Borderline left ventricle *

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1 European Journal of Cardio-thoracic Surgery 27 (2005) Review Borderline left ventricle * Antonio F. Corno* Department of Cardiothoracic Surgery, Alder Hey Royal Children Hospital, Liverpool, L12 2AP, UK Received 13 August 2004; received in revised form 1 October 2004; accepted 4 October 2004 Summary: The first problem to solve when dealing with the topic borderline left ventricle is to find the appropriate definition. Several parameters have been taken into consideration, either morphometric (diameter of the mitral valve, indexed mitral valve area, left ventricular inflow dimension, left ventricular cross-sectional area, ratio between the apex-to-base left ventricular dimension and right ventricular dimension, left ventricular long axis to heart long axis ratio, left ventricular end diastolic volume, left ventricular mass index, ratio of the right/left ventricular wall thickness, presence of endocardial fibroelastosis, cardiac apex not formed by the left ventricle, diameter of the ventriculo-aortic junction, diameter of the aortic valve annulus and indexed aortic root diameter) as well as functional (left ventricular ejection fraction, left ventricular end diastolic pressure, mean pulmonary artery pressure, direction of the blood flow in the ascending aorta and at the level of the patent ductus arteriosus). Pre-operative determination whether the left ventricle is adequate to sustain the systemic circulation, or it may became adequate with the available surgical approaches, and therefore a bi-ventricular type of repair is feasible, can be extremely difficult, particularly in the presence of a borderline left ventricle. In the clinical practice pediatric cardiologists and cardiac surgeons are faced with the problem of the borderline left ventricle in four different groups of congenital heart defects: (a) aortic valve stenosis, (b) aortic coarctation, with or without hypoplastic aortic arch, (c) hypoplastic left heart complex, (d) right ventricular pressure and/or volume overload. In all the above situations in the presence of a left ventricle smaller than normal a very exhaustive approach has been reviewed in the decision making process, taking in account the literature reports as well as the personal experience. In each patient with borderline left ventricle the elements to be considered for the decision making process between uni- and bi-ventricular type of repair, or for less ideal options of management, are the following: morphometric and functional parameters, hemodynamic data, available surgical options, results of the personal and institutional experience. q 2004 Elsevier B.V. All rights reserved. Keywords: Aortic valve; Congenital heart disease; Mitral valve; Pediatric; Surgery; Ventricle It is our choices, Harry, that show what we truly are, far more than our abilities. Albus Dumbledore, Headmaster at Howgwarts in Harry Potter and the Chamber of Secrets by J.K. Rowling. 1. Introduction The first problem to solve when dealing with the topic borderline left ventricle is to find the appropriate definition. On the English Dictionary Collins [1] borderline is defined as an indeterminate position between two conditions and also on the edge of one category and verging on another. * Paper presented at the 39th Annual Meeting of the Association of European Paediatric Cardiologists, Munich, May 18 22, *Tel.: C ; fax: C address: antonio.corno@rlc.nhs.uk If these definitions were applied to the left ventricle, the borderline left ventricle should be considered as a ventricle with an indeterminate position between normal and small, but also a ventricle on the edge of the category of normal size, but verging on small size. In order to give a quantitative evaluation, able to allow a scientific approach to the problem, tables with normal left ventricular dimensions and z-values, with standard deviations from the normal values, have been provided in the last edition of a book generally accepted as one of the main references in cardiac surgery, in relationship with the body surface area [2]. The same book reported as criteria to define a left ventricle as hypoplastic, therefore inadequate to sustain a bi-ventricular type of repair, the association of indexed mitral valve area!4.75 cm 2 /m 2, left ventricular inflow dimension!25 mm, ratio between the apex-to-base left ventricular dimension and right ventricular dimension!0.8, and aortic annulus!6 mm[2]. Despite the above criteria have been provided as guidelines, a much more exhaustive approach is needed in /$ - see front matter q 2004 Elsevier B.V. All rights reserved. doi: /j.ejcts

