Biomedical subjects

W C Mackey

Publications and source records attributed to W C Mackey.

At least 55 records · Page 3Linked to original sources

PubMed1990

Carotid endarterectomy contralateral to an occluded carotid artery: perioperative risk and late results.

To define better the short-term risk and long-term benefit of carotid endarterectomy opposite an occluded carotid artery, we reviewed our experience since 1961. Angiographic data are available for 598 of 670 (89.3%) patients in our carotid registry. In 63 (10.5%) patients the internal or common carotid artery on the side opposite the endarterectomy was occluded. All operations were carried out under general anesthesia with selective shunting based on electroencephalographic criteria. Shunting was required in 29 of 63 (46.0%) patients with contralateral occlusion and 72 of 535 (13.5%) control subjects (p less than 0.0001). Perioperative strokes occurred in 3 of 63 (4.8%) patients with contralateral occlusion and 14 of 535 control subjects (2.6%) (p = 0.23). Perioperative death occurred in 0 of 63 patients with contralateral occlusion and 6 of 535 (1.1%) control subjects (p = 0.40). Life-table cumulative stroke-free rates at 1, 5, and 10 years were 95.2%, 91.0%, and 76.2% in the group with contralateral occlusion and 96.0%, 89.4%, and 84.1% in control subjects (p = 0.25). Life-table cumulative survival rates at 1, 5, and 10 years were 93.1%, 80.8%, and 75.4% in the group with contralateral occlusion and 94.8%, 77.0%, and 57.9% in control subjects (p = 0.58). Carotid endarterectomy contralateral to an occluded carotid artery may be carried out with acceptable risk and late stroke-free and survival rates comparable to those seen in other patients who have undergone carotid endarterectomy.

Arterial Occlusive Diseases↗

PubMed1990

Ibuprofen pretreatment inhibits prostacyclin release during abdominal exploration in aortic surgery.

Mesenteric traction during aortic surgery produces facial flushing, reduced mean arterial pressure (MAP), and systemic vascular resistance (SVR) with increased heart rate (HR) and cardiac index (CI). Elevated 6-keto-prostaglandin-F1 alpha (6-keto-PGF1 alpha) suggests prostacyclin is the mediator. To test this hypothesis, the cyclooxygenase inhibitor, ibuprofen (n = 14), or placebo (n = 13) was administered to patients electively scheduled for aortic reconstruction. The hemodynamic measurements and plasma concentrations of prostanoids between groups were compared immediately before (0), and 5, 10, 15, 30, and 45 min following mesenteric traction. Following mesenteric traction significant differences (P less than 0.05) were observed between the ibuprofen pretreatment and placebo group over time in SVR, MAP, HR, CI, 6-keto-PGF1 alpha, and thromboxane B2 (TXB2). Significant differences between groups at individual times were found in SVR, HR, CI, 6-keto-PGF1 alpha, and TXB2. In the placebo group flushing was accompanied by reduced SVR and MAP and increased HR and CI. The greatest effect was seen at 10 min and resolved over 30 min. Plasma concentration of 6-keto-PGF1 alpha increased from 159 +/- 103 (mean +/- SEM) pg/ml to a peak value of 3,765 +/- 803 at 10 min. A late increase in TXB2 occurred with a peak value of 1,970 +/- 891 (mean +/- SEM) pg/ml at 30 min. In the ibuprofen pretreated group no significant changes occurred in hemodynamic measurements or concentrations of prostanoids. The inhibition of 6-keto-PGF1 alpha and its associated hemodynamic changes in the treatment group, but not in the placebo group, confirms the hypothesis that prostacyclin is the mediator of the mesenteric traction response in abdominal aortic surgery.

6-Ketoprostaglandin F1 alpha↗

PubMed1990

Long-term results with the above-knee popliteal expanded polytetrafluoroethylene graft.

