[Early and mid-term results after 17 mm St Jude Regent mechanical valve replacement in 44 patients with small aortic root].

OBJECTIVE: To analyze the changes in the cardiac function after St. Jude Regent mechanical valve replacement and assess the prosthesis-patient matching. METHODS: From October 2007 to March 2009, 44 patients received implantation of 17 mm St. Jude aortic prostheses in our hospital. The patients were followed up for clinical symptoms, signs, electrocardiogram (ECG), echocardiogram and cardiac functions, and the results were compared with those of randomly selected 44 patients receiving 21 mm St. Jude aortic prostheses. RESULTS: In 17 mm St Jude Medica Regent valve group, 8 patients presented with ECG ST segment changes, 3 complained of chest tightness, 3 had occasional chest pain and discomfort, and 8 had grade II and 4 grade III cardiac function. In 21 mm St Jude Medical Regent valve group, 6 patients had ECG ST segment changes, 2 complained of chest tightness, 2 reported occasional chest pain and discomfort, 11 had grade II and 2 grade III cardiac function. No significant differences were found in these indices between the two groups (P=0.32). Compared with those before operation, the two groups showed significant improvements in the left ventricular end-diastolic diameter, left ventricular posterior wall thickness, left ventricular mass index, and aortic pressure gradient (P<0.05). A significant increase in the left ventricular ejection fraction occurred 6-12 months after operation, but without statistical difference between the two groups (P>0.05). CONCLUSION: For underweight patients (<60 kg) and those with small body surface area (<1.6 cm(2)), 17 mm St. Jude Medical Regent valve prosthesis may produce good therapeutic effect, and some indices are even close to those after placement of 21 mm St. Jude Medical Regent valve prosthesis. No obvious prosthesis-patient mismatch occurs after the placement of the 17 mm valve prosthesis and aortic valve ring expansion is not necessary.

Simultaneous determination of 42 organic chemicals in bottled water by combining C18 extraction disk with GC-MS and LC/MS/MS technique.

A method for the determination of 42 hazard residues required by 'Japan Positive List System' in bottled water was described. Hazard compounds in bottled water were extracted with a solid phase extraction step using C18 disks. Determination was carried out by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography-tandem mass spectrometry (LC/MS/MS). The disk extraction has high throughput which is well adapted to isolate and enrich these compounds from large volumes of water. For the water sample spiked at three concentration levels (LOQ, 4 times LOQ and 8 times LOQ), the recoveries of all analytes ranged between 65% and 120% with a relative standard deviation<24% (n=8).