Systemic-pulmonary shunts in infants and children

Change in Pulmonary Arteries after Modified Blalock-Taussig Shunt Procedure: Analysis Based on Computed Tomography

Background

Although the modified Blalock-Taussig shunt remains the mainstay method of palliation for augmenting pulmonary blood flow in various congenital heart diseases, the shunt must be carefully designed to achieve the best outcomes. This study investigated the effect of shunt configuration on pulmonary artery growth and growth discrepancy.

Methods

Twenty patients with successful modified Blalock-Taussig shunt takedown were analyzed. Pulmonary artery and shunt characteristics were obtained using computed tomography scans. Differences in the baseline and follow-up diameter ratios and growth in the ipsilateral and contralateral arteries were calculated. The angle between the shunt and pulmonary artery, as well as the distance from the main pulmonary artery bifurcation, were measured. Correlations between pulmonary arteries and shunt configurations were analyzed.

Results

The median interval time between shunt placement and takedown was 154.5 days (interquartile range, 113.25-276.25 days). Follow-up values of the ipsilateral-to-contralateral pulmonary artery diameter ratio showed no significant correlation with the shunt angle (ρ=0.429, p=0.126) or distance (ρ=0.110, p=0.645). The shunt angle and distance from the main pulmonary bifurcation showed no significant correlation (ρ=-0.373, p=0.189). Pulmonary artery growth was negatively correlated with shunt angle (ipsilateral, ρ=-0.565 and p=0.035; contralateral, ρ=-0.578 and p=0.030), but not with distance (ipsilateral, ρ=-0.065 and p=0.786; contralateral, ρ=-0.130 and p=0.586).

Conclusion

Shunt configuration had no significant effect on growth imbalance. The angle and distance of the shunt showed no significant correlation with each other. A more vertical shunt was associated with significant pulmonary artery growth. We suggest a more vertical graft design for improved pulmonary artery growth.

Transcatheter Ductal Stents Versus Surgical Systemic-Pulmonary Artery Shunts in Neonates With Congenital Heart Disease With Ductal-Dependent Pulmonary Blood Flow: Trends and Associated Outcomes From the Pediatric Health Information System Database

Background Surgical systemic-to-pulmonary artery shunts have been the standard approach to establish stable pulmonary blood flow in neonates with congenital heart disease with ductal-dependent pulmonary blood flow. More recently, transcatheter ductal stents have been performed as an alternative, less invasive intervention. We aimed to characterize trends in the utilization of surgical shunts versus ductal stents and compare associated outcomes. Methods and Results Using data from the Pediatric Health Information System, we retrospectively analyzed neonates with congenital heart disease with ductal-dependent pulmonary blood flow who underwent surgical shunt or ductal stent placement between January 2016 and December 2021. Patients were identified by International Classification of Diseases, Tenth Revision (ICD-10) diagnosis and procedure codes. The primary outcome was length of hospital stay. Secondary outcomes were reintervention risk and adjusted hospital costs. Of 936 patients included, 65.2% underwent a surgical shunt over the 6-year period. The proportion who underwent ductal stenting increased from 19% to 53.4% from 2016 to 2021. The median adjusted difference in postintervention length of hospital stay was 11 days greater for the surgical shunt cohort (95% CI, 7.2-14.8; P<0.001). The adjusted reintervention risks within 3 (odds ratio [OR], 3.37 [95% CI, 1.91-5.95], P<0.001) and 6 months (OR, 2.43 [95% CI, 1.62-3.64], P<0.001) were significantly greater in the ductal stent group. Median adjusted index hospital costs were $198 300 ($11 6400-$340 000) versus $120 400 ($81 800-$192 400) for the surgical shunt and ductal stent cohorts, respectively (P<0.001). Conclusions Ductal stenting has become an increasingly utilized palliative approach to secure pulmonary blood flow in neonates with congenital heart disease with ductal-dependent pulmonary blood flow in the United States. Ductal stenting is associated with decreased length of hospital stay and reduced overall cost for the index hospitalization but with a greater reintervention risk than surgical shunting.

Blalock-Taussig Shunt versus Ductal Stent in the Palliation of Duct Dependent Pulmonary Circulation; A Systematic Review and Metanalysis

In infants with ductal dependent pulmonary blood flow, Blalock-Taussig (BT) shunt and Patent Ductus Arteriosus (PDA) stent, are two palliative procedures aimed to restore circulation. A systematic review and metanalysis was performed on studies comparing PDA stents and BT shunts, in accordance with PRISMA guidelines. Meta-analysis revealed the following; (1) a reduced risk of mortality [RR = 0.585 [0.399-0.859], (P = 0.006)], (2) a reduced risk of complications [RR = 0.523 [0.318-0.860], (P = 0.011), and (3) a reduced risk of ECMO use [R = 0.267 [0.101-0.706] (P = 0.008)], all in the stent group. Additionally, stent group showed higher post procedure oxygen saturation [SMD = 1.307 [95% CI 1.065-1.550], (P < 0.001)], and Nakata index [SMD = 0.679 95% CI [0.513 to 0.845], (P < 0.001)]. PDA stenting presents a viable alternative to BT shunt procedure with better post procedure stability.

