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J Thorac Cardiovasc Surg 2001;122:1199-1207
© 2001 The American Association for Thoracic Surgery
Surgery for Congenital Heart Disease (CHD) |
From the Department of Pediatric Cardiac Surgery: Marie-Lannelongue Hospital, Le Plessis-Robinson, France
Received for publication May 14, 2001. Revisions requested June 22, 2001; revisions received July 24, 2001. Accepted for publication July 27, 2001. Address for reprints: Alain Serraf, MD, Department of Pediatric Cardiac Surgery, Marie-Lannelongue Hospital, 133 avenue de la Résistance, 92350, Le Plessis-Robinson, France (E-mail: aserraf{at}ccml.com).
Abstract
Background: It is well established that the arterial switch operation is the surgical procedure of choice in patients with transposition of the great arteries and balanced ventricular anatomy. The surgical approach of choice in patients with transposition but unbalanced ventricular size is unknown.
Objectives: Since the beginning of the arterial switch operation program, patients with transposition of the great arteries and unbalanced ventricles underwent biventricular repair by means of the arterial switch operation and repair of any associated lesions, either through a single or staged surgical procedure. The aim of this retrospective study is to analyze whether this approach can be proposed to such patients.
Methods: Forty-four patients with transposition of the great arteries and unbalanced ventricles underwent this surgical approach since 1984. Two groups were defined: group I had transposition with a dominant right ventricle (n = 28), and group II had transposition with a dominant left ventricle (n = 16). In group I the median age and weight at the arterial switch operation were 8.5 days (range, 5-70 days) and 3.1 kg (range, 1.5-3.7 kg), respectively. The median end-diastolic left ventricular volume, mass, and long-axis ratio were 15 mL/m2 (range, 11-16 mL/m2), 31.5 g/m2 (range, 20-66 g/m2), and 0.85 (range, 0.9-0.7), respectively. The mitral valve diameter was slightly hypoplastic, with a median z value of –1.22 (range, –0.3 to 3.7). In group 2 the median age and weight at the arterial switch operation were 42 days (range, 8 days–15 years) and 3.5 kg (range, 2.8-35 kg), respectively. Associated lesions in this group were coarctation in 9 and single (n = 12) or multiple (n = 4) ventricular septal defects. The median long-axis ratio and tricuspid z value were 0.6 (range, 0.3-0.8) and –0.9 (range, –0.5 to 3.3), respectively. In this group 9 patients had a single-stage procedure with fenestrated ventricular defect patches, atrial septal defect patches, or both; 7 patients underwent the staged approach.
Results: In group I there was 1 early death from sepsis after weaning from postoperative extracorporeal membrane oxygenation. Three patients had severe pulmonary hypertension, one of whom died 1 year later. All survivors demonstrated, at discharge from the hospital, equilibrated ventricular size, with a median left ventricular end-diastolic volume of 25 mL/m2 (range, 21-30 mL/m2). In group II there were 2 early and 1 late deaths. All early deaths occurred in patients without voluntary residual intracardiac shunts. Median early postoperative long-axis ratio and tricuspid z value were 0.8 (range, 0.7-1) and –0.2 (range, 0.74 to 1.2), respectively.
Conclusion: This study demonstrates that the arterial switch operation in patients with transposition of the great arteries and unbalanced ventricles remains a good surgical option.
Prenatal structural anomalies, physiologic anomalies, or both can lead to underdevelopment of a ventricular cavity.
