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A balloon embolectomy catheter is effective for removing an embolus, a foreign substance (usually a blood clot) that circulates in the bloodstream until it becomes attached to the wall of a blood vessel. This instrument is particularly effective when used to remove an embolism from an artery. Although balloon embolectomy is generally safe, some complications have been reported, including perforation of the artery, disruption of the vessel wall, damage to the inner lining (intima) of the vessel, development of an abnormal connection between an artery and a vein (arteriovenous fistula), development of an aneurysm (localized widening of the vessel wall) or pseudoaneurysm, and narrowing of the vessel due to hyperplasia of the intima. Various catheters have been designed to reduce these complications. Four balloon embolectomy catheters were evaluated and compared on the basis of their mechanical characteristics. The Multi-Pro catheter was found to be the least likely to perforate a blood vessel since it would require the greatest force to do so. The time it takes for a balloon catheter to empty reflects the ability of the surgeon to rapidly adjust the balloon to changes in the size of blood vessels. One catheter studied, the silicone Becton-Dickinson, required twice as long to empty as the other three catheters evaluated. The effects of the four catheters on blood vessels was studied; the greater the shear force applied, the greater the amount of intimal hyperplasia. There was no difference in the degree of hyperplasia associated with the catheters studied. These results indicate that some brands of catheters allow the surgeon to have more control and are less likely to cause blood vessel injury than other catheters. (Consumer Summary produced by Reliance Medical Information, Inc.)

BACKGROUND: Herniorrhaphies using a foreign body such as mesh can become infected. An experiment was performed in rabbits to compare three methods of antibiotic treatment to prevent the growth of bacteria in mesh-containing wounds. METHODS: This experiment compared preoperative intravenous antibiotics (cefazolin), topical antibiotics applied intraoperatively (bacitracin), and their combination in preventing the quantitative growth of bacteria in a subcutaneous wound containing a polypropylene mesh inoculated with Staphylococcus aureus. The bacteria were inoculated in doses sufficient to deliberately cause the growth of 130.0 [+ or -] 56.4 x [10.sup.4] bacteria per gram of tissue in saline-treated control animals. Quantitative cultures of the mesh and surrounding tissues were obtained 5 days after insertion of the mesh and inoculation of the wound. RESULTS: Experimental data showed that treatment with systemic intravenous antibiotics, topical powdered antibiotics, or their combination all statistically significantly decreased the quantitative cultures grown from the inoculated tissues as compared with saline-treated controls (P

From an engineering point of view, the development of an arterial aneurysm is a classic case of material failure that may involve two factors: excessive applied load and inadequate material strength. The author describes a hypothesis that explains how atherosclerosis could increase the pressure load on the vessel and at the same time decrease the capacity of the wall to bear that load. It will be of interest to learn precisely what the genetic trait is that causes the atherosclerotic aorta to fail structurally in some patients while allowing the vessel to remain intact and develop occlusive lesions in others.

• Studies were performed in vitro on cylindrical segments of 56 canine common carotid arteries, 32 human external iliac arteries, nine internal iliac arteries, and ten common iliac arteries, using purified elastase and purified collagenase. Treatment with elastase caused the canine vessels to dilate but to remain intact. Similar results were obtained with the human vessels, except that treatment with elastase caused only slight dilation. All canine and human vessels treated with collagenase ruptured. We concluded that wall integrity depends on intact collagen rather than elastin. Comparison between external iliac arteries and internal and common iliac arteries showed that the latter vessels exhibited dramatically greater dilatation and compliance changes after treatment with collagenase. This finding corresponds to the greater tendency of aneurysms to develop in internal and common iliac arteries.(Arch Surg 1984;119:405-409)

Non-invasive measurements of the diameter and wall thickness of arteries in vivo combined with recordings of pressure, permit the assessment of some mechanical aspects of arteries in vivo.However, arteries are anisotropic cylinders with complex elastic properties which can only be determined by a detailed evaluation. Many of the parameters required to calculate the anisotropic circumferential elastic modulus cannot be obtained in patients in vivo,or can be obtained only with difficulty.

• Laboratory studies were performed on 509 size 6-0 polypropylene sutures to examine the effects of surgical manipulation on suture tensile strength. Results showed that dragging sutures over the torn edge of the foil package, permanently kinking sutures, or axially twisting them up to four times did not decrease tensile strength. Similarly, the tug exerted by operating room nurses on polypropylene sutures did not decrease their tensile strength. Two manipulations, however, did decrease breaking strength. The presence of a stray knot reduced suture strength 17%, and grasping sutures with DeBakey forceps decreased suture strength in a dose-dependent fashion. When experienced surgeons grasped sutures with forceps out of direct vision, their grasping forces were well below that which alters tensile strength. Nevertheless, these results demonstrate that sutures that have acquired a stray knot should be discarded and that sutures should not be grasped with mechanical devices such as forceps.(Arch Surg 1989;124:665-668)