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J B Towne

Publications and source records attributed to J B Towne.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cholesterol, but not cigarette smoke, decreases rabbit carotid artery relaxation.

The purpose of this study was to determine the physiologic effects of cigarette smoke exposure and dietary cholesterol on the availability of nitric oxide in carotid vascular rings. New Zealand white rabbits were placed in an airflow chamber for 3 hr/day over an 8-week period and were exposed to smoke from 600 cigarettes/per day added to the chamber inflow by a robotic smoke generator. New Zealand white rabbits, made hypercholesterolemic, and one group fed a normal diet, were similarly placed in the chamber without exposure to cigarette smoke. In those exposed groups, serum cotinine and cholesterol levels were consistently elevated. After the 8-week period, the carotid arteries were harvested. The vessels were cut into 3-mm rings which were suspended from pressure transducers. The rings were contracted with potassium chloride (KCl) to determine vessel integrity. One ring from each carotid was maximally contracted with 1 x 10(-3) molar norepinephrine (NE) while the experimental ring was contracted to 50% of maximum. Relaxation of the rings was achieved by adding incremental doses of acetylcholine. Our results showed that endothelial dysfunction, as measured by acetylcholine-mediated vasorelaxation, occurs in the rabbit carotid artery when exposed to high dietary cholesterol. Cigarette exposure alone in this particular vessel did not result in significant alteration in acetylcholine-mediated vasorelaxation.

Acetylcholine↗
PubMed1999

Endovascular therapy of iliac arteries: routine application of intraluminal stents does not improve clinical patency.

Our objective in this study was to review our experience with endovascular therapy of iliac artery occlusive disease over the past decade, and to compare the results of angioplasty alone with the addition of endovascular stents to these procedures. This report details a retrospective analysis of clinical data on 141 consecutive patients with iliac artery occlusive disease, treated by balloon angioplasty alone, or with the addition of intraluminal stents. The procedures analyzed included 58 common iliac artery interventions (26 angioplasties and 32 stent insertions) and 83 external iliac artery procedures (43 angioplasties and 40 stent insertions). Early and continued success, and their components, are reported and compared according to published standards. While endovascular therapy of iliac artery occlusive disease is effective in relieving symptoms, clinical patency rates are lower than those reported for direct reconstruction. Primary stent placement has not enhanced clinical patency in the iliac arteries, and the selective insertion of these devices for more complicated angioplasty procedures seems warranted.

Adult↗
PubMed1999

Women have increased risk of perioperative myocardial infarction and higher long-term mortality rates after lower extremity arterial bypass grafting.

PURPOSE: The purpose of this study was to determine the effect of gender on the immediate and long-term postoperative morbidity, mortality, and patency rates for infrainguinal autogenous vein bypass grafts. METHODS: Data were abstracted for consecutive patients who were followed in a prospective surveillance protocol after undergoing infrainguinal autogenous vein bypass grafting during the years 1988 to 1994. There were 165 grafts constructed in 148 patients (101 in 87 men, and 64 in 61 women). Gender differences were analyzed with Student t test or chi2 test for risk factors, indications for reconstruction, and complications. The patency rates and the long-term survival rates were compared by means of life-table analysis. Eagle criteria and long-term survival rates were compared with multivariate analysis. RESULTS: The mean follow-up period was 36 months (39 months for men, and 32 months for women), with a range of 6 to 123 months for the total follow-up period. The two groups did not differ in age at the time of operation (66.6 +/- 1.2 years for men, and 66.7 +/- 1.5 years for women) or in history of diabetes (48% for men, and 56% for women). The risks were similar for hypertension (48% for men vs 45% women), preoperative myocardial infarction (23% for men vs 26% for women), and previous coronary artery bypass grafting (9% for men vs 8% for women). The thallium stress scintigraphy results showed a diagnosis of proportionately more preoperative defects in men (reversible, 34% vs 18%, P <.05; overall, 75% vs 43%, P <.05). The 30-day limb loss rates (0.9% for men, and 0% for women) and mortality rates (2.2% for men, and 5% for women) were similar. Women had statistically more perioperative myocardial infarctions than did men (6 of 61, 9.8% vs 2 of 101, 2%; P <.05), as was documented with electrocardiography and cardiac isoenzymes. Two of these women died within a 30-day postoperative period. The 3-year primary patency rate was 85% for the men and 88% for the women, and the primary assisted patency rate was 97% for the men and 97% for the women. The secondary patency rate was 98% for the men and 97% for the women. The limb salvage rate was slightly higher for the men than for the women (93% vs 87%), although this was not statistically significant. The 5-year survival rate for women was statistically less than for men, with life-table analysis (58% for men vs 42% for women; P <.05). CONCLUSION: After distal bypass grafting, men and women have similar rates of patency and limb salvage, but women have a higher incidence rate of perioperative myocardial infarction and a decreased 5-year survival rate. These data suggest that women have unrecognized cardiac disease that affects them adversely in the perioperative period and the long term when compared with men who undergo the same operation.

