PubMed Health⌕ Search

Biomedical subjects

W M Abbott

Publications and source records attributed to W M Abbott.

At least 55 records · Page 3Linked to original sources
PubMed1995

Photodynamic therapy of vein grafts: suppression of intimal hyperplasia of the vein graft but not the anastomosis.

PURPOSE: There is no clinically useful therapy for the suppression of vein bypass graft intimal hyperplasia (IH). Photodynamic therapy (PDT), a technique that uses light to activate otherwise biologically inert photosensitizers to produce cytotoxic effects, has been demonstrated to successfully inhibit experimental IH in balloon-injured arteries. The purpose of this study was to investigate the efficacy of PDT as a method to reduce vein graft IH. METHODS: Reversed external jugular vein bypass grafts of the common carotid artery were performed in 28 male Sprague-Dawley rats. The animals received either chloroaluminum sulfonated phthalocyanine (2.5 mg/kg intravenously) 24 hours before the ex vivo irradiation of the vein grafts (VG) with 100 joule/cm2 at 675 nm (PDT VG) or saline solution as control (CON VG). Preharvest bromodeoxyuridine was administered to label proliferating cells. All vein grafts were perfusion fixed within 96 hours for a pilot study or at 2 and 4 weeks for the main study. Histology, immunohistochemistry, and morphometric analysis were performed. RESULTS: There was no acute thrombus formation in the hypocellular PDT VG with occasional platelets but no leukocytes adherent to the luminal surface. Intimal areas of the PDT VG were 18% at 2 weeks and 53% at 4 weeks of the CON VGs (p < 0.05). Medial areas and percent of stenoses were also significantly less in PDT than in CON VG. However, intimal hyperplasia noted in the longitudinal sections within 2 mm of the anastomoses did not demonstrate a difference between PDT and CON VG. Intimal hyperplasia of both PDT and CON VG consisted of smooth muscle cells, verified by immunohistochemistry. Bromodeoxyuridine-labeled cells were more abundant in 2-week than in 4-week specimens, were found most frequently in the intimal areas of the CON VG body, and were equivalent in the anastomoses of PDT VG and CON VG. CONCLUSIONS: These data suggest that PDT of vein grafts suppresses the development of IH in the body of the vein graft but does not affect IH adjacent to the anastomoses. The artery may be the source of proliferating smooth muscle cells that contribute to the anastomotic vein graft IH.

Anastomosis, Surgical↗
PubMed1995

Magnetic resonance angiography in the preoperative evaluation of abdominal aortic aneurysms.

PURPOSE: Contrast arteriography (CA) is a useful but invasive technique for the preoperative evaluation of patients with abdominal aortic aneurysms (AAA). To evaluate the use of magnetic resonance arteriography (MRA) as a preoperative study we prospectively studied 38 patients undergoing AAA repair. METHODS: All patients underwent biplane CA and MRA with use of a gadolinium-enhanced technique. Radiographic studies were then independently evaluated by blinded radiologists for anatomic findings with CA used as the standard. Studies were then independently evaluated by blinded vascular surgeons, and a surgical plan was made. RESULTS: With CA and intraoperative findings as the standards, MRA proved highly accurate in the determination of multiple key anatomic elements. The proximal extent of aneurysmal disease was correctly predicted in 87% (33/38) patients. Significant iliofemoral occlusive disease was identified with a sensitivity of 83% (5/6). Iliac or femoral aneurysms were detected with a sensitivity of 79% (22/28) and specificity of 86% (41/48). Significant renal artery stenosis was detected with a sensitivity of 71% (12/17) and a specificity of 99% (72/73). Accessory renal arteries were correctly identified in 71% (12/17). Surgeon evaluators correctly predicted the proximal cross-clamp site in 87% (33/38) of patients with use of MRA as compared with the actual operative conduct. Proximal anastomotic sites were correctly predicted in 95% (36/38) with MRA and 97% (37/38) with CA. Renal revascularization was predicted by MRA with a sensitivity of 91% (10/11) and specificity of 100% (65/65). The use of bifurcated aortic prostheses was correctly predicted by MRA in 75% (12/16), which was similar to that predicted by CA (81%, 13/16). CONCLUSIONS: MRA can provide preoperative anatomic information that is equivalent to CA for surgical planning. Because of favorable cost and patient safety considerations MRA will assume increasing importance in the preoperative evaluation of AAA.

