The Blalock-Taussig shunt in infants: standard versus modified

Tunable Blood Shunt for Neonates With Complex Congenital Heart Defects

Despite advancements in procedures and patient care, mortality rates for neonatal recipients of the Norwood procedure, a palliation for single ventricle congenital malformations, remain high due to the use of a fixed-diameter blood shunt. In this study, a new geometrically tunable blood shunt was investigated to address limitations of the current treatment paradigm (e.g., Modified Blalock-Taussig Shunt) by allowing for controlled modulation of blood flow through the shunt to accommodate physiological changes due to the patient’s growth. First, mathematical and computational cardiovascular models were established to investigate the hemodynamic requirements of growing neonatal patients with shunts and to inform design criteria for shunt diameter changes. Then, two stages of prototyping were performed to design, build and test responsive hydrogel systems that facilitate tuning of the shunt diameter by adjusting the hydrogel’s degree of crosslinking. We examined two mechanisms to drive crosslinking: infusion of chemical crosslinking agents and near-UV photoinitiation. The growth model showed that 15–18% increases in shunt diameter were required to accommodate growing patients’ increasing blood flow; similarly, the computational models demonstrated that blood flow magnitudes were in agreement with previous reports. These target levels of diameter increases were achieved experimentally with model hydrogel systems. We also verified that the photocrosslinkable hydrogel, composed of methacrylated dextran, was contact-nonhemolytic. These results demonstrate proof-of-concept feasibility and reflect the first steps in the development of this novel blood shunt. A tunable shunt design offers a new methodology to rebalance blood flow in this vulnerable patient population during growth and development.

Choice of shunt type for the Norwood I procedure: does it make a difference?

OBJECTIVES

This study aimed to compare pulmonary artery (PA) growth between patients who received a right ventricle-to-PA (RV-PA) shunt and those who received a modified Blalock-Taussig shunt (mBTS).

METHODS

All consecutive patients with hypoplastic left heart syndrome who underwent the Norwood I procedure between 2001 and 2017 were included in the study. Pre-stage 2 angiograms were analysed to measure the size of the PA. The Nakata index was calculated to estimate PA growth. The ratio of the right PA to left PA cross-sectional area (RPA/LPA) was used to calculate the difference in growth between the 2 branches. Study end points were shunt failure, shunt-related mortality and growth of the PAs.

RESULTS

A total of 223 patients with hypoplastic left heart syndrome (RV-PA group = 137, mBTS group = 86) underwent the Norwood I procedure, and 186 patients (RV-PA n = 116, mBTS n = 70) achieved the stage 2 procedure. PA growth was better in patients with mBTS (Nakata index: RV-PA = 282, mBTS = 315 mm2/m2, P = 0.021). LPA growth was worse compared to RPA growth in both groups (RPA/LPA: RV-PA = 1.21, mBTS = 1.29, P = 1.0). Patients with RV-PA shunts experienced more frequent shunt stenosis compared to patients with mBTS (26 vs 2, P < 0.010). Freedom from shunt failure was 83.3 ± 3.2% and 94 ± 2% at 6 months in the RV-PA and mBTS groups, respectively (P = 0.003).

CONCLUSIONS

PA growth is significantly better in patients who received an mBTS. Moreover, patients with an RV-PA shunt more frequently experienced shunt failure due to shunt stenosis. However, survival after the NW procedure is not shunt dependent and growth of the LPA is less pronounced than RPA, regardless of the shunt type.

Balloon angioplasty and stent implantation performed through systemic-to-pulmonary artery shunts in infants and neonates

