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Biomedical subjects

W M Abbott

Publications and source records attributed to W M Abbott.

At least 127 records · Page 7Linked to original sources
PubMed1987

Continuous monitoring of oxygen tension with a transcutaneous sensor during hypotensive anesthesia.

Transcutaneous oxygen tension (TCPO2) is a useful noninvasive technique for monitoring arterial oxygen tension under stable circulatory conditions. This study was undertaken to determine if TCPO2 is also reliable during sodium nitroprusside-induced hypotension under general anesthesia. Arterial blood gases and TCPO2 were measured prior to inducing hypotension (baseline), at 20-min intervals during hypotension, and when systemic arterial pressure had returned to within 10% of the control (pre-hypotension) value. With induced hypotension, PaO2 and TCPO2 decreased significantly (P less than 0.05), and were well correlated by linear regression (r greater than 0.85); however, regressions were strongly dependent on the individual patient. The mean regression line for all patients as a group was given by TCPO2 = 0.69 PaO2 + 20.7 mmHg (r = 0.93, P less than 0.01); significantly different regressions were obtained for each patient (P less than 0.0001). Comparing changes in TCPO2 versus those in PaO2 (relative change from baseline values) did not substantially reduce the variability among patients. It is concluded that TCPO2 reliably reflects changes in arterial oxygen tension during controlled hypotension under general anesthesia, but that a separate calibration of TCPO2 vs. PaO2, obtained prior to inducing hypotension, may be required for each individual patient.

Adult↗
PubMed1987

Extending the limits of limb salvage.

Over the past several years a combination of diverse steps has culminated in a significant improvement in our ability to save ischemic extremities. Encompassing all phases of vascular surgery, these advances in diagnosis, therapy, and long-term management are outlined. These and future improvements hold promise for extended limb salvage with lower mortality than previously considered possible.

Angioplasty, Balloon↗
PubMed1987

Effect of compliance mismatch on vascular graft patency.

The hypothesis that a mismatch in compliance between a vascular graft and its host artery is detrimental to graft patency was tested by implanting paired arterial autografts, prepared with differential glutaraldehyde fixation of carotid arteries in the femoral arteries of dogs. These grafts differed only in circumferential compliance: they were 100% (compliant) vs. 40% (stiff) as compliant as the host artery. Their flow surfaces were equivalent, as determined by physicochemical measurements and scanning electron microscopy; both lacked viable cells, as determined by in vitro cell culture. In 14 dogs, eight stiff and two compliant grafts became occluded within 3 months, the latter doing so within 24 hours after their contralateral counterparts. Cumulative patencies were 85% and 37% for compliant and stiff grafts, respectively (p less than 0.05) and 100% and 43%, excluding the two dogs with bilateral graft failures (p less than 0.01). We conclude that even with near optimal flow surfaces, compliance mismatch is deleterious to graft patency.

Animals↗
PubMed1986

Attempts to obtain anti(D2 dopamine receptor) antibodies via the anti-idiotypic route.

Five stable hybridomas have been obtained that secrete monoclonal antibodies against the D2-dopamine receptor-selective drug spiperone. Each monoclonal antibody has been characterized in terms of its ability to bind a range of dopamine-receptor-selective ligands. One monoclonal antibody has been purified by Protein A affinity chromatography and used to immunize mice. Anti-idiotypic antisera and one hybridoma secreting an anti-idiotypic monoclonal antibody were obtained and shown to inhibit [3H]spiperone binding to the anti-spiperone antibody used for immunization. Neither the antisera nor the anti-idiotypic monoclonal antibody, however, inhibited binding of [3H]spiperone to D2-dopamine receptors.

Animals↗
PubMed1986

Compliance changes in glutaraldehyde-treated arteries.