Since approximately 30% to 40% of autogenous vein bypass grafts to the femoropopliteal level may occlude within 5 years of implantation, additional vein will be required for subsequent revisions. We undertook a study to determine whether the preferential use of an above-knee expanded polytetrafluoroethylene bypass graft to save vein is an appropriate option. We reviewed our experience with 114 above-knee expanded polytetrafluoroethylene bypass reconstructions. Life-table analysis of primary and secondary graft patency was carried out by the method of Peto and statistically analyzed for the influence of clinical indication, runoff as determined by both preoperative and intraoperative completion arteriography, smoking, and diabetes. The 5-year primary patency rate of 57% for patients with claudication was comparable to contemporary randomized or retrospective series with below-knee autogenous vein for that indication, and it was superior to the patency rate for limb salvage. The status of the runoff vessels was an important determinant of outcome. The 59 limbs with good arteriographic runoff (2 to 3 vessels) had a markedly higher 5-year patency rate (70%) than the poor arteriographic runoff (0 to 1 vessels) group (30%). Continued cigarette smoking and diabetes mellitus also appeared to affect adversely primary graft patency in our hands. Our data support the use of preferential above-knee expanded polytetrafluoroethylene grafts in patients with good angiographic runoff. This approach does not appear to prejudice the limb against secondary revisionary procedures or the use of a new autogenous graft, if required.

Adult↗

PubMed1989

Long-term follow-up of surgically managed carotid bifurcation atherosclerosis. Justification for an aggressive approach.

To document the efficacy of our aggressive surgical approach to stroke prevention, we compiled follow-up data on 619 patients undergoing 993 carotid endarterectomies at our institution since 1970. Following carotid endarterectomy, crude annual stroke incidence, including perioperative strokes (2.2%), was 1.9%. In our symptomatic patients crude annual stroke incidence, including perioperative strokes (2.7%), was 2.1%. This is superior to the annual stroke incidence seen in patients on "optimal" medical therapy as defined by the Canadian Cooperative Study (4.6% in men), the AICLA Study (2.9%), the American Multicenter Trial (8%), and the Canadian- American Cooperative Trial (approximately 5%). In our asymptomatic patients, crude annual stroke incidence, including perioperative strokes (1.1%), was 1.4%. This is superior to nonsurgical therapy for asymptomatic patients with hemodynamically significant or more than 75% stenoses as reported by the Mayo Clinic (3.4%) or Chambers and Norris (2.7%). An aggressive surgical approach to carotid bifurcation atherosclerosis is superior to nonsurgical therapy in symptomatic and selected asymptomatic patients if low perioperative mortality/stroke morbidity rates are achieved.

Actuarial Analysis↗

PubMed1989

Observations of Japanese men and children in public places: a comparative study.

The popular image of Japanese men, both in the United States and Japan, is that of "salaryman" who works such long hours that he has no time left for his children. The little empirical evidence available, however, suggests that Japanese men have familial involvement patterns not unlike those of men in the United States. In the study reported here, prepubertal children and adult males in Japan and the USA were observed together disproportionately more often during those times when men were not precluded (by work) from being with children. Further, during those periods children were more likely to be found in groups containing men rather than with women only. In both countries women continue to be the primary caregivers of children. However, previous research has shown that men in the USA, compared to men in other cultures, are not totally uninvolved; Japanese men are not either.

Adult↗

PubMed1989

Carotid endarterectomy in patients with intracranial vascular disease: short-term risk and long-term outcome.

To determine the influence of angiographically identifiable intracranial vascular lesions on the outcome of carotid endarterectomy, 597 patients from our carotid surgery registry who had had complete angiographic evaluation were divided into two groups: (1) significant intracranial disease identified by angiography (N = 134) and no significant intracranial disease identified by angiography (N = 463). The short- and long-term outcomes of carotid endarterectomy in the two groups were compared. Perioperative stroke morbidity (intracranial disease 1.9%, no intracranial disease 1.8%) and mortality (intracranial disease 0.5%, no intracranial disease 0.7%) were acceptable and not statistically different (p greater than 0.7). Late stroke prevention was nearly identical in the two groups, with 3-, 5-, and 10-year life-table of stroke-free rates of 93%, 87%, and 79%, respectively, versus 92%, 90%, and 85%, respectively, in the intracranial disease and no intracranial disease groups (p = 0.75). The incidence of recurrent transient ischemic attack was 9.7% in the intracranial disease group and 6.5% in the no intracranial disease group (p = 0.22). In the clinical population studied in the described method, angiographically identifiable intracranial vascular disease did not appear to have a statistically demonstrable influence on the short-term or long-term prognosis after carotid endarterectomy.

Brain Ischemia↗

PubMed1988

Correlation of clinical findings with venous hemodynamics in 386 patients with chronic venous insufficiency.

