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Address for reprints: Sergio A. Carrillo, MD, Department of Cardiothoracic Surgery, Nationwide Children's Hospital and Division of Cardiac Surgery, The Ohio State University, 700 Children's Dr, Columbus, OH 43205.
Pulmonary artery reconstruction during comprehensive stage 2 (CS2) procedure can be challenging. Since 2017, we have employed preemptive left pulmonary artery (LPA) stenting. We hypothesized that LPA stenting promotes adequate growth and without compromising Fontan candidacy. Herewith, we report our midterm results.
Methods
From 2002 to 2020, 159 patients underwent CS2. Patients were divided as follows: no stent (n = 122; Group 1) and perioperative LPA stent (n = 37; Group 2). Group 2 was subdivided according to unplanned stent (n = 17; Group 2a) or preemptive stent (n = 20; Group 2b). Relevant perioperative data was reviewed. Nonparametric statistics were utilized.
Results
Median age and weight at surgery and hospital length of stay after CS2 did not differ between groups. Median cardiopulmonary bypass and crossclamp times were significantly greater in Group 1 (265 vs 243 minutes [P = .021] and 46 vs 26 minutes [P = .008]). In-hospital mortality was similar between Groups 1 and 2 (9.0% vs 18.9%, respectively [P = .1348]). Group 2b demonstrated a superior survival compared to Group 2a (P = .0335) but not Group 1 (P > .9999). Preemptive stenting significantly increased median hilar LPA diameter at CS2 exit angiogram compared with no stenting (P < .0001). Groups 2a and 2b significantly increased the pre-Fontan diameter of the hilar LPA when compared with Group 1 (6.1 and 6.8 vs 5.7 mm, respectively [P < .0001]). A further 120 patients underwent Fontan operation (75%). Median follow-up for Groups 1 and 2 were 7.4 and 3.0 years, respectively.
Conclusions
Perioperative LPA stenting during CS2 does not adversely affect pulmonary growth. Preemptive stenting seems advantageous for LPA growth in preparation for Fontan completion.
Preemptive stenting of the left pulmonary artery during comprehensive stage 2 palliation is a viable alternative to extensive surgical reconstruction without compromising Fontan candidacy.
The comprehensive stage 2 procedure has seen many modifications over the past decade. With the focus on optimization of pulmonary hemodynamics and architecture, the latest refinement is preemptive stenting of the left pulmonary artery. This has proven safe and feasible with promising medium-term results. While this has not compromised Fontan candidacy, long-term follow-up is necessary.
Hypoplastic left heart syndrome (HLHS) is among the most common critical congenital heart defects with roughly 1000 babies born every year with the diagnosis.
Due to the substantial morbidity and mortality that accompanied this procedure in the early years, an alternative form of surgical palliation combined with catheter-based therapies, was described in the 1990s.
Stenting of the arterial duct combined with banding of the pulmonary arteries and atrial septectomy or septostomy: a new approach to palliation for the hypoplastic left heart syndrome.
This hybrid stage 1 (HS1) palliation encompasses bilateral pulmonary artery (PA) banding, balloon atrial septostomy, and maintenance of ductal patency with stenting of the arterial duct, achieving the same physiological objectives as conventional therapy. There are many good reasons as to why HS1 might be employed over conventional techniques, perhaps chief amongst those is the avoidance of cardiopulmonary bypass (CPB) and complex arch reconstruction in a neonate with shunt physiology, thereby shifting the operative risk from the neonatal period to infancy (age 4-6 months).
Over time, with increased utilization, technical modifications and improved perioperative care, the HS1 strategy has transformed from a myth to accepted therapy,
The latest evolving strategy we have incorporated (routinely since 2017), is intraoperative, preemptive left pulmonary artery (LPA) stenting. We hypothesized that preemptive stenting may better protect the LPA from compression behind the reconstructed aortic arch thereby benefitting LPA growth and remodeling without any untoward hemodynamic consequences before Fontan completion. Herewith, we report our medium-term results with this newest technical innovation.