Aged↗
PubMed1995

Simultaneous aortic and renal artery reconstruction: evolution of an eighteen-year experience.

PURPOSE: We reviewed an 18-year experience with combined abdominal aortic and renal artery reconstruction (AOR) with a particular focus on patients' clinical risk profile and surgical results in contemporary practice as compared with earlier experience. METHODS: One hundred seventy patients underwent AOR during the interval January 1, 1976 to June 30, 1994. To examine parameters representative of current practice, the cohort was divided into group I patients (n = 110) treated before 1990 and group II (n = 60) treated between 1990 and 1994. Median follow-up duration for the entire cohort was 8.4 +/- 0.6 years. Renal artery reconstruction patency and patient survival rates were calculated by life-table methods. Logistic and Cox regression analysis were used to determine predictors of perioperative and long-term morbidity/mortality rates. RESULTS: Although demographic features changed little over the review period, the detection (56% vs 73%, p = 0.03) and treatment with percutaneous transluminal coronary angioplasty/coronary artery bypass grafting (11% vs 40%, p = 0.0001) of associated coronary artery disease were more frequent in group I patients. The operative mortality rate for the entire cohort was 6.5% (group I = 9% vs group II = 2%, p = 0.06). Changing trends of surgical techniques over the review period included (group I vs II, respectively) increased use of bilateral simultaneous renal artery repair (12% vs 25%, p < 0.005) and transaortic endarterectomy as the renal artery reconstruction technique (3% vs 25%, p < 0.0001). Favorable response in blood pressure control was noted in 68% of group II patients. The cumulative 5-year survival rate for all patients was 75% with an initial serum creatinine of 2.0 mg/dl or greater being the only negative predictor of late survival after regression analysis. CONCLUSION: The current operative mortality rate for AOR is in the range anticipated for aortic surgery alone, and this appears to be related to improved detection and treatment of associated coronary artery disease and intervention before major deterioration in renal function. These findings coupled with currently available natural history data relative to renovascular disease justify an aggressive approach with AOR when significant renal artery stenosis is detected during evaluation of aortic disease.

Aged↗
PubMed1995

Comparative early and late cardiac morbidity among patients requiring different vascular surgery procedures.

PURPOSE: The evaluation of coronary artery disease (CAD) in patients undergoing vascular surgery can provide information with respect to perioperative and long-term risk for CAD-related events. However, the extent to which the required surgical procedure itself imparts additional risk beyond that dictated by the presence of CAD determinants remains in question. The purpose of this study was to quantify the relative contributions of specific vascular procedures and CAD markers on perioperative and long-term cardiac risk. METHODS: The study cohort comprised 547 patients undergoing vascular surgery from two medical centers who underwent clinical evaluation, dipyridamole thallium testing, and either aortic (n = 321), infrainguinal (n = 177), or carotid (n = 49) vascular surgery between 1984 and 1991. Perioperative and late cardiac risk of fatal or nonfatal myocardial infarction (MI) was compared for the three procedures before and after adjustment for the influence of comorbid factors. These adjusted estimates may be regarded as the component of risk because of type of surgery. RESULTS: Perioperative MI occurred in 6% of patients undergoing aortic and carotid artery surgery, and in 13% of patients undergoing infrainguinal procedures (p = 0.019). Significant (p < 0.05) predictors of MI were history of angina, fixed and reversible dipyridamole thallium defects, and ischemic ST depression during testing. Although patients undergoing infrainguinal procedures exhibited more than twice the risk for perioperative MI compared with patients undergoing aortic surgery (relative risk: 2.4[1.2 to 4.5, p = 0.008]), this value was reduced to insignificant levels (1.6[0.8 to 3.2, p = 0.189]) after adjustment for comorbid factors. There was little change in comparative risk between carotid artery and aortic procedures before (1.0[0.3 to 3.6, p = 0.95]) or after (0.6[0.2 to 2.3, p = 0.4]) covariate adjustment. The 4-year cumulative event-free survival rate was 90% +/- 2% for aortic, 74% +/- 5% for infrainguinal, and 78% +/- 7% for carotid artery procedures (p = 0.0001). Predictors of late MI included history of angina, congestive heart failure, diabetes, fixed dipyridamole thallium defects, and perioperative MI. Patients undergoing infrainguinal procedures exhibited a threefold greater risk for late events compared with patients undergoing aortic procedures (relative risk: 3.0[1.8 to 5.1, p = 0.005]), but this value was reduced to 1.3(0.8 to 2.3, p = 0.32) after adjustment. Long-term risk among patients undergoing carotid artery surgery was less dramatically altered by risk factor adjustment. CONCLUSION: In current practice, among patients referred for dipyridamole testing before operation, observed differences in cardiac risk of vascular surgery procedures may be primarily attributable to readily identifiable CAD risk factors rather than to the specific type of vascular surgery. Thus the cardiac and diabetic status of patients should be given careful consideration whenever possible, regardless of surgical procedure to be performed.