2 68 A.F. Corno / European Journal of Cardio-thoracic Surgery 27 (2005) the decision making process for patients with a left ventricle smaller than normal. This review article is an attempt at providing the elements, derived from the literature and from the personal experience, useful to decide among the available surgical options. In the clinical practice pediatric cardiologists and cardiac surgeons are faced with the problem of the borderline left ventricle in four different groups of congenital heart defects with ventriculo-arterial concordance: aortic valve stenosis aortic coarctation, with or without hypoplastic aortic arch hypoplastic left heart complex right ventricular pressure and/or volume overload Patients with ventriculo-arterial discordance have been excluded from this review. 2. Aortic valve stenosis Generally the problem of borderline left ventricle complicates the decision making process in neonates with critical aortic valve stenosis (Fig. 1). The initial attempts at treating neonates and infants with severe left ventricular outflow tract obstruction have been characterized by elevated mortality in the presence of reduced left ventricular size. In subsequent retrospective studies on the topic, several risk factors have been progressively taken in consideration and found correlated with poor results [3 17]. Left ventricular cross-sectional area!1.6 cm 2, measured with echocardiography, was correlated with very high mortality in infants [3]. Reduced left ventricular end diastolic volume (!80% of normal) and extensive endocardial fibroelastosis with the association of myocardial sinusoids, diagnosed angiographically, and confirmed at autopsy in six over 10 patients, were correlated with mortality in young infants presented within the first two months of life [4]. All deaths have been reported in patients who underwent aortic surgical valvotomy with an indexed left ventricular end diastolic volume!20 ml/m 2 of body surface area [5]. In another study, despite the suggestion to consider a univentricular type of repair for infants with an indexed left ventricular end diastolic volume!20 ml/m 2 of body surface area, the small left ventricular size was not considered a risk factor, reporting no deaths after surgical valvotomy in four neonates with an indexed left ventricular end diastolic volume between 20 and 26 ml/m 2 of body surface area [6]. On the contrary, in the same study risk factors constantly associated with mortality were endocardial fibroelastosis, left ventricular end diastolic pressure O26 mmhg and left ventricular ejection fraction!42% [6]. Other authors reported neonates with critical aortic stenosis who underwent either closed (trans-ventricular) or open surgical aortic valvotomy [7]. Risk factors associated with higher mortality were pre-operative clinical conditions like severe congestive heart failure with hepatomegaly, poor peripheral perfusion with metabolic acidosis (arterial ph on Fig. 1. (A) Echocardiographic four chamber view in a neonate with aortic valve stenosis showing the borderline size of the left ventricular cavity, with end diastolic left ventricular volumez17 ml/m 2 of body surface area. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (B) Angiocardiographic lateral view in the same neonate. aao, ascending aorta; AoS, aortic valve stenosis; LV, left ventricle. admissionz7.3), cardiomegaly on X-ray (cardio-thoracic ratioz0.7) and right ventricular hypertrophy on electrocardiogram (as possible indication of diminished left ventricular volume or mass) [7]. While morphometric parameters associated with hospital mortality were diameter of the mitral valve!11 mm and diameter of the aortic valve!6 mm, functional parameters were left ventricular end diastolic pressure O20 mmhg and left ventricular ejection fraction!40% [7]. Apparently this was the first time that reduced dimension of the left ventricular inflow has been recognized as risk factor for mortality in the surgical treatment of critical aortic stenosis. No survivors have been reported in a group of infants operated on for critical aortic stenosis with indexed left ventricular end diastolic volume!20 ml/m 2 of body surface area, and in addition observed increased hospital mortality in patients with pre-operative mean pulmonary artery pressure O50 mmhg, adding another functional parameter to the list of risk factors [8].

3 A.F. Corno / European Journal of Cardio-thoracic Surgery 27 (2005) Increased hospital mortality was reported also in a clinical comparison between surgical aortic valvotomy and percutaneous balloon valvotomy in neonates with critical aortic stenosis in the presence of reduced left ventricular size [9]. Poor outcome accompanied small (60 80% of normal) and hypoplastic (!60% of normal) left ventricular end diastolic volume [9]. A subsequent study on neonates who underwent open surgical valvotomy for critical aortic stenosis revealed as risk factors the presence of reduced left ventricular end diastolic volume (!60% of normal) and a newly considered morphologic characteristic: the cardiac apex not formed by the left ventricle [10]. In another study, the clinical and echocardiographic data of 20 infants with critical aortic stenosis treated by open surgical valvotomy have been compared with the morphometric data obtained by 20 heart specimens from infants of the same age group [11]. From this study the risk factors associated with poor outcome resulted small mitral valve orifice!9 mm, left ventricular inflow dimensions!25 mm, and diameter of the ventriculo-aortic junction!5 mm[11]. The authors of this study, underlining