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Background Dynamic compliance (Cd) of the adult thoracic ascending and arch aorta has had limited in vivo evaluation in patients with aortic disease. This study evaluates aortic compliance using intravascular ultrasound (IVUS) across a range of thoracic aortic diseases. Methods Seventy-nine patients undergoing thoracic aortic endovascular procedures had Cd measurements of the ascending aorta proximal to the origin of the brachiocephalic trunk and distal to the origin of the left common carotid artery using IVUS before endograft deployment. Cd was calculated for each segment using the following equation, Cd = ΔD/(D • ΔP) where ΔD = change in aortic diameter, D = diameter in diastole, and ΔP = pulse pressure. Results Mean Cd of the ascending aorta in all patients (18.4%/mm Hg) and aortic arch (16.5 %/100 mm Hg) did not differ significantly. Compliance was significantly lower in patients being treated for thoracic aortic aneurysm and penetrating ulcer than in patients with traumatic rupture, acute and chronic dissection (P = 0.009). Compliance was significantly higher in patients with aortic transection compared with thoracic aneurysm or penetrating ulcer (P = 0.001). Compliance decreased with age by 0.44 ± 0.06 (P = 0.001) per year in the ascending aorta and 0.41 ± 0.05 (P = 0.001) per year in the aortic arch. Compliance did not increase with diameter when adjusted for age (P = 0.65). Compliance measured in the ascending aorta in 7 patients after descending thoracic aortic endograft repair decreased to 12.6%/100 mm Hg, although not significant (P = 0.18). Conclusions Ascending and aortic arch compliance is significantly higher than reported for peripheral vessels. Thoracic aortic compliance decreases with age and is not related to aortic diameter. The results of the present study are important when considering the development of endoprosthesis devices and long-term effects on the thoracic aorta.

There is no sensitive tool to monitor embolic events and predict patients at a risk for strokes during thoracic endovascular aortic repair. We examined the relationship between the number of high intensity transient signals (HITS) by transcranial doppler ultrasound and the extent of atherosclerotic plaques in aortic arch. Thirteen patients were treated as a part of a single center United States Food and Drug Administration-approved investigational device exemption for various thoracic aortic pathologies. Bilateral transcranial doppler ultrasound transducers recorded the number of HITS. CT angiography and intravascular ultrasound were used to measure the thickness of mural thrombi and determine their arch location. All 13 patients had detectable HITS, and one patient sustained a stroke. Eleven patients had quantifiable mural thrombi. The highest HITS were observed in patients with thrombi in zones 2 to 3. All three patients with bovine arch had more HITS in the right middle cerebral artery whereas the patients with normal arch anatomy had more HITS in the left middle cerebral artery. The presence of mural thrombi in zones 2 and 3, irrespective of their thickness, was associated with increased HITS during thoracic endovascular aortic repair. This is the first study to characterize the significance of mural thrombi in aortic arch and their relationship to embolic events during aortic arch manipulations.

Objective Structural changes within the aorta after thoracic endovascular aortic repair (TEVAR) for acute complicated type B thoracic aortic dissections (ABAD) remain unknown. This study reviewed and analyzed morphologic changes, volumetric data, and clinical outcomes of patients with ABAD. Methods Forty-one consecutive patients with ABAD, all with the volumetric analysis of aortic luminal changes and ≥1 year of follow-up, were treated as a part of a single-center U.S. Food and Drug Administration (FDA)-approved investigational device exemption (IDE) trial from 2002 to 2009. Indications were malperfusion in 17, rupture in 12, chest pain in 6, acute enlargement in 4, and uncontrolled hypertension in 2. Duration of symptoms was ≤14 days. Three-dimensional M2S computed tomography reconstructions (Medical MetRx Solutions, West Lebanon, NH) were analyzed for aortic volume and diameter changes, regression of the false lumen, and expansion of the true lumen. Results Emergent surgery was required in 17 (42%) patients, excluding one death at induction. Procedural success rate was 92.5%. The 30-day mortality was 4.9% for malperfusion, 4.9% for rupture, and 0% for all others, with late mortality of 0%, 9.8%, and 7.3%, respectively. Mean follow-up was 12.4 months. Permanent stroke and paraplegia rates were 4.9% (n = 2) and 0%. Ten of 12 secondary interventions were performed for 6 proximal endoleaks, 1 distal cuff endoleak, and 3 distal reperfusions. For the 33 patients without endoleaks, the true lumen volume increased by 29% at 1 month, 51% at 1 year, and 80% at 5 years. Volume regression of the false lumen was 69%, 76%, and 86%, respectively. The true lumen volume did not change at 1 month or 1 year in the endoleak group (n = 7) but increased 50% at 2 years after secondary intervention. A 10% reduction of abdominal aortic volume distal to endograft occurred over 5 years in the absence of endoleaks. Conclusions TEVAR offers a promising solution to patients with ABAD. Aortic morphologic changes occur shortly after TEVAR and remain predictable up to 5 years with continuous expansion of the true lumen and regression of the false lumen. A lack of increase in the true lumen volume is associated with endoleaks or distal reperfusion.

La adenosina se ha utilizado para inducir la asistolia y permitir el despliegue de los implantes endoluminales. Sin embargo, no se ha descrito la aplicacion de dosis altas de adenosina en pacientes conscientes. En este estudio prospectivo, administramos dosis altas de adenosina en pacientes sometidos a colocacion de una endoprotesis toracica. Se investigo la duracion de la asistolia en relacion con la dosis de adenosina, la seguridad y el perfil de efectos secundarios. Todos los pacientes en los que se coloco una endoprotesis toracica entre 1998 y 2006 fueron los sujetos potenciales del estudio. Fueron sometidos a cuidados anestesicos monitorizados (CAM) y a anestesia local, a menos que estuviese contraindicado. La adenosina se administro en bolo intravenoso rapido de 36 mg inmediatamente antes de desplegar la endoprotesis. Cuando fue necesario, se administro una segunda dosis de 18 mg. Se registro la duracion de la asistolia asi como los signos vitales del paciente antes y despues de la administracion. Se obtuvo el perfil de los efectos secundarios intra y postoperatorios. Se administro adenosina a un total de 46 pacientes (34 hombres, 12 mujeres). La media de edad fue de 60,4 ± 17,5 anos. La puntuacion segun la American Society of Anesthesiologists fue de II en un paciente (2%), III en 6 (13%), y IV en 39 (85%). Dieciocho pacientes recibieron una dosis unica de 36 mg de adenosina, en 15 se administro una segunda dosis de 18 mg, y en 13 una dosis no estandar. La duracion de la asistolia fue de 18,8 ± 8,8 y 11,6 ± 5,5 s para la dosis de 36 y 18 mg, respectivamente. Se logro el exito tecnico en todos los casos. Las diferencias fueron estadisticamente significativas (p = 0,0009). No se produjeron complicaciones cardiacas o pulmonares graves. Pueden administrarse dosis altas de adenosina de forma segura en pacientes conscientes. La respuesta fue predecible y reproducible. Las dosis utilizadas en nuestro estudio inducen una asistolia de duracion suficiente, lo que aseguro el despliegue preciso de las endoprotesis toracicas.

