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Influence of Pulmonary Artery Size on Early Outcome After the Fontan Operation
ORIGINAL ARTICLES: CONGENITAL HEART SURGERY
CONGENITAL HEART SURGERY: The Annals of Thoracic Surgery CME Program is located online at http://www.annalsthoracicsurgery.org/cme/ home. To take the CME activity related to this article, you must have either an STS member or an individual non-member subscription to the journal.
Anja Lehner, MD, Anna Schuh, MS, Florian E. M. Herrmann, MS, Martin Riester, MD, Sabine Pallivathukal, MD, Robert Dalla-Pozza, MD, PhD, Rainer Kozlik-Feldmann, MD, PhD, Heinrich Netz, MD, PhD, Edward Malec, MD, PhD, and Katarzyna Januszewska, MD, PhD Department of Pediatric Cardiology and Pediatric Intensive Care, University Hospital Munich, Ludwig Maximilian University, Munich, Germany; and Department of Cardiothoracic Surgery, Division of Pediatric Cardiac Surgery, University Hospital Muenster, WestfalianWilhelm’s-University, Muenster, Germany
Background. Small pulmonary arteries (PAs) are often considered as a contraindication for the Fontan operation (FO). The aim of this study was to evaluate if the PA size is still one of the major impact factors on the postoperative early outcome. Methods. Data of 146 patients, with a median age of 2.0 years (range, 1.5 to 18 years) and a median weight of 12.45 kg (range, 7.7 to 64.7 kg) who underwent a modified FO in the same center between 2007 and 2012 were retrospectively analyzed with respect to the traditional McGoon ratio, Nakata index, and modified indices (measuring the narrowest diameters). Results. Patients with a McGoon ratio of 1.6 or less (modified £ 1.2) or a Nakata index of 150 mm2/m2 or less (modified £ 100 mm2/m2) were not at a higher risk of longer mechanical ventilation (p [ 0.87 [0.1] and p [ 0.68 [0.52], respectively), longer stay (p [ 0.52 [0.18] and
p [ 0.54 [0.38], respectively) in the intensive care unit, prolonged hospital stay (p [ 0.08 [0.26] and p [ 0.22 [0.29], respectively) or effusions (p [ 0.25 [0.37] and p [ 0.13 [0.06]), respectively). Younger and smaller children tended to have smaller PAs, but younger age (<24 months) and lower weight (<12 kg) were not predictive for poor early postoperative outcome. Conclusions. Small PAs do not significantly affect the early postoperative period after FO. In our opinion, there is no need to postpone the FO due to “smaller” PAs. The palliative procedures performed before FO to increase the size of the PA at the expense of volume overload of the single ventricle and the possible complications of prolonged cyanosis must be carefully weighed.
I
A remaining factor of concern before the Fontan pathway is the status of the pulmonary vascular bed. Although high PVR as a predictor for a negative outcome meets broad agreement [2, 3], the effect of the PA size is still controversial. Preservation of the single ventricle’s function by volume reduction, on the one hand, and stimulating pulmonary artery growth via increased pulmonary blood flow, on the other hand, needs delicate hemodynamic balancing before the Fontan operation (FO) [4]. This study aims to evaluate the influence of preoperative PA size on early outcome after the univentricular palliation in a time of advanced interventional and operative procedures more than 40 years after Fontan’s pathbreaking trial.
n 1977 Choussat and colleagues [1] presented 10 criteria for a reasonable patient selection before establishing a univentricular circuit. These “10 commandments” were age older than 4 years, adequate ventricular function, a competent atrioventricular valve, normal systemic venous drainage, normal right atrial volume, sinus rhythm, adequate pulmonary artery (PA) size, absence of PA distortion, low PA pressure (PAP), and low pulmonary vascular resistance (PVR) [1]. During the last 3 decades, modifications of the initial procedure, such as the establishment of an extracardiac conduit or an intracardiac lateral tunnel, as well as application of a fenestration, drew attention to other hemodynamic features, and the original selection criteria have been adapted.
(Ann Thorac Surg 2014;97:1387–93) Ó 2014 by The Society of Thoracic Surgeons
Patients and Methods Accepted for publication Nov 25, 2013. Address correspondence to Dr Lehner, Department of Pediatric Cardiology and Pediatric Intensive Care, University Hopstial Munich, Ludwig Maximilian University, Marchioninistrasse 15, 81377 Munich, Germany; e-mail: [email protected].
Ó 2014 by The Society of Thoracic Surgeons Published by Elsevier Inc
Between 2007 and 2012, 153 children underwent an intracardiac or extracardiac FO at the University Hospital in Munich. The study was approved by the Institutional Review Board of our institution. Informed consent for 0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2013.11.068
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LEHNER ET AL INFLUENCE OF PA SIZE ON EARLY POST-FO OUTCOME
Abbreviations and Acronyms
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AV DILV FO HLHS HRHS ICU LAP LPA PA PAP PVR Qp:Qs
= = = = = = = = = = = =
RPA SaO2 SD SV SVEDP
= = = = =
TGA
=
Atrioventricular double-inlet left ventricle Fontan operation hypoplastic left heart syndrome hypoplastic right heart syndrome intensive care unit left atrial pressure left pulmonary artery pulmonary artery pulmonary artery pressure pulmonary vascular resistance ratio of pulmonary blood flow to systemic blood flow right pulmonary artery arterial oxygen saturation standard deviation single ventricle systemic ventricular end-diastolic pressure transposition of the great arteries
treatment was obtained from the parents of each child. Retrospectively, their data, including age, weight, and height at FO were collected. Exact diagnoses of their univentricular circulation and the performed method of palliation (intracardiac tunnel with fenestration or extracardiac conduit) were registered. Furthermore, the early postoperative outcome for duration of mechanical ventilation, length of intensive care unit (ICU) and hospital stay, and duration of pleural or peritoneal effusions was evaluated. Our strategy was to leave the drainage tube in place until daily fluid loss was less than approximately 3 mL/kg. Cardiac catheterization data before the FO were available in 146 patients. Preoperative hemodynamic data and possible interventional procedures were noticed. With help of an Xcelera Workstation (Koninklijke Philips N.V., Amsterdam, Netherlands) traditional McGoon ratio and Nakata indices were calculated in angiographic loops. All measurements were done twice by 2 independent examiners. The McGoon ratio includes the combined diameters of both PAs and the diameter of the aorta just above diaphragm, whereas the Nakata index comprises the cross-sectional area of both PAs (mm2) and the patient’s body surface area (mm2) [5, 6]. Modified indices were also calculated using the narrowest diameters of both left and right PA, and only indexed measures of the PAs were statistically analyzed. To evaluate the influence of PA size on the early postoperative outcome, the patients was divided into groups. The first criterion of division was a McGoon ratio of 1.6 or less vs more than 1.6, and the second was a Nakata index of 150 mm2/m2 or less vs more than 150 mm2/m2. Afterward, we took a closer look at the patients with very small PAs and compared those with McGoon modified ratios of 1.2 or less vs patients with ratios exceeding 1.2 and modified Nakata indices of 100 mm2/m2 or less vs those exceeding 100 mm2/m2. Cutoff points for grouping were
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selected according to literature addressing the same or a similar discussion [7–10]. To evaluate if patients with prolonged effusions and longer hospital stay had significantly smaller PAs, we compared those with a hospital stay exceeding 14 days vs 14 days or less and patients with drainage exceeding 14 days with those who had an uncomplicated clinical course. Further investigations focused on the influence of preoperative interventional procedures such as balloon dilatation or stenting of the PAs. Finally, weight and age within our cohort were analyzed with respect to their predictive value on the early postoperative outcome after the FO.