once more the importance of the dimensions of the left ventricular inflow as prognostic factor in the treatment of severe left ventricular outflow tract obstruction, suggested for this group of patients either cardiac transplantation or univentricular type of repair [11]. Some of the risk factors already reported, namely left ventricular cross-sectional area!2.0 cm 2 and indexed left ventricular end diastolic volume!20 ml/m 2 of body surface area have been associated with all deaths in another study, while left ventricular end diastolic dimension!13 mm was correlated with increased mortality [12]. Once again, based on the conclusion of their observations the authors suggested either cardiac transplantation or uni-ventricular type of repair as the alternative approach for infants with critical aortic stenosis and left ventricle with the above morphometric parameters [12]. A very extensive retrospective analysis has been performed by the Boston group on the echocardiographic data of infants with critical aortic stenosis, mostly treated by percutaneaous balloon dilatation of the aortic valve, and the following parameters resulted correlated with increased risk for hospital death: left ventricular long axis to heart long axis ratio!0.8, indexed aortic root diameter!3.5 cm/m 2 of body surface area, indexed mitral valve area!4.75 cm 2 /m 2, and left ventricular mass index!35 g/m 2 [13]. Based on the results of their multivariate analysis, the authors of the study proposed a score, called afterwards the Score of Rhodes, consisting in the following equation: 14.0 (BSA)C0.943 (iroot)c4.78 (LAR)C0.157 (imva)k12.03, obtained by entering the data of the body surface area (BSA), the indexed aortic root dimension (iroot), the ratio of the long axis dimension of the left ventricular to the long axis dimension of the heart (LAR), and the indexed mitral valve area (imva) [12]. This equation allowed prediction of death after bi-ventricular type of treatment in the presence of a discriminating Score!0.35 [13]. Few years after the publication of this article one of the co-authors (CSD) reported a misprint in the original article of the formula related to the calculation of the mitral valve area, but he ensured that, despite the formula was misprinted, the correct formula was used to obtain the reported core [14]. The attention to a morphological characteristic of the left ventricle, previously presented by another study [4], consisting in the presence of the so-called spongy myocardium, has been underlined as a harbinger of poor outcome [15]. Spongy myocardium can be easily demonstrated on angiographic investigation with left ventriculography [15]. In a clinical report of infants with critical aortic stenosis treated with bi-ventricular type of repair, either by aortic surgical valvotomy or Ross-Konno procedure, morphometric parameters associated with increased hospital mortality were the presence of endocardial fibroelastosis and cardiac apex not formed by the left ventricle, together with a negative Score of Rhodes resulting from the analysis of the left ventricular dimension [16]. This study introduced the very important concept of considering hemodynamic parameters in the decision making process, in particular the observation of the blood flow pattern in the ascending aorta and in the transverse aortic arch. In their retrospective analysis the authors found the presence of total or predominant ante-grade blood flow in the ascending aorta and transverse aortic arch correlated with survival after bi-ventricular type of repair [16]. A prospective multi-institutional clinical study was performed by the Congenital Heart Surgeon Society of North America in neonates with critical aortic stenosis in order to determine factors able to predict the best chance for survival with either a bi-ventricular or a uni-ventricular type of repair [17]. The risk factors for hospital mortality resulting from a multivariable analysis were younger age, presence and degree of endocardial fibroelastosis, left ventricular length and lower z-value of the aortic valve diameter for biventricular type of repair, and presence of moderate or severe tricuspid valve regurgitation and lower diameter of the ascending aorta for uni-ventricular type of repair [17].As a result of this study the Congenital Heart Surgeon Society of North America proposed a Critical Aortic Stenosis Calculator, consisting in a multiple variable equation (available on the net at where after entering the demographic data of the neonate and the morphologic parameters obtained by the pre-operative echocardiographic investigation, the resulting figure predicts for the specific patient the optimal pathway (bi-ventricular or uni-ventricular type of repair) to obtain survival [17]. The main limit of the above multi-institutional study, despite the impressive amount of information and the outstanding analysis, was that in the comparison between bi-ventricular and uni-ventricular type of repair the only surgical approach taken in consideration for bi-ventricular repair was the aortic valvotomy [18]. Other surgical options available in neonates with critical aortic stenosis, like the Ross or Ross-Konno procedures, have not be taken in consideration in the above multi-institutional study, despite previous positive reports [19 23]. In fact the above study could not better recommend the Ross-Konno procedure for neonates with critical aortic stenosis. By normalizing the left ventricular outflow tract dimensions and hemodynamics, and by allowing easy access to the left ventricular myocardium for resection of the endocardial fibroelastosis, this surgical approach addresses three of the most important morphologic