Patients and Methods
The Institutional Review Board of Nationwide Children's Hospital approved this study (No. 18-01166; approved November 2, 2018, updated October 24, 2021). Due to the retrospective nature of the study, informed consent was waived. We aimed to determine whether there would be any anatomic and/or physiological consequences of perioperative LPA stenting during CS2. During this perioperative period, we defined preemptive as stenting of the LPA independent of angiographic evaluation of vessel geometry during the conduct of CS2, before exit angiography. Similarly, unplanned was defined as LPA stenting occurring after exit angiography or at any point during the convalescence period before discharge. Lastly, the interstage period was defined as the time elapsed from CS2 discharge to completion of the Fontan stage.
The primary end points were to evaluate hemodynamic parameters and PA size as measured at the time of routine pre-Fontan cardiac catheterization. As it relates to PA size, 2 distinct points in time were selected for measurements. The first, during or following CS2 and the second, at the time of pre-Fontan cardiac catheterization. Different measures were obtained as follows: proximal right PA, interlobar right PA, proximal left PA, hilar left PA (hLPA), and interlobar left PA (Figure 1). Secondary end points included CS2 in-hospital mortality, Nakata index,
A new method for the quantitative standardization of cross-sectional areas of the pulmonary arteries in congenital heart disease with decreased pulmonary blood flow.
Figure 1Pre-Fontan angiography demonstrating site of pulmonary artery measurements at the anatomic regions of interest for the purpose of the study. A representative pre-Fontan angiography still picture from a patient from Group 1 (no stent). We selected 5 regions of interest for measurement throughout the pulmonary arterial tree: proximal right pulmonary artery (pRPA), interlobar right pulmonary artery (iRPA), proximal left pulmonary artery (pLPA), hilar left pulmonary artery (hLPA), and interlobar left pulmonary artery (iLPA). Comparable images and measurements were obtained at the time of comprehensive stage 2 exit and Pre-Fontan angiographies for each study subject on both groups.
A total of 260 patients underwent HS1 procedure within the study period (July 2002-June 2020). Excluded patients (n = 93) aside from those with perioperative and interstage deaths following HS1, were those receiving conventional stage 1, not progressing to and/or are waiting for CS2, with incomplete data, who underwent transplantation after HS1, or were lost to follow-up. The remaining 167 patients (64.23%) have completed CS2. An additional 8 patients were transplanted at some point following successful CS2 and not included in the final cohort. Reasons for transplantation included Fontan failure in 4 patients, pulmonary or aortic root thrombosis in 3 patients, and significant right ventricle dysfunction with severe tricuspid regurgitation in 1 patient. This left a total of 159 patients (61.15%) who are the focus of this study. These were divided as follows: Group 1 (no stent) and Group 2 (perioperative stent). The latter was subdivided in Group 2a (unplanned stent) and 2b (preemptive stent) (Figure E1).
Data Collection
The hospital charts, laboratory data, operative reports, catheterization results, and echocardiograms of these patients were carefully reviewed. Follow-up data were available for survivors was obtained from the electronic medical record, chart notes, outpatient clinic visits at our institution or from transmitted satellite clinic visits (eg, TeleHealth), as well as by direct patient contact.
All operative reports and relevant archived transthoracic and transesophageal echocardiographic images and cardiac catheterization cines were reviewed. Only preoperative complete echocardiogram studies closest to CS2 or Fontan were reviewed. As it relates to cardiac catheterization cines, all intraoperative and perioperative (following index surgery but within same hospital admission) studies of patients undergoing a CS2 were reviewed. Similarly, any interstage cardiac catheterization procedures were examined regardless of intent (hemodynamic or interventional and planned or unplanned). All patients underwent pre-Fontan cardiac catheterization at which time the Nakata index was calculated.
Operative Technique
The key technical aspects of both the HS1 and CS2 procedures remained unchanged throughout the study period and have been previously described.
Stenting of the arterial duct combined with banding of the pulmonary arteries and atrial septectomy or septostomy: a new approach to palliation for the hypoplastic left heart syndrome.