Aged↗
PubMed1999

Health-related quality of life and functional outcome following arterial reconstruction for limb salvage.

Vascular surgery outcomes have traditionally been measured by limb salvage and graft patency. However, as health care resources are rationed, the patient's functional outcome and quality of life will require assessment. The in situ saphenous vein graft has proven successful in achieving long-term limb salvage for patients with critical ischemia, with the expectation of preserving a life-style and sense of well-being that would be lost with limb amputation. This study was conducted to measure functional capacity and quality of life in these patients. Seventy patients with successful in situ saphenous vein bypass grafts constructed for limb-threatening ischemia, followed for a mean of 45.6 months in a surveillance program with normal graft flow characteristics, were compared with a group of age and gender-matched controls with normal limb pressures and no history of vascular occlusive disease. A questionnaire was designed from standardized health status scales and administered to the two groups to assess symptoms, health perceptions, physical functioning and life quality. When comparing the groups of revascularized and control patients, symptoms and perceptions about their health were similar. However, the revascularized patients had significantly decreased functional capacity in their ability to walk various distances (P< or =0.005), perform household tasks (P< or =0.001) and bathe (P< or =0.001). The patient group with vascular grafts functioned as well as the controls only in activities of dressing and using the toilet. Indicators of life quality that rate independence and mobility, including the ability to procure groceries (P< or = 0.001), prepare meals (P< or =0.005) participate in social activities (P< or =0.001) and drive an automobile (P< or =0.01), were also significantly limited in the patients with successful vascular reconstructions. Although achieving long-term limb salvage and graft patency, the patients in this group of successful vascular reconstructions retain functional disabilities that require significant care. Despite these physical handicaps, these patients have a remarkably similar sense of well-being and lack of somatic complaints compared with the control group. This medical outcome study identifies the functional capacity and lifetime needs for vascular surgery patients that will provide useful data for those responsible for allocating health care resources.

Activities of Daily Living↗
PubMed1998

Tissue inhibitor of metalloproteinase-1 is increased in the saphenofemoral junction of patients with varices in the leg.

PURPOSE: The goal of the present study was to examine the role of matrix metalloproteinase (MMP) activity in the development of varicose changes in the superficial veins of the lower extremity. METHODS: Normal-caliber vein segments from the saphenofemoral junction were harvested from patients undergoing saphenous vein ligation for varices and from patients undergoing infrainguinal bypass graft procedures. The activity and quantity of MMPs and their inhibitors (tissue inhibitors of metalloproteinases [TIMPs]) in the vein segments were compared. Vein segments were obtained from 13 patients. Seven patients had varicose disease in the leg, including 6 women and 1 man (average age, 48 years). Six patients had no evidence of varicose disease, including 2 women and 4 men (average age, 59 years). Proteolytic activity was determined with substrate gel zymography, and enzyme content was determined with Western immunoblotting using monoclonal antibodies directed against MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, and alpha2-macroglobulin. Signals were quantified by scanning densitometry and normalized to a positive control (densitometric index [DI]). Immunohistochemistry was performed for enzyme localization. RESULTS: Zymography did not detect a difference between groups at loci consistent with the major MMPs; however, a small but significant decrease in proteolytic activity was noted in veins from patients with varices. TIMP-1 is increased in vein segments from patients with varices (DI 0.8 +/- 0.1 vs 0.2 +/- 0.05, P < .05) while MMP-2 levels were decreased (DI 1.5 +/- 0.3 vs 0.5 +/- 0.1, P < .05). Immunohistochemistry localized MMPs to the adventitia of the vein wall. CONCLUSION: A decrease in proteolytic activity may be responsible for the histological and structural alterations leading to varicose degeneration of superficial lower extremity veins.

