PubMed · 7300271
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P A Prelock, J M Panagos. 1981. The middle ground in evaluating language programs.. https://doi.org/10.1044/jshd.4604.436
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OBJECTIVE: The most widely implanted prosthetic valves are the mechanical bileaflets, most of which have good forward flow hemodynamics. However, recent clinical experiences illustrate the importance of understanding the flow structures generated within the hinge. The purpose of this study was to evaluate the hinge-flow dynamics of two new variations of a 17-mm St Jude Medical bileaflet valve: the Hemodynamic Plus and the Regent (St Jude Medical, Inc, St Paul, Minn). METHODS: Clinical quality reproductions of the valves were manufactured with clear housings. Laser Doppler velocimetry velocity and turbulent shear stress measurements were conducted within the hinge and thumbnail regions of the valves. RESULTS: In the 17-mm Hemodynamic Plus hinge, a rotating flow structure developed in the inflow pocket during forward flow. During systole, velocities through the hinge pocket reached 0.70 m/s, and the turbulent shear stress reached 1000 dynes/cm(2). In the thumbnail, forward flow velocities ranged from 1.4 m/s to 1.7 m/s. In the 17-mm Regent hinge, a rotating flow structure partially developed in the inflow pocket during forward flow. During systole, velocities through the hinge pocket reached 0.75 m/s, and the turbulent shear stress reached 1300 dynes/cm(2). In the thumbnail, forward flow velocities ranged from 1.0 m/s to 1.3 m/s. CONCLUSIONS: The active leaflet motion through the St Jude Medical hinge creates a washout pattern that restricts the persistence of stagnation zones and thus may be a contributing factor to its successful clinical performance. The hinge and thumbnail flow dynamics of the 17-mm Regent valve are at least equivalent to, and possibly superior to, those of the 17-mm Hemodynamic Plus valve.
There are two major problems including indications and techniques in video-assisted lung resection for lung cancer. The current technique of video-assisted lung resection have various troublesome procedures as compared with conventional open thoracic surgery. We have designed a new thoracoscopic instrument as a ligation device. Between September 1997 and August 1999, 15 patients with early lung cancer underwent video-assisted lobectomy (VAL). In 5 patients, VAL was performed through skin incisions of 3 cm using this new device and at extraction of the resected lung the skin incision was elongated minimally (Group A). In 10 patients, a skin incision of 6-8 cm was made enough to perform VAL without the new device at the beginning of the operation (Group B). Total length of skin incisions (TLS) and total postoperative pleural discharge (TPD) were measured. TLS was 7.2 +/- 1.47 cm in group A, 11.9 +/- 4.50 cm in group B (p = 0.029). TPD was 492 +/- 256 ml in group A, 1.132 +/- 591 ml in group B (p = 0.032). TPD might be thought as an index of invasion of VAL and it was difficult to decrease TPD significantly. The new device made it possible to feel the ligature tension when the device was in touch with the chest wall. In a result, the device improved technical procedure of VAL and contributed toward less invasive surgery.