L'adenosine a ete utilisee pour entrainer une asystolie et aider au deploiement des endoprotheses. Cependant, l'application de fortes doses d'adenosine chez des malades conscients n'a pas ete decrite. Dans cette etude prospective, nous avons administre de l'adenosine a hautes doses chez des malades ayant la mise en place d'endoprotheses thoraciques. Nous avons etudie la duree de l'asystolie en relation avec la dose d'adenosine, sa surete et les effets secondaires. Tous les malades ayant eu une endoprothese thoracique entre 1998 et 2006 ont ete les sujets d'etudes potentiels. Ils ont eu un monitorage par des anesthesistes et une anesthesie locale sauf contre-indication. L'adenosine a ete administree par un bolus intra-veineux immediatement avant le deploiement de l'endoprothese. Chaque malade a eu une dose de 36 mg. Si necessaire, une seconde dose de 18 mg a ete administree. La duree de l'asystolie a ete enregistree apres chaque administration. Les signes vitaux avant et apres l'administration ont egalement ete documentes. Les effets secondaires ont ete notes en per et en post-operatoire. Un total de 46 malades ont eu de l'adenosine (34 hommes, 12 femmes). L'âge moyen etait de 60,4 ± 17,5 ans. Les scores de l'American Society of Anesthesiologist etaient II chez un malade (2%), III chez 6 malades (13%) et IV chez 39 malades (85%). Dix-huit malades ont eu une dose unique de 36 mg d'adenosine, 15 ont eu une seconde dose de 18 mg et 13 ont eu des doses non standardisees. Les durees d'asystolie ont ete de 18,8 ± 8,8 et de 11,6 ± 5,5 secondes respectivement pour les doses de 36 et 18 mg. Le succes technique a ete obtenu dans tous les cas. Les differences etaient statistiquement significatives (p = 0,0009). Il n'y a pas eu de complication cardiaque ou pulmonaire grave. L'adenosine a haute dose peut etre administree en toute securite chez des malades conscients. La reponse en fonction de la dose etait previsible et reproductible. Les doses utilisees dans notre etude permettent une duree suffisante d'asystolie, qui a permis un deploiement precis des endoprotheses thoraciques.

Endoluminal repair of abdominal aortic aneurysms (AAA) is associated with decreased blood loss and transfusion requirements when compared to open AAA repair. We evaluated the use of an intraoperative autotransfusion system during endoluminal exclusion of AAAs. Fifty endoluminal AAA procedures selected at random were reviewed retrospectively. Patients were divided into 4 groups according to their estimated blood loss: Group I, 20 patients (0–500 cc); Group II, 18 patients (501–1,000 cc); Group III, 7 patients (1,001–1,500 cc); and Group IV, 5 patients (1,501–3,400 cc). The average blood loss was 327 cc for Group I, 728 cc for Group II, 1,217 for Group III, and 2,125, for Group IV. The overall blood loss was 834 cc, but 75 per cent was recovered. Hematuria was always present when greater than 1,000 cc of blood was retransfused, but renal function was not affected even with the concomitant administration of radiographic contrast. Only one patient required an autologous blood transfusion. The use of an autotransfusion device is safe, efficacious, and appears to further limit the need for homologous blood transfusion in patients undergoing endoluminal AAA repair.

Purpose: To evaluate the outcome of aortic endografts deployed in large infrarenal necks and to identify any association of preoperative aneurysm characteristics and postoperative morphological changes with the incidence of neck dilatation and device migration in this patient subset. Methods: The records of 47 patients (41 men; mean age 74, range 55–84) with large aortic neck diameters treated with Talent stent-grafts from 1998 to 2001 were reviewed. Patients with anatomical criteria that precluded aneurysm exclusion with currently available devices were preferentially selected. Mean baseline aneurysm morphology included 27.6-mm (range 18–33.4) suprarenal and 28.1-mm (range 24–34) infrarenal neck diameters; the infrarenal neck length was 26 ± 16 mm with angulation of 37° ± 18°. Computed tomographic (CT) angiograms up to 3 years were analyzed using specialized interactive software; migration was defined as >1-cm change in the distance from the lower renal artery to the top of the device. Pre- and postoperative morphological characteristics of the aneurysm were compared between patients with and without migration. Results: Of the 45 patients successfully treated, 40 had complete CT data for analysis. During a mean 17-month follow-up, 7 (17.5%) of the 40 devices exhibited distal migration. Six patients required secondary procedures; 5 were in the migration cohort. No preoperative anatomical characteristic or degree of neck dilatation over time was predictive of stent-graft migration. Aneurysm sac regression was significant at 1 (–0.09 ± 4.90 mm) and 2 (–1.48 ± 2.56 mm) years in endografts without migration (p1 cm predicted the need for secondary interventions (pConclusions: Endovascular repair is successful in patients with large infrarenal necks and complex neck morphology. Changes in aneurysm remodeling over time were similar to reported observations in patients with more favorable neck criteria. Although no anatomical factor associated with migration could be identified from this analysis, distal displacement >1 cm correlated with the need for a secondary intervention.

To assess the fatigue and in vivo performance of a new stent-graft incorporating bovine peritoneum lining that is designed for application in peripheral vascular occlusive disease.Bovine peritoneum-lined stent-grafts were subjected to accelerated in vitro pulsatile fatigue and axial/torsional fatigue testing designed to simulate 10 years of physiological strain on the devices. At specified times the devices were evaluated for stent fracture, suture failure, or tissue tearing. Seven dogs underwent bilateral common iliac artery (CIA) balloon angioplasty injury with unilateral placement of the peritoneum-lined stent-graft. Angiography and intravascular ultrasound were performed prior to treatment, after treatment, and prior to sacrifice at 30 days. Vessels were perfusion fixed and histologically evaluated at 5 regions: above stent, proximal stent, mid stent, distal stent, and below stent.No evidence of stent, suture, or tissue failure was present during or after pulsatile and axial/torsional fatigue testing. At 30±0.3 days after implantation, all vessels were patent. The average lumen area at explantation across stented vessels was 25.45 mm(2). Lumen areas tended to be reduced above (23.57 mm(2)) and below (24.17 mm(2)) the stent. Lumen areas were consistent across stented regions at explantation (proximal stent 27.80 mm(2), mid stent 25.88 mm(2), and distal stent 25.81 mm(2)). The mean neointimal area in peritoneum-lined stents was 2.02±1.52 mm(2), with a neointima:media ratio of 1.03±0.50. These values were significantly lower in the above and below stent areas than in the stented regions, but there was no difference in either measure within the proximal, mid, or distal stent.The custom-designed peritoneum-lined stent-graft is promising for clinical peripheral applications due to its ability to resist relevant long-term physiological stresses and outstanding short-term patency rates in canine implantations.

Purpose: To report early clinical experiences with color 3-dimensional intravascular ultrasound (3-D IVUS) in assisting peripheral interventions. Technique: A 3.5-F, 20-MHz IVUS catheter that utilizes ChromaFlo computer software to demonstrate blood flow in color was evaluated in over 100 peripheral interventions. ChromaFlo captures up to 30 conventional IVUS frames every second and generates “realtime” imaging. The software compares sequential axial IVUS images and interprets any differences in the position of echogenic blood particles, which are displayed as colorized flow in axial or 3-D renderings. Conclusions: ChromaFlo-enhanced IVUS demonstrates colorized blood flow inside the vessel lumen, which is helpful in distinguishing echolucent disease from luminal blood flow and can also be used to perform peripheral interventions in patients with renal failure or allergy, avoiding the use of contrast media.

