Hybrid treatment of aortic arch aneurysms.

The advent of thoracic aortic endovascular stent-grafting has drastically changed the management of thoracic aneurysms. In 1991, Volodos and colleagues performed the first hybrid aortic arch repair. The case involved an arch debranching with placement of an endograft in a patient with a previous repair for an aortic coarctation. Since that time, thoracic endografts have largely been incorporated into the treatment of aortic arch disease using hybrid approaches. In this article we will discuss the technical details of both the open and endovascular portion of hybrid aortic arch repairs. We will also review the evidence supporting the use of hybrid operations to repair aortic arch pathology, with a focus on mortality, morbidity and technical success.

Combined carotid endarterectomy and coronary bypass: a decade experience at UCLA.

PURPOSE: The purpose of this review was to determine outcomes for combined carotid endarterectomy (CEA) and coronary revascularization (CABG) in patients with asymptomatic carotid stenosis. METHODS: We reviewed the medical records of consecutive combined procedures (CEA and CABG), performed at UCLA Medical Center from October, 1989 to January, 1999. FINDINGS: There were 43 patients, 27 men and 16 women, with a mean age of 71 yr (range 51-87). Thirty-four patients 79% (34/43) had asymptomatic carotid stenosis. Stroke occurred in three patients (3/43 = 6.9%). Stroke ipsilateral to the CEA occurred in two patients: one asymptomatic (1/34 = 2.9%) and one symptomatic (1/9 = 11.1%). CONCLUSIONS: The majority of patients undergoing combined CEA/CABG have asymptomatic carotid stenosis identified in preparation for elective CABG. The asymptomatic carotid subset stroke rate of 2.9% resulting from a combined CEA/CABG is higher than our reported rate for CEA performed alone. In patients with asymptomatic carotid stenosis, the combined procedure should be selectively performed.

Carotid endarterectomy with normal findings from a completion study: Is there need for early duplex scan?

OBJECTIVE: The objective of this study was to determine the value of early (< 6 months) duplex scanning after carotid endarterectomy (CEA) with an intraoperative completion study with normal results. Attention was paid to restenosis rates and reoperation for recurrent stenosis within the first 6 months. METHODS: A retrospective review was performed on 380 CEAs (338 patients) with intraoperative completion studies and duplex surveillance within the first 6 months. Results of completion studies, restenosis rates, and recurrent symptoms were evaluated for each operation. Studies were performed from 0 to 200 days postoperatively (median, 28). RESULTS: Intraoperative completion studies included 333 angiograms, 26 duplex scans, and 21 angiograms with duplex scans. Of the 380 intraoperative completion studies, 28 (7.5%) had abnormal findings, including 14 abnormal internal carotid arteries (ICAs). Twenty-four procedures were revised, and the findings of all repeat completion studies were normal. Of the initial completion studies, in four cases, abnormalities (3 ICAs) were insignificant and did not warrant further intervention. Follow-up ICA duplex scans had normal results after 364 (95.8%) CEAs. There were 14 mild recurrent ICA stenoses and two moderate recurrent ICA stenoses; neither had abnormal findings from the completion study. There were no severe recurrent ICA stenoses. External carotid artery (ECA) recurrent stenosis included 7 mild, 15 moderate, and 9 severe restenoses. CONCLUSIONS: Only 0.5% of CEAs developed moderate restenosis. No procedures had severe recurrent stenosis on duplex scan within the first 6 months, and none required intervention. Duplex surveillance in the first 6 months is relatively unproductive, providing that there were normal results from an intraoperative completion study for each patient. Routine surveillance can be started at 1 year.

Surgical aspects of dialysis in newborns and infants weighing less than ten kilograms.

