- Email: [email protected]
Acquisition of endovascular skills for obstetrician-gynecologists
Journal of Minimally Invasive Gynecology (2006) 13, 155–160
Acquisition of endovascular skills for obstetriciangynecologists Bruce McLucas, MD From the Department of Obstetrics and Gynecology, University of California-Los Angeles, Los Angeles, California. KEYWORDS: Training; Endovascular; Embolization; Gynecology
Abstract STUDY OBJECTIVE: To identify skills not part of the training of obstetrician-gynecologists that are needed to perform endovascular procedures, especially uterine artery embolization. DESIGN: Literature review of known skills necessary to perform endovascular procedures. RESULTS: Important areas of endovascular skills are as follows. Understanding of the modern C-arm image intensifier is basic to performing endovascular procedures safely for the patient, physician, and others in the procedure room. Many states require physicians to obtain a Fluoroscopy Supervisors Permit when doing such interventions. Arteriotomy begins every endovascular procedure. Physicians must understand catheter manipulation and selection, and the use of microcatheters. An understanding of the pelvic arterial anatomy will help the surgeon identify the uterine arteries. Once in the uterine artery, the surgeon must understand how to successfully embolize the artery. As in any surgery, prevention of complications is important as well as management of complications once they arise. CONCLUSION: Obstetrician-gynecologists should plan on devoting a year for the acquisition of skills needed to perform endovascular procedures. Methods of acquiring such skills include simulator training, animal laboratory procedures, and observation of live procedures. Didactic courses will give physicians an overview of endovascular procedures. © 2006 AAGL. All rights reserved.
In order to be certified as confident to perform uterine artery embolization (UAE), physicians must, among other requirements, perform approximately 100 UAE procedures. Obtaining endovascular training is not exclusive to obstetrician-gynecologists. Many specialties have had to acquire skills in endovascular surgery, with cardiologists learning to perform angioplasty and vascular surgeons learning to place endovascular stents.1,2 Endovascular credentialing issues for obstetrician-gynecologists have been addressed in a previous paper.1 Many obstetrician-gynecologists have not had contact Corresponding author: Bruce McLucas, MD, 100 UCLA Medical Plaza, Suite 310, Los Angeles, CA 90024. E-mail: [email protected] Submitted August 25, 2005. Accepted for publication December 2, 2005.
1553-4650/$ -see front matter © 2006 AAGL. All rights reserved. doi:10.1016/j.jmig.2005.12.008
with interventional procedures or with the radiologists who perform them. Since the widespread success of UAE,3 many patients have requested this procedure to treat symptomatic myomata. Embolization is a reproducible technique offering a high rate of success4 in settings all over the world.5 Traditionally, UAE has been performed by interventional radiologists. These physicians finished a radiology residency and then took a 1-year fellowship to acquire their skills.6 Obstetrician-gynecologists offer their patients the possibility of continuity of care that radiologists cannot. At the current stage of development of endovascular procedures for obstetrician-gynecologists, physicians desiring to acquire skills will need to seek mentoring programs with qualified physicians already performing embolization. This paper seeks to outline the skills needed for the perfor-
156
Journal of Minimally Invasive Gynecology, Vol 13, No 2, March/April 2006 sicians are encouraged to inquire whether such certification is necessary in their state. To familiarize themselves with use of the C-arm, gynecologists can observe procedures performed by cardiologists, general surgeons, vascular surgeons, orthopaedic surgeons, or interventional radiologists.
Arteriotomy
Figure 1 The modern C-arm gives physicians the ability to retain the image of arterial anatomy.
mance of embolization and suggests different means of acquiring such skills.