4 70 A.F. Corno / European Journal of Cardio-thoracic Surgery 27 (2005) risk factors correlated with bi-ventricular repair: presence and degree of endocardial fibroelastosis, left ventricular length and lower z-value of the aortic valve diameter [18]. 3. Aortic coarctation with or without hypoplastic aortic arch Another situation where the borderline size of the left ventricle may complicate the decision making is the presence of aortic coarctation with or without hypoplasia of the aortic arch [15,24 29]. When the left ventricle is borderline, the main difference between critical aortic stenosis and aortic coarctation with or without hypoplasia of the aortic arch is the predictable growth of the left ventricle. Provided that adequate relief of the systemic obstruction at the level of the isthmus and aortic arch can be obtained with the surgical treatment, significant growth of the left ventricular dimension has been proven [24 32], even in neonates with indexed left ventricular end diastolic volume is 10 ml/m 2 of body surface area and cardiac apex not formed by the left ventricle [26]. Therefore the morphometric parameters like the score of Rhodes [13] should be used with caution in lesions with systemic obstructions other than critical aortic stenosis, and particularly in the presence of aortic coarctation with or without aortic arch hypoplasia [26 32]. The above observations should be discussed keeping in mind two considerations: the hemodynamic parameters and the presence of an atrial septal defect. With regard to the hemodynamic parameters, the antegrade direction of the blood flow in the ascending aorta, and particularly the presence of bi-directional blood flow at the level of the patent ductus arteriosus characterize the left ventricle with potential for growth, and therefore suitable for bi-ventricular type of repair [30]. These neonates with hypoplastic or borderline left ventricle and aortic coarctation frequently have preoperatively a significant left-to-right shunting at the atrial level, largely due to diastolic dysfunction secondary to the increased after-load. Generally these neonates do not need surgery for the inter-atrial communication, since the defect in most of the cases is a dilated patent foramen ovale that gets smaller in size and eventually closes spontaneously after successful repair of the aortic coarctation [33]. In these neonates the rapid increase in left ventricular size after normalization of the after-load suggest that the left ventricular hypoplasia resulted mostly from the reduced pre-load due to the left-to-right shunting at the atrial level [31]. Even when adequate growth of the left ventricular size is obtained, the early and late outcome in these neonates can be complicated by the diastolic dysfunction of the left ventricle, causing a prolonged adaptation time of the left ventricle, despite an adequate relief of the systemic obstruction. The clinical consequences are lengthy hospitalisation [29], and a late follow-up characterized by a noncompliant left ventricle, with subsequent severe left atrial hypertension and pulmonary hypertension [34]. 4. Hypoplastic left heart complex The nomenclature of hypoplastic left heart complex has been introduced quite recently to indicate a subset of patients at the favourable end of the spectrum of hypoplastic left heart syndrome characterized by hypoplasia of the structures of the left heart-aorta complex, consisting of aortic and mitral valve hypoplasia but without valvular 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 aortic coarctation [35 37]. The pathophysiology in these patients is characterized by the constant presence of antegrade blood flow in the ascending aorta and in the proximal branches of the aortic arch, and the absence of left ventricular fibroelastosis. The growth of the left ventricle in patients with hypoplastic left heart complex has been proved after biventricular type of repair, provided the accomplishment of complete relief of the systemic obstruction [35 39]. The preferred surgical technique is the reconstruction of the ascending aorta and aortic arch using either a pulmonary autograft or homograft. In this situation general agreement does not exists regarding the management of the frequently associated inter-atrial communication. Complete elimination of the left-to-right shunt due to the presence of an atrial septal defect has been suggested to reduce the risk of low cardiac output due to excessive leftto-right shunt through an unrestrictive communication and to improve the left ventricular filling and therefore