Purpose: To evaluate the healing response of normal canine arteries to a self-expanding nitinol stent encapsulated in carbon-lined expanded polytetrafluoroethylene (ePTFE). Methods: Twenty-eight dogs were divided into aortic (n = 18) or iliac (n = 10) groups. In the latter, 2 animals were assigned to implantation intervals of 7, 30, and 90 days, respectively; 4 were designated for 180-day implantation. Half of the animals in each subgroup received a second overlapping stent-graft in one iliac artery. In the aortic cohort, 6 animals were assigned to the 180-day implantation group (2 with dual devices) and 3 to each of the others (1 dual implantation in each group). The devices were evaluated with angiography and intravascular ultrasound at implantation and explantation. After harvesting and gross examination, the specimens were examined microscopically and with scanning electron microscopy. Results: The 49 implanted devices (24 aortic and 25 common iliac) were all widely patent at explantation, save for 2 iliac stents that had moderate (Conclusions: The carbon-lined ePTFE-encapsulated stent is a novel approach to arterial stenting. The progressive endothelialization and lack of inflammatory reaction may provide improved long-term patency. Further study of this stent-graft design is warranted.

Objective: The objective of this study was to analyze a single-center experience in which descending thoracic aortic aneurysms (TAAs) were treated with a new self-expanding endovascular prosthesis (Medtronic AVE). Methods: Twenty-six patients (13 men, 13 women) with American Society of Anesthesiology grades II to IV and ages ranging from 53 to 92 years (average, 74 years) consented as part of a Phase I Food and Drug Administration–approved trial. Treated lesions included TAAs that were 5 to 10 cm in diameter, 12 diffuse dilations or fusiform aneurysms, and four saccular aneurysms. There were also nine chronic dissections (2 aneurysmal dilations and 7 symptomatic acute recurrent dissections). Three patients (2 with diffuse/fusiform and 1 with dissection) presented with hemothorax, contrast extravasation, or both. Results: Twenty-five of the 26 patients who consented (96% technical success) were treated successfully with no surgical conversions. Eighteen patients have been followed up from 1 to 22 months (average, 9 months). One patient is lost to follow-up, and six patients have died (24%). One procedure-related death (4%) occurred within the 30-day postoperative period and was caused by diffuse embolization. There were no device-related deaths. Five additional patients (20%) have died during the study of comorbid conditions. Complications included one massive myocardial infarction 24 hours after the procedure requiring balloon counterpulsation and long-term dialysis, one cardiac tamponade resulting from central line placement before the procedure, one progression of aneurysm dilation proximal to the device at 1 year, and one bilateral lower extremity paralysis occurring 12 hours after successful deployment. Seven patients (5 women) had femoral artery reconstructions or iliac artery grafts to repair injuries during deployment catheter passage. Other significant parameters included average procedure time (2 hours 40 minutes; range, 1 hour 30 minutes to 5 hours 30 minutes), 450 cc average blood loss (n = 25; 100-3000 cc) being replaced by means of autotransfusion with only two patients receiving banked blood products, and an average 2 days to resumption of normal diet, 1 day in the intensive care unit, and 5 days' hospitalization postprocedure in uncomplicated cases (n = 22). One patient had an endoleak immediately after the procedure that sealed without treatment. Follow-up of all patients ranging from 1 to 22 months (average, 9 months; n=18) demonstrates continued exclusion of the aneurysm with no endoleaks and either stable or decreasing aneurysm volume, except in one patient with volume increase and no obvious etiology who continues to be investigated. Conclusions: The study suggests that endovascular prosthesis exclusion of TAAs with an AneuRx self-expanding tubular device may be effective in many patients who are at significant risk for open surgical repair and substantiates further clinical investigation to confirm these findings.(J Vasc Surg 2001;33:927-34.)

A preliminary single-animal study of in vivo argon laser vascular welding was conducted using a canine model. The effects of temperature feedback control and saline drip cooling on patency and collagen cross-linking were investigated. The surface temperature at the centre of the laser spot was monitored using a two-colour infrared thermometer. The surface temperature was limited by either a saline drip or feedback control of the laser. Acute patency was evaluated and collagen cross-link assays were performed. Though both protocols yielded successful tissue fusion, welds maintained at a surface temperature of 50°C using feedback control had an elevated cross-link count compared to controls, whereas tissues irradiated without feedback control experienced a cross-link decrease. Simulations using the LATIS (LAser-TISsue) computer code suggest that drip-cooled procedures achieve significantly higher temperatures beneath the tissue surface than temperature feedback-controlled procedures. Differences between the volumetric heating associated with drip-cooled and feedback-controlled protocols may account for the different effects on collagen cross-links. Covalent mechanisms may play a role in argon laser vascular fusion.

Purpose: To quantify the error introduced by noncoaxial intravascular ultrasound (IVUS) imaging and to evaluate the use of a balloon-tipped catheter in compensating for intraluminal angulation and subsequent dimensional inaccuracy. Methods: The effect of noncoaxial IVUS imaging was investigated in both a polyvinyl chloride phantom and an in vitro canine aorta using a calibrated setup to measure angulation off axis. Imaging was performed at increasing angulation (creating an elliptical image) in both phantoms, with the transducer centered and off center. Diameters were compared to the original coaxial diameter, as well as calculated diameters based on specific angles off axis. The percentage change (error) was also calculated at these angles. The measurements were repeated using a balloon-tipped catheter to center the transducer. Results: The measured diameters and percentage changes compared closely with their calculated counterpart. Up to 25° off axis, the apparent increase in diameter measurement was nearly 10%. Angulation from 30° to 70° resulted in an increase of 15% to 192%. Use of the centering balloon reduced the amount of error by 70% to 85% but was limited to angles ≤ 25° due to the design of the test apparatus. Conclusions: The error introduced by noncoaxial IVUS imaging can be significant and may be partially corrected by the use of a centering balloon. Further studies in the clinical application of a centering device are warranted.

Purpose:To describe the endovascular treatment of a gunshot injury to the visceral aorta and the role of various imaging modalities in the staging and planning of the endograft procedure.Methods and Results:The bullet entered the aorta posteriorly beneath the origin of the superior mesenteric artery and traversed the wall in a tangential manner entering the lumen proximal to the renal arteries. Intravascular ultrasound (IVUS) imaging and spiral computed tomography (CT) identified the injury that the initial angiograms failed to demonstrate. Combined use of IVUS and CT imaging enabled observation of the evolution of a pseudoaneurysm until an interval when endograft exclusion was possible. A stent-graft was customized based on precise IVUS and CT dimensional data and implanted successfully through an arteriotomy in the common femoral artery 3 weeks after the initial injury. Three-month follow-up imaging demonstrated continued exclusion of the pseudoaneurysm, and the patient remains well at 16 months.Conclus...

Intravascular ultrasound (IVUS) imaging is a relatively new, rapidly evolving technology that enables precise catheter-based assessment of the dimensions and morphology of vascular structures and lesions. In extensive preclinical laboratory developmental studies and in clinical cases of endograft deployment for treatment of abdominal aortic aneurysms, we have found IVUS invaluable for determining key parameters of aortic morphology before and during interventions and for assessing the accuracy of deployment after device placement. By combining the IVUS data with information obtained from angiography, magnetic resonance imaging, and computed tomography (axial and three-dimensional reconstructions), we have been able to size devices and choose optimal fixation sites to prevent endoleaks and maintain luminal patency acutely and in the long term.

