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Biomedical subjects

W M Whitehouse

Publications and source records attributed to W M Whitehouse.

At least 19 recordsLinked to original sources
PubMed2003

Can ulnar artery velocity changes be used as a preoperative screening tool for radial artery grafting in coronary artery bypass?

Radial artery harvesting for coronary revascularization may result in digit ischemia if collateral circulation is inadequate. The purpose of this study was to compare changes in ulnar artery flow velocity during radial artery compression (RAC) with changes in first- and second-digit pressures during RAC, a previously validated predictor of digital ischemia. Photoplethysmography was used to measure first- and second-digit arterial pressures before and during RAC on 80 extremities. Color flow duplex imaging was used to measure distal ulnar artery peak systolic velocity before and during RAC. Seventy-eight of eighty extremities had a slight increase in ulnar artery velocity with RAC. There was no correlation between ulnar artery velocity changes and digit pressure changes. Measurement of ulnar artery velocity during RAC is not a useful predictor of digit pressure changes. Measurement of segmental upper extremity pressures with first- and second-digit pressure measurement during radial artery compression should remain the preferred preoperative screening tool for radial artery harvest prior to CABG.

Adult↗
PubMed2001

Upper extremity venous gangrene following coronary artery bypass. A case report and review of the literature.

Acute symptomatic upper extremity deep vein thrombosis (DVT) are estimated to account for only 2-4% of all deep vein thrombosis. Upper extremity DVT leading to phlegmasia cerulea dolens (PCD) occurs in an estimated 2-5% of these cases. Progression of PCD to venous gangrene is extremely rare with only 16 previously reported cases in the literature. Only 7 of the cited cases document significant tissue loss. This report describes a 61-year-old male who developed upper extremity DVT complicated by PCD which led to venous gangrene and limb loss.

Amputation, Surgical↗
PubMed1999

Noninvasive evaluation of hand circulation before radial artery harvest for coronary artery bypass grafting.

OBJECTIVE: Radial artery harvesting for coronary artery bypass may lead to digit ischemia if collateral hand circulation is inadequate. The modified Allen's test is the most common preoperative screening test used. Unfortunately, this test has high false-positive and false-negative rates. The purpose of this study was to compare the results of a modified Allen's test with digit pressure change during radial artery compression for assessing collateral circulation before radial artery harvest. METHODS: One hundred twenty-nine consecutive patients were studied before coronary artery bypass operations. A modified Allen's test was performed with Doppler ultrasound to assess blood flow in the superficial palmar arch before and during radial artery compression. A decreased audible Doppler signal after radial artery compression was considered a positive modified Allen's test. First and second digit pressures were measured before and during radial artery compression. A decrease in digit pressure of 40 mm Hg or more (digit DeltaP) with radial artery compression was considered positive. RESULTS: Seven of 14 dominant extremities (50%) and 8 of the 16 nondominant extremities (50%) with a positive modified Allen's test had a digit DeltaP of less than 40 mm Hg (false positive). Sixteen of 115 dominant extremities (14%) and 5 of 112 nondominant extremities (4%) with a negative Allen's test had a digit DeltaP of 40 mm Hg or more with radial artery compression (false negative). CONCLUSION: Use of the modified Allen's test for screening before radial artery harvest may unnecessarily exclude some patients from use of this conduit and may also place a number of patients at risk for digit ischemia from such harvest. Direct digit pressure measurement is a simple, objective method that may more precisely select patients for radial artery harvest. Additional studies are needed to define objective digital pressure criteria that will accurately predict patients at risk for hand ischemia after radial harvest.

Adult↗
PubMed1997

Incidence and pathophysiologic significance of infected carotid artery plaque.

