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Biomedical subjects

A D Whittemore

Publications and source records attributed to A D Whittemore.

At least 19 recordsLinked to original sources
PubMed1998

Early operative intervention after thrombolytic therapy for primary subclavian vein thrombosis: an effective treatment approach.

PURPOSE: Effective treatment of primary subclavian vein thrombosis focuses on restoration of venous patency, relief of intrinsic stenosis, and decompression of the thoracic inlet. The appropriate method and timing for surgery, however, have not been not well defined. We conducted a study to determine an acceptable treatment approach. METHODS: A retrospective review evaluated 11 patients seen at our institution in an 8-year period. Seven patients were male and four were female, with an average age of 30 years (range 15 to 54 years). Two patients who had symptomatic stenosis without occlusion were omitted from the study. All patients with occlusion received urokinase therapy and underwent surgical decompression within 5 days of thrombolytic therapy. Five percutaneous transluminal angioplasties were attempted before operative intervention. Eleven decompressions were performed, including nine first-rib resections and two scalenectomies. Five operative venous procedures, consisting of thrombectomy with patch closure (n = 3) and bypass (n = 2), and seven venolysis procedures were performed. All patients received coumadin for 3 to 6 months after the operation. RESULTS: Urokinase therapy established wide venous patency in nine of the 11 extremities treated, with the remaining two requiring thrombectomy for residual thrombus at the time of operation. One patient who underwent transluminal angioplasty before the operation had rethrombosis, and the remaining four showed no improvement in venous stenosis after the intervention. Eight of nine extremities treated by first-rib resection and one of two treated by scalenectomy were free of residual symptoms at follow-up. CONCLUSIONS: Preoperative use of percutaneous balloon angioplasty is ineffective and should be avoided in this setting. Surgical intervention within days of thrombolysis obviates the need for interim oral anticoagulation and enables patients to return to normal activity sooner.

Adolescent↗
PubMed1997

Evidence for altered balance between matrix metalloproteinases and their inhibitors in human aortic diseases.

BACKGROUND: Although abdominal aortic aneurysms (AAAs) exhibit increased expression of matrix metalloproteinases (MMPs), the functional balance between MMPs and their tissue inhibitors (TIMPs) remains uncertain. This report compares the proteolytic activity in normal aorta, aorto-occlusive disease (AOD), and AAA by use of a novel in situ zymographic technique. METHODS AND RESULTS: Infrarenal aortic specimens were obtained from 25 patients undergoing surgery for AOD or AAA and were compared with normal aortic tissue (n = 7) obtained from cadavers. Immunohistochemical staining was performed for collagenase (MMP-1), gelatinase A (MMP-2), stromelysin (MMP-3), TIMP-1, and TIMP-2. Net proteolytic activity was determined with in situ zymography whereby aortic sections were incubated on fluorescently labeled substrate. Proteolytic activity was detected under epifluorescent examination. Compared with normal aortic tissue, AOD and AAA tissue demonstrated marked increases in MMP-1 and MMP-3 immunoreactivity, predominantly in the neointima, and modest increases in TIMP-1. MMP-2 was increased in the diseased aortas, and TIMP-2 was abundant in normal, AOD, and AAA samples. Zymography revealed proteolytic activity in AOD and AAA tissues with active digestion of casein and gelatin substrate, particularly on the luminal portion of the specimens. Normal specimens exhibited no lytic activity. Comparison of AOD and AAA specimens revealed no difference in MMP/TIMP immunoreactivity or net proteolytic activity. CONCLUSIONS: MMP expression is markedly increased in AOD and AAA samples, and an imbalance between MMPs and their inhibitors results in similar proteolytic activity. The eventual formation of aneurysmal or occlusive lesions appears not to result from an ongoing difference in the proteolytic pattern.

Aged↗
PubMed1997

Optimal methods for autogenous bypass to the anterior tibial artery.