Aged↗
PubMed1995

Intraoperative determinants of infrainguinal bypass graft patency: a prospective study.

OBJECTIVES: To evaluate a number of currently available methods for intraoperative assessment of infrainguinal bypass grafts (IBG) in terms of detecting technical errors and predicting graft failure. DESIGN: Prospective open clinical study. METHODS: Forty-nine patients undergoing 54 consecutive IBG were studied. Intraoperatively, the following measurements were performed: distal pulse palpation (DPP), continuous wave Doppler (CWD), pulse volume recording (PVR), and ultrasonic volume flowmetry (UVF), followed by intraoperative angiography of the entire graft and runoff vessels. The outflow resistance was graded according to the guidelines of the Society for Vascular Surgery and International Society for Cardiovascular Surgery (SVS/ISCVS runoff score). Graft patency was determined noninvasively (PVR, colour Duplex) up to 12 months following surgery. Predictive values and likelihood ratios for the intraoperative tests in detecting a technical problem during the bypass procedure and in predicting early graft failure were calculated. RESULTS: There were five immediate revisions for problems detected intraoperatively. Angiography did not identify any additional problems but assisted in the correct location of the problems detected by the other tests. DPP and CWD were highly significant indicators of the need for revision with likelihood ratios for a positive test of 14.7 (p < 0.01) and 12.3 (p < 0.01) respectively. PVR did not achieve statistical significance in this respect. None of the intraoperative tests was a statistically significant predictor of early graft failure. The SVS/ISCVS runoff score, on the other hand, predicted early failure with a PPV of 33% (likelihood ratio for a positive test of 4.9, p < 0.05). None of the grafts with a perfect SVS/ISCVS runoff score (n = 39) failed in the first postoperative month. CONCLUSIONS: Simple CWD insonation of graft and anastomoses is the best intraoperative indicator for technical inadequacies after IBG. Routine intraoperative angiography is not necessary and intraoperative anatomical imaging may be reserved for situations in which noninvasive documentation of technical success is absent. Contrary to the intraoperative haemodynamic test results, the SVS/ISCVS runoff score is a good predictor of early graft failure.

Adult↗
PubMed1994

Cloning and expression in murine erythroleukemia cells: the soluble forms of the type I and type II tumor necrosis factor receptors fused to an immunogenic affinity tag.

We have cloned, expressed, and purified the extracellular domains of types I and II human tumor necrosis factor receptors. Both proteins were expressed in and secreted by murine erythroleukemia cells under the control of the human beta-globin promoter placed down-stream from the human globin locus control region. Secretion of both proteins was directed by the respective tumor necrosis factor receptor signal sequence. Each tumor necrosis factor receptor extracellular domain was expressed as a chimeric protein, fused to a carboxy terminal flexible peptide linker and an antigenic affinity tag. Secretion of both proteins into the growth medium in a hollow fiber bioreactor was achieved. A monoclonal antibody generated against the affinity tag allowed the purification of both proteins. These were isolated as biologically active products in that they bound human tumor necrosis factor-alpha in a 125I-radioiodinated ligand binding assay. The two proteins also bound tumor necrosis factor-alpha at approximately equimolar ratios as demonstrated by BIAcore sensorgram analysis.