PURPOSE: Renal failure occurs in children with moderate frequency. Surgical aspects of establishing and maintaining dialysis access in small infants are exceptionally challenging. The purpose of this review is to evaluate the authors' experience with dialysis access for infants less than 10 kg, particularly with respect to the surgical care required. METHODS: A retrospective review was conducted between 1991 and 1999 of all pediatric dialysis patients weighing 10 kg or less (n = 29). Age at start of dialysis, duration of dialysis, modes of dialysis, and complications specific to peritoneal (PD) and hemodialysis (HD) were examined. RESULTS: The mean age at start of dialysis was 10.4 months and continued for an average duration of 16.3 months. Seventy-two percent of all patients required both modes of dialysis. HD and PD duration averaged 7.8 and 10.5 months, respectively. Catheter durability was 3.1 and 4.5 months per catheter for HD and PD, respectively. There was no significant difference in complications when comparing HD and PD. Patients who weighed 5 to 10 kg had significantly longer PD catheter durability than patients 0 to 5 kg (P = .001). Forty-one percent of patients terminated dialysis after transplantation, whereas 24% died awaiting transplantation. CONCLUSION: Despite a large number of operations required, infants less than 10 kg can be bridged successfully, by surgical intervention and subsequent dialysis, to transplantation.

Combined revascularization and microvascular free tissue transfer for limb salvage: a six-year experience.

Atherosclerotic vascular disease causing extensive tissue loss of the lower extremities often results in primary amputation. Combined revascularization and free tissue transfer has been described as a method of extending limb salvage to these patients. The durability of this combined procedure remains unknown, thus the objective of this report is to describe the immediate and long-term results in a series collected over 6 years. From 1992 to 1998, 15 patients with a mean age of 60 years underwent combined revascularization and free tissue transfer. Mean ulcer size measured 45 cm(2) for a mean duration of 7.4 months preoperatively and 12 patients had exposed bone or tendon. Vascular reconstruction included popliteal (3), tibial (6), and pedal (6) bypass with concomitant myocutaneous free flap, using mostly rectus abdominis or latissimus dorsi muscle. There were no perioperative deaths. One patient suffered a nonfatal myocardial infarction. Two patients had a postoperative wound hematoma and one required vascular graft revision. Patients were followed for 4 to 75 months (mean = 23 months). Four patients have required amputations (3 early, 1 late), three of whom had preoperative renal failure. The limb salvage rate has been 72% at 36 months,

The effects of thrombus, thrombectomy and thrombolysis on endothelial function.

OBJECTIVE: this study was undertaken to examine and compare the effects of thrombus, thrombectomy, and thrombolysis on endothelial function as measured by endothelium-dependent vasorelaxation (EDR). METHODS: adult, male New Zealand white rabbits underwent ligation of the left common iliac to femoral artery to induce thrombosis and were then randomly assigned to one of five groups, n=6 in each. Group A consisted of ligation and thrombosis for 4 h. Group B underwent similar ligation for 4 h, but without intraluminal thrombus present. Following 4 h of ligation and thrombosis, Group C underwent thrombectomy while group D was treated with urokinase (UK), 4000 U/min for 30 min. Group E underwent UK infusion alone. The right external iliac artery served as control vessel in each group. All arteries were removed and endothelial function was determined by measuring EDR. RESULTS: the presence of thrombus reduced EDR by 50% (group A) compared to control. Vessels with interrupted flow, but not exposed to thrombus, retained normal EDR (group B). Thrombectomy decreased EDR significantly (group C) compared to thrombolysis (group D) and control. UK did not significantly alter EDR (groups D, E). CONCLUSIONS: exposure of endothelium to thrombus significantly decreases EDR. EDR was not affected by interruption of blood flow in the absence of thrombus. Thrombectomy appeared to cause a further additive insult to the endothelium. In contrast, thrombolysis with UK preserved residual endothelial function. These data suggest that it is important to differentiate the effects of thrombus on endothelium from effects due to thrombectomy or thrombolysis when evaluating treatment modalities for arterial thrombosis.

Pseudo-occlusion and/or pseudo-stenosis of the intracranial internal carotid artery.

