Biomedical subjects
Publications and source records attributed to R B Rutherford.
The ideal vascular graft has not yet been developed. However, in the aortic position, excellent results can be obtained using a variety of currently available grafts, which offer similar patency rates and durability. Therefore, graft selection depends on other considerations, such as the ease of handling and preclotting requirements.
The keys to a better outcome in the management of ruptured aneurysm are early diagnosis, aggressive resuscitation, and early operation, with prompt achievement of proximal control. Having achieved these goals, there is a tendency to let down one's guard and relax; indeed, the principles of aneurysm repair beyond this point are similar to those of elective surgery. However, it should be remembered that nearly every complication is more likely in emergency than in elective operations. Therefore, even more care needs to be taken with the technical details at this point to avoid the complications discussed in the following article. The perioperative management must continue at the same heightened level to combat acidosis, hypothermia, coagulation disorders, cardiac dysfunction, fluid overload with pulmonary edema, renal failure, and other common sequelae of this challenging undertaking.
Effective methods for performing abdominal aortic aneurysmectomy associated with congenital pelvic kidney are presented. The embryology and surgical anatomy of these lesions are reviewed. Ordinarily, successful aortic reconstruction can be performed with low risk to the pelvic kidney by use of readily available in situ cold perfusion. Two illustrative case reports applying this method are presented. The recently reported technique of double proximal clamping of the aorta was also employed in one case. This technique allows lumbar collaterals within the aneurysm to perfuse the kidney during construction of the proximal aortic anastomosis, thereby minimizing absolute renal ischemic time. Both in situ cold perfusion and double proximal clamping are effective methods for renal preservation that do not rely on complex extraanatomic techniques. A review of the literature with a discussion of the advantages and disadvantages of previously reported methods of renal preservation is presented.
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Fibroblasts of the periodontium may be involved in extracellular matrix degradation in response to inflammatory cytokines produced by mononuclear phagocytes. Interleukin 1 (IL1), one of these biologically-active agents, is produced by such cells when stimulated by lipopolysaccharide (LPS). Periodontal-ligament (PLF) and gingival fibroblasts responded to recombinant human IL1 beta and to media conditioned by LPS-stimulated mononuclear phagocytes by secreting prostaglandin E (PGE). This response was dose- and time-dependent. Stimulated gingival fibroblasts also produced about five- to ten-fold as much collagenolytic activity when compared to controls but PLF produced no more activity. On mixing the conditioned media from both fibroblast types, inhibitory activity was found in the PLF-culture medium. Thus gingival fibroblasts in particular may be involved in the pathogenesis of periodontal disease by responding to factors produced by inflammatory phagocytes.
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Diagnostic evaluation of patients with possible vascular injuries presents the physician with a number of circumstantial impediments that may limit the applicability of clinical signs and symptoms, noninvasive testing, and angiography. The challenge is to know these limitations and learn to work around them while still applying clinical skills, noninvasive tests, and angiography when appropriate and feasible and to the limits of their worth, rather than to resort to either routine angiography or blind exploration in every case.
Congenital vascular malformations (CVMs) of the limb include simple and cavernous hemangiomas, microarteriovenous and macroarteriovenous fistulas, venous angiomas, and mixed CVMs. In differentiating these lesions, Doppler waveform analysis, labeled microsphere studies, arteriography, closed-space phlebography, and contrast-enhanced CT scans have all been advocated, but each has significant limitations. This article evaluates the ability of magnetic resonance imaging (MRI) in characterizing CVMs. Limb CVMs were evaluated by MRI in eight patients: four in the upper and four in the lower extremity. Before MRI, seven of the patients had arteriography, five had phlebography, and five had Doppler waveform analysis. MRI showed a highly cellular network with little arteriovenous flow in five patients. In four of these, arteriography and phlebography confirmed the presence of a predominantly venous or microfistulous anomaly. In the other three patients, MRI demonstrated high-flow arterial and venous channels and were confirmed by arteriography to have macrofistulous arteriovenous malformations. In all eight patients, MRI revealed the anatomic location and the longitudinal and transverse extent of the vascular malformation as well as their relationships with contiguous muscle groups, bones, and vessels. We conclude that CVMs of the limbs can be characterized accurately with MRI, with the anatomic extent, degree of cellularity, and flow characteristics readily gauged. Because MRI provides the same basic information supplied by angiography and the noninvasive laboratory and assesses anatomic extent and cellularity, it serves well as the primary diagnostic test for suspected CVMs, particularly in infants and children in whom competitive tests pose additional limitations.