Affinity Labels↗
PubMed1994

A compliant tubular device to study the influences of wall strain and fluid shear stress on cells of the vascular wall.

PURPOSE: Cellular constituents of the blood vessel wall are continuously subjected, in vivo, to both mechanical and hemodynamic forces, which elicit structural and biologic responses. We have developed a compliant tubular system, the vascular simulating device (VSD), that reproduces these forces, while supporting the attachment and the experimental manipulation of endothelial and smooth muscle cells. METHODS: The VSD consists of a compliant silicone rubber tube coupled to a pump system, which permits the simultaneous application of known levels of pressure and flow, to vascular wall cells cultured on the inner surface of the tube. Seeded cells can be monitored visually under phase contrast or fluorescent optics, as well as harvested and analyzed for biologic responses. RESULTS: The elastic modulus and compliance of the silicone rubber tube are similar to those of canine and human arteries. Endothelial and smooth muscle cells cultured on the lumenal surface of the tubes remain attached and viable after subjecting them to physiologic pulsatile flow and cyclic strain. CONCLUSION: The VSD makes it possible to approximate, in vitro, those forces encountered by vascular wall cells, in vivo and therefore may make it possible to determine whether specific combinations of mechanical and hemodynamic forces are causally associated with specific vascular diseases.

Animals↗
PubMed1994

The durability of different reconstructive techniques for atherosclerotic renal artery disease.

PURPOSE: Among various surgical techniques for renal artery reconstruction (RAR), anatomic aortorenal bypass has been the preferred standard. Yet concern regarding origin of the bypass from a diseased aorta and desire to avoid a major aortic operation in these patients who are often at poor risk has led to increasing use of extraanatomic bypass grafting, particularly hepatorenal and splenorenal bypass. This study was conducted to compare the safety and long-term performance of these different techniques of renal artery reconstruction. METHODS: We reviewed a 15-year (1976 to 1991) experience with 323 surgical RAR performed in 285 patients with atherosclerotic renovascular disease. Long-term patency and survival rates were analyzed by life-table methods. Variables potentially affecting early failure of the RAR and perioperative and late mortality rates were examined by Cox proportional hazards models. RESULTS: Diffuse atherosclerosis characterized the patients' clinical profile. Clinically evident coronary artery disease was present in 54% of patients, and some degree of renal insufficiency was present in 60%. Ninety-five percent of patients had hypertension with poor control of hypertension seen in 50%. Aortic disease necessitated combined aortic grafting and RAR in 43% of the study group. Various techniques of RAR were used as follows: endarterectomy or patch angioplasty, 8.5%; extraanatomic bypass grafting, 37% (hepatorenal, 62; splenorenal, 52; iliorenal, 7); and aortorenal bypass grafting, 54% (native aorta, 34; combined aortic graft and RAR, 140). Early failure of the RAR occurred in 5% of cases, and the operative mortality rate for the entire cohort was 5.6%. Median follow-up duration was 9.4 years. A comparison of early and late patency for the major types of RAR revealed equivalent (p = 0.44) performance of aortorenal and extraanatomic bypass grafting. Perioperative complications occurred more frequently (p < 0.02) in patients undergoing combined operations. The cumulative 5-year survival rate for all patients was 75%. CONCLUSIONS: Because extraanatomic bypass grafting can provide long-term results equivalent to aortorenal bypass grafting, the choice among techniques for RAR in patients with diffuse atherosclerosis should be based on both technical and operative safety considerations, rather than adherence to aortorenal bypass grafting as an inherently superior technique.

Aged↗
PubMed1994

Presentation and patterns of aortic aneurysms in young patients.