BACKGROUND: Autogenous bypass to the anterior tibial artery (AT) has been increasingly used for infrageniculate revascularization. The conduit may be routed through the interosseous membrane, a pretibial tunnel, or through a lateral thigh and calf tunnel. This study reviewed results of AT bypass to determine the optimal routing method. METHODS: One hundred thirty consecutive vein grafts to the AT were analyzed retrospectively to compare the experience with the interosseous (group I; n = 50), pretibial (group II; n = 51), and lateral (group III; n = 29) routing alternatives. RESULTS: Indications were claudication in 16 (12.3%) and critical ischemia in 114 (87.8%) procedures with no differences among routing subgroups. Ectopic nonreversed and composite conduits were more common in group III. Major operative morbidity occurred after 7 procedures (5.4%) with no differences in early graft failure (7.7% overall) among the three routing subgroups. Wound infections were more common among group I patients, but without predilection to the interosseous tunnel. During a mean follow-up of 24.9 months (0 to 111.2) overall 5-year secondary patency was 70% with no difference among routing technique. CONCLUSION: Optimal routing choice depends on the location of suitable AT, the length of adequate vein conduit, and the surgeon's preference rather than on factors inherent to the method used.

Aged↗
PubMed1997

Mesenteric revascularization during aneurysmectomy.

The most important association between aortic aneurysm surgery and the mesenteric circulation is the potential for inadvertent compromise to the mesenteric trunks and their end organs. Preservation of visceral blood flow is a critical objective in each case, using methods that have been developed as techniques for suprarenal abdominal and thoracoabdominal aneurysmectomy have evolved. Beyond simply preserving what existed, revascularization by endarterectomy or bypass has a role in selected cases to improve the natural history of advanced mesenteric occlusive disease, although the rationale for such prophylactic surgery must remain relatively weak until more is learned about disease progression in the visceral arteries. Finally, a small number of patients with mesenteric ischemic symptoms at the time of aneurysmectomy clearly benefit from combined surgery.

Aortic Aneurysm, Abdominal↗
PubMed1997

Hemodynamic impact of vein graft stenoses and their prediction in the vascular laboratory.

PURPOSE: We undertook this prospective evaluation to define the direct hemodynamic impact of vein graft stenoses and to correlate intraoperative hemodynamic findings with the preoperative duplex scan. METHODS: Twelve consecutive isolated vein graft stenoses were identified in the vascular laboratory during our routine duplex scanning surveillance protocol over 10 months. Peak systolic flow velocity ratios (PSFVRs; velocity within stenosis/velocity proximal to the stenosis) at the stenoses ranged from 2.7 to 10 (mean, 5.5), and ankle-brachial indexes ranged from 0.47 to 0.94 (mean, 0.68) Preoperative arteriograms were obtained and confirmed the isolated stenoses, which radiographically ranged from 20% to 83% diameter reduction (mean, 64%). At the time of surgery the stenotic graft segment was isolated, and simultaneous pressure measurements proximal and distal to the graft stenosis were measured, along with ultrasound transit-time blood flow measurements. Pressure and flow wave forms were recorded for 10 seconds at 200 Hz and were stored on a personal computer-based digital acquisition system. The graft stenoses were then repaired with either a vein patch or short interposition graft, and the hemodynamic measurements were repeated. Fourier transformation of the pressure and flow curves was performed, and the resistance and longitudinal impedance were calculated for each graft segment. RESULTS: Before repair, mean pressure gradients across the stenotic graft segments (delta P) ranged from 1.0 to 74.6 mm Hg (mean, 20.4 mm Hg), and vein graft flow ranged from 4.9 to 140 ml/min (mean, 45.2 ml/min). After repair of the stenotic segments, the mean pressure gradient was decreased to a mean of 1.3 mm Hg, and vein graft flow increased to a mean of 104.8 ml/min. The PSFVR recorded in the vascular laboratory correlated significantly with delta P (r = 0.71; p = 0.01) and allowed prediction of delta P as: delta P = 7.4 (PSFVR) - 19.8. PSFVR also correlated with measured resistance across the stenosis (r = 0.79; p = 0.004). Conversely, the angiographic measurement of stenosis did not correlate significantly with these parameters. The angiographic measurement of stenosis showed a moderate correlation with the PSFVR (r = 0.58; p = 0.046). CONCLUSIONS: The PSFVR, as measured in the laboratory, is an accurate and useful indicator of the hemodynamic impact of vein graft stenosis. Revision of stenotic vein graft segments resulted in a significant improvement in graft hemodynamics.