It is unknown whether an association exists between infectious microorganisms and atherosclerosis. Eighty consecutive patients undergoing carotid endarterectomy were studied to detect for bacterial or virus infections in removed carotid atherosclerotic plaques. Twenty-one patients (25%) were found to have positive cultures for bacteria of the carotid plaques. Three patients (4%) did not have bacterial contamination of controlled cultures of the skin. Of these three patients, two grew diptheroids and one grew staphylococcus. The control cultures of the skin demonstrated that 25 patients (31%) grew diphtheroids and 29 (36%) grew staphylococcus. Five patients grew both organisms. There was no evidence of colonization within the atheromatous plaque material in histologic studies of the three patients that had positive cultures of their plaque. All viral cultures were negative. The positive carotid cultures found were most likely due to contamination from the skin. This study demonstrates the unlikelihood of bacterial or virus infections as either an etiologic or a pathogenetic factor in carotid artery atherogenesis.

Aged↗
PubMed1988

The effect of protamine sulfate on platelet function.

The adverse effects of protamine sulfate, used to neutralize the anticoagulant action of heparin, include systemic hypotension, pulmonary artery hypertension, thrombocytopenia and leukopenia. For further evaluation of protamine's mechanism of action, a three-part investigation was performed. In part I platelet-rich plasma (PRP) was prepared from canine blood samples (n = 6) taken before and 2 minutes after injection of protamine. In part II human PRP (n = 5) was preincubated with protamine or distilled water. Adenosine diphosphate-induced aggregation of protamine-treated platelets was unchanged, but thrombin-induced aggregation was inhibited in both canine and human preparations (p less than 0.05). In part III thrombocytopenia was produced in splenectomized dogs (n = 5), using microporous filters, to 4.5-8.4% of the initial platelet count. Protamine reversal of the heparinization caused hypotension (maximally -29 mmHg 90 s after protamine), but not pulmonary arterial hypertension. Leukopenia developed before additional thrombocytopenia appeared. Protamine-platelet interaction inhibits thrombin-induced platelet aggregation. Platelets may play an important role in the pulmonary pressure rise during protamine reversal, but do not mediate the systemic hypotension.

Animals↗
PubMed1987

Protamine reversal of anticoagulation achieved with a low molecular weight heparin. The effects on eicosanoids, clotting and complement factors.

Hemodynamic and hematologic effects of protamine reversal of low molecular weight heparin (LMWH) anticoagulation with and without protamine pretreatment, as well as reversal of anticoagulation with unfractionated standard heparin (SH), were studied in canine subjects. Protamine reversal caused less severe thrombocytopenia in the two LMWH groups compared to SH animals, while neutropenia occurred equally in all groups. Cl-esterase inhibitor levels were minimally increased, whereas C3 levels and leucotriene levels were unaltered. TxB2 and 6-keto-PGF1 alpha increased during protamine reversal of LMWH anticoagulation. TCT and APTT were affected less with LMWH than SH anticoagulation. Anti-Xa levels increased with anticoagulation in all animals, but protamine did not reverse the elevated anti-Xa levels in LMWH anticoagulated dogs to the same degree as occurred with SH anticoagulation. TCT, APTT and bleeding times were normalized by protamine in all animals. Protamine reversal of LMWH anticoagulation with or without protamine pretreatment did not reveal any clear differences in eicosanoids or complement factors compared to SH anticoagulation, although differences in anti-Xa activity clearly separated these two heparins.

Animals↗
PubMed1987

Presentation and perioperative management of arterioportal fistulas.

Arterioportal fistulas (APFs) are usually traumatic in origin and may result in portal hypertension and its complications. Over six years, six patients (aged 20 to 59 years) presented with APFs. Two APFs developed after percutaneous liver biopsy, but only one was complicated (hemobilia). Neither patient was treated operatively. Four APFs occurred two days to three years after gunshot wounds. Three patients presented with gastrointestinal tract hemorrhage. All patients had abdominal bruits. Two patients underwent primary repair. One patient underwent APF resection and replacement of the superior mesenteric artery with autogenous vein. Another patient underwent APF and bowel resection. Three patients survived. One patient died of liver failure. The development of an abdominal bruit in a patient with penetrating abdominal trauma suggests APF and should prompt angiography. Elective repair is recommended before complications of portal hypertension develop.

Adult↗
PubMed1987

Haemodynamic and haematologic alterations with protamine reversal of anticoagulation: comparison of standard heparin and a low molecular weight heparin fragment.