Discussion of basic skills necessary The C-arm Understanding the C-arm is vital to performing any endovascular intervention. The angiography suite is a dedicated unit, with cost and construction requirements that will place it beyond the grasp of most gynecologists. Most gynecologists will learn and perform embolization procedures on a C-arm rather than a more expensive angiography unit. The C-arm offers many advantages over an angiography unit; these include cost and ability to move the unit from one room to another with ease. The modern C-arm (Figure 1) offers many features that are helpful to performance of embolization procedures. One of these features is the “road mapping” ability that allows the surgeon to retain the image of the arterial anatomy and use it literally as a map for placement of the glide wire and the catheter. Also, digital subtraction capability will be necessary to demonstrate the placement of the catheter into the correct artery and to confirm occlusion of the artery after embolization. Subtraction will also be helpful to demonstrate the continued flow to “nontarget” vessels after embolization and to search for ovarian blood supply to the myomatous uterus. The C-arm has features that allow the surgeon to better demonstrate the pelvic anatomy by rotating the image intensifier. Movement of the table up and down will change the appearance of the image. The amount of radiation used during embolization can be decreased by selecting the low-dose mode or the pulsemode. Operating surgeons in the room where interventional procedures are performed are responsible for safe use of radiation to the patient, operator, and other personnel. Many states require that the physician performing endovascular procedures be certified as a Fluoroscopy Supervisor. Phy-
Every interventional procedure begins with entry into the arterial system. The landmarks for entry into the femoral artery on the patient’s right side are obtained by palpating the femoral pulse and then placing a clamp at the level of the lower half of the greater trochanter head of the femur. By staying below this level, compression may be successfully applied at the end of the procedure without the risk of hematoma formation (Figure 2). Entry into the femoral artery follows techniques outlined by Seldinger.7 Most physicians enter the anterior portion of the femoral artery with an 18-gauge hollow needle. When return of arterial blood is seen, a glide wire is advanced. Most clinicians use the Bentson wire, which has a floppy end unlikely to dissect between the intimal layers of the artery. A scout film to confirm passage of the Bentson wire into the aorta is obtained. Next, most clinicians remove the needle and replace it with an introducing sheath large enough to accommodate the largest catheter that the physician anticipates using during the procedure. If the surgeon foresees the use of a 5.5F-diameter RIM catheter to cannulate the ipsilateral internal iliac artery, a 6F introducing sleeve would be the appropriate choice. The sheath has a port for irrigation during the procedure to prevent clot formation. Whatever solution is chosen for irrigation, 1000 units of heparin usually is added to this solution for each liter of fluid and placed
Figure 2 Image of a clamp placed at the lower half of the head of the femur.
McLucas
Endovascular skills
157
Figure 4 The SOFT-VU OMNI FLUSH catheter (AngioDynamics, Queensbury, NY) allows rapid diffusion of contrast through side holes.
Figure 3 Spectris Solaris EP MR Injection System (Medrad, Indianola, PA) enables rapid injection of radiopaque substance used in arteriogram.
under a blood pressure pump for continuous irrigation during the procedure.
Catheters vary in material, diameter, and shape of the distal tip. Here physician preference prevails; each surgeon will develop a preference for the catheter that works best for that individual. The diameters of catheters used in UAE are either 4F or 5F. The small diameters are useful for smaller uterine arteries, but are more likely to kink during the procedures. Interventionalists will advise to always lead with a guidewire. This decreases the chances of dissection during the procedure. The traditional guidewire used in the embolization procedure is a Terumo wire (Figure 5.) This wire is shaped in a curve at its end. To “steer” the Terumo into the proper vessel, a steering device is available. Steering a wire is a basic skill needed to perform cannulations of vessels.
Microcatheters Power injectors Physicians will want to obtain an arteriogram of the pelvic vessels before and after embolization. A hand injection will usually not be satisfactory to demonstrate the vascular anatomy in the aorta. Therefore, a power injector should be used (Figure 3), which will allow rapid injection under pressure of contrast.
