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a Department of Cardiovascular Surgery, German Heart Centre Munich, Technische Universität München, Munich, Germany
b Department of Paediatric Cardiology and Congenital Heart Disease, German Heart Centre Munich, Technische Universität München, Munich, Germany
Received 13 November 2007; received in revised form 8 May 2008; accepted 28 May 2008.
* Corresponding author. Address: Department of Cardiovascular Surgery, German Heart Centre Munich, Lazarettstrasse 36, D-80636 Munich, Germany. Tel.: +49 89 12 18 4111; fax: +49 89 12 18 4123. (Email: cleuziou{at}dhm.mhn.de).
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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Key Words: Single ventricle • Bidirectional cavopulmonary connection • Infant
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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2.1 Patients
A total of 124 patients received a BCPC followed by an extracardiac TCPC at our institution between 2001 and 2006. Forty patients were excluded from the study because of missing angiograms. From the remaining 84 patients, 28 (33%) were 6 months or less of age at the time of BCPC. They constituted group 1, whereas patients who were older than 6 months of age represented group 2 (n
= 56). Timing of BCPC was decided jointly by paediatric cardiologists and surgeons at their discretion or, if appropriate, depending on clinical features such as decreasing oxygen saturation. During the study period, the policy of our institution changed, and we perform a BCPC now at the age of 3 months and progress to an extracardiac TCPC without fenestration at a body weight of at least 10 kg.
2.2 Operative data
The BCPC was performed through a median sternotomy with normothermic cardiopulmonary bypass in all patients. In 23 patients (27%) the aorta was clamped and the heart arrested with antegrade cold crystalloid cardioplegia for the purpose of additional intracardiac procedures. The remaining 61 patients (73%) were operated on with the heart beating. After extensive preparation of the pulmonary arteries and the superior vena cava (SVC) up to the innominate vein, the SVC was transected at the level of the right atrium and the latter closed with a continuous suture. The azygos vein was ligated and transected in all patients. The SVC was anastomosed to the superior edge of the right pulmonary artery with a 7/0 resorbable running suture in an end-to-side fashion. In cases of bilateral SVC the vessels were anastomosed to both pulmonary arteries, respectively. In all patients, any source of additional pulmonary blood flow was interrupted at the time of BCPC. This included the ligation and take-down of any previous shunt or the closure of the pulmonary valve and transection of the pulmonary trunk, if appropriate. A patch enlargement of the pulmonary artery was performed in 36 patients (43%) at the time of BCPC.
2.3 Review of angiograms
The angiograms of all 84 patients were reviewed by one person. We reviewed one angiogram prior to BCPC and one prior to TCPC. If more than one angiogram had been performed, the one closest to the date of surgery was reviewed for data acquisition. This resulted in a median of 7 days prior to BCPC and 28 days prior to TCPC. The angiogram prior to TCPC was performed at a median time of 15 months after the BCPC. Haemodynamic data collected for analysis comprised the mean pulmonary artery pressure (PAP), the mean atrial pressure, the mean ventricular end-diastolic pressure (VEDP) measured in the dominant ventricle, the mean oxygen saturation, measured either in the aorta or in the dominant ventricle, the pulmonary to systemic blood flow ratio (Q
p/Q
s) and the pulmonary to systemic resistance ratio (R
p/R
s). By means of contrast injection in the dominant ventricle, its function was assessed and described as good, mildly impaired, moderately impaired or severely impaired. The diameter of the pulmonary arteries was measured in millimetres just adjacent to the bifurcation into the pulmonary lobe arteries after injection of contrast through either the native pulmonary artery or a systemic-to-pulmonary artery shunt prior to BCPC. Prior to TCPC, the same measurements were repeated after contrast injection through the BCPC. Z-scores were derived from the normal values described for children with the same body surface area [10].