PURPOSE: Although aortic aneurysm (AA) is primarily a disease of older age groups, younger (< 51 years) patients infrequently are admitted requiring AA surgery. We sought to compare the characteristics of these patients with those of a randomly selected group of older patients with AA. METHODS: We identified 26 patients with AA (group I) under age 51 (mean age 44.8) treated surgically between 1977 and 1993, after excluding patients with acute aortic dissection, traumatic pseudoaneurysms, and ascending or arch aneurysms, and compared them with 75 randomly selected patients with AA between the ages of 65 and 75 (mean age 70.3) who were surgically treated during the same time period (group II). RESULTS: Prevalence of hypertension, diabetes, coexisting heart, kidney, or occlusive peripheral vascular disease was similar between the two groups, and familial aneurysm rates and sex distribution did not differ significantly. More patients in group I had symptoms at the time of presentation (46% vs 6.7%, p < 0.001), and they also had larger AAs (6.9 cm vs 6.0 cm, p = 0.01). Definable causes of aneurysmal disease, such as Takayasu's, Cogan's, and Marfan syndromes, were more common among the young patients (23% vs 0%, p = 0.01), but most (77%) young patients did not have an identifiable syndrome associated with their aneurysm disease. Group I had a marked shift toward proximal aneurysms, defined as involvement of juxtarenal, suprarenal, or thoracoabdominal aorta (46% vs 18% in group II, p < 0.01). This difference persisted even when aneurysms associated with the above syndromes were excluded from consideration (p = 0.02). Cigarette smoking was much more common among the young patients (83% vs 51% in group II, p < 0.01). Smoking in group II was associated with more extensive aneurysm disease (p = 0.04). CONCLUSIONS: Aneurysmal disease presenting in the young adult is more likely to be symptomatic and associated with more proximal aortic involvement than aneurysmal disease in older patients. Smoking appears to play an important role in the pathogenesis of aneurysmal disease in the young patient and was associated in our study with more proximal aneurysms among older patients. A subgroup of patients at risk for early and aggressive aneurysm disease is suggested by these data.

Adult↗
PubMed1994

Photodynamic therapy inhibition of experimental intimal hyperplasia: acute and chronic effects.

PURPOSE: Intimal hyperplasia (IH) is a focal arterial problem that still eludes successful therapy. We have previously demonstrated the feasibility of use of photodynamic therapy (PDT) for the acute treatment of experimental IH with light to activate an otherwise biologically inert photosensitizer. The purpose of this study was to determine the acute and long-term effects of PDT inhibition of IH on the artery wall. METHODS: Segmental IH was induced by balloon injury localized to the cervical common carotid artery of 33 rats. The photosensitizer chloroaluminum sulfonated phthalocyanine (5 mg/kg) for the experimental group or saline solution for the control group was administered intravenously. Twenty-four hours later, all instrumented portions of arteries were irradiated at 675 nm to induce cytotoxic injury in the PDT-treated arteries as compared with laser only-treated arteries for controls. Animals were killed at 1, 2, 4, and 16 weeks. RESULTS: There were no untoward side effects in either group. All PDT-treated arteries were devoid of smooth muscle or inflammatory cells in the treated media. There was no evidence of arterial degeneration of PDT-treated arteries. Only three arteries in the PDT group developed IH, whereas it was universal in all controls. In control arteries, immunocytochemistry with bromodeoxyuridine revealed maximal intimal and medial cell proliferation at 1 week, and morphometric analysis demonstrated a maximal IH at 2 weeks. Immunocytochemistry staining for smooth muscle cell actin was positive for the IH in control and when present in PDT-treated arteries, whereas the adventitia of PDT-treated arteries were positive after 2 weeks. Electron microscopy demonstrated early myofibroblast migration to the adventitia, and at 16 weeks occasional myofibroblasts were noted in the media of PDT-treated arteries. There was complete reendothelial cell covering of the intima by 4 weeks. CONCLUSIONS: These in vivo data demonstrate that PDT is an effective local method for the treatment of experimental IH. There is no evidence of significant recurrence of IH or arterial degeneration. Further studies with PDT may provide novel approaches to the understanding and treatment of arterial IH.