Some physicians routinely use microcatheters that fit inside the 4F or 5F catheters to cannulate the uterine arter-
Catheter selection and use To the interventionalist, the choice of catheter is similar to the choice of instruments to a surgeon. Different catheters may be used for different phases of the procedure. Most physicians use more than one catheter during the embolization procedure. For example, the above mentioned power injector will work best with catheters with side holes to allow for a rapid diffusion of contrast (Figure 4), as opposed to a catheter with an opening in the end for passage of a glide wire.
Figure 5 A curved guidewire allows operator to “steer” the wire into smaller levels.
158
Journal of Minimally Invasive Gynecology, Vol 13, No 2, March/April 2006
Figure 6 Uterine artery supplying a myoma resembles appearance of hand grasping a baseball.
ies.8 Others use them only when the uterine artery is of a smaller diameter. Some physicians using microcatheters believe there is a less chance of arterial spasm. Those that don’t use microcatheters regularly will speak of the extended time necessary when using microcatheters and the inability to place larger particles through microcatheters. There will be times when use of microcatheters will be necessary, and all physicians seeking to perform endoscopic procedures in the pelvis should be familiar with microcatheters.
Pelvic arterial anatomy Every gynecologist has seen the uterine artery during the performance of an abdominal hysterectomy. However, many surgeons do not routinely operate upon arteries that branch into the uterine arteries. From the common iliac artery, the internal iliac artery arises. The uterine artery usually can be found in the anterior division of the internal iliac artery. The uterine artery courses from lateral to medial and the cephalad. The appearance of the uterine artery supplying a myoma is that of a hand grasping a baseball (Figure 6). The uterine artery’s appearance is like no other. Caution must be taken not to confuse the uterine artery with the vesicular artery supplying the bladder.
Figure 7
End-point of embolization.
under live fluoroscopy. The end-point of embolization (Figure 7) is nearing when particles flow more slowly while being injected and when reflux of particles is observed retrograde to the tip of the catheter. Another method for occluding the uterine artery is to use Gelfoam pledgelets (Pfizer, New York, NY) with particles or as a stand-alone method. Gelfoam is not a permanent particle but will occlude the artery for approximately 6 weeks. We have used Gelfoam for patients who wish to avoid premature menopause, which has been described with polyvinyl alcohol particles. Although we have only a few cases to compare, we are concerned about the higher incidence of myoma necrosis with Gelfoam. Thrombogenic coils may also have a role in UAE (Figure 8). Coils permanently block the artery but prevent access to the artery in future procedures. We have used coils along with very large particles in patients with very large uteri. Several of our early patients with large uteri required a hysterectomy for infection when large amounts of polyvinyl alcohol particles were used.11
Embolization The classic method of performing UAE is with polyvinyl alcohol particles.9 Spherical particles are also widely used for UAE. Because of their irregular shape and particle charge, polyvinyl alcohol particles tend to “clump” together and not reach the diameter of the arteriole corresponding to their outer diameter.10 Most interventionists start with 700-to 900-micron particles for one or two vials, and then move on to 900- to 1200-micron particles to complete the embolization. Particles are mixed with contrast and injected
Figure 8 supply.
Thrombogenic coils used to block arterial blood
McLucas
Endovascular skills
Figure 9
159
Simulators give gynecologists experience in catheter manipulation.
