The Layer Where the Coronary Arterial "Endarterectomy" Specimen Separates from the Underlying Artery

Described herein is a patient who had a coronary endarterectomy at the time of coronary artery bypass grafting. Histologic study of cross-sections of the endarterectomy specimen disclosed that the layer of separation of the endarterectomy specimen from the underlying native artery was in the media. This layer or plane of excision is virtually always the media irrespective of the artery having the endarterectomy. The procedure might better be called "endomediaectomy?"

Segmental Arterial Mediolysis with Preceding Symptoms Resembling Viral Infection Hampers the Differentiation from Polyarteritis Nodosa

A middle-aged man presented with a fever, arthralgia, gastrointestinal symptoms, headache, and rash. After two weeks, the patient suddenly complained of severe abdominal pain, and computed tomography revealed aneurysms in the hepatic and splenic arteries, which increased in size progressively. Given the elevated levels of inflammatory markers and orchitis, polyarteritis nodosa (PN) was initially suspected. Catheter embolization for the ruptured hepatic aneurysm and splenectomy for the large splenic ones were performed, and the pathological finding was consistent with segmental arterial mediolysis (SAM). Changes in inflammatory marker levels and aneurysmal size are also informative to differentiate SAM from PN.

[Hemothorax due to Idiopathic Rupture of Pulmonary Artery with Defect of Tunica Media]

A 47-years-old man with hemodynamic shock was refered to our hospital by an ambulance. Chest computed tomography(CT)showed left hemothorax and the extravasation of contrast media in his left lung. Emergency operation was done. A lot of intrathoracic hematoma and pulsating bleeding from the lung was found, and lingular segmentectomy was performed. Pathologically, the rupture of pulmonary artery of 2.2 mm in diameter was found without the finding of imflammation nor degeneration due to any basal diseases. Around the lesion, some artery of 0.3~3.0 mm in diameter showed defect of tunica media. This vascular anomaly was considered to lead his hemothorax.

Effects of removal of the adventitia of the descending aorta and structural alterations in the tunica media in pigs

OBJECTIVE

To investigate the effects of removal of the adventitia on the tunica media in a pig model.

METHODS

The experiment was performed in eight pigs. The adventitia of the descending aorta was removed. Following euthanasia, at two, four, six and eight weeks, the aortic segment was removed. Next, slices of the aorta were stained with hematoxylin and eosin (HE) and Weigert-Van Gieson.

RESULTS

After two weeks there was a slight cellular breakdown in the outer third of the media. After four weeks structural breakdown of elastic fibers was observed in the outer two thirds of the same layer. In six weeks, several areas of necrosis and almost complete disruption of elastic fibers were identified. Finally, after eight weeks, there was fibrosis of the entire wall with disruption of the internal elastic lamina.

CONCLUSION

The removal of the adventitia leads to degeneration of the media, determining loss of the normal structure of the aortic wall that is variable in its location, intensity and shape, depending on the length and duration of the ischemic insult.

Ascending aortic dissecting aneurysm with isolated right pulmonary arterial medial intramural hematoma

On rare occasions, acute aortic dissection may cause pulmonary artery obstruction when there is aortic rupture with hemorrhage into the common adventitia of the aorta and pulmonary artery. We report an extremely unusual case of an ascending aortic dissecting aneurysm associated with an isolated medial intramural hematoma in the right pulmonary artery in an 86-year-old woman with clinical manifestations mimicking pulmonary embolism. We believe that this rare pulmonary arterial complication of aortic dissection without involvement of the common adventitia has not been previously described.

Experimental study of a new vascular anastomotic technique in a swine model: short and mid-term results

This study reports the development of a new open external vascular stent: the lock stent device (LSD). It enables a novel end-to-end sleeve anastomotic technique, named locked anastomosis (LA). The LA technique consists of inserting a graft sleeve within an artery, secured in place by an internal stent and an external LSD. The internal stent, graft, vessel wall, and LSD are fastened together with single sutures. The LSD placement does not require a complete transection of the vessel wall as it can be enlarged and then relaxed to clasp the vessel neck. The tensile strength of the LA technique was accurately measured ex vivo and its stability successfully tested in vivo by acute pressure peak tests and mid-term survival studies. Ex vivo, the ratio between the tensile strength of the LA technique with two, three, and six stitches and that of hand-sewn anastomoses was 0.41 +/- 0.02, 0.59 +/- 0.17, and 1.03 +/- 0.04. In vivo, LA anastomoses tolerated marked increases in blood pressure (peak systolic pressure 195-230 mm Hg) for periods of 15-25 min without leakage. Five pigs survived 10 weeks with abdominal aorto-aortic bypass performed according to the LA technique with three stitches. Aortograms showed no narrowing or thromboses, and histological findings confirm uniform flattening of the aortic wall at the anastomosis, with proliferating neointima and uniformly hypotrophic media. Minimal changes were observed in the adventitia.