Blood Flow Velocity↗
PubMed1997

Validation of a new and specific intraoperative measurement of vein graft resistance.

PURPOSE: Clinical studies have revealed that the most important predictor of successful bypass grafting is the origin and quality of the bypass conduit. Attempts at intraoperative evaluation of the hemodynamic properties of the conduit, including assessment of blood flow (Q), pressure gradients (delta P), and resistance (R), have not been useful. This is because each of these parameters measures the characteristics of the graft plus the outflow bed. To date, no specific measurement of the resistive properties of the conduit only is available. The purpose of this investigation was to evaluate longitudinal impedance (ZL) as a measure of conduit-specific resistance and to evaluate its potential in predicting the outcome of infrainguinal vascular reconstructions. METHODS: ZL was measured during surgery in 73 infrainguinal autologous vein reconstructions performed in 68 patients in two separate institutions over a 21-month period. Vein graft ultrasonic transit time Q and delta P (from proximal to distal anastomosis) were measured at baseline and after maximal peripheral vasodilatation with an intraarterial injection of papaverine 30 mg. Waveforms were recorded for 10 seconds at 200 Hz using a digital acquisition system. R was calculated as proximal mean pressure divided by mean blood flow (Q). After Fourier transformation, ZL was calculated as delta P/Q at each harmonic and total ZL (integral of ZL) was defined as the integral of moduli from 0 to 4 Hz. RESULTS: All hemodynamic variables were significantly affected by papaverine vasodilatation (delta P, 3.9 +/- 0.5 vs 6.3 +/- 0.8 mm Hg; Q, 78.2 +/- 7.0 vs 126 +/- 11 ml/min; R, 134 +/- 17 vs 72.7 +/- 6.2 x 10(3) dyne.sec.cm-5; p < 0.0001), except integral of ZL, which remained constant (31.1 +/- 2.8 vs 30.8 +/- 2.8 x 10(3) dyne.cm-5; p = NS). After follow-up of 1 week to 17 months (median, 5 months), the 1-year primary, primary-assisted, and secondary patency rates were 72% +/- 7%, 77% +/- 6%, and 81% +/- 6%, respectively. Using Cox analysis, primary patency was significantly associated with decreased integral of ZL (p = 0.0001), but not with baseline or papaverine-stimulated delta P, Q, delta P/Q, or R integral of ZL > 47 x 10(3) dyne.cm-5 predicted primary failure with 90% positive and negative predictive value. CONCLUSIONS: Intraoperative measurement of integral of ZL in infrainguinal vein grafts is independent of outflow conditions (that is, does not change with papaverine), and hence describes the resistive properties of the conduit only. In addition, these preliminary data suggest that integral of ZL is predictive of short-term primary patency. integral of ZL is the first available hemodynamic measurement that is conduit-specific and may therefore be a better predictor of graft patency than currently available methods.

Aged↗
PubMed1997

Impact of activated protein C resistance on general vascular surgical patients.