Animals↗
PubMed1994

Carotid endarterectomy for unstable and compelling neurologic conditions: do results justify an aggressive approach?

PURPOSE: In a retrospective study the outcome of 70 carotid endarterectomies (CEA) in 68 patients with neurologically unstable conditions or anatomically compelling findings on carotid angiography was examined to more accurately identify patients who might benefit from CEA in this setting. METHODS: Out of a total of 1734 CEAs performed from 1978 to 1992, five groups of patients were selected: group A, stroke in evolution with tight stenosis (n = 5); group C, crescendo transient ischemic attacks (CTIA) continuing despite heparin (n = 14); group D, CTIA (above criteria) ceasing with heparin (n = 21); and group E, anatomically compelling situation on carotid angiography (n = 13). Data collected included preoperative and postoperative Neurologic Event Severity Score (NESS), CHAT classification, arteriosclerosis risk factors, demographics, and long-term overall and transient ischemic attack/stroke-free survival rates. RESULTS: Risk factors and demographics were similar in all groups. By NESS criteria the conditions of 97.3% of patients in the neurologically unstable groups A to C were improved or stabilized after operation, with one deterioration (2.7%). All patients in group B either stabilized or improved. In group D, one patient's NESS deteriorated, resulting in 3.5% overall morbidity rate and no deaths for groups A to D. Follow-up showed an overall survival rate by Kaplan-Meier analysis equivalent to a matched control population, with 85% alive at 5 years. The cumulative TIA/stroke-free survival rate at 5 years was 75%. CONCLUSIONS: In this retrospective series, CEA performed for compelling or unstable neurologic findings carried low morbidity and mortality rates. Early aggressive surgical therapy of neurologically unstable patients may be warranted because our results improved on the anticipated natural history of the conditions studied. Further clarification of proper patient selection is necessary before this principle can be applied broadly.

Adult↗
PubMed1994

Arterial geometric abnormalities produce two-dimensional compliance disturbances.

PURPOSE: This study describes the two-dimensional compliance changes that develop in low-grade hemodynamically insignificant stenoses. METHODS: Twenty-four male Sprague-Dawley rats were used in the study. In 14 rats, balloon injury and endothelial denudation of the common carotid artery was followed by the application of a ligature, which produced a 20% narrowing of the outer diameter; five other rats were similarly injured without creating a stenosis, and five were stenosed without injury. The latter two groups served as control. Two-dimensional measures of arterial wall motions were obtained 30 minutes and 3 days after surgery by use of a video motion analyzer. Subsequently, circumferential (Cc) and longitudinal (Cl) compliance values were calculated and analyzed. RESULTS: At 30 minutes, in the injured stenosed arteries, overall Cc was significantly greater than in the nonstenosed injured arteries at all measured points along the artery. Both stenosed injured and stenosed noninjured arteries also displayed increased Cc both proximal and distal to the stenoses compared with Cc values furthest from the stenosis. Cl values in the stenosed arteries, both injured and noninjured, became negative across the stenosis. All two-dimensional compliance changes occurred within the area of arterial narrowing and gradually resolved approaching the nonstenotic region of the artery. At systole, in the adjacent to the stenosis arterial segments, circumferential distension was accompanied by simultaneous longitudinal compression. Three days after surgery, although Cc increased proximal and distal to the stenosis and Cl decreased in the areas adjacent to the stenoses, no statistically significant difference was found. CONCLUSIONS: Low-grade stenosis results in a longitudinal compression accompanied by a relatively increased circumferential distension of arterial segments adjacent to the stenotic region. This pattern is not initiated or influenced by the presence or absence of endothelial cells.

Animals↗
PubMed1994

Biaxial elastic properties of rat arteries in vivo: influence of vascular wall cells on anisotropy.