Statistical Analysis Statistical analysis was performed with SigmaPlot 10 software (Systat Software Inc, Chicago, IL). Continuous variables are expressed as mean standard deviation or median (range). The 2-tailed Student t test or MannWhitney U test was performed for comparison of continuous variables between the groups and the Fisher exact test for categoric data. The Spearman rank correlation coefficient was used to evaluate the dependence between two nonparametric variables. A p value of less than 0.05 was considered significant.
Results Demographic Data In our study cohort, mean age at the FO was 3.6 2.4 years (range, 16 months to 18 years), and mean weight was 14.3 6.9 kg (range, 7.7 to 64.7 kg). The mean body surface area was 0.59 0.2 m2 (range, 0.39 to 1.65 m2). Most patients were diagnosed as having a hypoplastic left heart syndrome (n ¼ 80). The detailed diagnosis of all children is presented in Table 1. In 56 patients (38.4%), an intracardiac lateral atrial tunnel with a 2- to 3-mm fenestration was established using a polytetrafluoroethylene patch, whereas 90 children (61.6%) underwent an extracardiac repair with a polytetrafluoroethylene conduit 18 mm in diameter (Gore-Tex Vascular Graft; W.L. Gore & Associates, Dundee, Scotland, United Kingdom). In only 2 children from the extracardiac conduit group, a 2- to 4-mm fenestration was made because of an increased PAP during the cardiac Table 1. Cardiac Morphology Variable HLHS HLHS variants HRHS DILV TGA Others
No. (%) (N ¼ 146) 80 21 20 20 5
(54.8) (14.4) (13.7) (13.7) (3.4)
DILV ¼ double inlet left ventricle; HLHS ¼ hypoplastic left heart syndrome; HRHS ¼ hypoplastic right heart syndrome; TGA ¼ transposition of the great arteries.
LEHNER ET AL INFLUENCE OF PA SIZE ON EARLY POST-FO OUTCOME
Table 2. Angiographic Data for the Entire Study Population Variable McGoon ratio Modified McGoon ratio Nakata index, mm2/m2 Modified Nakata index, mm2/m2
Median (range) (N ¼ 146) 2.0 1.7 144.8 97.1
(0.9–3.6) (0.7–2.9) (58.8–540.1) (36.7–382.4)
catheterization before FO. The size of the fenestration was not adjusted to the status of the PAs.
PA Measurements In the available 146 angiograms, the median left PA (LPA) diameter was measured to be 6.85 mm (range, 0.8 to 16.0 mm), the median right PA (RPA) diameter was 7.5 mm (range, 1.7 to 16.8 mm), and the median aortic diameter at the level of the diaphragm was 7.0 mm (range, 5.0 to 15.00 mm). The median McGoon ratio and Nakata index calculated from these data, as well as modified indices in our entire patient population, are presented in Table 2. The groups with smaller and larger PAs did not differ significantly in preoperative demographic, echocardiographic, and hemodynamic data (Table 3).
Early Postoperative Variables The median time of mechanical ventilation in the 146 patients was 8 hours (range, 3 to 175 hours), the median stay in the ICU was 5 days (range, 1 to 26 days), the median hospital stay was 14 days (range, 5 to 57 days), and the median time of persistent effusions was 6 days (range, 1 to 42 days). The overall hospital mortality was 0%. A McGoon ratio of 1.6 or less was measured in 36 patients. Compared with their 110 companions with a McGoon ratio exceeding 1.6, patients with smaller PAs were not significantly longer intubated (p ¼ 0.87), did not stay significantly longer in the ICU (p ¼ 0.52) or in the hospital (p ¼ 0.08), and did not have effusions longer (p ¼ 0.25). Median hospital stay in the group with the smaller McGoon ratios was 19 days, whereas patients of the group with the larger PAs stayed a median of 14 days, but the difference did not reach statistical significance (Table 4). The 77 children with a Nakata index of 150 mm2/m2 or less were compared with the 69 children who whose index exceeded 150 mm2/m2. Like the McGoon measurements, these data also showed no significant differences concerning intubation time (p ¼ 0.68), ICU (p ¼ 0.54) and hospital stay (p ¼ 0.22), or days of pericardial or pleural drainage (p ¼ 0.13; Table 4). Concerning 26 patients with very small PAs and a modified McGoon ratio of 1.2 or less vs 120 patients with a McGoon ratio exceeding 1.2, all early postoperative follow-up variables showed no significant differences between the groups. The children with smaller PAs had a tendency to stay longer in hospital but without statistical significance (median hospital stay was 20 days in the first group vs 14 days in the second group; Table 4).
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After modified McGoon ratios were analyzed, the modified Nakata indices were analyzed. Again, there was no difference between the 74 children with a modified Nakata index of 100 mm2/m2 or less and the 72 with a modified Nakata index exceeding 100 mm2/m2 concerning time of intubation (p ¼ 0.52), time in the ICU (p ¼ 0.38), hospital stay (p ¼ 0.29), and days with drainage (p ¼ 0.06; Table 4). Spearman correlation analysis showed a tendency among children with smaller PAs to be longer on the ventilator, to stay longer in the ICU, to stay longer in hospital, and to have prolonged effusions, but without significant differences between the groups (Figs 1A, 1B). Younger patients (aged < 24 months) tended to have smaller PA diameters: median McGoon ratio was 1.9 (range, 1.2 to 2.9) vs. 2.0 (range, 0.9 to 3.7) for the older children; the median Nakata index was 141.2 mm2/m2 (range, 103.8 to 270.2 mm2/m2) vs 148.2 mm2/m2 (range, 58.8 to 540.1 mm2/m2). Smaller children (<12 kg) manifested also a tendency to have smaller PAs: median McGoon ratio was 1.9 (range, 1.1 to 2.9) vs 2.1 (range, 0.9 to 3.7) for children heavier than 12 kg; median Nakata was 144.9 mm2/m2 (range,71.4 to 290.7 mm2/m2) vs 149.3 mm2/m2 (range, 58.8 to 530.1 mm2/m2). However, younger and smaller children did not present a more complicated early postoperative course (Figs 2A, 2B).