1 Irrespective of whether the degree of hypoplasia of a ventricular cavity is amenable to biventricular repair remains a focus of controversy. The approach that considers univentricular repair in high-risk patients has been proved to result in good early- and medium-term results in terms of survival and quality of life. 2 Although the length of follow-up is increasing in these patients undergoing such an approach, questions remain with regard to long-term survival and quality of life. Indeed, several studies have shown that long-term survival after a univentricular heart repair comprises an attrition rate that is not nul. 3 Although the surgical modifications for completion of a univentricular heart repair introduced by Puga, 4 de Leval, 5 Amodeo, 6 and their coworkers seem to improve the immediate outcome, it is still too early to draw conclusions regarding long-term outcome. On the other hand, biventricular repair can restore near-normal anatomy and physiology. Previous works have shown that a ventricle can grow provided there is adequate hemodynamic triggering signal and anatomy. We have demonstrated that a small left ventricle can grow after a surgical approach that should not be too aggressive (ie, long crossclamp and bypass times that presume an additional ischemic injury to a previously compromised ventricle). 7 We proposed a staged approach that will progressively remodel the hypoplastic ventricle until definitive repair. Finally, the degree of ventricular hypoplasia was not as important as the anatomy of the inlet and outlet of the ventricle, and ideally this approach will provide satisfactory results in terms of survival and function for the biventricular repair. However, there remains a certain group of patients with a hypoplastic ventricular cavity, either the right or the left, that cannot be treated with a simple surgical approach, and therefore the operative risk should be higher. In addition, delaying complete repair beyond the neonatal period might potentially alter or slow down the possibility of ventricular remodeling.
In this work we reviewed our experience in patients born with transposition of the great arteries (TGA) and unbalanced ventricles, either a hypoplastic right or left ventricle, for whom univentricular or biventricular repair was discussed and who finally underwent biventricular repair. In all cases of a hypoplastic left ventricle, a distinction was made between a de-prepaired left ventricle, which is beyond the topic of this work.
Methods
Since the beginning of the arterial switch operation (ASO) program in 1983 for TGA, among more than 1200 patients, 44 (3.6%) consecutive patients had hypoplasia of either the right or left ventricle. In these patients the degree of ventricular hypoplasia was important enough to discuss either single or double ventricular repair, but ultimately the patients underwent a biventricular repair that comprised an ASO associated with repair of any associated defects through a single or staged procedure. During the same period, no patients with the same anatomy, physiology, or both, underwent another type of operation.
All the patients underwent a thorough echocardiographic assessment, including anatomic description, functional evaluation, and comparison with a matched cohort of patients with TGA and balanced ventricular anatomy.
Assessment of left ventricular hypoplasia
Aortic anulus size and aortic root were measured from a parasternal long-axis view. Dimensions of the transverse arch and of the aortic isthmus were obtained from suprasternal images. The mitral valve anteroposterior diameter was obtained from the parasternal long-axis view, and the lateral diameter was obtained from the apical 4-chamber views at end-diastole. Left ventricular volumes were calculated with the biplane model and subcostal long- and short-axis views. The long-axis ratio (LAR) was determined from the apical 4-chamber view by dividing the long axis of the left ventricle by the long axis of the heart. All the measurements were indexed to body surface area (BSA). Left ventricular end-diastolic and end-systolic endocardial diameters were taken from TM images at the midportion of the left ventricle.
Myocardial mass and posterior parietal and septal thicknesses were recorded and indexed to BSA to distinguish between hypoplastic and deprepaired left ventricles. The mass/volume ratio was used to indicate the ability of the left ventricle to sustain systemic cardiac output in the postoperative period if superior to 1.2. At less than this value, the primary ASO is believed to be uncertain because of insufficient left ventricular muscular mass to assume postoperative systemic output.
The observed measurements were standardized to z values by the following equation 8:
z = Logarithm (Observed dimension) – Logarithm (Mean normal dimension)/ SD of the mean normal dimension,
where the normal dimensions were obtained from previously published works normalized to BSA. 9-11
A left ventricle was considered hypoplastic if the following 2 criteria were fulfilled: left ventricular end-diastolic volume of less than 20 mL/m2 and mass/volume ratio of greater than 1.2. Other nonexclusive criteria were also recorded, such as LAR of less than 0.8 and z score of less than –1 for mitral valve diameter.
Assessment of right ventricular hypoplasia
The right ventricular outflow tract was measured from a parasternal short-axis view. The size and anatomy of the pulmonary artery branches were obtained from suprasternal and subcostal views. The lateral diameter of the tricuspid valve was evaluated through an apical 4-chamber view at end-diastole. The LAR was determined from the apical 4-chamber view by dividing the long axis of the right ventricle by the long axis of the heart. Straddling and overriding tricuspid valves were also noted.
