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Outcomes After Bidirectional Glenn Operation: Blalock-Taussig Shunt Versus Right Ventricle–to–Pulmonary Artery Conduit
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PEDIATRIC CARDIAC SURGERY: The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org. To take the CME activity related to this article, you must have either an STS member or an individual nonmember subscription to the journal.
Outcomes After Bidirectional Glenn Operation: Blalock-Taussig Shunt Versus Right Ventricle–to–Pulmonary Artery Conduit Lillian Lai, MHA, MD, Peter C. Laussen, MBBS, Clifford L. Cua, MD, David L. Wessel, MD, John M. Costello, MD, Pedro J. del Nido, MD, John E. Mayer, MD, and Ravi R. Thiagarajan, MBBS, MPH Departments of Cardiology and Cardiac Surgery, Children’s Hospital Boston; and Departments of Pediatrics and Surgery, Harvard Medical School, Boston, Massachusetts
Background. There are distinct physiologic differences between patients with single-ventricle lesions who have undergone the Norwood procedure with a right ventricle– to–pulmonary artery conduit (NW-RVPA) compared with those patients who have undergone the Norwood operation with a Blalock-Taussig shunt (NW-BTS). We evaluated bidirectional Glenn operation outcomes and compared the two groups to assess whether the type of Norwood operation influenced outcomes. Methods. A retrospective chart review compared bidirectional Glenn operation outcomes for children undergoing the Norwood operation with NW-RVPA or NWBTS at Children’s Hospital Boston from January 1, 2002, to December 31, 2003. Results. Of 80 patients undergoing the Norwood operation, 56 (NW-BTS, 27 versus NW-RVPA, 29) returned for
the bidirectional Glenn operation at our institution. The NW-RVPA group had a lower median age at presentation for bidirectional Glenn (4.5 months versus 5.8 months; p ⴝ 0.01), but had better weight gain (20.6 g/day versus 16.5 g/day; p ⴝ 0.03) than the NW-BTS group. No interstage deaths occurred in the NW-RVPA group. There were no differences in morbidity or mortality after the BDG between the two groups. Conclusions. There were no differences in morbidity and mortality outcomes after the bidirectional Glenn operation between the NW-RVPA and NW-BTS groups. Despite younger age at presentation, the NW-RVPA patients had better growth rate, which may have contributed to the similar postoperative outcomes. (Ann Thorac Surg 2007;83:1768 –73) © 2007 by The Society of Thoracic Surgeons
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The purpose of this study was to compare the interstage outcomes and the outcomes after the BDG in singleventricle patients who had previously undergone the NWRVPA or NW-BTS procedures for stage I palliation.
he Norwood operation, in which a right ventricle–to– pulmonary artery conduit (NW-RVPA) is used to provide pulmonary blood flow in patients with single-ventricle physiology, has been widely adopted after reports of improved hospital and interstage mortality compared with the Norwood operation, where pulmonary blood flow is provided by using a modified Blalock-Taussig shunt (NW-BTS) [1–13]. Factors cited for improved early and interstage survival after the NW-RVPA include higher diastolic pressures, improved coronary and vital organ perfusion, and decreased volume load to the single ventricle owing to a better balance of pulmonary and systemic circulation [1–11]. Despite these distinct differences in hospital and interstage outcomes between these groups, limited information is available about how the type of Norwood operation affects outcomes after the second-stage bidirectional Glenn operation (BDG).
Accepted for publication Nov 22, 2006. Address correspondence to Dr Lai, 401 Smyth Rd, Ottawa, Ontario 2B5, Canada; e-mail: [email protected].
© 2007 by The Society of Thoracic Surgeons Published by Elsevier Inc
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Material and Methods The Committee for Clinical Research at Children’s Hospital Boston, Boston, Massachusetts, approved the retrospective review of patient medical records and also waived the need for patient (parental) consent for the study. Study subjects were selected from a cohort of patients who underwent single-ventricle palliation with the Norwood operation between January 1, 2002, and December 31, 2003 (Fig 1). During this 2-year period, both the NW-RVPA and NWBTS procedures were performed in our institution, and the choice of Norwood operation type was left to the discretion of the surgeon [14]. Technical details of the Norwood operation and early postoperative outcomes in this cohort with hypoplastic left heart syndrome (HLHS) have been previously reported [14]. 0003-4975/07/$32.00 doi:10.1016/j.athoracsur.2006.11.076
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Table 2. Interstage Outcomesa Outcome Duration of interstage period (days) Interstage hospital admission Reason for interstage admission Cyanosis Other reasons Urgent catheterization Urgent surgery Need for gastrostomy tube Weight at BDG (kg) Rate of weight gain (g/day)
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
146 (26–282)
109 (47–244)
0.02
10 (37%)
11 (37%)
0.95
2 8 9 5 6
9 2 8 3 1
0.01
5.6 (3.8–9.3) 16.5 (10–60)
5.5 (3.3–6.6) 20.6 (10–40)
0.50 0.03
1.0 0.7 0.05
a Categoric data are presented as numbers (percentage) and continuous data as median (range).
BDG ⫽ bidirectional Glenn; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-pulmonary artery shunt.
Fig 1. Study population (BT ⫽ Blalock-Taussig; RV-PA, right ventricle-pulmonary artery).
Patients Only patients from this cohort who underwent the BDG operation at our institution were included in the study to prevent bias introduced by the variability in clinical practice between different institutions. Our institutional practice for Table 1. Demographics of the Study Populationa
Male Age at BDG (mo) Weight (kg) Diagnoses HLHS Non-HLHS DORV-MA DILV Congenital AS/Shone syndrome Shunt size and conduit size 3.5 mm 4.0 mm 5.0 mm
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
14 (52%) 5.8 (2.0–10.1) 5.6 (3.8–9.3)
17 (59%) 4.5 (2.2–8.9) 5.5 (3.3–6.6)
0.61 0.01 0.50
24 (87%) 3 (13%) 2 0 1
26 (90%) 3 (10%) 1 1 1
1.0
27 2 27
a
Categoric data are presented as number (percentage) and continuous data as median (range). AS ⫽ aortic stenosis; BDG ⫽ bidirectional Glenn operation; DILV ⫽ double inlet left ventricle; DORV ⫽ double outlet right ventricle; HLHS ⫽ hypoplastic left heart syndrome; MA ⫽ mitral atresia; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-pulmonary artery conduit.
palliation of a patient with single-ventricle lesions after the Norwood operation typically includes the performance of a cardiac catheterization at 4 to 5 months of age to determine candidacy for the BDG, which is performed at approximately 6 months of age. Some patients in our cohort participated in a randomized controlled trial in which the usefulness of magnetic resonance imaging (MRI) was compared with cardiac catheterization for pre-BDG assessment. Thus, some patients received an MRI rather than a cardiac catheterization or both. Data on patient demographics, diagnoses, interstage admissions, preoperative, intraoperative, and postoperative BDG hemodynamic and outcome were collected. We defined the interstage period as the time from hospital discharge after the Norwood operation until the time of the BDG operation. Interstage admission was defined as hospital admission for purposes other than a routine diagnostic cardiac catheterization before the BDG operation or a scheduled BDG procedure. Urgent catheterization was defined as a diagnostic or interventional cardiac catheterization procedure performed on a patient who required interstage admission, and urgent operation was defined as a BDG or other cardiac operative procedure performed in a patient who required interstage hospital admission and needed a cardiac operation before discharge.