Acquisition of skills In any new surgical technology, there is a progression of learning. Students interested in learning endovascular procedures will initially study with a mentor. When a critical number of trained surgeons appears, centers of excellence throughout the country will emerge for such training. Next, fellowship experiences of several months will develop at such centers. In the future, endovascular skills will be taught in obstetrics and gynecology residency programs. The question of whether endovascular procedures will become a subspecialty of obstetrics and gynecology remains speculative. At this point, gynecologists wishing to acquire endovascular skills need to seek out mentors. Observation of interventional procedures is an excellent way to begin to understand the process of embolization. As the referring physician, the gynecologist should observe any patient undergoing UAE by an interventional radiologist and feel free to ask questions during the procedure. Because the procedure of embolization is the one the gynecologist will be learning, that is the ideal type to observe. However, he or she can also learn from observing cardiologists performing angioplasty and vascular surgeons placing stents in arteries. The next step in training, and the beginning of hands-on experience, should come with the use of simulators (Figure 9).12 These computer-assisted devices will give gynecologists experience in catheter manipulation. They can also be programmed to perform complications such as small vessels requiring a microcatheter to cannulate or how to manage an arterial dissection or perforation. Simulator training will take a student through a graduated series of exercises, allowing the physician to advance only after he or she has mastered the building skill level necessary to advance. Most simulator training centers will have a physician skilled in the performance of UAE on site to answer student questions during the training period. Simulator programs already exist for the placement of carotid stents and other vascular surgery procedures. We expect a program simulating UAE will be available in 2006. After many hours spent on simulator
training, physicians will want to spend time in an animal laboratory setting, perfecting their training in vivo. Because all surgeons advance at different paces, the amount of time spent in the laboratory and on simulators should be a matter of agreement between instructor and pupil. When that moment approaches, the student is ready to second assist in an interventional setting. The training that we have all received as surgeons followed such time-honored methods. Physicians assist until they are ready to assume primary responsibility for surgical procedures under the supervision of a trained interventionist.
Conclusion Acquisition of interventional skills will take time for gynecologists. We have not been trained in any of the necessary areas during our residencies. Given a commitment on the part of the gynecologist to devote a year of intensive study, the results will bear fruit. Most gynecologists should be able to maintain their regular practices while acquiring endovascular skills during this year. How much of the training period will be spent at the side of physicians performing UAE and how much of the time with simulators and in the animal laboratory will vary from setting to setting. Nonetheless, surgeons need to note that training in the technique of a procedure is only a small part of the learning curve. Judgment in when to perform the procedure will come with time.
References 1. McLucas B. Endovascular credentialing for obstetrician-gynecologists. Clin Obstet Gynecol. 2003;46:70 –75. 2. White RA, Fogarty TJ, Baker WH, et al. Endovascular surgery credentialing and training for vascular surgeons. J Vasc Surg. 1993;17: 1095–1102. 3. McLucas B, Adler L, Perrella R. Uterine fibroid embolization: nonsurgical treatment for symptomatic fibroids. J Am Coll Surg. 2001; 192:95–105.
160
Journal of Minimally Invasive Gynecology, Vol 13, No 2, March/April 2006
4. Tropeano G. The role of uterine artery embolization in the management of uterine fibroids. Curr Opin Obstet Gynecol. 2005;17:329 – 332. 5. Katsumori T, Akazawa K, Mihara T. Uterine artery embolization for pedunculated subserosal fibroids. AJR Am J Roentgenol. 2005;184: 399 – 402. 6. Clouse ME. The interventional radiologist: fellowship training. Cardiovasc Intervent Radiol. 1991;14:265–266. 7. Seldinger S. Catheter replacement of the needle in percutaneous arteriography (a new technique). Acta Radiologica. 1953;39:368 –376. 8. Goodwin SC, Vedantham S, McLucas B, Forno AE, Perrella R. Preliminary experience with uterine artery embolization for uterine fibroids. J Vasc Interv Radiol. 1997;8:517–526.
9. Pelage JP, Laurent A, Wassef M, et al. Uterine artery embolization in sheep: comparison of acute effects with polyvinyl alcohol particles and calibrated microspheres. Radiology. 2002;224:436 – 445. 10. Spies JB, Benenati J, Worthington-Kirsch R, Pelage JP. Initial experience with use of tris-acryl gelatin microspheres for uterine artery embolization for leiomyomata. J Vasc Intert Radiol. 2001;12:1059 – 1063. 11. Goodwin SC, McLucas B, Lee M, et al. Uterine artery embolization for the treatment of uterine leiomyomata: midterm results. J Vasc Intert Radiol. 1999;10:1159 –1165. 12. Dayal R, Faries PL, Lin SC, et al. Computer simulation as a component of catheter-based training. J Vasc Surg. 2004;40:1112– 1117.