Purpose: To describe a case of endoluminal graft exclusion of a proximal para-anastomotic pseudoaneurysm that occurred 17 years following aortobifemoral bypass for occlusive disease. Methods and Results: The lesion was found on abdominal ultrasound examination as part of a work-up for acute abdominal pain and upper gastrointestinal bleeding in a 67-year-old male. A 5-cm saccular pseudoaneurysm was confirmed by preintervention aortography and spiral computed tomography (CT) scanning. Because of the patient's acute symptoms and high-risk medical condition (cardiomyopathy), he was deemed a candidate for endoluminal bypass. At the time of intervention, intravascular ultrasound (IVUS) interrogation identified a 3.5-cm-long separation of the existing aortic graft from the proximal aortic stump with a large pseudoaneurysm. The lesion was isolated and repaired by placement of an aortic-to-right iliac endoluminal bypass, ligation of the left limb of the aortofemoral graft, and femorofemoral bypass to restore blood flow to the lower extremities. Spiral CT scans at 48 hours and 3 months following the procedure confirmed complete isolation of the lesion. Conclusions: This case illustrates the feasibility of endografting for repair of aortic para-anastomotic pseudoaneurysms, and it also highlights the potential role of IVUS imaging in endoluminal graft deployment.

Purpose: The study evaluated the deployment and healing of a novel self-expanding modular bifurcation endovascular prosthesis in a canine abdominal aortic aneurysm model. The endoluminal prosthesis consists of self-expanding nitinol stents lined by a synthetic prosthesis. One component of the device is a bifurcated body with a 12- to 14-mm diameter aortic segment and an integral 7- to 8-mm diameter iliac limb. The bifurcated body also has a stent-reinforced opening (pant-leg) for subsequent insertion of a contralateral 7- to 8-mm diameter iliac limb component. Methods: Seventeen bifurcated prosthesis were placed; 7 were inserted through the left common carotid artery and 10 from the femoral arteries. With either route of access the 16F or 17F aortoiliac limb and the 13F iliac limb delivery catheters enabled easy passage and secure positioning of the bifurcated prostheses. Predeployment and postdeployment inspection of the dimensions and continuity of the aotoiliac prosthetic components were evaluated by cinefluoroscopy and intravascular ultrasonography (IVUS). Results: After deployment was done, interval patency was assessed with angiography, IVUS, and contrast-enhanced computed tomography with the prostheses removed for analysis at 1 week (n = 4), 1 month (n = 3), 3 months (n = 4), and 6 months (n = 6). Five of the first seven implanted prostheses had occlusion of segments of the device. In two dogs the bifurcated body and both legs were occluded. In the other three the nonoccluded leg and bifurcation body were fully patent. In the first seven animals IVUS at implantation showed compression of an iliac leg by the orifice of the contralateral iliac component. After concentric fixation of the flow divider was performed, only one additional iliac limb occlusion occurred in the next 10 animals. Cinefluoroscopy, computed tomography, IVUS imaging, and histologic analysis of retrieved specimens demonstrated healing of the aortoiliac prostheses without evidence of perigraft leaks. Conclusions: This feasibility study demonstrates the ability to deploy and maintain acceptable patency of a self-expanding endoluminal, modular bifurcation prosthesis in a canine aortic model. Clinical evaluation of the device is planned for the near future. (J Vasc Surg 1996;24;1034-42.)

Purpose: This report reviews our preliminary experience of prospective treatment of arterial lesions with endoluminal grafts in a Food and Drug Administration (FDA) approved, investigator-sponsored Investigation Device Exemptions study. The utility and accuracy of various imaging methods, including angiography, cinefluoroscopy, computed tomography (CT), intravascular ultrasonography (IVUS), and duplex scanning, in performing the procedures was also assessed. Methods: Thirty-one patients were evaluated; 17 patients were treated, including 11 with abdominal aortic aneurysms, one with an aortic occlusive lesion, two with iliac artery aneurysms, and three with traumatic arteriovenous fistulas. Twelve of the 14 patients who had aorta and iliac artery lesions were high-risk. The mean follow-up of patients treated was 9 months (range, 6 to 15 months). Results: Aortoaortic endoluminal interposition procedures were not successful for treating abdominal aortic aneurysms early in the study (n = 3). Aortoiliac endoluminal bypass, contralateral iliac artery occlusion, and femorofemoral bypass procedures were successful in seven of eight subsequent cases (88%), with no incidence of endoleaks at either the proximal or distal fixation sites using the deployment methods described in this report. The 30-day operative mortality rate on follow-up evaluations for patients who underwent aortoiliac procedures was 14% (two of 14). Other major complications included transient renal failure in three patients that required short-term (two to eight times) dialysis, one arterial perforation and one dissection, and one prolonged intubation. No myocardial infarctions or strokes occurred. After major complications or identification of limitations in the study, the protocol was modified with the approval of the FDA to help avoid the recurrence of the same problems. There were no deaths or complications in the trauma cases. Conclusions: Contrast-enhanced CT (axial images and spiral reconstructions) was the most accurate method to determine candidacy for aortoiliac procedures and to choose the site for deployment of the devices. Angiographic scans were misleading in several patients regarding the critical determinants of patient candidacy and device deployment, particularly regarding the presence of a distal aortic neck. Cinefluoroscopy was used in all patients and was particularly useful for determining the continuity of vascular structures and the anatomy of branch arteries and for enabling precise positioning of stent devices. Determination of fixation sites and assessing dimensional information by cinefluoroscopy and angiography were limited by inaccuracies produced by image magnification, parallax, and uniplanar views. IVUS was used to determine the morphologic features of vascular structures (i.e., calcium, thrombus), to perform real-time observation of the expansion of devices, and to assure firm fixation of balloon-expanded stents before the procedures were completed. Duplex scanning was very helpful in assessing and identifying precisely the location of arteriovenous fistulas before intervention and provided assessment at follow-up intervals. Three-dimensional reconstruction imaging technologies such as spiral CT were particularly helpful for assessing the morphologic features of vascular anatomy before the intervention and at follow-up intervals, whereas 3-D IVUS provided a similar real-time perspective during the procedure. (J Vasc Surg 1996;24:556-71.)

Purpose: To illustrate the utility of intravascular ultrasound (IVUS) imaging during endoluminal interventions in the carotid artery. Methods and Results: A patient with symptomatic internal carotid artery occlusive disease was treated with balloon angioplasty and evaluated with both angiography (interpreted as a widely patent outcome) and IVUS, which identified a residual 70% cross-sectional area stenosis. A stent was placed across the lesion, producing a 70% increase in the lumen as documented by IVUS in comparison to the cross-sectional area of the reference vessel. Postprocedural angiography of the stented segment showed only an approximate 20% increase in diameter. Conclusions: This study highlights the utility of IVUS for accurate assessment of angioplasty outcome and for quantitative assessment of luminal volume following intervention and stent placement. The case emphasizes the need for IVUS as an integral part of the procedure to ensure adequate treatment and to accurately document the residual lesion for assessment of recurrence phenomena at follow-up.

Purpose: This study compares the utility of cineangiography and real-time intravascular ultrasonography (IVUS) in achieving successful deployment of endovascular prostheses. Methods: Five types of 5 cm long, 8 mm internal diameter polyester vascular grafts were secured in the infrarenal aorta of mongrel dogs by 18 mm long Palmaz balloon expandable vascular stents sutured to each end of the prostheses. The endovascular prostheses were delivered by crimping the stents at the ends of the grafts onto a 10 mm outside diameter, 8 cm long polyethylene balloon-dilation catheter. Real-time IVUS of the procedure was provided by a 0.035-inch, 20 MHz imaging element passed through the guide wire lumen in the balloon catheter. Two prostheses of each type were implanted, with one removed at 30 days and the other at 60 days for analysis. Results: At implantation, both angiography and IVUS provided information regarding the choice of site for placement of the device and sizing of the aortic lumen. Real-time IVUS enhanced the information obtained by cineangiography by displaying tomographic views of the vessel anatomy, enabling determination of cross-sectional areas, assessing full stent expansion, and providing information regarding surface topography along the length of the prostheses. Several critical observations were apparent only on IVUS, including incomplete initial stent expansion during two procedures evidenced by pulsation of the aortic wall independent of the stent and movement of unstented segments of thin-walled grafts. Some of these observations led to further interventions at the time of deployment. At death, a comparison of cineangiography, IVUS, and ultrafast computed tomography outlined lumenal continuity and areas of irregularity, thrombus, or narrowing, with IVUS being more sensitive than cineangiography or computed tomography for determining most parameters. Conclusions: We conclude that IVUS is a promising alternative method for precise placement of intravascular grafts. (J V ASC S URG 1995;21:365-74.)