Effects of protocol-based management on the post-operative outcome after systemic to pulmonary shunt

Objectives

Systemic to pulmonary shunt (commonly known as Modified Blalock-Taussig shunt) is a palliative procedure in cyanotic heart diseases to overcome inadequate blood flow to the lungs. Based on the most recent risk stratification score, the mortality and morbidity of this procedure is still high especially in neonates and over-shunting patients. We developed and implemented protocol-based management in March 2013 to better standardize the management of these patients. The aim of this study is to evaluate the effects of applying this protocol-based management in our center.

Methods

We conducted a retrospective cohort study through chart review analysis.We included all children who underwent MBTS from January 2000 till December 2015. We compared the early postoperative outcome of patients operated after the protocol-based management implementation (March 2013 till December 2015) (protocol group) with patients operated before implementing the MBTS protocoled management (control group).

Results

197 patients underwent MBTS from January 2000 till December 2015. Of the 197 patients, 25 patients were in the protocol group and 172 patients were in the control group. There was a significant improvement in the postoperative course and less morbidity after protocoled management implementation as reflected in ventilation time, reintubation rate, inotropic support duration, intensive care unit ICU stay and significantly lower postoperative complications in the protocol group. Mortality of the control group versus protocol group (19.3% VS 8%) with Standardized Mortality Ratio (SMR) dropped from 2.27 before protocoled management to 0.94 after protocoled management (protocol group).

Conclusion

The study suggests that protocoled management of patients with MBTS can improve the postoperative course and early outcome.

Risk Factors for Failure of Systemic-to-Pulmonary Artery Shunts in Biventricular Circulation

Systemic-to-pulmonary artery shunt placement is an established palliative procedure for congenital heart disease, but it is associated with high morbidity and mortality. Data of all patients with biventricular circulation who underwent systemic-to-pulmonary artery shunt implantation between 2000 and 2016 were reviewed. Endpoints of the study were shunt failure and shunt-related mortality. Shunt failure was defined as any shunt dysfunction requiring intervention or reoperation. Shunt-related mortality was defined as death due to shunt dysfunction. A total of 217 shunts (central shunt, n = 131, Blalock-Taussig shunt, n = 86) were implanted in 178 patients. The median age of the patients was 98 days [1 day to 1.2 years]. Corrective surgery was performed at a median time of 0.6 years [3 months to 7 years] after shunt placement. Shunt failure was diagnosed in 21 patients (9.6%) at a median time of 14.6 days [0 days to 2 years]. Causes of shunt failure were stenosis (n = 11; 5%) and thrombosis (n = 10; 4.6%). The rate of freedom from shunt failure was 89.9 ± 2.6% at 1 year, the rate of shunt-related mortality was 3% (n = 5), and the rate of freedom from shunt-related mortality at 1 year was 97.5 ± 1%. Platelet transfusion was required in 43 patients (20%), all for postoperative thrombocytopenia. Perioperative platelet transfusion (p = 0.03) and shunt size of 3 mm (p = 0.03) were identified as risk factors for shunt failure. Shunt size of 3 mm was also identified as a risk factor for shunt-related mortality. The ideal shunt size in patients with biventricular circulation requiring a systemic-to-pulmonary artery shunt is 3.5 mm or larger. Platelet transfusion increases the risk of shunt failure and should be avoided. Type of shunt and diagnosis have no influence on morbidity or mortality after shunt placement.

Computational fluid dynamics characterization of pulsatile flow in central and Sano shunts connected to the pulmonary arteries: importance of graft angulation on shear stress-induced, platelet-mediated thrombosis

OBJECTIVES

Central (aorta) and Sano (right ventricle)-to-pulmonary artery (PA) shunts, palliative operations for infants with complex heart defects, can develop life-threatening thrombosis. We employed computational fluid dynamics (CFD) to study pulsatile flow in these shunts, with the goal to identify haemodynamic characteristics conducive to thrombus formation.

METHODS

CFD, using the finite volume method with cardiac catheterization data, and computer simulations, based on angiography, were employed to determine flow-velocity field, wall shear stress (WSS) profile and oscillatory shear index (OSI).