Acquisition of endovascular skills for obstetriciangynecologists Bruce McLucas, MD From the Department of Obstetrics and Gynecology, University of California-Los Angeles, Los Angeles, California. KEYWORDS: Training; Endovascular; Embolization; Gynecology
Abstract STUDY OBJECTIVE: To identify skills not part of the training of obstetrician-gynecologists that are needed to perform endovascular procedures, especially uterine artery embolization. DESIGN: Literature review of known skills necessary to perform endovascular procedures. RESULTS: Important areas of endovascular skills are as follows. Understanding of the modern C-arm image intensifier is basic to performing endovascular procedures safely for the patient, physician, and others in the procedure room. Many states require physicians to obtain a Fluoroscopy Supervisors Permit when doing such interventions. Arteriotomy begins every endovascular procedure. Physicians must understand catheter manipulation and selection, and the use of microcatheters. An understanding of the pelvic arterial anatomy will help the surgeon identify the uterine arteries. Once in the uterine artery, the surgeon must understand how to successfully embolize the artery. As in any surgery, prevention of complications is important as well as management of complications once they arise. CONCLUSION: Obstetrician-gynecologists should plan on devoting a year for the acquisition of skills needed to perform endovascular procedures. Methods of acquiring such skills include simulator training, animal laboratory procedures, and observation of live procedures. Didactic courses will give physicians an overview of endovascular procedures. © 2006 AAGL. All rights reserved.
In order to be certified as confident to perform uterine artery embolization (UAE), physicians must, among other requirements, perform approximately 100 UAE procedures. Obtaining endovascular training is not exclusive to obstetrician-gynecologists. Many specialties have had to acquire skills in endovascular surgery, with cardiologists learning to perform angioplasty and vascular surgeons learning to place endovascular stents.1,2 Endovascular credentialing issues for obstetrician-gynecologists have been addressed in a previous paper.1 Many obstetrician-gynecologists have not had contact Corresponding author: Bruce McLucas, MD, 100 UCLA Medical Plaza, Suite 310, Los Angeles, CA 90024. E-mail: [email protected] Submitted August 25, 2005. Accepted for publication December 2, 2005.
1553-4650/$ -see front matter © 2006 AAGL. All rights reserved. doi:10.1016/j.jmig.2005.12.008
with interventional procedures or with the radiologists who perform them. Since the widespread success of UAE,3 many patients have requested this procedure to treat symptomatic myomata. Embolization is a reproducible technique offering a high rate of success4 in settings all over the world.5 Traditionally, UAE has been performed by interventional radiologists. These physicians finished a radiology residency and then took a 1-year fellowship to acquire their skills.6 Obstetrician-gynecologists offer their patients the possibility of continuity of care that radiologists cannot. At the current stage of development of endovascular procedures for obstetrician-gynecologists, physicians desiring to acquire skills will need to seek mentoring programs with qualified physicians already performing embolization. This paper seeks to outline the skills needed for the perfor-
156
Journal of Minimally Invasive Gynecology, Vol 13, No 2, March/April 2006 sicians are encouraged to inquire whether such certification is necessary in their state. To familiarize themselves with use of the C-arm, gynecologists can observe procedures performed by cardiologists, general surgeons, vascular surgeons, orthopaedic surgeons, or interventional radiologists.
Arteriotomy
Figure 1 The modern C-arm gives physicians the ability to retain the image of arterial anatomy.
mance of embolization and suggests different means of acquiring such skills.
