This and that: management of Tetralogy of Fallot and pulmonary vein stenosis in an infant-a case report.

BACKGROUND: Tetralogy of Fallot (TOF) is the most common congenital cyanotic cardiac lesion. Pulmonary vein stenosis occurs much less commonly and remains difficult to manage. It is exceedingly uncommon for a patient to have both lesions. This case highlights the diagnostic and management difficulties in an infant with these two lesions. CASE SUMMARY: The patient is a 4-month-old female infant with a history of TOF status post right ventricular outflow tract stent placement who presented after a hypoxaemic event at home to 40% SpO2. Computed tomography angiography demonstrated previously undiagnosed pulmonary vein stenosis of all four veins. She underwent multiple catheter-based palliations including balloon dilations and stent placements in each pulmonary vein in order to maximize her chances of successful definitive repair. She underwent successful repair of her TOF and pulmonary vein stenosis at ten months of age. DISCUSSION: The combination of TOF and pulmonary vein stenosis is not common, but when these lesions co-occur, they present a significant dilemma in determining the timing of surgery in order to optimize the odds of a successful outcome. This case demonstrates that serial catheter-based procedures can be valuable tools in minimizing pre-operative risk factors and highlights one strategy in determining timing of definitive surgical repair.

Addition of hand-blended generic tobramycin in bone cement: effect on mechanical strength.

This study compared the mechanical strength of commercially prepared antibiotic bone cement (Simplex With Tobramycin; Stryker, Mahwah, NJ), cement with generic tobramycin (Pharma-Tek, Huntington, NY) blended in by the orthopedic nursing staff, and standard nonantibiotic bone cement. The results showed an approximate 36% decrease in the strength of the cement with hand-mixed generic tobramycin, while the commercial antibiotic cement remained unchanged relative to the nonantibiotic control. These results indicate the mechanical properties of bone cement can be severely compromised by hand-mixing antibiotics into bone cement at the time of surgery.

The strength of acrylic bone cement cured under thumb pressure.

In this investigation, the static tensile strength of bone cement was quantified after mixing it in an open bowl or in a commercially available vacuum mixer and molding it under pressures consistent with values obtained by finger/digital application, as it is used in surgery. Pressure, held for a brief time span on cement in its lower viscosity state, has been demonstrated to increase penetration of the cement into bone. Clinically, bone cement is pressurized by digital pressure, specialized instruments, or by implant design. Specimens were cured under constant pressures of up to 100kPa, which is in the range reported for thumb pressurization of plugged proximal femurs and instrumented pressurization of acetabular sockets. The results showed that application of constant pressure during the polymerization of open bowl mixed bone cement significantly improved its mechanical properties. Application of 100kPa constant pressure to the open bowl mixed bone cement while it cured increased its ultimate strength to a value similar to vacuum mixed cement. Curing under pressure showed no significant effect on the tensile properties of vacuum mixed cement. Curing under pressure did not significantly reduce the size of the largest pores in the tensile specimens.

Antibiotic bone cement for the treatment of Pseudomonas aeruginosa in joint arthroplasty: comparison of tobramycin and gentamicin-loaded cements.

One hundred clinical isolates of Pseudomonas aeruginosa were collected from 22 medical centers throughout Europe and were challenged with two aminoglycoside-loaded bone cements, employing a modified in vitro Kirby-Bauer susceptibility model. The results of this study show that Simplex P with tobramycin exhibits antibacterial activity against 98% of the strains tested, compared to 93% for Palacos with gentamicin. Additionally, for strains that were susceptible to the antibiotic bone cement formulations, the average zone of inhibition produced around the tobramycin-loaded cement disks was approximately 25% greater than that seen around the gentamicin-loaded cement disks. This difference was statistically significant (p << 0.01). Tobramycin-loaded bone cement is therefore the preferred formulation when addressing Pseudomonas aeruginosa in septic joint arthroplasty.