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Ann Thorac Surg 2005;80:1582-1591
© 2005 The Society of Thoracic Surgeons
Department of Pediatrics, Division of Cardiology, Department of Surgery, Division of Cardiothoracic Surgery, and Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
Accepted for publication April 25, 2005.
* Address correspondence to Dr Tabbutt, Cardiac Intensive Care Unit, The Cardiac Center, Children's Hospital of Philadelphia, 34th St and Civic Center Blvd, Philadelphia, PA 19119 (Email: tabbutt{at}email.chop.edu).
Presented at the Forty-first Annual Meeting of The Society of Thoracic Surgeons, Tampa, FL, Jan 24–26, 2005. Winner of the J. Maxwell Chamberlain Memorial Award for Congenital Heart Disease.
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsCommentDiscussionReferences |
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METHODS: We retrospectively compared the outcomes of all neonates who underwent a stage I reconstruction between January 1, 2002, and October 1, 2004, with use of the RV-PA conduit and modified Blalock-Taussig shunt (mBTS) interspersed over this time period.
RESULTS: In all, 149 infants underwent a stage I reconstruction (95 mBTS, 54 RV-PA) for hypoplastic left heart syndrome (HLHS) or variants. There was a preference for the RV-PA conduit in patients with aortic atresia (mBTS 30% versus RV-PA 67%, p < 0.01). There was no difference in surgical mortality (mBTS 14% versus RV-PA 17%, p = 0.67), time to extubation (mBTS 4.5 ± 4.8 days versus RV-PA 3.9 ± 3.5 days, p = 0.47), or length of hospital stay (mBTS 25 ± 29 days versus RV-PA 21 ± 23 days, p = 0.52). There was an increased incidence of shunt reinterventions in the patients with the RV-PA conduit (mBTS 17% versus RV-PA 32%, p = 0.04). Patients with RV-PA conduit returned earlier for stage II reconstruction (mBTS 6.5 ± 2.5 months versus RV-PA 5.6 ± 1.7 months, p = 0.05). There was no difference in overall mortality (mBTS 32% versus RV-PA 30%, p = 0.45) with a median duration of follow-up of 18 ± 8 months.
CONCLUSIONS: Comparing shunt strategies (mBTS versus RV-PA) over the same time period, we found no difference in outcome. These data support the need for a larger prospective, randomized trial.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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| This article has been selected for the open discussion forum on the CTSNet Web Site: http://www.ctsnet.org.discuss
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Initial success of the Norwood procedure for hypoplastic left heart syndrome (HLHS) utilized a central shunt, which was soon replaced by a modified Blalock-Taussig shunt (mBTS) as the source of pulmonary blood flow [1]. The modified Norwood procedure, or stage I reconstruction, has subsequently been applied to a variety of cardiac defects characterized by obstruction to systemic blood flow with a functional single ventricle. Survival after the stage I reconstruction with the mBTS has improved over the past 2 decades. Excellent recent surgical survival has been reported as high as 93% [2]. However, there remains a wide range of surgical results dependent in part on the incidence of patient-related risk factors [3], with centers reporting stage I survival at 52% to 86% [3–13]. In 2003, Sano and colleagues [14] reported a significant improvement in stage I morbidity and survival by using a right ventricular to pulmonary artery (RV-PA) conduit rather than mBTS as the source of pulmonary blood flow. Other reports have supported this finding [15, 16]. However, all case series reporting improved outcome with the RV-PA conduit use patients with mBTS as historical controls.
It is well demonstrated that single-institution results improve over time independent of significant changes in surgical approach [2, 7, 8]. These improvements are thought to reflect an increased incidence of prenatal diagnosis, surgical experience, improvement in perioperative care with close attention to low cardiac output syndrome [2, 7, 8], and less tangible human factor [17]. Theoretical advantages of the mBTS include improved pulmonary artery growth owing to the antegrade flow across the shunt throughout the cardiac cycle. The lower diastolic pressures with the mBTS [18–20] are proposed to compromise coronary blood flow and perhaps impact cardiac function. The RV-PA conduit provides antegrade flow to the pulmonary arteries during systole but has diastolic flow reversal, adding to the ventricular volume load and perhaps leading to diminished pulmonary artery growth. The mBTS has a recognized incidence of acute shunt occlusion, which is perhaps less common with the larger RV-PA conduit. The necessary ventricular incision for the RV-PA conduit carries an unknown risk for late arrhythmia and diminished ventricular function in these patients with single-ventricle physiology.
