Biomedical subjects

K Ouriel

Publications and source records attributed to K Ouriel.

At least 109 records · Page 6Linked to original sources

PubMed1993

Predictive value of dobutamine echocardiography just before noncardiac vascular surgery.

This study prospectively evaluated 75 consecutive patients (mean age 69 +/- 9 years) undergoing major vascular surgery to test the hypothesis that dobutamine stress echocardiography can be used to predict perioperative cardiac events. A positive test was defined as a new or worsening wall motion abnormality in at least 2 of 18 wall segments. Up to 40 micrograms/kg/min of dobutamine was administered. All readings were done by physicians unaware of the patients' symptoms and electrocardiographic response. In addition, physicians caring for the patients were unaware of the test result. End points of the study were unstable angina with documented electrocardiographic changes, nonfatal myocardial infarction or cardiac death. The perioperative ischemic event rate was 7% (5 of 75 patients). Three patients developed unstable angina and 2 sustained nonfatal myocardial infarctions. All of these patients had positive results on dobutamine stress echocardiography (sensitivity 100%). However, 22 patients who also had positive results on dobutamine stress echocardiography did not have perioperative events (specificity 69%). The corresponding positive predictive value was 19%. None of the 48 patients who had negative results on dobutamine stress echocardiography had events (negative predictive value 100%). In conclusion, dobutamine stress echocardiography can be used to predict perioperative events with great sensitivity, but its positive predictive value in this patient population in low, likely due to the low incidence of perioperative events in patients with known coronary artery disease and the imperfect specificity of dobutamine stress echocardiography in identifying significant coronary stenosis. Dobutamine stress echocardiography is most useful in this setting when negative, because it predicts safety from complications with confidence.

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PubMed1993

Neurologic events following carotid endarterectomy: prediction of outcome.

A total of 1572 carotid endarterectomies were performed at one institution between 1975 and 1987. One hundred five patients had early (< 3 weeks) neurologic events following carotid endarterectomy. Sixty-five patients had cerebral vascular accidents (CVAs) (4.1%), 14 patients had reversible ischemic neurologic deficits (0.9%), and 26 patients had transient ischemic attacks (1.7%). Eight patients died from CVAs (0.5%). The mean follow-up was 31 months (range 1 to 137 months) with a 5-year cumulative survival of 77%. The median time of occurrence of neurologic events was 4 hours. Ages, cerebral protection, patches, carotid occlusion time (mean 29 minutes), gender, and status of the contralateral carotid arteries were not predictors of outcome. Death from neurologic events increased significantly in patients who had preoperative CVAs compared with patients with preoperative transient neurologic deficits (p < 0.05). The time of occurrence of CVA after carotid endarterectomy affected outcome, and an early CVA (< 4 hours) was associated with a higher mortality at 30 days and at 4 months as a consequence of the initial CVA (p = 0.11). Patients who had a neurologic event more than 4 hours after surgery had a significantly better resolution of their symptoms (66%) compared with patients who had an early neurologic event (35%, p < 0.05). The long-term follow-up of the surviving patients demonstrated an improvement in neurologic function in 75% of the CVA group (36/48) and 92% (76/83) of all patients who had neurologic events in long-term follow-up.

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PubMed1993

Intraoperative autotransfusion in aortic surgery.