Adventitial cystic disease of the popliteal artery: a potential cause of intermittent claudication

Adventitial cystic disease (ACD) is an uncommon and rare vascular entity characterized by a highly viscous and mucinous cyst located in the adventitia of an artery. Although first described in the external iliac artery, the disease is more frequently sited in the popliteal artery. ACD characteristically occurs in young adults, mostly male, with intermittent claudication as the initial presenting symptom. As the cyst enlarges, it leads to vascular compression with stenosis or occlusion. Because cystic formation of the popliteal artery is uncommon, the disease is often unrecognized. We report a case of popliteal artery ACD in a 54-year-old woman who was successfully treated surgically.

Frequency and extent of media in the internal carotid artery in "endarterectomy" specimens

Carotid endarterectomy has been performed now for approximately 50 years. No report, however, has described the presence of media in these "endarterectomy" specimens. From January 1997 through May 2003, 147 carotid endarterectomy specimens were examined histologically. Portions of arterial media were present in each of them. The maximal amount of circumferential media in any patient varied from>95% of the cross-sectional circumference in 55 patients (37%) to<or=25% of the circumferences in 4 patients (3%). In 116 patients (79%), >75% of the arterial circumference of the internal carotid artery contained media. The proper term for this operative procedure might better be "endomediaectomy" rather than "endarterectomy."

Aneurysm of the Right Sinus of Valsalva After Aortic Valve Replacement in Takayasu Arteritis

We herein report a case with an aneurysm of the right sinus of Valsalva, which developed 14 years after an aortic valve replacement (AVR) for aortic regurgitation caused by Takayasu arteritis. The aortic wall around the right coronary artery ostium showed calcification, as a result, the modified Bentall procedure and coronary artery bypass to the right coronary artery were successfully performed. A pathological study of the resected aortic sinus wall showed a disruption of the elastic fibers in the media, granuloma formation, and a marked proliferation of the collagen fibers in the adventitia, and these findings were compatible with Takayasu arteritis. The development of an aneurysm of the sinus of Valsalva late after AVR indicates the necessity of a close and lifelong follow-up for patients with Takayasu arteritis, especially focusing on the aortic root morphology.

The Potential Role of Optical Coherence Tomography in the Evaluation of Vulnerable Carotid Atheromatous Plaques: A Pilot Study

PURPOSE

The decision to intervene surgically in patients with carotid artery disease is based on the presence of symptoms, along with the severity of carotid artery stenosis as assessed by ultrasound or X-ray computed tomography (CT). Optical coherence tomography (OCT) is a relatively new imaging technique that offers potential in the identification of, as well as the distinction between, stable and unstable atherosclerotic plaques. The purpose of our study was to evaluate whether OCT can be used as a noninvasive diagnostic tool to reveal the morphology of carotid stenosis from the adventitial surface of the carotid artery. To achieve this aim, excised atheromatous plaques were scanned by OCT from the external surface.

METHODS

Plaques removed at carotid endarterectomy were scanned by OCT from the external surface within 72 hr of surgery and then examined histologically. The images of the histologic slides and the scans were then compared.

RESULTS

We examined 10 carotid endarterectomy specimens and were able to identify calcification, cholesterol crystal clefts, and lipid deposits in the OCT images with histologic correlation. The strong light scattering from the calcified tissue and cholesterol crystal clefts limited the depth of light penetration, making observation of the intimal surface and the detail of the fibrous cap difficult. However, we were able to confidently identify the absence of an atherosclerotic plaque by OCT scans even from the external surface.

CONCLUSION

The results of this pilot study demonstrate that OCT can reveal the main features of carotid stenosis but that plaque vulnerability cannot be reliably and precisely assessed if scanned from the external surface with OCT in its present form.

Optimal dosing and duration of oral everolimus to inhibit in-stent neointimal growth in rabbit iliac arteries

BACKGROUND

Everolimus is an orally active derivative of sirolimus. Oral administration of rapamycin is efficacious in the reduction of neointima formation and clinical restenosis; however, its optimal dose and duration have not been determined.