Blotting, Western↗
PubMed1998

Endothelial damage due to ischemia and reperfusion is prevented with SIN-1.

BACKGROUND: Acute ischemia followed by reperfusion results in direct endothelial damage characterized by cell swelling, increased permeability and loss of acetylcholine-mediated vasorelaxation. Ischemia followed by reperfusion in a New Zealand white rabbit hindlimb has been shown to result in loss of acetylcholine-induced relaxation of superficial femoral arteries. This loss of relaxation in response to acetylcholine is a reflection of the decreased nitric oxide availability that occurs with reperfusion injury. The purpose of this investigation was to evaluate the effect of SIN-1, a direct nitric oxide donor, on this endothelial injury. METHODS: New Zealand white rabbits underwent complete ischemia of the right hindlimb for 3 h followed by 2 h of reperfusion. Aliquots of 20 ml of either 0.88-mM SIN-1 or normal saline was infused via a lateral branch of the right common iliac artery during the first 20 min of reperfusion. Sham vessels were subjected to the 5-h operative intervention to control for anesthetic effect. Control vessels were harvested from rabbits not exposed to ischemia or reperfusion. Superficial femoral artery rings were evaluated in vitro for endothelial cell-mediated relaxation. Rings were contracted with potassium chloride and norepinephrine and then exposed to standardized incremental doses of acetylcholine to measure percent relaxation. Artery sections were sent for hematoxylin and eosin staining. RESULTS: No significant differences were seen in contraction caused by either potassium chloride or norepinephrine in all four experimental groups. Saline infused vessel rings relaxed a mean of 8.42 +/- 2.39% and 49.57 +/- 8.65% in response to acetylcholine doses of 3 x 10(-8) M and 1 x 10(-7) M, respectively. In contrast, SIN-1 infused vessels relaxed a mean of 57.82 +/- 2.65% and 100.23 +/- 1.53% to the same doses of acetylcholine. Control and sham arteries showed a similar relaxation response as compared with SIN-1 infused vessels. Differences in relaxation when comparing saline infused vessels with SIN-1 infused, sham and control arteries, were significantly different at each dose of acetylcholine from 3 x 10(-8) M to 1 x 10(-7) M (P < 0.05, ANOVA). Histologic examination of the vessels revealed no morphologic differences among the experimental groups. All vessels were structurally normal with an intact endothelium. CONCLUSION: In this model of rabbit hindlimb ischemia, preservation of endothelial cell-mediated vasorelaxation occurs with administration of intra-arterial SIN-1 during reperfusion. This preservation of endothelial function cannot be explained by histologic changes in the arterial wall or attributed to altered arterial contractility in response to potassium chloride or norepinephrine.

Animals↗
PubMed1998

Endothelial damage due to ischemia and reperfusion is prevented with SIN-1.