The management of the PA band site has been the focus of deliberate thought in search for the best outcomes, with different types of reconstruction and/or material used. The addition of intraoperative angiography at the completion of the procedure (exit angio) has been believed to provide an assurance of proper PA architecture following reconstruction. Early in our experience—before 2010— the most common cause of death was found to be secondary to PA thrombosis-related morbidity during the perioperative period. Insightful analysis of internal processes lead to an institutional shift toward the inception of a anticoagulation management protocol for all patients following CS2 with significant improvement in outcomes.
The use of intraoperative LPA stenting was first used in 2006 (as a salvage mode for some of the thrombosis-related cases) and then sparingly in the ensuing years. We also realized that stenting following exit angio, was technically cumbersome to complete, thus prolonging CPB and operating room time.
As a result of this internal protocol optimization, we have routinely incorporated preemptive stenting as part of the conduct of CS2 since 2017 (aside from the initial 2 cases that were performed in 2007 and 2009). Accordingly, after reentry sternotomy and institution of CPB, pulmonary runoff is controlled by clamping of the stented ductus arteriosus before all the pulmonary work is performed, whilst the heart beats. Once the PA bands are removed, both the stented ductus and pulmonary trunk are divided. The cardiac (proximal) PA stump is clamped. The site of previous LPA band is noted and dissection into the hilum beyond this point is not performed. The central PA remnant is spliced open in such a way to contour a native tissue patch, and the stented ductal remnant in the confluence of the PA is removed. The ensuing pulmonary defect is dealt with using autologous patch arterioplasty. Simultaneously, the interventional cardiology team sets and prepares the intravascular stent (16-mm mega LD mounted on a 6-mm balloon, Eve3, Medtronic), which is subsequently deployed under direct visualization aiming to leave the proximal end of the stent lying within the patch arterioplasty, whereas the distal part of the stent is left flush with the take-off of the left upper PA branch. The rest of the procedure is carried out in the usual fashion. An exit angiogram is performed during the rewarming phase (Figure 2, A-D) and after termination of CPB, the chest is closed in most instances. Extubation in the operating room at the conclusion of the procedure is typical (Video 1).
Figure 2Case study examples of the preemptive left pulmonary artery stenting technique. A, The comprehensive stage 2 (CS2) exit angiogram following completion of CS2, showing ideal intraoperative placement of a left pulmonary artery stent (yellow dashed outline) with normal arborization and perfusion of all lung segments. B, The pre-Fontan angiogram of the same patient. Interval growth of the branches can be seen with contrast in all major lobar, segmental and subsegmental pulmonary artery branches. C and D, Images of another patient undergoing preemptive stenting with similar pulmonary arterial bed appearance as the first patient.
A strict regimen of postoperative anticoagulation consisting of enoxaparin and aspirin is prescribed for 6 weeks. No additional PA imaging before stopping anticoagulation is obtained unless there is a clinical concern. The Fontan procedure is carried out in standard fashion. If any diameter irregularities between the Glenn and the stent are noted on the pre-Fontan catheterization these are addressed simultaneously with the construction of the Fontan pathway. The LPA stent has not posed additional technical challenges to the procedure and rarely has there been a need to cut across the stent during the Fontan operation.
Statistical Analysis
Results are reported as means ± SE or median and ranges where appropriate. The Shapiro-Wilk and D'Agostino-Pearson test were used to test the data for normality and informed selection of statistical methods. Categorical data were compared using Fisher exact test or Pearson χ2 test. Continuous data were analyzed using the Mann-Whitney U test or a 2-tailed t test. The probability of survival was determined using Kaplan-Meier analysis followed by Mantel-Cox log rank testing.