METHODS

New Zealand White rabbits were divided into three groups. The first (low-dose) group received 1.5 mg/kg everolimus 1 day before stenting, followed by 0.75 mg/kg/day everolimus for 28 days. The second (high-dose) group received 6 mg/kg everolimus 1 day before, on the day of, and on the day after stenting, followed by 2 mg/kg/day for 4 days. The third (placebo) group received a matching volume of vehicle similar to that of Group 2. Twenty-eight days after stenting, animals were euthanized and morphometry was performed.

RESULTS

In the high-dose group, circulating everolimus levels corresponded with administrated dose levels; by Day 12, no circulating everolimus could be detected. In the low-dose everolimus group, levels remained constant up to 28 days. When compared with placebo, low-dose everolimus was associated with a significant reduction in medial thickness (32%), neointimal area (60%), and percent stent stenosis (33%); however, high-dose everolimus had no significant effect.

CONCLUSIONS

In conclusion, oral everolimus suppresses in-stent neointimal growth in rabbit iliac arteries. Four weeks of low-dose everolimus is more effective than 7 days of high-dose everolimus.

The Medial Wall of the Cavernous Sinus: Microsurgical Anatomy

OBJECTIVE:

This study was conducted to clarify the boundaries, relationships, and components of the medial wall of the cavernous sinus (CS).

METHODS:

Forty CSs, examined under ×3 to ×40 magnification, were dissected from lateral to medial in a stepwise fashion to expose the medial wall. Four CSs were dissected starting from the midline to lateral.

RESULTS:

The medial wall of the CS has two parts: sellar and sphenoidal. The sellar part is a thin sheet that separates the pituitary fossa from the venous spaces in the CS. This part, although thin, provided a barrier without perforations or defects in all cadaveric specimens studied. The sphenoidal part is formed by the dura lining the carotid sulcus on the body of the sphenoid bone. In all of the cadaveric specimens, the medial wall seemed to be formed by a single layer of dura that could not be separated easily into two layers as could the lateral wall. The intracavernous carotid was determined to be in direct contact with the pituitary gland, being separated from it by only the thin sellar part of the medial wall in 52.5% of cases. In 39 of 40 CSs, the venous plexus and spaces in the CS extended into the narrow space between the intracavernous carotid and the dura lining the carotid sulcus, which forms the sphenoidal part of the medial wall. The lateral surface of the pituitary gland was divided axially into superior, middle and inferior thirds. The intracavernous carotid coursed lateral to some part of all the superior, middle, and inferior thirds in 27.5% of the CSs, along the inferior and middle thirds in 32.5%, along only the inferior third in 35%, and below the level of the gland and sellar floor in 5%. In 18 of the 40 CSs, the pituitary gland displaced the sellar part of the medial wall laterally and rested against the intracavernous carotid, and in 6 there was a tongue-like lateral protrusion of the gland that extended around a portion of the wall of the intracavernous carotid. No defects were observed in the sellar part of the medial wall, even in the presence of these protrusions.

CONCLUSION:

The CS has an identifiable medial wall that separates the CS from the sella and capsule of the pituitary gland. The medial wall has two segments, sellar and sphenoidal, and is formed by just one layer of dura that cannot be separated into two layers as can the lateral wall of the CS. In this study, the relationships between the medial wall and adjacent structures demonstrated a marked variability.

Vascular Anastomosing by Gluing - an Experimental Study

BACKGROUND

Performing anastomoses by stitching is very time-consuming. We therefore looked for an alternative technique and used a relatively new surgical adhesive.

METHODS

Ten anastomoses between the aorta and a prosthesis were performed on five pigs (Deutsche Landrasse) using surgical glue (BioGlue). The proximal anastomoses between the abdominal aorta and the prostheses were performed end-to-side just below the renal arteries, the distal anastomoses in an end-to-end fashion just above the iliac bifurcation. The aorta between the anastomoses was ligated and resected. The animals were sacrificed between one week and up to four months after operation and anastomoses were analysed by angiography, CT angiography, angioscopy, and histology.

RESULTS

Angiography and CT angiography revealed that all anastomoses were patent. No aneurysms were found at the site of anastomoses. No haematomas were detected. Angioscopy revealed well-healed connections between the original aorta and the prosthesis.

CONCLUSIONS

We could demonstrate that anastomoses between the aorta and a prosthesis can be performed safely using a surgical adhesive. Further investigations of these anastomoses, especially over the long term, using calcified aortas, are necessary.

Flow-Induced Vascular Remodeling in the Mouse

Objective— Vascular remodeling of the carotid artery with intima-media thickness (IMT) is an important predictive factor for human cardiovascular disease. We characterized a mouse model of vascular remodeling.