The observed measurements were also standardized to z values according to the same formula as for the left side of the heart.
A right ventricle was considered hypoplastic if the LAR was less than 0.8 associated with another nonexclusive criteria, namely a z value of the tricuspid valve diameter of less than –1. The latter criteria was nonexclusive because we encountered cases of a hypoplastic right ventricle with normal but overriding, straddling, or both of the tricuspid valve diameter. In these cases of a hypoplastic right ventricle, it was generally tripartite.
Patients
Patient data are given in Table 1. There were 15 female and 29 male patients. Hypoplasia of the left ventricle (group 1) was present in 28 patients, and hypoplasia of the right ventricle (group 2) was present in 16 patients. The median weight at the time of the operation was 3.1 kg (range 1.5-3.4 kg) in group 1 and 3.5 kg (range, 2.6-35 kg) in group 2. The median ages were 8.5 days (range, 4-46 days) and 42 days (ranges, 8 days-3.6 years), respectively.
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Follow-up and statistics
Follow-up was achieved in the case of all survivors by means of telephone contact with the patient's family and the referring cardiologist. Control echocardiographic studies were performed before discharge and at regular intervals after the operation. The size of the ventricular cavities was noted and analyzed according to the same criteria. Comparisons between preoperative and postoperative sizes of the echocardiographic indices were performed with the paired Student t test. Actuarial survival curves and freedom from reoperation were constructed according to Kaplan-Meier methods.
Results
Mortality
There were 3 early deaths, 1 in group I and 2 in group II. In group 1 the patient who died postoperatively presented with an EDLVV of 12.4 mL/m2 and a mass/volume ratio of 2.6. Coronary anatomy was normal, and he was born with a very restrictive ASD of 2 mm. After a standard ASO procedure, weaning from cardiopulmonary bypass was impossible because of the inability of the left ventricle to assume a systemic output. After 3 days of extracorporeal membrane oxygenation, he could be weaned with a satisfactory cardiac output but unfortunately died 2 days later of fulminant bronchopulmonary sepsis. In group 2 the 2 patients who died had no voluntary residual intracardiac shunt at the time of the operation and experienced right-sided heart failure.
Postoperative course
Group I was marked by the necessity to use more intropic agents than usual. Three patients had severe pulmonary hypertensive crises during the early postoperative course that were controlled by inhalation of nitric oxide. There was a trend in this group toward more elevated left atrial pressure and diastolic dysfunction demonstrated at early postoperative echocardiography.
The same was true in group II with regard to inotropic drugs. Most of the patients with residual shunt demonstrated right-to-left shunting during this period; however, arterial oxygen saturation was never below 85%. Two patients from this group required a permanent pacemaker for complete AV block.
Late mortality
There were 2 late deaths, 1 in each group. One patient from group I had severe pulmonary hypertension during the follow-up. Catheterization demonstrated suprasystemic pulmonary hypertension without any anatomic causes. He was treated with a prostaglandin I2 analog but died 1 year later. Another patient from group II had repair at 3 months of age with a fenestrated VSD patch. Although the right ventricle demonstrated satisfactory growth and function, 18 months later, he had acute tricuspid endocarditis with severe regurgitation. He was reoperated on because of uncontrolled sepsis and died 4 days after reoperation.
Growth of the hypoplastic ventricular cavity
Data on growth of the hyoplastic ventricular cavity is presented in Table 2 and Figures 1
and 2. In group I at discharge all the surviving patients demonstrated harmonious and satisfactory growth of the left ventricle. The median EDLVV, LAR, and mitral diameter z values were 25 mL/m2 (range, 17-30 mL/m2), 1 (range, 0.9-1.3), and –0.4 (range, –0.8 to 1.2), respectively (P < .05).
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Follow-up and reoperation
A median follow-up of 62 months (range, 7-180 months) was achieved in all the survivors, and none was lost to follow-up.