the subsequent left ventricular growth [37]. Nevertheless complete closure of the inter-atrial communication has been reported with the complications of a stormy postoperative course, with very elevated left atrial pressure particularly during the first h [35]. The elimination of left-to-right shunt at atrial level suddenly forces the entire output through the non-compliant left ventricle, resulting in left ventricular overload and distension. Since the neonatal left ventricle is already functioning at the plateau level of the Starling s curve, any volume overload can determine severe left ventricular dysfunction, and eventually death [38]. An alternative surgical option is the partial closure of the atrial septal defect: a fenestration allows a substantial reduction of the excessive left-to-right shunt in order to improve the left ventricular filling, and in the same time leaves enough time to the left ventricle to adapt to the new loading conditions [38,39]. This surgical approach has been recently utilized in our unit in a neonate with hypoplastic left heart complex with severe aortic coarctation, hypoplastic aortic arch and ascending aorta, large atrial septal defect (diameterz 10 mm), small mitral valve (diameterz6 mm, with tricuspid valve diameterz11 mm) (Fig. 2A) and small left ventricular cavity (14.5 ml/cm 2 of B.S.A.). Only three weeks after a first operation consisting in aortic coarctectomy through left thoracotomy, the left ventricular size increased to reach a volume of 20 ml/cm 2 of BSA, with mitral valve diameterz 16 mm and tricuspid valve diameterz20 mm (Fig. 2B). Because of the severe left-to-right shunt (QP/QsZ3.3)

5 A.F. Corno / European Journal of Cardio-thoracic Surgery 27 (2005) Fig. 2. (A) Echocardiographic four chamber view before aortic coartectomy showing the borderline size of the left ventricular cavity, with diameter of the mitral valvez6 mm and diameter of the tricuspid valvez11 mm. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (B) Echocardiographic four chamber view after aortic coartectomy showing the increased size of the left ventricular cavity, with diameter of the mitral valvez16 mm and diameter of the tricuspid valvez20 mm. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. through the atrial septal septal defect the child remained in heart failure. At cardiac catheterization laboratory a temporary balloon occlusion of the atrial septal defect was accompanied by severe elevation of the end diastolic left ventricular pressure and left atrial pressure up to 45 mmhg. At this point the patient underwent, through median sternotomy and cardiopulmonary bypass, enlargement of the ascending aorta and aortic arch using an autologous patch from the pulmonary artery, with partial closure of the atrial septal defect using a PTFE patch with a central fenestration of 4 mm. The post-operative course was uneventful. 5. Right ventricular pressure and/or volume overload The problem of a borderline left ventricle in the presence of right ventricular pressure and/or volume overload has been reported with several congenital heart defects, particularly total anomalous pulmonary venous connection, unbalanced atrio-ventricular septal defect, and cortriatriatum. Clinical and pathological studies have already addressed long time ago the reduced size of the left ventricle in the presence of total anomalous pulmonary venous connection [40 44]. The left ventricular cavities with reduced size because of the leftward displacement of the interventricular septum have been seen on echocardiographic and angiographic (Fig. 3) investigations [40,42,43] due to the combined pressure volume overload of the right ventricle. Contrasting results from autopsy studies appeared in the literature, with some authors showing a reduced left ventricular size with increased right-to-left ventricular volume ratio in non-survivors after repair [43]. Other investigators observed that, because of the morphometric observation of normal size of the mitral and aortic valves, the left ventricular volume was not decreased despite changes in the ventricular shape [44]. In fact an autopsy examination confirmed the presence of left ventricles with normal mass, despite a reduced size of the aortic valve circumference, interpreted as due to the low left ventricular output probably compromised by the left to right shunt and by the septal displacement [41]. More complex is the problem of evaluating the importance of the size of the left ventricle in patients with atrio-ventricular septal defect. A retrospective study on conventional repair showed the relationship between probability of hospital death and ventricular dominance ratio, with more than 60% mortality in children with complete atrio-ventricular septal defect for a right ventricular dominance with right/left ventricular volumez2.0, and more than 80% mortality for a right/left ventricular volumez2.5 [45]. Because of the above report, alternative surgical options have been considered in the presence of severe right ventricular dominance. The surgical approach we have proposed in the past consisted of a uni-ventricular type of repair: the first palliative stage was a pulmonary artery banding, followed by bi-directional Glenn (endto-side superior vena cava to right pulmonary artery anastomosis) accompanied by modified Damus-Kaye-Stansel (transection of the main pulmonary artery at the bifurcation and end-to-side anastomosis to the ascending aorta) [46]. Fig. 3. Angiographic lateral view in a neonate with total anomalous pulmonary venous connection and borderline left ventricle, with end diastolic left ventricular volumez14 ml/m 2 of body surface area. aao, ascending aorta; dao, descending aorta; LV, left ventricle.