Statistical Analysis Continuous data were compared using the Mann Whitney U test, and categoric data were compared using the 2 test. The Fisher exact test was used when the expected value in any category was ⬍5. Postoperative hemodynamic variables and inotrope scores were collected at 6-hour intervals and averaged over 12 intervals for the first 24 hours and compared with baseline values collected on admission to the cardiac
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LAI ET AL GLENN OUTCOMES AFTER NORWOOD OPERATION
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Results Study Population Of 80 patients undergoing a Norwood operation (NWBTS, 46; NW-RVPA, 34) for stage 1 of single-ventricle palliation during the study period, 56 patients (NW-BTS, 27 [48%]; NW-RVPA, 29 [52%]) returned to our institution for the BDG operation and comprised our study population (Fig 1.) Demographic data of the study population are summarized in Table 1.
Interstage Outcomes and Growth
Fig 2. Age at bidirectional Glenn operation between the Norwood and Blalock-Taussig (NW-BT) group (solid line) and the Norwood and the right ventricle–to–pulmonary artery (NW-RVPA) group (dashed line).
intensive care unit using the repeated measures analysis of variance. The inotrope score was calculated using the formula modified from Wernoversusky and colleagues [14, 15]. Kaplan-Meier survival analysis and the log-rank test were used to compare time to BDG operation after hospital discharge following the Norwood operation and age at BDG between the two surgical groups. Statistical significance was set at a p ⱕ 0.05. Data analysis was performed using SPSS 13.0 statistical software (SPSS Inc, Chicago, IL). Continuous data are reported as median values with ranges, unless specified otherwise.
During the interstage period, no deaths occurred in the NW-RVPA group; however, 6 patients died in the NW-BTS group. No significant difference was found between the two groups with respect to the overall number of interstage hospital admissions, but there was a difference in the reason for admission (Table 2). Cyanosis was the most frequent reason for interstage hospital admission in patients in the NWRVPA group compared with the NW-BTS group (9 versus 2; p ⫽ 0.01), whereas reasons other than cyanosis were more common in the NW-BTS group (8 versus 2; Fischer exact p ⫽ 0.01). These included cardiac failure in 6 patients and intercurrent viral illness in 2 in the NW-BTS group, and 1 patient each in the NW-RVPA group with surgical wound infection and poor feeding. Among patients needing interstage hospital admission (NW-BTS 10, NW-RVPA 11), 6 (22%) of 27 patients in the NW-BTS group and 5 (17%) of 29 in the NW-RVPA group needed management in the cardiac intensive care unit (CICU) during their hospitalization. No significant difference was found in the number of patients needing urgent cardiac catheterizations or urgent surgical intervention between the two groups (Table 2). Of the 9 patients in the NW-BTS group who needed urgent cardiac catheterization, 5 needed an intervention during the catheterization. Catheter-based interventions in this group
Table 3. Hemodynamic Assessment Before Bidirectional Glenn Operation NW-BTS (n ⫽ 27) Echocardiographic assessment Moderate or severe RV dysfunction Moderate or severe TV regurgitation Cardiac catheterization assessmentb Patients undergoing catheterization (n) Cardiac index (L/min/m2) RV end-diastolic pressure (mm Hg) Diastolic blood pressure (mm Hg) Mean pulmonary artery pressure (mm Hg) Systemic oxygen saturation (%) Hematocrit (%) Qp:Qs Pulmonary vascular resistance (U · m2) Patients requiring catheter based intervention Magnetic Resonance Image (n) a
NW-RVPA (n ⫽ 29)
1 (4) 7 (26)
3 (10) 4 (16)
22 (81) 3.0 (1.7–5.8) 10 (4–18) 41 (25–59) 17 (10–28) 77 (67–90) 45 (34–63) 1.2 (0.6–3.0) 1.9 (0.6–5.0) 14 (70) 6 (22)
Categoric data presented as number (percentage) and continuous data as median (range). non-urgent catheterization.
22 (76) 3.1 (1.9–5.5) 9 (4–14) 50 (29–84) 16 (10–23) 75 (62–87) 48 (36–62) 0.95 (.4–1.8) 2.0 (0.8–3.2) 11 (68) 8 (28) b
p Value 0.61 0.25
0.63 0.56 0.004 0.31 0.06 0.20 0.04 0.90 1.0 0.64
Includes data from patients undergoing urgent and
NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-pulmonary artery shunt; Qp:Qs ⫽ ratio of pulmonary to systemic blood flow; RV ⫽ right ventricle; TV ⫽ tricuspid value.
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Table 4. Intraoperative Data After the Bidirectional Glenn Operationa Variable Total pump time (min) Patients needing circulatory arrest (n) Circulatory arrest time (min) Post-CPB lactate level Other procedures with BDG Pulmonary artery enlargement ASD enlargement Tricuspid valve repair
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
65 (47–257) 2 (7)
69 (47–131) 9 (31)
0.50 0.03
12 (1–20)
0.15
1.8 (0.7–7.2) 9 (31)
0.91 0.85
26.5 (17–36) 1.7 (1.2–5.8) 9 (33) 5 (19)
6 (21)
0.84
3 (11) 2 (7)
0 3 (10)
0.11 1.0
a Categoric data presented as number (percentage) and continuous data as median (range).
ASD ⫽ atrial septal defect; BDG ⫽ bidirectional Glenn; CPB ⫽ cardio pulmonary bypass; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-artery conduit.
included dilation of obstruction at the distal aortic arch in 4 patients, and dilation of narrowing in the innominate artery proximal to the insertion of arterial end of the BlalockTaussig shunt in 1. Among the 8 patients in the NW-RVPA group who needed urgent cardiac catheterization, 6 needed interventions. Catheter based interventions included enlargement of atrial communication in 2, dilation and stenting of the right ventricle to pulmonary artery conduit in 1, and a restrictive bulboventricular foramen in another. Two patients in the NW-RVPA group had dilation of obstruction at the distal aortic arch.