This report summarizes our recent experience with two patients who presented with symptoms ipsilateral to a severe carotid stenosis at the bifurcation, with one having a severe stenosis at the siphon and the other an occlusion of the internal carotid artery in its intracranial portion. These lesions were documented on preoperative angiography. In both instances, persistence of symptoms, despite maximal medical therapy, led us to proceed with carotid endarterectomy. In both cases, intraoperative angiography confirmed a normal intracranial internal carotid artery, contrary to what had been seen on preoperative angiography. Carotid endarterectomy was performed, with resolution of clinical symptoms in both cases. This experience suggests that the appearance of the intracranial portion of the carotid artery can be significantly affected by the presence of a proximal lesion at the bifurcation. Stenosis and/or occlusion of the intracranial portion of the carotid artery may appear on preoperative angiography secondary to flow alterations as a result of the more proximal lesion. This, in part, may explain why many patients with combined extracranial and intracranial arterial disease improve after carotid endarterectomy and suggests that, in the presence of a severe extracranial lesion, further evaluation be undertaken to exclude the possibility of pseudo-stenosis or pseudo-occlusion of the intracranial carotid artery.

Endovascular repair of abdominal aortic aneurysm using the EVT device: limited increased utilization with availability of a bifurcated graft.

PURPOSE: To determine if the availability of a bifurcated graft would increase the percentage of patients eligible for endovascular repair of abdominal aortic aneurysms (AAAs). METHODS: One hundred eighty-five consecutive patients were evaluated prospectively for endovascular AAA repair at a university referral center. Data were collected on eligibility for tube or bifurcated endovascular grafts, reasons for exclusion, aneurysm morphology, and the interventions performed. RESULTS: Forty-six (25%) patients were eligible for endovascular treatment using the first-generation Endovascular Technologies (EVT) system: 19 (10%) for a tube graft and 27 (15%) for a bifurcated device. An unsuitable proximal neck was the reason for exclusion in 48% of patients (excess diameter in 27%, inadequate length in 21%). Unsuitable iliac configuration was present in 41% of those excluded; 29% of the common iliac arteries were enlarged or aneurysmal, while 12% were small or tortuous. CONCLUSIONS: Although a bifurcated graft more than doubles the eligibility of AAA patients for endovascular repair, the configuration of the proximal neck and iliac disease excluded the majority of AAA patients from endovascular therapy using the first generation EVT device.

Repair of type IV thoracoabdominal aneurysm with a combined endovascular and surgical approach.

We report an unusual case of type IV Thoracoabdominal Aneurysm (TAA) with Superior Mesenteric Artery (SMA), celiac artery, and bilateral renal artery aneurysms in a patient who underwent an earlier repair of two infrarenal Abdominal Aortic Aneurysm (AAA) ruptures. Because of the presence of the visceral artery aneurysms and the earlier operation through the retroperitoneum, standard surgical treatment via a retroperitoneal approach with an inclusion grafting technique was considered difficult. A combined surgical approach achieving retrograde perfusion of all four visceral vessels and endovascular grafting allowing exclusion of the TAA was accomplished. Complete exclusion of the aneurysm and normal perfusion of the patient's viscera was documented by means of follow-up examinations at 3 and 6 months. The repair of a type IV TAA with a Combined Endovascular and Surgical Approach (CESA) allowed us to manage both the aortic and visceral aneurysms without thoracotomy or re-do retroperitoneal exposure and minimized visceral ischemia time. If the durability of this approach is confirmed, it may represent an attractive alternative in patients with aneurysmal involvement of the visceral segment of the aorta.

Abdominal aortic aneurysm: a 6-year comparison of endovascular versus transabdominal repair.