Methods and Results— The left external and internal carotid branches were ligated so that left carotid blood flow was reduced to flow via the occipital artery. In response to partial ligation of the left carotid artery (LCA), blood flow significantly decreased (−90%) in the LCA and increased (+70%) in the right carotid artery (RCA). Morphometry showed that both RCA and LCA underwent outward remodeling that was maximal at one week. Remodeling was greater in the RCA with predominantly increased lumen and very little increase in media or adventitia. In the LCA there was a dramatic increase in media with adventitia growth and intima formation. Correlation analysis indicated that the outward remodeling was more likely due to primary changes in the vessel wall rather than to changes in the lumen, such as shear stress. Mechanistic studies suggested roles for macrophage infiltration, upregulation of matrix metalloproteinase (MMP)-9, extracellular matrix reorganization, and vascular smooth muscle cell proliferation in LCA remodeling.

Conclusions— The mouse model described here may be useful to define genetic determinants of IMT and identify new targets for therapy based on vascular remodeling.

Preintervention arterial remodeling affects vessel stretch and plaque extrusion during coronary stent deployment as demonstrated by three-dimensional intravascular ultrasound

The mechanisms of lumen enlargement during stent implantation may be significantly affected by arterial remodeling. To assess effects of lesion remodeling, we performed 3-dimensional intravascular ultrasound (IVUS) analyses in 55 coronary lesions before and after deployment of balloon-expandable stents. Standard quantitative analysis was performed, and arterial remodeling was assessed by the remodeling index (target site divided by mean of proximal and distal reference segment vessel areas), which classified lesions into group A (remodeling index < or =1, negative or intermediate remodeling, n = 40) or group B (remodeling index >1, positive remodeling, n = 15) lesions. Characteristics of the 55 patients and the interventional procedures were similar in the 2 groups. IVUS demonstrated that stenting resulted in increased lumen and vessel dimensions and in a reduced plaque size (p < or =0.001 each) in both group A and group B lesions. The extent of lumen increase inside the stents was almost identical, but resulted from different mechanisms: (1) vessel stretch was greater in group A (p <0.002 at minimum lumen site); (2) plaque compression (or embolization) tended to be greater in group B (p = 0.05, along entire stented segment); (3) plaque redistribution within the stent was observed in both groups (p <0.005 both); and (4) significant (p <0.01) plaque extrusion into the distal reference segment was found in group B only. Thus, the remodeling pattern of coronary lesions has a significant impact on the mechanisms of lumen enlargement during stent deployment. Lesions with positive remodeling show more plaque extrusion into the distal reference and less stent-induced vessel stretch than those with negative remodeling.

Matrigel-coated stents reduce intimal thickening in a large animal vascular stent model

BACKGROUND

Restenosis within vascular stents is primarily due to intimal thickening secondary to intimal hyperplasia (IH) which occurs maximally around stent struts. Dedifferentiation of vascular smooth muscle cells (VSMC) with subsequent migration and proliferation is believed to be a key event in IH formation. Matrigel (basement membrane protein) has been shown to inhibit dedifferentiation of VSMC in vitro. Our aim was to test the in vivo effect of Matrigel on IH formation using a novel sheep vascular stent model.

METHODS

Twenty vascular stents were implanted in the renal arteries of ten sheep. The left renal artery of each sheep was used to deploy uncoated stent and the right renal artery was used to deploy Matrigel-coated stent. Five sheep were analysed at four weeks and five at eight weeks after stent implantation. The sheep were sacrificed at the end of the study periods and the stented renal artery segments were examined by histology. Luminal, intimal and medial areas were determined using computer-assisted morphometric analysis.

RESULTS

All stent sites were widely patent without thrombosis. No luminal stenosis was seen angiographically. IH was quantified from histology cross-sections and expressed as an intima to media (I/M) ratio. The ratio was significantly reduced in the matrigel-coated sites at eight weeks (uncoated 0.49+/-0.23; Matrigel-coated 0.32+/-0.12; p value <0.05).

CONCLUSIONS

The sheep renal artery vascular stent model is feasible for the study of stent biology. IH was reduced by Matrigel-coated stents.

Induction of angiotensin converting enzyme in neointima after intravascular stent placement

BACKGROUND

To investigate the morphological changes of the arterial wall and the expression of angiotensin converting enzyme (ACE) in the arterial wall after stent placement in a canine model.

