2nd operation, usually around 18 to 24 months of age [37]. Since the early 1990s, an intermediate stage, called the 2nd stage, was added, before proceeding with the Fontan operation [27, 37]. This was with the intent to decrease the volume load on the systemic RV at an earlier stage, by replacing the systemic-to-pulmonary shunt with a cavopulmonary shunt. The surgical technique was by either a bidirectional cavopulmonary anastomosis [27] or a hemi-Fontan procedure [37]. These procedures are usually planned around 6 months of age, but have been successfully performed in patients as young as 1 month of age [40].
The final and 3rd stage is the completion Fontan operation, usually of the lateral tunnel type [37, 40] or extracardiac tunnel [41, 42]. This may include either a fenestration in the interatrial baffle [40] or the exclusion f one or more hepatic veins from the systemic venous pathway [37]. Detailed descriptions of the various techniques of the Fontan operation are not part of the scope of this paper, and will be found in the manuscript on single ventricle in this supplement.
Cardiac replacement
The pioneering work of Bailey and associates [26, 43] has resulted in the establishment of cardiac transplantation as a viable alternative to multistage reconstructive operation. The main advantage of cardiac transplantation is the replacement, in one operation, of a single RV heart with its highly abnormal circulation, by a normal four chamber heart with normal physiology. Although survival following transplantation has been excellent, this approach has been seriously limited by the grossly inadequate availability of donor hearts. Furthermore this approach requires lifelong immunosuppression, with the attendant risks of rejection, infection, graft atherosclerosis, and malignancies.
Biventricular repair
The diagnosis of HLHS frequently suggests treatment in the form of the Norwood operation, without consideration of biventricular repair. Recently Tchervenkov and associates [21] identified a subgroup of patients at the mild end of the spectrum of HLHS, most of whom have undergone successful biventricular repair. These patients had hypoplasia of all the structures of the left heart-aorta complex without intrinsic valve stenosis and were collectively called HLHC [21]. They usually have partial RV PDA dependent systemic circulation of the descending aorta, and forward flow through the hypoplastic left heart into the ascending aorta and the branches of the aortic arch, a physiology similar to the one observed in patients with interrupted aortic arch. The primary biventricular repair has consisted of extensive aortic arch and ascending aorta enlargement with a pulmonary homograft patch, closure of the interventricular and interatrial communications, and conservative approach for the left ventricular outflow tract obstruction (LVOTO) [21]. Many of these patients have required reoperations for recurrent LVOTO, despite remarkable growth of the LV.
Another group of patients successfully undergoing primary biventricular repair, are those with AA, VSD and well-developed LV [27, 28]. It is questionable whether patients with well-developed LV can be considered as HLHS, but are included in this paper for a lack of a better place in the nomenclature. The technique described by Austen and associates [28] involves closure of the VSD into the pulmonary artery, which after its division, before the bifurcation, is connected with a tube graft to the aortic arch, distal ascending aorta, and the proximal descending aorta. The RV is then connected with a valved homograft to the distal pulmonary artery, thus achieving a biventricular repair.
Finally the last group of patients who may be candidates for a biventricular repair are those with critical aortic stenosis and LV hypoplasia, that fulfill the Rhodes’ criteria for LV size [24]. It is controversial as to whether these patients are considered as HLHS, or whether they re included with the critical aortic stenosis group.
Patients with HLHC, on the other hand, have aortic annular hypoplasia without aortic valve stenosis. It is becoming increasingly clear that the Rhodes’ criteria for LV size, which pertain to cases of aortic stenosis, do not accurately predict suitability for biventricular repair of hearts with HLHC [19, 21].
HLHS treatment hierarchy level 1
Hierarchy level 1 definitions
Norwood stage 1
An aortopulmonary connection and neoaortic arch reconstruction resulting in univentricular physiology and pulmonary blood flow controlled with a calibrated systemic-to-pulmonary artery shunt.
HLHS biventricular repair
Performed in a small number of patients who have small but adequately sized left ventricles to support the systemic circulation. These patients usually have small, but not stenotic, aortic and/or MV. They may also require simultaneous and/or remote repair of the following LVOT: mitral stenosis (supravalvar, valvar, or subvalvar), subaortic stenosis, aortic stenosis, aortic arch hypoplasia, coarctation, or interrupted aortic arch. These concurrent operations can be coded separately within the database.