Branch pulmonary artery stenosis (BPAS) in the setting of systemic-pulmonary artery shunts (SPS) may result in significant sequelae. Limited information exists regarding the safety and efficacy of pulmonary artery balloon angioplasty and stent implantation via SPS in neonates and infants. This study aimed to examine the feasibility, safety, and efficacy of balloon angioplasty/stent implantation for BPAS performed via SPS in neonates and infants. A single-center retrospective analysis of all patients weighing 10 kg or less who underwent angioplasty for BPAS via SPS was performed. Systemic oxygen saturations and vessel diameter before, during, and after the procedure were compared. Between July 1996 and February 2008, 15 patients underwent 20 catheterizations for the treatment of 27 BPAS via SPS. The patients had a mean weight of 5.6 kg (range, 2.6-10 kg) and a mean age of 7.6 months (range, 7 days to 33 months). The SPS diameter ranged between 2 and 5 mm (median, 3.5 mm). Angioplasty was performed for all 27 lesions, and an additional stent was placed in 5 of these. The average lesion diameter increased from 2.3 ± 1.5 to 4.7 ± 1.7 mm (p < 0.05), and 25 (93 %) of the 27 lesions met the predetermined criteria for success. Systemic oxygen saturation increased from 73 ± 9.5 % to 82 ± 6.8 % immediately after intervention and was 83 ± 7.9 % at discharge (p < 0.05). There were no instances of shunt thrombosis. Two patients experienced transient hypotension during the procedure. No procedural deaths occurred. The study findings suggest that balloon angioplasty or stent implantation performed via SPS appears to be safe and effective treatment for BPAS in neonates and infants.

Impact of shunt type on growth of pulmonary arteries after norwood stage I procedure: current best available evidence

The past decade has seen a substantial improvement in the outcome following surgical palliation for hypoplastic left heart syndrome. This has been attributed to modifications in the surgical as well as postoperative management strategies. One such modification is the reemergence of the right ventricle to pulmonary artery (RV-PA) shunt as an alternative to the modified Blalock-Taussig (mBT) shunt as the source of pulmonary blood flow. The RV-PA shunt has been shown to improve the immediate surgical outcome compared with the classic Norwood procedure with an mBT shunt. Despite the several reported advantages, the impact of the RV-PA shunt on growth of the pulmonary arteries and incidence of late development of central PA stenosis remains unclear. This systematic review evaluates the current best available evidence to address this issue and concludes that the evidence from retrospective studies and only available randomized controlled trial (RCT) is conflicting. The retrospective studies predominantly suggest that the Norwood procedure with RV-PA shunt may have favorable effects on the development of the pulmonary arteries due to even distribution of pulmonary blood flow with greater distal left pulmonary artery growth, resulting in more balanced distal branch pulmonary artery size albeit with a greater degree of central pulmonary artery hypoplasia needing surgical attention. On the contrary, the RCT reports that the overall size of the pulmonary artery on angiography before the stage II procedure was smaller in the RV-PA shunt group than in the mBT shunt group, with no information available on incidence of central pulmonary hypoplasia.

Transcatheter creation of an aortopulmonary shunt in an animal model

BACKGROUND

The surgical creation of an aortopulmonary shunt is an important tool in the therapy of complex congenital heart defects. We report on a transcatheter approach to establish an aortopulmonary shunt in piglets.

MATERIAL, METHODS AND RESULTS

In 10 piglets with a median body weight of 10.5 kg (8-12 kg), a central aortopulmonary shunt was created by radiofrequency perforation from the aorta to the pulmonary trunk, followed by stent implantation. The procedures were performed via the femoral vessels through 5F sheaths under biplane fluoroscopy guidance. A total of six bare metal coronary stents and five polytetrafluoroethylene-covered coronary stents of 3-4 mm diameter were deployed. Four animals were sacrificed immediately after intervention; six pigs were reevaluated 4-5 weeks later for stent patency and measurement of shunt volume. The procedure was successful in all pigs. Median shunt volume was Qp:Qs = 2.4:1. At re-evaluation median body weight had increased to 18 kg (15.5-27.5 kg) P < 0.028. Four of six stents were completely obstructed due to tissue ingrowth in the bare metal stents (two cases) and thrombus formation in the covered stents (two cases). A third bare metal stent had a residual lumen, and a third covered stent was fully open without any thrombus formation or tissue ingrowth.

CONCLUSIONS

Transcatheter creation of an aortopulmonary shunt by radiofrequency perforation and stent implantation is feasible. The use of appropriate covered stents and an effective anticoagulatory regimen seem to be crucial to keep the shunts open.