6 72 A.F. Corno / European Journal of Cardio-thoracic Surgery 27 (2005) More recent clinical reports supported the feasibility of biventricular repair in children with complete and partial atrio-ventricular septal defect, even in the presence of unbalanced ventricular morphology, provided that the cardiac apex is formed by the left ventricle [47 49]. An interesting approach to evaluate the suitability of biventricular repair in congenital lesions with right ventricular overload associated with borderline left ventricle has been proposed by the group of San Francisco [50,51]. They hypothesized that the post-operative left ventricular capacity may be better reflected by the pre-operative potential left ventricular volume, calculated as the left ventricular volume if the septal position were normal, without the reverse bowing of the inter-ventricular septum [50,51]. The pre-operative calculation of the potential left ventricular volume is based on a theoretical model of a compressible but otherwise non-compliant left ventricular chamber; while the relative loading states of the right and left ventricle determine the position of the inter-ventricular septum, the right-to-left bowing of the inter-ventricular septum does not induce any change of the endocardial circumference nor of the left ventricular length [50,51]. The hypothesis based on the theoretical model has been confirmed in a clinical study on children with total anomalous pulmonary venous connection, unbalanced atrio-ventricular septal defect with cardiac apex not formed by the left ventricle, and cor triatriatum; the potential left ventricular volume calculated on the pre-operative echocardiographic investigation corresponded very well, or even underestimated, the post-operative left ventricular volume obtained after bi-ventricular repair [50]. Since successful biventricular repair has been accomplished even in patients with pre-operative indexed left ventricular end diastolic volume!15 ml/m 2 of body surface area and cardiac apex not formed by the left ventricle, the authors concluded that in the presence of right ventricular pressure and/or volume overload the small pre-operative left ventricular volume is not primarily due to compression by an overloaded right ventricle, but rather to underfilling: the left ventricle is not hypoplastic, is simply squashed [50]. These clinical observations have been confirmed by our experimental study on chronic hypoxia [52]. While the crosssectional area of the right ventricle in animals exposed to chronic hypoxia was significantly (P!0.001) larger than in normoxic animals (control group), the cross-sectional area of the left ventricle in animals exposed to chronic hypoxia was significantly (P!0.001) smaller than in normoxic animals (control group) [52]. Even more interesting was the observation that the total cross-sectional ventricular area (right plus left ventricle) remained the same in all groups, irrespective of the changes of the separate ventricles [52], confirming that, despite volume and/or pressure overload, the heart maintains its unique morphology [53]. 6. Conclusions This review considers only patients with congenital heart defects with ventriculo-arterial concordance. Our experience in the presence of ventriculo-arterial discordance has been already published recently [54]. Pre-operative determination whether the left ventricle is adequate to sustain the systemic circulation, or it may became adequate with the available surgical approaches, and therefore a bi-ventricular type of repair is feasible, can be extremely difficult, particularly in the presence of a borderline left ventricle. The elements for the decision making process between uni- and bi-ventricular type of repair are the following: morphometric and functional parameters, hemodynamic data, available surgical options, results of the personal and institutional experience. When still in doubt, the following considerations may help in the decision making process: an uni-ventricular type of repair after a failed attempt at a bi-ventricular repair is associated with increased mortality [13], while the opposite seems characterized by better outcome [55] like for the hypoplastic right ventricle, we still don t have the answer to the question Is a high-risk bi-ventricular repair always preferable to conversion to a single ventricle repair? [56] As usually in the decision making process the most important consideration remains that every patient is unique [57]. Acknowledgements Dr Stefano Di Bernardo very kindly provided most of