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Of the total eight patients requiring urgent surgical intervention after interstage hospital admission (NW-BTS, 5; NW-RVPA, 3), 7 had early BDG operations. One patient from the NW-RVPA group (double inlet left ventricle) had the RVPA conduit placed between the bulboventricular foramen (ie, the attenuated right ventricle) and the main pulmonary artery as a part of the NW-RVPA operation. This patient was readmitted to the hospital for severe cyanosis and had urgent cardiac catheterization that revealed narrowing of the bulboventricular foramen from where the RVPA conduit arose. A 4.0-mm intravascular stent (Express-2, Boston Scientific, Boston, MA) was placed across the narrowed bulboventricular foramen, with improvement of oxygen saturations. Severe cyanosis recurred 2 months after the procedure despite redilation of the intravascular stent. As a result, the patient was converted to a NW-BTS. This patient is included in the NW-RVPA group for analysis. The interstage period was significantly shorter in the NW-RVPA group than in the NW-BTS group, with a median time to BDG of 109 days (range, 47 to 244 days) versus 146 days (range, 26 to 282 days; log-rank p ⫽ 0.02). As a result, patients in the NW-RVPA group were significantly younger compared with the NW-BTS group, with a median age of 4.5 months (range, 2.2 to 8.9 months) versus 5.8 months (range, 2.0 to 10.1 months; log-rank p ⫽ 0.01; Fig 2). Of the 7 patients who required gastrostomy tube placement, 6 (22%) were in the NW-BTS and 1 (3%) was in the NW-RVPA group (Fisher exact p ⫽ 0.05; Table 2). Patients in the NW-RVPA group gained significantly more weight during the interstage period compared with the NW-BTS group (20.6 g/d versus 16.5 g/d; p ⫽ 0.03). As a result, although the NW-RVPA group was younger, there was no difference in body weight compared with the NW-BTS group at the time of the BDG operation (Table 2).
Table 5. Postoperative Hemodynamics During the First 24 Hours Variable Heart rate (beats/min) Mean arterial blood pressure (mm Hg) Left atrial pressure (mm Hg)a SVC (mm Hg)b Sao2 (%) Pao2 (mm Hg) Pao2/Fio2 Inotrope score
a
Group
Baseline
1–12 hr
13–24 hr
p Value
NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA
142 ⫾ 22 146 ⫾ 23 68 ⫾ 9 62 ⫾ 7 9⫾3 9⫾3 17 ⫾ 3 17 ⫾ 2 87 ⫾ 11 83 ⫾ 9 50 ⫾ 15 47 ⫾ 9 53 ⫾ 8 49 ⫾ 11 6⫾3 5⫾3
132 ⫾ 15 126 ⫾ 18 73 ⫾ 9 70 ⫾ 7 8⫾3 9⫾3 15 ⫾ 4 16 ⫾ 3 78 ⫾ 6 79 ⫾ 5 45 ⫾ 8 42 ⫾ 5 105 ⫾ 32 103 ⫾ 33 8⫾3 6⫾3
118 ⫾ 13 119 ⫾ 18 74 ⫾ 9 74 ⫾ 8 8⫾2 10 ⫾ 4 13 ⫾ 3 17 ⫾ 5 80 ⫾ 6 79 ⫾ 5 43 ⫾ 5 42 ⫾ 4 152 ⫾ 62 149 ⫾ 46 6⫾3 5⫾3
0.17
Left atrial pressure: observations: NW-BTS: n ⫽ 24, NW-RVPA group: n ⫽ 21.
b
0.09 0.56 0.05 0.08 0.51 0.98 0.50
SVC pressure: observations NW-BTS: n ⫽ 11, NWRV-PA: n ⫽ 18.
Fio2 ⫽ fraction of inspired oxygen; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-artery conduit; Pao2 ⫽ partial pressure of oxygen in arterial blood; Sao2 ⫽ peripheral oxygen saturation; SVC ⫽ superior vena cava.
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LAI ET AL GLENN OUTCOMES AFTER NORWOOD OPERATION
Table 6. Postoperative Outcomes After Bidirectional Glenn Operationa Variable Delayed sternum closure Inhaled nitric oxide use Nosocomial infectionb Pleural effusion Duration of ventilation (hr) Duration of CICU stay (days) Duration of hospital stay (days)
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
1 (4) 3 (11) 0 2 (8) 13.5 (6–98)
0 1 (3) 3 (10) 2 (7) 17 (6.5–156)
0.48 0.34 0.23 1.0 0.59
2 (1–10)
2 (1–26)
0.28
6 (3–26)
6 (3–64)
0.77
a Categoric data presented as numbers (percentage), continuous data as b median (range). Nosocomial infection includes blood stream and sternal wound infection.
CICU ⫽ cardiac intensive care unit; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-artery conduit.
Pre-Bidirectional Glenn Assessment Pre-BDG hemodynamic assessment (Table 3) showed significantly lower diastolic blood pressure and a higher pulmonary–systemic blood flow ratio in the NW-BTS group. Intraoperative variables were similar (Table 4). Postoperative outcomes (Table 5 and 6) showed that the superior vena cava (SVC) pressure decreased over time from baseline for the NW-BTS group compared with the NW-RVPA group, where SVC pressure tended to stay the same compared with the baseline. For the whole cohort, the 12 patients who required BDG when they were younger than 4 months old needed a longer duration of ventilation (22.3 hours [range, 8.5 to 156 hours] versus 14.3 hours [range, 6 to 98 hours], p ⫽ 0.002), had longer stays both in the CICU (3 days [range, 1 to 26 days] versus 2 days [range, 1 to 15 days]; p ⫽ 0.006) and in the hospital (10.5 days [range, 5 to 47 days] versus 5 days [range, 3 to 64 days]; p ⫽ 0.002) compared with those patients who underwent BDG at 4 months old or older. The available follow-up time after discharge after the BDG operation was longer for the NW-BTS group (1.64 years [range, 0 to 3.1 years] versus 0.6 years [range, 0 to 2.3 years]; p ⬍ 0.001). The 12-month survival after BDG was not significantly different for the two operative groups. One patient in the NW-BTS group required cardiac transplantation for persistent cardiac failure and cyanosis, and 2 in the NW-RVPA group died from cardiac failure refractory to medical therapy.