Comment When the original FO was performed without any intermediate steps, an adequate PA size was considered to be of greatest importance for a successful clinical course. Fontan and colleagues [11] showed in their data of 334 patients in 1989 that the “dimensions of the right and left PAs [ . ] were one of the most powerful risk factors for death or takedown from the Fontan operation.” As published by McGoon and colleagues [5] in 1975 and Nakata and colleagues [6] in 1984, two evaluation methods exist for the dimensions of the PAs. For a successful FO, a McGoon ratio greater than 1.8 and a Nakata index of more than 250 mm2/m2 were thought to be the minimum required [5, 6]. In the early years after the FO was initiated, publications like those from Knott-Craig and colleagues [12] and Senzaki and colleagues [13] confirmed Fontan’s claim for a adequate size of the PAs. They showed that the early hemodynamics of their palliated patients was adversely influenced by lower PA indices. In recent decades, due to modifications to the initial procedure, the effect of the PA size on the FO hemodynamics was further investigated. Chowdhury and colleagues [14] showed in a histomorphologic study in 2010 that a Nakata index lower than 200 mm2/m2 was significantly associated with severe intimal lesions, thrombus formation, and a poorer postoperative outcome of their 44 Fontan patients. When the FO with a lateral tunnel was compared with an extracardiac conduit formation, Fiore and colleagues [8] mentioned that two of three of their Fontan takedowns had to be performed in patients with very small PAs
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Table 3. Demographic, Echocardiographic, and Hemodynamic Data With Respect to Pulmonary Artery Size Nakata Index, mm2/m2
McGoon Ratio >1.6 (n ¼ 110)
1.6 (n ¼ 36)
3.1 2.4 2 (1–17)
3.0 3.1 2 (1–18)
14.5 7.1 12.6 (9.1–64.7) 20 (18.2) 2 (1.8)
13.5 6.9 12 (7.7–48) 7 (19.4) 0 (0)
10.4 3.8 10.5 (0–16)
9.9 2.2 10 (4–15)
11.2 2.6 11 (5–19)
10.8 2.3 11 (7–17)
7.2 2.2 7 (2–15)
7.0 1.7 7 (4–11)
0.69 0.2 0.7 (0.3–1.4)
0.63 0.2 1 (0.3–1.5)
85.2 4.7 85 (72.3–93.5)
83.6 4.9 85 (72.3–92.7)
Variable
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Age, y Mean SD Median (range) Weight, kg Mean SD Median (range) AV valve regurgitation II, III SV reduced function SVEDP, mm Hg Mean SD Median (range) PAP, mm Hg Mean SD Median (range) LAP, mm Hg Mean SD Median (range) Qp:Qs Mean SD Median (range) SaO2, % Mean SD Median (range)
p Value
>150 (n ¼ 69)
150 (n ¼ 77)
3.4 2.9 2 (1–18)
2.9 2.3 2 (1–17)
15.0 8.6 12 (11.3–13.3) 16 (23.2) 2 (2.9)
13.5 5.3 13 (7.7–64.7) 9 (11.7) 0 (0)
10.7 4.0 11 (0–12)
10.1 3.3 10 (0–17)
11.5 1.6 12 (6–15)
11.1 2.6 11 (5–19)
6.9 2.0 8 (2–10)
7.3 2.3 7 (3–15)
0.70 0.2 1 (0.4–1.4)
0.66 0.2 1 (0.3–1.5)
84.8 5.6 (72.3–93.4)
84.7 4.5 (74.7–93.5)
0.79
p Value 0.25
0.49
0.21
0.87 0.42 0.53
0.07 0.14 0.37
0.49
0.16
0.31 0.14
0.12
0.37
0.10
0.91
Continuous data are shown as indicated and categoric data as number (%). AV ¼ atrioventricular; LAP ¼ left atrial pressure; PAP ¼ pulmonary artery pressure; Qp:Qs ¼ pulmonary-to-systemic blood flow ratio; SD ¼ standard deviation; SV ¼ single ventricle; SVEDP ¼ systemic ventricular end-diastolic pressure. SaO2 ¼ arterial oxygen saturation;
(McGoon ratio < 1.4) and identified a McGoon ratio of less than 1.5 as a risk factor for the operation. With respect to the midterm outcome, a study by Ovroutski
and colleagues [15] in 2009 also showed that a Nakata index below 150 mm2/m2 was correlated with an unfavorable follow-up.
Table 4. Pulmonary Artery Measurements and Early Postoperative Parameters Nakata Index, mm2/m2
McGoon Ratio Variablea
>1.6 (n ¼ 110)
1.6 (n ¼ 36)
Intubated, h ICU stay, d Hospital stay, d Effusions, d
8.0 5.0 14 6
8.0 4.0 19 6
(3–175) (1–26) (5–57) (1–62)
(5–30) (2–16) (9–33) (1–42)
p Value 0.87 0.52 0.08 0.25
Intubated, h ICU stay, d Hospital stay, d Effusions, d a
1.2 (n ¼ 26)
8.0 5.0 14 6
7.0 4.0 20 7
(3–175) (1–126) (5–57) (1–62)
Data are presented as median value and range.
ICU ¼ intensive care unit.
(5–23) (2–16) (7–33) (2–24)
8.0 4.0 14 6.0
(3–149) (1–26) (5–57) (1–30)
150 (n ¼ 77) 8.0 5.0 15 7
(3–175) (1–16) (6–56) (1–42)
p Value 0.68 0.54 0.22 0.13
Modified Nakata Index, mm2/m2
Modified McGoon Ratio >1.2 (n ¼ 120)
>150 (n ¼ 69)
p Value 0.1 0.18 0.26 0.37
>100 (n ¼ 74) 8.0 4.0 14 5.0
(3–149) (1–18) (5–57) (1–42)
100 (n ¼ 72) 8.0 5.0 16 7
(4–175) (1–26) (6–41) (1–30)
p Value 0.52 0.38 0.29 0.06
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B
Fig 1. Correlation between (A) the McGoon ratio or (B) the Nakata index and the early follow-up variables. Spearman correlation shows no significant dependence between the McGoon ratio or Nakata index and the early follow-up variables of time on mechanical ventilation (black circles) (r ¼ 0.003, p ¼ 0.97; or r ¼ –0.03, p ¼ 0.72), intensive care unit (ICU) stay (clear circles) (r ¼ –0.04, p ¼ 0.64; or r ¼ –0.05, p ¼ 0.54), hospital stay (black triangle) (r ¼ –0.098, p ¼ 0.24; or r ¼ –0.10, p ¼ 0.21), and duration of effusions (clear triangle) (r ¼ –0.04, p ¼ 0.65; or r ¼ –0.12, p ¼ 0.14).
