Vision of relevant technologic progress for the next two decades☆☆☆★★★

Article Outline

• ENABLING VISUALIZATION TECHNOLOGIES
• ACCESS SITE MANAGEMENT
• CONTROL OF THE HEALING RESPONSE
• CONCLUSION
• References
• Copyright

The terms “science” and “technology” are often used interchangeably. In fact, they are quite different. Science is the exploration of theory with the purpose of documenting the validity or invalidity of a theoretic premise. Technology is the application or implementation of proven science for practical purposes. The conversion of science into technology is influenced by multiple factors other than the validity of the science (Table I). These additional influences often determine the direction and ultimate acceptance and viability of a new technology. When applied to surgical therapeutics, old and new technologies can be identified and categorized as devices, procedures, techniques, and instrumentation. As illustrated in Table II, there are potentially 36 possible permutations that can be created by combining new and old devices, procedures, techniques, and instrumentation into new evolutionary technologies. In well-developed countries, cardiac and vascular diseases represent some of the most common and highly visible disease entities that afflict the aged population. As specialists who treat these diseases, we will become highly influential in creating technologies to address these diseases. It is therefore critical that we understand and involve ourselves in the technologic process.

Table I. Important influences on technology

Table II. Technology as applied to surgical therapeutics

36 possible combinations.

A common perception held by both practitioners and consumers alike is that new technology equates with “increased cost.” As we advance technology in our specialty, we must consider an overall net economic impact to avoid adding to health care costs. To be successful, a new technology should—in fact must—demonstrate clinical utility equal or superior to the standard methods that we currently use without significantly increasing cost.

It is interesting to note that government itself has played a role in increasing health care costs. Meeting the requirements and numerous legislative mandates for the purpose of assuring the safety and efficacy of new drugs and devices can add approximately 10% to 50% to total developmental costs. New, less-invasive technology, however, represents the most viable mechanism for controlling and at times even reducing these escalating costs. Table III lists the cost-saving benefits that can be realized by using less-invasive methods. Good technology used appropriately can reduce cost; however, good technology used inappropriately and bad technology both serve to increase cost.

Table III. Less-invasive technology

It has become increasingly important for physicians to understand the relationship between cost and net economic impact (Table IV). It is a serious error to consider only one or two components of the factors that contribute to the net economic impact and interpret that as total cost. For example, the use of new instrumentation may be more expensive than the instruments they replace. If, however, that instrumentation avoids general anesthesia, eliminates critical care time, and reduces length of stay, it is quite likely to be cost-effective. As surgeons, it is important that we recognize that surgical supply costs account for approximately 6% of hospital charges. Materials managers are sometimes awarded incentives based on the supply cost savings they produce. The purchase of an unfamiliar or inferior instrument may actually increase costs by requiring the use of multiple devices as a result of the clinician's unfamiliarity with a new product or as a result of the product's inferior quality and reliability. Both situations negate any negligible cost-saving benefits that were hoped to have been gained by using a less expensive, but overall poor, substitute for the standard, slightly more expensive alternative. In addition, the complications that are often associated with use of an unfamiliar instrument, suture, or implant may lead to prolonged hospital stays and even increased mortality rates, which further increase monetary costs and the patient-related costs to life and limb. When these scenarios are carefully considered, it becomes clear that obtaining the advice of physicians in medically related purchase decisions is critically important. Without this input significant savings are not likely to be realized.

Table IV. Procedure economics

Health technology advances through the development of drugs, procedures, instruments, techniques, implants, and services. It is important to appreciate that these advancements occur in combination, and often as a result of one another. For example, transplantation is possible because of the availability of improved techniques and antirejection drugs.

Less-invasive techniques fall into two categories—diagnostic and therapeutic. I predict that all less-invasive methods will see increasing clinical application and become the standard of care in the future. Three areas that deserve particular mention are enabling visualization technologies, access site management, and controlling the healing response.