RESULTS

At prominent angulation, in central shunts (4 and 3.5 mm), WSS reached 245 and 123 (Pascal-Pa), peak systole and 137 and 46 Pa, end diastole; and, in Sano shunts (5 and 6 mm), WSS attained 203 and 133 Pa, peak systole and 1.6 and 1.5 Pa, end diastole. Counter-rotating flow vortices augmented WSS. These high WSSs can promote platelet aggregation, leading to thrombus formation. The OSIs averaged 0.39, indicative of multidirectional shearing forces. Shunt burden was assessed by averaging WSS, over its luminal area and the cardiac cycle. For the central shunts, these WSSs were 73.0 and 67.2 Pa; whereas, for the Sano shunts, 34.9 and 19.6 Pa. For modified Blalock-Taussig shunts (4 and 3.5 mm), the averaged WSSs were significantly lower at 26.0 and 27.5 Pa, respectively.

CONCLUSIONS

CFD modelling is an important tool to determine blood flow behaviour in shunts. Graft angulation presents a risk for shear stress-induced, platelet- mediated thrombosis, which is more likely to occur in elongated central than in Sano shunts.

The effects of postoperative hematocrit on shunt occlusion for neonates undergoing single ventricle palliation

OBJECTIVES

Our primary objective was to test the effects of first postoperative hematocrit on early shunt occlusion for children undergoing systemic to pulmonary artery shunt placement. Because any intervention to reduce shunt occlusion is only beneficial if it reduces mortality or is, at least, mortality neutral, we also tested the effects of first postoperative hematocrit on in-hospital mortality.

METHODS

We conducted a retrospective study on all neonates who underwent primary systemic to pulmonary artery shunt placement, with or without a Norwood/Damus-Kaye-Stansel procedure, at Columbia University Medical Center between January 2010 and July 2015. Univariable regression was used to test the effects of first postoperative hematocrit on early shunt occlusion and 30-day mortality, clustering standard errors by surgeon. In secondary analyses, we also tested associations between red blood cell transfusion volumes in the first 24 postoperative hours and first postoperative hematocrit, shunt occlusion, and mortality.

RESULTS

Eighty infants met inclusion criteria. Median initial postoperative hematocrit was 41.7% (interquartile range, 37.9-46.0). Six infants (7.5%) died. Four infants (5.0%) died within the first 30 days. Five infants (6.3%) experienced early shunt occlusion. No children with early shunt occlusion died. In univariable models, for every 5 additional percentage points of hematocrit, an infant's odds of early shunt occlusion more than doubled (odds ratio, 2.70; P = .009). The odds of all-cause 30-day mortality remained unchanged.

CONCLUSIONS

Higher postoperative hematocrit levels are associated with early shunt occlusions in infants undergoing primary systemic to pulmonary artery shunt placement. Multicenter investigations are warranted to validate these findings and to determine ideal postoperative hematocrit targets for this population.

Ductus arteriosus stenting: A promising percutaneous palliation in patients with duct-dependent pulmonary circulation

OBJECTIVES

We aimed to study the feasibility and outcomes of ductal stenting in patients with duct-dependent pulmonary blood flow (PBF).

METHODS

Duct-dependent hypoxic patients with confluent pulmonary artery (PA) branches were enrolled for ductal stenting and followed regularly.

RESULTS

Sixty patients, with a median age of 12 (1-1095) days and weight of 2.8 (2.2-8.9) kg, were enrolled. Median right PA (RPA) and left PA (LPA) Z-scores were -1.23 (-10.54 to 2.81) and -0.96 (-8.03 to 3.0), respectively. Mean narrowest ductal diameter was 1.73±0.57 mm and length was 12.78±3.32 mm. Sixty-four stents with mean diameter of 4.21±0.32 mm and length of 14.34±3.44 mm were deployed in 59 patients. The procedure was unsuccessful in one. Post-stenting mean oxygen saturation (SO₂) increased significantly from baseline of 68.88±7.47% to 90.43±6.04% (p<0001). Complications included pulmonary edema in one patient and acute stent occlusion in another. At a median follow-up of eight (2-14) months, mean SO₂ (80.04±7.54%) was significantly higher than baseline (p<0.0001). Median RPA and LPA Z-scores, 0.56 (-2.89 to 3.29) and -0.02 (-2.81 to 3.86), respectively, were significantly higher than baseline. Six patients required re-interventions (shunt in three and angioplasty in three). Six patients died, three due to sepsis and another three with worsened cyanosis due to impaired PBF, probably due to ductal occlusion.

CONCLUSION

Ductal stenting is an effective palliation in patients with duct-dependent PBF. It maintains adequate SO₂ and promotes balanced PA growth at mid-term follow-up.

Modified Blalock-Taussig Shunt in Neonates: Determinants of Immediate Outcome

Forty-six neonates with various conditions of low pulmonary blood flow received a modified Blalock-Taussig shunt with a polytetrafluoroethylene graft. Ages ranged from 2 to 30 days (mean, 14.1 days). Hospital mortality was 10.9%. Shunt block requiring reoperation occurred in 3 patients. Incremental risk factors for early mortality were found to be restrictive atrial septal defect, univentricular physiology, and postoperative reintervention. It was found that a Blalock-Taussig shunt could be performed in the neonatal period with a predictable outcome. Single-ventricle physiology and restrictive atrial septal defect were the major determinants of outcome in this subgroup.