Results
Patient Demographic Characteristics and CS2 Outcomes
Median patient age and weight at the time of CS2 was 5.5 months (range, 2.1-18 months) and 6.2 kg (range, 3.5-9.9 kg), respectively. No significant differences in age and weight at the time of CS2 were found between groups (Table 1). CPB time was similar between groups (Group 1: 277.7 ± 58.4 minutes, Group 2: 259 ± 70.1 minutes). Preemptive stenting reduced CPB time by an average of 82 minutes when compared with unplanned stenting (Group 2a: 303.3 ± 74.2 minutes, Group 2b: 221.6 ± 37.9 minutes; P > .0001), and by an average of 56 minutes when compared with no stenting at all (P < .0001). Average aortic crossclamp time was shorter in patients who received perioperative stents compared with those who did not receive a stent (Group 1: 54.4 ± 48.5 minutes, Group 2: 30.9 ± 33.1 minutes; P = .0082). A shorter crossclamp time was also observed in the preemptive stenting group (21.5 ± 29.1 minutes; P = .0032). Deep hypothermic circulatory arrest times were similar between groups and only used sparingly.
Table 1Comprehensive stage 2 operative characteristics for entire cohort
Data not shown: Comparisons between groups 1 and 2 demonstrated a significantly reduced crossclamp time (P = .082) in Group 2. Similarly, comparisons between Group 1 and Group 2b revealed a significantly lower mean CPB time (P < .0001) and crossclamp time (P = .0031) in Group 2b.
Parameter
Group 1: No stent
Group 2: Stent
Group 2a: Unplanned
Group 2b: Preemptive
Weight (kg)
6.24 ± 1.18
6.42 ± 0.80
6.36 ± 0.63
6.47 ± 0.94
Age (m)
5.89 ± 1.83
5.55 ± 0.94
5.58 ± 0.97
5.58 ± 0.97
CBP time (min)
277.61 ± 58.41
259.14 ± 70.08
303.29 ± 74.24
221.60 ± 37.90
Crossclamp time (min)
54.35 ± 48.47
30.92 ± 33.14
42.06 ± 34.93
21.45 ± 29.12
DHCA time (min)
3.52 ± 13.82
7.92 ± 23.76
12.12 ± 28.03
4.35 ± 19.45
Length of stay (d)
23.53 ± 38.48
25.88 ± 28.48
34.8 ± 27.72
18.28 ± 27.52
Operative mortality
9.0 (11/122)
18.9 (7/37)
35.3 (6/17)
5 (1/20)
All continuous data are represented as mean ± SD. Mortality is reported as % deceased (n/N). CPB, Cardiopulmonary bypass; DHCA, deep hypothermic circulatory arrest.
∗ Data not shown: Comparisons between groups 1 and 2 demonstrated a significantly reduced crossclamp time (P = .082) in Group 2. Similarly, comparisons between Group 1 and Group 2b revealed a significantly lower mean CPB time (P < .0001) and crossclamp time (P = .0031) in Group 2b.
Hospital length of stay was unaffected by perioperative stent placement (Group 1: 23.5 ± 38.5 days, Group 2: 25.9 ± 28.5 days; P = .18); however, it was significantly shorter for Group 2b (18.3 ± 27.5 days; P = .0031). There was no appreciable difference in mortality between Group 1 and 2 (Group 1: 9.0% [11 out of 122], Group 2: 18.9% [7 out of 37]; P = .14). However, the preemptive stenting group had a statistically significant, lower in-hospital mortality than the unplanned stenting group (Group 2a: 35.3% [6 out of 17], Group 2b: 5% [1 out of 20]; P = .0335). No difference in mortality was observed between Group 1 and Group 2b.
CS2 to Fontan Completion Interstage Outcomes
The median interstage duration of the entire cohort was 2.0 years (range, 0.83-10 years). Perioperative stenting did not affect interstage duration. The proportion of catheter-based interventions during the interstage period was similar between groups (Group 1: 20.5%, Group 2: 21.6%) (Figure 3, A). All interstage interventions were reviewed and categorized as either isolated balloon angioplasty, primary endovascular stent placement, and repeat intervention (inclusive of any interstage intervention occurring following balloon angioplasty or stent placement). There were 31 interventions in 25 patients from Group 1 and 9 interventions in 8 patients from Group 2. The predominant type of intervention for each group differed. Predictively, in stented patients (Group 2) primary balloon angioplasty occurred more frequently than secondary stent implantation; whereas in the unstented cohort (Group 1), primary balloon angioplasty and primary stent placement occurred at similar frequency. Repeat intervention occurred nearly twice as often in the patients who did not receive a perioperative stent (no stent: 24%, stent: 12.5%) (Figure 3, B).