Development of the pulmonary arteries after the Norwood procedure: comparison between Blalock-Taussig shunt and right ventricular-pulmonary artery conduit

BACKGROUND

The Norwood-Sano procedure for hypoplastic left heart syndrome (HLHS) has been associated with improved postoperative hemodynamics and outcome. This study compared the effect of a Blalock-Taussig shunt with right ventricular-pulmonary artery (RV-PA) conduit before bidirectional Glenn on the development of the PAs.

METHODS

Between January 2000 and June 2007, 42 patients with HLHS underwent bidirectional Glenn: 19 (mean age, 7 +/- 1.5 months) had a Blalock-Taussig shunt (3.5 mm in 15; and 4 mm in 4); 23 patients (mean age, 5 +/- 1 month) had RV-PA conduit (5-mm tube). Patients underwent postoperative cardiac catheterization and echocardiograms.

RESULTS

Total PA (Nakata) index was 192 +/- 10 mm2/m2 in the Blalock-Taussig group and 238 +/- 18 mm2/m2 in the RV-PA conduit group (p = 0.03). In the RV-PA conduit patients, the left and right PAs had comparable diameters. In the Blalock-Taussig group, the left PA was smaller than the right (p = 0.02). The mean PA pressure at the end of the operation was 14 +/- 2 mm Hg in the Blalock-Taussig group and 11 +/-1 mm Hg in the RV-PA conduit group (p = 0.06). Persistent pleural effusion occurred in 4 Blalock-Taussig patients (21%) and in 1 (4%) with RV-PA conduit (p < 0.05). Postoperative arterial oxygen saturation was 80% +/- 2% in the RV-PA conduit group and 74% +/- 2% in the Blalock-Taussig group (p < 0.05).

CONCLUSIONS

The Norwood procedure with RV-PA conduit may have favorable effects on the development of the PA due to even distribution of pulmonary blood flow.

Cardiac emergencies in the first year of life

Cardiac emergencies in the first year of life can be anxiety provoking for the health care provider. An understanding of the pathophysiology involved in the most common emergency department presentations is crucial to the development of appropriate treatment plans. This article discusses the most common causes of cyanotic and acyanotic heart disease in infants.

Does the Site of Insertion of a Systemic-Pulmonary Shunt Influence Growth of the Pulmonary Arteries?

BACKGROUND

The modified Blalock-Taussig shunt is a common palliative procedure for children with cyanotic congenital heart disease. The distal shunt anastomosis can be done to a branch pulmonary artery or to the main pulmonary artery. The purpose of this study was to determine if the site of shunt connection influences pulmonary artery growth.

METHODS

The records of 101 patients with a modified Blalock-Taussig shunt undergoing a subsequent cardiac catheterization between January 2000 and April 2002 were retrospectively reviewed. From the cineangiograms, the diameters of the right and left pulmonary arteries at their first branching and the diameter of the descending aorta at the diaphragm were measured.

RESULTS

If the distal shunt anastomosis was to the right pulmonary artery and there was no antegrade pulmonary flow then the left pulmonary artery was significantly smaller than if the distal connection was to the main pulmonary artery (p = 0.009). Absence of antegrade pulmonary blood flow resulted in significantly smaller right and left pulmonary artery size in general (p < 0.001). No significant differences in pulmonary artery growth were found with respect to gender, anatomic subtype, proximal shunt site, use of cardiopulmonary bypass or size of shunt. By multiple regression analysis absence of antegrade flow and the presence of right-sided shunts were statistically significant predictors of smaller left pulmonary artery and size discrepancy between right and left pulmonary artery.

CONCLUSIONS

These data suggest that in the absence of antegrade pulmonary blood flow, a modified Blalock-Taussig shunt to the main pulmonary artery may promote more uniform branch pulmonary artery growth.