PURPOSE: The prevalence of activated protein C resistance (APCR) and associated thrombotic morbidity among patients who undergo arterial reconstruction were investigated. METHODS: Preoperative assays for functional APCR and factor V (Leiden) mutation were performed on 262 patients who underwent arterial reconstructions that consisted of cerebrovascular surgery (109), aortic or iliofemoral procedures (76), or infrainguinal bypass procedures (77). Patients were monitored for thrombotic complications during the postoperative period. RESULTS: Depending on the stringency of the definition used, functional APCR was detected in 10.6% to 22.0% of patients tested. Factor V (Leiden) was found in 5.3% of patients. Thrombotic morbidity consisting of myocardial infarction, cerebrovascular event, or graft thrombosis occurred in 9.9% of patients, who were followed-up for a mean of 4.8 months. No significant overall correlations were found between APCR and thrombotic morbidity. Subgroup analysis revealed significant associations between functional APCR and total early postoperative thrombotic complications and early graft failure, and between factor V (Leiden) and early cerebrovascular events and late graft thrombosis (p < 0.03). CONCLUSIONS: Functional APCR is somewhat more prevalent among general vascular surgical patients than in the general population, but factor V (Leiden) is no more prevalent. APCR is not a prominent cause of thrombotic morbidity in contemporary vascular surgery. Nonetheless, it is a sufficiently important potential contributor to morbidity among some subgroups to warrant selective testing and directed therapy pending further study.

Factor V↗
PubMed1997

Effects of acetic acid and hydrogen peroxide application during defeathering on the microbiological quality of broiler carcasses prior to evisceration.

The microbiological quality and skin appearance of New York dressed broiler carcasses were determined in two separate experiments after a water control, acetic acid, or H2O2 spray during defeathering. Broilers were picked up from a local processor and transported in coops to the pilot facility. In both experiments, commercial processing parameters were followed up to the defeathering step. After feather removal, the vents of all carcasses were blocked with a cotton plug to prevent contamination of the whole carcass rinse diluent with fecal material from the lower gut. The neck and feet were removed, and the carcasses were placed in individual plastic bags in preparation for a whole carcass rinse. Results showed a statistically significant reduction (P < 0.05) in the log10 total aerobic plate counts for carcasses treated with 1% acetic acid in comparison to the water control (log10 cfu counts = 3.93 and 4.53, respectively). No differences were observed in skin appearance due to the 1% acid treatment. The addition of 0.5, 1, or 1.5% H2O2 to spray waters had no effect on microbiological quality of the carcasses when compared to the water control (4.92, 5.01, 4.91, and 4.99 log10 counts, respectively). The skin of carcasses treated with hydrogen peroxide, regardless of the concentration was bleached and bloated.

Acetic Acid↗
PubMed1997

Relationship between aerobic bacteria, salmonellae and Campylobacter on broiler carcasses.

Broiler carcasses were removed from commercial processing lines immediately after defeathering, before chilling, and after chilling to determine whether any relationship exists between aerobic bacteria and the human enteropathogens salmonellae and Campylobacter. In two experiments, a whole carcass rinse procedure was used to sample 30 carcasses after defeathering, 90 carcasses before chilling, and 90 carcasses after chilling, for a total of 210 different carcasses. Aerobic bacteria and Campylobacter spp. were enumerated and the incidence of salmonellae was determined. Salmonellae and Campylobacter incidences were 20 and 94%, respectively, for all carcasses sampled. After picking, neither salmonellae-positive nor Campylobacter-positive carcasses had mean aerobic most probable number (MPN) values that were different from carcasses negative for those organisms. Immediately before chilling, aerobic and Campylobacter counts were 7.12 and 5.33 log10 cfu per carcass, respectively. Immersion chilling reduced aerobic counts by approximately 1.8 log and Campylobacter by 1.5 log, with no change in salmonellae-positive carcasses. There was no difference in aerobic or Campylobacter counts between carcasses that were positive or negative for salmonellae at any of the sampling locations, nor was any correlation found between levels of aerobic organisms and Campylobacter. Carcasses with aerobic counts above the mean or more than one standard deviation above the mean also failed to show any correlation. Discriminant analysis indicated error rates as high as 50% when numbers of aerobic bacteria were used to predict incidence of salmonellae or Campylobacter on individual carcasses. Aerobic bacteria are not suitable as index organisms for salmonellae or Campylobacter on broiler carcasses.

Animals↗
PubMed1997

Duplex ultrasound criteria for the identification of carotid stenosis should be laboratory specific.