Comment In our cohort of patients undergoing the Norwood operation, patients in the NW-RVPA group underwent the BDG operation at a significantly younger age than the NW-BTS group but had similar outcomes compared with the older NW-BTS group. An important finding in our comparison of the two surgical groups is the better weight gain seen in the NW-RVPA group during the
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interstage period resulting in equal weights at time of presentation for BDG despite a significantly younger age. Although we did not compare daily caloric intake among patients in the two groups, we speculate better somatic growth in the NW-RVPA group based on advantages in their circulatory physiology compared with the NW-BTS group, as detailed in several reports [1, 5, 9, 11, 13]. After the NW-RVPA operation, there is theoretically a better balance of pulmonary and systemic circulation compared with the NW-BTS group because of the absence of diastolic steal into the pulmonary circulation from the BTS. This improves diastolic blood pressure, which in turn allows for better end-organ perfusion, including earlier mesenteric perfusion. With better gut perfusion and less pulmonary overcirculation, one would suspect better weight gain owing to less congestive heart failure and thus fewer feeding difficulties. This may also explain the relatively lower rates of admissions for viral illness and cardiac failure in the NW-RVPA group. Although single-ventricle volume loading may be present after the NW-RVPA procedure owing to regurgitation from the nonvalved right ventricle–to–pulmonary artery conduit, volume load in the NW-BTS procedure may be larger because of the larger fraction of pulmonary blood flow frequently seen in this type of circulation. Cua and colleagues [14] previously reported from this cohort of single-ventricle patients undergoing the Norwood operation that those patients with HLHS who underwent the NW-BTS took longer to establish enteral feeds compared with the NW-RVPA group. In this follow-up study, we found that significantly more NW-BTS patients required gastrostomy tubes to aid with feeding and calorie supplementation during the interstage period. Despite this help, their growth rate was still lower than that in the NW-RVPA group. Their poor growth may be due to increased basal metabolic energy requirements as well as poor nutrient absorption caused by the disadvantages in the NW-BTS circulatory physiology [16 –19]. Previous reports have shown that younger age may be a risk factor for mortality after the BDG operation [20, 21]. In a 2004 report, Jaquiss and colleagues [20] compared the effect of age on outcome for infants with HLHS undergoing the BDG operation. Of the 85 patients they studied, 33 underwent BDG operation when they were younger than 4 months old. Similar to the report by Jaquiss and colleagues, our cohort of patients undergoing BDG operation before they were 4 months old had a comparatively longer duration of mechanical ventilation, CICU stay, and average length of stay compared with those aged older than 4 months. They concluded that patients undergoing BDG operation at younger than 4 months of age consumed more resources than older patients but that it was safe to perform the BDG at this young age. We saw no difference in outcomes overall between the two groups, despite the fact that the RVPA group presented at a significantly younger age compared with the BTS group (4.5 months versus 5.5 months, p ⫽ 0.01). A possible explanation is that the two groups had a similar number of patients who presented before they were 4 months old for the BDG operation (5/27 BTS [19%] versus 7/29 RVPA
[24%], p ⫽ 0.6), or that better health status and weight gain in the interstage period for the younger RVPA group may have resulted in outcomes similar to the older BTS group. A small number of patients in our cohort had intravascular catheters placed in the SVC allowing measurement of pressure in the Glenn pathway. This pressure was significantly higher and remained elevated in the NWRVPA group compared with the NW-BTS group during the first postoperative day, despite having similar pulmonary artery pressures, pulmonary vascular resistance, and right ventricular end-diastolic pressures documented on their preoperative BDG catheterizations. This finding could suggest a restriction to BDG pathway flow, possibly from anatomically smaller pulmonary arteries or higher postoperative pulmonary vascular resistance, or an early manifestation of diastolic dysfunction caused by the ventriculotomy in the NW-RVPA group. A few small studies have suggested better systolic function in the RVPA group [7, 22, 23]; however, the long-term effects of performing a right ventriculotomy to place the RVPA in neonates are unknown. Absence of differences in oxygenation, pleural drainage, and overall outcomes between the two surgical groups suggests that the persistently higher BDG pathway pressure in the NW-RVPA group did not affect clinical outcomes. Our study is limited by its small sample size, retrospective nature, and lack of standardization in management; therefore, our results should be interpreted cautiously. However, patients for the two operative groups were managed during a concurrent time period and thus both groups were subject to similar decision-making processes for proceeding to the BDG operation and postoperative management. The choice of surgical intervention rather than one based on cardiac catheterization for management of early and persistent cyanosis in this cohort of patients, and the type of surgery, such as BDG or conversion to the NW-BTS arrangement in our report, may also be specific to our institution. In conclusion, our study shows that the NW-RVPA group presented at a significantly younger age for their BDG compared with the NW-BTS group, but there was no difference in post-BDG outcomes. We speculate this may be due to better growth rate in the interstage period in the NW-RVPA group compared with the NW-BTS group.
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5. Maher KO, Pizarro C, Gidding SS, et al. Hemodynamic profile after the Norwood procedure with right ventricle to pulmonary artery conduit. Circulation 2003;108:782– 4. 6. Mahle WT, Cuadrado AR, Tam VK. Early experience with a modified Norwood procedure using right ventricle to pulmonary artery conduit. Ann Thorac Surg 2003;76:1084 – 8. 7. Mair R, Tulzer G, Sames E, et al. Right ventricular to pulmonary artery conduit instead of modified BlalockTaussig shunt improves postoperative hemodynamics in newborns after the Norwood operation. J Thorac Cardiovasc Surg 2003;126:1378 – 84. 8. Malec E, Januszewska K, Kolz J, Pajak J. Factors influencing early outcome of Norwood procedure for hypoplastic left heart syndrome. Eur J Cardiothorac Surg 2000;18:202– 6. 9. Malec E, Januszewska K, Kolcz J, Mroczek T. Right ventricleto-pulmonary artery shunt versus modified Blalock-Taussig shunt in the Norwood procedure for hypoplastic left heart syndrome – influence on early and late haemodynamic status. Eur J Cardiothorac Surg 2003;23:728 –33. 10. Pizarro C, Norwood WI. Right ventricle to pulmonary artery conduit has a favorable impact on postoperative physiology after stage I Norwood: preliminary results. Eur J Cardiothorac Surg 2003;23:991–5. 11. Sano S, Ishino K, Kado H, et al. Outcome of right ventricleto-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome: a multi-institutional study. Ann Thorac Surg 2004;78:1951– 8. 12. Cua CL, Thiagarajan RR, Taeed R, et al. Improved interstage mortality with the modified Norwood procedure: a metaanalysis. Ann Thorac Surg 2005;80:44 –9. 13. Tabbutt S, Dominguez TE, Ravishankar C, et al. Outcomes after the stage I reconstruction comparing the right ventricular to pulmonary artery conduit with the modified Blalock Taussig Shunt. Ann Thorac Surg 2005;80:1582–90. 14. Cua CL, Thiagarajan RR, Gauvreau K, et al. Early postoperative outcomes in a series of infants with hypoplastic left heart syndrome undergoing stage I palliation operation with either modified Blalock-Taussig shunt or right ventricle to pulmonary artery conduit. Pediatr Crit Care Med 2006;7:238 – 44. 15. Wernoversusky G, Wypij D, Jonas RA, et al. Postoperative course and hemodynamic profile after the arterial switch operation in neonates and infants. A comparison of low-flow cardiopulmonary bypass and circulatory arrest. Circulation 1995;92:2226–35. 16. Kelleher DK, Laussen P, Teixeira-Pinto A, Duggan C. Growth and correlates of nutritional status among infants with hypoplastic left heart syndrome (HLHS) after stage 1 Norwood procedure. Nutrition 2006;22:237– 44. 17. Jeffries HE, Wells WJ, Starnes VA, Wetzel RC, Moromisato DY. Gastrointestinal morbidity after Norwood palliation for hypoplastic left heart syndrome. Ann Thorac Surg 2006;81:982–7. 18. del Castillo SL, Moromisato DY, Dorey F, et al. Mesenteric blood flow velocities in the newborn with single-ventricle physiology: modified Blalock-Taussig shunt versus right ventricle-pulmonary artery conduit. Pediatr Crit Care Med 2006;7:132–7. 19. Malagon I, Onkenhout W, Klok M, van der Poel PF, Bovill JG, Hazekamp MG. Gut permeability in neonates after a stage 1 Norwood procedure. Pediatr Crit Care Med 2005;6:547–9. 20. Jaquiss RD, Ghanayem NS, Hoffman GM. Early cavopulmonary anastomosis in very young infants after the Norwood procedure: impact on oxygenation, resource utilization, and mortality. J Thorac Cardiovasc Surg 2004;127:982–9. 21. Reddy VM, McElhinney DB, Moore P, Haas GS, Hanley FL. Outcomes after bidirectional cavopulmonary shunt in infants less than 6 months old. J Am Coll Cardiol 1997;29:1365–70. 22. Hughes ML, Shekerdemian LS, Brizard CP, Penny DJ. Improved early ventricular performance with a right ventricle to pulmonary artery conduit in stage 1 palliation for hypoplastic left heart syndrome: evidence from strain Doppler echocardiography. Heart 2004;90:191– 4. 23. Sano S, Ishino K, Kawada M, et al. Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg 2003;126:504 –9.