BACKGROUND: Acute ischemia followed by reperfusion results in direct endothelial damage characterized by cell swelling, increased permeability and loss of acetylcholine-mediated vasorelaxation. Ischemia followed by reperfusion in a New Zealand white rabbit hindlimb has been shown to result in loss of acetylcholine-induced relaxation of superficial femoral arteries. This loss of relaxation in response to acetylcholine is a reflection of the decreased nitric oxide availability that occurs with reperfusion injury. The purpose of this investigation was to evaluate the effect of SIN-1, a direct nitric oxide donor, on this endothelial injury. METHODS: New Zealand white rabbits underwent complete ischemia of the right hindlimb for 3 h followed by 2 h of reperfusion. Aliquots of 20 ml of either 0.88-mM SIN-1 or normal saline was infused via a lateral branch of the right common iliac artery during the first 20 min of reperfusion. Sham vessels were subjected to the 5-h operative intervention to control for anesthetic effect. Control vessels were harvested from rabbits not exposed to ischemia or reperfusion. Superficial femoral artery rings were evaluated in vitro for endothelial cell-mediated relaxation. Rings were contracted with potassium chloride and norepinephrine and then exposed to standardized incremental doses of acetylcholine to measure percent relaxation. Artery sections were sent for hematoxylin and eosin staining. RESULTS: No significant differences were seen in contraction caused by either potassium chloride or norepinephrine in all four experimental groups. Saline infused vessel rings relaxed a mean of 8.42 +/- 2.39% and 49.57 +/- 8.65% in response to acetylcholine doses of 3 x 10(-8) M and 1 x 10(-7) M, respectively. In contrast, SIN-1 infused vessels relaxed a mean of 57.82 +/- 2.65% and 100.23 +/- 1.53% to the same doses of acetylcholine. Control and sham arteries showed a similar relaxation response as compared with SIN-1 infused vessels. Differences in relaxation when comparing saline infused vessels with SIN-1 infused, sham and control arteries, were significantly different at each dose of acetylcholine from 3 x 10(-8) M to 1 x 10(-7) M (P < 0.05, ANOVA). Histologic examination of the vessels revealed no morphologic differences among the experimental groups. All vessels were structurally normal with an intact endothelium. CONCLUSION: In this model of rabbit hindlimb ischemia, preservation of endothelial cell-mediated vasorelaxation occurs with administration of intra-arterial SIN-1 during reperfusion. This preservation of endothelial function cannot be explained by histologic changes in the arterial wall or attributed to altered arterial contractility in response to potassium chloride or norepinephrine.

Animals↗
PubMed1997

Pentoxifylline prevents endothelial damage due to ischemia and reperfusion injury.

BACKGROUND: Endothelial injury after ischemia and reperfusion is characterized by an increase in permeability, cellular edema, and loss of acetylcholine-mediated vasorelaxation. Three hours of ischemia followed by 2 hr of reperfusion in the New Zealand white rabbit hindlimb has been shown to result in loss of acetylcholine-induced superficial femoral artery vasorelaxation. The purpose of this study was to evaluate the effect of intraarterial pentoxyfylline (PTX) on this endothelial injury. METHODS: New Zealand white rabbits underwent 3 hr of complete hindlimb ischemia followed by 2 hr of reperfusion. Twenty milliliters of either 100 microM PTX or normal saline was infused over 20 min via the circumflex iliac artery at initiation of reperfusion. Superficial femoral artery rings were then evaluated in vitro for endothelial cell-mediated relaxation. Rings were exposed to standardized incremental doses of acetylcholine after norepinephrine-induced contraction and percentage relaxation was measured. Sections of arteries were also sent for hematoxylin and eosin staining. RESULTS: Similar contraction responses following NE stimulation were observed between control and PTX-treated rings. Control rings relaxed a mean of 14.97 +/- 3.64, 23.17 +/- 5.61, and 31.84 +/- 8.43% in response to acetylcholine doses of 6 x 10(-8), 1 x 10(-7), and 1.5 x 10(-7) M, respectively. In contrast, PTX-treated segments relaxed a mean of 47.52 +/- 8.88, 62.32 +/- 6.83, and 76.73 +/- 4.91% to the same doses of acetylcholine. Differences in relaxation between control and PTX-treated vessels were significantly different at each dose (P < 0.05, Student's t test). Histologic examination of the PTX-treated and control arteries revealed an intact endothelium without morphologic differences between the two groups. CONCLUSION: In this model of rabbit hindlimb ischemia, endothelial cell-mediated vasorelaxation was preserved with the administration of intraarterial PTX during reperfusion compared to controls. The different relaxation responses could not be attributed to altered arterial contractility in response to norepinephrine, or explained by histologic changes in the arterial wall. These studies demonstrate a potential modality for therapeutic intervention to reduce reperfusion injury after acute limb ischemia.

Acetylcholine↗
PubMed1997

Duplex morphologic features of the reconstructed carotid artery: changes occurring more than five years after endarterectomy.

