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Ann Thorac Surg 2007;83:1768-1773
© 2007 The Society of Thoracic Surgeons
a Department of Cardiology, Childrens Hospital Boston, Boston, Massachusetts
b Department of Cardiac Surgery, Childrens Hospital Boston, Boston, Massachusetts
c Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
d Department of Surgery, Harvard Medical School, Boston, Massachusetts
Accepted for publication November 22, 2006.
* Address correspondence to Dr Lai, 401 Smyth Rd, Ottawa, Ontario K1M 2B5, Canada (Email: llai{at}cheo.on.ca).
| 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 non-member subscription to the journal.
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| Abstract |
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Methods: A retrospective chart review compared bidirectional Glenn operation outcomes for children undergoing the Norwood operation with NW-RVPA or NW-BTS at Childrens 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 = 0.01), but had better weight gain (20.6 g/day versus 16.5 g/day; p = 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.
The Norwood operation, in which a right ventricletopulmonary 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) [113]. 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 [111]. 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).
The purpose of this study was to compare the interstage outcomes and the outcomes after the BDG in single-ventricle patients who had previously undergone the NW-RVPA or NW-BTS procedures for stage I palliation.
| Material and Methods |
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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 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
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.
| Results |
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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).
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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 |
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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 ventricletopulmonary 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 [1619].
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 NW-RVPA 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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