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PEDIATRIC CARDIAC SURGERY: The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org. To take the CME activity related to this article, you must have either an STS member or an individual nonmember subscription to the journal.
Outcomes After Bidirectional Glenn Operation: Blalock-Taussig Shunt Versus Right Ventricle–to–Pulmonary Artery Conduit Lillian Lai, MHA, MD, Peter C. Laussen, MBBS, Clifford L. Cua, MD, David L. Wessel, MD, John M. Costello, MD, Pedro J. del Nido, MD, John E. Mayer, MD, and Ravi R. Thiagarajan, MBBS, MPH Departments of Cardiology and Cardiac Surgery, Children’s Hospital Boston; and Departments of Pediatrics and Surgery, Harvard Medical School, Boston, Massachusetts
Background. There are distinct physiologic differences between patients with single-ventricle lesions who have undergone the Norwood procedure with a right ventricle– to–pulmonary artery conduit (NW-RVPA) compared with those patients who have undergone the Norwood operation with a Blalock-Taussig shunt (NW-BTS). We evaluated bidirectional Glenn operation outcomes and compared the two groups to assess whether the type of Norwood operation influenced outcomes. Methods. A retrospective chart review compared bidirectional Glenn operation outcomes for children undergoing the Norwood operation with NW-RVPA or NWBTS at Children’s Hospital Boston from January 1, 2002, to December 31, 2003. Results. Of 80 patients undergoing the Norwood operation, 56 (NW-BTS, 27 versus NW-RVPA, 29) returned for
the bidirectional Glenn operation at our institution. The NW-RVPA group had a lower median age at presentation for bidirectional Glenn (4.5 months versus 5.8 months; p ⴝ 0.01), but had better weight gain (20.6 g/day versus 16.5 g/day; p ⴝ 0.03) than the NW-BTS group. No interstage deaths occurred in the NW-RVPA group. There were no differences in morbidity or mortality after the BDG between the two groups. Conclusions. There were no differences in morbidity and mortality outcomes after the bidirectional Glenn operation between the NW-RVPA and NW-BTS groups. Despite younger age at presentation, the NW-RVPA patients had better growth rate, which may have contributed to the similar postoperative outcomes. (Ann Thorac Surg 2007;83:1768 –73) © 2007 by The Society of Thoracic Surgeons
T
The purpose of this study was to compare the interstage outcomes and the outcomes after the BDG in singleventricle patients who had previously undergone the NWRVPA or NW-BTS procedures for stage I palliation.
he Norwood operation, in which a right ventricle–to– pulmonary artery conduit (NW-RVPA) is used to provide pulmonary blood flow in patients with single-ventricle physiology, has been widely adopted after reports of improved hospital and interstage mortality compared with the Norwood operation, where pulmonary blood flow is provided by using a modified Blalock-Taussig shunt (NW-BTS) [1–13]. Factors cited for improved early and interstage survival after the NW-RVPA include higher diastolic pressures, improved coronary and vital organ perfusion, and decreased volume load to the single ventricle owing to a better balance of pulmonary and systemic circulation [1–11]. Despite these distinct differences in hospital and interstage outcomes between these groups, limited information is available about how the type of Norwood operation affects outcomes after the second-stage bidirectional Glenn operation (BDG).
Accepted for publication Nov 22, 2006. Address correspondence to Dr Lai, 401 Smyth Rd, Ottawa, Ontario 2B5, Canada; e-mail: [email protected].
© 2007 by The Society of Thoracic Surgeons Published by Elsevier Inc
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Material and Methods The Committee for Clinical Research at Children’s Hospital Boston, Boston, Massachusetts, approved the retrospective review of patient medical records and also waived the need for patient (parental) consent for the study. Study subjects were selected from a cohort of patients who underwent single-ventricle palliation with the Norwood operation between January 1, 2002, and December 31, 2003 (Fig 1). During this 2-year period, both the NW-RVPA and NWBTS procedures were performed in our institution, and the choice of Norwood operation type was left to the discretion of the surgeon [14]. Technical details of the Norwood operation and early postoperative outcomes in this cohort with hypoplastic left heart syndrome (HLHS) have been previously reported [14]. 0003-4975/07/$32.00 doi:10.1016/j.athoracsur.2006.11.076
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Table 2. Interstage Outcomesa Outcome Duration of interstage period (days) Interstage hospital admission Reason for interstage admission Cyanosis Other reasons Urgent catheterization Urgent surgery Need for gastrostomy tube Weight at BDG (kg) Rate of weight gain (g/day)
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
146 (26–282)
109 (47–244)
0.02
10 (37%)
11 (37%)
0.95
2 8 9 5 6
9 2 8 3 1
0.01
5.6 (3.8–9.3) 16.5 (10–60)
5.5 (3.3–6.6) 20.6 (10–40)
0.50 0.03
1.0 0.7 0.05
a Categoric data are presented as numbers (percentage) and continuous data as median (range).
BDG ⫽ bidirectional Glenn; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-pulmonary artery shunt.
Fig 1. Study population (BT ⫽ Blalock-Taussig; RV-PA, right ventricle-pulmonary artery).