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ENABLING VISUALIZATION TECHNOLOGIES 

The ability to combine diagnostic techniques with therapeutic techniques has already occurred in the field of coronary interventions. This concept will be extended to the management of peripheral vascular disease. Four visualization methods that will allow diagnosis and therapy to become combined into one effort are illustrated in Table V.

Table V. Enabling visualization technologies for endovascular procedures

Current C-arm fluoroscopy units allow accurate diagnosis for the purposes of selecting and implementing appropriate therapeutic interventions. Fixed overhead units are available and offer some advantages when dealing with more advanced or experimental techniques. In the majority of routine applications of endovascular technology, portable C-arm fluoroscopy with road-mapping capability and hard copy are safe and cost-effective. These units, when used in conjunction with other preoperative noninvasive diagnostic studies, can and should be used to corroborate the anatomic diagnosis. Fluoroscopy indicates to the surgeon whether intervention is required and which procedures can be performed; it also aids in the selection of tools needed to accomplish the intervention. As a real-time guide during therapy, intraluminal visualization with ultrasonography, angioscopy, or both will be used with increasing frequency. Like fluoroscopy, these two visualization methods will provide therapeutic guidance, but in addition they will document the completeness of therapy. An incentive for cost savings will serve to accelerate the process of combining diagnostic procedures with therapeutic treatment methods.

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ACCESS SITE MANAGEMENT 

The development of percutaneous access by Seldinger¹ significantly accelerated the clinical utility and acceptance of cardiac catheterization. Sones² is credited with documenting the safety of coronary visualization. In this procedure he gained access via direct cutdown on the brachial artery. Later, Judkins³ popularized the femoral percutaneous approach for intracoronary visualization. This approach was made possible by the introduction of specialized catheters that could be preformed in various shapes. With the development of techniques for coronary therapeutic interventions, catheter systems with a larger diameter are needed. Many of these advanced therapeutic interventions are associated with the use of anticoagulant, antiplatelet, and fibrinolytic drugs. Antiplatelet and fibrinolytic drugs have resulted in a significant increase in the frequency and magnitude of femoral puncture site complications.

The standard routine for puncture site management typically involves direct compression over the puncture site during prolonged periods of bed rest and immobilization. Frequent observation of the access site is required by trained personnel. Complications associated with puncture site management according to the method described to achieve access site hemostasis are responsible for more than 15% of the costs associated with advanced therapeutic interventions.

Complications related to femoral artery access sites include hematoma, arteriovenous fistula, rebleeding, pseudoaneurysm, and local and systemic infection. In situ thrombosis, distal embolization, anemia requiring transfusion, and causalgia are additional significant untoward events. Recently developed access site closure devices appear to eliminate many of the problems and complications associated with percutaneous punctures and offer an optimistic outlook for advancing percutaneous procedures in the future.

The VasoSeal (Datascope Corp., Montvale, N.J.) and the Angio-Seal (Sherwood-Davis & Geck, St. Louis) are two collagen closure devices used for puncture site management that have recently undergone clinical trials. The technology used in these devices is illustrated in Fig. 1, Fig. 2, respectively.

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• Fig. 1. 

  Illustration of VasoSeal vascular hemostasis device providing puncture site sealing by application of collagen to outside of femoral artery (photo courtesy of Datascope Corp., Montvale, N.J.).

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• Fig. 2. 

  Illustration of Angio-Seal device mode of action used to seal femoral access site. After absorbable anchor has been inserted into artery lumen (A), it is withdrawn by pulley type of absorbable suture until secure at artery wall. Absorbable collagen sponge is then deployed outside artery, compressing anchor against vessel surface to create a seal (B). All components are absorbed in 60 to 90 days (photo courtesy of Sherwood-Davis & Geck, St. Louis).

These devices are appropriate for specific clinical applications, specifically the closure of percutaneous angiography access sites. Both devices use collagen to seal within or on either side of the puncture site. Despite offering a positive advantage to managing the percutaneous access site, the need for prolonged bed rest and immobilization after the procedure is not totally eliminated.