Figure 3Interstage intervention analysis between groups. A, The number of interstage interventions in each group. B, The distribution of interventions for both groups. Repeat intervention is defined as either repeat balloon angioplasty, stent dilatation, or placement of a secondary stent.
Pre-Fontan Angiographic and Hemodynamic Status Outcomes
Our primary outcome measures were cardiac hemodynamic status and angiographic quantification of LPA lumen diameter as measured at the routine preoperative angiographic study before Fontan surgery. First, we found a statistically significant difference between the hLPA diameter from the CS2 exit angiogram to pre-Fontan angiography in both groups (Group 1: CS2 exit 3.6 ± 1.2, pre-Fontan 5.8 ± 1.1 mm; P < .0001; Group 2: CS2 exit: 5.7 ± 1.5, pre-Fontan: 6.5 ± 0.9 mm; P < .0001, respectively) (Figure 4, A). In the preemptive stenting group, hLPA demonstrated not only a greater diameter at the CS2 exit time point compared with no stenting at all, but there was also an increased diameter of the hLPA measured at the pre-Fontan angiogram, suggesting intrinsic somatic LPA growth (CS2 exit 6.4 ± 0.4, pre-Fontan 6.8 ± 0.7 mm; P < .0001). Compared with Group 1, perioperative stenting yielded a greater hLPA diameter at the time of CS2 exit angiography (P < .0001) (Figure 4, B). Perhaps more importantly, perioperative stenting resulted in a significantly larger hLPA diameter (0.7 mm larger than Group 1) at the time of pre-Fontan angiography, inclusive of all interstage interventions (P < .0001). Further subanalyses showed that only preemptive stenting (and not unplanned) significantly increased hLPA diameter at both CS2 exit angio and pre-Fontan catheterization compared with Group 1 (Group 2b: CS2 exit: 6.4 ± 0.4, pre-Fontan: 6.8 ± 0.71 mm; Group 2a: CS2 exit: 6.0 ± 0.8, pre-Fontan: 6.1 ± 1; Group 1: CS2 exit 3.6 ± 1.2, pre-Fontan 5.8 ± 1.1 mm; P < .0001). Both unplanned and preemptive stenting yielded significantly greater hLPA diameters at the time of pre-Fontan angiography when compared with Group 1 (P < .0001).
Figure 4Box-and-whiskers plot demonstrating pulmonary artery measurement comparisons between groups. A, Hilar left pulmonary artery (LPA) diameters from Groups 1 and 2 at the time of comprehensive stage 2 (CS2) exit and pre-Fontan angiograms. B, Subanalysis of hilar LPA diameters from Groups 2a and 2b versus Group 1. For both panels, the lower and upper borders of the box represent the lower and upper quartiles (25th percentile and 75th percentile, respectively). The median is represented by the middle horizontal line. The lower and upper whiskers represent the minimum and maximum values of the data set. No outliers were observed.
Relevant hemodynamic parameters at pre-Fontan cardiac catheterization are listed in Table 2. There were no significant differences discovered between Group 1 versus Group 2, Group 2a versus Group 2b, and Group 1 versus Group 2b. The mean pre-Fontan Nakata index for Group 1 and 2 was 318.9 ± 102.9 mm2/m2 and 329.2 ± 97.2 mm2/m2, respectively. Group 2a had the lowest index at 296 ± 94.8 mm2/m2, whereas Group 2b had the greatest at 349.6 ± 95.6 mm2/m2.
Hypothesis led-multiple comparison testing yielded no statistically significant differences between groups.