Patients Only patients from this cohort who underwent the BDG operation at our institution were included in the study to prevent bias introduced by the variability in clinical practice between different institutions. Our institutional practice for Table 1. Demographics of the Study Populationa
Male Age at BDG (mo) Weight (kg) Diagnoses HLHS Non-HLHS DORV-MA DILV Congenital AS/Shone syndrome Shunt size and conduit size 3.5 mm 4.0 mm 5.0 mm
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
14 (52%) 5.8 (2.0–10.1) 5.6 (3.8–9.3)
17 (59%) 4.5 (2.2–8.9) 5.5 (3.3–6.6)
0.61 0.01 0.50
24 (87%) 3 (13%) 2 0 1
26 (90%) 3 (10%) 1 1 1
1.0
27 2 27
a
Categoric data are presented as number (percentage) and continuous data as median (range). AS ⫽ aortic stenosis; BDG ⫽ bidirectional Glenn operation; DILV ⫽ double inlet left ventricle; DORV ⫽ double outlet right ventricle; HLHS ⫽ hypoplastic left heart syndrome; MA ⫽ mitral atresia; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-pulmonary artery conduit.
palliation of a patient with single-ventricle lesions after the Norwood operation typically includes the performance of a cardiac catheterization at 4 to 5 months of age to determine candidacy for the BDG, which is performed at approximately 6 months of age. Some patients in our cohort participated in a randomized controlled trial in which the usefulness of magnetic resonance imaging (MRI) was compared with cardiac catheterization for pre-BDG assessment. Thus, some patients received an MRI rather than a cardiac catheterization or both. Data on patient demographics, diagnoses, interstage admissions, preoperative, intraoperative, and postoperative BDG hemodynamic and outcome were collected. We defined the interstage period as the time from hospital discharge after the Norwood operation until the time of the BDG operation. Interstage admission was defined as hospital admission for purposes other than a routine diagnostic cardiac catheterization before the BDG operation or a scheduled BDG procedure. Urgent catheterization was defined as a diagnostic or interventional cardiac catheterization procedure performed on a patient who required interstage admission, and urgent operation was defined as a BDG or other cardiac operative procedure performed in a patient who required interstage hospital admission and needed a cardiac operation before discharge.
Statistical Analysis Continuous data were compared using the Mann Whitney U test, and categoric data were compared using the 2 test. The Fisher exact test was used when the expected value in any category was ⬍5. Postoperative hemodynamic variables and inotrope scores were collected at 6-hour intervals and averaged over 12 intervals for the first 24 hours and compared with baseline values collected on admission to the cardiac
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Results Study Population Of 80 patients undergoing a Norwood operation (NWBTS, 46; NW-RVPA, 34) for stage 1 of single-ventricle palliation during the study period, 56 patients (NW-BTS, 27 [48%]; NW-RVPA, 29 [52%]) returned to our institution for the BDG operation and comprised our study population (Fig 1.) Demographic data of the study population are summarized in Table 1.
Interstage Outcomes and Growth
Fig 2. Age at bidirectional Glenn operation between the Norwood and Blalock-Taussig (NW-BT) group (solid line) and the Norwood and the right ventricle–to–pulmonary artery (NW-RVPA) group (dashed line).
intensive care unit using the repeated measures analysis of variance. The inotrope score was calculated using the formula modified from Wernoversusky and colleagues [14, 15]. Kaplan-Meier survival analysis and the log-rank test were used to compare time to BDG operation after hospital discharge following the Norwood operation and age at BDG between the two surgical groups. Statistical significance was set at a p ⱕ 0.05. Data analysis was performed using SPSS 13.0 statistical software (SPSS Inc, Chicago, IL). Continuous data are reported as median values with ranges, unless specified otherwise.
During the interstage period, no deaths occurred in the NW-RVPA group; however, 6 patients died in the NW-BTS group. No significant difference was found between the two groups with respect to the overall number of interstage hospital admissions, but there was a difference in the reason for admission (Table 2). Cyanosis was the most frequent reason for interstage hospital admission in patients in the NWRVPA group compared with the NW-BTS group (9 versus 2; p ⫽ 0.01), whereas reasons other than cyanosis were more common in the NW-BTS group (8 versus 2; Fischer exact p ⫽ 0.01). These included cardiac failure in 6 patients and intercurrent viral illness in 2 in the NW-BTS group, and 1 patient each in the NW-RVPA group with surgical wound infection and poor feeding. Among patients needing interstage hospital admission (NW-BTS 10, NW-RVPA 11), 6 (22%) of 27 patients in the NW-BTS group and 5 (17%) of 29 in the NW-RVPA group needed management in the cardiac intensive care unit (CICU) during their hospitalization. No significant difference was found in the number of patients needing urgent cardiac catheterizations or urgent surgical intervention between the two groups (Table 2). Of the 9 patients in the NW-BTS group who needed urgent cardiac catheterization, 5 needed an intervention during the catheterization. Catheter-based interventions in this group
Table 3. Hemodynamic Assessment Before Bidirectional Glenn Operation NW-BTS (n ⫽ 27) Echocardiographic assessment Moderate or severe RV dysfunction Moderate or severe TV regurgitation Cardiac catheterization assessmentb Patients undergoing catheterization (n) Cardiac index (L/min/m2) RV end-diastolic pressure (mm Hg) Diastolic blood pressure (mm Hg) Mean pulmonary artery pressure (mm Hg) Systemic oxygen saturation (%) Hematocrit (%) Qp:Qs Pulmonary vascular resistance (U · m2) Patients requiring catheter based intervention Magnetic Resonance Image (n) a
NW-RVPA (n ⫽ 29)
1 (4) 7 (26)
3 (10) 4 (16)
22 (81) 3.0 (1.7–5.8) 10 (4–18) 41 (25–59) 17 (10–28) 77 (67–90) 45 (34–63) 1.2 (0.6–3.0) 1.9 (0.6–5.0) 14 (70) 6 (22)
Categoric data presented as number (percentage) and continuous data as median (range). non-urgent catheterization.
22 (76) 3.1 (1.9–5.5) 9 (4–14) 50 (29–84) 16 (10–23) 75 (62–87) 48 (36–62) 0.95 (.4–1.8) 2.0 (0.8–3.2) 11 (68) 8 (28) b
p Value 0.61 0.25
0.63 0.56 0.004 0.31 0.06 0.20 0.04 0.90 1.0 0.64
Includes data from patients undergoing urgent and
NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-pulmonary artery shunt; Qp:Qs ⫽ ratio of pulmonary to systemic blood flow; RV ⫽ right ventricle; TV ⫽ tricuspid value.