PURPOSE: To determine the late morphologic appearance of the carotid artery after endarterectomy and to relate the morphologic characteristics to the development of recurrent carotid stenosis and subsequent neurologic symptoms. METHODS: Eighty-eight carotid reconstructions (51% included patch angioplasty) in 82 patients were studied 5 or more years after carotid endarterectomy. Duplex color flow imaging was used to determine morphologic characteristics of the carotid endarterectomy site and to document the occurrence, time interval, and progression of recurrent internal carotid artery stenosis. The spatial orientation of recurrent wall thickening, presence of calcium, arterial wall texture, and presence of laminar flow were evaluated. Recurrent stenoses were categorized using standard duplex criteria. RESULTS: The mean duration of follow-up was 99 months (range, 60 to 138 months). Arterial wall calcium was identified in 23% (n = 18), a smooth luminal surface in 57% (n = 46), and laminar flow in 52% (n = 42). Recurrent wall thickening developed in 58 vessels (66%), involving the posterior segment of the vessel in 95%, and anterior, lateral, or medial aspects in 24% (n = 14). Restenosis > 50% diameter reduction occurred in 4% of common carotid arteries (n = 3) and in 15% of internal carotid arteries (n = 13). Ten of the internal carotid artery restenoses occurred after a mean of 76 months (range, 13 to 132 months), and the three remaining patients had asymptomatic occlusions after a mean of 61 months (range, 1 to 96 months). Neurologic events referable to the reconstructed carotid artery occurred in three patients at a mean of 77 months; two were a result of recurrent carotid disease. One symptomatic patient and two asymptomatic patients (3.7%) underwent a second ipsilateral reconstruction for recurrent high-grade stenosis. CONCLUSIONS: The carotid artery remains smooth, with laminar flow and without calcification, in the majority of reconstructions that were observed over a long term. There is a low incidence of subsequent ipsilateral neurologic events or significant recurrent stenosis, both of which usually occur late in the postoperative period. This study documents the long-term durability of carotid endarterectomy in providing risk reduction for stroke.

Aged↗
PubMed1997

Combined exposure to cigarette smoke and hypercholesterolemia decreases vasorelaxation of the aorta.

PURPOSE: The purpose of this study was to determine the physiologic effects of cigarette smoke exposure and dietary cholesterol on the availability of nitric oxide in aortic vascular rings. METHODS: Four groups of New Zealand White rabbits were placed in an air flow chamber for 3 hours per day for 8 weeks. Two of these groups were exposed to smoke from 600 cigarettes per day 5 days a week added to the chamber inflow by a robotic smoke generator. One of these groups was made hypercholesterolemic by being fed a 0.3% cholesterol diet. Two groups of rabbits were similarly placed in the air flow chamber but without smoke exposure, of which one group was also made hypercholesterolemic. After an 8-week period, the rabbits were killed and the infrarenal aortas were excised. The vessels were cut into 3 mm rings and suspended from tension transducers. The rings were contracted with potassium chloride to determine vessel integrity. Then one ring from each aorta was maximally contracted with norepinephrine, and the experimental ring was contracted to 50% of maximum. Relaxation of the rings in response to incremental doses of acetylcholine was measured. RESULTS: No significant differences were seen in contraction to potassium chloride or norepinephrine in any group. A significant decrease in acetylcholine-mediated relaxation was seen only in the smoke-exposed, cholesterol-fed group. CONCLUSIONS: Endothelial damage, as measured by acetylcholine-mediated vasorelaxation, occurs in the infrarenal aorta in rabbits that are exposed to both cigarette smoke and elevated dietary cholesterol. Cigarette smoke exposure alone or hypercholesterolemia alone in this model did not result in significant alteration in acetylcholine-mediated vasorelaxation.

Acetylcholine↗
PubMed1996

Loss of superficial femoral artery relaxation following ischemia-reperfusion.