Aortobifemoral bypass (ABF) is the preferred operation for patients with bilateral aortoiliac occlusive disease, but for those with unilateral occlusion without significant stenosis of the contralateral iliac artery, alternative reconstructions, such as femorofemoral (FF) or iliofemoral (IF) bypass have been advocated. We compared the surgical outcome in 96 such patients after ABF (n = 32), FF (n = 47), or IF (n = 17) bypasses, with biplane arteriography and noninvasive laboratory testing used to assess the contralateral iliac artery and runoff status, in particular, patency of the superficial femoral artery (SFA). Graft patencies were assessed by noninvasive criteria and analyzed by the life-table method. The only death occurred after ABF bypass (3.1%). Primary patency rates at 1, 3, and 5 years with an open SFA were 100%, 89% and 89%, respectively, for ABF; 92%, 92%, and 92% for FF; and 71%, 71%, and 36% for IF. When the SFA was occluded, the primary patency rates at 1, 3, and 5 years were 100%, 100%, and 72%, respectively, for ABF; 72%, 53%, and 35% for FF; and 56%, 56%, and 56% for IF bypasses. There were no later occlusions on the contralateral ("good") side after ABF. Significant progression of atherosclerosis in donor iliac artery was observed in 6% of both FF and IF bypasses. We conclude that ABF is the preferred operation for extensive iliac artery occlusive disease that is hemodynamically significant only on the symptomatic side unless specifically contraindicated by prohibitive risk or abdominal disease. This is particularly true in the face of SFA occlusion.
The evaluation of clinical reports on vascular disease is often made difficult by variations in descriptive terms, clinical classification, and outcome criteria. In 1983 the Joint Council of the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery created the Ad Hoc Committee on Reporting Standards to address these problems and recommend solutions. Some general problems were addressed in the initial report dealing with lower extremity ischemia. This article concerns clinical standards for reports dealing with cerebrovascular disease, suggests a scheme for clinical classification, and recommends standardized reporting practices for grading risk factors, angiographic and other diagnostic findings, and the results and complications of therapeutic intervention.
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Two hundred forty-nine well-characterized difficult distal bypasses, entered into a multicenter dextran 40 trial, were reevaluated after 3 years. Seventy in situ (IS) vein grafts, 49 reversed saphenous (RS) vein grafts, 60 polytetrafluoroethylene (PTFE) grafts, and 70 umbilical vein (UV) grafts were used. Primary and secondary patency rates at 3 years were, respectively, 84% and 90% for IS, 66% and 73% for RS, 35% and 48% for PTFE, and 24% and 32% for UV. Subgroup analysis according to the site of distal anastomosis showed no significant differences in primary patency among these grafts at the above-knee level but significant differences between both vein grafts (IS and RV) and the others (PTFE and UV) below the knee (78% vs 31%, respectively). This difference increased at the tibial level (78% vs 10%) but there was also a significant difference between IS grafts (88%) and RS grafts (63%) at this level. Hazard functional analysis showed all grafts except IS grafts begin to fail at an increasing rate again by 24 months. Although overall results appeared to favor PTFE over UV, 62% of PTFE vs 16% of UV terminated at the above-knee level and the patency results of these two grafts were not significantly different at any level. The only other factor than graft type and distal anastomotic site that consistently correlated with late patency was tobacco use. Diabetic patients actually fared significantly better than nondiabetic patients, presumably because of the higher use of IS grafts and lower use of tobacco. The choice of graft overshadows all other factors affecting patency and its influence is magnified with more distal terminal anastomosis.
Because clinical assessment of bowel viability is unreliable, other methods of determining intestinal perfusion have been recommended. Since none of these quantifies intestinal blood flow, we measured flow at the detection thresholds of Doppler ultrasound, photoplethysmography, and intravenously administered fluorescein, perfused the intestines at these threshold levels, and assessed histologic evidence of ischemic damage. The intestines of five anesthetized dogs were perfused for 4 hours via an in-line pulsatile extra-corporeal circuit assembled between the iliac and superior mesenteric arteries at either relatively physiologic (approximately 20 ml/min/kg body weight) levels or reduced levels representing the flow detection thresholds of Doppler ultrasound or photoplethysmographic probes (approximately 4 ml/min/kg). Intravenously administered fluorescein was detected at even lower perfusion levels (approximately 2.1 ml/min/kg). Clear-cut ischemic changes were documented histologically in all subjects perfused at Doppler/PPG flow detection thresholds but in none of those perfused at normal levels. We conclude that threshold blood flow detection by any one of these methods, especially fluorescein, occurs at levels inadequate to guarantee tissue viability.
