Early Shunt Failure Research Articles

Bovine Mesenteric Venous Graft as an Alternative Conduit in Patients with Cyanotic Heart Disease with E-Polytetrafluoroethylene Graft Failure Caused by Thrombophilic Factor Positivity after Modified Blalock-Taussig Shunt

Modified Blalock-Taussig shunt (MBTS) is a palliative operation for cyanotic congenital heart disease (CCHD) in patients for whom total correction is not appropriate. Many synthetic or biologic grafts have been proposed as alternative shunt materials. The use of a bovine mesenteric venous graft (BMVG) as a systemic-to-pulmonary artery shunt conduit without the administration of antiaggregant and anticoagulant has been proposed as a treatment for neonates with CCHD, but few reports address the importance of thrombophilic risk factors in MBTS and bovine venous graft as a shunt material. We used BMVG as a shunt material without any antiaggregant or antiplatelet regimen in 13 patients with CCHD, all of whom were candidates for MBTS and had thrombophilic risk factors assessed in our initial study. Early shunt failure occurred in the first 3 patients and was attributed to less surgical experience with this graft. No complications were attributable to graft material or surgery itself. In all cases functioning MBTSs were observed on follow-up. Our study results show that thrombophilic factors should be evaluated before the MBTS procedure. BMVG could be the choice of graft for use without the administration of antiaggregant and anticoagulants in patients with thrombophilic risk factors.

Observations regarding failure of cerebrospinal fluid shunts early after implantation

Despite advances in cerebrospinal fluid (CSF) diversionary techniques, shunt failure due to infection or malfunction remains a persistent problem in hydrocephalus care. The aim of this study was to evaluate the independent predictors of early shunt survival after implantation in a large cohort of patients. The authors retrospectively reviewed the records of all patients who had undergone shunt implantation procedures at their institution during an 8-year period. They analyzed the independent predictors of shunt survival in 116 failed shunt placement procedures (infection or malfunction) by performing univariate and multivariate factorial analyses. Analysis of the 116 failed shunts in the 396 new shunt placement procedures performed revealed that age was a significant independent predictor of shunt survival time in failures due to malfunction (p < 0.05) as well as infection (p < 0.05). In addition, a significant relationship between patient race and shunt survival was also found. As suggested by data in other studies focused on this outcome, early shunt failure occurs sooner in younger patients. Interestingly, this study is one of few whose data have revealed that race may affect shunt failure after implantation. Specifically, shunt failure due to infection resulted in significantly shorter shunt survival time in non-white patients compared with that in white patients. Among the shunts that failed due to malfunction, however, white patients had shorter shunt survival times.

Complications of scoliosis surgery in children with myelomeningocele.

The purpose of the present study was to evaluate whether the high incidence of complications in scoliosis surgery in myelomeningocele (MMC) could be attributed to the surgical technique and whether improvements were possible. Between 1984 and 1996, 77 patients with MMC and scoliosis were treated surgically. The clinical and radiological follow-up ranged from 1 to 10 years with a mean follow-up of 3.6 years. The mean age at time of surgery was 12 years 8 months. The average preoperative scoliosis measured 90.20 degrees and was corrected by 47%. The first four patients were stabilized with Harrington rods after anterior correction with a Zielke device (group 1). Twenty-five patients were operated only from posterior, using Cotrel-Dubousset (CD) instrumentation (group 2). In 13 patients an anterior release and discectomy was performed prior to CD posterior instrumentation (group 3). In 26 patients (group 4) this was combined with an anterior instrumentation. The 9 patients of group 5 had congenital vertebral malformations which made a special treatment necessary. Complications could be divided into hardware problems, such as implant failure, dislocation or pseudarthrosis, infections, anesthetic, and neurologic complications. Hardware problems were seen in 29% of all patients. More hardware problems were seen with the Harrington rod (75%) and after solitary posterior instrumentation (30%). The occurrence of pseudarthrosis was dependent on the surgical technique, the extent of posterior spondylodesis, and lumbosacral fusion. Patients with hardware problems had a mean loss of correction of 49% compared to 13% in the other patients. Depending on the different surgical techniques a loss of more than 30% was seen in 12-75% of the cases. Early postoperative shunt failure occurred in four cases; delayed failure - after more than 1 year - in three cases. One patient died within 1 day due to an acute hydrocephalus, another died after 2 1/2 years because of chronic shunt insufficiency with herniation. Wound problems were not dependent on the surgical technique, but on the extent of posterior spondylodesis and the lumbosacral fusion. Based on this analysis we believe our current practice of instrumented anterior and posterior fusion is justified. Further, we are very careful to check shunt function prior to acute correction of spinal deformity.