However, as Senzaki and colleagues [13] already mentioned in 1994, it is questionable whether the difference of the proximal PA diameter could be an indicator for the overall status of the pulmonary vascular bed and PVR. In a study of 406 univentricular patients, Hosein and colleagues [16] identified a PAP higher than 15 mm Hg and an impaired ventricular function as the only two risk factors for a poorer early and late FO outcome in the current era. The PA size did not significantly influence death, Fontan takedown, or need for transplantation. Rogers and colleagues [17] showed similar results in 771 consecutive patients who
were retrospectively reviewed for factors influencing perioperative morbidity and death. Regardless of the anatomic status of the PAs a PAP exceeding 15 mm Hg was 90% specific for predicting prolonged effusions, longer hospital stay, and death [17]. Our study focused only on PA size and its influence on the early postoperative course. Small size of the PAs has never been a contraindication for the FO in our center. Exclusion criteria could be a poor overall clinical status, due to concomitant adverse cardiac malformations or to an elevated PAP (>15 mm Hg), but not due to the PA configuration. According to our data, smaller PA size,
Fig 2. An evaluation of the early follow-up variables with respect to (A) age and (B) weight shows that younger and smaller patients do not show a significantly prolonged early follow-up compared with their older and bigger companions. The horizontal line in the middle of each box indicates the median; the top and bottom borders of the box mark the 75th and 25th percentiles, respectively; the whiskers mark the 90th and 10th percentiles; and the black circles indicate outliers. (ICU ¼ intensive care unit.)
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measured by the McGoon ratio or Nakata index, showed no adverse influence on the early postoperative outcome of our Fontan patients. Even patients with a McGoon ratio of approximately 1.2 and a Nakata index of approximately 100 mm2/m2 showed an uncomplicated follow-up, easily comparable with patients with larger PAs. No patients died, and no early takedown of the Fontan circulation had to be undertaken. Our results support the experience of Adachi and colleagues [7], who compared patients with Nakata indices down to a minimal 104 mm2/m2 vs patients with PAs sized approximately 300 mm2/m2 and found that even patients with a Nakata index of approximately 100 mm2/m2 had as good a recovery as their other patients [7]. In our study population, definitive univentricular palliation was done at a median age of 2 years. Age was considered above weight as cutoff criterion. Younger and lighter patients (aged < 24 months [n ¼ 18]; weight < 12 kg [n ¼ 63]) tended to have smaller PAs; however, this subset did not show a significantly poorer early outcome than their older and heavier companions. Ikai and colleagues [18] found in their study of 72 patients concerning the timing of the FO that the younger subsets experienced longer peritoneal drainage and a longer hospital stay. In our study, neither age nor weight showed significant influence on postoperative effusions and hospital length of stay. Even the smallest patient (7.68 kg at 16 months old) with fragile PA status (modified McGoon ratio, 0.8; modified Nakata index, 96.7 mm/m2) showed no adverse events and was discharged from the hospital after 12 uneventful postoperative days. These findings are in line with the recent reports of Sathanandam and colleagues [9] and Pizarro and colleagues [19], who stated that the FO can be performed safely and with favorable outcome in patients at or younger than 2 years of age and weighing less than 10 kg. The reason for an early FO is to eliminate the patient’s cyanosis and to relieve the single systemic ventricle from volume overload, which should preserve its function for a possibly long period [20–22]. The volume reduction is not a consequence of the FO per se but is secondary to avoidance of the collateral vessels development, which is usually stimulated by the long-standing cyanosis. Our general strategy is to close all sources of additional blood flow during the early-performed second-stage palliation (Glenn or hemi-FO). A remarkable finding that supports an early staging to preserve single ventricle function is mentioned in the publication of Baek and colleagues [22]. They could show in their study on late Fontan patients that in those where palliative procedures were left in place longer to promote PA growth and who had consequently the larger PAs had also significantly higher blood levels of brain natriuretic peptide. Because brain natriuretic peptide is a marker for excessive heart muscle stretching and from there for left ventricular dysfunction, the authors concluded that this may be indirect neurohumoral evidence for the adverse influence of late unloading on the future ventricular function. During their follow-up period since 1986, they could
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not find a disadvantage of small PAs on late functional outcome [22]. Ota and colleagues [20] furthermore pointed out that long-standing cyanosis and chronic volume overload, due to postponing the FO with hope that PAs will grow, could cause progressive ventricular fibrosis and impaired systolic and diastolic function [20]. These findings support our approach not to perform pre-Fontan PA augmentation procedures, including creation or leaving of aortopulmonary shunts during the second-stage procedure, even in patients with very small PAs, at the expense of an additional ventricular load. Of Choussat’s 10 commandments for a successful univentricular palliation, nowadays ventricular function and the status of the pulmonary vasculature seem to be the most concerning issues before the FO [9, 17, 21]. According to our results, smaller PA diameters measured using McGoon ratio and Nakata index do not adversely influence the Fontan palliation’s early outcome. Rapid staging in younger and smaller patients to preserve the single ventricle function is possible with good early results. In our opinion, there is no need to postpone the Fontan operation due to “smaller” PAs. The palliative procedures performed before FO to increase the size of the PAs at the expense of volume overload of the single ventricle and possible complications of prolonged cyanosis must be carefully weighed.