Deep venous insufficiency secondary to deep valvular incompetence predominated over superficial venous insufficiency in an unselected patient population with advanced chronic venous insufficiency. Venous obstruction was uncommon (5 percent), suggesting that venous bypass surgery may have limited applicability in the management of chronic venous insufficiency. Although the majority of patients (72 percent) with stage III venous disease (ulcer) had deep venous insufficiency alone and would be potential candidates for deep valvular reconstruction, 13 percent were found to have superficial venous insufficiency alone, and the remaining 15 percent, deep venous insufficiency with a hemodynamically significant component of superficial venous insufficiency. These findings suggest that not all patients with stage III disease have altered hemodynamics on the basis of deep venous valvular incompetency. Although most stage III chronic venous insufficiency is secondary to altered deep venous hemodynamics, as demonstrated by shortened venous refill time, there is a significant group of patients with severe chronic venous insufficiency having superficial venous insufficiency alone or in combination with deep venous insufficiency (28 percent). Thus, it is imperative that those patients with superficial venous insufficiency be identified by a widely available and reproducible method, such as light reflection rheography, since they may respond to surgery of the superficial venous system alone.

Adolescent↗

PubMed1988

Hemodynamics and prostacyclin release in the early phases of aortic surgery: comparison of transabdominal and retroperitoneal approaches.

Although the retroperitoneal aortic approach (RP) is advocated to reduce myocardial ischemia and cardiac-related death, inadequate physiologic data exist to support this contention. As the aorta is exposed via the transabdominal approach (TA) we noted some patients have manifested reduced systemic vascular resistance (SVR) associated with tachycardia, reduced blood pressure, and facial flushing. To determine whether RP offered physiologic advantages over TA we compared cardiac dynamics and blood levels of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), the stable metabolite of prostacyclin, during exposure of the aorta in 52 patients (33 with TA and 19 with RP), comparable in age, cardiac history, medications, and body surface area. Serial measurements of mean arterial pressure, heart rate, wedge pressure, pulmonary artery pressure, cardiac index, and 6-keto-PGF1 alpha were obtained. Results revealed decreased mean arterial pressure and systemic vascular resistance, increased cardiac index and heart rate, and facial flush occurring 10 minutes after the bowel was explored in TA. This was not observed in RP. These hemodynamic alterations correlated in time and magnitude with a fourteen fold increase in 6-keto-PGF1 alpha. These changes in cardiac indexes can produce increased myocardial oxygen consumption with the risk for myocardial ischemia, particularly in patients with coronary artery disease. The absence of this response to bowel exploration in RP may account for some of the observed advantages in "high-risk" aortic reconstruction.

6-Ketoprostaglandin F1 alpha↗

PubMed1987

Treatment of calcific aortic stenosis by balloon valvuloplasty.

Recent reports have established the feasibility of using balloon valvuloplasty to reduce left ventricular outflow tract obstruction due to a calcified aortic valve. The present study summarizes experiences with this technique in 9 patients (7 women, 2 men, mean age 78 years) in whom balloon valvuloplasty was used to treat calcific aortic stenosis. Peak aortic valve gradient (mm Hg) decreased from 68 +/- 8 (mean +/- standard error of the mean) before valvuloplasty to 35 +/- 5 after valvuloplasty (p = 0.003). Mean aortic valve gradient decreased from 57 +/- 7 before valvuloplasty to 30 +/- 5 after valvuloplasty (p = 0.006). Calculated aortic valve area increased from 0.42 +/- 0.04 to 0.81 +/- 0.06 cm2 (p = 0.005). Balloon valvuloplasty failed to diminish aortic valve obstruction in only 1 patient who, at subsequent surgery, had a congenitally bicuspid aortic valve. Significant aortic regurgitation was not observed in any of the 9 patients after valvuloplasty. One patient did have a highly focal, presumably embolic, brain stem infarct during the procedure. Femoral arterial blood loss, related to wire-guided exchange of balloon catheters too large for a 12Fr introducer sheath, was minimized by direct arterial exposure in 8 of the 9 patients. Thus, these findings confirm the efficacy of balloon valvuloplasty for the treatment of calcific aortic stenosis. The procedure, however, is not without hazard.

Aged↗

PubMed1987

Clinical, hemodynamic, and anatomic follow-up of direct venous reconstruction.

Conventional therapy for the advanced clinical stages of the postthrombotic syndrome is associated with recurrence of symptoms and ulcer. Direct venous reconstruction may relieve the symptoms of patients with either iliac vein obstruction or valvular incompetence, but there are few reports detailing late hemodynamic and anatomic findings. We summarized the clinical, hemodynamic, and anatomic follow-up of six patients with saphenofemoral bypass (SFB) and ten patients with axillary vein valve-to-popliteal vein transplants (PVTs) who were followed up for a minimum of two years. All ten ulcers in the PVT group healed and symptoms of venous claudication, limb swelling, and all ulcers healed in the SFB group. Late (greater than 2 years) anatomic and functional assessment showed that the SFB bypasses were patent and the PVTs were both patent and functional.