Parameter
Group 1: No stent
Group 2: Stent
Group 2a: Unplanned
Group 2b: Preemptive
RA
6.1 ± 1.6
6.1 ± 1.2
6.1 ± 1.1
6.1 ± 1.3
RVEDP
7.9 ± 2.1
7.2 ± 1.2
7.1 ± 1.4
7.2 ± 1.2
LA
6.6 ± 1.8
6.7 ± 1.3
6.7 ± 0.8
6.6 ± 1.7
TPG
4.5 ± 1.2
4.5 ± 1.5
3.8 ± 1.4
5 ± 1.3
RPCWP
7.3 ± 1.9
7.1 ± 1.2
6.9 ± 0.6
7.3 ± 1.6
LPCWP
7.7 ± 1.8
9.5 ± 6.4
7.7 ± 0.6
11.1 ± 8.7
Arterial saturation (%)
82 ± 6
84 ± 4
84 ± 4
83 ± 4
Nakata index (mm2/m2)
318.9 ± 102.9
329.2 ± 97.21
296 ± 94.78
349.6 ± 95.56
All pressure measurements are provided in millimeters mercury. All continuous data are represented as mean ± SD. RA, Right atrium; RVDEP, right ventricular end-diastolic pressure; LA, left atrium; TPG, transpulmonary gradient; RPCWP, right pulmonary capillary wedge pressure; LPCWP, left pulmonary capillary wedge pressure.
∗ Hypothesis led-multiple comparison testing yielded no statistically significant differences between groups.
At the time of writing, 120 patients in the cohort had achieved Fontan status (75.47%). Fontan operative mortality was 0.8% (1 out of 120). Twenty-three patients from Group 2 have proceeded with Fontan, of which, 14 had a preemptive stent (Group 2b). Median follow-up for Group 1 and 2 was, 7.4 and 3.0 years, respectively, whereas for Group 2a and Group 2b was 7.0 and 2.4 years, respectively. Perioperative stenting did not significantly affect survival probability between Group 1 and Group 2 (hazard ratio [HR], 0.77; 95% CI, 0.31-1.91; P = .43) (Figure 5, A); however, survival comparison between Group 2a and 2b indicated that preemptive stenting affords a significantly greater probability of survival compared with unplanned stenting (HR, 7.01; 95% CI, 1.7-28.97 unplanned vs preemptive; P = .0071) (Figure 5, B). Similarly, Group 1 (no stent) had a significantly increased survival probability compared to Group 2a (unplanned stenting) (HR, 0.23; 95% CI, 0.007-0.76; P = .0158). No difference in survival was found between Group 1 and 2b (HR, 2.12; 95% CI, 0.61-7.41; P = .24). Finally, there have been no transplants on patients receiving a perioperative stent at latest follow-up.
Figure 5Kaplan-Meier survival analyses. A, Perioperative stenting (Group 2) did not significantly influence survival probability (P = .37) compared with no stent (Group 1). B, Preemptive stenting significantly increased survival probability when compared with unplanned stenting, although controlling for other factors was not included (P = .01). Preemptive stenting did not influence survival probability compared with no stenting (P = .27, not shown). CI, Confidence interval.
The discussion of merits versus weaknesses of the hybrid palliation strategy over the conventional (Norwood) pathway continue to evolve. Reported comparisons between the 2 diverging strategies focused mainly on operative and neurodevelopmental risk, with reports of similar outcomes between the 2.
As a result, in this study we closely examined the relationship between PA intervention during CS2 and candidacy for Fontan.
Our first experience with perioperative LPA stenting was in 2006 coinciding with the incorporation of routine exit angiography after completion of CS2. This type of reactionary stenting yielded mixed and often frustrating results hampered by persistent PA problems. We shifted then to preemptive stenting on the basis that stent implantation relieves obstruction while restoring balanced pulmonary blood distribution
coupled with the technical ease with which this could be performed, anticipating that successful stent implantation should promote distal vascular growth. To our knowledge, this is the first report describing preemptive PA stenting in the setting of CS2.