Reversal of anticoagulation with protamine sulfate causes many adverse haemodynamic and haematologic effects which could be due to differences in the mechanism of action of standard and low molecular weight heparin. Three groups of dogs were investigated: one group received normal saline pretreatment followed by heparinisation with standard heparin 150 IU/kg followed by protamine sulfate reversal 1.5 mg/kg after aortic interposition grafting: the second group were given normal saline pretreatment followed by heparinisation with low molecular weight heparin 150 U antiXa/kg and after grafting protamine sulfate reversal 1.5 mg/kg. The third group were given protamine sulfate pretreatment 2.25 mg/kg followed by low molecular weight heparin 150 U antiXa/kg and later protamine sulfate reversal 1.5 mg/kg after grafting. The same haemodynamic changes were seen regardless of the type of heparin or pretreatment with protamine given along with low molecular weight heparin. There was a suggestion that regular heparin cause a more pronounced increase in pulmonary artery pressure and a decrease in heart rate. On the other hand the systemic hypotension and reduction of cardiac output seemed more pronounced in the low molecular weight heparin group. Platelet count decreased less in the low molecular weight heparin group, but white blood cell count was equally reduced. Pretreatment with protamine did not abolish the adverse effects of protamine when reversing anticoagulation achieved with low molecular weight heparin, a finding not shared with standard heparin-protamine interactions.

Animals↗
PubMed1987

Treatment of established prosthetic vascular graft infection with antibiotics preferentially concentrated in leukocytes.

The efficacy of treating established vascular graft infections with rifampin and clindamycin (preferentially concentrated in leukocytes) and cefazolin (not concentrated in leukocytes) was studied in a canine model. Infrarenal aortic, 6 mm by 6 cm knitted Dacron double velour grafts were implanted and infected with 10(8) colony-forming units (CFU) of coagulase-positive Staphyloccus aureus organisms injected intravenously immediately after graft placement. Antibiotic therapy was instituted at 3 months postimplantation. Three groups were studied: (I) untreated controls (n = 3); (II) therapy with intravenous cefazolin 15 mg/kg/8 hr for 28 days (n = 7); and (III) combined therapy with intravenous rifampin 13 mg/kg/24 hr and intravenous clindamycin 13 mg/kg/8 hr for 28 days (n = 7). Grafts were removed for quantitative bacteriologic studies after the 28-day course of therapy. Two group I control grafts remained patent with 6.4 X 10(6) and 8.1 X 10(3) CFU S. aureus/gm of graft. The third control graft was thrombosed. Two group II animals demonstrated 1.6 X 10(7) and 2.3 X 10(5) CFU S. aureus organisms/gram of graft, respectively; the remaining five group II grafts were free of organisms. All group III grafts were sterile--a significant difference (p less than 0.05) from group I grafts. In this experimental model, established prosthetic graft infections were eradicated by intensive treatment with antibiotics preferentially concentrated in leukocytes.

Animals↗
PubMed1986

Nuclide imaging of vascular graft-platelet interactions: comparison of indium excess and technetium subtraction techniques.

Indium-111-labeled platelet adherence to ePTFE thoracoabdominal vascular prostheses in a canine model (n = 10) was quantitated by (1) an indium-111 excess technique, contrasting graft radioactivity to that in a reference region, and (2) a technetium-99m subtraction technique, with radioactivity of circulating platelets eliminated by discounting background blood activity. Variation in graft thrombogenicity was provided by seeding six prostheses with enzymatically derived autologous endothelial cells, and implanting four prostheses without seeding. Grafts were imaged at 1, 4, and 6 weeks postimplantation, with platelet labeling using indium-111-oxine and red blood cell labeling using technetium-99m. At 7 weeks grafts were excised and gamma activity was measured in proximal, middle, and distal segments. Luminal generation of TxB2 and 6-keto-PGF1 alpha from midportions of grafts was assayed. Indium-111 excess ratios at 6 weeks correlated with actual gamma activity of excised grafts (proximal r = 0.80, P less than 0.01; middle r = 0.73, P less than 0.05; distal r = 0.48, ns) but such a correlation did not exist for the technetium-99m subtraction technique (r = -0.05, -0.25, and 0.16, in the three segments, respectively, all ns). The ratio of graft to aortic TxB2 production revealed a positive correlation with graft gamma activity (r = 0.87, P less than 0.01), and the ratio of graft 6-keto-PGF1 alpha to TxB2 production also correlated with gamma counts (r = -0.64, P = 0.05). In this experimental setting technetium-99m subtraction analysis was an imprecise method of detecting graft platelet accumulation, whereas indium-111 excess ratios proved to be a more accurate method of quantitating vascular prosthetic thrombogenicity.

