Biomedical subjects
Publications and source records attributed to W H Baker.
The superior vena cava was successfully bypassed in a patient with superior vena cava syndrome due to granulomatous mediastinitis. A spiral vein graft constructed from autogenous vein was utilized. Complete relief of symptoms and graft patency documented by venography six months after the operation confirm the usefulness of this procedure in patients with superior vena cava obstruction.
A prospective randomized trial was undertaken to evaluate effects of lumbar sympathectomy as an adjunct to reconstructive surgery of the lower limb. The objective of this study was to assess the early postoperative effect of these procedures on pedal vasomotor tone. A pedal arterial resistance index (PARI) at rest was derived from the ratio of the ankle-digit systolic pressure gradient and pedal blood flow measured plethysmographically. Studies were performed on 32 normal individuals and pre- and postoperatively in 29 patients undergoing aortic reconstruction, 12 of whom were randomly chosen to have lumbar sympathectomy. The mean postoperative PARI in 17 patients who had reconstructions alone was 42+/-7 (S.E.M.) units which approximated the preoperative PARI (43+/-9 units) and normal control values (45+/-6 units). In contrast, 12 patients who had a concomitant lumbar sympathectomy had a significant reduction in the postoperative PARI (8+/-1 units, Pless than 0.005). These initial results indicate that the addition of lumbar sympathectomy to an aortic reconstruction may enhance blood flow to the foot by significantly reducing outflow resistance.
In 119 patients undergoing intra-abdominal arterial reconstructions, the small intestines were retained in plastic bags and the fluid that passed from the small intestine into the intestinal bag was cultured for bacteria to search for enteric organisms as a source of prosthesis infection. No enteric organisms were recovered from these 119 cultures. Three cultures did yield bacterial growth; in two cases Staphylococcus epidermidis was found and in one instance S aureus was cultured. Under the conditions of this study, which included intravenous administration of cephalothin sodium preoperatively, intraoperatively, and postoperatively, the small intestinal transudate did not harbor enteric bacteria.
The records of 206 aneurysmectomy patients over the age of 70 years were reviewed. Increased three- and five-year mortality was seen with a variety of risk factors--cerebral vascular disease, cardiac disease, diastolic hypertension, renal disease, and cigarette smoking--but 30-day mortality was not affected. Age was not a significant risk factor. It is recommended that patients with aneurysms less than 7.5 cm be observed if multiple risk factors are present. Almost all patients with aneurysms greater than 7.5 cm should have resection to prevent death from rupture, although this will be short-term palliation in patients with multiple risk factors.
Fifty carotid endarterectomies were performed in 46 patients with nonhemispheric transient ischemic attacks. There was no mortality. Three patients had temporary strokes postoperatively. Ninety-five percent of the patients were improved and remained so at follow-up examination. Clinical improvement was not related to the presence or absence of vertebral or subclavian stenosis. In retrospect, the two patients who were unimproved had been improperly selected.
The equilibration of cholesterol between plasma and atherosclerotic arteries was studied in 13 patients with obstructive atherosclerosis 2-96 days after the intravenous and/or oral administration of isotopic cholesterol. Arterial specimens were obtained in 12 patients during surgery for arterial reconstruction and in a 13th patient at autopsy. Equilibration was calculated as the specific radioactivity of cholesterol in the arterial tissue relative to that in the plasma (percent).In specimens obtained 2-4 days after pulse labeling, the specific activity of cholesterol in atheroma ranged from 0.3 to 4.5% of that in the plasma. By 17-27 days, the relative specific activity ranged from 6 to 20% in different arteries. In contrast, cholesterol of skeletal muscle had a relative specific activity of 96% by 22 days. By 61-96 days, atheroma cholesterol in the abdominal aorta, common iliac, and femoral arteries had equilibrated to 55, 30, and 26%, respectively. In the patient who died at 96 days, the cholesterol in the coronary arteries had a mean equilibration of 66%, similar to the values for the abdominal (66%) and thoracic (57%) aortas. The route of administration of the isotope did not influence the equilibration. Within the atheromatous plaque, the superficial layers equilibrated better than the deeper layers (75% vs. 22%). The free cholesterol in the atheroma equilibrated to a significantly higher extent than did esterified cholesterol (59% vs. 38%). There was a fourfold higher specific activity of cholesterol in the media than in the corresponding intima (916 vs. 230 dpm/mg). The estimated minimal influx rates of plasma cholesterol into the atheromatous intima ranged from 0.065 to 0.274 mg of cholesterol/g dry tissue per day for different arteries. The approximated turnover times of atheroma cholesterol ranged from 442 days for the abdominal aorta and the coronary arteries to 580 days for the common iliac and 821 and 934 days, respectively, for the femoral and the carotid arteries. These data indicate a definite, though slow, exchange of cholesterol between the plasma and severely atherosclerotic human arteries. Within the atheroma, there are multiple pools of cholesterol, each turning over differently and more slowly than the cholesterol of most other tissues, such as the skeletal muscle. The estimates of influx rate and turnover time of atheroma cholesterol suggest the possibility that this cholesterol is mobilizable, an indication of potential regression of atheromatous lesions in man.
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