The choice of technique to address the band sites and concomitant PA reconstruction has seen many modifications,
have reported intraoperative preemptive balloon angioplasty (dilatation) in addition to patch arterioplasty of the PAs during CS2 utilizing a 6- to 8-mm balloon. Despite initial satisfactory results, they report a need for interstage catheter-based interventions, most commonly LPA stent implantation, in more than two-thirds of their cases. In contrast, in our study the incidence of interstage interventions (balloon angioplasty or stenting) for the entire cohort (n = 159) was 20.75%. This incidence is also lower than the 30% to 43% reported by Single Ventricle Reconstruction Trial group at 3 and 6 years for patients following the conventional Norwood procedure.
Unsurprisingly, the type of intervention depended on the PA strategy followed. Those in Group 1 (stentless during CS2) received more commonly primary stent implantation during the interstage period, whereas patients in Group 2 (perioperative stent during CS2) received more commonly balloon angioplasty. Only a small minority of patients (18% of those receiving any interstage intervention) underwent repeat interventions (Figure 3, B).
Fontan candidacy was not negatively influenced by perioperative stenting, contrary to the experience seen by other investigators.
Of the 159 patients who underwent CS2, 120 have achieved Fontan status (75.47%) with low perioperative mortality (<1%). A further 19 patients are awaiting the procedure. The hemodynamic parameters at the pre-Fontan catheterization yielded no statistically significant difference across the board, including arterial oxygen saturation and Nakata index. The preemptive group had the largest Nakata index of all the other groups at 349.2 mm2/m2, which is well above the threshold of 110 mm2/m2 described by Itatani and colleagues
below which patients undergoing the Fontan operation tend to have a lower long-term survival. A total of 14 out of 20 patients from the preemptive stent group have completed staged palliation with a median follow-up time of only 3 years, expectedly the lowest amongst groups, reflecting the chronology of CS2 optimization at our center.
We did not observe an adverse effect on the PAs with perioperative stenting (either unplanned or preemptive) with regard to Fontan candidacy. As expected, by nature of having a diameter to which the stent was ballooned, the CS2 exit angiogram on patients in Group 2 showed a greater interlobar right pulmonary artery and hLPA diameter compared with Group 1 (Table E1). This difference persisted, particularly in the region of the hLPA, to the pre-Fontan catheterization (Table E2). These results coupled with the hemodynamic measurements, indicate that perioperative stenting did not compromise Fontan candidacy following successful CS2. In fact, when considering only the hLPA diameter over time between groups we found a significantly greater diameter in Group 2 at the time of pre-Fontan catheterization. This suggests that stenting not only ensures a set nominal diameter of the LPA at CS2 and thus a larger cross-sectional area, but also promotes distal growth comparable, and at times greater, than in Group 1 (Figure 4,A). A larger cross-sectional area provides ideal Fontan hemodynamics while minimizing energy loss and maximizing cardiac index.
With the results of this analysis, we have moved to a liberal consideration of preemptive LPA stent implantation during CS2, particularly and especially, when confronted with a challenging PA bed. We have seen that this proactive strategy in the perioperative setting has yielded better clinical results over an unplanned, oft-reactionary strategy (odds ratio, 10.36; 95% CI, 1.216-124.0; P .05 for unplanned stent vs preemptive), although it still remains unclear and unproven that this risk reduction is a consequence of preemptive stenting alone.
Limitations
A major limitation of this study was its retrospective and nonrandomized nature. Single-institutional experience and lack of a conventional stage 1 group made comparison between strategies difficult. The effects of era and other programmatic changes were not accounted for. Moreover, pulmonary blood flow balance and differential was not evaluated in this study because cardiac magnetic resonance and/other nuclear imaging post-LPA stent is not routine practice. Although data regarding pre-Fontan candidacy and subsequent Fontan outcome are presented herewith, it may still not represent the overall picture of the fate of the PAs following a hybrid palliation and therefore further follow-up studies, including a randomized trial, are necessary.
