Human cadavers to evaluate prototypes of minimally invasive surgical instruments: A feasibility study.

BACKGROUND: New technology should be extensively tested before it is tried on patients. Unfortunately representative models are lacking. In theory, fresh frozen human cadavers are excellent models. OBJECTIVE: To identify strengths and weaknesses of fresh frozen human cadavers as research models for new technology prior to implementation in gynecological surgery. METHODS: During pre-clinical validation studies regarding the MobiSep uterine manipulator, test procedures were performed on fresh frozen cadavers. Both the experimental setup as the performance of the prototype were assessed. RESULTS: Five tests including six human cadavers were performed. Major changes were made to the MobiSep prototype design. The cadavers of two tests closely resembled surgical experiences as found in live patients. The anatomy of 4 of the 6 cadavers was not fully representative due to atrophy of the internal genitalia caused by age and due to the presence of pathology such extensive tumorous tissue. CONCLUSION: The cadaver tests provided vital information regarding design and functionality, that failed to emerge during the in-vitro testing. However, experiments are subject to anatomical uncertainties or restrictions. Consequently, the suitability of a cadaver should be carefully assessed before it is used for testing new technology.

Coronary anastomotic devices: blood-exposed non-intimal surface and coronary wall stress.

OBJECTIVE: This study compares the area of blood-exposed non-intimal surface in device-constructed anastomoses with the conventionally sutured anastomosis and examines the technical feasibility of 0 blood-exposed non-intimal surface anastomosis configurations. METHODS: In the device-constructed anastomosis, blood-exposed non-intimal surface was estimated in all anastomosis configurations identified in truly new (ie, nonduplicate and nonrelated) patent applications and in anastomotic devices recently introduced by several institutions. In the sutured anastomosis, blood-exposed non-intimal surface area was estimated by analysis of previously investigated anastomoses. In 0 blood-exposed non-intimal surface anastomosis configurations, finite element modeling was used to calculate coronary wall stress. RESULTS: By the end of 2001, 57 truly new applications for the distal coronary anastomosis had been published, categorized in 11 types of anastomosis configurations. The tissue blood-exposed non-intimal surface area (ie, non-intimal tissue surface area) ranged from 0 to 6 mm(2). Approximate total blood-exposed non-intimal surface areas (ie, sum of tissue blood-exposed non-intimal surface and foreign body surface area) in recent devices are 80 mm(2) (GraftConnector, Jomed, Helsingborg, Sweden); 33 mm(2) (Magnetic Vascular Positioner rings, Ventrica, Inc, Fremont, Calif); 4.3 mm(2) (distal connector of St Jude Medical, Inc, St Paul, Minn); and 0.3 mm(2) (Crinoline frame, University Medical Center Utrecht/Delft University of Technology, The Netherlands). The sutured anastomoses, in contrast, contained approximately 1.3 mm(2) blood-exposed non-intimal surface area. The mean peak porcine coronary wall stress in 0 blood-exposed non-intimal surface anastomosis configurations with greater than 90 degrees arteriotomy edge eversion ranges from 0.4 to 0.8 N/mm(2) compared with the mean porcine coronary tear stress of 0.8 N/mm(2). CONCLUSIONS: In recently introduced devices for clinical use, the total blood-exposed non-intimal surface area ranges from 4.3 to 80 mm(2) compared with 1.3 mm(2) in sutured anastomoses. The blood-exposed non-intimal surface area depends on anastomotic orifice size, wall thickness, and bonding components' location and size. Deforming the coronary wall to most of the 0 blood-exposed non-intimal surface anastomosis configurations leads to dangerously high stress concentrations in the coronary arteriotomy corners.

Sutureless coronary anastomosis with an anastomotic device and tissue adhesive in off-pump porcine coronary bypass grafting.

OBJECTIVE: In the search for a facilitated coronary artery anastomosis, we assessed the feasibility of a hybrid anastomosis technique that used a prototype anastomotic device with an extraluminal frame (crinoline-like) and octyl-cyanoacrylate adhesive. METHODS: During off-pump coronary artery bypass grafting in pigs (n = 8), a left internal thoracic artery-right coronary artery anastomosis was constructed and evaluated during the operation and at 5 postoperative weeks. The anastomosis was examined by flow measurement, angiography, intraluminal cast geometric analysis, and histologic analysis. RESULTS: Anastomosis construction required 6.2 +/- 1.3 minutes (mean +/- SD). At 5 weeks all anastomoses were fully patent, with minor anastomotic diameter narrowing (median 16%, 15th-85th percentile 16%-26%). After 30-second graft occlusion, median peak hyperemic flow response was 5.0 (15th-85th percentile 4.4-6.5). As a result of complete, streamlining filling of anastomotic wall recesses by neointima formation, more intimal hyperplasia was found in the crinoline-adhesive anastomoses than in sutured control anastomoses. No excessive, lumen-narrowing neointima formation was observed, however. CONCLUSIONS: The hybrid coronary anastomosis technique was feasible without any need for dedicated application tools. If technical improvements can be realized, the hybrid technique may provide an alternative to manual suturing.