Glutaraldehyde tanning of carotid arteries was used to develop a model for studying the effects of compliance on arterial graft performance, independent of other graft parameters. Canine carotid segments were filled with dilute phosphate-buffered glutaraldehyde (0-0.5%, pH 7.4), maintained at physiological pressure, and then immersed in either saline or 10.0% glutaraldehyde for up to 1 hr. After rinsing with saline, compliance was measured in vitro. All vessels which were immersed in 10% glutaraldehyde exhibited a significant reduction in compliance compared to native artery control [C = 11.8 +/- 1.3 (mean +/- SEM), % radial change/mm Hg X 10(-2), measured at 100 mm Hg], but maximum stiffness (C = 1.1 +/- 0.3) required that the lumen be specifically exposed to at least 0.025% glutaraldehyde in addition to simple immersion of the vessel segment in 10% fixative. Exposing the artery to 0.5% glutaraldehyde internally, without immersion of the entire structure, caused a decrease in compliance similar to that obtained after immersion in 10% glutaraldehyde, with only saline present in the lumen. Matched pairs of stiff and compliant grafts were generated by exposing the lumen to 0.025% glutaraldehyde and immersing the vessels in 10% fixative or saline, respectively. Light and scanning electron microscopy, internal reflection spectroscopy, and measurements of critical surface tension revealed nearly identical wall morphology and lumenal surface chemistry for these matched pairs. Differential tanning of the internal and external surfaces of carotid arteries thus provides a good model of arterial prostheses, wherein a substantial compliance mismatch can be studied without the complicating influences of varying diameter or differing flow surface properties.

Aldehydes↗
PubMed1986

Use of the splenic and hepatic arteries for renal revascularization.

During a 16-year period at the Massachusetts General Hospital 77 patients underwent 79 procedures (29 hepatorenal bypasses, 50 splenorenal arterial anastomoses) for treatment of renovascular hypertension, renal preservation, or both. The procedure was chosen primarily to avoid a diseased or scarred aorta in 41, to allow a staged approach to bilateral renal artery stenoses or multiple vascular lesions in 17, as a "lesser operation" for five poor-risk patients, for complex problems including trauma, mycotic aneurysm, aortic dissection, thoracoabdominal aneurysm, and renal artery aneurysm in five, and as the procedure of choice in 11 patients. The perioperative mortality rate was 6% for the 77 patients studied. No hepatic dysfunction was seen. Deterioration of renal function occurred on three occasions but only in patients with bilateral simultaneous repair. Cure or improvement of hypertension was achieved in 52 of 63 patients and renal function preserved or improved in 67 of 77 patients. Long-term functional results remain good during follow-up periods up to 14 years. Our experience indicates that use of the hepatic or splenic artery may provide a safe and largely successful alternative for renal revascularization in selected circumstances.

Follow-Up Studies↗
PubMed1986

Suture technique and para-anastomotic compliance.

We previously described a para-anastomotic hypercompliant zone (PHZ), located 3 to 4 mm from end-to-end continuous anastomoses in canine femoral arteries, in which arterial compliance first increases approximately 50% above adjacent reference values before falling to a minimum at the anastomosis. To determine if PHZ is affected by suture technique, 16 interrupted and 21 continuous end-to-end anastomoses were studied. Pulsed ultrasound was used to obtain detailed longitudinal profiles of compliance and diameter vs. distance, at 1 mm intervals within a 2 cm region centered at the anastomoses. Both compliance and diameter at the anastomosis were lower in continuous compared with interrupted anastomoses (p less than 0.003). The PHZ was present in 86% of continuous but in only 50% of interrupted anastomoses (p less than 0.03). The site of peak compliance averaged 3.8 +/- 1.2 mm from the anastomosis and was independent of suture technique. The increase in peak compliance at the PHZ, when normalized to adjacent references values, was the same in continuous and interrupted anastomoses. PHZ augments any preexisting compliance mismatch between artery and graft, which may contribute to the development of para-anastomotic subintimal hyperplasia. Interrupted anastomoses, which create a smaller compliance mismatch than do continuous and have a lower incidence of PHZ, may be preferred in certain settings.

Animals↗
PubMed1986

Noninvasive measurements of nonlinear arterial elasticity.

To describe fully the compliance characteristics of an artery with nonlinear elastic properties, measurements must be obtained over a wide range of pressures. Furthermore, repeated measurements, as required in temporal studies of arterial implants, require that the measuring technique be noninvasive. The application of a pulsed ultrasound echo-tracking device is described, which fulfills both criteria. Nonlinear compliance-pressure (CP) curves were obtained from the femoral arteries of dogs, with the use of halothane anesthesia to vary systemic pressure, and were used to compare the gross elastic properties of different vessels. Studies using controlled hemorrhage or the vasoactive drugs, nitroprusside and levarterenol (norepinephrine), were used to verify that the CP curves obtained during halothane anesthesia did not reflect varying degrees of smooth muscle activation. However, surgical exposure did temporarily reduce arterial compliance at pressures between 60 and 140 mmHg. The effect of vasoactive intervention and of postsurgical changes in arterial or graft compliance can thus be quantitated by use of CP curves or by comparing incremental elastic moduli, which can also be estimated from the noninvasively derived measurements.