Intracranial Arachnoid Cysts: Treatment Alternatives and Outcome in A Series of 25 Patients

A series of 25 patients with intracranial arachnoid cysts is analyzed retrospectively. There were 14 males and 11 females ranging in age between a few days and 58 (mean 10) years. Seventy-six percent of patients were children below the age of 15 years. Most of the patients presented with symptoms and signs of long-standing raised intracranial pressure, while localizing signs were rather uncommon. The clinical manifestations were often mild relative to the large size of the cyst. Associated hydrocephalus was present in three patients: one with suprasellar cyst and two with posterior fossa cysts. Seven patients with mild symptoms and small cysts were treated conservatively, while the remaining 18 patients underwent surgical treatment. The initial surgical procedure consisted of craniotomy and fenestration of the cyst in three patients, and cystoperitoneal shunting in the other 15. Of the three patients who underwent craniotomy, one improved postoperatively, while the remaining two developed complications consisting of wound infection and postoperative epilepsy in one and permanent severe neurological deficit in the other. In contrast, six of the 15 cysts treated by shunting resolved completely, eight were smaller, and one remained unchanged. Radiological regression of the cyst after shunting was associated with various degrees of clinical improvement in 13 patients (87%). Two (13%) of 15 shunted patients developed complications in the early postoperative period, consisting of wound infection in one and early shunt failure in the other. Three patients (20%) with shunts had late complications during the follow-up period, consisting of recurrent shunt failure in the first, subdural hematoma in the second, and perforation of the peritoneal catheter into the hepatic bile ducts in the third. These findings, as well as recent data from the literature, suggest that in the management of intracranial arachnoid cysts, cystoperitoneal shunting was more effective and had fewer serious complications than craniotomy and cyst fenestration, and therefore, it is recommended as the treatment of first choice.

Rationale and methodology of the multicenter pediatric cerebrospinal fluid shunt design trial. Pediatric Hydrocephalus Treatment Evaluation Group.

Cerebrospinal fluid shunt failure remains a common and at times overwhelming problem in pediatric patients with hydrocephalus. Two new shunt valve designs, the Orbis-Sigma (Cordis Corporation, Miami, Florida) and the Delta valve (PS Medical, Goletta, California), have flow/pressure characteristics dramatically different from those of standard differential pressure valves which have been used for over three decades. Both new designs reduce the siphoning effect in the upright position, and have been reported to reduce shunt failure rates in uncontrolled series, allegedly due to reduction in shunt overdrainage. Most mechanical shunt failure in the first 2 years after implantation is due to proximal shunt obstruction, overdrainage, and loculated ventricles. By reducing the incidence of slit ventricles associated with standard valves, both new designs could be envisioned as reducing the early mechanical complications. The improved results with both new valves could, however, also be to a large extent due to other confounding effects of shunt surgery, including patient selection, surgical technique, and specific configuration of the components of the shunt other than the valve. There are also theoretical reasons why these valve designs might be worse than their predecessors, including the narrow orifice and high resistance of the Orbis-Sigma, and the flexible membrane of the siphon control portion of the Delta valve, which may increase the ventricular pressure in the upright position or become blocked by encasing scar tissue. For this reason a randomized trial is required to determine efficacy, and a standard differential pressure valve is required as the control design. A significant reduction in early shunt failure would dramatically improve the morbidity and mortality of pediatric hydrocephalic patients, as well as providing substantial savings to the health care system. Failure to determine any difference would focus attention on other issues surrounding shunt surgery, such as patient characteristics or surgical technique.

Percutaneous Creation of Arteriovenous Hemodialysis Grafts: Work in Progress

To develop a technique of percutaneous creation and/or revision of arteriovenous hemodialysis access grafts, and to study the feasibility of the technique in the acute setting. Arteriovenous shunts, consisting of silicone-covered Wallstents 6 (n = 10) or 8 (n = 1) mm in diameter and 11-17 cm in length, were created in 10 mongrel dogs. All shunts were created percutaneously except one, in which the carotid artery was exposed surgically and the jugular vein accessed percutaneously to create a straight external graft. All other grafts were femoral loops (femoral artery to femoral vein). Eight were tunneled subcutaneously and three were left external. All shunts were delivered through 10-F peel-away sheaths. The 11 shunts were allowed to flow for a mean of 4 hours (range, 1.0-6.5 hours) before the animals were killed. Leakage around the "anastomoses" was not observed. Leaks in the silicone covering were observed, resulting in one early shunt failure. Two attempted survival experiments were aborted due to early shunt dislodgment at 1.5 and 3.5 hours. Percutaneous arteriovenous shunt creation is feasible through acceptably small sheaths. Peel-away sheath placement of the stent circumvents the technical problem of placing a closed device into both artery and vein. This technique may allow percutaneous revision of existing hemodialysis access grafts and possibly de novo creation of grafts in humans, but modification of the grafts will be needed to prevent dislodgment.