References 1. Choussat A, Fontan F, Bedde B, et al. Selection criteria for Fontan’s procedure. In: Anderson RH, Shinebourne EA, eds. Paediatric cardiology. Edinburgh; New York: Churchill Livingstone; 1977:559–66. 2. Gewillig M, Brown SC, Eysekens B, et al. The Fontan circulation: who controls cardiac output? Interact Cardiovasc Thorac Surg 2010;10:428–33. 3. Ciliberti P, Schulze-Neick I, Giardini A. Modulation of pulmonary vascular resistance as target for therapeutic interventions in Fontan patients: focus on phosphodiesterase inhibitors. Future Cardiol 2012;8:271–84. 4. Gewillig M, Brown SC, Heying R, et al. Volume load paradox while preparing for the Fontan: not too much for the ventricle, not too little for the lungs. Interact Cardiovasc Thorac Surg 2010;10:262–5. 5. McGoon DC, Baird DK, Davis GD. Surgical management of large bronchial collateral arteries with pulmonary stenosis or atresia. Circulation 1975;52:109–18. 6. Nakata S, Imai Y, Takanashi Y, et al. A new method for the quantitative standardization of cross-sectional areas of the pulmonary arteries in congenital heart diseases with decreased pulmonary blood flow. J Thorac Cardiovasc Surg 1984;88:610–9. 7. Adachi I, Yagihara T, Kagisaki K, et al. Preoperative small pulmonary artery did not affect the midterm results of Fontan operation. Eur J Cardiothorac Surg 2007;32:156–62. 8. Fiore A, Turrentine M, Rodefeld M, et al. Fontan operation: a comparison of lateral tunnel with extracardiac conduit. Ann Thorac Surg 2007;83:622–30. 9. Sathanandam S, Polimenakos A, Blair C, et al. Hypoplastic left heart syndrome: feasibility study for patients undergoing Fontan completion at or prior to two years of age. Ann Thorac Surg 2010;90:821–9. 10. Seckeler M, Mery C, Gangemi J, et al. An angiographic predictor of pulmonary artery stenosis after the NorwoodSano operation for hypoplastic left heart syndrome. Pediatr Cardiol 2012;33:1281–7.
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CONGENITAL HEART SURGERY: The Annals of Thoracic Surgery CME Program is located online at http://www.annalsthoracicsurgery.org/cme/ home. To take the CME activity related to this article, you must have either an STS member or an individual non-member subscription to the journal.
Anja Lehner, MD, Anna Schuh, MS, Florian E. M. Herrmann, MS, Martin Riester, MD, Sabine Pallivathukal, MD, Robert Dalla-Pozza, MD, PhD, Rainer Kozlik-Feldmann, MD, PhD, Heinrich Netz, MD, PhD, Edward Malec, MD, PhD, and Katarzyna Januszewska, MD, PhD Department of Pediatric Cardiology and Pediatric Intensive Care, University Hospital Munich, Ludwig Maximilian University, Munich, Germany; and Department of Cardiothoracic Surgery, Division of Pediatric Cardiac Surgery, University Hospital Muenster, WestfalianWilhelm’s-University, Muenster, Germany
Background. Small pulmonary arteries (PAs) are often considered as a contraindication for the Fontan operation (FO). The aim of this study was to evaluate if the PA size is still one of the major impact factors on the postoperative early outcome. Methods. Data of 146 patients, with a median age of 2.0 years (range, 1.5 to 18 years) and a median weight of 12.45 kg (range, 7.7 to 64.7 kg) who underwent a modified FO in the same center between 2007 and 2012 were retrospectively analyzed with respect to the traditional McGoon ratio, Nakata index, and modified indices (measuring the narrowest diameters). Results. Patients with a McGoon ratio of 1.6 or less (modified £ 1.2) or a Nakata index of 150 mm2/m2 or less (modified £ 100 mm2/m2) were not at a higher risk of longer mechanical ventilation (p [ 0.87 [0.1] and p [ 0.68 [0.52], respectively), longer stay (p [ 0.52 [0.18] and
p [ 0.54 [0.38], respectively) in the intensive care unit, prolonged hospital stay (p [ 0.08 [0.26] and p [ 0.22 [0.29], respectively) or effusions (p [ 0.25 [0.37] and p [ 0.13 [0.06]), respectively). Younger and smaller children tended to have smaller PAs, but younger age (<24 months) and lower weight (<12 kg) were not predictive for poor early postoperative outcome. Conclusions. Small PAs do not significantly affect the early postoperative period after FO. In our opinion, there is no need to postpone the FO due to “smaller” PAs. The palliative procedures performed before FO to increase the size of the PA at the expense of volume overload of the single ventricle and the possible complications of prolonged cyanosis must be carefully weighed.
I
A remaining factor of concern before the Fontan pathway is the status of the pulmonary vascular bed. Although high PVR as a predictor for a negative outcome meets broad agreement [2, 3], the effect of the PA size is still controversial. Preservation of the single ventricle’s function by volume reduction, on the one hand, and stimulating pulmonary artery growth via increased pulmonary blood flow, on the other hand, needs delicate hemodynamic balancing before the Fontan operation (FO) [4]. This study aims to evaluate the influence of preoperative PA size on early outcome after the univentricular palliation in a time of advanced interventional and operative procedures more than 40 years after Fontan’s pathbreaking trial.
n 1977 Choussat and colleagues [1] presented 10 criteria for a reasonable patient selection before establishing a univentricular circuit. These “10 commandments” were age older than 4 years, adequate ventricular function, a competent atrioventricular valve, normal systemic venous drainage, normal right atrial volume, sinus rhythm, adequate pulmonary artery (PA) size, absence of PA distortion, low PA pressure (PAP), and low pulmonary vascular resistance (PVR) [1]. During the last 3 decades, modifications of the initial procedure, such as the establishment of an extracardiac conduit or an intracardiac lateral tunnel, as well as application of a fenestration, drew attention to other hemodynamic features, and the original selection criteria have been adapted.
(Ann Thorac Surg 2014;97:1387–93) Ó 2014 by The Society of Thoracic Surgeons
Patients and Methods Accepted for publication Nov 25, 2013. Address correspondence to Dr Lehner, Department of Pediatric Cardiology and Pediatric Intensive Care, University Hopstial Munich, Ludwig Maximilian University, Marchioninistrasse 15, 81377 Munich, Germany; e-mail: [email protected].