Discussion of basic skills necessary The C-arm Understanding the C-arm is vital to performing any endovascular intervention. The angiography suite is a dedicated unit, with cost and construction requirements that will place it beyond the grasp of most gynecologists. Most gynecologists will learn and perform embolization procedures on a C-arm rather than a more expensive angiography unit. The C-arm offers many advantages over an angiography unit; these include cost and ability to move the unit from one room to another with ease. The modern C-arm (Figure 1) offers many features that are helpful to performance of embolization procedures. One of these features is the “road mapping” ability that allows the surgeon to retain the image of the arterial anatomy and use it literally as a map for placement of the glide wire and the catheter. Also, digital subtraction capability will be necessary to demonstrate the placement of the catheter into the correct artery and to confirm occlusion of the artery after embolization. Subtraction will also be helpful to demonstrate the continued flow to “nontarget” vessels after embolization and to search for ovarian blood supply to the myomatous uterus. The C-arm has features that allow the surgeon to better demonstrate the pelvic anatomy by rotating the image intensifier. Movement of the table up and down will change the appearance of the image. The amount of radiation used during embolization can be decreased by selecting the low-dose mode or the pulsemode. Operating surgeons in the room where interventional procedures are performed are responsible for safe use of radiation to the patient, operator, and other personnel. Many states require that the physician performing endovascular procedures be certified as a Fluoroscopy Supervisor. Phy-
Every interventional procedure begins with entry into the arterial system. The landmarks for entry into the femoral artery on the patient’s right side are obtained by palpating the femoral pulse and then placing a clamp at the level of the lower half of the greater trochanter head of the femur. By staying below this level, compression may be successfully applied at the end of the procedure without the risk of hematoma formation (Figure 2). Entry into the femoral artery follows techniques outlined by Seldinger.7 Most physicians enter the anterior portion of the femoral artery with an 18-gauge hollow needle. When return of arterial blood is seen, a glide wire is advanced. Most clinicians use the Bentson wire, which has a floppy end unlikely to dissect between the intimal layers of the artery. A scout film to confirm passage of the Bentson wire into the aorta is obtained. Next, most clinicians remove the needle and replace it with an introducing sheath large enough to accommodate the largest catheter that the physician anticipates using during the procedure. If the surgeon foresees the use of a 5.5F-diameter RIM catheter to cannulate the ipsilateral internal iliac artery, a 6F introducing sleeve would be the appropriate choice. The sheath has a port for irrigation during the procedure to prevent clot formation. Whatever solution is chosen for irrigation, 1000 units of heparin usually is added to this solution for each liter of fluid and placed
Figure 2 Image of a clamp placed at the lower half of the head of the femur.
McLucas
Endovascular skills
157
Figure 4 The SOFT-VU OMNI FLUSH catheter (AngioDynamics, Queensbury, NY) allows rapid diffusion of contrast through side holes.
Figure 3 Spectris Solaris EP MR Injection System (Medrad, Indianola, PA) enables rapid injection of radiopaque substance used in arteriogram.
under a blood pressure pump for continuous irrigation during the procedure.
Catheters vary in material, diameter, and shape of the distal tip. Here physician preference prevails; each surgeon will develop a preference for the catheter that works best for that individual. The diameters of catheters used in UAE are either 4F or 5F. The small diameters are useful for smaller uterine arteries, but are more likely to kink during the procedures. Interventionalists will advise to always lead with a guidewire. This decreases the chances of dissection during the procedure. The traditional guidewire used in the embolization procedure is a Terumo wire (Figure 5.) This wire is shaped in a curve at its end. To “steer” the Terumo into the proper vessel, a steering device is available. Steering a wire is a basic skill needed to perform cannulations of vessels.
Microcatheters Power injectors Physicians will want to obtain an arteriogram of the pelvic vessels before and after embolization. A hand injection will usually not be satisfactory to demonstrate the vascular anatomy in the aorta. Therefore, a power injector should be used (Figure 3), which will allow rapid injection under pressure of contrast.
Some physicians routinely use microcatheters that fit inside the 4F or 5F catheters to cannulate the uterine arter-
Catheter selection and use To the interventionalist, the choice of catheter is similar to the choice of instruments to a surgeon. Different catheters may be used for different phases of the procedure. Most physicians use more than one catheter during the embolization procedure. For example, the above mentioned power injector will work best with catheters with side holes to allow for a rapid diffusion of contrast (Figure 4), as opposed to a catheter with an opening in the end for passage of a glide wire.