PURPOSE: Intraoperative autotransfusion is frequently used in aortic surgery, despite the paucity of data regarding its safety and efficacy. This study was designed to compare whole blood autotransfusion with homologous transfusion for the replacement of blood lost during abdominal aortic procedures. METHODS: Whole blood autotransfusion was evaluated in 200 patients undergoing aortic reconstructive procedures during a 3-year period. Collection and reinfusion of unwashed filtered shed blood was undertaken in 100 patients, and clinical, laboratory, and economic parameters were compared with those in a group of 100 patients undergoing aortic operation with homologous banked blood replacement. RESULTS: The two groups were comparable with respect to demography, the type of procedure, baseline laboratory profile, and the frequency of coexistent medical illnesses. The amount of blood salvaged and reinfused averaged 1729 +/- 68 ml in the autotransfusion group. Patients undergoing autotransfusion received a mean of 0.6 +/- 0.1 units of banked blood during operation, compared with 3.4 +/- 0.1 units in the homologous group (p < 0.001). Operative morbidity and mortality rates were comparable between the groups, as were length of hospital stay and total hospital costs. Coagulopathy, renal insufficiency, abnormalities of oxygen exchange, and electrolyte disorders were infrequent. Autotransfusion offered significant advantages over homologous blood replacement with respect to improved preservation of circulating platelets (201 +/- 9 vs 157 +/- 6 x 10(3)mm3, p < 0.001) and coagulation factors (242 +/- 11 vs 196 +/- 14 mg fibrinogen/dl, p < 0.01) and limitation of exposure to homologous blood (34% vs 92%, p < 0.001). There was a significant cost advantage with the use of autotransfusion, with an average savings of $288 in hospital expenses associated with blood products and infusion equipment. Patients undergoing autotransfusion demonstrated aberrations in fibrin degradation products (33 +/- 4.4 vs 9.6 +/- 3.2 micrograms/ml, p < 0.001) and free plasma hemoglobin (29 +/- 9.1 vs 9.4 +/- 0.5 mg/dl, p < 0.05), but these laboratory abnormalities did not acquire clinical significance. CONCLUSION: These data suggest that autotransfusion of unwashed, filtered blood is a safe and efficacious alternative to homologous blood replacement in patients undergoing major aortic reconstructive procedures.

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PubMed1993

Transfemoral endovascular aortic graft placement.

PURPOSE: The purpose of this study was to develop an endovascular system for transfemoral placement of straight aortic grafts and bifurcated aortoiliac grafts. METHODS: Both types of graft consist of barbed, self-expanding stents attached to a woven polyester fabric. Survival studies of straight-graft function were performed in six large mongrel dogs. Digital subtraction fluoroscopic equipment was used to guide insertion and record angiograms at 0, 1, and 3 months. Bifurcated grafts were inserted in an additional eight dogs, four with distal stents and four without. Straight grafts were inserted into six cadaveric aortas (five atherosclerotic and one aneurysmal; age 68.7 + 5.7 years) to assess stent attachment. RESULTS: Angiograms obtained immediately after straight-graft insertion showed placement to be within 4.6 + 1.6 mm of the intended level. Follow-up angiograms at 1 and 3 months showed no migration, no leakage, and patency of all six grafts. After bifurcated graft insertion there were no angiographic signs of perigraft leakage, with or without distal stents. The mean force required to displace straight grafts 10 mm from their original position in cadaveric aortas was 1388 + 127 g. CONCLUSION: These preliminary results show that straight and bifurcated endovascular grafts can be positioned accurately and securely in the abdominal aorta.

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PubMed1993

Extension of limb salvage by combined vascular reconstruction and adjunctive free-tissue transfer.

PURPOSE: Vascular reconstruction alone can be insufficient for extremity salvage in some patients with severe soft-tissue wounds. We present our experience in 20 patients with vascular reconstruction for ischemic disease and free-tissue transfer for limb-threatening soft-tissue wounds. METHODS: Nineteen patients underwent autogenous venous bypasses and one patient underwent an aortobifemoral bypass. Ten soft-tissue reconstruction were performed at the time of the vascular reconstruction and 10 were delayed. Free-tissue transferred included muscle, fasciocutaneous flaps, and omentum. Inflow to the flap was from the bypass graft (n = 12) or the distal tibial artery. RESULTS: One free flap and graft failed immediately in the same patient. One successful flap and graft required a below-knee amputation for ongoing infection in the surrounding soft tissues. Eighteen of 20 patients have had free-flap and graft patency during the mean follow-up period of 17 months (range 6 to 33 months). These 18 patients ambulate independently. CONCLUSIONS: In patients with arterial insufficiency and severe soft-tissue wounds, combined vascular reconstruction and free-tissue transfer permits extended limb salvage with excellent functional results.