Animals↗
PubMed1986

External pneumatic calf compression reduces deep venous thrombosis in patients with ruptured intracranial aneurysms.

We evaluated the ability of intermittent external pneumatic calf compression to prevent deep venous thrombosis after subarachnoid hemorrhage from ruptured intracranial aneurysms. Fifty-six subarachnoid hemorrhage patients not given external pneumatic calf compression were compared with 90 patients who had calf compression after their subarachnoid hemorrhages. Both groups of patients were on strict bedrest for 7 to 21 days after aneurysm rupture, and both received epsilon-aminocaproic acid, 30 to 36 g/day intravenously, until operation. The risk factors in the two groups were similar, and the nursing and medical care did not seem to differ. Of patients without external pneumatic compression, 18% had venographically proven deep venous thrombi, which contrasts with 6% of patients receiving calf compression. This was a significant difference (P less than 0.05; chi 2). These retrospective data suggest that external pneumatic calf compression helps to prevent deep venous thrombosis in patients with subarachnoid hemorrhage when delayed operation, bedrest, and antifibrinolytic agents are used.

Adult↗
PubMed1986

Mural degeneration in the glutaraldehyde-tanned umbilical vein graft: incidence and implications.

After discovering an aneurysm in a glutaraldehyde-tanned umbilical vein (GTUV) graft that resulted in graft thrombosis, we reevaluated all patients from our institution who had GTUV grafts implanted for more than 2 years. Of 60 patients identified, 14 of 15 patients with patent grafts were recalled and had either digital subtraction or standard angiographic studies. Angiographic changes in the grafts were graded on a scale of 0 to 3, from normal (grade 0) to frank aneurysmal degeneration (grade 3). Eight grafts (57%) had frank aneurysmal (grade 3) changes, and three other grafts (21%) had preaneurysmal (grade 2) changes. Only one graft was angiographically normal. GTUV grafts undergo aneurysmal degeneration in a significant percentage of implants. Symptomatic aneurysms have presented with thrombosis and limb-threatening ischemia as well as rupture. GTUV aneurysms should be treated by complete graft resection, as segmental resection of diseased portions of grafts resulted in metachronous aneurysm recurrence. Because of the high incidence of GTUV degeneration, the clinical indications for the use of GTUV grafts should be seriously reevaluated, and we recommend that all patients with patent GTUV grafts for more than 2 years be evaluated for the presence of aneurysmal degeneration.

Aldehydes↗
PubMed1986

Migration of adult human vascular endothelial cells: effect of extracellular matrix proteins.

An ideal vascular prosthetic graft should support rapid endothelial coverage and allow maximal rates of endothelial cell migration on its surface. To study this we modified and developed a method to measure rates of migration of adult human vascular endothelial cells (AHVECs) on test surfaces using an O-ring fence technique. We measured the rates of AHVEC migration on a variety of extracellular matrix proteins of interest because of their ability to support cell attachment. AHVECs, initially constrained in rings with an area of 0.62 cm2 (day 0), were allowed to migrate radially, and area coverage was measured after 7 days. The greatest areas of migration were seen on fibronectin (1.20 cm2) and gelatin (1.29 cm2) when compared with control (polystyrene [0.97 cm2]), p less than 0.01, p less than 0.05. Migration on laminin and prepared extracellular matrix from AHVEC was not statistically different from that of controls. Of extracellular matrix proteins studied in our system, a gelatin substrate in the presence of serum resulted in maximal rates of AHVEC migration.

Blood Vessel Prosthesis↗
PubMed1986

Use of tritiated thymidine as a marker to compare the effects of matrix proteins on adult human vascular endothelial cell attachment: implications for seeding of vascular prostheses.

We have developed a technique to measure attachment of adult human vascular endothelial cells to test surfaces with tritiated thymidine used as a marker. With this technique, we measured attachment of adult human vascular endothelial cells to a series of extracellular matrix proteins, including fibronectin-coated (10 micrograms/cm2), laminin-coated (10 micrograms/cm2), and collagen-coated (1% gelatin) surfaces because of the role of these proteins in promoting cell attachment and growth. For a typical experiment, in the presence of serum, initial attachment (at 1 hour) was greatest on fibronectin-coated (63%) and gelatin-coated (60%) tissue culture plastic (polystyrene) and was least on laminin-coated (28%) or untreated polystyrene (18%). The data suggest that fibronectin, either alone, or with a more complex combination of extracellular components may need to be present on prosthetic surfaces to produce maximal cell attachment and subsequent growth to confluence in vivo. The described method of measuring attachment is independent of surface properties, ensures complete recovery of cells, and will allow systematic exploration of those properties that best support human endothelial cell attachment to vascular prosthetic surfaces.