Acute ischemia followed by reperfusion in skeletal muscle is associated with tissue edema and necrosis. The purpose of this study was to demonstrate superficial femoral artery endothelial injury following complete ischemia with reperfusion. New Zealand white rabbits underwent total devascularization of one hindlimb for 3 hr followed by 0, 1, and 2 hr of reperfusion. Control rabbits underwent a sham operation. Superficial femoral artery rings were then studied for acetylcholine induced relaxation in vitro. The response to acetylcholine was measured as percentage relaxation at three incremental doses (1 x 10(-7) , 3 x 10(-7) and 5 x 10(-7) M). The ischemia-only (26.30 +/- 7.07, 62.63 +/- 8.64, 88.08 +/- 5.25%) and the 1-hr reperfusion group (19.35 +/- 12.99, 39.24 +/- 15.78, 62.01 +/- 14.03%) showed no significant difference (P > or = 0.05, Student's t test) in relaxation as compared to the control group (13.73 +/- 2.11, 47.88 +/- 7.23, 72.44 +/- 9.00%). The 2-hr reperfusion group (6.10 +/- 1.02, 15.33 +/- 2.56, 34.67 +/- 6.31%), however, had a significant loss of relaxation at all three doses of acetylcholine compared to that seen in the control group (P < or = 0.05, Student's t test). In this model of complete ischemia, superficial femoral artery rings lose their ability to relax in response to acetylcholine following 3 hr of ischemia and 2 hr of reperfusion, demonstrating endothelial injury. However, immediately after 3 hr of ischemia or ischemia followed by only 1 hr of reperfusion, superficial femoral artery rings did not lose their ability to relax in response to acetylcholine. This study identifies a window of opportunity for therapeutic intervention after ischemia and prior to endothelial injury from reperfusion.

Animals↗
PubMed1996

Using dipyridamole-thallium imaging to reduce cardiac risk in aortic reconstruction.

UNLABELLED: Cardiac morbidity and mortality remain the major operative risk following aortic reconstruction (AR) performed for aneurysmal and occlusive disease. We reviewed the preoperative cardiac evaluation and outcome in 209 patients who had AR between 1987 and 1992. Dipyridamole-thallium stress test (DTST) was performed in 147 (70.3%) patients. Fifty-six of these patients had a normal DTST and only 1 (1.8%) had a perioperative myocardial infarction (MI). Forty-six patients had a fixed defect on their DTST and 3 (6.5%) had perioperative MI. Forty-five patients had reversible defects on their DTST and 2 (4.4%) had perioperative MI with 1 cardiac death. Following DTST, 29 coronary catheterizations were performed. Ten catheterizations were normal or had minimal one-vessel coronary artery disease with an associated postoperative death in 1 patient due to cardiac dysrhythmia. Nineteen patients had abnormal coronary angiography, 1 of whom had a perioperative myocardial infarction and 5 of whom underwent coronary artery revascularization (CABG) (3) or percutaneous transluminal angioplasty (2) prior to AR without subsequent cardiac events. Forty-three (20.6%) had either no cardiac symptoms (40) or prior CABG (3) precluding invasive cardiac evaluation. There was one fatal perioperative myocardial infarction (2.3%), resulting in a cardiac mortality of 2.3% in this group. The remaining 19 patients who did not have a DTST (9.1%) had coronary angiography based on evidence of significant cardiac disease resulting in one CABG and one percutaneous transluminal angioplasty. There was one (5.3%) perioperative myocardial infarction in this group and no cardiac deaths. Thirty-day mortality was 3.8%, perioperative MI rate was 3.8%, and perioperative cardiac mortality was 1.0%. During the follow-up period (median, 18 months; range, 1-89), there were 19 deaths (10%) and the 5-year cumulative survival was 76%. CONCLUSION: Selective use of DTST can direct further evaluation, intervention, and subsequent perioperative care. This algorithm has enabled us to perform AR even in patients with defined perfusion abnormalities with acceptable morbidity. The true sensitivity, specificity, and predictive value of DTST can only be determined by a prospective trial.

Adult↗
PubMed1996

Femoropopliteal bypass revisited: an analysis of 138 cases.