The Blalock-Taussig Shunt in Infants: Standard versus Modified

In recent years, the modified Blalock-Taussig shunt—a polytetrafluoroethylene graft from the subclavian artery to the pulmonary artery—has been preferred over the standard shunt by some surgeons because (1) it requires less dissection and (2) length of native vessels is not critical. From January, 1979, to June, 1985, we operated on 51 infants less than 1 year of age, including 26 less than 1 week of age, to palliate severe complex cyanotic congenital cardiac malformations. Twenty-four modified Blalock-Taussig shunts and 29 standard Blalock-Taussig shunts were created. The groups were concurrent. We reviewed all available cineangiograms and measured branch pulmonary and subclavian arteries. Pulmonary artery index was not different preoperatively in patients given a modified versus a standard Blalock-Taussig shunt (144 ± 118 and 118 ± 59 mm 2/m 2, respectively), but it was greater postoperatively in patients with a modified shunt (431 ± 188 and 189 ± 106 mm 2/m 2) ( p = 0.07). Distortion of the pulmonary artery occurred less often after a modified Blalock-Taussig shunt (4/11) than a standard Blalock-Taussig shunt (6/8) ( p = 0.06), though none of the distortions was severe. Early and late shunt failure occurred less often with a modified shunt (5/24) than with a standard shunt (15/29) (p < 0.05). The modified Blalock-Taussig shunt had advantages over the standard Blalock-Taussig shunt in our series: pulmonary artery growth was greater, distortion of pulmonary arteries was less commonly seen, and shunt failure occurred less often. Thus, in infants, we believe the modified Blalock-Taussig shunt should be considered a reasonable alternative to the standard Blalock-Taussig shunt.

Ventricular gallbladder shunts: An alternative procedure in hydrocephalus

Hydrocephalus is a frequently encountered problem in infancy and is most commonly treated by placement of ventriculoperionteal (VP) or ventriculoatrial (VA) shunts. Other sites for insertion of the distal shunt have included the stomach, ureter, and fallopian tube. This report describes an experience with ventricular gallbladder shunts (VGB) in 25 children performed from 1970 to 1985. There were 13 girls and 12 boys ranging in age from 6 months to 16 years. Diagnosis included meningomyelocoele (7), congenital hydrocephalus (7), postmeningitic complications (5), intracranial tumor (4), and intraventricular hemorrhage (2). Indications for operation included VP shunt infection (15), massive ascites following VP shunt (3), VA shunt infection (4), and distal shunt malfunction due to fibrinous adhesions or cysts (secondary to infection; (3). Three patients had early shunt failure due to proximal obstruction (2) and gallbladder atony (1). Shunt revision was required in two and the atony was successfully treated with cholecystokinin in one. Fourteen shunts remain in place, two patients have been lost to follow-up, and three children died from unrelated causes. Seventy percent of the 20 patients available for long-term follow-up have functional shunts in place. The VGB shunt procedure remains an attractive alternative for patients with hydrocephalus in whom intraperitoneal and intravascular shunts are no longer feasible.

Modified blalock-taussig shunt operation without cardiac catheterization: Two-dimensional echocardiographic preoperative assessment in cyanotic infants

Between May 1981 and December 1983, 25 infants with cyanotic congenital heart defects underwent 26 Blalock-Taussig shunt operations without cardiac catheterization and angiocardiography. In these infants, the diagnosis was established by 2-dimensional echocardiography (2-D echo) supplemented with clinical findings, chest x-ray and electrocardiography. The right and left pulmonary artery measurements, a prerequisite for a shunt operation, determined by 2-D echo were compared with those at surgery and had an excellent correlation (r = 0.94). No infant died as a consequence of an early shunt failure, and only 1 died of postoperative pyothorax. In conclusion, 2-D echo may eliminate the need for invasive investigation in selected patients undergoing the Blalock-Taussig anastomosis.

Peritoneovenous shunt occlusion. Etiology, diagnosis, therapy.