Figure 5 A curved guidewire allows operator to “steer” the wire into smaller levels.
158
Journal of Minimally Invasive Gynecology, Vol 13, No 2, March/April 2006
Figure 6 Uterine artery supplying a myoma resembles appearance of hand grasping a baseball.
ies.8 Others use them only when the uterine artery is of a smaller diameter. Some physicians using microcatheters believe there is a less chance of arterial spasm. Those that don’t use microcatheters regularly will speak of the extended time necessary when using microcatheters and the inability to place larger particles through microcatheters. There will be times when use of microcatheters will be necessary, and all physicians seeking to perform endoscopic procedures in the pelvis should be familiar with microcatheters.
Pelvic arterial anatomy Every gynecologist has seen the uterine artery during the performance of an abdominal hysterectomy. However, many surgeons do not routinely operate upon arteries that branch into the uterine arteries. From the common iliac artery, the internal iliac artery arises. The uterine artery usually can be found in the anterior division of the internal iliac artery. The uterine artery courses from lateral to medial and the cephalad. The appearance of the uterine artery supplying a myoma is that of a hand grasping a baseball (Figure 6). The uterine artery’s appearance is like no other. Caution must be taken not to confuse the uterine artery with the vesicular artery supplying the bladder.
Figure 7
End-point of embolization.
under live fluoroscopy. The end-point of embolization (Figure 7) is nearing when particles flow more slowly while being injected and when reflux of particles is observed retrograde to the tip of the catheter. Another method for occluding the uterine artery is to use Gelfoam pledgelets (Pfizer, New York, NY) with particles or as a stand-alone method. Gelfoam is not a permanent particle but will occlude the artery for approximately 6 weeks. We have used Gelfoam for patients who wish to avoid premature menopause, which has been described with polyvinyl alcohol particles. Although we have only a few cases to compare, we are concerned about the higher incidence of myoma necrosis with Gelfoam. Thrombogenic coils may also have a role in UAE (Figure 8). Coils permanently block the artery but prevent access to the artery in future procedures. We have used coils along with very large particles in patients with very large uteri. Several of our early patients with large uteri required a hysterectomy for infection when large amounts of polyvinyl alcohol particles were used.11
Embolization The classic method of performing UAE is with polyvinyl alcohol particles.9 Spherical particles are also widely used for UAE. Because of their irregular shape and particle charge, polyvinyl alcohol particles tend to “clump” together and not reach the diameter of the arteriole corresponding to their outer diameter.10 Most interventionists start with 700-to 900-micron particles for one or two vials, and then move on to 900- to 1200-micron particles to complete the embolization. Particles are mixed with contrast and injected
Figure 8 supply.
Thrombogenic coils used to block arterial blood
McLucas
Endovascular skills
Figure 9
159
Simulators give gynecologists experience in catheter manipulation.