This study provides a comparison of the stage I reconstruction using the mBTS and RV-PA conduit over the same time period. Study objectives include the difference between the two shunt groups with regard to (1) stage I morbidity and mortality, (2) the incidence of shunt revision or intervention, (3) the age at the stage II reconstruction, and (4) interim mortality. In addition we evaluated subgroups of patients with previously reported preoperative risk factors to determine whether shunt type influenced survival.
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Patients and Methods |
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Anatomy and Patient-Related Risk Factors
All patients were born with HLHS or variants with a single ventricle and obstruction to systemic blood flow. Anatomical diagnoses were divided into (1) usual HLHS with mitral stenosis or atresia and aortic stenosis or atresia (n = 102, 69%), (2) malaligned atrioventricular canal defect with a single RV (n = 14, 9.5%), (3) ventricular septal defect or double-outlet right ventricle with mitral stenosis or atresia (n = 17, 11%), (4) single left ventricle (LV) with systemic outflow obstruction, such as double-inlet LV with transposition of the great arteries (n = 14, 9.5%), and (5) other, including truncus arteriosus with a single ventricle (n = 2, 1%). The incidence in our patient population of previously reported preoperative risk factors for increased mortality in patients with HLHS is listed in Table 1. Genetic syndromes in our population included Turners, Ellis-van Creveld, DiGeorge, and Goldenhar syndromes and noncardiac anomalies included scimitar, gastroschisis, duodenal atresia, and tracheoesophageal fistula. Additional cardiac risk factors were considered to be an intact atrial septum requiring emergent intervention, moderate to severe atrioventricular valve insufficiency, and severe ventricular dysfunction. Patients with a preoperative pH less than 7.0, creatinine greater than 2 mg/dL, hepatic enzymes more than 500 U/L, or having received chest compressions were classified as preoperative shock.
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The standard approach, independent of the type of shunt, included an atrial septectomy and division of the main pulmonary artery with side-to-side anastomosis to the diminutive ascending aorta without aortic transaction and homograft patch augmentation of the ascending aorta and arch. Shunt selection was at the discretion of the surgeon. There was an institutional preference toward use of the RV-PA conduit for aortic atresia and the mBTS for single LV. The mBTS was placed usually from the proximal innominate artery to the proximal right PA. The diameter of the polytetrafluoroethylene shunt (Gore-Tex, Gore & Associates, Flagstaff, Arizona) was 3.0, 3.5, or 4.0 mm depending upon patient size, vessel size, and preoperative physiology. The RV-PA conduit evolved over the period of the study. Most commonly, this was a 5.0-mm nonvalved polytetrafluoroethylene shunt placed from the RV infundibulum around the left of the neoaorta to the distal main PA. Modified ultrafiltration was used routinely.
Some patients received a load of milrinone (50 to 100 µg/kg) before separating from bypass, and most patients received an additional 100 to 500 µg/kg between administration of protamine and chest closure. Delayed sternal closure was not routine. Extracorporeal membrane oxygenation or ventricular assist was used rarely when a patient could not be separated from bypass, and more commonly for resuscitation after a cardiac arrest. Routine intensive care unit care in the immediate postoperative period included the use of milrinone, dopamine and narcotic continuous infusions, normal minute ventilation with a low rate (16 to 20 breaths per minute), oxygen to maintain PaO2 at 35 to 40 mm Hg, normothermia, and the discontinuation of muscle relaxants the first postoperative night.
Data Analysis
Data analysis involved five phases. Phase I consisted of evaluation of the distribution of patient demographics (age, weight, prenatal diagnosis), cardiac anatomy, and previously reported risk factors (birth weight less than 2.5 kg, aortic atresia, surgeon, genetic syndrome or noncardiac anomaly, and additional cardiac risk factors) between the two shunt groups. Data are presented as a median (±range) or mean (±SD) for continuous variables and as a count and percent for dichotomous variables. Phase II consisted of univariate analyses of the above risk factors including shunt type for overall mortality using 
2 test and logistic regression within the entire cohort and each shunt type. Data are presented as odds ratio or as a count and percent. Multivariate analysis was then performed using Cox proportional hazards regression analysis for risk factors found to be significant or near significant (p < 0.1) by univariate analysis. Data are presented as hazards ratio and 95% confidence limits (CL). Phase III consisted of Kaplan-Meier survival curves for the entire cohort and with log-rank comparison by shunt type (with and without risk stratification). Data are presented with 95% CL. Phase IV consisted of clinically important time interval (stage I, interstage, and after stage II) comparisons of the incidence of death or transplant between shunt types. In addition, Kaplan-Meier curves using a composite endpoint of death or transplant were stratified by shunt type. Finally, in phase V, an analysis of the above risk factors for mortality was performed in 6 patient cohorts by univariate (2 test and logistical regression) and multivariate (Cox proportional hazards regression) to determine if shunt type was protective. Four cohorts represented two risk factors found to be universally significant in our population (birth weight < 2.5 kg, birth weight 
2.5 kg, presence of additional cardiac risk factors, and absence of additional cardiac risk factors). The final two cohorts were aortic atresia and aortic stenosis. A p value of 0.05 or less was considered significant. All data were analyzed using STATA 8.0 (STATA Corp, College Station, Texas).