METHODS

Seventeen mongrel dogs underwent stent placement (Gianturco's Z stent) in the aorta. Six animals were sacrificed at 4 weeks after stent implantation, and the other 5 animals at 12 weeks. The normal aorta was harvested from 6 dogs. The specimens were stained with hematoxylin-eosin (H&E) as well as by immunohistochemistry (smooth muscle specific a-actin, and ACE). Histomorphometric analysis was performed using the sections stained with H&E and smooth muscle specific a-actin.

RESULTS

The total intimal area was significantly increased at all time points as compared with the control aorta. The a-actin positive intimal area was also significantly increased at all time points as compared with the control aorta. In the control aorta, luminal endothelial cells as well as a-actin positive medial cells occasionally exhibited faint cytoplasmic staining for ACE. In the 4- and 12-week stented aorta, a-actin positive cells in the neointima and media as well as macrophages in the adventitia stained strongly positive for ACE.

CONCLUSIONS

ACE was induced in the neointima after stent placement of the canine aorta. Considering its multiple biological actions, ACE may be associated with the pathogenesis of neointimal hyperplasia after stent placement.

A three-dimensional finite element model for arterial clamping

Clamp induced injuries of the arterial wall may determine the outcome of surgical procedures. Thus, it is important to investigate the underlying mechanical effects. We present a three-dimensional finite element model, which allows the study of the mechanical response of an artery-treated as a two-layer tube-during arterial clamping. The important residual stresses, which are associated with the load-free configuration of the artery, are also considered. In particular, the finite element analysis of the deformation process of a clamped artery and the associated stress distribution is presented. Within the clamping area a zone of axial tensile peak-stresses was identified, which (may) cause intimal and medial injury. This is an additional injury mechanism, which clearly differs from the commonly assumed wall damage occurring due to compression between the jaws of the clamp. The proposed numerical model provides essential insights into the mechanics of the clamping procedure and the associated injury mechanisms. It allows detailed parameter studies on a virtual clamped artery, which can not be performed with other methodologies. This approach has the potential to identify the most appropriate clamps for certain types of arteries and to guide optimal clamp design.

Flow-dependent remodeling in the carotid artery of fibroblast growth factor-2 knockout mice

OBJECTIVE

Fibroblast growth factor-2 (FGF2) has been implicated as a mediator in the structural remodeling of arteries. Chronic changes in blood flow are known to cause reorganization of the vessel wall, resulting in permanent changes in artery size (flow-dependent remodeling). Using FGF2 knockout (Fgf2(-/-)) mice, we tested the hypothesis that FGF2 is required during flow-dependent remodeling of the carotid arteries.

METHODS AND RESULTS

All branches originating from the left common carotid artery (LCCA), except for the left thyroid artery, were ligated to reduce flow in the LCCA and increase flow in the contralateral right common carotid artery (RCCA). Age- and sex-matched control animals did not undergo ligation of the LCCA branches. Morphometric analysis showed that by day 7, vessel diameter was significantly greater in the high-flow RCCA of FGF2 wild-type (Fgf2(+/+)) and Fgf2(-/-) mice versus the respective control RCCA, demonstrating outward remodeling. In contrast, vessel diameter was decreased by day 7 in the low-flow LCCA of both genotypes compared with the control LCCA, showing inward remodeling. No differences were observed between Fgf2(+/+) and Fgf2(-/-) mice in either high-flow or low-flow remodeling.

CONCLUSIONS

Given these results, we demonstrate that FGF2 is not essential for flow-dependent remodeling of the carotid arteries.

A layer-specific three-dimensional model for the simulation of balloon angioplasty using magnetic resonance imaging and mechanical testing

A detailed understanding of the mechanical procedure of balloon angioplasty requires three-dimensional (3D) modeling and efficient numerical simulations. We have developed a 3D model for eight distinct arterial components associated with specific mechanical responses. The 3D geometrical model is based on in vitro magnetic resonance imaging of a human stenotic postmortem artery and is represented by nonuniform rational B-spline surfaces. Mechanical tests of the corresponding vascular tissues provide a fundamental basis for the formulation of large strain constitutive laws, which model the typical anisotropic, highly nonlinear, and inelastic mechanical characteristics under supraphysiological loadings. The 3D finite-element realization considers the balloon-artery interaction and accounts for vessel-specific axial in situ prestretches. 3D stress states of the investigated artery during balloon expansion and stent deployment were analyzed. Furthermore, we studied the changes of the 3D stress state due to model simplifications, which are characterized by neglecting axial in situ prestretch, assuming plane strain states, and isotropic material responses, as commonly utilized in previous works. Since these simplifications lead to maximum stress deviations of up to 600%-where even the stress character may interchange-the associated models are, in general, inappropriate. The proposed approach provides a tool that has the potential (i) to improve procedural protocols and the design of interventional instruments on a lesion-specific basis, and (ii) to determine postangioplasty mechanical environments, which may be correlated with restenosis responses.