the illustrations used for the preparation of the article. References [1] Collins. English dictionary. Glasgow: Collins Publishers; [2] Kirklin JW, Barrat-Boyes BG. Cardiac Surgery, 3rd ed. London: Churchill Livingstone; [3] Latson LA, Cheatham JP, Gutgesell HP. Relation of the echocardiographic estimate of left ventricular size to mortality in infants with severe left ventricular outflow obstruction. Am J Cardiol 1981;48: [4] Mocellin R, Sauer U, Simon B, Comazzi M, Sebening F, Buhlmeyer K. Reduced left ventricular size and endocardial fibroelastosis as correlates of mortality in newborns and young infants with severe aortic valve stenosis. Pediatr Cardiol 1983;4: [5] Keane JF, Norwood WI, Bernhard WF. Surgery for aortic stenosis in infancy. Circulation 1983;68(Suppl. 3):182. [6] Gundry SR, Behrendt DM. Prognostic factors in valvotomy for critical aortic stenosis in infancy. J Thorac Cardiovasc Surg 1986;92: [7] Pelech AN, Dyck JD, Trusler GA, Williams WG, Olley PM, Rowe RD, Freedom RM. Critical aortic stenosis. Survival and management. J Thorac Cardiovasc Surg 1987;94: [8] Hammon JW, Lupinetti FM, Maples MD, Merrill WH, First WH, Graham TP, Bender HW. Predictors of operative mortality in critical valvular aortic stenosis presenting in infancy. Ann Thorac Surg 1988;4: [9] Zeevi B, Keane JF, Castaneda AR, Perry SB, Lock JE. Neonatal critical valvar aortic stenosis. A comparison of surgical and balloon dilatation therapy. Circulation 1989;80: [10] Karl TR, Sano S, Brawn WJ, Mee RB. Critical aortic stenosis in the first month of life: surgical results in 26 infants. Ann Thorac Surg 1990;50: [11] Leung MP, McKay R, Smith A, Anderson RH, Arnold R. Critical aortic stenosis in early infancy. Anatomic and echocardiographic substrates of successful open valvotomy. J Thorac Cardiovasc Surg 1991;101:

7 A.F. Corno / European Journal of Cardio-thoracic Surgery 27 (2005) [12] Parsons MK, Moreau GA, Graham TP, Johns JA, Boucek RJ. Echocardiographic estimation of critical left ventricular size in infants with isolated aortic valve stenosis. J Am Coll cardiol 1991;18: [13] Rhodes LA, Colan SD, Perry SB, Jonas RA, Sanders SP. Predictors of survival in neonates with critical aortic stenosis. Circulation 1991;84: [14] Colan SD. Correction. Predictors of survival in neonates with critical aortic stenosis. Circulation 1995;92:2005. [15] Freedom RM, Benson LN, Smallhorn JF. Neonatal heart disease. London: Springler; [16] Kovalchin JP, Brook MM, Rosenthal GL, Suda K, Hoffman JIE, Silverman NH. Echocardiographic hemodynamic and morphometric predictors of survival after two-ventricle repair in infants with critical aortic stenosis. J Am Coll Cardiol 1998;32: [17] Lofland GK, McCrindle BW, Williams WG, Blackstone EH, Tchervenkov CI, Sittiwankul R, Jonas RA. Critical aortic stenosis in the neonate: a multiinstitutional study of management, outcomes, and risk factors. J Thorac Cardiovasc Surg 2001;121: [18] Hanley FL. Discussion of: Loland GK, McCrindle BW, Williams WG, Blackstone EH, Tchervenkov CI, Sittiwankul R, Jonas RA, Critical aortic stenosis in the neonate: a multi-institutional study of management, outcomes, and risk factors. J Thorac Cardiovasc Surg 2001;121:25 6. [19] Calhoon JH, Bolton JW. Ross/Konno procedure for critical aortic stenosis in infancy. Ann Thorac Surg 1995;60:S597 S9. [20] Daenen WJ. Repair of complex left ventricular outflow tract obstruction with a pulmonary autograft. J Heart Valve Dis 1995;4: [21] Reddy VM, Rajasinghe HA, Teitel DF, Haas GS, Hanley FL. Aortoventriculoplasty with the pulmonary autograft: the Ross-Konno procedure. J Thorac Cardiovasc Surg 1996;111: [22] Sudow G, Solymar L, Berggren H, Eriksson B, Holmgren D, Gilljam T. Aortic valve replacement with a pulmonary autograft in infants with critical aortic stenosis. J Thorac Cardiovasc Surg 1996;112: [23] Lacour-Gayet F, Sauer H, Ntalakoura K, Müller A, Razek V, Weil J, Haun C. Ross-Konno procedure in neonates: report of three patients. Ann Thorac Surg 2004;77: [24] Page DA, Levine MM. Left ventricular growth in a patient with critical coarctation of the aorta and hypoplastic left ventricle. Pediatr Cardiol 1995;16: [25] Kovalchin JP, Brook MM, Silverman NH. Growth of the hypoplastic left ventricle? Pediatr Cardiol 1997;18: [26] Minich LL, Tani LY, Hawkins JA, Shaddy RE. Possibility of postnatal left ventricular growth in selected infants with non-apex-forming left ventricles. Am Heart J 1997;133: [27] Blaufox AD, Lai WW, Lopez L, Nguyen K, Griepp RB, Parness IA. Survival in neonatal biventricular repair of left-sided cardiac obstructive lesions associated with hypoplastic left ventricle. Am J Cardiol 1998;82: [28] Tani LY, Minich LL, Pagotto LT, Shaddy RE, McGough EC, Hawkins JA. Left heart hypoplasia and neonatal aortic arch obstruction: is the Rhodes left ventricular adequacy score applicable? J Thorac Cardiovasc Surg 1999;118:81 6. [29] Alboliras ET, Mavroudis C, Pahl E, Gidding SS, Backer CL, Rocchini AP. Left ventricular growth in selected hypoplastic left ventricles: outcome after repair of coarctation of aorta. Ann Thorac Surg 1999;68: [30] Tani LY, Minich LL, Hawkins JA, McGough EC, Pagotto LT, Garth