Endovascular graft repair for aortic aneurysms has led to concerns regarding the healing characteristics of the graft within a thrombus-lined aneurysm and the effect that collateral flow may have on the endoluminal prosthesis and the aneurysm. An anterior aortic patch aneurysm model that preserved collateral arteries was examined and modified to address these issues. In canines (n = 30) a Dacron knitted patch (n = 27) or a rectus fascia patch (n = 3) was sutured into a 3.5-cm anterior aorotomy. Dacron patch aneurysm diameter was an average of 21.8 +/- 2.2 mm (mean canine normal aortic diameter 9.06 +/- 0.79 mm). Canines underwent angiogram, computed tomography, and/or intravascular ultrasound from 1 to 11 weeks later, at which time an endoluminal prosthesis was deployed and followed 30 to 60 days until harvest. Aneurysms accumulated minimal thrombus through the initial 11 weeks. Significant stenosis (mean 21.2% +/- 19%) occurred at aneurysm necks in association with a patch imbrication suture technique (n = 11). Following modification (n = 16), this decreased to a mean of 3.6 +/- 9.7%. Collateral lumbar artery patency was 95% at the time of imaging prior to graft placement. Following successful graft implantation, 16 of 18 aneurysms were filled with thrombus and in most cases the collateral circulation occluded. One of three fascial patch aneurysms ruptured 21 days after creation. This model more accurately depicts abdominal aortic aneurysms with the inherent thrombus and collateral flow that is important when studying aspects of endovascular aortic graft repair.

Background Previous studies have shown that long-term oral daily PDE 5 inhibitors (PDE5i) counteract fibrosis, cell loss, and the resulting dysfunction in tissues of various rat organs and that implantation of skeletal muscle-derived stem cells (MDSC) exerts some of these effects. PDE5i and stem cells in combination were found to be more effective in non-MI cardiac repair than each treatment separately. We have now investigated whether sildenafil at lower doses and MDSC, alone or in combination are effective to attenuate LV remodeling after MI in rats. Methods MI was induced in rats by ligature of the left anterior descending coronary artery. Treatment groups were: “Series A”: 1) untreated; 2) oral sildenafil 3 mg/kg/day from day 1; and “Series B”: intracardiac injection at day 7 of: 3) saline; 4) rat MDSC (106 cells); 5) as #4, with sildenafil as in #2. Before surgery, and at 1 and 4 weeks, the left ventricle ejection fraction (LVEF) was measured. LV sections were stained for collagen, myofibroblasts, apoptosis, cardiomyocytes, and iNOS, followed by quantitative image analysis. Western blots estimated angiogenesis and myofibroblast accumulation, as well as potential sildenafil tachyphylaxis by PDE 5 expression. Zymography estimated MMPs 2 and 9 in serum. Results As compared to untreated MI rats, sildenafil improved LVEF, reduced collagen, myofibroblasts, and circulating MMPs, and increased cardiac troponin T. MDSC replicated most of these effects and stimulated cardiac angiogenesis. Concurrent MDSC/sildenafil counteracted cardiomyocyte and endothelial cells loss, but did not improve LVEF or angiogenesis, and upregulated PDE 5. Conclusions Long-term oral sildenafil, or MDSC given separately, reduce the MI fibrotic scar and improve left ventricular function in this rat model. The failure of the treatment combination may be due to inducing overexpression of PDE5.

Endovascular placement of stents lined with prosthetic vascular graft materials offers promise in the treatment of dissections, aneurysms, and atherosclerotic occlusive disease. This study reports the development of and initial experience with polytetraflu oroethylene (PTFE) graft-stent devices endoluminally deployed in canines. Each iliac artery in 6 heparinized dogs received a 6-mm-diameter tubular PTFE graft mounted on either an 8 mm Palmaz stent (PS) or a metallic-ringed graft attachment device (GAD). The graft-stent devices were introduced from the femoral artery through a 14 Fr delivery catheter. Positioning and balloon expansion of the graft-stent devices were aided by fluoroscopic and intravascular ultrasound (IVUS) assessment. Animals were studied acutely (n = 2) or at weeks 1, 2, 4, or 8 after placement. No interval anticoagulation was used. All 6 PTFE-PS devices remained patent. Two of 6 PTFE-GAD devices occluded (at two and four weeks, respectively) owing to initial inadequate deployment. Nonoccluding thrombus was present in an additional 2 PTFE-GAD devices (acute and at one week, respectively) and in 2 PTFE-PS devices (at one week and two weeks, respectively). Complications included groin hematomas in 2 animals (at one week and two weeks, respectively) caused by the large traumatic delivery catheter. Endoluminal placement of PTFE graft-stent devices is feasible. Accurate assessment of deployment by IVUS, reduction of delivery catheter size, and improved graft-stent design are required.

Intravascular ultrasound (IVUS) imaging during peripheral endovascular interventions adds important information regarding the distribution of disease by providing controlled measurements of the cross-sectional area of the vessel lumen and wall prior to and following procedures. IVUS is useful in determining the mechanism and efficacy of balloon angioplasty, in guiding atherectomy devices, and in assuring appropriate placement of intravascular stents. The incorporation of an IVUS element into catheter-based interventional devices may improve the immediate and long-term results of endovascular interventions by decreasing complications from dissection and perforation of the arterial wall. Combined IVUS-stent prototype catheters are being developed to enable imaging and deployment simultaneously. Similar devices are being explored to enhance expedient, precise delivery of endoluminal grafts. Future studies of endovascular techniques should include IVUS, when possible, to accurately quantitate the initial efficacy of devices and to determine the nature and distribution of recurrent lesions.

This report compares the information obtained from arteriography, CT scans, and intravascular ultrasound evaluation of an abdominal aortic aneurysm. The two- and three-dimensional imaging techniques described in this report add information that is redefining the pre- and intraoperative analysis of arterial lesions. The new data may have an influence on the evolution of diagnostic methods and future interventional therapy for vascular disease. This case highlights the developing potential of the methods.

This preliminary report describes formation of femoral arterio-venous fistulas (n = 10) in six dogs using a 1.32-microns wavelength Nd:YAG laser welding technique. Stay sutures (6-0 polypropylene) were placed at 5-7 mm intervals along the anastomoses for vessel apposition. Delivery of laser energy through a 400-microns diameter fiber optic was controlled by a new computer-based software system. At 3 mm distance above the anastomosis, energy fluences of 110-260 J/mm2/cm length of anastomosis were used for laser welding. One or two additional hemostatic sutures were required in seven of the ten anastomoses. Flow was maintained for 1-2 hours prior to tissue harvesting. No thrombosis or delayed anastomotic failures were observed after initial welding and repair. Histologic examination revealed good apposition and adherence between wall layers and a fibrinous coagulum at the intimal junctions. Mild thermal injury of the wall was present at some anastomoses. This early investigation suggests that a 1.32 microns Nd:YAG laser welding technique can successfully create large vessel arteriovenous fistulas in the canine.