Computational fluid dynamics characterization of blood flow in central aorta to pulmonary artery connections: importance of shunt angulation as a determinant of shear stress-induced thrombosis

The central aortic shunt, consisting of a Gore-Tex (polytetrafluoroethylene) tube (graft) connecting the ascending aorta to the pulmonary artery, is a palliative operation for neonates with cyanotic congenital heart disease. These tubes often have an extended length, and therefore must be angulated to complete the connection to the posterior pulmonary arteries. Thrombosis of the graft is not uncommon and can be life-threatening. We have shown that a viscous fluid (such as blood) traversing a curve or bend in a small-caliber vessel or conduit can give rise to marked increases in wall shear stress, which is the major mechanical factor responsible for vascular thrombosis. Thus, the objective of this study was to use computational fluid dynamics to investigate whether wall shear stress (and shear rate) generated in angulated central aorta-to-pulmonary artery connections, in vivo, can be of magnitude and distribution to initiate platelet activation/aggregation, ultimately leading to thrombus formation. Anatomical features required to construct the computer-simulated blood flow pathways were verified from angiograms of central aortic shunts in patients. For the modeled central aortic shunts, we found wall shear stresses of (80-200 N/m(2)), with shear rates of (16,000-40,000/s), at sites of even modest curvature, to be high enough to cause platelet-mediated shunt thrombosis. The corresponding energy losses for the fluid transitions through the aorta-to-pulmonary connections constituted (70 %) of the incoming flow's mechanical energy. The associated velocity fields within these shunts exhibited vortices, eddies, and flow stagnation/recirculation, which are thrombogenic in nature and conducive to energy dissipation. Angulation-induced, shear stress-mediated shunt thrombosis is insensitive to aspirin therapy alone. Thus, for patients with central aortic shunts of longer length and with angulation, aspirin alone will provide insufficient protection against clotting. These patients are at risk for shunt thrombosis and significant morbidity and mortality, unless their anticoagulation regimen includes additional antiplatelet medications.

Prevention of arteriovenous shunt occlusion using microbubble and ultrasound mediated thromboprophylaxis

Background

Palliative shunts in congenital heart disease patients are vulnerable to thrombotic occlusion. High mechanical index (MI) impulses from a modified diagnostic ultrasound (US) transducer during a systemic microbubble (MB) infusion have been used to dissolve intravascular thrombi without anticoagulation, and we sought to determine whether this technique could be used prophylactically to reduce thrombus burden and prevent occlusion of surgically placed extracardiac shunts.

Methods and Results

Heparin‐bonded ePTFE tubular vascular shunts of 4 mm×2.5 cm (Propaten; W.L Gore) were surgically placed in 18 pigs: a right‐sided side‐to‐side arteriovenous (AV, carotid‐jugular) shunt, and a left‐sided arterio‐arterial (AA, carotid‐carotid) interposition shunt in each animal. After shunt implantation, animals were randomly assigned to one of 3 groups. Transcutaneous, weekly 30‐minute treatments (total of 4 treatments) of either guided high MI US+MB (Group 1; n=6) using a 3% MRX‐801 MB infusion, or US alone (Group 2; n=6) were given separately to each shunt. The third group of 6 pigs received no treatments. The shunts were explanted after 4 weeks and analyzed by histopathology to quantify luminal thrombus area (mm²) for the length of each shunt. No pigs received antiplatelet agents or anticoagulants during the treatment period. The median overall thrombus burden in the 3 groups for AV shunts was 5.10 mm² compared with 4.05 mm² in AA (P=0.199). Group 1 pigs had significantly less thrombus burden in the AV shunts (median 2.5 mm²) compared with Group 2 (median 5.6 mm²) and Group 3 (median 7.5 mm²) pigs (P=0.006). No difference in thrombus burden was seen between groups for AA shunts.

Conclusion

Transcutaneous US with intravenous MB is capable of preventing thrombus accumulation in arteriovenous shunts without the need for antiplatelet agents, and may be a method of preventing progressive occlusion of palliative shunts.

Outcomes of systemic to pulmonary artery shunts in patients weighing less than 3 kg: analysis of shunt type, size, and surgical approach

OBJECTIVE

To evaluate outcomes of systemic to pulmonary artery shunts (SPS) in patients weighing less than 3 kg with regard to shunt type, shunt size, and surgical approach.

METHODS

Patients weighing less than 3 kg who underwent modified Blalock-Taussig or central shunts with polytetrafluoroethylene grafts at our institution from January 1, 2000, to May 31, 2011, were reviewed. Patients who had undergone other major concomitant procedures were excluded from the analysis. Primary outcomes included mortality (discharge mortality and mortality before next planned palliative procedure or definitive repair), cardiac arrest and/or extracorporeal membrane oxygenation (ECMO), and shunt reintervention.