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PubMed1993

Nasopharyngeal perforation as a complication of nasogastric intubation.

We report a patient with nasopharyngeal perforation associated with nasogastric intubation. Diagnosis of the perforation was accomplished by roentgenograms of the neck and identification of the site by fiberoptic endoscopy and a water-soluble radiographic contrast agent. The extent of subcutaneous emphysema and lack of extraluminal fluid collections was documented by CT scan. Early diagnosis allowed for successful treatment with intravenous antibiotics.

Humans↗

PubMed1992

Peroneal artery bypass: a multifactorial analysis.

Sixty-two bypass grafts to the peroneal artery were performed at the University of Rochester Medical Center between 1984 and 1990. An autogenous conduit was used in 45 patients and a prosthetic conduit in 17 patients. Primary cumulative patency rates were 49% at two years and 30% at four years following operation. Limb salvage was achieved in 68% of patients. The two year cumulative patency rate was significantly better when the peroneal artery was of good quality arteriographically compared with those in which stenoses were present (75% versus 25%, p less than 0.05); in patients without inflow disease compared with patients with inflow disease (56% versus 11%, p less than 0.05); and in saphenous vein grafts compared with prosthetic grafts (55% versus 17%, p less than 0.05). The factors that did not influence patency were the presence of a direct peroneal collateral vessel filling a pedal vessel, age, sex, diabetes, and the size of the peroneal artery. The results of peroneal artery bypass in end-stage patients are dependent on the presence of adequate autogenous vein and a recipient peroneal vessel free of disease. Under these circumstances, the results of the procedure approach that of standard femorotibial reconstruction.

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PubMed1992

Pulmonary embolism from left subclavian vein thrombus following suprapubic prostatectomy.

Deep venous thrombosis (DVT) of the axillary and subclavian veins accounts for approximately 1-2 percent of all recorded deep venous thrombosis. Pulmonary embolism from an upper extremity DVT has been reported to vary between 2 percent and 35.7 percent. We report the occurrence of a left subclavian vein DVT with subsequent nonfatal pulmonary embolism in a sixty-two-year-old patient twenty-four hours following suprapubic prostatectomy. A review of the literature is presented, along with pathophysiology, diagnosis, and treatment.

Humans↗

PubMed1992

An evaluation of new methods of expressing aortic aneurysm size: relationship to rupture.

The diameter of aortic aneurysms were standardized to measures of patient size and normal aortic size in an effort to define indexes that might be more predictive of aneurysm rupture than raw aneurysm diameter alone. Normal aortic diameters were measured in 100 patients undergoing abdominal CT scans for other reasons, and an average infrarenal aortic diameter of 2.10 +/- 0.05 cm was observed. Normal aortic diameter was dependent on both age and sex, ranging from 1.71 +/- 0.06 cm in women below age 40 years to 2.85 +/- 0.04 cm in men above age 70 years. Overall, 11 (5.1%) of the ruptures occurred in aneurysms less than 5 cm in diameter, and four (1.9%) occurred in aneurysms less than 4.0 cm in diameter. When the CT scans of 100 patients undergoing elective aneurysm resection were compared with those of 36 patients with ruptured aneurysms, no threshold diameter value accurately discriminated between the two groups. However, standardization of the aneurysm diameter to the transverse diameter of the third lumbar vertebral body as an index of patient body size produced an accurate predictor of rupture when a threshold ratio of 1.0 was used. No aneurysm ruptured below this ratio, but 29% of elective aneurysms were smaller than the vertebral body diameter. Receiver operating characteristic curve analysis confirmed the superiority of the aneurysm to vertebral body diameter ratio as a discriminator of ruptured aneurysms. It appears that aneurysm diameter alone is not sufficiently predictive of rupture to be used as the sole indication for elective resection.

Adult↗

PubMed1992

Vascular disease in the antiphospholipid syndrome: a comparison with the patient population with atherosclerosis.