OBJECTIVE: To test the hypothesis that endovascular repair of abdominal aortic aneurysm (AAA) will result in a significant reduction in mortality and morbidity rates and cost when compared with open transabdominal repair. SUMMARY BACKGROUND DATA: Since the introduction of endovascular repair of AAA this decade, multiple groups have evaluated different endovascular grafts. Despite the excellent results reported initially, there has been a paucity of well-controlled, comparative studies looking at long-term outcome. METHODS: From 1992 to 1998, the first 100 consecutive patients undergoing endovascular AAA repair (mean age 74.7, AAA size 5.6 cm) were compared to 100 patients undergoing transabdominal repair (mean age 72.9, AAA size 5.9 cm). All patients undergoing endovascular repair received a device manufactured by Endovascular Technologies, Inc. (Menlo Park, CA) and were prospectively followed with periodic examination, contrast-enhanced computed tomography, and duplex scanning. Of the 200 patients, 198 have been available for long-term follow-up. RESULTS: The two groups had similar preoperative risk factors. Surgical time (211 vs. 256 minutes, p < 0.005), blood loss (326 vs. 1010 ml, p < 0.005), and blood replacement (0.4 vs. 1.6 units, p < 0.005) were all decreased in the endovascular group. Median intensive care unit stay (0 vs. 2 days) and hospital stay (2 vs. 7 days) were significantly reduced in the endovascular group. Insignificant trends in lower morbidity rates (myocardial infarction 1 % vs. 5%, respiratory failure 1 % vs. 5%, colon ischemia 0% vs. 2%) were present in patients undergoing endovascular repair. This led to decreased hospital cost and increased hospital profit. The surgical mortality rate (2% vs. 3%) and 5-year survival rate (65% vs. 72%) have been equivalent between the two groups. CONCLUSIONS: The surgical mortality rate is low for both groups and not statistically different. Endovascular repair significantly reduces resource utilization (surgical time, blood replacement, intensive care unit and hospital stay) and cost when compared to transabdominal aneurysm repair. Long-term survival is equivalent in patients undergoing AAA repair regardless of technique. Although endovascular repair appears durable for up to 6 years, longer follow-up studies are warranted.

Achieving cost-effective endoluminal aneurysm repair.

Endovascular repair of abdominal aortic aneurysms has emerged as a viable alternative to open surgical repair. This procedure will be demanded by physicians and patients because of its lower morbidity and faster recovery. However, its eventual role in the management of patients with abdominal aortic aneurysm is likely to be further defined by cost concerns. Currently, endovascular abdominal aortic aneurysm repair is a moving target and thus requires continued analysis of its fiscal impact. Given that it is likely to be a clinically preferable approach, it is important that we explore ways to make it financially viable. Available information on cost of endovascular aneurysm repair is limited; however, cost saving strategies can be developed that will help establish this alternative in the armamentarium of specialists treating patients with abdominal aortic aneurysms.

Endovascular, transperitoneal, and retroperitoneal abdominal aortic aneurysm repair: results and costs.

PURPOSE: Contemporary treatment of abdominal aortic aneurysms (AAA) includes transabdominal (TA), retroperitoneal (RP), and endovascular (EV) repair. This study compares the cost and early (30-day) results of a consecutive series of AAA repair by means of these three methods in a single institution. METHODS: A total of 125 consecutive AAA repairs between February 1993 and August 1997 were reviewed. Risk factors, 30-day morbidity and mortality rates, and hospital stay and cost were analyzed according to method of repair (TA, RP, EV). Cost was normalized by means of a conversion factor to maintain confidentiality. Cost analysis includes conversion to TA repair (intent to treat) in the EV group. RESULTS: One hundred twenty-five AAA repairs were performed with the TA (n = 40), RP (n = 24), or EV (n = 61) approach. Risk factors among the groups (age, coronary artery disease, hypertension, diabetes, chronic obstructive pulmonary disease, and cigarette smoking) were not statistically different, and thus the groups were comparable. The average estimated blood loss was significantly lower for EV (300 mL) than for RP (700 mL) and TA (786 mL; P>.05). Statistically significant higher cost for TA and RP for pharmacy and clinical laboratories (likely related to increased length of stay [LOS]) and significantly higher cost for EV in supplies and radiology (significantly reducing cost savings in LOS) were revealed by means of an itemized cost analysis. Operating room cost was similar for EV, TA, and RP. There were six perigraft leaks (9.6%) and six conversions to TA (9.6%) in the EV group. CONCLUSION: There were no statistically significant differences in mortality rates among TA, RP, and EV. Respiratory failure was significantly more common after TA repair, compared with RP or EV, whereas wound complications were more common after RP. Overall cost was significantly higher for TA repair, with no significant difference in cost between EV and RP. EV repair significantly shortened hospital stay and intensive care unit (ICU) use and had a lower morbidity rate. Cost savings in LOS were significantly reduced in the EV group by the increased cost of supplies and radiology, accounting for a similar cost between EV and RP. Considering the increased resource use preoperatively and during follow-up for EV patients, the difference in cost between TA and EV may be insignificant. EV repair is unlikely to save money for the health care system; its use is likely to be driven by patient and physician preference, in view of a significant decrease in the morbidity rate and length of hospital stay.

