Percutaneous fetoscopic tracheal balloon occlusion in sheep.

BACKGROUND: In order to minimize maternal trauma from current techniques for temporary fetoscopic tracheal occlusion, we tried to develop a percutaneous fetoscopic technique in sheep. METHODS: In nine ewes between 77 and 128 days of gestation, the amniotic cavity was entered percutaneously. Each fetus was positioned and the feasibility of fetal laryngoscopy and percutaneous fetoscopic tracheal balloon occlusion was assessed. RESULTS: Percutaneous intraamniotic access, fetal positioning, oropharyngeal sheath insertion, and fetoscopic laryngoscopy were achieved in all nine fetal sheep. Following some technical modifications to the working channel of the fetoscope, percutaneous fetoscopic tracheal balloon occlusion was successfully achieved in the last seven sheep. CONCLUSION: Percutaneous fetoscopic balloon occlusion of the fetal trachea can effectively and safely be achieved in sheep. Because intraamniotic spatial relationships, fetal position, and umbilical cord length are technically less favorable in sheep, our operative techniques might be feasible in humans even if difficult intraamniotic conditions are encountered.

Percutaneous fetoscopic patch coverage of experimental lumbosacral full-thickness skin lesions in sheep.

BACKGROUND: In order to minimize maternal trauma from open fetal surgery for prenatal coverage of fetal myelomeningoceles in humans, we assessed the feasibility of a percutaneous fetoscopic approach in sheep. METHODS: In seven ewes between 90 and 100 days of gestation, the amniotic cavity was entered percutaneously. Each fetus was postured and a full-thickness skin lesion was created in the lumbosacral region. Then, the feasibility of covering this lesion with a patch and fetal skin by standard endoscopic suturing techniques (n = 3) or robot assistance (n = 4) was assessed. RESULTS: Percutaneous fetoscopic patch and skin coverage of the full-thickness skin lesion was achieved in six of the seven fetal sheep. Five fetuses survived gestation and were delivered healthy. CONCLUSIONS: Percutaneous fetoscopic posturing and patch coverage of lumbosacral full-thickness skin lesions can effectively and safely be achieved in sheep. This approach promises to provide a substantial reduction of maternal trauma from fetal surgery for myelomeningoceles.

Naloxone improves functional recovery of myocardial stunning in conscious dogs through its action on the central nervous system.

This study tests the hypothesis that naloxone, but not its quarternary salt, naloxone methiodide (which does not enter the central nervous system), improves recovery from myocardial stunning in conscious dogs. Twenty dogs were chronically instrumented for measurement of heart rate, left atrial, aortic and left ventricular pressure (LVP), LV dP x dtmax(-1) and myocardial wall thickening fraction (WTF). Regional myocardial blood flow was determined with coloured microspheres. Occluder around the left anterior descending artery (LAD) allowed induction of reversible LAD ischaemia. Each of the 20 dogs underwent two LAD ischaemic challenges. Experiments (performed on separate days, in crossover fashion) were: (i) 10 min of LAD occlusion after application of naloxone 63 microg kg(-1) or naloxone methiodide 63 microg kg(-1) and (ii) occlusion without naloxone or naloxone methiodide. WTF was measured at baseline and until complete recovery occurred. LAD ischaemia significantly reduced LAD WTF with (mean (SD) 54 (15)% lower than baseline) and without naloxone (55 (16)% lower than baseline), without significant haemodynamic differences. Between I to 30 min of reperfusion, WTF was significantly higher with naloxone (P < 0.05). There was no difference in WTF with or without naloxone methiodide. We conclude that naloxone improved recovery from myocardial stunning in conscious dogs, and that this was centrally mediated.

Hemin, inducer of heme-oxygenase 1, improves functional recovery from myocardial stunning in conscious dogs.

OBJECTIVE: To examine the effects of pretreatment with hemin, an inducer of the potential antioxidative enzyme heme-oxygenase 1 (HO-1) or heat-shock protein 32, on myocardial stunning. DESIGN: Randomized animal study. SETTING: Animal laboratory of a university hospital. PARTICIPANTS: Chronically instrumented mongrel dogs (n = 44). INTERVENTIONS: Dogs underwent chronic instrumentation for measurement of hemodynamics and myocardial wall thickening fraction (WTF). Experiments with 12 dogs were performed on separate days in a crossover fashion: (1) 10 minutes of left anterior descending (LAD) coronary artery occlusion after application of hemin (9 mg/kg/d) for 1 week and (2) 10 minutes of LAD coronary artery occlusion without hemin pretreatment. In control experiments (n = 32), the reversible induction of HO-1, using gel electrophoresis and Western blotting, was determined. MEASUREMENTS AND MAIN RESULTS: WTF was measured as a baseline value before hemin administration and at predetermined time points until complete recovery from stunning. LAD artery occlusion caused a significant reduction in the WTF in the LAD-perfused area with and without hemin, without significant hemodynamic changes. At all time points, after 1 minute of reperfusion, the WTF as percentage of baseline values was significantly higher after hemin pretreatment (p < 0.05). Baseline WTF values were reached after 24 hours with and after >48 hours without hemin pretreatment (p < 0.05). CONCLUSION: Hemin pretreatment attenuates myocardial stunning in conscious dogs.