Adult↗

PubMed1987

The management of early in situ saphenous vein bypass occlusions.

To determine the causes and optimum management of early in situ bypass occlusions, we reviewed our experience of 13 thromboses occurring within the first 30 postoperative days in 148 in situ saphenous vein reconstructions. All early thrombosed bypasses were performed for limb salvage, with 31% of bypasses to the popliteal level and 69% to infrapopliteal vessels. The median time to occlusion was 24 hours. All patients underwent reoperation. Graft failure was due to retained venous valves in 31% of the procedures, other technical problems in 38%, and inadequate outflow in 31%. Reoperative surgery was individualized. In grafts explored for thrombosis, the one-year graft patency rate was 46%, and the limb salvage rate was 54%. Graft patency did not appear to correlate with the presumed cause of initial graft occlusion. Our results indicate that an aggressive surgical approach is appropriate in early in situ graft thrombosis.

Humans↗

PubMed1987

The effect of low molecular weight dextran on platelet deposition onto prosthetic materials.

Low molecular weight dextran (LMD) has recently been shown in a randomized, multicenter trial to improve early patency in difficult lower extremity vascular bypass. The question remained as to whether this effect was due to plasma volume expansion by LMD or to its effects on platelets and coagulation. To analyze this we have studied the effects of LMD on platelet-graft interactions using an ex vivo baboon shunt. Indium 111-labeled autologous platelet deposition on expanded polytetrafluoroethylene and knitted Dacron grafts was monitored at a flow rate of 25 ml/min for 21/2 hours. LMD was given by intravenous bolus at a dose of 5 ml/kg and was followed by a continuous infusion of 10 ml/hr. Flow through the shunt was started after the initial dextran bolus. Control studies were performed in a similar manner without dextran. An additional series of experiments was performed with a 5 to 10 ml/kg bolus of 5% human serum albumin to analyze the contribution of plasma volume expansion to platelet deposition in this model. The results revealed a significant (p less than 0.05) reduction in platelet deposition on both graft materials with the LMD infusion. No difference was seen between the control group and the albumin group. These studies provide direct in vivo evidence of the antiplatelet effect of LMD.

Albumins↗

PubMed1986

Retroperitoneal approach to high-risk abdominal aortic aneurysms.

During a 14-month period we used a left-flank, retroperitoneal, retrorenal approach in 23 high-risk patients with abdominal aortic aneurysm (AAA). Fourteen patients underwent suprarenal/celiac cross clamp for juxtarenal/suprarenal AAA and/or associated occlusive disease. Other indications for this approach included diminished cardiac and/or pulmonary reserve, previous extensive abdominal surgery, obesity, and inflammatory AAA. There was only one death (4%) in this high-risk group and minimal operative morbidity. The flexibility afforded by this approach for high aortic exposure allowed expeditious proximal anastomoses with minimal postoperative renal dysfunction. Pulmonary complications, ileus, and pain were reduced and patient mobilization was rapid despite the complex nature of the operative procedures. We believe that this approach offers significant advantages for all cases of AAA but particularly for anatomically complex lesions and medically high-risk patients.

Aged↗

PubMed1986

Antiplatelet therapy and vascular grafts. Studies in a baboon ex vivo shunt.

Antiplatelet therapy is currently recommended in an effort to improve patency rates of small-caliber vascular grafts. The effect of aspirin and heparin on acute platelet deposition was studied in a baboon ex vivo shunt. Two grafts, expanded polytetrafluoroethylene and knitted Dacron, were exposed to a flow rate of 25 mL/min after administration of aspirin or heparin. Indium 111-labeled platelet uptake by the grafts was determined over 2 1/2 hours. The amount of platelet deposition in the treated groups was significantly less than that of controls after 2 1/2 hours. There was no difference between the aspirin and heparin groups. The finding that heparin inhibited platelet deposition to a degree comparable with aspirin suggests that it may not be necessary to start antiplatelet therapy preoperatively. Intraoperative systemic heparinization will provide sufficient inhibition of platelet deposition. A protocol for perioperative antiplatelet therapy is outlined.

Animals↗

PubMed1986

Endothelial cell seeding of small-caliber synthetic grafts in the baboon.