Femoropopliteal bypass is utilized for infrainguinal arterial reconstruction in patients with claudication, rest pain, non-healing ulcers and gangrene. Reported patency and limb salvage rates have varied considerably and controversy exists concerning conduit choice. The purpose of this study was to review the authors' results with femoropopliteal bypass to determine factors which may influence outcome in a contemporary series of patients. Between 1986 and 1991, 138 femoropopliteal bypasses were performed in 120 patients. Mean follow-up was 28 (range 1-66) months. Autogenous vein was used in 59% and polytetrafluoroethylene (PTFE) in the remainder. Above-knee anastomoses were performed in 34% and below-knee in 66%. The secondary patency for autogenous vein grafts (95% at 4 years) was significantly better than for PTFE grafts (69% at 4 years; P<0.01). Secondary patency for below-knee autogenous vein grafts also was better than that for below-knee PTFE grafts (95% versus 50% at 4 years; P<0.02). Limb salavage rates were worse for below-knee PTFE grafts than all other groups (P<0.01). Eight of 15 failed above-knee PTFE grafts were salvaged with below-knee autogenous vein grafts and did well. In the present series, autogenous vein femoropopliteal grafts demonstrated better overall patency and limb salvage. Below-knee PTFE bypasses should be reserved for limb salvage cases in patients without adequate autogenous conduits. Failed PTFE grafts can be salvaged by autogenous bypasses, yet an advantage to this approach was not seen.

Adult↗
PubMed1996

Effect of the duration of symptoms, transport time, and length of emergency room stay on morbidity and mortality in patients with ruptured abdominal aortic aneurysms.

BACKGROUND: Despite improvements in emergency medical services, surgical technology, and postoperative critical care, ruptured abdominal aortic aneurysm (AAA) is associated with constantly high morbidity and mortality. To determine the effect of the duration of symptoms, transport time to hospital, and length of emergency department assessment on outcome, we evaluated 124 consecutive patients with ruptured AAA treated during the past decade. METHODS: The medical records for 122 patients were abstracted for preoperative hypotension, cardiopulmonary resuscitation (CPR), blood loss, and three time intervals: symptom onset to operation, transport time to hospital, and emergency department assessment. RESULTS: Intraoperative mortality was 26% (n = 32), 30-day mortality was 51% (n = 63), and cumulative hospital mortality was 56% (n = 69). Death occurred in 52 (64%) of 81 patients with hypotension compared with 14 (35%) of 40 patients without hypotension (p < or = 0.01). Hypotension was present in 37 (82%) of 45 patients who arrived in the operating room in 2 hours or less compared with 26 (60%) of the 43 patients who arrived later than 2 hours (p < or = 0.05). Death followed in 21 (91%) of 23 patients who received CPR compared with 46 (46%) of 99 patients who did not receive CPR (p < or = 0.01). Bowel ischemia was observed in 18 (30%) of 60 patients who received more than 10 units of blood compared with 3 (5%) of 61 patients who received 10 units or less (p < or = 0.01). CONCLUSIONS: For patients with ruptured AAA, prolonged presurgical time was associated with a more hemodynamically stable patient and a lower mortality. Progressive bleeding in those hemodynamically stable patients was reflected by a larger blood transfusion requirement. Such patients exhibited an increased incidence of ischemic bowel complications, perhaps caused by splanchnic arterial ischemia augmented by preexisting atherosclerosis, as well as extrinsic compression by mesenteric hematomas.

Aged↗
PubMed1996

Ongoing vascular laboratory surveillance is essential to maximize long-term in situ saphenous vein bypass patency.