Definitions
The initial shunt placed determined the shunt type for the analysis. Patients requiring a shunt revision during the initial surgery that crossed over to the other shunt type were followed up as the initial shunt type. Shunt revisions included those performed during the stage I reconstruction. Surgical mortality was defined as death during the stage I hospitalization or within 30 days of surgery if discharged. For patients transferred back to their referring center (n = 31), the time of transfer was considered time of discharge for both surgical mortality and hospital length of stay.
Follow-Up
Follow-up was obtained for all patients (n = 149) through the duration of the study. The median duration of survivor follow-up was 17 months (range, 4 to 35; n = 107). There was no difference in duration of survivor follow-up between patients with a mBTS (18 months; range, 4 to 35; n = 60) and those with a RV-PA conduit (16.5 months; range, 5 to 34; n = 47; p = 0.31). Stage II reconstruction was performed in 100 patients: 85 patients underwent a bidirectional Glenn or hemi-Fontan procedure, 11 patients had bilateral cavopulmonary anastomoses, 2 patients had a Kawashima procedure, 1 patient with obstruction of the superior vena cava had a fenestrated Fontan, and 1 patient with a diminutive right PA associated with scimitar syndrome and bilateral superior vena cava had upsizing of his RV-PA conduit. Four patients have been transplanted: 3 with RV-PA conduits (2 after their stage II reconstruction) and 1 with a mBTS.
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Results |
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Shunt Interventions and Timing of Stage II Reconstruction
There was no difference in the incidence of transcatheter shunt intervention between the shunt types. There were 13 transcatheter interventions for the entire cohort, with 10 requiring stent placement in the shunt or shunt insertion site. The need for surgical or transcatheter shunt reintervention did not increase overall mortality within the entire cohort (p = 0.19) or within the shunt types, mBTS (p = 0.14) and RV-PA (p = 0.75).
There were more frequent surgical shunt revisions in patients after the RV-PA conduit (13 of 54, 24%) compared with patients with a mBTS (11 of 95, 12%, p = 0.05), with eight revisions being crossover to the mBTS. Outcome of the 8 patients converted from a RV-PA conduit to a mBTS was as follows: 1 surgical death and 1 late death just before the stage II reconstruction; the other 5 patients have undergone their stage II reconstruction. Four patients with a mBTS were converted to a RV-PA conduit, their outcomes were as follows: 2 surgical deaths and 1 late death; the other patient is awaiting the stage II reconstruction. Patients requiring surgical shunt revision had an increased incidence of mortality (50%, p = 0.02). However, the incidence of mortality in patients requiring surgical shunt revision after the mBTS (55%, 6 of 11) did not differ from those after the RV-PA conduit (46%, 6 of 13, p = 0.5). Patients with an RV-PA conduit returned earlier for their stage II reconstruction, however this did not impact the hospital length of stay (Table 5).
Overall Survival
Kaplan-Meier 3-year survival estimate for the entire cohort was 70% (95% CL: 63% to 78%) (Fig 2A). There was no difference in 3-year survival estimates after a mBTS (68%, 95% CL: 59% to 68%) compared with the RV-PA conduit (74%, 95% CL: 63% to 86%, p = 0.45) over the duration of follow-up (Fig 2B).