Endothelial cell (EC) seeding has been proposed as a method to improve the performance of small-caliber synthetic vascular prostheses. Seeding experiments to date have all been carried out in the dog. This study investigates EC seeding of small-caliber Dacron carotid interposition grafts compared with contralateral control grafts in the baboon. Surface thrombogenicity was assessed at 24 hours, 2 weeks, and 4 weeks after implantation with indium 111-labeled autologous platelets. Morphologic and immunohistochemical techniques were used to assess the identity and homogeneity of the EC inoculum before seeding and to identify cell types on the harvested grafts. There was no significant difference in patency rates between seeded and control grafts at 5 weeks. Platelet accumulation on seeded grafts was significantly less (p less than 0.05) than on paired controls at 2 and 4 weeks after implantation. The luminal lining of seeded grafts had more cellular ingrowth, less adherent thrombus, and more surface cells with the morphologic and histochemical characteristics of EC than did the lining of controls. EC seeding reduces the platelet reactivity and accelerates EC coverage of small-caliber grafts in the baboon.

Animals↗

PubMed1986

The costs of surgery for limb-threatening ischemia.

The clinical courses of 106 patients with limb-threatening ischemia were traced for as long as 5 years to determine the cost of their care. Seventy-eight patients initially treated with vascular reconstruction accrued an average of $40,769 +/- $3726 in costs over a mean follow-up period of 805 +/- 57 days, during which they had an average of 2.4 +/- 0.2 hospitalizations or 67 +/- 6 inpatient days. Twenty-eight high-risk patients treated with primary amputation accrued $40,563 +/- $4729 in costs over a mean follow-up period of 663 +/- 97 days, during which they had an average of 2.2 +/- 0.3 hospitalizations or 85 +/- 10 inpatient days. Successful revascularization resulted in lower costs ($28,374) than did primary amputation ($40,563) or failed reconstruction ($56,809). Patients with ischemic tissue loss accrued costs more rapidly than did patients with rest pain only. The high cost of providing care for these patients and the advent of diagnosis related group reimbursement mandate that proposed treatment protocols be evaluated not only for their effectiveness but also for their cost-effectiveness.

Actuarial Analysis↗

PubMed1985

Correlation of B-mode ultrasound imaging and arteriography with pathologic findings at carotid endarterectomy.

Presently most noninvasive methods for assessing extracranial carotid disease have relied on hemodynamic change associated with significant stenosis. Recent evidence has suggested that both ulceration and/or plaque hemorrhage may frequently play an important role in the pathophysiology of carotid disease. To assess the ability of B-mode ultrasound to provide this anatomic information, in a prospective blinded manner we compared B-mode ultrasound and selective four-vessel arteriography to pathologic specimens obtained at the time of 89 carotid endarterectomies. The presence of ulceration, plaque characteristics (particularly hemorrhage), and luminal diameter were described for each modality. While arteriography detected only 16 of 27 ulcerations (sensitivity, 59%), B-mode ultrasound had a greater sensitivity (24/27, 89%). Both modalities had comparable specificities (arteriography, 73%; B-mode ultrasound, 87%). Moreover, B-mode ultrasound was highly sensitive for demonstrating plaque hemorrhage (27/29, 93%), as well as being quite specific (84%). Assessment of luminal reduction by B-mode ultrasound improved with technologist/interpreter experience and was significantly improved by adding real-time spectral analysis. Because of B-mode ultrasound's sensitivity for imaging ulceration and plaque hemorrhage, it offers significant advantages for the noninvasive detection of extracranial carotid disease.

Arterial Occlusive Diseases↗

PubMed1985

Evaluation of arterial prostheses in a baboon ex vivo shunt: the effect of graft material and flow on platelet deposition.

Surface thrombogenicity is recognized as an important factor in the failure of small caliber vascular prostheses. The baboon ex vivo shunt was developed to study small caliber grafts under controlled conditions at different flow rates. The shunt was created by percutaneous insertion of catheters into the baboon femoral artery and vein. Platelet-graft interactions were studied using autogenous indium 111 labeled platelets. Two graft materials were placed in series and exposed to blood flow for 2 1/2 hours at flow rates of 25 and 200 ml/min. At the end of this period, the grafts were removed for morphologic examination. Platelet adhesion to the grafts, especially with the less thrombogenic materials (PTFE and HUV), was found to be independent of flow rate. PTFE was found to be the least platelet-reactive material, HUV was intermediate, and knitted Dacron was the most thrombogenic surface. Platelet deposition on the flow surface was confirmed by light microscopy and scanning electron microscopy.

Animals↗