There is no consensus as to the degree of arterial anisotropy or to its relationship to vascular cell function. Given the relevance of the isotropic assumption in formulating elasticity models, reliable measures of biaxial displacements are needed. In this study, a video motion analyzer (VMA) was used to describe the biaxial in vivo dynamic elasticity of 22 carotid arteries and 5 abdominal aortas in 27 rats. The influence of vascular cell function was also examined by subjecting six rats to a photosensitive drug, chloroaluminum sulfonated phthalocyanine (CASPc), which is focally cytotoxic on activation by laser. Circumferential compliance (Ccirc) was greater than longitudinal compliance (Clong) for all vessels. Compliance pressure curves were nonlinear, and biaxial displacements were in phase. The circumferential elastic modulus was less than the longitudinal modulus at common stresses. CASPc + laser reduced Ccirc but not Clong, thus altering Poisson's ratio. In conclusion, rat arteries are biaxially, nonlinearly elastic and anisotropic in vivo. Vascular cells modulate Poisson's ratio by influencing Ccirc.

Animals↗
PubMed1993

Claudication in the setting of plethysmographic criteria for resting ischemia: is surgery justified?

Objective noninvasive criteria for resting ischemia are sometimes found in patients with milder clinical complaints. If noninvasive information can predict irrevocable progression to resting ischemia, instances of tissue loss theoretically could be prevented by early intervention. Accordingly, we investigated the clinical outcome in 51 claudicators with pulse volume recorder and/or ankle-brachial index (ABI) criteria for ischemia at rest. Patients with type IV (markedly blunted) or type V (flat) ankle or transmetatarsal pulse volume recordings and/or ABI < 0.5 and accompanying claudication were identified. Resting ischemia and/or tissue necrosis developed in 29% of patients and necessitated vascular reconstruction within 36 months. One patient had a primary above-knee amputation at a different institution and 14 patients underwent successful revascularization. In 3 of 14 patients, reconstruction was accompanied by digit or transmetatarsal amputation. No limbs were lost in the revascularized group. Noninvasive criteria for resting ischemia in patients with claudication alone portend a high rate of progression to resting ischemic symptoms. At present the use of clinical criteria and careful follow-up would permit a high rate of foot and limb salvage in those whose ischemia progresses and would prevent unnecessary surgery in the remaining patients. Further prospective definition of patients at risk for progression of ischemia might help prevent tissue loss in selected patients.

Aged↗
PubMed1993

Familial carotid body tumors: incidence and implications.

Carotid body tumors may occur sporadically (90%) or in a familial pattern (10%). One third of the patients with familial disease have bilateral tumors. We report the case of a patient with bilateral carotid body tumors and a strong family history of such tumors. Details of his evaluation and treatment are reviewed. Relatives of patients with carotid body tumors should be examined carefully, and any suspicious neck mass should be appropriately investigated.

Carotid Arteries↗
PubMed1993

Abnormal wall strain at distal end-to-side anastomoses.

Cyclic stretch has been demonstrated to induce proliferative and secretory activities by cultured arterial endothelial and smooth muscle cells, cellular processes that contribute to the development of intimal hyperplasia. A model of an end-to-side anastomosis was developed to examine the hypothesis that regions of the artery at such anastomoses are subjected to focally increased cyclic stretch, which may stimulate the development of intimal hyperplasia. Polytetrafluoroethylene grafts were anastomosed end to side to latex rubber tubes that have elastic properties similar to those of the human femoral artery. Pulse waves with physiologic pressure, rate, and contour were applied, and systolic and diastolic diameters were measured in two planes at longitudinal intervals. Circumferential strain imposed on the latex "artery" was calculated at each interval. Strain imposed perpendicular to the suture line was also measured. Circumferential strain was consistently maximal at a distinct region of the "artery" along the proximal third of the anastomosis (6.0 +/- 1.1% vs. 3.3 +/- 0.5% at other regions of the "artery"). The maximal strain across the suture line was found at precisely the same region (3.9 +/- 0.3% vs. 2.0 +/- 0.4%). The anastomotic region of the recipient artery in a distal end-to-side anastomosis is subjected to cyclic circumferential strains two times greater than those experienced by the remainder of the artery. This corresponds to a common location of intimal hyperplasia. Such strains may be a stimulus for intimal hyperplasia.

Anastomosis, Surgical↗