Leiomyosarcoma of the inferior vena cava: prognosis and comparison with leiomyosarcoma of other anatomic sites.

BACKGROUND: Leiomyosarcoma of the inferior vena cava (IVC) is an uncommon tumor that many believe portends a poor prognosis compared with leiomyosarcoma with similar histology at other anatomic sites. Because of the limited international experience with this disease, the optimal management of these patients is unknown. METHODS: From October 1978 to January 1997, 14 patients with leiomyosarcoma of the IVC were treated at the University of California-Los Angeles Medical Center. Wide resection was attempted in all patients. The characteristics of each patient were documented and compared with those of patients with leiomyosarcoma of the stomach (n = 13), small intestine (n = 18), retroperitoneum (n = 19), and uterus (n = 10) who were treated during the same time period. RESULTS: Age, gender, tumor size, tumor grade, and lymph node status did not impact survival of patients with leiomyosarcoma of the IVC. Patients with positive surgical margins fared significantly worse (P < 0.03) compared with those who underwent complete resection. Radiation therapy diminished local recurrence and may improve median survival (6 months [n = 2] vs. 51 months [n = 12]) in this patient population. Patients who received combined chemotherapy and radiation lived longer than those who did not (P < 0.05). The 5-year cumulative survival rate (Kaplan-Meier method) was 53% for patients with leiomyosarcoma of the IVC, 47% for those with leiomyosarcoma of the stomach, 43% for those with leiomyosarcoma of the small intestine, 56% for those with leiomyosarcoma of the retroperitoneum, and 65% for those with leiomyosarcoma of the uterus. CONCLUSIONS: Despite having a tumor that originates from the IVC, patients with this tumor type can enjoy reasonably long term survival. It appears that these patients benefit from radiation therapy to control local disease. Survival of these patients is no worse than of patients with leiomyosarcomatous lesions of other origin. Aggressive surgical management combined with adjuvant therapy offers the best treatment for patients with leiomyosarcoma of the IVC.

Abdominal aortic aneurysm repair in patients with renal allografts.

Aortic reconstruction is being reported in an increasing number of patients after renal transplantation as a result of improved renal graft survival and life expectancy. Aortic surgery in these patients places the pelvic allograft at risk for ischemic damage. We present two separate modalities that have been successfully used in protecting the renal transplant from prolonged warm ischemia during abdominal aortic aneurysm (AAA) repair in two cases. One technique involves an aortofemoral shunt using the perirenal aorta for proximal cannulation and the other technique utilizes an indwelling shunt through the prosthetic graft. Both patients had an uneventful recovery with no evidence of renal dysfunction and their renal function has been stable on long-term follow-up. These cases illustrate two useful alternatives in providing pulsatile perfusion to a transplanted kidney in the iliac fossa during AAA repair. They have been used successfully as simpler alternatives to temporary axillofemoral bypass or extracorporeal pump oxygenation in preventing postoperative renal dysfunction.

Carotid artery repair for radiation-associated atherosclerosis is a safe and durable procedure.