This canine study (n = 6) evaluated the acute and chronic effects of Nd:YAG laser prostatectomy using a Prolase II fiber. The Prolase II device consists of a 1,000 μm quartz fiber which directs a cone of Nd:YAG laser energy, at 45° to the axis of the fiber, into the prostatic urethra under direct visual guidance [visual laser ablation of prostate, (VLAP)]. Under visual guidance and saline irrigation, 60 seconds of 60 watts of laser power was delivered at 3, 6, 9, and 12 o'clock positions (14,400 J). One canine was instrumented but received no laser energy (control). One prostate was harvested acutely. The remaining four laser-treated dogs were evaluated at 6 to 16 weeks. The histopathology of acute laser effects shows areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 12.6 mm into the prostate. Two of the four dogs developed urinary retention at 6.5 and 9 weeks. On examination, both were found to have fibrotic strictures at the distal prostatic urethra with markedly dilated proximal prostatic urethral lumens (1.98 and 2.8 cm). Two other dogs showed no signs of urinary retention at sacrifice. Histopathology, both the 6 and 16 week laser-treated animals without urinary retention demonstrated dilated prostatic urethras with maximum cross-sectional diameters of 1.52 and 1.50 cm, respectively. However, the 16 week dog demonstrated mild distal urethral narrowing by urethrogram. The control dog demonstrated normal histology of the prostate at 16 weeks. This study demonstrates the safety and initial results of a delivery device for trans-urethral laser prostate ablation in a canine model. Further studies are needed to evaluate the cause of the fibrotic urethral strictures in this model and determine its clinical relevance. © 1994 Wiley-Liss, Inc.

Objective True and false lumen changes and patient outcomes following thoracic endovascular aortic repair (TEVAR) for patients with stable type B dissection have been described by the The Investigation of Stent Grafts in Aortic Dissection (INSTEAD) trial. However, these changes have not been described in TEVAR patients treated for complications of chronic dissection. Methods A single-institution study was conducted of 73 prospectively evaluated patients treated for complications of chronic type B dissection from 2002 to 2010. Spiral computed tomography reconstructions using M2S (Medical Media Systems, West Lebanon, NH) were analyzed for sequential changes in aortic volume and diameter during patient follow-up. Changes in aortic volume and diameter were tabulated as a percent change from preoperative values. Patient outcomes were determined by sequential evaluations postprocedure. Results TEVAR was successfully performed in 72 out of the 73 patients (99%). Indications for intervention were aortic enlargement (n = 62), failure of medical management (n = 7), and perforation (n = 4). The 30-day all-cause mortality rate was 14%; events were due to retrograde dissection (n = 4), cardiac-related (n = 4), and rupture (n = 2). Eleven out of the 72 patients (15%) required a secondary procedure for endoleak (n = 7) and persistent distal perfusion of the false lumen (n = 4). Mean percentage expansion of the thoracic true lumen was noted during the follow-up period: 38%, 46%, 71%, and 114% at 1-, 3-, 6-, and 12-month follow-up, respectively. Concomitant regression of the thoracic false lumen of −65%, −68%, −84%, and −84% was observed at the same intervals, respectively. Patients with an initial extension of the thoracic dissection into the infrarenal aorta (n = 46) had an increase in mean percentage change of aortic diameter and volume to 21% and 17% at 1 year, respectively. By contrast, in the patient group without infrarenal dissection (n = 14), the infrarenal aortic diameter and volume remained relatively unchanged at 3% and −0.9%, respectively, at 1-year postintervention. Conclusions TEVAR is a potential treatment option for patients experiencing complications of chronic type B dissection. During follow-up, there is a predictable expansion of the thoracic true lumen and regression of the thoracic false lumen. These findings correlate with those of the INSTEAD trial, which demonstrated false lumen regression and true lumen expansion in a cohort of patients with stable type B dissection. However, many patients with extension of thoracic dissection into the infrarenal aorta demonstrate continued aortic dilation and, on occasion, the need for secondary intervention for persistent distal perfusion. Further analysis is needed in this subgroup of patients so as to better determine potential predictors and the clinical significance of post-TEVAR infrarenal expansion. Moreover, further investigations may support a role for secondary endovascular intervention in remedying persistent infrarenal aortic expansion after TEVAR for chronic dissection.

Twelve cadaveric vertebral specimens were imaged after holmium yttrium aluminum garnet (Ho:YAG) laser diskectomy to determine the usefulness of magnetic resonance (MR) imaging in evaluating treatment outcome. The Ho:YAG laser was operated at 1.0-2.0 J per pulse, 5 Hz, and 250-microseconds pulse width. The total energy varied between 600 and 2,700 J. Two distinct patterns emerged on MR images. Tissue ablation at higher power (1.5 and 2.0 J per pulse) produced discrete signal voids that correlated with areas of laser-induced ablation identified at gross inspection. More subtle changes, characterized by a high-signal-intensity ring, were seen in the specimens lased at 1.0 J per pulse. The latter appearance corresponded to incomplete vaporization of diskal tissue, a broader zone of minimal thermal injury, and sparing of adjacent vertebral endplates. Total mass loss did not appear to be affected by the choice of power setting (1.0 vs 1.5 J per pulse), with total laser energy held constant.

UNLABELLED This study evaluated the strength of laser-welded arteriovenous shunts established using St. Jude BioPolyMeric vascular grafts. The arterial anastomoses of the biological graft were laser welded with and without the addition of soluble collagen or fibrin sealant. In four dogs, 16 arteriovenous grafts were implanted between the femoral artery and vein or the carotid artery and jugular vein using a 6 cm long, 4 mm internal diameter prosthesis. The 16 arterial anastomoses were evenly divided into four groups: sutured control, laser welded (LW), LW with soluble collagen applied immediately before and during welding, and LW with fibrin sealant applied after welding. All arterial control and venous anastomoses were sutured using continuous 6-0 polypropylene suture. All LW anastomoses were initially divided into six 5 mm long segments using six evenly spaced 6-0 polypropylene stay sutures. Each segment was laser welded using 15 to 18 5-sec pulses of the 0.5 W (7.5 W/cm 2) argon laser energy delivered via a 300 mum fiber while cooling the tissue with slow-drip saline irrigation. Blood flow was established and maintained through each anastomosis for 1 h. The vessels were then controlled, and anastomotic bursting pressure was determined with infusion of heparinized blood. RESULTS An additional hemostatic suture was required in 3 LW anastomoses (2 LW, 1 LW with collagen). Mean bursting pressures (mm Hg) of the arterial anastomoses were as follows: sutured controls 165 +/- 159, LW 144 +/- 58, LW and collagen 93 +/- 47, LW and fibrin sealant 181 +/- 45.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue fusion using laser energy is a promising new technology that may improve the healing of anastomoses. This study evaluated the feasibility of using argon laser energy to fuse vascular tissue and biologic vascular prostheses (St. Jude Medical, Inc.) in a canine arteriovenous (A-V) fistula model. Five animals had 4-cm length, 3-mm internal diameter grafts (n; eq 10) placed bilaterally as side-to-side A-V interpositions from the femoral artery to femoral vein. One A-V graft was placed using argon laser energy with the vessel edges aligned by 6-0 polypropylene traction sutures at 3 to 4 mm intervals. The contralateral graft was sutured using running 6-0 polypropylene suture. Anastomoses were successfully fashioned in all animals except for episodes of delayed bleeding at two laser-fused segments (15 min and 2 hrs) and one segment in a suture control (6 days). The implants were removed to evaluate the integrity and healing of the anastomoses at 2 hrs, 8 days, and at 7, 9, and 11 weeks. In all instances, there was no evidence of anastomotic dehissance or enlargement. Histologic examination of the anastomoses revealed coapted vessel and prosthetic edges in laser-fused specimens and a limited foreign-body response to the permanent sutures in the suture controls. In the longer term specimens there was marked intimal proliferation at the venous anastomosis in all implants, with recent bilateral occlusions of the 7 and 11 week implants at the venous connection. We conclude that laser fusion of biologic vascular prostheses to autogenous vessel is possible with healing and no evidence of anastomotic dehissance.(ABSTRACT TRUNCATED AT 250 WORDS)