SO, Shaddy RE. Spectrum and influence of hypoplasia of the left heart in neonatal aortic coarctation. Cardiol Young 2000;10:90 7. [31] Krauser DG, Rutkowski M, Phoon CKL. Left ventricular volume after correction of isolated aortic coarctation in neonates. Am J Cardiol 2000; 85: [32] Puchalski MD, Williams RV, Hawkins JA, Minich LA, Tani LY. Follow-up of aortic coarctation repair in neonates. J Am Coll Cardiol 2004;44: [33] Graham TP. Discussion of: Alboliras ET, Mavroudis C, Pahl E, Gidding SS, Backer CL, Rocchini AP, Left ventricular growth in selected hypoplastic left ventricles: outcome after repair of coarctation of aorta. Ann Thorac Surg 1999;68:555. [34] Starnes VA. Discussion of: Tani LY, Minich LL, Pagotto LT, Shaddy RE, McGough EC, Hawkins JA, Left heart hypoplasia and neonatal aortic arch obstruction: is the Rhodes left ventricular adequacy score applicable? J Thorac Cardiovasc Surg 1999;118:81 6. [35] Tchervenkov CI, Tahta SA, Jutras LC, Béland MJ. Biventricular repair in neonates with hypoplastic left heart complex. Ann Thorac Surg 1998;66: [36] Tchervenkov CI, Jacobs ML, Tahta SA. Congenital heart surgery nomenclature and database project: hypoplastic left heart syndrome. Ann Thorac Surg 2000;69:S170 S9. [37] Tchervenkov CI. Two-ventricle repair for hypoplastic left heart syndrome. Sem Thorac Cardiovasc Surg Ped Card Surg Ann 2001;4: [38] Serraf A, Piot JD, Bonnet N, Lacour-Gayet F, Touchot A, Bruniaux J, Beli E, Galletti L, Planché C. Biventricular repair approach in ductodependent neonates with hypoplastic but morphologically normal left ventricle. J Am Coll Cardiol 1999;33: [39] Daebritz SH, Tiete AR, Rassoulian D, Roemer U, Kozlik-Feldmann R, Sachweh JS, Netz H, Reichart B. Borderline hypoplastic left heart malformation: Norwood palliation or two-ventricle repair? Thorac Cardiovasc Surg 2002;50: [40] Graham TP, Jarmakani JM, Canent RV. Left heart volume characteristics with a right ventricular volume overload. Total anomalous pulmonary venous connection and large atrial septal defect. Circulation 1972;45: [41] Bove KE, Geiser EA, Meyer RA. The left ventricle in anomalous pulmonary venous return. Morphometric analysis of 36 fatal cases in infancy. Arch Pathol 1975;99: [42] Nakazawa M, Jarmakani JM, Gyepes MT, Prochazka JV, Yabek SM, Marks RA. Pre- and post-operative ventricular function in infants and children with right ventricular volume overload. Circulation 1977;55: [43] Lima CO, Valdes-Cruz LM, Allen HD, Horowitz S, Sahn DJ, Goldberg SJ, Barron JV, Grenadier E. Prognostic value of left ventricular size measured by echocardiography in infants with total anomalous pulmonary venous drainage. Am J Cardiol 1983;51: [44] Rosenquist GC, Kelly JL, Chandra R, Ruckman RN, Galioto FM, Midgley FM, Scott LP. Small left atrium and change in contour of the ventricular septum in total anomalous pulmonary venous connection. A morphometric analysis of 22 infant hearts. Am J Cardiol 1985;55: [45] Studer M, Blackstone EH, Kirklin JW, Pacifico AD, Soto B, Chung GKT, Kirklin JK, Bargeron LM. Determinants of early and late results of repair of atrioventricular septal (canal) defects. J Thorac Cardiovasc Surg 1982;84: [46] Corno AF, Marino B, Catena G, Marcelletti C. Atrioventricular septal defect with severe left ventricular hypoplasia. Staged palliation. J Thorac Cardiovasc Surg 1988;96: [47] Drinkwater DC, Laks H. Unbalanced atrioventricular septal defects. Semin Thorac Cardiovasc Surg 1997;9:21 5. [48] Cohen MS, Rychik J. The small left ventricle: how small is too small for biventricular repair? Semin Thorac Cardiovasc Surg Ped Card Surg Ann 1999;2: [49] Nishimura M, Yamagishi M, Fujiwara K, Yoshida M, Kitamura N. Incomplete atrioventricular septal defect with hypoplastic left ventricle and left atrioventricular valve stenosis. Jpn J Thorac Cardiovasc Surg 2001;49: [50] Phoon CK, Silverman NH. Conditions with right ventricular pressure and volume overload, and a small left ventricle: hypoplastic left ventricle or simply a squashed ventricle? J Am Coll cardiol 1997;30: [51] Van Soon JAM, Phoon CK, Silverman NH, Haas GS. Predicting feasibility of biventricular repair of right-dominant unbalanced atrioventricular canal. Ann Thorac Surg 1997;63: [52] Corno AF, Milano G, Morel S, Tozzi P, Genton CY, Samaja M, von Segesser LK. Hypoxia: unique myocardial morphology. J Thorac Cardiovasc Surg 2004;127: [53] Torrent-Guasp F, Kocica MJ, Corno AF, Komeda M, Cox JL, Flotats A, Ballester-Rodes M, Carreras-Costa F. Systolic ventricular filling. Eur J Cardiothorac Surg 2004;25: [54] Corno AF, Hurni M, Payot M, Sekarski N, Tozzi P, von Segesser LK. Adequate left ventricular preparation allows for arterial switch despite late referral. Cardiol Young 2003;13: [55] Pearl JM, Cripe L, Manning PB. Biventricular repair after Norwood palliation. Ann Thorac Surg 2003;75: [56] Delius RE, Rademecker MA, de Leval MR, Elliott MJ, Stark J. Ia a high-risk biventricular repair always preferable to conversion to a single ventricle repair? J Thorac Cardiovasc Surg 1996;112: [57] Corno AF. Congenital heart defects. Decision making for surgery, Vols. 1 and 2. Darmstad: Steinkopff Verlag; 2003 and 2004.