2.4 Statistical analysis
Descriptive statistics are described as frequencies and percentages for categorical variables and as medians with range or means with standard deviation for continuous variables. Univariate comparisons for categorical variables were examined with the two-tailed 
2-test or, when appropriate, Fischer's exact test. Continuous variables within one group at different times were compared with the Wilcoxon test for two dependent variables. Continuous variables between both groups were compared using the Mann–Whitney test for two independent samples. Statistical significance was defined as p
< 0.05. Statistical analysis was done using SPSS statistical software (Version 15.0.1, SPSS Inc, Chicago, IL).
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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3.2 Postoperative data
No patient died after BCPC. Postoperative morbidity included a temporary hemidiaphragm paralysis in four patients (group 1, n
= 1, group 2, n
= 3, p
= 0.7), a superior vena cava syndrome in four patients (group 1, n
= 3, group 2, n
= 1, p
= 0.1), rhythm disturbances in three patients (all in group 2, p
= 0.5), a pericardial effusion which resolved with oral corticosteroid therapy in two patients (all in group 2, p
= 0.5) and reoperation for bleeding in four patients (group 1, n
= 1, group 2, n
= 3, p
= 0.7). No patient required postoperative insertion of a pleural drain for recurrent effusion or chylothorax. Two patients suffered from postoperative seizures. Two patients required interventional balloon dilatation of the LPA prior to TCPC, one of whom had been 2.3 months old at the time of BCPC. Single ventricle physiology with an extracardiac TCPC without fenestration was completed in all patients at a median time of 17 months after BCPC. Patients from group 1 were younger at the time of TCPC (23 ± 6 months), than patients from group 2 (35 ± 21 months, p
< 0.001). One patient died after TCPC. Patients’ characteristics are depicted in Table 1
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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The BCPC has shown excellent results as an intermediate step towards permanent palliation in functional single ventricles [1–3]. The optimal timing of the BCPC though, remains unclear. Clinical practice usually leads to a decision on the basis of the oxygen saturation or the ventricular function. Improved survival after the Norwood I operation in recent years, was overshadowed by an interstage mortality of more than 10% [6]. Improved monitoring of these patients showed that the oxygen saturation decreases with time after the Norwood I operation and therefore these patients may require an earlier BCPC [8]. Furthermore, in this study, the patients stopped gaining weight after 4 months of age, which suggested that there is no reason to postpone the BCPC to an older age [8]. Assuming that the interstage mortality is caused by an incremental shunt stenosis, an earlier BCPC may contribute to reduce it. Furthermore, knowledge about a steady decrease in oxygen saturation after the Norwood I operation, implies that a planned early BCPC leads to an advantage in survival. Our results show that an early and scheduled BCPC can be performed with good results.
An early BCPC will result in an early volume unloading of the single ventricle, a reduction of the ventricular end-diastolic volume [11] and thus preserve the ventricular function [9]. A reduced systolic ventricular function in patients with single ventricle physiology has been reported in some patients [12] and is associated with a significant late morbidity as well as mortality [13]. Earlier BCPC and thus earlier reduction in end-diastolic volume has shown better outcome in patients below the age of 3 years compared to patients of 10 years and more, who had worse ejection fraction resulting in a bad condition for a successful TCPC [14]. Also, younger age and less time span between BCPC and TCPC is associated with less morbidity after TCPC [15]. In the present study, we could show that haemodynamic performance after BCPC was excellent, even if performed at an early age. However, the benefit of an early unloading of the ventricle on the ventricular function will need re-evaluation in the long-term.
Although excellent results with low morbidity and mortality after the BCPC in patients below the age of 6 months have been reported [9,16], some authors found a higher rate of pulmonary thrombosis [17] and a higher mortality [18,19] in younger patients. In our patient cohort, postoperative morbidity was low and not different between groups. Some concern about low oxygen saturation in the early postoperative period has been stated and is associated with prolonged mechanical ventilation [9,17,20,21]. Although the authors found that the saturations improved until the time of discharge from hospital, this feature might affect the early postoperative morbidity. In the present study, we have occasionally observed low saturations in small infants during the early postoperative period but our data show, that there was no difference in oxygen saturation between patients below and above 6 months of age.