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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As previously reported in series using historical patients with mBTS as controls, we found no impact of shunt type on the stage I survival when both shunts were utilized over a contemporaneous time period [18, 19]. In addition, we found no difference in important markers of hospital morbidity between the two shunt types. Early survival, with a median duration of follow up in both groups of 17 months, was not different between shunt types. Interestingly, the timing of death or transplant for heart failure differed between the two shunt types. Patients with the mBTS had a significantly higher mortality (18%) during the interstage period. Implementation of a home monitoring program could potentially lower this interstage mortality as recently reported by Ghanayem et al. [21]. Patients with the RV-PA conduit demonstrated a trend towards increased death or transplant after the stage II reconstruction compared with those with the mBTS. Since there are important long-term theoretical concerns regarding the RV-PA conduit it is clearly important to continue to track the outcome of these patients [22].
Patients with the RV-PA conduit required significantly more surgical or transcatheter shunt interventions. This finding may reflect the learning curve associated with optimal shunt placement or more marked conformational changes with the RV-PA conduit related to ventricular loading conditions or patient growth. Surgical shunt revision was associated with increased mortality, independent of shunt type. As previously reported [18], patients showed a trend toward an earlier stage II reconstruction after the RV-PA conduit. Although one group found larger pulmonary arteries by angiography after the RV-PA conduit [20], comparative evaluation of pulmonary artery growth remains critically important.
Patient-related associated preoperative risk factors have been shown to have a significant influence on outcome of infants with HLHS and variants. The impact of these risk factors on mortality are institution dependent and include noncardiac anomalies or genetic syndromes [3, 9, 24], lower birth weight [3, 7, 9, 10, 25], postnatal diagnosis [23], and additional cardiac risk factors including severe preoperative obstruction to pulmonary venous return [3, 26], ventricular dysfunction [3, 27], and moderate to severe atrioventricular valve regurgitation [3, 27]. Earlier reports found aortic atresia to be a risk factor for death [28]. However, more recent reports by the same group and others have not found an impact of aortic atresia on survival [2, 3, 8]. Recent reports have found single LV to be protective [8], but that was not found in an earlier cohort of patients from our institution [3] nor within this study group. Preoperative risk factors for survival found to be significant or showing a trend toward significance were similar in the entire cohort and within each shunt type; these were birth weight less than 2.5 kg, preoperative shock, and additional cardiac risk factors. We did not find that the type of shunt affected survival among patients less than 2.5 kg or among patients with additional cardiac risk factors. Although there was a trend toward improved outcome by univariate analysis in patients with aortic atresia who had a RV-PA conduit compared with those with a mBTS, this trend was not significant by multivariate analysis. This finding may reflect a lack of power of the study or may reflect the study bias of preferentially using RV-PA conduits in patients with aortic atresia. Larger, randomized trials should help determine whether shunt type has an impact on certain patient-related risk factors.
This study is limited by a nonrandomized patient population. There may be an uneven distribution of unrecognized preoperative risk factors between shunt types, and there is an uneven distribution of shunt types over time. This study may not be powered for small differences between comparison groups. Finally, the recent study population limits our evaluation of important late outcomes such as arrhythmia, sudden death, and cardiac dysfunction.
This study provides an important comparison of a large number of patients undergoing the stage I palliation for HLHS or its variants with implementation of the RV-PA conduit and mBTS over the same period at a single institution. The important finding is the similarity between shunt types with regard to stage I morbidity and mortality and intermediate survival. We were unable to identify a particular shunt type that was protective to patients with similar risk factors. Given the potential, unknown, late morbidities possible with the RV-PA conduit, the importance of long-term follow-up cannot be underestimated. This study demonstrates the importance of a prospective randomized trial comparing the mBTS to the RV-PA conduit in patients undergoing the modified Norwood procedure. Appropriate risk stratification is of utmost importance and may challenge statistical analyses. Comparative morbidity outcomes are potentially more important than overall survival.
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Discussion |
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The paper from the Children's Hospital of Philadelphia contrasts the outcome of two techniques for supplying pulmonary blood flow after stage I reconstruction of hypoplastic left heart syndrome, namely the right ventricle (RV) to pulmonary artery (PA) conduit and the Blalock-Taussig (BT) shunt. The RV-PA conduit has important theoretical advantages. Acute elevation of systemic vascular resistance (SVR) that is a consequence of the sympathetic response to stress is a common postoperative occurrence. Acute elevation of SVR has been shown to result in elevation of the pulmonary to systemic flow ratio (Qp/Qs) and can result in a critical decrease in systemic oxygen delivery as more and more of the limited cardiac output from the single ventricle is shunted to the pulmonary circulation. The RV-PA conduit modification is less susceptible to acute elevation of SVR in that acute changes in SVR can only impact Qp/Qs during systole. There is less risk of acute, severe aortopulmonary runoff with the associated critical reduction in systemic cardiac output. This risk to the BT shunt patient appears to be neutralized by sustained afterload reduction, as is used in the Children's Hospital of Philadelphia as well as the Children's Hospital of Wisconsin. Nevertheless, in programs that do not use sustained afterload reduction the relative imperviousness of the RV-PA conduit to changes in SVR may account for the apparent hemodynamic stability and improved survival.