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Table 4. Intraoperative Data After the Bidirectional Glenn Operationa Variable Total pump time (min) Patients needing circulatory arrest (n) Circulatory arrest time (min) Post-CPB lactate level Other procedures with BDG Pulmonary artery enlargement ASD enlargement Tricuspid valve repair
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
65 (47–257) 2 (7)
69 (47–131) 9 (31)
0.50 0.03
12 (1–20)
0.15
1.8 (0.7–7.2) 9 (31)
0.91 0.85
26.5 (17–36) 1.7 (1.2–5.8) 9 (33) 5 (19)
6 (21)
0.84
3 (11) 2 (7)
0 3 (10)
0.11 1.0
a Categoric data presented as number (percentage) and continuous data as median (range).
ASD ⫽ atrial septal defect; BDG ⫽ bidirectional Glenn; CPB ⫽ cardio pulmonary bypass; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-artery conduit.
included dilation of obstruction at the distal aortic arch in 4 patients, and dilation of narrowing in the innominate artery proximal to the insertion of arterial end of the BlalockTaussig shunt in 1. Among the 8 patients in the NW-RVPA group who needed urgent cardiac catheterization, 6 needed interventions. Catheter based interventions included enlargement of atrial communication in 2, dilation and stenting of the right ventricle to pulmonary artery conduit in 1, and a restrictive bulboventricular foramen in another. Two patients in the NW-RVPA group had dilation of obstruction at the distal aortic arch.
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Of the total eight patients requiring urgent surgical intervention after interstage hospital admission (NW-BTS, 5; NW-RVPA, 3), 7 had early BDG operations. One patient from the NW-RVPA group (double inlet left ventricle) had the RVPA conduit placed between the bulboventricular foramen (ie, the attenuated right ventricle) and the main pulmonary artery as a part of the NW-RVPA operation. This patient was readmitted to the hospital for severe cyanosis and had urgent cardiac catheterization that revealed narrowing of the bulboventricular foramen from where the RVPA conduit arose. A 4.0-mm intravascular stent (Express-2, Boston Scientific, Boston, MA) was placed across the narrowed bulboventricular foramen, with improvement of oxygen saturations. Severe cyanosis recurred 2 months after the procedure despite redilation of the intravascular stent. As a result, the patient was converted to a NW-BTS. This patient is included in the NW-RVPA group for analysis. The interstage period was significantly shorter in the NW-RVPA group than in the NW-BTS group, with a median time to BDG of 109 days (range, 47 to 244 days) versus 146 days (range, 26 to 282 days; log-rank p ⫽ 0.02). As a result, patients in the NW-RVPA group were significantly younger compared with the NW-BTS group, with a median age of 4.5 months (range, 2.2 to 8.9 months) versus 5.8 months (range, 2.0 to 10.1 months; log-rank p ⫽ 0.01; Fig 2). Of the 7 patients who required gastrostomy tube placement, 6 (22%) were in the NW-BTS and 1 (3%) was in the NW-RVPA group (Fisher exact p ⫽ 0.05; Table 2). Patients in the NW-RVPA group gained significantly more weight during the interstage period compared with the NW-BTS group (20.6 g/d versus 16.5 g/d; p ⫽ 0.03). As a result, although the NW-RVPA group was younger, there was no difference in body weight compared with the NW-BTS group at the time of the BDG operation (Table 2).
Table 5. Postoperative Hemodynamics During the First 24 Hours Variable Heart rate (beats/min) Mean arterial blood pressure (mm Hg) Left atrial pressure (mm Hg)a SVC (mm Hg)b Sao2 (%) Pao2 (mm Hg) Pao2/Fio2 Inotrope score
a
Group
Baseline
1–12 hr
13–24 hr
p Value
NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA NW-BTS NW-RVPA
142 ⫾ 22 146 ⫾ 23 68 ⫾ 9 62 ⫾ 7 9⫾3 9⫾3 17 ⫾ 3 17 ⫾ 2 87 ⫾ 11 83 ⫾ 9 50 ⫾ 15 47 ⫾ 9 53 ⫾ 8 49 ⫾ 11 6⫾3 5⫾3
132 ⫾ 15 126 ⫾ 18 73 ⫾ 9 70 ⫾ 7 8⫾3 9⫾3 15 ⫾ 4 16 ⫾ 3 78 ⫾ 6 79 ⫾ 5 45 ⫾ 8 42 ⫾ 5 105 ⫾ 32 103 ⫾ 33 8⫾3 6⫾3
118 ⫾ 13 119 ⫾ 18 74 ⫾ 9 74 ⫾ 8 8⫾2 10 ⫾ 4 13 ⫾ 3 17 ⫾ 5 80 ⫾ 6 79 ⫾ 5 43 ⫾ 5 42 ⫾ 4 152 ⫾ 62 149 ⫾ 46 6⫾3 5⫾3
0.17
Left atrial pressure: observations: NW-BTS: n ⫽ 24, NW-RVPA group: n ⫽ 21.
b
0.09 0.56 0.05 0.08 0.51 0.98 0.50
SVC pressure: observations NW-BTS: n ⫽ 11, NWRV-PA: n ⫽ 18.
Fio2 ⫽ fraction of inspired oxygen; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-artery conduit; Pao2 ⫽ partial pressure of oxygen in arterial blood; Sao2 ⫽ peripheral oxygen saturation; SVC ⫽ superior vena cava.
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Table 6. Postoperative Outcomes After Bidirectional Glenn Operationa Variable Delayed sternum closure Inhaled nitric oxide use Nosocomial infectionb Pleural effusion Duration of ventilation (hr) Duration of CICU stay (days) Duration of hospital stay (days)
NW-BTS (n ⫽ 27)
NW-RVPA (n ⫽ 29)
p Value
1 (4) 3 (11) 0 2 (8) 13.5 (6–98)
0 1 (3) 3 (10) 2 (7) 17 (6.5–156)
0.48 0.34 0.23 1.0 0.59
2 (1–10)
2 (1–26)
0.28
6 (3–26)
6 (3–64)
0.77
a Categoric data presented as numbers (percentage), continuous data as b median (range). Nosocomial infection includes blood stream and sternal wound infection.
CICU ⫽ cardiac intensive care unit; NW-BTS ⫽ Norwood operation with modified Blalock-Taussig shunt; NW-RVPA ⫽ Norwood operation with right ventricle-to-artery conduit.