PURPOSE: The purpose of this study was to assess the contribution of ongoing graft surveillance to maximize long-term patency of lower limb in situ saphenous vein bypasses. METHODS: From January 1981 to October 1994, 556 autogenous grafts were constructed in 499 patients. The distal anastomosis was at the popliteal level in 207 (37%) and the tibial level in 349 (63%). All patients were enrolled in a prospective surveillance protocol to identify lesions that compromise graft patency and were evaluated at 1 day, 1 week, 6 weeks, and 3 months. Surveillance studies were then obtained every 3 months for the first 2 postoperative years and every 6 months thereafter. RESULTS: Four-hundred-fifty abnormalities were detected in 236 grafts. The median interval from the initial procedure to detection of an abnormality was 12 months (range 0 to 113 months) and varied with the location of the defect. Later in the life of the graft, progression of atherosclerotic disease manifested as inflow obstruction at a median of 15 months, and outflow disease threatened the graft at a median of 29 months (r = 0.0003). Of the 450 surveillance abnormalities, 294 (65%) occurred within the first 2 years after operation, and 156 (35%) developed more than 2 years after operation. Of the 236 grafts that developed surveillance abnormalities, 50 (21%) developed the initial defect more than 2 years after the initial bypass procedure. Eleven percent of grafts remaining free of abnormality after 2 years went on to fail. Sixty-seven interventions were performed on 62 extremities after 24 months, with 30 involving previously unrevised grafts. CONCLUSIONS: Because lesions amenable to revision continue to develop years after vein bypass construction, perpetual surveillance is required to ensure optimal rates of graft patency.

Analysis of Variance↗
PubMed1996

An outcome analysis of carotid endarterectomy: the incidence and natural history of recurrent stenosis.

PURPOSE: This report identifies the incidence of recurrent carotid stenosis after carotid endarterectomy (CEA) and records the natural history of the disease process to gain further insight into its proper management. METHODS: A prospective surveillance protocol with duplex imaging and velocity spectral analysis was used to detect recurrent stenosis ( > 50% diameter reduction) and to document the clinical outcomes of patients who underwent CEA. Between 1984 and 1993, 619 consecutive CEAs were performed in 587 patients. RESULTS: Recurrent carotid stenosis developed in 48 CEA sites (7.8%) during a mean follow-up interval of 34 months (range, 2 to 118 months). Normal results on intraoperative assessment correlated with a 5.6% incidence of recurrent stenosis, compared with a 19% incidence when a residual hemodynamic abnormality was present (p < 0.0003). In the first year after surgery, there were no transient ischemic attacks, strokes, or carotid occlusions from recurrent stenosis, compared with a 27% morbidity rate in later follow-up (p < 0.01). Three patients with recurrent stenosis subsequently had occlusion at the CEA site, two of whom had severe ipsilateral strokes. CONCLUSIONS: The incidence of recurrent carotid stenosis is low. Patients are at significant risk for neurologic morbidity when a recurrent stenosis occludes. With a 0.3% incidence of late stroke resulting from carotid bifurcation disease, these data confirm that CEA does provide long-term protection from stroke.

Aged↗
PubMed1995

Neurologic complications of reoperative and emergent abdominal aortic reconstruction.

Patients undergoing emergent and reoperative abdominal aortic reconstructions are at increased risk for ischemic neurologic complications. Between 1986 and 1992 five patients sustained ischemic injuries to the spinal cord, nerve roots, or lumbosacral plexus. Four patients underwent reoperative aortic procedures including removal of an infected aortobifemoral graft and extra-anatomic bypass (n = 3) and aortofemoral graft revision for primary graft failure (n = 1). A fifth patient had a ruptured common iliac aneurysm repaired with an aortobifemoral graft. Three patients undergoing reoperative aortic procedures developed lower extremity paraparesis, patchy sensory deficits, and bowel and bladder dysfunction. Physical examination and electromyography localized the injury to the level of the cauda equina or lumbosacral plexus. The other patient in this group developed incomplete T12 paraplegia. Surgical reconstruction resulted in internal iliac exclusion in all four patients. The incidence of neurologic deficits during this study period was 18% (3/17) in patients requiring aortofemoral graft excision for infection. The patient undergoing aneurysm repair was noted to have paraplegia after surgery and died on the fourth postoperative day. Autopsy revealed evidence of multiple emboli to the kidneys, bowel, and spinal cord. Neurologic deficits after reoperative and emergent abdominal aortic reconstructions are uncommon but devastating complications. Of particular concern is the incidence of neurologic deficits after removal of aortofemoral grafts with disruption of collateral flow to the spinal cord and nerve roots. Consideration should be given to maintaining retrograde perfusion of at least one internal iliac artery via common femoral artery reconstruction in these patients.

Aged↗