In group I, with a preoperative dominant right ventricle, persistent pulmonary hypertension was diagnosed by means of echocardiography in 3 patients. In 2 of these patients, pulmonary arterial pressures returned to normal within 6 months postoperatively, whereas in 1 patient they became suprasystemic, and this patient died 1 year postoperatively. There was no other morbid event in the remaining patients from this group. At the last follow-up, they were all in New York Heart Association class I, with normal sinus rhythm, normal sizes, and normal functions of the right and left ventricles without any medication.
In group II, 2 patients required a reoperation within a median of 24 months (range, 18-36 months). One previously described patient with a fenestrated VSD patch had tricuspid valve endocarditis with severe valve incompetence and right-sided heart failure. Because of overwhelming sepsis, he was reoperated on for tricuspid valvuloplasty and VSD fenestration closure. Although postoperative follow-up echocardiography demonstrated a satisfactory repair, right ventricular function continued to deteriorate, and he died 4 days after the reoperation. Another patient with TGA, small VSD, and coarctation underwent single-stage repair by means of ASO and coarctation repair with a pulmonary homograft. Two years later, recoarctation developed with calcifications of the homograft. After an unsuccessful balloon angioplasty, he was reoperated on and underwent an end-to-end anastomosis. Among the other survivors, 1 had a very slow recovery of biventricular function with a suboptimal growth of the right ventricle and was still receiving converting enzyme inhibitors at 3 years postoperatively. At the last follow-up, the remaining survivors were free of symptoms, with a peripheral arterial oxygen saturation of 100% without any medication and without evidence of residual intracardiac shunt.
The overall actuarial survival at 10 years was 87% ± 6%. It was 91% ± 6% for group I and 79% ± 12% for group II (P = not significant; Figure 3).
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This retrospective work tends to prove that even in a context of a hypoplastic ventricular cavity with TGA, surgical repair by means of reestablishing near-normal biventricular anatomy and physiology can be a signal for growth of the same cavity. In a previous work 7 we showed that a hypoplastic left ventricle or so-called class 3 hypoplastic left heart syndrome of Kirklin's classification 12 is amenable to biventricular repair through multiple staged operative procedures. In this previous work we proposed that a step-by-step surgical approach was able to induce growth of the small left ventricle without major risk. The present study demonstrates that even with major surgical procedure with long aortic crossclamp and cardiopulmonary bypass times, the postoperative left ventricular suitability to sustain a systemic output, as well as to grow, is not impaired. Moreover, this function is ideally long lasting in the majority of the cases.
For a hypoplastic right ventricle, the situation seems to be different. Indeed, experience with biventricular repair of pulmonary atresia, an intact ventricular septum, and a small right ventricle showed that biventricular heart repair is achievable through multiple procedures and that restoration of normal right ventricular size and function takes longer than for the left ventricle. 13 Early complete repair through a single-stage procedure is believed to be very dangerous in this setting because of the small size of the tricuspid valve and the poor compliance of the right ventricle. In patients with TGA and a hypoplastic right ventricle, there is a spectrum of associated malformations, mainly single or multiple VSDs and coarctation. Although the size of the tricuspid valve might be normal, it is generally below the normalized size relative to the BSA and to the right ventricular outflow tract size. The surgical approach to achieve a biventricular repair is less standard than that for patients with a hypoplastic left ventricle. We believe it is important to restore near-normal blood flow through the inlet and outlet of the right and left ventricles; however, because compliance is impaired either by an acute volume overloading or by a large synthetic patch for VSD closure and ventricular size, a residual shunt is left patent. The 2 early postoperative deaths in this group had no residual shunt. Whether to leave an atrial or ventricular shunt is indicated according to the inflow or outflow sizes of the right ventricle. When there is an inflow restriction with a small tricuspid valve, the residual shunt is at the atrial level, and when the inflow is near normal, it is left at the ventricular level. At this stage there is no indication for one-and-a-half ventricle repair because (1) the procedure is generally