BACKGROUND AND PURPOSE: Published criteria for the determination of carotid stenosis have been widely applied by vascular laboratories. We compared two vascular laboratories and their duplex ultrasound (DU) machines in terms of their overall diagnostic performance and the optimal criteria to identify patients who have a 70% to 99% stenosis of the internal carotid artery. METHODS: Measurements of stenosis by DU and angiography were compared for 123 carotid arteries (60 arteries, laboratory A; 63 arteries, laboratory B). Receiver operating characteristic (ROC) curves were created, and the areas under the ROC curves and the optimal criteria for determining a 70% to 99% stenosis were compared. Multiple regression analysis was used to measure the effect of laboratory on the relationship between angiographic stenosis and DU velocity parameters. RESULTS: Areas under the ROC curves were similar for both laboratories (0.89 to 0.90, laboratory A; 0.90 to 0.92, laboratory B). However, the optimal criterion for the identification of a 70% to 99% carotid stenosis was different for each laboratory. For most velocity parameters, based on regression analyses, the predicted percent angiographic stenosis for laboratory A was significantly greater than that for laboratory B. In addition, performance differed between the laboratories when established criteria from the literature were applied. CONCLUSIONS: Two vascular laboratories with similar diagnostic accuracy by ROC analysis have markedly different "optimal" DU criteria. For a given angiographic stenosis, velocities in one laboratory were consistently greater than those in the other laboratory. Laboratory-specific criteria rather than published criteria should be used to identify patients with internal carotid artery stenoses.

Aged↗
PubMed1996

Infrainguinal arterial reconstruction with nonreversed greater saphenous vein.

PURPOSE: This study was undertaken to examine the effectiveness and the possible advantages of infrainguinal arterial reconstruction with nonreversed greater saphenous vein (NRGSV) grafts. We reviewed the results achieved with 189 consecutive NRGSV bypass procedures from July 1, 1985, to August 31, 1995, and compared them with 568 consecutive in situ greater saphenous vein (INGSV) bypass procedures completed over the same interval. METHODS: NRGSV bypass procedures were performed by selecting the optimum inflow and outflow vessels and then excising the best available appropriate-length segment of greater saphenous vein. The valves were lysed with a Mills valvulotome using gentle antegrade distention with an isotonic electrolyte solution containing heparin (1000 U/500 ml) and papaverine (60 mg/500 ml). The graft was then translocated to the inflow site, where the proximal and distal anastomoses were sequentially completed, followed by a completion arteriography. RESULTS: Demographic and risk factor characteristics did not differ between patients who underwent NRGSV and those who underwent INGSV bypass. Compared with INGSV bypasses, NRGSV bypasses were more commonly secondary procedures (26% vs 8%; p < 0.001) and were more often performed for limb salvage indications (89% vs 68%; p < 0.001). NRGSV bypasses also had more distal inflow vessels (23% superficial femoral artery [SFA] and 28% popliteal artery [POP] vs 10% SFA and 1% POP; p < 0.001) and more distal outflow vessels (52% tibial and 22% pedal artery vs 47% tibial and 3% pedal artery; p < 0.001) than did INGSV bypasses. Despite the higher incidence of secondary bypass procedures and more distal outflow vessels in the NRGSV group, the overall results achieved at 5 years did not differ between the two groups. The 5-year primary patency rates were 65% +/- 5% for NRGSV and 72% +/- 3% for INGSV (p < 0.12), and the 5-year secondary patency rates were 74% +/- 5% and 82% +/- 2% (p < 0.08), respectively. Similarly, the 5-year limb salvage rate among bypass procedures performed for limb salvage indications did not differ for NRGSV (82% +/- 5%) and INGSV (90% +/- 2%; p < 0.06). CONCLUSIONS: The application of the NRGSV bypass graft preserves the INGSV's main advantage of optimal size match between artery and vein at each anastomosis, but facilitaties the tailoring of the procedure to the patients anatomy and the completion of the bypass with the shortest, best-quality conduit available. Our application of the NRGSV in a more challenging series of bypass procedures produced equivalent results to those achieved in a concurrent series of INGSV bypass procedures.

Aged↗