Conclusions
Perioperative LPA stenting during CS2 does not adversely affect PA growth allowing progression to the Fontan procedure in most patients. In our study, a planned, preemptive strategy yielded the best result with low perioperative morbidity and mortality. However, follow-up is necessary to identify those who would benefit the most and understand potential long-term consequences of this novel but controversial technique. Figure 6 provides a visual summary of the study and Figure 7 is a visual summary of the surgical technique.
Figure 6Visual summary and take-home messages of the study. CS2, Comprehensive stage 2; CPB, cardiopulmonary bypass; XC, crossclamp; LPA, left pulmonary artery; CI, confidence interval.
Figure 7Resultant angiographic image following preemptive stenting of the left pulmonary artery (LPA) during comprehensive stage 2 operation mounted stent in balloon catheter shown in blue.
The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest.
Multiple t tests with Holm-Sidak's correction indicate the likelihood of difference between groups for the prespecified regions of interest at each censoring point.
Region of interest
Group 1: No stent
Group 2: Stent
P value
CS2 exit
pRPA
4.10 ± 1.40
4.20 ± 1.20
.70
iRPA
4.70 ± 1.60
5.60 ± 1.40
.013
pLPA
5.70 ± 1.50
6.50 ± 1.80
.07
hLPA
3.60 ± 1.10
6.20 ± 0.60
<.000001
iLPA
5.50 ± 1.70
6.20 ± 1.60
.07
Pre-Fontan
pRPA
7.70 ± 1.60
7.90 ± 1.70
.88
iRPA
8.50 ± 9.40
7.70 ± 1.60
.85
pLPA
6.80 ± 1.10
6.70 ± 1.10
.87
hLPA
5.80 ± 1.10
6.40 ± 0.80
.005
iLPA
6.20 ± 1.30
5.90 ± 0.90
.47
All diameter measurements are provided in millimeters and are represented as mean ± SD. Bold values indicates statistical significance. CS2, Comprehensive stage 2; pRPA, proximal right pulmonary artery; iRPA, interlobar right pulmonary artery; pLPA, proximal left pulmonary artery; hLPA, hilar left pulmonary artery; iLPA, interlobar left pulmonary artery.
∗ Multiple t tests with Holm-Sidak's correction indicate the likelihood of difference between groups for the prespecified regions of interest at each censoring point.
Multiple t tests with Holm-Sidak's correction indicate the likelihood of difference over time for a given region of interest within each group.
Region of interest
CS2 exit
Pre-Fontan
P value
Group 1: No stent
pRPA
4.10 ± 1.40
7.70 ± 1.60
<.000001
iRPA
4.70 ± 1.60
8.50 ± 9.40
.001
pLPA
5.70 ± 1.50
6.80 ± 1.10
.000001
hLPA
3.60 ± 1.10
5.80 ± 1.10
<.000001
iLPA
5.50 ± 1.70
6.20 ± 1.30
.0032
Group 2: Stent
pRPA
4.20 ± 1.20
7.90 ± 1.70
<.000001
iRPA
5.60 ± 1.40
7.70 ± 1.60
.00031
pLPA
6.50 ± 1.80
6.70 ± 1.10
.57
hLPA
6.20 ± 0.60
6.40 ± 0.80
.55
iLPA
6.20 ± 1.60
5.90 ± 0.90
.56
All diameter measurements are provided in millimeters and are represented as mean ± SD. Bold values indicates statistical significance. CS2,Comprehensive stage 2;pRPA, proximal right pulmonary artery; iRPA, interlobar right pulmonary artery; pLPA, proximal left pulmonary artery; hLPA, hilar left pulmonary artery; iLPA, interlobar left pulmonary artery.
∗ Multiple t tests with Holm-Sidak's correction indicate the likelihood of difference over time for a given region of interest within each group.
Stenting of the arterial duct combined with banding of the pulmonary arteries and atrial septectomy or septostomy: a new approach to palliation for the hypoplastic left heart syndrome.
A new method for the quantitative standardization of cross-sectional areas of the pulmonary arteries in congenital heart disease with decreased pulmonary blood flow.
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