performed before the time at which a bidirectional Glenn anastomosis is advocated and (2) residual intracardiac shunting might have the same physiologic loading effects as a Glenn anastomosis. Also, it was demonstrated that growth of the right ventricle is more time related and that as the shunt decreases size, function of the ventricle improves. Indeed, in this group of patients, either single or multiple staged procedures gave satisfactory results. All but 1 patient that had previous palliation demonstrated adequate size and function of the right ventricle at the time of the ASO. Of interest was 1 patient who was believed to be a poor candidate for biventricular repair because of severe straddling of the tricuspid valve through a large inlet VSD. He had pulmonary artery banding early after birth, followed 2 years later by a bidirectional Glenn anastomosis. Because intracardiac anatomy was not repaired, the right ventricle did not demonstrate any particular growth and remained in the lower ranges in size. He could, however, have undergone a one-and-a-half ventricle repair by means of intracardiac repair and an ASO at 6 years of age. Indications for one-and-a-half ventricle repair are therefore limited to an inadequate growth, function, or both, of the right ventricle with persistent right-to-left shunting. Leaving a residual intracardiac shunt has already been used in several surgical situations, either univentricular or biventricular repairs. 14,15 It is generally well tolerated in the immediate postoperative period and presents a tendency to spontaneously close. In the present series none of the patients had to be reoperated on for closure of the residual shunt.
From the present study, it was difficult to define parameters that could ascertain that biventricular repair could be safely performed. The failures encountered were mainly the result of a surgical problem rather than a surgical indication. Previous studies 13,16-19 have tried to set critical values that may help in decision making for univentricular or biventricular repair in different clinical situations, namely AV septal defect with unbalanced ventricles or critical aortic stenosis and a hypoplastic left ventricle. Although these values may be of some help, in our experience failures after biventricular repair were more correlated to surgical techniques than to inappropriate indications. In addition, AV septal defects and unbalanced ventricles present severe defects in heart architecture, which is not the case in TGA. In the setting of critical aortic stenosis and a hypoplastic left ventricle, the defined criteria, particularly those defined by Rhodes, 18 Lofland, 19 and their colleagues, are not truly applicable to the model of TGA because the left ventricle, although small, is not submitted to the same loading conditions, namely increased afterload in critical aortic stenosis caused by an anatomic lesion. In contrast, in TGA with a small left ventricle, we assumed that pulmonary vascular resistance was higher than usual, but still the patient was not profoundly desaturated, meaning that there was an acceptable transpulmonary output. Ultimately, we disregarded these criteria. 7
Mechanisms through which the ventricle grows are unknown. We have no data supporting either a hypertrophic status, hyperplastic status, or both, of the muscular mass, and only morphometric cellular studies can provide such data. It is more likely that the ventricles, when adequately loaded, elongate and reach normal values that are probably similar to those of the observed growth of the pulmonary arteries after surgical correction of a tetralogy of Fallot.
The reason that the ventricular cavity is underdeveloped is probably different, according to the right or left side. In case of a hypoplastic right ventricle, either the inflow or the outlow of the ventricle is restricted, and therefore the limited forward flow cannot promote sufficient growth of the ventricle. 7 In some cases although the inflow or the outflow looks normal in size, the direction of the forward flow is abnormal because of an overriding tricuspid valve, straddling tricuspid valve, or both. Finally, in the context of TGA, VSD, and coarctation, it has been reported that the right ventricle is associated with hypoplasia of the inlet part of the right ventricle. 20
Hypoplasia of the left ventricle with TGA does not seem to rely on anatomic or rheologic factors. The forward flow through the mitral valve, as well as the sizes of ASD and the ductus, were not different from those of patients with TGA and a normal left ventricle. In addition, the sizes of mitral and pulmonary valves were not severely hypoplastic. All the patients included in this series had well-prepared left ventricles for primary ASO, as defined in our institution, and the postoperative course confirmed these preoperative data.