The antiphospholipid syndrome was diagnosed in 19 of 1078 patients treated between 1987 and 1991. All patients with antiphospholipid syndrome had either anticardiolipin antibody (16/19) or lupus anticoagulant (10/19); three patients had thrombocytopenia, eight patients had a prolonged partial thromboplastin time, and 10 patients had an elevated erythrocyte sedimentation rate. The most common site of involvement was the cerebral circulation (nine patients), manifested by transient ischemic attacks or stroke. Eight patients had upper extremity disease, characterized by symptoms of Raynaud's phenomenon, with angiographic lesions involving the brachial, radial, ulnar, and/or digital arteries. Lower extremity disease occurred in seven patients, with clinical presentations similar to those of atherosclerosis and varying angiographic patterns. In comparison with the population having atherosclerosis, patients with arterial manifestations of antiphospholipid syndrome were more likely to be women (13 of 19 versus 411 of 1078, p less than 0.02), were significantly younger (46.2 years versus 63.6 years, p less than 0.0001), did not smoke (1 of 19 patients versus 700 of 1078, p less than 0.0001), had a higher percentage of upper extremity involvement (8 of 18 versus 13 of 1078, p less than 0.0001), and had a higher incidence of early graft failure (9 of 12 grafts versus 13 of 371 grafts, p less than 0.0001). The syndrome is associated with the repetitive failure of vascular reconstructions and occlusion of native vessels. Antiphospholipid syndrome should therefore be suspected in young, female, nonsmokers with vascular disease, especially those with involvement of the upper extremity, cerebrovascular disease with normal findings on extracranial carotid angiography, and premature graft failure.

Adult↗

PubMed1992

Future alternatives to heparin: low-molecular-weight heparin and hirudin.

The antithrombotic effects of standard heparin were compared with those of low-molecular-weight heparin (LMWH) and hirudin by use of an in vitro perfusion system. Fresh blood collected from human volunteers was treated with varying doses of these three agents and perfused in a recirculating system over everted porcine vein segments. A low shear rate (100/sec) was selected to simulate conditions in large arteries and veins. Platelet and fibrinogen deposition were evaluated with indium 111 and iodine 125 radiolabels, respectively. Anticoagulant activity was assessed by measuring the activated clotting time (ACT). Anti-Xa activity was assayed to determine the degree to which these agents used antithrombin III pathways. Low-molecular-weight heparin was the weakest anticoagulant, requiring 32 micrograms/ml blood to double the ACT. By contrast, the ACT doubled with only 0.75 and 1.10 micrograms/ml blood of heparin and hirudin, respectively. Heparin and hirudin inhibited platelet and fibrin deposition at equivalent doses. Low-molecular-weight heparin was a less potent inhibitor of fibrin than heparin or hirudin. Hirudin, a direct thrombin inhibitor, exhibited minimal anti-Xa activity, contrasted with 0.14 anti-Xa units/micrograms for LMWH and 0.13 anti-Xa units/mg for heparin. These data suggest that heparin and hirudin are more potent anticoagulants and antiplatelet agents than LMWH.

Analysis of Variance↗

PubMed1991

Clinical evaluation of stenosis of the carotid bifurcation with magnetic resonance angiographic techniques.

We evaluated the images of 60 carotid artery bifurcations in 31 patients suspected to have carotid artery disease who underwent invasive carotid angiography and combined two-dimensional, phase-sensitive and a gradient-echo magnetic resonance angiography. The phase scans consisted of seven serial projections that were obtained at 20 degrees intervals (11.0 minutes) around the carotid bifurcation; the gradient-echo (GRASS) scans were composed of 11 axial images (2.4 minutes) acquired through the bifurcation. The two magnetic resonance angiographic techniques yielded complementary pieces of information and were used together to compare magnetic resonance angiography with invasive angiography. Comparison of magnetic resonance and invasive angiograms of the 60 carotid arteries shows that the sensitivity (86%) and specificity (92%) of the magnetic resonance angiographic techniques we used to diagnose clinically significant carotid stenosis approach but do not reach those of invasive angiography.

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PubMed1991

The clinical course of residual carotid arterial disease.