Ó 2014 by The Society of Thoracic Surgeons Published by Elsevier Inc
Between 2007 and 2012, 153 children underwent an intracardiac or extracardiac FO at the University Hospital in Munich. The study was approved by the Institutional Review Board of our institution. Informed consent for 0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2013.11.068
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Influence of Pulmonary Artery Size on Early Outcome After the Fontan Operation
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LEHNER ET AL INFLUENCE OF PA SIZE ON EARLY POST-FO OUTCOME
Abbreviations and Acronyms
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AV DILV FO HLHS HRHS ICU LAP LPA PA PAP PVR Qp:Qs
= = = = = = = = = = = =
RPA SaO2 SD SV SVEDP
= = = = =
TGA
=
Atrioventricular double-inlet left ventricle Fontan operation hypoplastic left heart syndrome hypoplastic right heart syndrome intensive care unit left atrial pressure left pulmonary artery pulmonary artery pulmonary artery pressure pulmonary vascular resistance ratio of pulmonary blood flow to systemic blood flow right pulmonary artery arterial oxygen saturation standard deviation single ventricle systemic ventricular end-diastolic pressure transposition of the great arteries
treatment was obtained from the parents of each child. Retrospectively, their data, including age, weight, and height at FO were collected. Exact diagnoses of their univentricular circulation and the performed method of palliation (intracardiac tunnel with fenestration or extracardiac conduit) were registered. Furthermore, the early postoperative outcome for duration of mechanical ventilation, length of intensive care unit (ICU) and hospital stay, and duration of pleural or peritoneal effusions was evaluated. Our strategy was to leave the drainage tube in place until daily fluid loss was less than approximately 3 mL/kg. Cardiac catheterization data before the FO were available in 146 patients. Preoperative hemodynamic data and possible interventional procedures were noticed. With help of an Xcelera Workstation (Koninklijke Philips N.V., Amsterdam, Netherlands) traditional McGoon ratio and Nakata indices were calculated in angiographic loops. All measurements were done twice by 2 independent examiners. The McGoon ratio includes the combined diameters of both PAs and the diameter of the aorta just above diaphragm, whereas the Nakata index comprises the cross-sectional area of both PAs (mm2) and the patient’s body surface area (mm2) [5, 6]. Modified indices were also calculated using the narrowest diameters of both left and right PA, and only indexed measures of the PAs were statistically analyzed. To evaluate the influence of PA size on the early postoperative outcome, the patients was divided into groups. The first criterion of division was a McGoon ratio of 1.6 or less vs more than 1.6, and the second was a Nakata index of 150 mm2/m2 or less vs more than 150 mm2/m2. Afterward, we took a closer look at the patients with very small PAs and compared those with McGoon modified ratios of 1.2 or less vs patients with ratios exceeding 1.2 and modified Nakata indices of 100 mm2/m2 or less vs those exceeding 100 mm2/m2. Cutoff points for grouping were
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selected according to literature addressing the same or a similar discussion [7–10]. To evaluate if patients with prolonged effusions and longer hospital stay had significantly smaller PAs, we compared those with a hospital stay exceeding 14 days vs 14 days or less and patients with drainage exceeding 14 days with those who had an uncomplicated clinical course. Further investigations focused on the influence of preoperative interventional procedures such as balloon dilatation or stenting of the PAs. Finally, weight and age within our cohort were analyzed with respect to their predictive value on the early postoperative outcome after the FO.
Statistical Analysis Statistical analysis was performed with SigmaPlot 10 software (Systat Software Inc, Chicago, IL). Continuous variables are expressed as mean standard deviation or median (range). The 2-tailed Student t test or MannWhitney U test was performed for comparison of continuous variables between the groups and the Fisher exact test for categoric data. The Spearman rank correlation coefficient was used to evaluate the dependence between two nonparametric variables. A p value of less than 0.05 was considered significant.
Results Demographic Data In our study cohort, mean age at the FO was 3.6 2.4 years (range, 16 months to 18 years), and mean weight was 14.3 6.9 kg (range, 7.7 to 64.7 kg). The mean body surface area was 0.59 0.2 m2 (range, 0.39 to 1.65 m2). Most patients were diagnosed as having a hypoplastic left heart syndrome (n ¼ 80). The detailed diagnosis of all children is presented in Table 1. In 56 patients (38.4%), an intracardiac lateral atrial tunnel with a 2- to 3-mm fenestration was established using a polytetrafluoroethylene patch, whereas 90 children (61.6%) underwent an extracardiac repair with a polytetrafluoroethylene conduit 18 mm in diameter (Gore-Tex Vascular Graft; W.L. Gore & Associates, Dundee, Scotland, United Kingdom). In only 2 children from the extracardiac conduit group, a 2- to 4-mm fenestration was made because of an increased PAP during the cardiac Table 1. Cardiac Morphology Variable HLHS HLHS variants HRHS DILV TGA Others
No. (%) (N ¼ 146) 80 21 20 20 5
(54.8) (14.4) (13.7) (13.7) (3.4)
DILV ¼ double inlet left ventricle; HLHS ¼ hypoplastic left heart syndrome; HRHS ¼ hypoplastic right heart syndrome; TGA ¼ transposition of the great arteries.
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Table 2. Angiographic Data for the Entire Study Population Variable McGoon ratio Modified McGoon ratio Nakata index, mm2/m2 Modified Nakata index, mm2/m2
Median (range) (N ¼ 146) 2.0 1.7 144.8 97.1
(0.9–3.6) (0.7–2.9) (58.8–540.1) (36.7–382.4)
catheterization before FO. The size of the fenestration was not adjusted to the status of the PAs.
PA Measurements In the available 146 angiograms, the median left PA (LPA) diameter was measured to be 6.85 mm (range, 0.8 to 16.0 mm), the median right PA (RPA) diameter was 7.5 mm (range, 1.7 to 16.8 mm), and the median aortic diameter at the level of the diaphragm was 7.0 mm (range, 5.0 to 15.00 mm). The median McGoon ratio and Nakata index calculated from these data, as well as modified indices in our entire patient population, are presented in Table 2. The groups with smaller and larger PAs did not differ significantly in preoperative demographic, echocardiographic, and hemodynamic data (Table 3).
Early Postoperative Variables The median time of mechanical ventilation in the 146 patients was 8 hours (range, 3 to 175 hours), the median stay in the ICU was 5 days (range, 1 to 26 days), the median hospital stay was 14 days (range, 5 to 57 days), and the median time of persistent effusions was 6 days (range, 1 to 42 days). The overall hospital mortality was 0%. A McGoon ratio of 1.6 or less was measured in 36 patients. Compared with their 110 companions with a McGoon ratio exceeding 1.6, patients with smaller PAs were not significantly longer intubated (p ¼ 0.87), did not stay significantly longer in the ICU (p ¼ 0.52) or in the hospital (p ¼ 0.08), and did not have effusions longer (p ¼ 0.25). Median hospital stay in the group with the smaller McGoon ratios was 19 days, whereas patients of the group with the larger PAs stayed a median of 14 days, but the difference did not reach statistical significance (Table 4). The 77 children with a Nakata index of 150 mm2/m2 or less were compared with the 69 children who whose index exceeded 150 mm2/m2. Like the McGoon measurements, these data also showed no significant differences concerning intubation time (p ¼ 0.68), ICU (p ¼ 0.54) and hospital stay (p ¼ 0.22), or days of pericardial or pleural drainage (p ¼ 0.13; Table 4). Concerning 26 patients with very small PAs and a modified McGoon ratio of 1.2 or less vs 120 patients with a McGoon ratio exceeding 1.2, all early postoperative follow-up variables showed no significant differences between the groups. The children with smaller PAs had a tendency to stay longer in hospital but without statistical significance (median hospital stay was 20 days in the first group vs 14 days in the second group; Table 4).
