Hyperammonemic coma in an ornithine transcarbamylase mutation carrier following antepartum corticosteroids.

Women who are carriers of the ornithine transcarbamylase (OTC) mutation are at risk for developing hyperammonemia during the postpartum period and at times of metabolic stress. We present a unique case of hyperammonemic coma occurring in an OTC mutation carrier during the antepartum period. Multiple factors, including the administration of antenatal corticosteroids, likely precipitated this critical condition. Clinicians should be aware of this life-threatening clinical presentation and be prepared to identify, treat, and prevent hyperammonemia in affected individuals.

Intravenous dexmedetomidine as an adjunct for labor analgesia and cesarean delivery anesthesia in a parturient with a tethered spinal cord.

For parturients desiring labor analgesia who have contraindications to neuraxial techniques, intravenous opioid-based patient-controlled analgesia (IVPCA) offers a reasonable alternative, although incomplete analgesia and maternal and neonatal respiratory depression can occur. Dexmedetomidine, a highly selective alpha(2) agonist with negligible placental transfer, may be a valuable adjunct to IVPCA by providing additional analgesia without the respiratory depression associated with increasing opioid usage. The successful use of a dexmedetomidine infusion as an adjunct to unsatisfactory fentanyl IVPCA is reported in a 31-year-old parturient with spina bifida occulta and a tethered spinal cord reaching L5-S1. Dexmedetomidine significantly improved the analgesic quality; increased sedation was observed, but the patient was easily rousable to verbal stimuli. No episodes of maternal hypotension or bradycardia, or fetal heart rate irregularities occurred. Cesarean delivery was required for prolonged first stage of labor and presumed chorioamnionitis; it was conducted under general anesthesia during which the dexmedetomidine infusion was continued. A healthy baby boy was delivered with normal Apgar scores and no discernible neurobehavioral or other deficits.

Chronic evaluation of orthotopically implanted bileaflet mechanical aortic valves in adult domestic sheep.

This study was intended to develop a technically feasible and reproducible model for chronic hemodynamic and mechanical evaluation of orthotopically implanted bileaflet mechanical aortic valves in adult domestic sheep. Three adult sheep (mean age 22 weeks, mean weight 76 kg) underwent aortic valve replacement using 19-mm bileaflet aortic valves. Standard cardiopulmonary bypass techniques were followed, including mild hemodilution, systemic hypothermia, and cardioplegic arrest. After performing a left fourth intercostal thoracotomy, the valves were placed using interrupted 3-0 Ticron (Davis + Geck) inverted mattress sutures through a transverse aortotomy. The average cardiopulmonary bypass time was 58+/-1 min. No chronic anticoagulation was used. There were no surgical complications. All three animals (100%) remained clinically well until elective sacrifice after postoperative day 150. The average cardiac output for the animals at sacrifice was 3.8+/-1.0 L/min. The mean aortic ejection velocity was 304.7+/-47.3 cm/s and the mean pressure gradient was 24.6+/-6.7 mm Hg. There was no clinically significant thrombus formation or paravalvular leaks. Thus, we have demonstrated that it is technically feasible to orthotopically implant mechanical aortic valves in sheep. There are several features that contribute to the success of this model, including use of a transverse aortotomy, adequate de-airing, and the use of mild hemodilution during bypass. We believe that this model is reproducible and can be used to study other valve designs. In addition, this model allows for site-specific preclinical assessment of new or modified mechanical heart valves.

Long-term evaluation of orthotopically implanted stentless bioprosthetic aortic valves in juvenile sheep.

The aim of this study was to develop a technically feasible and reproducible model for chronic evaluation of stentless bioprosthetic aortic valves implanted orthotopically using juvenile domestic sheep. This report summarizes the results of a study conducted to assess orthotopically placed 19-mm stentless aortic bioprosthetic valves. Twenty-seven juvenile sheep underwent aortic valve replacement. Standard cardiopulmonary bypass techniques were followed. The average cardiopulmonary bypass time was 73 min. No chronic anticoagulation was used. There were two deaths (7%) due to surgical complications. In the remaining 25 experiments, 11 animals (41%) died prior to the scheduled sacrifice on postoperative day 150. One early death occurred due to coccidiomycosis infection, one due to technical error, one due to pulmonary embolus, four due to prosthetic annular size disproportion, and four due to thrombi. The remaining 14 animals (52%) underwent left and right heart catheterization, angiography, echocardiography, and sacrifice after postoperative day 150. The average weight of the sheep at elective sacrifice was 60 kg (mean weight gain 12.5 kg). The average cardiac output for the sacrificed animals was 5.1 L/min. The mean velocity of blood across the aortic valve for the sacrificed animals was 317 cm/s and the mean pressure gradient was 26.2 mm Hg. Two features suggest that this model may have broad application. First, we have demonstrated that it is technically feasible to evaluate orthotopically placed stentless bioprosthetic aortic valves in growing sheep. Second, the aortic root size of the juvenile sheep allows for implantation and evaluation of a human size aortic valve (19 mm). We believe that this model is reproducible and can be used to study stentless valve designs.

Surgical therapy for pulmonary aspergillosis in immunocompromised patients.

BACKGROUND: Medical management for invasive pulmonary aspergillosis (IPA) is often unsatisfactory. Antifungal therapy may be unable to eradicate IPA in the immunocompromised or neutropenic patient. METHODS: We retrospectively reviewed the surgical management of IPA in 13 immunocompromised patients at our institution. Twelve patients underwent perioperative bone marrow transplantation (4 autologous, 8 allogenic). All 13 patients received antifungal therapy. Eleven patients were neutropenic at the time of operation. RESULTS: The mean interval from diagnosis of aspergillosis to operation was 42 days (range, 3 to 135 days). Eighteen operations were performed on the 13 patients. Seven patients had resections from multiple pulmonary sites, whereas 6 had a single lesion resected. The average lesion resected was 3.7 cm in greatest diameter (range, 1 to 9 cm). After a mean follow-up of 21 months (range, 0 to 9 years), 3 patients (23%) are alive with no evidence of aspergillosis, 6 patients (46%) died without evidence of aspergillosis, and 4 patients (31%) died secondary to aspergillus infection. All 4 patients who died of aspergillus infection received an allogenic bone marrow transplantation. Two patients with direct extrapulmonic extension of IPA at time of operation died of recurrent aspergillus infections. Three of 4 patients who died of aspergillus infection had an absolute neutrophil count less than 1,300 cells/microL at time of operation. The mean absolute neutrophil count of the patients who cleared the aspergillus infection was 5,538 cells/microL. The mean survival of allogenic bone marrow transplant recipients was 5.2 months, and for recipients of autografts was 51.4 months. CONCLUSIONS: In this series, surgical resection of IPA cleared the aspergillus infection in 69% of the patients. Neutropenia, extrapulmonic extension of IPA, and allogenic bone marrow transplantation may predict a worse prognosis. Surgical resection of IPA in immunocompromised patients is an effective form of therapy in a properly selected patient population.