Acquisition of skills In any new surgical technology, there is a progression of learning. Students interested in learning endovascular procedures will initially study with a mentor. When a critical number of trained surgeons appears, centers of excellence throughout the country will emerge for such training. Next, fellowship experiences of several months will develop at such centers. In the future, endovascular skills will be taught in obstetrics and gynecology residency programs. The question of whether endovascular procedures will become a subspecialty of obstetrics and gynecology remains speculative. At this point, gynecologists wishing to acquire endovascular skills need to seek out mentors. Observation of interventional procedures is an excellent way to begin to understand the process of embolization. As the referring physician, the gynecologist should observe any patient undergoing UAE by an interventional radiologist and feel free to ask questions during the procedure. Because the procedure of embolization is the one the gynecologist will be learning, that is the ideal type to observe. However, he or she can also learn from observing cardiologists performing angioplasty and vascular surgeons placing stents in arteries. The next step in training, and the beginning of hands-on experience, should come with the use of simulators (Figure 9).12 These computer-assisted devices will give gynecologists experience in catheter manipulation. They can also be programmed to perform complications such as small vessels requiring a microcatheter to cannulate or how to manage an arterial dissection or perforation. Simulator training will take a student through a graduated series of exercises, allowing the physician to advance only after he or she has mastered the building skill level necessary to advance. Most simulator training centers will have a physician skilled in the performance of UAE on site to answer student questions during the training period. Simulator programs already exist for the placement of carotid stents and other vascular surgery procedures. We expect a program simulating UAE will be available in 2006. After many hours spent on simulator
training, physicians will want to spend time in an animal laboratory setting, perfecting their training in vivo. Because all surgeons advance at different paces, the amount of time spent in the laboratory and on simulators should be a matter of agreement between instructor and pupil. When that moment approaches, the student is ready to second assist in an interventional setting. The training that we have all received as surgeons followed such time-honored methods. Physicians assist until they are ready to assume primary responsibility for surgical procedures under the supervision of a trained interventionist.
Conclusion Acquisition of interventional skills will take time for gynecologists. We have not been trained in any of the necessary areas during our residencies. Given a commitment on the part of the gynecologist to devote a year of intensive study, the results will bear fruit. Most gynecologists should be able to maintain their regular practices while acquiring endovascular skills during this year. How much of the training period will be spent at the side of physicians performing UAE and how much of the time with simulators and in the animal laboratory will vary from setting to setting. Nonetheless, surgeons need to note that training in the technique of a procedure is only a small part of the learning curve. Judgment in when to perform the procedure will come with time.
References 1. McLucas B. Endovascular credentialing for obstetrician-gynecologists. Clin Obstet Gynecol. 2003;46:70 –75. 2. White RA, Fogarty TJ, Baker WH, et al. Endovascular surgery credentialing and training for vascular surgeons. J Vasc Surg. 1993;17: 1095–1102. 3. McLucas B, Adler L, Perrella R. Uterine fibroid embolization: nonsurgical treatment for symptomatic fibroids. J Am Coll Surg. 2001; 192:95–105.
160
Journal of Minimally Invasive Gynecology, Vol 13, No 2, March/April 2006
4. Tropeano G. The role of uterine artery embolization in the management of uterine fibroids. Curr Opin Obstet Gynecol. 2005;17:329 – 332. 5. Katsumori T, Akazawa K, Mihara T. Uterine artery embolization for pedunculated subserosal fibroids. AJR Am J Roentgenol. 2005;184: 399 – 402. 6. Clouse ME. The interventional radiologist: fellowship training. Cardiovasc Intervent Radiol. 1991;14:265–266. 7. Seldinger S. Catheter replacement of the needle in percutaneous arteriography (a new technique). Acta Radiologica. 1953;39:368 –376. 8. Goodwin SC, Vedantham S, McLucas B, Forno AE, Perrella R. Preliminary experience with uterine artery embolization for uterine fibroids. J Vasc Interv Radiol. 1997;8:517–526.
9. Pelage JP, Laurent A, Wassef M, et al. Uterine artery embolization in sheep: comparison of acute effects with polyvinyl alcohol particles and calibrated microspheres. Radiology. 2002;224:436 – 445. 10. Spies JB, Benenati J, Worthington-Kirsch R, Pelage JP. Initial experience with use of tris-acryl gelatin microspheres for uterine artery embolization for leiomyomata. J Vasc Intert Radiol. 2001;12:1059 – 1063. 11. Goodwin SC, McLucas B, Lee M, et al. Uterine artery embolization for the treatment of uterine leiomyomata: midterm results. J Vasc Intert Radiol. 1999;10:1159 –1165. 12. Dayal R, Faries PL, Lin SC, et al. Computer simulation as a component of catheter-based training. J Vasc Surg. 2004;40:1112– 1117.