Orthotopic cardiac transplantation
Performed for HLHS with or without arch reconstruction, depending on the status of the aortic arch and degree of coarctation. Cardiac transplantation can be coded separately in the database under the cardiomyopathy section as described in the cardiomyopathy manuscript of this supplement.
The size, type, anatomic origin, and anatomic insertion of systemic-to-pulmonary artery shunts associated with the Norwood operation will be entered in a separate module of the database which has been defined and expanded in the single ventricle manuscript of this supplement. The choices are sufficiently large enough to warrant a comprehensive menu selection. The choices may also determine a risk stratification model that would help to determine the size of shunt relative to the patient’s size, the patient’s age, and the patient’s diagnosis.
HLHS treatment hierarchy level 2
Hierarchy level 2 definitions
Classic Norwood operation
Characterized by an aortopulmonary connection without aortic transection and a neoaortic reconstruction using homograft material. Pulmonary artery blood flow is by a calibrated systemic-to-pulmonary artery shunt.
Modified Norwood operation
Any number of operations which may include: aortic transection, aortopulmonary connection and neoaortic arch reconstruction without homograft material, or a combination of these techniques. Other modifications can include different methods of establishing calibrated systemic-to-pulmonary artery shunts and different methods of neoaortic arch reconstruction.
HLHS biventricular repair
Predicated on the assumption that the small left ventricle is large enough to support the systemic circulation acutely and has the potential for growth. Other important factors are that the AV and MV are small but not stenotic per se. Often, multiple operations to address the levels of relative obstruction of the left ventricular outflow tract are required to accomplish an acceptable biventricular repair.
HLHS biventricular repair, aortic coarctation repair
(Can be coded separately in addition to HLHS biventricular repair in the coarctation and interrupted aortic arch section of this supplement).
HLHS biventricular repair, aortic arch repair
(Can be coded separately in addition to HLHS biventricular repair in the coarctation and interrupted aortic arch section of this supplement).
HLHS biventricular repair, aortic valve repair
(Can be coded separately in addition to HLHS biventricular repair in the aortic valve disease section of this supplement).
HLHS biventricular repair, aortic valve replacement
(Can be coded separately in addition to HLHS biventricular repair in the aortic valve disease section of this supplement).
HLHS biventricular repair, MV repair
(Can be coded separately in addition to HLHS biventricular repair in the mitral valve disease section of this supplement).
HLHS biventricular repair, septal defect repair
(Can be coded separately in addition to HLHS biventricular repair in the atrial septal defect or ventricular septal defect sections of this supplement).
Transplant, heart, with transverse arch augmentation
(Can be coded separately in the cardiomyopathy section of this supplement).
Transplant, heart, without transverse arch augmentation
(Can be coded separately in the cardiomyopathy section of this supplement).
HLHS treatment hierarchy level 3
Additional comments regarding therapeutics
In addition to the above basic treatment options for HLHS, several other therapeutic issues must be addressed and coded in other areas of the database. First, a separate part of the database must allow for coding of incisions for this and all other diagnoses (median sternotomy, submammary incision, right thoracotomy, left thoracotomy, minimally invasive incisions, including partial sternotomy, parasternal incision, mini-thoracotomy, etc.). Second, a separate part of the database must allow for coding of cardiac incisions for this and all other diagnoses (aortotomy, pulmonary arteriotomy, right atriotomy, right ventriculotomy, left ventriculotomy, etc). Third, a separate module of the database must permit coding of patch materials (Dacron, Gore-Tex, bovine pericardium, autologous pericardium, gluteraldehyde fixated autologous pericardium, etc), conduit type, conduit materials, conduit size, and use of other biological or prosthetic materials.
Procedures directed at associated lesions (thymectomy, closure of patent foramen ovale, closure of atrial septal defect, etc) can be coded as additional or secondary procedures under the primary HLHS procedure.
Finally, details regarding management of cardiopulmonary bypass, myocardial protection, and associated issues will be recorded in another related and linked module of the database.
IV. Diagnosis and procedure short lists
V. Potential diagnostic related risk factors
Individual institutional series describing the outcome from surgical management of HLHS have identified a variety of demographic and diagnosis related risk factors. While not entirely consistent from one series to another, these generally include the following:
Preoperative
Risks for biventricular repair: size of mitral valve, presence of parachute mitral valve, size of LV cavity, presence of LVOTO + size of LVOT, size of aortic annulus, presence of aortic stenosis.
Intraoperative
Postoperative
Database should include a list of postoperative variables common to all open cardiac surgical procedures.
VI. Outcome reports
References
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