Balloon angioplasty for Blalock-Taussig shunt failure in the early postoperative period

Blalock-Taussig shunt failure is an infrequent but devastating, and often life-threatening, postoperative complication. Percutaneous balloon angioplasty (BA) of a stenotic modified Blalock-Taussig shunt (mBTS) has been successfully used in the setting of progressive shunt failure months to years after shunt creation. Only a few case reports exist where BA was used in the early postoperative period. We report a case series of urgent balloon angioplasty for acute early postoperative mBTS failure. Five patients were performed with BA. BA was performed within the first 24 hr following mBTS placement in three patients. Mean total procedure time was 57 min (range, 34-77 min) and mean total fluoroscopic time was 13.8 min (range, 6.4-24.1 min). Immediate success, defined as increased angiographic diameter, was accomplished in 4/5 procedures. One patient died during the procedure. Two patients survived to Glenn procedure. One patient underwent redo mBTS and one died the day after the BA. In selected patients, BA can relieve acute thrombosis of mBTS. The risk for reintervention and death is high.

Division of modified Blalock-Taussig shunt at correction avoids distortion of the pulmonary artery

BACKGROUND

Modified Blalock-Taussig (BT) shunt causing pulmonary artery distortion has been reported. This distortion may get worse after a corrective operation if the BT shunt is ligated, rather than divided. In this study we examined whether division of modified BT shunt at the time of corrective operation would allow pulmonary artery growth and avoid further distortion.

METHODS

Fifteen patients who had modified BT shunts and subsequently had corrective operations performed by one surgeon between January 1980 to December 1990 were analyzed. The median time from the BT shunt to corrective operation was 46.3 months (range, 3 to 119 months). At the time of corrective procedure, the BT shunt was divided and metal clips were used to occlude and mark each end. At follow-up a chest roentgenogram was obtained and the distance between the two clips was measured.

RESULTS

In all 15 patients measured sequentially the distances between the two clips increased steadily.

CONCLUSIONS

Division of BT shunt at the time of corrective procedure reduces pulmonary artery distortion.

Development of pulmonary arteries after central aortopulmonary shunt in newborns

BACKGROUND

Central shunt (CS) is frequently used to treat diminished pulmonary blood flow in newborns. We analyzed the impact of CS on the growth of the pulmonary arteries (PAs).

METHODS

Twenty-two consecutive newborns underwent a CS procedure. In 15 newborns the preoperative angiograms and angiograms taken before undergoing anatomic or hemodynamic correction procedures were analyzed. The patients were divided retrospectively into two groups by the size of the PA in the preoperative angiogram: group I, patients with PAs more than 4 mm (n = 10), group II, PAs 4 mm or less (n = 5). To compare the development of the PAs in the groups, the Nakata index, McGoon ratio, and lower lobe indices were calculated from angiograms.

RESULTS

The indices were significantly higher in group I before CS, but no differences was found between the groups before anatomic or hemodynamic correction. The postoperative Nakata indices and the McGoon ratios in the groups were higher when compared with preoperative values (group I, p = 0.037 and p = 0.013; group II, p = 0.043 and p = 0.043, respectively). The significant increase of the lower lobe indices only in group II (p = 0.043) suggests faster growth of the PA in this group.

CONCLUSIONS

Optimal diameters of the CS promote growth of the PAs, which was confirmed by the increased Nakata and McGoon indices. The benefit in smaller PAs is greater.

Balloon angioplasty for obstructed modified systemic-pulmonary artery shunts and pulmonary artery stenoses

OBJECTIVES

The results of percutaneous balloon angioplasty for obstructed modified Blalock-Taussig (BT) or central shunts and pulmonary artery (PA) stenoses were studied to assess its role as an alternative to second shunt and surgical PA angioplasty.

BACKGROUND

Obstruction of a modified shunt and PA stenosis related to the shunt or ductus are not infrequent. A second shunt with or without PA angioplastv is required if the PA size, morphology or age of the patient is suboptimal for definitive surgery.

METHODS

From June 1994 to May 1999, balloon angioplasty for obstructed systemic-to-PA shunts was performed in 46 patients, with ages ranging from 1 month to 7.4 years (2.2 +/- 1.9 years). Among the 46 patients, 32 had modified BT shunts, 5 had bilateral shunts, 7 had modified central shunts, and 2 had both modified BT and central shunts. Stenoses were seen in 27 main branch PAs, and interruption was present in three. A concurrent balloon angioplasty was attempted in 28 main branch PAs, but it was performed in only 25 vessels.