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After modified McGoon ratios were analyzed, the modified Nakata indices were analyzed. Again, there was no difference between the 74 children with a modified Nakata index of 100 mm2/m2 or less and the 72 with a modified Nakata index exceeding 100 mm2/m2 concerning time of intubation (p ¼ 0.52), time in the ICU (p ¼ 0.38), hospital stay (p ¼ 0.29), and days with drainage (p ¼ 0.06; Table 4). Spearman correlation analysis showed a tendency among children with smaller PAs to be longer on the ventilator, to stay longer in the ICU, to stay longer in hospital, and to have prolonged effusions, but without significant differences between the groups (Figs 1A, 1B). Younger patients (aged < 24 months) tended to have smaller PA diameters: median McGoon ratio was 1.9 (range, 1.2 to 2.9) vs. 2.0 (range, 0.9 to 3.7) for the older children; the median Nakata index was 141.2 mm2/m2 (range, 103.8 to 270.2 mm2/m2) vs 148.2 mm2/m2 (range, 58.8 to 540.1 mm2/m2). Smaller children (<12 kg) manifested also a tendency to have smaller PAs: median McGoon ratio was 1.9 (range, 1.1 to 2.9) vs 2.1 (range, 0.9 to 3.7) for children heavier than 12 kg; median Nakata was 144.9 mm2/m2 (range,71.4 to 290.7 mm2/m2) vs 149.3 mm2/m2 (range, 58.8 to 530.1 mm2/m2). However, younger and smaller children did not present a more complicated early postoperative course (Figs 2A, 2B).
Comment When the original FO was performed without any intermediate steps, an adequate PA size was considered to be of greatest importance for a successful clinical course. Fontan and colleagues [11] showed in their data of 334 patients in 1989 that the “dimensions of the right and left PAs [ . ] were one of the most powerful risk factors for death or takedown from the Fontan operation.” As published by McGoon and colleagues [5] in 1975 and Nakata and colleagues [6] in 1984, two evaluation methods exist for the dimensions of the PAs. For a successful FO, a McGoon ratio greater than 1.8 and a Nakata index of more than 250 mm2/m2 were thought to be the minimum required [5, 6]. In the early years after the FO was initiated, publications like those from Knott-Craig and colleagues [12] and Senzaki and colleagues [13] confirmed Fontan’s claim for a adequate size of the PAs. They showed that the early hemodynamics of their palliated patients was adversely influenced by lower PA indices. In recent decades, due to modifications to the initial procedure, the effect of the PA size on the FO hemodynamics was further investigated. Chowdhury and colleagues [14] showed in a histomorphologic study in 2010 that a Nakata index lower than 200 mm2/m2 was significantly associated with severe intimal lesions, thrombus formation, and a poorer postoperative outcome of their 44 Fontan patients. When the FO with a lateral tunnel was compared with an extracardiac conduit formation, Fiore and colleagues [8] mentioned that two of three of their Fontan takedowns had to be performed in patients with very small PAs
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Table 3. Demographic, Echocardiographic, and Hemodynamic Data With Respect to Pulmonary Artery Size Nakata Index, mm2/m2
McGoon Ratio >1.6 (n ¼ 110)
1.6 (n ¼ 36)
3.1 2.4 2 (1–17)
3.0 3.1 2 (1–18)
14.5 7.1 12.6 (9.1–64.7) 20 (18.2) 2 (1.8)
13.5 6.9 12 (7.7–48) 7 (19.4) 0 (0)
10.4 3.8 10.5 (0–16)
9.9 2.2 10 (4–15)
11.2 2.6 11 (5–19)
10.8 2.3 11 (7–17)
7.2 2.2 7 (2–15)
7.0 1.7 7 (4–11)
0.69 0.2 0.7 (0.3–1.4)
0.63 0.2 1 (0.3–1.5)
85.2 4.7 85 (72.3–93.5)
83.6 4.9 85 (72.3–92.7)
Variable
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Age, y Mean SD Median (range) Weight, kg Mean SD Median (range) AV valve regurgitation II, III SV reduced function SVEDP, mm Hg Mean SD Median (range) PAP, mm Hg Mean SD Median (range) LAP, mm Hg Mean SD Median (range) Qp:Qs Mean SD Median (range) SaO2, % Mean SD Median (range)
p Value
>150 (n ¼ 69)
150 (n ¼ 77)
3.4 2.9 2 (1–18)
2.9 2.3 2 (1–17)
15.0 8.6 12 (11.3–13.3) 16 (23.2) 2 (2.9)
13.5 5.3 13 (7.7–64.7) 9 (11.7) 0 (0)
10.7 4.0 11 (0–12)
10.1 3.3 10 (0–17)
11.5 1.6 12 (6–15)
11.1 2.6 11 (5–19)
6.9 2.0 8 (2–10)
7.3 2.3 7 (3–15)
0.70 0.2 1 (0.4–1.4)
0.66 0.2 1 (0.3–1.5)
84.8 5.6 (72.3–93.4)
84.7 4.5 (74.7–93.5)
0.79
p Value 0.25
0.49
0.21
0.87 0.42 0.53
0.07 0.14 0.37
0.49
0.16
0.31 0.14
0.12
0.37
0.10
0.91
Continuous data are shown as indicated and categoric data as number (%). AV ¼ atrioventricular; LAP ¼ left atrial pressure; PAP ¼ pulmonary artery pressure; Qp:Qs ¼ pulmonary-to-systemic blood flow ratio; SD ¼ standard deviation; SV ¼ single ventricle; SVEDP ¼ systemic ventricular end-diastolic pressure. SaO2 ¼ arterial oxygen saturation;
(McGoon ratio < 1.4) and identified a McGoon ratio of less than 1.5 as a risk factor for the operation. With respect to the midterm outcome, a study by Ovroutski
and colleagues [15] in 2009 also showed that a Nakata index below 150 mm2/m2 was correlated with an unfavorable follow-up.
Table 4. Pulmonary Artery Measurements and Early Postoperative Parameters Nakata Index, mm2/m2
McGoon Ratio Variablea
>1.6 (n ¼ 110)
1.6 (n ¼ 36)
Intubated, h ICU stay, d Hospital stay, d Effusions, d
8.0 5.0 14 6
8.0 4.0 19 6
(3–175) (1–26) (5–57) (1–62)
(5–30) (2–16) (9–33) (1–42)
p Value 0.87 0.52 0.08 0.25
Intubated, h ICU stay, d Hospital stay, d Effusions, d a
1.2 (n ¼ 26)
8.0 5.0 14 6
7.0 4.0 20 7
(3–175) (1–126) (5–57) (1–62)
Data are presented as median value and range.
ICU ¼ intensive care unit.