RESULTS

In this cohort of 80 patients, discharge survival was 96% (77/80). Postoperative cardiac arrest or ECMO occurred in 6/80 (7.5%), and shunt reintervention was required in 14/80 (17%). On univariate analysis, shunt reintervention was more common in patients with 3-mm shunts (11/30, 37%) compared with 3.5-mm (2/36, 6%) or 4-mm shunts (1/14, 7%) (P < .003). There were no statistically significant associations between shunt type, shunt size, or surgical approach and cardiac arrest/ECMO or mortality. Multiple logistic regression demonstrated that a shunt size of 3 mm (P = .019) and extracardiac anomaly (P = .047) were associated with shunt reintervention, whereas no variable was associated with cardiac arrest/ECMO or mortality.

CONCLUSIONS

In this high-risk group of neonates weighing less than 3 kg at the time of SPS, survival to discharge and the next planned surgical procedure was high. Outcomes were good with the 3.5- and 4-mm shunts; however, shunt reintervention was common with 3-mm shunts.

Can Randomized Clinical Trials Impact the Surgical Approach for Hypoplastic Left Heart Syndrome?

The Eighth International Conference of the Pediatric Cardiac Intensive Care Society was held in Miami, Florida, December 8 to 11, 2010. The program included a session dedicated to the management of hypoplastic left heart syndrome (HLHS), with particular emphasis on the innovations that have led to contemporary schemes of management and the role of clinical trials in the evolution and acceptance of these strategies. An invited panel of experts reviewed the historical evolution of staged surgical reconstruction, the randomized clinical trials that have been undertaken thus far, and the extent to which these have, or have not, influenced individual and institutional approaches to management of HLHS.

Sternotomy Approach for Modified Blalock-Taussig Shunt: Is it a Safe Option?

Central aorta-pulmonary artery shunts have fallen into disfavor because of shunt thrombosis and congestive heart failure, and a modified Blalock-Taussig shunt via thoracotomy can lead to pulmonary artery hypoplasia and distortion. We reviewed the outcomes of a modified Blalock-Taussig shunt by a sternotomy approach in 20 infants from July 2007 to October 2009. Their mean age was 5.79 months, and median weight was 5.4 kg. A 4-mm graft was placed in 11 patients, a 5-mm graft in 8, and a 3.5-mm graft in 1. There was no incidence of sepsis, seroma, or phrenic nerve palsy. There was one hospital death. The mean hospital stay was 10.4 ± 4.3 days (range, 8–15 days). The mean oxygen saturation at discharge was 89% (range, 81%–93%). The sternotomy approach is technically easier to perform, cosmetically preferable, and probably hemodynamically superior. Correction of branch pulmonary stenosis is easily incorporated into this procedure. The theoretical disadvantage of this method is a potential technical difficulty with sternal reentry for subsequent procedures.

Stent expansion of stretch Gore-Tex grafts in children with congenital heart lesions

OBJECTIVE

To evaluate the efficacy and safety of expanding vascular shunt grafts beyond original nominal diameter using stents.

METHODS

Bench testing confirmed the expandability of 3.5 mm and 4.0 mm vascular Gore-Tex stretch grafts. A retrospective analysis included eleven systemic to pulmonary artery shunts with diminished flow which were stented with the aim of increasing the original nominal diameter of the shunts.

RESULTS

During bench testing, the grafts could be expanded to 4.5 mm and 5.8 mm, respectively. Fourteen stents were implanted in 11 stretch grafts a median of 18.9 months (3.2; 21.6 months) after shunt surgery. There was a median increase in diameter of 1.4 mm (0.9; 1.7 mm) [P = 0.001, 95% CI: 0.47; 1.7) from original nominal to final stented diameter of the shunts with a median gain of 28%. A simultaneous improvement in saturations from a median of 73% (66; 77%) to 87% (84; 89%) [P = 0.015; 95% CI: 3; 22] was observed. No complications were experienced during the procedures.

CONCLUSION

In our limited experience, stretch Gore-Tex vascular grafts can be safely expanded beyond nominal diameters using high pressure vascular stents. This leads to improvement in saturation and pulmonary blood flow. It allows the clinician to tailor pulmonary flow in relation to pulmonary artery size and growth, ensuring best possible timing for the next surgical procedure.