There has been an enormous increase in the variety and volume of information encountered in surgical practice, either as measurable clinical variables or laboratory research data over the last three decades. Despite its form and origin, this information remains the basis of both daily clinical decision making and analytical research. Inferences drawn from past experience will modify an individual's approach to disease and treatment. However, when the demands of information processing cannot be met, mischief begins and quality of care declines. Modern computers offer an extraordinarily powerful method of processing the large volumes of medical data that are acquired, and provide techniques for analysis that would have been impossible, and often inconceivable, without computers. The applications of computer technology to surgical data management range from such simple and repetitive tasks as practice administration and accounting to elegant statistical and image analysis. This paper outlines the utility of computerized data management in clinical surgery and surgical research, and describes techniques for designing and implementing a customized surgical database system.

Postoperative assessment of vascular surgical reconstructive procedures is most commonly performed by means of Doppler flowmetry or manual pulse palpation. Because these techniques are intermittent and can be subjective, the authors have investigated the application of a piezoelectric pulse sensor in monitoring distal pulses continuously in patients undergoing limb revascularization. By placing a piezoelectric sensor on the skin overlying an artery, systolic displacement of the underlying vessel wall and tissue is converted into a graphically displayed real-time waveform. Hardcopies of the waveforms (n = 90) were obtained at hourly postoperative intervals from a total of 10 patients undergoing vascular surgery for occlusive disease. In all cases, continuous monitoring confirmed ongoing patency of the reconstructions, despite impalpable distal pulses in 60% of the patients. The amplitudes of the waveforms increased (mean = 18%, range = 6% to 33%) during the first eight postoperative hours. Because of the small size and sensitivity of the sensor, this technique was especially useful in patients with foot lesions requiring occlusive dressings, or where sequential stenoses prevented accurate assessment of postoperative circulation by manual palpation or Doppler examination. The authors conclude that continuous postoperative piezoelectric pulse monitoring allows accurate, continuous assessment of limb revascularization and alleviates the subjective, time-consuming observations by physicians and ancillary personnel.

This study reports three-dimensional reconstruction of two-dimensional intravascular ultrasound images obtained along 5 cm vessel segments. Each three-dimensional image was produced by computerized "stacking" of a set of consecutive two-dimensional images (mode 90 images per set; range 32 to 256). Three-dimensional images ( n = 26) were obtained from 11 human normal and atherosclerotic arteries (three in vitro and eight in vivo) and five in vivo canine studies. In vivo human examinations included three iliac, one deep, and three superficial femoral arteries and one aortic dissection. Five in vivo canine vessels (three iliac stenoses and two aortic dissections) were imaged before and after intraluminal stent deployment. Images were displayed on a gray-scale monitor, allowing examination of vessel images as complete cylinders or longitudinal hemisections in any user-defined plane. This enabled global examination of vascular segments and identified luminal shape, wall thickness, and distribution and morphology of plaques. Reconstructions of aortic dissections illustrated the extent of the dissection and produced an anatomic picture of the false lumen. Three-dimensional imaging enhanced stent deployment by identifying the site for deployment, dimensions of the vessel lumen, and changes in morphology after stent insertion. There was good correlation in vessel dimensions measured by angiography, two-dimensional intravascular ultrasonography and longitudinal gray-scale reconstructions ( r = 0.74 to 0.95; p = 0.34 to 0.001) but poor correlation with measurements from three-dimensional surface-rendered images ( r = 0.13 to 0.48; p = 0.42 to 0.87). We conclude that three-dimensional intravascular ultrasound imaging is an innovative new method for identifying the type, extent, and spatial configuration of arterial disease, with promising diagnostic and therapeutic applications. (J Vasc Surg 1992;16:509–19.)

This report describes intravascular ultrasound imaging of a localized 81% stenosis in the left common iliac artery of a 52-year-old woman. The lesion was dilated using an 8 mm balloon and was imaged pre- and post-dilatation using arteriography and a 5F, 30 Mhz intravascular ultrasound catheter. The same site was imaged again intraoperatively at two months following the initial procedure using an 8F, 20 Mhz intravascular ultrasound catheter when the patient had a femoropopliteal bypass for continuing ischemia. Intravascular ultrasound imaging allowed accurate, sequential, on-line calculation of the cross-sectional area and volume of the lesion both, acutely and following healing of the site. The morphology of the fractured arterial plaque was clearly defined, demonstrating distribution of calcification, and intraluminal flaps not apparent on arteriography. The case demonstrates the unique potential of intravascular ultrasound in assessing the immediate effect of interventions and evaluating the long-term healing.

Percutaneous discetomy has become a viable alternative in the treatment of herniated intervertebral disc. This study determined the effectiveness of holmium:YAG laser for ablation of human disc tissue. Human cadaveric intervertebral disc was harvested and stored in cold saline-soaked gauze for evaluation within 24 hr of removal. Using a specially designed apparatus, a 600 μm diameter fiber was advanced perpendicular through the annulus fibrosis at a controlled force of 0.098 Newtons (10 g). Samples were lased in air (n = 17) and in room temperature saline (n = 32). The laser energy was delivered at 5 Hz, 250 μsec pulsewidth, and from 50 mJ/mm2 to 1,100 mJ/mm2 fluence. Three to six holes were lased using identical parameters in each tissue specimen and were evaluated histologically and by morphometric analysis. The maximum zone of thermal necrosis and thermal denaturation occurred at 700–1,100 mJ/mm2; 140 μm and 590μm in air and 80 μm and 730μm in saline, respectively. At fluences between 200 and 700 mJ/mm2, the thermal necrosis ranged from 20 to 60 μm in air and from 10 to 50μm in saline, the zone of denaturation also being less. The holes created with the 600μm fiber were circular in shape, with a mean diameter of 500 μm (n = 3). The etch rates (penetration/pulse) appeared to increase with increasing fluences. In saline, the etch rate ranged from 7 to 53 μm/pulse (r = 0.57, P ≤ 0.10), and, in air, the values ranged from 7 to 65 μm/pulse (r = 0.79, P ≤ 0.03). No tissue ablation occurred at 50 mJ/mm2, suggesting that the ablation threshold lies between 50 and 200 mJ/mm2. This study demonstrates that controlled ablation of human disc tissue can be accomplished with the hol-mium:YAG laser, the degree of thermal injury being related to the amount of energy delivered.

The continuing evolution of endovascular techniques and instrumentation has enhanced the armamentarium available to vascular surgeons. The majority of endovascular procedures are minimally invasive with reduced risk and morbidity for the patient. However, imaging techniques, endovascular instrumentation, and delivery devices may introduce environmental safety concerns that were not present in conventional surgery. In this regard, it is essential that operating room personnel become knowledgeable about potential hazards and appropriate precautions that are necessary to create a safe work environment for themselves, as well as the patient.