RESULTS

Balloon dilation for obstructed modified shunts was considered to be effective in 42 patients (91%), while angioplasty for PA stenosis was effective in 14 vessels and not effective in 11 vessels. After balloon dilation angioplastv, oxygen saturation in the aorta increased from 74.4 +/- 4.3% to 80.8 +/- 3.6% (p < 0.01) in these 46 patients. One patient died of pneumonia. Eight patients required an additional modified BT shunt soon after the procedure because of severe stenosis or interruption at main branch PA. After a mean follow-up period of 11.6 +/- 5.4 months, 29 patients underwent a repeated imaging study to evaluate the morphology and size of the PAs. Of these 29 patients, 26 underwent open-heart surgery, with two mortalities.

CONCLUSIONS

When a second shunt is under consideration because of obstruction of the modified shunt, balloon angioplasty is a possible alternative procedure. Pulmonary artery stenosis, if present, can be simultaneously dilated.

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.

The modified Blalock-Taussig shunt: clinical impact and morbidity in Fallot's tetralogy in the current era

BACKGROUND

The Blalock-Taussig shunt is considered a low-risk management option for palliation in tetralogy of Fallot, but the morbidity associated with a Blalock-Taussig shunt can have a significant impact on patient care. We reviewed the outcome for this operation in the current era.

METHODS

Between 1990 and 1994, 65 children with tetralogy of Fallot received a modified Blalock-Taussig shunt. Sixty patients who had follow-up angiography were assessed for clinical outcomes and shunt-related morbidity and mortality. From the same study period, 68 of 247 pediatric patients who underwent angiography and tetralogy repair, but did not receive palliation, were randomly selected to comprise a comparison group.

RESULTS

Palliation was more likely in the presence of a complicated tetralogy malformation or if there was an associated medical condition. Median age at palliation was 58 days (range: 1 to 535 days). Ninety-five percent of shunts were right-sided. Self-limited morbidity complicated 11% of shunt operations. Significantly smaller distal right pulmonary arteries were observed in the palliated group before total repair compared with findings in the group without palliation and 33% of patients who underwent palliation had angiographic evidence of pulmonary artery distortion. Shunt stenosis was common and correlated with younger age at palliation. Shunt occlusion resulted in one death. Excluding noncardiac causes of death, overall survival was 90% in the palliated group versus 97% in the nonpalliated group (p = 0.09).

CONCLUSIONS

Pulmonary artery hypoplasia and angiographic evidence of pulmonary artery distortion are common after initial palliation by a modified Blalock-Taussig shunt. Neonatal palliation was associated with significantly smaller pulmonary arteries before repair, which necessitated additional interventions.

Tetralogy of Fallot with diminutive pulmonary arteries: preoperative pulmonary valve dilation and transcatheter rehabilitation of pulmonary arteries

OBJECTIVES

This study sought to determine the results of a novel transcatheter management approach in tetralogy of Fallot with diminutive pulmonary arteries.

BACKGROUND

Tetralogy of Fallot with diminutive pulmonary arteries and severe pulmonary stenosis is rare and resembles tetralogy of Fallot with pulmonary atresia: There is a high incidence of aortopulmonary collateral channels, arborization abnormalities, stenoses and need for multiple operations. Because a combined catheter-surgery approach facilitates repair in these patients, such an approach may benefit those with diminutive pulmonary arteries and pulmonary stenosis.

METHODS

Clinical, catheterization and surgical data were studied retrospectively for 10 such patients undergoing preoperative pulmonary valve balloon dilation, among other transcatheter interventions, from January 1989 to January 1995.

RESULTS

Initially, the Nakata index ranged from 20 to 98 mm2/m2 (mean 67 +/- 28 mm2/m2). The pulmonary valve was first balloon dilated (mean balloon/annulus 1.5 +/- 0.3), and the mean initial valve annulus Z score (-4.0 +/- 1) increased to -33 +/- 1.1 (p < 0.01) Other interventions included branch pulmonary artery balloon dilation (7 patients, 23 vessels) and coil embolization of aortopulmonary collateral channels (8 patients, 31 collateral channels). At preoperative follow-up catheterization, the mean pulmonary annulus Z score was -3.1 +/- 0.7, and the Nakata index increased to 143 +/- 84 mm2/m2 (p < 0.03). All patients underwent complete surgical repair successfully. At a mean follow-up period of 2.6 +/- 2 years, right ventricular pressure was < 70% systemic in all patients and < 50% systemic in seven.