[Histomorphological structural changes of head and neck blood vessels after pre- or postoperative radiotherapy]

BACKGROUND

Patients with squamous cell carcinomas of the oral cavity are being increasingly treated by multimodal interdisciplinary regimes using a combination of surgery, chemo- and radiotherapy. Inflammatory alterations of the vascular endothelium following preoperative radiotherapy frequently cause healing delays of free flaps in the irradiated graft bed. The aim of the study was to investigate quantitative and qualitative changes of irradiated neck recipient vessels and transplant vessels used for microsurgical anastomoses in free flaps in patients undergoing preoperative radiotherapy or radiochemotherapy.

PATIENTS AND METHODS

In 348 patients (October 1995-March 2002) receiving primarly or secondary 356 microvascular hard- and soft tissue reconstruction, a total of 209 vessels were obtained from neck recipient vessels and transplant vessels during anastomosis. Three groups were analysed: group 1 (27 patients) treated with no radiotherapy or chemotherapy; group 2 (29 patients) treated with preoperative irradiation (40-50 Gy) and chemotherapy (800 mg/m2/day 5-FU and 20 mg/m2/day cisplatin) 1.5 months prior to surgery; group 3 (20 patients) treated with radiotherapy (60-70 Gy) (median interval 78.7 months; IQR: 31.3 months) prior to surgery. From each of the 209 vessel specimens, 3 sections were investigated histomorphometrically, qualitatively and quantitatively (ratio media area/total vessel area) by NIH-Image-digitized measurements. To evaluate these changes as a function of age, radiation dose and chemotherapy, a statistical analysis was performed using an analysis of covariance and chi 2 tests (p > 0.05, SPSS V10).

RESULTS

In group 3, qualitative changes (intima dehiscence, hyalinosis) were found in recipient arteries significantly more frequently than in groups 1 and 2. For group 3 recipient arteries, histomorphometry revealed a significant decrease in the ratio media area/total vessel area (median 0.51, IQR 0.10) in comparison with groups 1 (p = 0.02) (median 0.61, IQR 0.29) and 2 (p = 0.046) (median 0.58, IQR 0.19). No significant difference was found between the vessels of groups 1 and 2 (p = 0.48). There were no significant differences in transplant arteries and recipient or transplant veins between the groups. Age and chemotherapy did not appear to have a significant influence on vessel changes in this study (p > 0.05).

CONCLUSIONS

Following irradiation with 60-70 Gy, significant qualitative and quantitative histological changes to the recipient arteries, but not to the recipient veins, could be observed. In contrast, irradiation at a dose of 40-50 Gy and chemotherapy given at a median interval of 1.5 months prior to operation did not lead to significant histological changes to the recipient vessels.

External beam irradiation in angioplasted arteries of hypercholesterolemic rabbits. The dose and time effect

PURPOSE

To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model.

METHODS AND MATERIALS

Eight groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy 6 MV X-ray dose, (c) with a 18-Gy, (d) treated with balloon angioplasty, (e) dosed with 12-Gy half an hour post-angioplasty, (f) dosed with 18-Gy half an hour post-angioplasty, (g) dosed with 12-Gy 48 h post angioplasty, (g) dosed with 18-Gy 48 h post angioplasty.

RESULTS

External irradiation at either 12 or 18 Gy was not found to change vessel morphometry in noninjured arteries. The 12-Gy dose given soon after angioplasty further increased percentage stenosis (63% on the average), despite the preservation of the lumen cross-sectional area. Positive remodeling was not observed in arteries given 18-Gy half an hour post angioplasty to counterbalance the increased neointimal formation. Therefore, this treatment resulted in a drastic reduction in lumen area and in enhancement of percentage stenosis (84% on the average). On the contrary, the delayed irradiation of the angioplasted arteries at either 12 or 18 Gy was not found to influence any of the studied morphometric parameters 5 weeks after angioplasty.

CONCLUSIONS

Uniform external beam irradiation up to 18 Gy was well tolerated by intact femoral arteries. Prompt 12- or 18-Gy irradiations accentuated percentage stenosis. However the lumen cross-sectional area was preserved only at the lower dose point. Delayed irradiation at any dose did not influence the restenosis process.