Electronic pressure testing of every LeVeen valve has practically eliminated mechanical malfunction as a cause of shunt failure. Nonetheless, failures do occur and in a series of 240 cases, early or late shunt failure occurred in 29 patients. Thirty-five additional cases of failures were either referred by other physicians over a period of 6 years or information and x-rays were accumulated by direct contact. Shunt failure becomes manifest by a sudden reaccumulation of ascites in patients with a previously functioning shunt. In immediate failure, the ascites may fail to disappear after surgery or reaccumulate if removed. Ideally, caval clotting should be first excluded by x-ray visualization of the superior vena prior to injection of the shunt with contrast agent. Shuntograms are done with fine-bore needles. The venous pressure is also measured. The entry of contrast into the vena cava without pooling indicates a patent venous limb. The contrast will empty from the venous tubing with forceful inspiration if the entire system is patent. The venous tube will not clear if the valve or peritoneal collecting tubes are blocked. Only the valve and collecting tube need then be replaced if contrast enters the cava but does not leave the venous tubing. Occluded valves must not be flushed to restore patency since inflammatory exudate and cellular debris are erroneously identified as "fibrin flecks." Histology and culture are mandatory. Immediate and early failure are often caused by malposition of the venous tubing. Malplacements can often be diagnosed simply by chest x-rays. Intraoperative injection of methylene blue into the venous tubing establishes a satisfactory washout prior to wound closure. Fresh clots in the vena cava can be dissolved by the slow injection of streptokinase into the venous tubing. Other patent veins are chosen for access. Patients having repeat surgery after clotting must be heparinized to prevent a similar recurrence. Flushing blood clots from the cava can be fatal.

Two-stage correction for tetralogy of Fallot.

The policy for surgical treatment of tetralogy of Fallot in younger patients is still controversial. Our overall 14-year experience has been reviewed with regard to the factors influencing mortality for both shunts and corrective procedures. An attempt has been made to evaluate our current expected cumulative mortality for two-stage correction in patients under 2 years of age. From November, 1966 through April, 1983, 440 shunts and 647 total corrections were performed. Patients under 2 years of age, and those with unfavorable anatomy and/or physiology, generally underwent two-stage correction. Early correction was occasionally performed in this age group on patients with very favorable anatomy, or in case of early shunt failure. Retrospective standard statistical analysis was carried out in order to evaluate the influences of the year of operation, age, and operative technique on mortality. The overall early mortality of shunt procedures was 5.7% (11.4% below and 3.5% over 6 months of age). Since 1978 it has dropped to 2.8% (4.2% below and 2.1% over 6 months). The Waterston shunt had a higher (7%) operative mortality than the Blalock (3%) or Goretex (2.6%) shunts. The overall early mortality of total corrections was 15.1% (25.2% below and 13.5% over 2 years of age). It has dropped to 6.9% since 1978 (29.9% below and 6.2% over 2 years).(ABSTRACT TRUNCATED AT 250 WORDS)

A Comparison of Blalock-Taussig, Waterston, and Polytetrafluoroethylene Shunts in Children Less Than Two Weeks of Age

Results obtained with Blalock-Taussig, Waterston, and polytetrafluoroethylene (PTFE) shunts were compared in 67 cyanotic infants less than 2 weeks of age. A different shunt was preferably used at each of three institutions. The incidences of early shunt failure (3 out of 21, 14%), mortality after revision of early shunt failure (0 out of 3), and overall hospital mortality (1 out of 21, 5%) were all lowest for the PTFE shunt. Incidence of congestive heart failure secondary to excessive flow was comparable for the Blalock-Taussig and PTFE shunts, both of which were lower than the Waterston shunt. Cumulative probabilities of late shunt adequacy were calculated for hospital survivors. At 1 year, all shunts provided comparable adequate palliation (greater than 80%). Probability of late shunt failure was significantly higher ( p = 0.04) for the PTFE shunt at 3.5 years. Results suggest that the PTFE shunt may be the safest and most effective shunt in neonates, but that elective shunt replacement or total repair may be warranted in the first or second year of life.

Selection of patients with malignant ascites for a peritoneovenous shunt.

Twenty-two patients with intractable malignant ascites who received a peritoneovenous shunt were studied. We found that the peritoneovenous shunt functioned longer in patients whose ascitic fluid was negative for malignant cells. The median shunt survival in alive patients in the negative cytologic group was 140 days compared to 26 days in the positive cytologic group (P = 0.01). The overall survival of these patients was poor, with a median of 32 days. Median survival of patients with positive cytologic results (26 days) was significantly worse than for the cytologically negative group (80 days; P = 0.05). The incidence of tumor emboli, confirmed at autopsy, was estimated to be about 5%. Seventy-five percent of all complications occurred in the group of patients with a positive cytologic result. We conclude that a positive ascites fluid cytologic finding is a relative contraindication to placement of a peritoneovenous shunt since this is associated with early shunt failure, postoperative coagulopathy, infection, and tumor emboli. However, since the serious complication rate is only 4% and tumor emboli rate 5%, peritoneovenous shunting in symptomatic patients with cytologically negative malignant ascites is a useful palliative procedure.