Blood Vessel Prosthesis↗
PubMed1985

Partial purification of dopamine D2 receptors using lectin affinity columns.

Dopamine D2 receptors, detected by [3H]spiperone binding, were solubilized from bovine caudate nucleus by cholate/sodium chloride and were found to bind to wheat germ agglutinin immobilized on agarose. Specific elution could be achieved with N-acetylglucosamine whereas other sugars tested were inactive in this regard. The eluted preparation was enriched in solubilized receptors about sevenfold. The pharmacological properties of the preparation were essentially unchanged by the lectin affinity purification procedure. The D2 dopamine receptor is therefore a glycoprotein.

Acetylglucosamine↗
PubMed1985

Innominate artery lesions: problems encountered and lessons learned.

Although unusual, innominate artery lesions may present challenging problems. To classify the wide spectrum of problems requiring operation and elucidate certain principles of management, a series of 71 patients undergoing operation for innominate artery problems over a 20-year period was reviewed retrospectively. Occlusive disease (37 patients) was most common, usually presenting with neurologic or ocular symptoms. Other lesions included innominate aneurysm (three), aortic dissection involving the innominate artery (three), traumatic injuries (five), tracheoinnominate fistula (10), anomalous origin or tortuosity causing tracheal compression (six), involvement in mediastinal tumor or scar (six), and thromboembolus (one). The type of operative repair and mortality rate varied with the nature of the lesion. Overall 38 patients underwent transsternal repair, whereas 12 had extrathoracic bypass, 16 resection and oversewing, and five a pexy procedure. For occlusive disease, direct repair via median sternotomy gave best long-term results with an acceptable mortality rate (3.4%). Shunting was not required. Extrathoracic grafting proved safe but less durable and should be reserved for high-risk patients or special circumstances.

Arterial Occlusive Diseases↗
PubMed1985

Selection of patients for preoperative coronary angiography: use of dipyridamole-stress--thallium myocardial imaging.

To identify patients likely to benefit from preoperative coronary angiography, a method utilizing pharmacologically induced coronary vasodilatation in conjunction with serial thallium 201 myocardial perfusion imaging was investigated. Fifty-four patients admitted for elective aortic or femoropopliteal procedures were studied. There were no cardiac ischemic complications in 32 patients with normal scans or persistent defects (scar). In contrast, 7 of 15 patients with thallium redistribution (ischemia) on pre-operative scanning had perioperative ischemic events, including one death and two acute infarcts. An additional seven patients with positive scans (redistribution) underwent coronary angiography prior to vascular surgery; surgically important two- or three-vessel disease was confirmed in all. Dipyridamole-thallium imaging facilitates selection of the subset of truly high-risk patients in whom preoperative coronary angiography may be warranted.

Aged↗
PubMed1985

Endothelial preservation in reversed and in situ autogenous vein grafts. A quantitative experimental study.

The hypothesis that superior endothelial preservation occurs when in situ (as opposed to harvested and reversed) autogenous veins are used as arterial grafts was investigated in a canine model by quantitating endothelial loss as seen on scanning electron micrographs. In situ grafts were compared to atraumatically dissected, nondistended, reversed grafts and to grafts distended to 500 mmHg pressure. Two hours after arterial transplantation, endothelial denudation averaged 3.9 +/- 6.7% on in situ grafts, 18.6 +/- 5.9% on reversed grafts (p less than 0.01), and 35.3 +/- 5.4% on reversed and distended grafts (p less than 0.001). At 24 hours after grafting, a significant increase (p less than 0.01) in endothelial destruction on in situ grafts resulted in a smaller, yet still significant difference in endothelial preservation between in situ and reversed grafts (15.2 +/- 9.5% vs. 25.1 +/- 23.4%, p less than 0.05). Endothelial healing was largely accomplished at 2 weeks regardless of technique. No difference in endothelial fibrinolytic activity could be detected between in situ and gently handled, reversed grafts at 24 hours or 6 weeks after surgery. An obligatory, although modest, degree of endothelial destruction occurred on the undissected portion of in situ grafts as a consequence of exposure to arterial hemodynamics. However, in the immediate postoperative period, endothelial preservation on in situ grafts surpassed that seen in even the most gently handled reversed vein grafts.

Animals↗