Pre-Bidirectional Glenn Assessment Pre-BDG hemodynamic assessment (Table 3) showed significantly lower diastolic blood pressure and a higher pulmonary–systemic blood flow ratio in the NW-BTS group. Intraoperative variables were similar (Table 4). Postoperative outcomes (Table 5 and 6) showed that the superior vena cava (SVC) pressure decreased over time from baseline for the NW-BTS group compared with the NW-RVPA group, where SVC pressure tended to stay the same compared with the baseline. For the whole cohort, the 12 patients who required BDG when they were younger than 4 months old needed a longer duration of ventilation (22.3 hours [range, 8.5 to 156 hours] versus 14.3 hours [range, 6 to 98 hours], p ⫽ 0.002), had longer stays both in the CICU (3 days [range, 1 to 26 days] versus 2 days [range, 1 to 15 days]; p ⫽ 0.006) and in the hospital (10.5 days [range, 5 to 47 days] versus 5 days [range, 3 to 64 days]; p ⫽ 0.002) compared with those patients who underwent BDG at 4 months old or older. The available follow-up time after discharge after the BDG operation was longer for the NW-BTS group (1.64 years [range, 0 to 3.1 years] versus 0.6 years [range, 0 to 2.3 years]; p ⬍ 0.001). The 12-month survival after BDG was not significantly different for the two operative groups. One patient in the NW-BTS group required cardiac transplantation for persistent cardiac failure and cyanosis, and 2 in the NW-RVPA group died from cardiac failure refractory to medical therapy.
Comment In our cohort of patients undergoing the Norwood operation, patients in the NW-RVPA group underwent the BDG operation at a significantly younger age than the NW-BTS group but had similar outcomes compared with the older NW-BTS group. An important finding in our comparison of the two surgical groups is the better weight gain seen in the NW-RVPA group during the
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interstage period resulting in equal weights at time of presentation for BDG despite a significantly younger age. Although we did not compare daily caloric intake among patients in the two groups, we speculate better somatic growth in the NW-RVPA group based on advantages in their circulatory physiology compared with the NW-BTS group, as detailed in several reports [1, 5, 9, 11, 13]. After the NW-RVPA operation, there is theoretically a better balance of pulmonary and systemic circulation compared with the NW-BTS group because of the absence of diastolic steal into the pulmonary circulation from the BTS. This improves diastolic blood pressure, which in turn allows for better end-organ perfusion, including earlier mesenteric perfusion. With better gut perfusion and less pulmonary overcirculation, one would suspect better weight gain owing to less congestive heart failure and thus fewer feeding difficulties. This may also explain the relatively lower rates of admissions for viral illness and cardiac failure in the NW-RVPA group. Although single-ventricle volume loading may be present after the NW-RVPA procedure owing to regurgitation from the nonvalved right ventricle–to–pulmonary artery conduit, volume load in the NW-BTS procedure may be larger because of the larger fraction of pulmonary blood flow frequently seen in this type of circulation. Cua and colleagues [14] previously reported from this cohort of single-ventricle patients undergoing the Norwood operation that those patients with HLHS who underwent the NW-BTS took longer to establish enteral feeds compared with the NW-RVPA group. In this follow-up study, we found that significantly more NW-BTS patients required gastrostomy tubes to aid with feeding and calorie supplementation during the interstage period. Despite this help, their growth rate was still lower than that in the NW-RVPA group. Their poor growth may be due to increased basal metabolic energy requirements as well as poor nutrient absorption caused by the disadvantages in the NW-BTS circulatory physiology [16 –19]. Previous reports have shown that younger age may be a risk factor for mortality after the BDG operation [20, 21]. In a 2004 report, Jaquiss and colleagues [20] compared the effect of age on outcome for infants with HLHS undergoing the BDG operation. Of the 85 patients they studied, 33 underwent BDG operation when they were younger than 4 months old. Similar to the report by Jaquiss and colleagues, our cohort of patients undergoing BDG operation before they were 4 months old had a comparatively longer duration of mechanical ventilation, CICU stay, and average length of stay compared with those aged older than 4 months. They concluded that patients undergoing BDG operation at younger than 4 months of age consumed more resources than older patients but that it was safe to perform the BDG at this young age. We saw no difference in outcomes overall between the two groups, despite the fact that the RVPA group presented at a significantly younger age compared with the BTS group (4.5 months versus 5.5 months, p ⫽ 0.01). A possible explanation is that the two groups had a similar number of patients who presented before they were 4 months old for the BDG operation (5/27 BTS [19%] versus 7/29 RVPA
[24%], p ⫽ 0.6), or that better health status and weight gain in the interstage period for the younger RVPA group may have resulted in outcomes similar to the older BTS group. A small number of patients in our cohort had intravascular catheters placed in the SVC allowing measurement of pressure in the Glenn pathway. This pressure was significantly higher and remained elevated in the NWRVPA group compared with the NW-BTS group during the first postoperative day, despite having similar pulmonary artery pressures, pulmonary vascular resistance, and right ventricular end-diastolic pressures documented on their preoperative BDG catheterizations. This finding could suggest a restriction to BDG pathway flow, possibly from anatomically smaller pulmonary arteries or higher postoperative pulmonary vascular resistance, or an early manifestation of diastolic dysfunction caused by the ventriculotomy in the NW-RVPA group. A few small studies have suggested better systolic function in the RVPA group [7, 22, 23]; however, the long-term effects of performing a right ventriculotomy to place the RVPA in neonates are unknown. Absence of differences in oxygenation, pleural drainage, and overall outcomes between the two surgical groups suggests that the persistently higher BDG pathway pressure in the NW-RVPA group did not affect clinical outcomes. Our study is limited by its small sample size, retrospective nature, and lack of standardization in management; therefore, our results should be interpreted cautiously. However, patients for the two operative groups were managed during a concurrent time period and thus both groups were subject to similar decision-making processes for proceeding to the BDG operation and postoperative management. The choice of surgical intervention rather than one based on cardiac catheterization for management of early and persistent cyanosis in this cohort of patients, and the type of surgery, such as BDG or conversion to the NW-BTS arrangement in our report, may also be specific to our institution. In conclusion, our study shows that the NW-RVPA group presented at a significantly younger age for their BDG compared with the NW-BTS group, but there was no difference in post-BDG outcomes. We speculate this may be due to better growth rate in the interstage period in the NW-RVPA group compared with the NW-BTS group.
References 1. Azakie A, Martinez D, Sapru A, Fineman J, Teitel D, Karl TR. Impact of right ventricle to pulmonary artery conduit on outcome of the modified Norwood procedure. Ann Thorac Surg 2004;77:1727–33. 2. Bradley SM, Simsic JM, McQuinn TC, Habib DM, Shirali GS, Atz AM. Hemodynamic status after the Norwood procedure: a comparison of right ventricle-to-pulmonary artery connection versus modified Blalock-Taussig shunt. Ann Thorac Surg 2004;78:933– 41. 3. Drinkwater DC Jr, Aharon AS, Quisling SV, et al. Modified Norwood operation for hypoplastic left heart syndrome. Ann Thorac Surg 2001;72:2081– 6. 4. Hraska V, Nosal M, Sykora P, Sojak V, Sagat M, Kunoversusky P. Results of modified Norwood’s operation for hypoplastic left heart syndrome. Eur J Cardiothorac Surg 2000;18:214 –9.
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