Over a 5-year period 642 patients underwent 686 carotid endarterectomies with patch closure and intraoperative surveillance with continuous-wave Doppler. The perioperative stroke rate was 1.5%. Patients were screened with duplex scans immediately after operation for the presence of residual carotid lesions, and followed every 3 to 6 months for either the development of a true recurrent lesion or a change in a residual one. Five hundred thirty-nine arteries (84%) had no postoperative abnormalities. The incidence of recurrent carotid lesions in this groups was 1.5%, 3.4%, and 5.2% at 1, 2, and 3 years, respectively. The incidence of symptoms in this group was 0.2%, 0.7%, and 1.4% at 1, 2, and 3 years, respectively. The earliest recurrence or symptom occurred 8 months from operation. One hundred forty-seven arteries had residual lesions that were more common when either a temporary shunt was used or the operation was carried out above the hypoglossal nerve or below the omohyoid muscle. Sixty-one patients who had plaque proximal to the arteriotomy without a significant stenosis were followed an average of 21 months. There were no changes in plaque morphology and no proven symptoms related to the residual lesion. Fifty-six patients with both plaque and significant hemodynamic abnormalities in the carotid bulb were followed an average of 18 months. Seven of these patients (12.5%) had either a significant deterioration of the lesion or a symptom from it. Each event occurred within 6 months of operation. Thirty patients had significant flow abnormalities but no visible plaque. None of these lesions deteriorated. Although common, residual carotid lesions are benign unless the lesion is characterized by both plaque within the artery and a hemodynamically significant stenosis. These lesions should be further investigated and treated when discovered.

Arteriosclerosis↗

PubMed1991

Laser angioplasty in peripheral vascular disease: symptomatic versus hemodynamic results.

Most early reports on the efficacy of laser angioplasty have used subjective symptoms rather than objective hemodynamic parameters to evaluate clinical results. We reviewed our experience with hot tip laser-assisted balloon angioplasty in 99 occluded or stenotic arterial segments during 80 procedures in 71 patients, ranging from the aortic bifurcation to the tibial-peroneal trunk. Initial failure to successfully recanalize occluded or stenotic segments occurred in 13 instances (16%). Forty-one procedure-related complications occurred in 31 patients (39%). Functional results were evaluated by use of life-table methods on the basis of symptomatic versus hemodynamic improvement. Cumulative patency rates for symptomatic and hemodynamic improvement were 91% and 64% at 1 month, 71% and 48% at 6 months, and 57% and 34% at 1 year, respectively. These data suggest that symptomatic improvement alone gives a misleadingly high estimate of the efficacy of laser angioplasty when compared with more objective hemodynamic criteria (p less than 0.005). Hemodynamic success was more likely in aortoiliac lesions than femoropopliteal lesions (58% vs 18% at 1 year, p less than 0.01). Hemodynamic parameters should be used to evaluate the success of laser angioplasty, which in its present form, is associated with frequent complications and poor long-term success.

Adult↗

PubMed1991

Low dose heparin therapy: in vitro verification of antithrombotic effect.

Low dose heparin therapy has been used routinely for prophylaxis of deep venous thrombosis, yet in vitro data regarding its antithrombotic effects are sparse. The effects of heparin on venous thrombus formation were studied in an in vitro perfusion system. Fresh blood collected from human volunteers was treated with varying heparin doses and perfused at a shear rate of 100 sec-1 over everted, injured porcine vein segments, simulating conditions in the venous circulation. Platelet and fibrin deposition were measured by use of indium 111 and iodine 125 radiolabels, respectively. The effects of heparin on the intrinsic coagulation cascade were monitored by the activated clotting time. Increasing doses of heparin resulted in significant reductions in fibrin and platelet deposition (ANOVA F = 2.67 and 3.17, respectively, p less than 0.05). At a dose of only 0.19 USP units/ml blood, equivalent to a 1000 unit bolus of heparin in a 70 kg man, a noticeable reduction in both fibrin and platelet deposition was observed without an increase in the activated clotting time. These data confirm the antithrombotic effects of heparin at low dose ranges and may explain the clinically observed phenomenon of deep venous prophylaxis without an appreciable alteration in the conventional coagulation assays.