Animals↗
PubMed1986

Protamine pretreatment attenuation of hemodynamic and hematologic effects of heparin-protamine interaction. A prospective randomized study in human beings undergoing aortic reconstructive surgery.

Hemodynamic and hematologic responses to protamine sulfate reversal of heparin's anticoagulant effects were studied in 15 consecutive randomized patients undergoing aortic reconstructive surgery. In a double-blinded manner, patients were pretreated with either normal saline solution (n = 8) or protamine (0.75 mg/kg/3 min, n = 7) 5 minutes before heparinization (150 IU/kg). After aortic grafts were placed, protamine (1.5 mg/kg/3 min) was administered intravenously to reverse the heparin. Arterial blood pressure, heart rate, pulmonary artery and capillary wedge pressure, central venous pressure, and cardiac output were monitored, as were platelet count, white blood cell count, activated clotting time, total hemolytic complement levels, and C3a levels. Calculated parameters included systemic vascular resistance and pulmonary vascular resistance. Pretreatment with protamine compared with saline solution prevented the hypotension (+6 vs. -16 mm Hg, p less than 0.05) and declining pulmonary artery pressure (+1 vs. -7 mm Hg, p less than 0.01) observed with protamine reversal of heparin. Significant differences between the two groups in central venous pressure and pulmonary vascular resistance were of less clinical relevance. Protamine pretreatment lessened the thrombocytopenia found during reversal compared with saline-pretreated patients although the difference was not statistically significant. Minimal hypotension occurring after protamine pretreatment alone was not accompanied by hemodynamic or hematologic changes, other than decreased heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Effects of continuous intravenous infusions of nitroglycerin on canine systemic and hind limb microcirculatory hemodynamics.

Systemic and hind limb hemodynamics were assessed in anesthetized dogs during continuous 30-minute intravenous infusions of nitroglycerin at 1, 5, 10, and 25 micrograms/kg/min. Nitroglycerin at 1 microgram/kg/min redistributed hind limb blood flow; hind limb arteriovenous shunting increased from 5.6% +/- 4.0% to 17.8% +/- 7.4% after 30 minutes (p less than 0.01); absolute hind limb shunt flow increased from 12 +/- 10 ml/min to 31 +/- 26 ml/min at 10 minutes (p less than 0.01); whereas hind limb nutrient blood flow decreased from 184 +/- 81 ml/min to 150 +/- 55 ml/min and 132 +/- 32 ml/min, respectively, at 10 and 30 minutes (p less than 0.05). Such hind limb blood flow redistribution was absent during infusion of all other nitroglycerin dosages. Total catecholamines increased at 30 minutes during both 1 and 10 micrograms/kg/min nitroglycerin infusions (p less than 0.05) with perhaps a slightly greater catecholamine response to 10 micrograms/kg/min after 30 minutes (0.05 less than p less than 0.10). The renin-angiotensin response at 3 minutes differed between nitroglycerin infusions of 1 and 10 micrograms/kg/min with an initial significant reduction from baseline in plasma renin activity at the lower dose compared with a significant increase from baseline in plasma activity at the higher dose. Nitroglycerin did not increase femoral artery flow or cardiac output and did not lower total peripheral vascular resistance at any dose studied. Despite this, arterial pressure and cardiac work were reduced at all nitroglycerin doses tested. Massive volume loading prevented the anticipated blood pressure reduction and blunted the expected cardiac work reduction during nitroglycerin infusions of 10 micrograms/kg/min. This study demonstrates that nitroglycerin is not a potent peripheral arteriolar vasodilator, 1 microgram/kg/min nitroglycerin infusions increase hind limb arteriovenous shunting and decrease hind limb nutrient blood flow, and myocardial work and arterial pressure reductions during nitroglycerin infusions appear to be caused by mechanisms other than generalized peripheral arterial dilation.