Adolescent depression represents a growing concern for secondary school personnel. Depression is often related to suicide, which currently ranks as the second leading cause of death in adolescents. Since secondary school personnel should be able to identify characteristics of adolescent depression, the purpose of this study was to assess regular classroom teachers', guidance counselors', and special education teachers' ability to identify characteristics of adolescent depression. Results indicated that counselors possess the greatest knowledge of these characteristics, while regular and special education teachers are somewhat less able to identify them. Results are discussed in terms of training and evaluation issues for teachers.
C3b or lipopolysaccharide treatment of human peripheral blood monocytes in culture stimulates an early release of thromboxane B2 and a delayed release of prostaglandin E into culture supernatants. Immunoreactive thromboxane B2 release is maximal from 2-8 h, whereas prostaglandin E release is maximal from 16-24 h after stimulation of monocytes in culture. We further examined this process by comparing the time course of labelled prostaglandin E2, prostaglandin E1 and thromboxane B2 release from human monocytes which were pulse or continuously labelled with [3H]arachidonic acid and [14C]eicosatrienoic acid. The release of labelled eicosanoids was compared with the release of immunoreactive prostaglandin E and thromboxane B2. The time course of prostaglandin E2 release was virtually identical to the release of prostaglandin E1 in all culture supernatants regardless of labelling conditions. However, release of immunoreactive prostaglandin E paralleled the release of labelled prostaglandin E1 and E2 only for continuously labelled cultures. The release of labelled prostaglandin E1 and E2 from pulse labelled cultures paralleled the release of thromboxane B2 and not immunoreactive prostaglandin. In contrast, labelled and immunoreactive thromboxane B2, quantitated in the same culture supernatants, demonstrated similar release patterns regardless of labelling conditions. These findings indicate that the differential pattern of prostaglandin E and thromboxane B2 release from human monocytes is not related to a time-dependent shift in the release of prostaglandin E1 relative to prostaglandin E2. Because thromboxane B2 and prostaglandin E2 are produced through cyclooxygenase mediated conversion of arachidonic acid, these results further suggest that prostaglandin E2 and thromboxane B2 are independently metabolized in human monocyte populations.
Fiberoptic angioscopy was performed with 2.5- and 3.3-mm angioscopes in 25 arteries and grafts in 19 patients. Radiologically normal and abnormal arteries and anastomotic sites were examined. All vessels and grafts were visualized and images of normal arterial wall, subclinical and obstructing atherosclerotic plaque, and suture lines were defined. Unexpected endovascular findings were noted in five patients (26%) and included large amounts of free-floating clot (one patient), atherosclerotic debris (two patients), and membranelike obstructions (two patients). Angioscopy required three to ten minutes and resulted in no complications. Experience with the flexible angioscope indicates that satisfactory visualization and specific recognition of angiographically unsuspected problems can be obtained. The flexible angioscope is faster and appears more etiologically specific than arteriography.
Acute intestinal ischemia and infarction remain serious clinical problems despite early operative intervention. An accurate and reproducible method of assessing ischemic tissue is critical to determine the precise limits of resection. The purpose of this study was to compare the utility of infrared photoplethysmography, intravenous fluorescein, and Doppler ultrasound in assessing intestinal ischemia in an operative canine model. After five segmental mesenteric arterial ligations in each of six conditioned dogs, the detection threshold for the limits of arterial perfusion of each modality was determined and correlated with the respective histopathologic specimens. Infrared photoplethysmography proved to be 100% sensitive for ischemia when its waveform amplitudes were 50% or greater of matched reference waveforms, whereas both intravenous fluorescein and Doppler ultrasound were 88% sensitive. All were comparably specific. We conclude that infrared photoplethysmography is comparable to intravenous fluorescein and Doppler ultrasound in the assessment of ischemic intestinal segments.