Altogether, this study demonstrates that in patients with complex heart defects associated with hypoplasia of a ventricular cavity, a biventricular repair is feasible with acceptable results in a single-stage operation provided that anticipation of poor postoperative ventricular compliance is addressed. The mechanism by which a ventricle is hypoplastic in this subset of patients is probably different for the right and the left ventricles. Hypoplasia of the right ventricle seems more to rely on anatomic and rheologic factors, whereas hypoplasia of the left ventricle might be related to a molecular mechanism. We were not able, in this study, to define a minimal value below which a biventricular repair is contraindicated, irrespective of the interested ventricle, and the decision as to whether to perform a biventricular repair is more appreciated by the global aspect of the ventricular anatomy. General principles, as previously published, 7 namely postoperative unobstructed ventricular inlet and outlet, seem to be more important than the total myocardial mass and volume. However, concern about the postoperative ventricular function is major, and either atrial or ventricular fenestration might be absolutely required, particularly for a hypoplastic right ventricle.
In conclusion, biventricular repair can be safely performed in patients with TGA and unbalanced ventricles, and this approach is, to our mind, a good alternative to physiologic repair.
Appendix: Discussion
Dr Ivan M. Rebeyka (Edmonton, Alberta, Canada). This presentation represents yet another important contribution from Marie Lannelongue Hospital to the management of infants born with transposition anatomy.
The authors have addressed the dilemma we all regularly face in deciding whether an individual patient is best suited for biventricular repair, a dilemma that extends beyond transposition to a number of other lesions. Despite the sacrifice in functional reserve and concern over long-term survival associated with single-ventricle repair, the ongoing evolution of the Fontan procedure resulting in low single-digit mortality rates achieved on a consistent basis has only served to make these decisions more complicated. It is not sufficient to simply classify a particular patient's anatomy as being potentially amenable to biventricular repair; rather, we are forced into an attempt at determining the relative risk involved compared with the high likelihood of ultimately obtaining a successful Fontan outcome.
Long before z values became fashionable, my mentor, George Trusler, had surmised that a biventricular repair carried a prohibitive risk when the AV valve orifice diameter measured intraoperatively was less than two thirds of normal. If one carefully looks at valve size nomograms, one will find that a diameter of two thirds of normal corresponds surprisingly close to a z value of –4. Thus, it was of little surprise when, in 1996, Cohen and colleagues from Children's Hospital of Philadelphia reported their algorithm for the management of unbalanced atrioventricular septal defect, showing patients with an AV valve index of greater than 0.67 could uniformly undergo biventricular repair. As potentially useful as this rough rule of thumb might be, most of us would feel more comfortable with planning our operative strategy preoperatively by using objective criteria rather than relying on a decision made on the spot while standing under the lights. Furthermore, previous studies have emphasized the large degree of overlap when single parameters were used to distinguish successful versus failed attempts at biventricular repair. Despite its limitations, this explains the popularity of calculating the so-called Rhodes score for critical aortic stenosis.
The strength of this study relates primarily to the authors' credibility in analyzing the results of the ASO on the basis of a vast experience of over 1200 patients spanning almost 2 decades. Despite the overall volume of ASO operations performed at this institution, there are limitations in this study when one attempts to derive a clear message from the data. With relatively few deaths and overall sample sizes of 28 and 16 for hypoplastic left and right ventricles, respectively, meaningful statistical analysis becomes difficult.
The fundamental issue remains that the degree of hypoplasia is a continuous spectrum, yet we are forced into a position of making a black-and-white decision regarding single- versus 2-ventricle repair on the basis of an interpretation of varying shades of gray.
My questions are as follows:
Dr Serraf: Thank you, Dr Rebeyka, for your comments and questions.
Your first question concerned the decision to fenestrate an ASD or VSD and whether it was made before or during the operation. We try to adopt a strategy that everything is clear before the operation. And in these patients we made the decision before the operation to fenestrate the patient.
Now, fenestration at the atrial level or at the ventricular level depends on the size of the tricuspid valve. I did not mention this in the presentation, but some of the patients might have a near-normal tricuspid valve size, with the right ventricle still hypoplastic because of an overriding or a straddling valve. Therefore, if we had a small tricuspid valve, a hypoplastic tricuspid valve, we will fenestrate at the atrial level. If the tricuspid valve seems to be near the normal size, we will fenestrate at the ventricular level.