Animals↗
PubMed1986

Prostacyclin treatment of ischemic ulcers and rest pain in unreconstructible peripheral arterial occlusive disease.

The efficacy of prostacyclin (PGI2) treatment was assessed in 26 patients with surgically unreconstructible atherosclerotic arterial occlusive disease of the lower extremity manifested by nonhealing ulcers and rest pain. Patients were randomized to receive a 72-hour intravenous infusion of PGI2 (6 ng/kg/min, n = 13) or placebo (n = 13). Ulcer size was measured by photographic planimetry, and rest pain was graded by blinded objective scoring at monthly intervals for 6 months. Ulcer size increased 64% in PGI2-treated patients and 22% in placebo-treated patients by 1 month after infusion. Rest pain decreased slightly in both PGI2 and placebo groups. At the conclusion of the study, 54% of placebo-treated patients and 31% of PGI2-treated patients had a positive treatment response, indicated by at least a 20% decrease in ulcer size and a 33% decrease in rest pain. PGI2 infusion did not improve the high-placebo response rate seen in these patients with severely ischemic extremities. These results emphasize the importance of placebo-controlled studies, even in patients with unreconstructible arterial disease.

Aged↗
PubMed1986

Attenuation of hemodynamic and hematologic effects of heparin-protamine sulfate interaction after aortic reconstruction in a canine model.

This investigation documented the effect of protamine sulfate pretreatment on the adverse hemodynamic and hematologic sequela of rapid intravenous protamine administration in heparinized dogs having undergone prior implantation of aortic prostheses. Fourteen dogs underwent infrarenal aortic replacement with 6 mm inner diameter by 7 cm knitted Dacron double-velour grafts. Carotid arterial, central venous, and pulmonary arterial catheters were placed for continuous hemodynamic monitoring. All dogs were adequately anticoagulated with heparin (150 IU/kg) and reversed with protamine (1.5 mg/kg/10 sec) after graft insertion. Pretreatment regimens studied included normal saline (n4), protamine 0.75 mg/kg (n5), and protamine 2.25 mg/kg in three divided doses of 0.75 mg/kg each (n5). All pretreatment agents were administered 3 minutes before heparinization. Blood pressure (BP), heart rate (HR), pulmonary artery pressure (PAP) and cardiac output (CO) were measured. Hematologic assessments included platelet count (PC), leukocyte count, thrombin clotting time, and total hemolytic complement. Significant salutory effects were associated with protamine pretreatment regarding BP, HR, PAP, CO, and PC. It is concluded that adverse hemodynamic effects of protamine reversal are blocked and certain hematologic effects are reduced with protamine pretreatment before heparinization and its reversal in this canine experimental model.

Animals↗
PubMed1985

Brachiocephalic arterial occlusions and stenoses. Manifestations and management of complex lesions.

Complex stenotic and occlusive lesions involving multiple brachiocephalic arteries were encountered in 17 symptomatic patients, 25 to 76 years of age. Symptoms included hemispheric transient ischemic attacks (16), visual symptoms (ten), global cerebral ischemia (11), true syncope (six), upper extremity ischemic symptoms (eight), and frank tissue loss (one). Of 68 brachiocephalic arteries, 53 exhibited hemodynamically significant stenoses, including 21 that were totally occluded. Transthoracic surgical reconstruction consisted of bypass grafting (11), innominate artery endarterectomy (five), or proximal left common carotid endarterectomy with reimplantation into the contralateral carotid artery (one). There were no operative deaths and only one transient perioperative neurologic deficit. All patients had relief of symptoms. When multiple brachiocephalic arterial occlusions and stenoses preclude standard cervical reconstructive procedures, direct transthoracic reconstruction is appropriate and may be undertaken with acceptable risk in properly selected patients.

Adult↗