[Stent implantation in palliative central aortopulmonary shunt of congenital cardiopathies with pulmonary hypoperfusion. Experience of 2 cases]

We describe the pioneer experience of balloon angioplasty and stent implantation in the central polytetrafluoroethylene aorto-pulmonary shunt. Two infants 1 and 13 month-old, with cyanotic complex congenital cardiopathy and pulmonary hypoperfusion, presented signs of prosthesis dysfunction with severe and critic hypoxemia. The angioplasty and stent implantation were performed through retrograde femoral arterial approach and "freely" (without a guide catheter) in the first case and venous via by using Judkins right coronary guiding catheter in the second one. Both cases experienced sustained O2 saturation improvement, although the neonate died on the fifth post-procedure day clue to acute renal failure. The postmortem anatomical findings are shown.

Reduced frequency of occlusion of aorto-pulmonary shunts in infants receiving aspirin

OBJECTIVE

Infants with severely reduced pulmonary perfusion due to complex congenital cardiac malformations are in need of an improved flow of blood to the lungs. One option for treatment is to construct a systemic-to-pulmonary arterial shunt. Although such shunts have been used since 1945, their spontaneous occlusion remains a major problem in the long-term.

DESIGN

We studied all infants in whom a systemic-to-pulmonary arterial shunt had been constructed using a Gore-Tex tube graft between December 1989 and March 1996.

PATIENTS

Of 46 infants undergoing construction of a shunt, 7 (15%) died within 30 days of surgery. The shunts had to be taken down in 2 infants. Thus, 37 infants were included in the study. All but three infants received Aspirin. Aspirin was discontinued on the personal decision of individual physicians. Of 22 infants, 3 never received Aspirin, and in 19 it was stopped well before undertaking subsequent surgery. Aspirin was administered continuously to 15 infants until further surgery.

RESULTS

Those in whom Aspirin was discontinued, or not given, and those receiving Aspirin until further surgery, were comparable concerning their age, time of follow-up, severity of the cardiac lesions, and size and type of shunt. Partial or complete occlusion of the shunt occurred in 2 of 15 (13%) infants taking Aspirin, but was seen in 12 of 22 (54%) infants in whom Aspirin was discontinued. Of these, 3 died due to acute occlusion of the shunt.

CONCLUSIONS

Aspirin reduced effectively the rate of occlusion of systemic-to-pulmonary arterial shunts, and should be continued as long as the shunt is in place.

Effects of modified and classic Blalock-Taussig shunts on the pulmonary arterial tree

BACKGROUND

The aim of this study was to assess by angiography the late effects of both classic and modified Blalock-Taussig shunts in terms of growth and development of stenosis and distortion.

METHODS

At a mean of 51 months postoperatively, we retrospectively reviewed the results in 78 patients who underwent creation of Blalock-Taussig shunts (25 classic and 71 modified).

RESULTS

At the level of the anastomosis, the shunt caused a reduction in diameter of the pulmonary artery in 49% of all shunts, major stenosis (>50% narrowing of the lumen) in 14%, and distortion of the pulmonary artery in 19%, findings that did not correlate with the type of shunt. Distortion did correlate with younger age at the time of shunt operation (p=0.01).

CONCLUSIONS

After a Blalock-Taussig shunt, growth of the pulmonary arteries occurred but did not exceed the normal growth of the pulmonary arterial tree. Moreover, a shunt procedure can cause distortion and stenosis of the pulmonary artery, which may have important implications for future corrective surgical intervention. All these findings support earlier complete surgical repair of correctable congenital cardiac defects.

Effect of repair strategy on hospital cost for infants with tetralogy of Fallot

OBJECTIVE

This study compares the total hospital cost (HC) for one-stage versus "two-stage" repair of tetralogy of Fallot (TOF) in infants younger than 1 year of age.

SUMMARY BACKGROUND DATA

Total (one-stage) correction of TOF is now being performed with excellent results in infancy. Alternatively, a two-stage approach, with palliation of infants in the first year of life, followed by complete repair at a later time can be used. In some institutions, the two-stage approach is standard practice for infants younger than 1 year of age or is used selectively in patients with an anomalous coronary artery across the right ventricular outflow tract (RVOT), "small pulmonary arteries," multiple congenital anomalies, critical illnesses (CI), which increase the risk of bypass (e.g., sepsis or DIC), or severe hypercyanotic spells (HS) at the time of presentation. The cost implications of these two approaches are unknown.

METHODS

The authors reviewed 22 patients younger than 1 year of age who underwent repair of TOF at their institution between 1993 and 1995. Eighteen patients had one-stage (1 degree) repair (mean age, 3.4 +/- 3.1 months; range, 3 days-9 months) and 4 patients were treated by a staged approach with initial palliation (1.6 +/- 0.4 month; range, 1.5-2 months) followed by later repair (14.75 +/- 1.5 months; range, 13-16 months). The reasons for palliation were severe HS at time of presentation (two patients), anomalous coronary artery (one patient) and CI (one patient). In the 18 patients undergoing 1 degree repair, 3 (16.6%) presented with HS, 6 (33.3%) had a transanular repair, and 6 (33.3%) were able to be repaired through an entirely transatrial approach (youngest patient, 1.5 months). The HC (1996 dollars) and hospital length of stay (LOS; days) were evaluated for all patients. The HCs were calculated using transition I, which is a cost accounting system used by our medical center since July 1992. Transition I provides complete data on all direct and indirect hospital-based, nonprofessional costs.