Inferior vena cava filters are widely accepted for pulmonary embolic prophylaxis in high-risk patients with contraindications to anticoagulation. While long-term complications have been associated with permanent filters, retrievable filters are now available and have resulted in the rapid expansion of this technology. Nonetheless, complications are still reported with optional filters. Furthermore, device tilting and thrombus load may prevent retrieval in up to 30% of patients, thereby eliminating the benefits of this technology. The Crux vena cava filter is a novel, self-centering, low-profile filter that is designed for ease of delivery, retrievability and improved efficacy while limiting fatigue-related device complications. This device has been proven safe and user-friendly in an ovine model and has recently been implanted in human subjects.

Intraluminal ultrasound (ILUS) is a new catheter-based system which produces two-dimensional (2D), cross-sectional images of tubular structures. The principle of image acquisition using 5.0 Fr (30 MHz) and 8.0 Fr (20 MHz) ILUS catheters containing ultrasound transducers at the tip, is equally applicable to all tubular or hollow organs. This article illustrates the feasibility of intraluminal imaging of hollow organ structures, and describes computerized three-dimensional (3D) reconstruction of the 2D images, using a PC-based image analysis system. A set (n = 90) of longitudinally aligned, consecutive 2D images was sampled from various organs (canine bladder, urethra, jejunum, esophagus, and trachea) and computer processed to produce 3D images. By adjusting image density threshold and viewing angle, the lumen and wall morphology can be examined in any projection. Possible applications include diagnosis of lumen encroaching pathology, guidance of intraluminal instruments, and assessment of the effects of endoluminal interventions.

Long-term patency of vascular angioplasties is limited by stenosis from neointimal hyperplasia or progressive arteriosclerosis. This study evaluated the hypothesis that ASA (an antiprostaglandin) or Probucol (an antioxidant) may be useful in preventing stenosis following laser thermal angioplasty. Aortoiliac arteriosclerosis was induced in 17 female New Zealand white rabbits with a combination of endothelial denudation (4 Fr. Fogarty balloon catheters) and 2% cholesterol-supplemented diet for 6 weeks. All rabbits then underwent arteriography and were immediately randomized to one of three groups: Group I (n = 6), control, laser but no adjunctive therapy; Group II (n = 5), laser and ASA 10 mg/kg/day; Group III (n = 6), laser and 1% Probucol diet. Retrograde laser thermal angioplasty was performed with a 1-mm coronary Laserprobe. Six watts of argon laser energy was delivered for a single 5-sec pulse using a continuous motion from the right common iliac artery to the aorta. Pre- and postlaser arteriography was performed in all groups. Rabbits were sacrificed 1 month following laser angioplasty, and aortoiliac sections were taken after in situ perfusion fixation with paraformaldehyde and 0.05% glutaraldehyde. Serial 5-mm segments, proximal to the aortic bifurcation and distally from the same, were taken, stained, and evaluated by quantitative morphometry. From each segment, lesion area and lesion area/internal elastic laminae area were evaluated and compared. Serum cholesterol increased from 60.8 ± 19.5 to 1494.7 ± 12.7 mg% following institution of the cholesterol diet (P 11 14 stenosed iliac sections were enlarged (P 6 14 aortic lesions (P = NS). Aortic and iliac sections from all groups examined histologically 1 month after laser angioplasty showed no significant differences in lesion size and lesion area/IEL area. Laser angioplasty increases luminal size immediately, but neither the addition of ASA nor the addition of Probucol postoperatively affects final lesion size.

This study examines the biochemical changes that occur in argon laser-fused canine veins compared with control segments of vein. Laser fusions were formed using 0.5 W argon laser energy (1100-1500 J/cm2). Immediately following tissue fusion, blood flow was reestablished to test the integrity of the welds. 1-mm3 sections of the anastomoses and control sections were minced and protein extraction was performed by solubilizing the tissue in hot SDS Laemmli gel sample buffer. The proteins were separated electrophoretically on 5 and 10% polyacylamide SDS gels and silver stained. The analysis demonstrated significant biochemical differences between control and lased veins. We noted increases in several proteins after laser welding: the putative beta chain of type V collagen (5/5 gels), the putative gamma chain of type I collagen (4/5 gels), a 156-kDa protein (based on collagen molecular weight standards) 7/7 gels), an 82-kDa protein (8/9 gels), and several proteins of lower molecular weight (3/8 gels). The increases may be due to crosslinking of lower molecular weight proteins, degradation of higher molecular weight proteins, or increased solubility of certain proteins. These findings suggest that laser welding may occur by formation of crosslinks or by denaturation and reannealment of structural proteins.

This study investigated the feasibility of forming vascular anastomoses by use of argon laser tissue fusion and absorbable, monofilament polydimethylsiloxane guy sutures. In initial animal studies femoral arteriovenous fistulas approximately 1.5 cm in length were created bilaterally in each of 10 dogs and were studied histologically at 2, 4, 8, 16, and 24 weeks (two animals in each interval). In each animal, one anastomosis (control) was formed with continuous 6-0 polypropylene suture, and the contralateral anastomosis (experimental) was performed with an argon laser (0.5 watt, 5 to 7 minutes exposure, energy fluence 1100 to 1500 joules/cm2 per 1 cm length) with stay sutures of 5-0 polydimethylsiloxane at 0.5 to 0.65 cm intervals. At removal, all anastomoses were patent without hematomas, aneurysms, or luminal narrowing. Histologic examination at 2 to 16 weeks demonstrated resorption of the biodegradable suture material by a local inflammatory reaction. By 24 weeks, laser-fused specimens had no evidence of suture material at the anastomotic line, and healing consisted of a bond between artery and vein wall tissues. Control suture specimens at the same intervals exhibited an organized fibrous tissue response to the suture. Clinical adaptability of this technology has subsequently been evaluated in five patients at 10 to 27 months (21.6 +/- 5.8) by physical examination and duplex scanning and demonstrate no evidence of abnormal healing. This study establishes the experimental and preliminary clinical feasibility of laser-fused anastomoses aligned by biodegradable guy sutures and supports further investigation and refinement of the technique.

Over the last 3 years angioscopic techniques have been used to guide intraluminal instrumentation in 73 patients undergoing thrombectomy, nine patients with vascular trauma, and 32 patients during laser angioplasty and balloon dilation. After balloon-catheter thromboembolectomy residual, occlusive thrombi tightly adherent to the arterial wall were removed with flexible biopsy forceps in 13 of 73 (18%) patients; underlying intimal flaps were removed in another four. In nine patients traumatic intimal defects caused by iatrogenic cannulation injuries (n = 5) or external trauma (n = 4) were managed by thrombectomy followed by complete or partial intravascular removal of the intimal flap (n = 6) or dissection plane (n = 3) with long flexible forceps and rotating brushes. Traumatic intimal defects observed in two additional patients were judged to be too severe for endoscopic manipulation and required immediate bypass grafting. Inspection after angioplasty in 32 patients revealed wall charring and obvious thermal damage after laser procedures in 28 (87%) and plaque cracking, intimal flaps, and fragmentation in 26 (81%). These defects were underestimated on intraoperative angiography. Large flaps and thrombus were removed endoscopically in three. We conclude that angioscopic study reveals the extent of intimal injury and gives insights into mechanisms of instrumentation. Adherent thrombus after embolectomy by balloon catheter and intimal flaps caused by trauma or angioplasty are common and, if severe, can be successfully treated by endoscopic intravascular manipulation in selected patients.