Animals↗

PubMed1991

The hemodynamics of thrombus formation in arteries.

Alterations in arterial blood flow are thought to predispose to thrombus formation, but the exact relationships have not been fully elucidated. The effect of varying blood flows on the accumulation of thrombotic material within arteries was investigated, with use of shear rate as an index of flow across the luminal surface. Partially denuded rabbit aortas were perfused with fresh nonanticoagulated human blood for 3 minutes, with an in vitro recirculating apparatus, Indium 111-labeled platelets, and fibrinogen I 125. Shear rates ranged from zero to 1500 sec-1, correlating with the hemodynamics of various segments of the human arterial tree. A significant correlation was observed between shear rate and platelet deposition, ranging from 5.2 +/- 2.8 x 10(6) platelets/cm2 of vessel surface area at zero shear to a maximum of 64.7 +/- 8.3 x 10(6) platelets/cm2 at a shear rate of 1500 sec-1 (F = 5.01, p less than 0.05). Fibrin deposition paralleled that of platelets, ranging from 28.2 +/- 7.6 micrograms/cm2 at zero shear to 354.1 +/- 62.7 micrograms/cm2 at a shear rate of 1500 sec-1 (F = 5.91, p less than 0.05). These results suggest that shear rate is a most important determinant of platelet and fibrin deposition on altered arterial surfaces.

Animals↗

PubMed1991

Long-term follow-up after thoracic outlet decompression: an analysis of factors determining outcome.

We reviewed our 12-year experience with transaxillary first rib resection in 136 patients screened by neurologists and thought to have neurologic thoracic outlet syndrome to determine what factors affected outcome. These patients represented 85% of the operative experience in a referral area of 1.2 million people. Patients were recalled every 2 years for surveillance. The mean follow-up was 60 +/- 7 months. There were no brachial plexus or vascular injuries. Secondary operations in the neck were required in 20 patients. The quality of the operative result was determined by whether the patient was able to return to preillness activities and whether the patient would undergo operation again if the same result would be obtained. The most important determinant of result was a history of trauma precipitating the neurologic symptoms, particularly in women. Only 25 of the 53 patients (47%) with a history of trauma returned to preillness activities compared to 65 of the 83 patients (78%) without such a history. Overall patient satisfaction was not affected by trauma. Thirty-eight of the 53 patients with trauma (72%) and 69 of the 83 patients (83%) without trauma were satisfied. When the men and women were analyzed separately men were found to have better results after trauma than did women. Other factors with a negative impact on operative results were the need to return to an activity that required repetitive arm movements, coverage under a worker's compensation insurance policy, and fixed joint abnormalities or neurologic findings in the upper extremity. The presence of an anatomic abnormality had no effect on operative results.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗

PubMed1991

Popliteal artery aneurysms: a 25-year surgical experience.

Operative repair was undertaken for 51 popliteal aneurysms in 39 patients between 1958 and 1990. Operation was performed on an emergency basis in 19 extremities with limb-threatening ischemia and as an elective procedure in 32 extremities. Cumulative limb salvage (94%) rates and patency rates (67%) became significantly different at 6 years (p less than 0.05). Graft patency was affected by clinical presentation and runoff. After 1 year, cumulative patency for extremities with limb-threatening ischemia was significantly lower than for those having an elective operation (69% vs 100%, p less than 0.05). Runoff did not influence graft patency until 3 years, at which time cumulative patency was better in extremities with good runoff than in extremities with poor runoff (89% vs 30%, p less than 0.05). Limb salvage was affected only by presentation. All limb loss (three patients) occurred within the first month in extremities with graft occlusion after operation for limb-threatening ischemia. Runoff did not influence patency rates for extremities with limb-threatening ischemia, since no difference was observed in runoff between the two groups. We conclude that elective repair is indicated in all patients with popliteal aneurysms. It is associated with little risk to the patient, and prevents the need for operation in the setting of limb-threatening ischemia with its poorer overall results and definite incidence of amputation.

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