CONCLUSIONS

In patients with tetralogy of Fallot, severe pulmonary stenosis and diminutive pulmonary arteries, initial pulmonary valve balloon dilation increases the annulus Z score and anterograde pulmonary blood flow and facilities simultaneous coiling of aortopulmonary collateral channels and access for branch pulmonary artery dilation, all of which results in pulmonary artery growth, simplifying surgical management.

Modified Blalock-Taussig shunt using allograft saphenous vein: six years' experience

BACKGROUND

The occurrence of life-threatening late infectious complications after the use of expanded polytetrafluoroethylene conduits as modified Blalock-Taussig shunts prompted us to apply allograft saphenous veins instead.

METHODS

In 23 cyanotic patients (age, 1 week to 18 years) allograft saphenous veins were used for performing Blalock-Taussig shunts from July 1989 onward. Veins stored in Hank's solution were implanted in 8 patients and cryopreserved ones in 15. All patients were followed up regularly up to 15 months.

RESULTS

There were two early and two late deaths: none were related to shunt occlusion. Clinical, angiographic, and echocardiographic studies proved that, except for one early occlusion, all shunts were patent and functioning well after an average of 41 months. Donor cells disappeared 1 to 3 days after implantation, and several months after the operation both the wall and the luminal surface of the grafts were repopulated with cells possibly of recipient origin. No difference was found between veins stored in Hank's solution only and cryo-preserved grafts, concerning clinical outcome and histology.

CONCLUSIONS

Allograft saphenous veins function well as modified Blalock-Taussig shunts at least up to 6 years. Owing to the good results and lack of complications their clinical use is recommended.

Ascending aorta to right pulmonary artery interposition shunt in critically ill infants

In spite of a trend toward earlier complete repair, some neonates and infants with complex cyanotic heart disease continue to require interim palliation with systemic-to-pulmonary artery shunts. A variety of shunt procedures have been proposed, each with inherent advantages and disadvantages. We have found a prosthetic interposition shunt between the ascending aorta and right pulmonary artery (AA-RPA) to be effective in very young infants with small vessels. Over a 15-year period, 51 patients, mean weight 3.33 kg and mean age 59 days, underwent this procedure with a 13% perioperative mortality and a 78% 2-year overall shunt patency rate. We conclude that the AA-RPA interposition shunt is a safe, effective procedure in these infants.

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)

Progress of patients with pulmonary atresia after systemic to pulmonary arterial shunts

Between February 1980 and June 1987, 42 shunts were placed in 39 infants with pulmonary atresia: 33 were modified Blalock-Taussig shunts with polytetrafluoroethylene (PTFE) and 9 were classic Blalock-Taussig shunts. There were four hospital deaths not related to the shunts. The remaining 35 patients were followed up for 1.6 months to 6.3 years (mean, 24.7 +/- 18 months). Repeat cineangiocardiographic studies revealed stenosis or distortion of the pulmonary arteries related to the site of the shunt in 11/22 patients (50%) with PTFE shunts and in 1/6 (17%) with classic Blalock-Taussig shunts; the stenosis was severe in only 1 patient. Mean increase in the pulmonary arterial index in the group with classic Blalock-Taussig shunts was 117 +/- 52 mm2/m2 (not significant) and in the group with PTFE shunts, 158 +/- 21 mm2/m2 (p less than 0.001). Late shunt occlusion occurred in 1 patient 23 months postoperatively. Thereafter, shunt patency rate remained at 94% +/- 6%. At the end of 1 year 81% +/- 7% of patients were judged to have adequate palliation, but between 2 and 3 years, only 60% +/- 10%. Univariate analysis showed that after 2 years the ranking order for successful palliation was classic Blalock-Taussig, 5-mm PTFE, and 4-mm PTFE shunts, but differences did not achieve statistical significance.

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.