Although standard surgical repair of puncture site complications is effective, it is not routinely performed because surgical closure exposes patients to an unnecessary operation and is expensive.

Devices that accomplish percutaneous closure with a suture technique have been developed.⁴ These devices are capable of closing puncture sites ranging in size from 5F to 11F. Prostar (Perclose, Inc., Menlo Park, Calif.) is an instrument designed to effectively close punctures made by the larger 9F through 11F sheaths. The instrument is exchanged for the femoral sheath at the completion of the intervention. An illustration of the device in use is shown in Fig. 3.

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• Fig. 3. 

  Illustration of Prostar percutaneous vascular surgical closure device. A, Sheath loaded with four needles carrying sutures is placed into artery; B, needles are deployed through artery wall as device handle is pulled upward; C, square knots are tied in each suture and delivered to artery surface with knot pusher. Complete hemostasis is achieved with percutaneous approach (photo courtesy of Perclose, Inc., Menlo Park, Calif.).

Additional larger sizes that offer the potential for the percutaneous introduction of stent grafts in some circumstances are under evaluation. There is an obvious limit to the size of a percutaneous puncture site that can be closed with the percutaneous closure technique. Percutaneous suture closure of arterial puncture sites has undergone clinical evaluation and has proved to be extremely effective. To date, experience with this device, although limited, has been very positive. The approach allows immediate patient mobilization in the presence of continued uninterrupted anticoagulant therapy. Shortened hospital recuperations have resulted, and early restudy through the same limb access site is possible. It is likely that with additional larger-sized instruments and an increased awareness of the improved puncture site management techniques, the applications of percutaneous mediated procedures for both occlusive and aneurysmal disease will expand.

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CONTROL OF THE HEALING RESPONSE 

An inability to control the healing process is responsible for most occlusive failures seen in revascularization procedures. Early failures that occur before 6 months are often caused either by an inadequate initial procedure, by thrombosis at the injury site, or both. Failures beyond 6 months are the result of a healing response at the area of vascular tissue injury. An excessive fibroblastic response at these sites results in narrowing and ultimate occlusion. Smaller vessels (<5 mm in diameter) are particularly susceptible to these types of late failures. Devices are being developed that are designed to provide local deposition of pharmacologic agents to the arterial wall, residual arterial wall, and surrounding tissue with catheter techniques. The slow release of therapeutic compounds developed to inhibit the healing process is currently being evaluated clinically. The list of inhibitory agents includes antiplatelet compounds, antithrombotic drugs, and antihealing drugs. It is likely that in the future these drug entities will be used at all anastomotic sites and areas of endoluminal disease manipulated by catheter systems.

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CONCLUSION 

When envisioning the technologic process, we must “think young” and consider the impossible. This mindset is best achieved in an environment where innovators consider the unachievable as being possible. If technology is to be advanced, we must make every effort to allow new ideas to be nurtured, refined, clinically tested for safety and efficacy, and evaluated in all aspects. This critical evaluation should also carefully consider the technology's net economic impact. I believe that in the future our vascular specialty will witness a decided shift toward less-invasive technology in our surgical approaches. Minimally invasive catheter-based interventions offer a real potential to provide equal or superior clinical outcomes at reduced costs.

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References 

1. Seldinger S. Catheter replacement of the needle in percutaneous arteriography, a new technique. Acta Radiol. 1953;39:368–376
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2. Sones F, Shurey E. Cine coronary arteriography. Mod Con Cardiova Dis. 1962;31:735
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3. Judkins MP. Selective coronary arteriography: Part I. A percutaneous transfemoral technic. Radiology. 1967;89:815
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4. Vetter JW, Ribeiro EE, Hinohara T, Carrozza JP, Simpson JB. Presented at the 67th Scientific Session of the American Heart Association Meeting, Dallas, Suture-mediated percutaneous closure of femoral artery access sites in fully anticoagulated patients following coronary interventions. Nov. 14-17, 1994; [abstract[
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