There has been some concern about the pulmonary artery growth after the BCPC. Although there is an increase in pulmonary artery diameter after the BCPC, the z-score comparing the size with a healthy population remains lower than the average [22,23] and stays even low after TCPC [24]. More recent reports show no differences in pulmonary artery sizes at time of TCPC between patients who had undergone BCPC at an earlier age, compared to patients who were older at the time of the BCPC [25]. Our results show, that the PA diameters are lower at any time in younger patients, but there is a significant increase in diameter after the BCPC, thus demonstrating a growth of the PAs. Our institutional policy is to remove all additional pulmonary blood flow at time of BCPC. It is well known that leaving additional pulmonary blood flow will result in a higher oxygen saturation and will shorten the time on ventilation as well as in intensive care unit [21]. But it remains controversial if it also leads to an increase growth of the PAs. Our results show that there is growth of the PAs after the BCPC without additional pulmonary blood flow, even though this growth is not adequate for the body surface area. The smaller size of the LPA can be explained by several factors. The place of an earlier systemic-to-pulmonary artery shunt on the RPA might have resulted in a bigger vessel, a large neoaorta could be narrowing the LPA and thus reducing the blood flow to it and the placement of a unilateral BCPC might also affect a preferential growth of the RPA.
In conclusion, we have shown, that a BCPC can be performed with excellent results even at an age of 6 months or less. Haemodynamic and clinical data demonstrate that the outcome is equal to older patients. For this reason, we will adhere to our current management, which is to opt for an elective BCPC at the age of 3–6 months and plan to complete a single ventricle physiology at a body weight of at least 10 kg. Although the pulmonary arteries grow after the BCPC, they remain too small for the given body surface area. But the sizes of the pulmonary arteries do not influence the clinical outcome. A continued observation of these children throughout childhood is warranted. Because of the presence of increased pulmonary vascular reactivity in very young patients, we would not advise the use of BCPC in patients below the age of 3 months.
4.1 Study limitations
The age of 6 months was chosen arbitrarily. The decision to perform a BCPC at an early age was the physician's preference and might have been dictated by clinical features of the patient such as low oxygen saturation. The retrospective character of this study is a limitation, though the time frame of the operations is quite recent so that a substantial influence due to major changes in perioperative care can be ruled out. We did not look at the duration of hospital stay, neither at the time of mechanical ventilation or of ICU stay, because these factors will not necessary reflect true morbidity.
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Appendix A |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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Dr W. Brawn (Birmingham, United Kingdom): How young can you do a TCP shunt? What's your lower limit?
Dr Cleuziou: The youngest patient in this group was 2.3 months.
Dr Brawn: How low do you go? What's the limit? How do you define the lower limit? Does anybody have any idea?
Dr Cleuziou: We electively do BCPCs now at 3 months of age, but maybe some patients will come earlier. Because of desaturation, I think some patients will come earlier.
Dr Brawn: And do you think that you will remove all interstage deaths by operating at that age, or some will occur before that? When people started doing the Norwood, there was even a query that you could do a CP shunt instead of doing a systemic shunt. It's probably variable from patient to patient, but we have certainly done them at 40 days. On both occasions the CP shunts thrombosed for whatever reason, and it may have been technical, but they thrombosed, and we had then gone back to a systemic shunt and then back to a CP shunt and then back to a systemic shunt, and the patients survived. You know, serendipity. But there must be presumably some cut off point where the benefits outweigh the risks or the risks outweigh the benefits. As you say, probably 3 months or 10 weeks or something like that is probably about right. I just wonder what others feel about that, and yourself, what your experience would be, what you would advise really.
Dr Cleuziou: In the literature some authors stated that below 3 months of age, the pulmonary resistance might be too high.
Dr Brawn: I mean, for instance, would you lower it by introducing nitric oxide in the postoperative period, that sort of thing? Are those tools that one might use if one was concerned about all the benefits of a CP shunt to reduce interstage death? I’m very unclear about this, but it does seem 3 months is okay.
Dr Cleuziou: I think so. We have good results with 3 months.