In our own contemporary series, smaller than the Children's Hospital of Philadelphia, we have also seen the peculiar difference in the blood pressure profile, specifically, a higher diastolic pressure in the RV-PA conduit group and a higher systolic pressure in the BT shunt group. Much has been made of the higher diastolic pressure in the RV-PA patients and the potential impact on coronary blood flow. Although the perfusion gradient may be higher in the RV-PA conduit modification, I suspect there is little difference in actual coronary blood flow. If the perfusion gradient were the sole determinant of coronary blood flow, then the preoperative patients with aortic atresia would be at greatest risk as they have the lowest diastolic pressure. Yet these patients are generally quite stable and we are not rushing them off to the operating room for urgent surgery to improve coronary perfusion.
More important may be the higher systolic pressure in the BT shunt patients. The higher systolic blood pressure is the result of the aorta acting as a capacitor, storing a volume of blood at high pressure for later delivery to the pulmonary circulation during diastole. The higher systolic blood pressure is a reflection of the greater pressure volume work of the single right ventricle with a BT shunt. The RV-PA conduit does not have this potential inefficiency, or at least less of it as pulmonary blood flow is delivered at a lower pressure. This increased energy expenditure by the heart in patients with a BT shunt may adversely affect the single right ventricle early and late, impacting function and survival.
If you will excuse my waterworks analogy here, if you have a pumping station, it has to provide both the pulmonary and systemic flow, but in the BT shunt, in fact, we store this quantity of blood at a higher energy level, like pumping it up a water tower, to be used later during diastole, and this is the reason that systolic blood pressure is higher among those who have undergone a BT shunt. The comparison then comes down to whether the early benefits of the improved energy efficiency and lack of susceptibility to acute changes in SVR of the RV-PA conduit outweighs the potential problems early and late that may be the result of the ventriculotomy in a systemic ventricle.
My questions for Dr Tabbutt are as follows: It appears from the experience of the Children's Hospital of Philadelphia that higher risk patients received the RV-PA conduit. In particular, they were more often of the usual hypoplastic left heart anatomy, more often they had aortic atresia, and there were other interesting differences, a borderline increase in noncardiac or genetic syndromes, and also a modest improvement in survival by univariate analysis. Does this represent some sort of selection bias? Were the surgeons consciously, or perhaps unconsciously, matching higher risk patients to the RV-PA conduit?
Do you have any insight into the interstage deaths among the patients who had the BT shunt? Did they have decreased function or tricuspid insufficiency before their demise or did this appear to be a sudden death phenomenon? Interestingly, the risk of the RV-PA conduit patients did not appear to decrease after stage II, in contrast to the patients who underwent the BT shunt, and my question, was this a function of the pulmonary artery size or distortion, were arrhythmias a factor, could this potentially be attributed to the ventriculotomy?
And finally, are you looking at other comparative data, particularly echocardiographic or other postoperative hemodynamic data? In a series such as yours, it may be very hard to use mortality as an end point, and we might need to look at other end points to identify an advantage of one of these procedures over the other.
I congratulate you on an outstanding presentation and a terrific paper, and I agree with you completely that we need to pursue a multicenter randomized trial to look at the outcome in these two variants of this procedure.
Thank you, and I would like to thank the Society for allowing me to discuss this paper.
DR SHUNJI SANO (Okayama, Japan): I congratulate you on your excellent paper and excellent results. I have one comment. The result of BT shunt Norwood, so-called classic Norwood procedure, is based on your center's huge experience. I think you have done more than 1,000 cases of classic Norwood procedure, although the experience of RV-PA shunt is only 40 or 50 cases so far. I think it is not fair to compare these two results in such a situation.
If I will analyze this paper, many surgeons whose experience of RV-PA shunt is 40 to 50 cases can achieve such an excellent result. I believe your results of RV-PA shunt improve with increasing experiences. In Okayama University, we do only 6 to 8 cases in a year, although our result of the recent 5 years is mortality around 6% to 7%, and overall mortality is 10%.