Asymmetric medial degeneration of the intrapericardial aorta in aortic valve disease

BACKGROUND

A geometrical and functional asymmetry in the normal aortic root has been recently demonstrated. Whether the distribution of medial degeneration (MD) within the wall of the dilated ascending aorta in adult patients reflects such asymmetry, still has to be assessed.

METHODS

Nineteen patients with fibrocalcific aortic valve disease and dilatation of the intrapericardial aorta, without clinical signs and familiar history of primary elastic connective tissue disorders, underwent surgery. Biopsies (57 specimens) were taken in each patient from three areas of the ascending aortic wall distal to the three sinuses of Valsalva. MD lesions found at histology in each specimen were classified in three degrees. Comparisons were made between the three sites as to distribution of the three degrees and between one site and the other two as to incidence of the highest degree.

RESULTS

A mild degree of MD was found in 26 specimens (45.6%), moderate in 14 (24.6%), severe in 17 (29.8%). The distribution of the three degrees of MD changes was significantly different between one of the three studied wall areas and the other two (P<0.001): a significantly greater incidence of the highest degree of involvement in the aortic wall distal to the non-coronary sinus than in the wall areas corresponding to the coronary sinuses was found (P<0.001).

CONCLUSIONS

MD lesions in dilated intrapericardial aorta are more severe in the wall area distal to the non-coronary sinus, likely due to haemodynamic stress asymmetry.

Retaining the aortic fat pad during cardiac surgery decreases postoperative atrial fibrillation

BACKGROUND

Atrial arrhythmias are a common and serious complication of cardiac surgical procedures. Reports describing pericardiac neurogenic tissue led us to hypothesize that removal of the aortic fat pad could cause an autonomic imbalance and contribute to atrial arrhythmias following cardiac surgery.

METHODS

Patients (n=131) underwent either conventional cardiopulmonary bypass surgery (CPB) or off-pump coronary artery bypass (OPCAB) surgery. The aortic fat pad was either left intact or removed. The incidence of de novo atrial arrhythmias during the patient's hospital stay was tabulated. Patients with peri-operative myocardial infarction or pre-existing atrial or supraventricular arrhythmias were excluded.

RESULTS

Demographics, preoperative medications, ASA and NYHA classifications, and complication rates (other than for atrial arrhythmias) did not differ among the groups. The STS-predicted mortality was higher in the CPB/Fat-Pad-Removed group (2.23 +/- 1.89) than in either the OPCAB/Fat-Pad-Intact (1.09 +/- 0.80) or OPCAB/Fat-Pad-Removed (1.02 +/- 0.62) groups (p < 0.05). Atrial arrhythmias were present in 19 of 131 patients (14.5%). Logistic regression demonstrated a significantly elevated atrial arrhythmia rate when the fat pad was removed (odds ratio = 3.49, 95% bounds = 1.09 to 11.18, p = 0.035). Neither the pump status nor the cross product of pump status by fat pad status were significant in this pilot study.

CONCLUSIONS

Retaining the aortic fat pad during coronary artery bypass surgery is correlated with a decreased incidence of postoperative atrial arrhythmias.

[Can minimal arterial aggressions using non-penetrating mechanical clip suture prevent myo-intimal hyperplasia? Preliminary results]

SUBJECT

Vascular anastomosis is still associated with a significant rate of early (stenosis, thrombosis) and delayed (intimal hyperplasia) complications. Even though suture closure remains the most widespread standard procedure, many mechanical systems have been developed mostly using non penetrating clips, aiming to make the suture easier, to reduce the operating time and to reduce the scarring process of the arterial wall. We investigated the usefulness of non penetrating titanium Vascular Closure Staple (VCS) developed for peripheral blood vessels anastomosis, in a study on 20 rabbits with the small VCS system.

MATERIAL AND METHODS

On 20 rabbits, 9 of the aortic sutures were done with VCS clips and 11 were done by standard closure.

RESULTS

We found a significant improvement in the operating time of the closure (9 +/- 2 minutes versus 14 +/- 4 minutes), early and delayed (10 weeks) patency and the respect of the aorta diameter (0.248 +/- 0.01 centimetres versus 0.246 +/- 0.039 centimetres) and loss of surface (40.3 +/- 5.59% versus 45.6 +/- 6.34%). The main improvement is the reduced intimal hyperplasia (0.128 +/- 0.05 millimetres versus 0.198 +/- 0.032 millimetres. P=0.012).