RESULTS

There was no mortality in either group. The group undergoing 1 degree repair had an average LOS of 14.5 +/- 11.2 days compared to an average LOS for palliation of 14 +/- 6.4 days. When the palliated group returned for complete repair, the average LOS was 28.8 +/- 25 days, yielding a total LOS for the two-stage strategy of 43 +/- 30.8 days (p = 0.003 compared to 1 degree repair). The HC for 1 degree repair was $32,541 +/- $15,968 compared to $25,737 +/- $1900 for palliation (p = not significant compared to 1 degree repair) and $54,058 +/- $39,395 for subsequent complete repair (p = not significant compared to 1 degree repair) (total two-stage repair HC = $79,795 +/- $40,625; p = 0.001 compared to 1 degree repair). The LOS and HC for the two-stage group combine a total of palliation plus later repair and, as such, reflect two separate hospitalizations and convalescent periods. To eliminate cost outliers, a best-case analysis was performed by eliminating 50% of patients from each group. Using this analysis, the two-stage approach resulted in an average (total) LOS of 16.5 +/- 2.1 days compared to 8.5 +/- 1.4 days for the 1 degree group. Total cost for the two-stage strategy in this best-case group was $44,660 +/- $3645 compared to $22,360 +/- $3331 for 1 degree repair (p = 0.00001).

CONCLUSIONS

The data from this review show that palliation alone generates HC similar to that from 1 degree infant repair of TOF, and total combined HC and LOS for palliation plus eventual repair of TOF (two-stage approach) are significantly higher than from 1 degree repair. Furthermore, these data do not include additional costs for care delivered between palliation and repair (e.g., outpatient visits, cardiac catheterization, serial echocardiography). Although there may be occasions when a strategy using initial palliation followed by later repair may seem prudent, the cost is clearly higher and use of health care resources greater.

Percutaneous transluminal balloon angioplasty of stenotic standard Blalock-Taussig shunts: effect on choice of initial palliation in cyanotic congenital heart disease

To date, attempted balloon dilation of stenotic standard Blalock-Taussig shunts has been largely disappointing. It has been suggested that this may be due to the use of balloons of insufficient diameter. Balloon dilation of stenotic Blalock-Taussig shunts was attempted with use of relatively large balloons in five patients (11 to 67 months old) with cyanotic heart disease who were becoming progressively cyanotic and polycythemic (hemoglobin 17.9 +/- 1.1 g/dl) because of discrete shunt stenosis at the site of pulmonary anastomosis. Balloon diameters selected were equal to or within 1 mm of the unobstructed proximal shunt diameter. Before balloon dilation the diameter at the site of the stenosis was 2.8 +/- 0.8 mm (range 1.7 to 4); after balloon dilation it was 5.7 +/- 1.1 mm (range 4.5 to 7.5). The diameter increased in all patients (range 2.0 to 3.5 mm); the mean increase was 2.8 +/- 0.2 mm (p less than 0.005). Expressed as a percent, the increase in diameter at the stenosis ranged from 80% to 182.4% (mean 108.2 +/- 16.8%). Before balloon dilation the systemic oxygen saturation was 72.8 +/- 9.2% (range 55% to 80%) and after balloon dilation it was 83.6 +/- 2.9% (range 80% to 87%). A satisfactory increase (range 6% to 25%) in blood oxygen saturation was seen in all patients; the mean increase was 10.8 +/- 3.2% (p less than 0.01). At follow-up, the oxygen saturation by pulse oximetry was 85.8 +/- 2.9% (mean 5.8 +/- 1.7 months after balloon dilation) and the hemoglobin was 15.6 +/- 1.9 g/dl (mean 6.6 +/- 1.5 months after balloon dilation).(ABSTRACT TRUNCATED AT 250 WORDS)

Modified Blalock-Taussig shunts: results in infants less than 3 months of age

The optimal procedure for shunting palliation in cyanotic infants remains to be determined. Sixty-two infants less than 3 months of age underwent 63 modified Blalock-Taussig shunts. Their age range at operation was 1 to 84 days (mean, 16 +/- 20 days). Shunts were constructed using 5-mm polytetrafluorethylene tubes in 20 patients and 4-mm polytetrafluoroethylene grafts in 43 patients. There were 13 early deaths (21%; CL, 15% to 27%) of which three deaths (5%; confidence limits, 2% to 9%) were shunt related. The survivors were followed up from 6 to 53 months (mean, 29 +/- 12.5 months). Shunt failure (occlusion, inadequate palliation) occurred in 27 patients. The overall probability rate of adequate shunt function was 58% +/- 8% at 2 years. Univariate and multivariate analyses showed that the size of the graft was a risk factor of shunt failure. Severe distortion of the pulmonary arterial branch was noted in 12 patients. The inferences are: (1) modified Blalock-Taussig shunts provide satisfactory early palliation but late shunt failure is frequent; (2) similar results should be obtained with other shunting procedures; and (3) the optimal procedure should be selected for each cyanotic infant on an individual basis.