Dr G. Stellin (Padova, Italy): The ventricular function of malformations with a functional single ventricle, ‘which needs to support both the pulmonary and systemic circulations’ especially the diastolic function, has always been a concern in the long term. I wonder if you have studied how the ventricular function is, in the long term, in the 2 categories of patients, those ones in which you have done the unloading procedure before the 6 months and those ones in which you have done the unloading procedure afterwards.
Dr Cleuziou: Well, this current investigation is going on. But there was no difference in the short time period until TCPC, until completion, for the ventricular function in both groups. Obviously we will have to review these patients also after TCPC, after completion of Fontan to see how they will do in the long term.
Dr Stellin: I understand that, but you haven’t found any difference between those you have done the unloading procedure before the age of 6 months as compared to those where you have done the unloading procedure afterwards?
Dr Cleuziou: No.
Dr Stellin: Your conclusions are in opposition to the data that we published about 5 years ago in our institution where we found a major difference in the population of patients where we have performed our unloading procedure earlier, with the aim of preserving the ventricular function in the long term.
Dr C. Brizard (Melbourne, Australia): I would like to tell about our experience in Melbourne in answer to Bill Brawn's comment. For the last seven years we have done BCPS for Norwoods at 3 months on the dot, and we have done it earlier when there are signs of cardiac failure, tricuspid regurgitations, and we can do that down to 2 months. We are even thinking of doing it earlier. We often combine an early BCPS with a tricuspid valve repair. It's not for desaturation but for cardiac failure that we do that. The patient can be very desaturated for the first 2 or 3 days after the surgery, but they have very good output and show no lactacidemia and a very good tolerance to that.
Dr Cleuziou: Yes, we have noted as well that some very tiny patients might be more desaturated in the first days after a BCPC, although in this study it did not come out as a significant difference.
Dr Brizard: But it rises quite rapidly after 2 or 3 days.
Dr Tsang: Can I just confirm one thing you just said. You would do your cavopulmonary shunt at 3 months of age, not because of circumstances but because you believe it is physiologically superior?
Dr Brizard: It is our policy first to reduce the interstage mortality as much as possible but also to unload the ventricle. We think that with hypoplastic left heart syndrome, the right ventricle has a different composition and that we should make every effort to reduce the volume loading as early as possible.
Dr J. Amato (Chicago, Illinois, USA): Several years ago Frank Hanley's group presented a paper entitled ‘Pulmonary artery growth after bidirectional cavopulmonary shunt: is there a cause for concern?’. The article stated that in younger children whose antegrade blood flow was cut off that the size of the pulmonary arteries diminished. This lack of additional flow could cause lack of growth of these arteries. While the short-term conclusions were favourable, there was a question as to whether a long-term palliation or going to a Fontan repair should be delayed in order to allow further growth of pulmonary arteries. He stated that it would not be feasible to go ahead and do a bidirectional at this young age and that he would wait.
Dr Cleuziou: Because of?
Dr Amato: Decrease of blood flow, not enough blood flow to cause pulmonary growth.
Dr Cleuziou: Well, there is growth in the pulmonary arteries, and Dr Schreiber will talk about it in the next talk, and in both groups, also in the younger patients. But pulmonary arteries stay below the average population anyway after BCPC, and although the pulmonary arteries remain smaller than the average, we have seen that it does not have any clinical impact on these patients. They still do well, although the pulmonary arteries might not be as big as the average. They are big enough, I suppose.
Dr J. Pajak (Katowice, Poland): Do you use any special pharmacological support for these younger patients?
Dr Cleuziou: No, not on a routine basis. It depends on the clinical findings.
Dr Tsang: You mean on the intensive care unit?
Dr Pajak: Yes, right.
Dr Cleuziou: Well, we won’t put them all on nitric oxide; only if we feel that they will need it, but not on a routine standard basis.
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Footnotes |
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Presented at the 21st Annual Meeting of the European Association for Cardio-thoracic Surgery, Geneva, Switzerland, September 16–19, 2007. |
References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionAppendix AReferences |
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