CONCLUSION

Arterial closure can be performed more rapidly with VCS clips than with suture closure, and with a marked reduced reaction of intimal hyperplasia. With those elements it is necessary to continue the experimental studies and to evaluate the VCS sutures at mean and long term.

Saline flush during excimer laser angioplasty: short and long term effects in the rabbit femoral artery

BACKGROUND AND OBJECTIVE

In this study, the effect of flushing saline on arterial wall damage (medial ruptures and necrosis), intimal hyperplasia, and arterial remodeling was determined. During excimer laser coronary angioplasty saline is flushed to reduce the size of explosive water vapor bubbles formed by intraluminal delivery of excimer laser pulses in blood.

METHODS

In the femoral artery of the rabbit, 600 excimer laser pulses (308 nm, 50 mJ/mm2 per pulse, 20 Hz) were delivered coaxially over a length of 20 mm in 10 bursts of 3 seconds each. In 24/48 procedures, saline was flushed (0.2 ml/s) via the guidewire channel. After 2 and 56 days, microscopic and angiographic results were compared.

RESULTS

At 2 days, as compared to lasing in blood, saline flush had drastically reduced the incidence of dissections (2/12 vs. 11/12, P < 0.002), but had increased the extent of medial and adventitial necrosis. The latter is attributed to direct irradiation of the arterial wall. After 56 days, in the saline group, in the middle-distal part of treated segments, medial necrosis without intimal hyperplasia was observed. However, at the edges of these lesions, intimal hyperplasia and arterial shrinkage reduced the lumen.

CONCLUSION

Flushing saline during coaxial excimer laser pulse delivery significantly reduced the incidence of vessel wall ruptures, and prevented intimal hyperplasia formation in part of the lesion. The histologic findings at 56 days are attributed to the optical window which the saline flush provides for direct ultraviolet light irradiation of the arterial wall.

Genetic basis of variation in carotid artery wall thickness

BACKGROUND AND PURPOSE

Other than the documented associations of risk factors and carotid artery wall thickness, the genetic basis of variation in carotid artery intimal-medial thickness (IMT) is unknown. The purpose of this study was to examine the extent to which variation in common carotid artery (CCA) IMT and internal carotid artery (ICA) IMT are under genetic control.

METHODS

The sibship data used for this analysis were part of an epidemiological survey in Mexico City. The CCA and ICA analyses were based on 46 and 44 sibships of various sizes, respectively. The CCA and ICA IMTs were measured with carotid ultrasonography. Using a robust variance decomposition method, we performed genetic analyses of CCA IMT and ICA IMT measurements with models incorporating several cardiovascular risk factors (eg, lipids, diabetes, blood pressure, and smoking) as covariates.

RESULTS

After accounting for the effects of covariates, we detected high heritabilities for CCA IMT (h2 = 0.92 +/- 0.05, P = .001) and ICA IMT (h2 = 0.86 +/- 0.13, P = .029). Genes accounted for 66.0% of the total variation in CCA IMT, whereas 27.7% of variation was attributable to covariates. For ICA IMT, genes explained a high proportion (74.9%) of total phenotypic variation. The covariates accounted for 11.5% of variation in ICA IMT.

CONCLUSIONS

Our results suggest that substantial proportions of phenotypic variance in CCA IMT and ICA IMT are attributable to shared genetic factors.

Adventitial inversion technique in repair of aortic dissection

We describe a new technique for aortic anastomosis in the repair of acute dissection. The aorta is buttressed by inverting the adventitia without the use of Teflon or other synthetic materials. This technique provides a safe and secure anastomosis.

[Adventitia resection in cystic degeneration of the popliteal artery]

Adventitial cystic disease is a rare form of non-atherosclerotic stenosis of the popliteal artery. It is caused by synovial-like cysts in the subadventitial tissue layer of the arterial wall causing compression of the lumen. The cysts contain mucinous material similar to that found in joint-ganglia. Popliteal artery stenoses causing claudication in young patients is the leading symptom of this disease. The classical therapy is the surgical excision of the diseased artery and interposition grafting with saphenous vein. As an alternative method we present the technique of complete circumferential resection of the diseased adventitia to decompress the lumen of the artery by removing the cysts completely. This technique is called exarterectomy and has been applied in 2 patients. In both cases we could remove the cysts completely without opening the arterial lumen. Intraoperative arteriography documented complete decompression of the arterial lumen. Both patients presented with excellent results 6 months postoperatively without any symptoms or signs of recurrence. Late results of exarterectomy ar not yet available.