Your second question concerned 2 patients who died without fenestration. We do not know whether fenestration is crucial for those patients, but looking back to this series, we do not want to leave a patient without fenestration. The numbers are too small to draw statistical significance. Moreover, in the long-term follow-up, all the shunts are closing alone without any intervention.
Your third question concerned those patients with a staged approach in hypoplasia of the right ventricle. As we mentioned in the second slide, there are 2 signals for growth of the ventricle. One signal is an anatomic signal, that is, an obstructed inlet and outlet of the ventricle. The other signal is a hemodynamic signal, and we believe that the importance of the hemodynamic signal is achieved by means of palliation, namely repair of a coarctation and even a band can restore a near-normal preload of the ventricle and the near-normal afterload of that ventricle. I believe that this is one of the signals that may induce the growth of that ventricle after a staged palliation. We do not have any algorithm to propose because the numbers are small. This is our approach in that group of patients.
Your last question concerned the limits of this approach. I would return to you what Dr Trusler said, that two thirds of a valve is, as you said, a z score of –4. I think that we can apply this operation for AV valves at –4. We are not looking in our institution at the muscular mass. We are looking at the rigid structure, namely the AV valve and the arterial valve. Therefore, –4 for the AV valve should be a limit, but maybe we can go further.
Dr John E. Foker (Minneapolis, Minn). I would like to congratulate the authors for advancing the cause of biventricular repairs. To keep this brief, I would like to ask one question and then make a comment on the limits of this approach.
Were the studies that you made, your volume and mass estimates, done on a biplane evaluation or a single plane, such as M mode? The reason I think that is important in terms of getting everybody on the same page for determining the limits is that the single-plane determinations give you very low values, falsely low values. You cannot draw the line sharply as to the limit of an adequate ventricle. But on the left side, certainly, when you get down around a z score of –3.5 to –4 or a volume of 13 to 15 mL/m2, that's going to be at the borderline of an adequate or inadequate ventricle.
Now, you will find some that are beyond that. We have had 2 that had z values of –6, –6.8, and in that range they would have an index volume of about 10 mL/m2. Therefore, what we would do for those is to not just establish a normal preload but to make an extra preload by restricting, as a first stage, the ASD, putting in a shunt, and, depending on the situation, banding them. These 2 both had bands. You find that the ventricles will grow. I would take some issue with remodeling. I think it is a normal growth, up to the normal range, in a very short period of time. It is 2 or 3 weeks, and then one can go ahead with a biventricular repair with more confidence because the issue is where is it going to succeed and where it is going to fail.
Dr Gian Carlo Crupi (Bergamo, Italy). Could you please expand on your root access for closure of the VSD, particularly in the presence of a quite hypoplastic tricuspid valve and particularly in the patient of yours who had multiple VSDs.
Finally, do you think that the given type of VSD, let us say a posterior VSD, can be a contraindication for biventricular repair?
Dr Serraf: Thank you for your question, Dr Crupi.
Almost all the VSDs in this group of patients are closed through the native pulmonary arteries, and we have a very good access on, I would say, two thirds of the septum through these native pulmonary valves.
For the apical VSDs or other VSDs that are not closable through this approach or through the tricuspid valve, we will do a small ventriculotomy in this patient. Apical VSDs are approached by a very small right apical ventriculotomy.
Footnotes
Read at the Eighty-first Annual Meeting of The American Association for Thoracic Surgery, San Diego, Calif, May 6-9, 2001. 
References
This article has been cited by other articles:
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 R. Formigari, R. M. Di Donato, G. Gargiulo, D. Di Carlo, C. Feltri, F. M. Picchio, and B. Marino Better surgical prognosis for patients with complete atrioventricular septal defect and Down's syndrome Ann. Thorac. Surg., August 1, 2004; 78(2): 666 - 672. [Abstract] [Full Text] [PDF]
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