The Blalock-Taussig shunt: an analysis of trends and techniques in the fourth decade

The original description of the Blalock-Taussig shunt was published in 1945 and represented the first direct surgical procedure for the treatment of cyanotic congenital heart disease. The present study analyzes the results of Blalock-Taussig shunts performed at Duke University Medical Center during the fourth decade since the original description of the procedure. From 1975 to 1984, 53 classic and 24 modified Blalock-Taussig shunts were performed with a hospital mortality of 8%. These deaths occurred in critically ill patients with either pulmonary atresia or complex congenital cardiac lesions. The results of the early group (1975-1979) were compared to the late group (1980-1984) of patients. There was a greater proportion of infants less than 1 week of age in the late group, and the actuarial event-free shunt survival following operation was significantly better in the late group. This improvement in the late group was apparent both in patients receiving classic and modified Blalock-Taussig shunts and probably represents the effects of advances in microsurgical technique as well as improvement in the support of critically ill infants at the time of surgery by pediatric anesthesiologists and neonatologists. The data in the present study indicate that the mortality associated with Blalock-Taussig shunting is related to the condition of the patient at the time of surgery and the underlying cardiac pathology rather than the age of the patient at the time of shunting. The efforts to further reduce morbidity and mortality associated with Blalock-Taussig shunting should therefore be directed primarily to the support of infants during the preoperative and intraoperative phases of care.

Infection of modified Blalock shunts

A left-sided interposition graft (modified Blalock-Taussig anastomosis) was constructed with polytetrafluoroethylene in a three month old child with tetralogy of Fallot. This shunt thrombosed and a replacement shunt became the site of chronic Pseudomonas infection. The second anastomosis was excised and a third interposition graft was inserted on the right side because the anatomy was unsuitable for a classical Blalock-Taussig shunt. The patient died when he was 12 months old, after signs of infection and shunt occlusion had developed. At necropsy the acutely thrombosed right sided shunt was found to be the site of Candida albicans infection. Gallium and labelled white cell scans, computed tomography, and ultrasound scans had all failed to identify the sites of infection, which were only confirmed at operation or necropsy.

Recent advances in cardiac surgery

Virtually all forms of congenital heart disease can be repaired or significantly palliated. The risk of surgery in infancy continues to decline, and many lesions are being routinely repaired at an early age. This may permit an improved functional result later in life. Other recent advances include the arterial switch procedure for transposition of the great arteries, the palliative repair of hypoplastic left heart syndrome, and the increased application of the Fontan procedure in patients with only one effective ventricle. Combined with an ever-growing understanding of cardiopulmonary physiology, anatomy, and biochemistry, the future of congenital cardiac surgery is bright and exciting.

Technique and experience with azygos patch modified Blalock-Taussig anastomosis for congenital cyanotic heart disease

Seventeen patients 1 day to 28 months old with congenital cyanotic heart disease underwent a modification of the Blalock-Taussig shunt. Eight were newborn infants weighing 2.6 to 4.8 kg. All infants had complex congenital heart defects that were not considered amenable to early correction. There were no early deaths and no shunt failures. Postoperative complications were restricted to prolonged intubation in 2 patients and a subcutaneous wound infection in a 14-day-old infant. Follow-up from 1 to 31 months revealed minimal cyanosis, stable hemoglobin levels, and good shunt murmurs, and there have been no upper extremity complications. There were 2 late deaths; 1 (the oldest patient) was related to medication, and the second resulted from small bowel necrosis. The concept of the azygos vein patch modified Blalock-Taussig shunt involves two factors: (1) mobilizing as much length as possible of the subclavian artery in spite of its distal small size to allow for a tension-free shunt to prevent tension on the anastomosis as growth occurs, and (2) enlarging the subclavian artery distal to the vertebral artery origin with an autologous azygos patch. During performance of a standard Blalock-Taussig shunt, a longitudinal incision is made through the pulmonary artery across the anastomosis into the upper subclavian artery. The appropriate length of harvested azygos vein is used as a patch angioplasty across the shunt. A tension-free shunt with a patulous distal portion is achieved. Pulmonary overcirculation is avoided by the limiting size of the proximal subclavian artery. Temporary occlusion of the shunt at operation resulted in an increased mean blood pressure from 6 to 18% in all infants.(ABSTRACT TRUNCATED AT 250 WORDS)