DR TABBUTT: Thank you very much for the questions and comments. With regard to Dr Tweddell's comments, in this study we did not look at the details of the postoperative hemodynamics. It does not surprise me that patient with a RV-PA conduit have improved mixed venous co-oximetry measurements and higher diastolic blood pressure. However, in our patients, that does not translate to markers of improved morbidity or survival. Although the difference your group has found in postoperative hemodynamics between the two shunt types is interesting, if it does not impact comparative morbidity and mortality, then one should be cautious converting to a shunt where the long-term implications of the ventricular incision remain unknown. Although not significant, we found an increase in the incidence of death or transplant after the cavopulmonary anastomosis in patients after the RV-PA conduit. Looking at those specific patients, many had a deterioration in heart function and 3 or 4 had sudden events at home, which may be rhythm related. Long-term outcome of these patients with specific regard to cardiac function and arrhythmia is important.
With regard to the distribution of risk factors between shunt types, this is a retrospective and therefore nonrandomized trial. As I pointed out in the talk, there was an institutional preference for the use of the RV-PA conduit in patients with aortic atresia and the mBTS in patients with a single LV. Other preoperative patient-related risk factors were distributed more evenly between shunt types. Multivariate analyses of the entire cohort and within specific risk factors, including aortic atresia, failed to show a significant improvement in survival between shunt types. Our study may be underpowered to answer the important question of whether a certain shunt types is better for a specific patient cohort.
With regard to echocardiographic and angiographic follow-up, we are currently gathering that data. And finally to touch on Dr Sano's comment that we are still on the learning curve of the RV-PA conduit relative to the mBTS, this is a very good point, which I tried to address in this slide. Both graphs show the study period over time divided into 6-month intervals. The top graph show the incidence of shunt reintervention, which shows a increased incidence earlier in our experience consistent with a learning curve, but as the bottom graph demonstrates, this is not reflected in increased mortality. So although we did have a learning curve, I could not demonstrate that it impacted our survival. Thank you.
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S. Sano Invited commentary Ann. Thorac. Surg., November 1, 2007; 84(5): 1617 - 1618. [Full Text] [PDF]
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J. A. Ballweg, T. E. Dominguez, C. Ravishankar, J. Kreutzer, B. S. Marino, G. L. Bird, P. J. Gruber, G. Wernovsky, J. W. Gaynor, S. C. Nicolson, et al. A contemporary comparison of the effect of shunt type in hypoplastic left heart syndrome on the hemodynamics and outcome at stage 2 reconstruction J. Thorac. Cardiovasc. Surg., August 1, 2007; 134(2): 297 - 303. [Abstract] [Full Text] [PDF]
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 B. Alsoufi, T. Karamlou, B. W. McCrindle, and C. A. Caldarone Management options in neonates and infants with critical left ventricular outflow tract obstruction Eur. J. Cardiothorac. Surg., June 1, 2007; 31(6): 1013 - 1021. [Abstract] [Full Text] [PDF]
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L. Lai, P. C. Laussen, C. L. Cua, D. L. Wessel, J. M. Costello, P. J. del Nido, J. E. Mayer, and R. R. Thiagarajan Outcomes After Bidirectional Glenn Operation: Blalock-Taussig Shunt Versus Right Ventricle-to-Pulmonary Artery Conduit Ann. Thorac. Surg., May 1, 2007; 83(5): 1768 - 1773. [Abstract] [Full Text] [PDF]
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B. Alsoufi, J. Bennetts, S. Verma, and C. A. Caldarone New Developments in the Treatment of Hypoplastic Left Heart Syndrome Pediatrics, January 1, 2007; 119(1): 109 - 117. [Abstract] [Full Text] [PDF]
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N. S. Ghanayem, R. D.B. Jaquiss, J. R. Cava, P. C. Frommelt, K. A. Mussatto, G. M. Hoffman, and J. S. Tweddell Right Ventricle-to-Pulmonary Artery Conduit Versus Blalock-Taussig Shunt: A Hemodynamic Comparison Ann. Thorac. Surg., November 1, 2006; 82(5): 1603 - 1610. [Abstract] [Full Text] [PDF]
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 M. S. Bleiweis and A. Saidi Advances in Neonatal Cardiac Surgery: Historical Perspective and Current Status NeoReviews, September 1, 2006; 7(9): e463 - e473. [Full Text] [PDF]
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T. P. Graham Jr The Year in Congenital Heart Disease J. Am. Coll. Cardiol., June 20, 2006; 47(12): 2545 - 2553. [Full Text] [PDF]
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