(5–23) (2–16) (7–33) (2–24)
8.0 4.0 14 6.0
(3–149) (1–26) (5–57) (1–30)
150 (n ¼ 77) 8.0 5.0 15 7
(3–175) (1–16) (6–56) (1–42)
p Value 0.68 0.54 0.22 0.13
Modified Nakata Index, mm2/m2
Modified McGoon Ratio >1.2 (n ¼ 120)
>150 (n ¼ 69)
p Value 0.1 0.18 0.26 0.37
>100 (n ¼ 74) 8.0 4.0 14 5.0
(3–149) (1–18) (5–57) (1–42)
100 (n ¼ 72) 8.0 5.0 16 7
(4–175) (1–26) (6–41) (1–30)
p Value 0.52 0.38 0.29 0.06
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B
Fig 1. Correlation between (A) the McGoon ratio or (B) the Nakata index and the early follow-up variables. Spearman correlation shows no significant dependence between the McGoon ratio or Nakata index and the early follow-up variables of time on mechanical ventilation (black circles) (r ¼ 0.003, p ¼ 0.97; or r ¼ –0.03, p ¼ 0.72), intensive care unit (ICU) stay (clear circles) (r ¼ –0.04, p ¼ 0.64; or r ¼ –0.05, p ¼ 0.54), hospital stay (black triangle) (r ¼ –0.098, p ¼ 0.24; or r ¼ –0.10, p ¼ 0.21), and duration of effusions (clear triangle) (r ¼ –0.04, p ¼ 0.65; or r ¼ –0.12, p ¼ 0.14).
However, as Senzaki and colleagues [13] already mentioned in 1994, it is questionable whether the difference of the proximal PA diameter could be an indicator for the overall status of the pulmonary vascular bed and PVR. In a study of 406 univentricular patients, Hosein and colleagues [16] identified a PAP higher than 15 mm Hg and an impaired ventricular function as the only two risk factors for a poorer early and late FO outcome in the current era. The PA size did not significantly influence death, Fontan takedown, or need for transplantation. Rogers and colleagues [17] showed similar results in 771 consecutive patients who
were retrospectively reviewed for factors influencing perioperative morbidity and death. Regardless of the anatomic status of the PAs a PAP exceeding 15 mm Hg was 90% specific for predicting prolonged effusions, longer hospital stay, and death [17]. Our study focused only on PA size and its influence on the early postoperative course. Small size of the PAs has never been a contraindication for the FO in our center. Exclusion criteria could be a poor overall clinical status, due to concomitant adverse cardiac malformations or to an elevated PAP (>15 mm Hg), but not due to the PA configuration. According to our data, smaller PA size,
Fig 2. An evaluation of the early follow-up variables with respect to (A) age and (B) weight shows that younger and smaller patients do not show a significantly prolonged early follow-up compared with their older and bigger companions. The horizontal line in the middle of each box indicates the median; the top and bottom borders of the box mark the 75th and 25th percentiles, respectively; the whiskers mark the 90th and 10th percentiles; and the black circles indicate outliers. (ICU ¼ intensive care unit.)
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measured by the McGoon ratio or Nakata index, showed no adverse influence on the early postoperative outcome of our Fontan patients. Even patients with a McGoon ratio of approximately 1.2 and a Nakata index of approximately 100 mm2/m2 showed an uncomplicated follow-up, easily comparable with patients with larger PAs. No patients died, and no early takedown of the Fontan circulation had to be undertaken. Our results support the experience of Adachi and colleagues [7], who compared patients with Nakata indices down to a minimal 104 mm2/m2 vs patients with PAs sized approximately 300 mm2/m2 and found that even patients with a Nakata index of approximately 100 mm2/m2 had as good a recovery as their other patients [7]. In our study population, definitive univentricular palliation was done at a median age of 2 years. Age was considered above weight as cutoff criterion. Younger and lighter patients (aged < 24 months [n ¼ 18]; weight < 12 kg [n ¼ 63]) tended to have smaller PAs; however, this subset did not show a significantly poorer early outcome than their older and heavier companions. Ikai and colleagues [18] found in their study of 72 patients concerning the timing of the FO that the younger subsets experienced longer peritoneal drainage and a longer hospital stay. In our study, neither age nor weight showed significant influence on postoperative effusions and hospital length of stay. Even the smallest patient (7.68 kg at 16 months old) with fragile PA status (modified McGoon ratio, 0.8; modified Nakata index, 96.7 mm/m2) showed no adverse events and was discharged from the hospital after 12 uneventful postoperative days. These findings are in line with the recent reports of Sathanandam and colleagues [9] and Pizarro and colleagues [19], who stated that the FO can be performed safely and with favorable outcome in patients at or younger than 2 years of age and weighing less than 10 kg. The reason for an early FO is to eliminate the patient’s cyanosis and to relieve the single systemic ventricle from volume overload, which should preserve its function for a possibly long period [20–22]. The volume reduction is not a consequence of the FO per se but is secondary to avoidance of the collateral vessels development, which is usually stimulated by the long-standing cyanosis. Our general strategy is to close all sources of additional blood flow during the early-performed second-stage palliation (Glenn or hemi-FO). A remarkable finding that supports an early staging to preserve single ventricle function is mentioned in the publication of Baek and colleagues [22]. They could show in their study on late Fontan patients that in those where palliative procedures were left in place longer to promote PA growth and who had consequently the larger PAs had also significantly higher blood levels of brain natriuretic peptide. Because brain natriuretic peptide is a marker for excessive heart muscle stretching and from there for left ventricular dysfunction, the authors concluded that this may be indirect neurohumoral evidence for the adverse influence of late unloading on the future ventricular function. During their follow-up period since 1986, they could
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not find a disadvantage of small PAs on late functional outcome [22]. Ota and colleagues [20] furthermore pointed out that long-standing cyanosis and chronic volume overload, due to postponing the FO with hope that PAs will grow, could cause progressive ventricular fibrosis and impaired systolic and diastolic function [20]. These findings support our approach not to perform pre-Fontan PA augmentation procedures, including creation or leaving of aortopulmonary shunts during the second-stage procedure, even in patients with very small PAs, at the expense of an additional ventricular load. Of Choussat’s 10 commandments for a successful univentricular palliation, nowadays ventricular function and the status of the pulmonary vasculature seem to be the most concerning issues before the FO [9, 17, 21]. According to our results, smaller PA diameters measured using McGoon ratio and Nakata index do not adversely influence the Fontan palliation’s early outcome. Rapid staging in younger and smaller patients to preserve the single ventricle function is possible with good early results. In our opinion, there is no need to postpone the Fontan operation due to “smaller” PAs. The palliative procedures performed before FO to increase the size of the PAs at the expense of volume overload of the single ventricle and possible complications of prolonged cyanosis must be carefully weighed.
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