OBJECTIVE: The development of carotid atherosclerosis after neck irradiation is well documented. There has been concern about the safety and durability of carotid artery repair through a radiated field. The objective of this report is to describe the immediate and long-term results of a series of cases collected in a 13-year interval. METHODS: From 1984 to 1997, 24 patients underwent 26 carotid artery operations. All the patients had undergone prior radiation therapy at a mean interval of 17 years, with an average radiation dose of 6300 rad. Severe scarring of the skin or radiation fibrosis were present in two thirds of the patients, with 4 patients having permanent tracheostomies. The indications for carotid surgery included cerebral or monocular transient ischemic attack (58%), asymptomatic high-grade stenosis (27%), prior stroke (12%), and tumor invasion of the carotid artery (4%). General anesthesia was used with selective shunting on the basis of carotid artery back pressure or electroencephalography monitoring. Patch angioplasty closure was used in 79% of the patients. The operations included standard carotid endarterectomy (n = 20), external carotid endarterectomy (n = 2), carotid patch angioplasty alone (n = 2), aortocarotid bypass grafting (n = 1), and carotid interposition grafting (n = 1). Four patients required skin grafting or myocutaneous flaps. RESULTS: No deaths or strokes occurred within 30 days of the operations. Six patients had transient cranial nerve palsy, and two had wound infections. The patients were followed from 1 to 156 months, with six patients being followed for longer than 18 months. No strokes were seen at late follow-up examination. Duplex scan examination documented one occlusion, in a patient with primary closure, and two restenoses, one of which necessitated reoperation. The remainder of the grafts were widely patent. CONCLUSIONS: Carotid surgery after neck irradiation is safe and durable. The long-term patency rates and the protection against subsequent neurologic events are similar to the results obtained in the absence of radiation therapy. Problems of wound healing were not found in this series.

Prosthetic replacement of the inferior vena cava for malignancy.

PURPOSE: Invasion of the inferior vena cava (IVC) by tumor is generally considered a criterion of unresectability. This study was designed to review the outcomes of a strategy of aggressive resection of the vena cava to achieve complete tumor resection coupled with prosthetic graft placement to re-establish caval flow. METHODS: Retrospective review of patients treated at a university referral center. Ten patients (mean age 54; eight females, two males) underwent tumor resection that involved circumferential resection of the IVC and immediate prosthetic replacement with ringed polytetrafluoroethylene (PTFE) grafts ranging in diameter from 12 to 16 mm. RESULTS: Seven patients had replacement of the infrarenal IVC, two of their suprarenal IVC, and one had reconstruction of the IVC bifurcation. Four of the 10 patients received preoperative chemotherapy, and none received radiotherapy. The most common (7/10) pathologic diagnosis was leiomyosarcoma arising from the IVC or retroperitoneum. Additional diagnoses included teratoma (one), renal cell carcinoma (one), and adrenal lymphoma (one). There were no perioperative deaths, and one complication (prolonged ileus) occurred. Mean length of stay was 8.1 days. Anticoagulation was not routinely used intraoperatively or postoperatively. Follow-up (mean duration = 19 months) demonstrated that survival was 80% (8/10) and 88% (7/8) of patients were free of venous obstructive symptoms. CONCLUSION: Resection of the IVC with prosthetic reconstruction allows for complete tumor resection and provides durable relief from symptoms of venous obstruction.

Dexamethasone and enalapril suppress intimal hyperplasia individually but have no synergistic effect.

Vascular injury is associated with complex interactions that lead to development of intimal hyperplasia (IH). We have demonstrated previously that the corticosteroid dexamethasone and the ACE-inhibitor enalapril are effective in suppressing the development of IH. We hypothesize that due to distinctly different pharmacologic mechanisms of action, a synergistic effect would be expected if these agents were given in combination. Forty New Zealand White rabbits underwent balloon catheter denudation of the carotid artery. Animals were divided into four equal treatment groups and received daily intramuscular injections: Group 1, saline; Group 2, enalapril 0.07 mg/kg, Group 3, dexamethasone 0.125 mg/kg; and Group 4, enalapril 0.07 mg/kg plus dexamethasone 0.125 mg/kg. Vessels were harvested at 12 weeks and intimal hyperplasia was measured as a ratio of the absolute area of IH to the normalized area enclosed by the internal elastic lamina (IH/IEL). Mean values for IH/IEL are expressed as a percent (SD): Group 1, 32.31 (14.9); Group 2, 9.47 (2.11); Group 3, 5.40 (4.14); and Group 4, 8.49 (4.27). All treatment groups demonstrated significant suppression of IH compared to the control group (p < 0.01); dexamethasone was more effective than enalapril (p = 0.01). There was no statistical difference in IH suppression between respective agents and the combination group (p > 0.10). Coadministration of dexamethasone and enalapril provides no advantage over single-agent therapy in suppressing the development of IH, suggesting that maximal suppression is obtained with single-agent treatment or that these agents affect IH through a common pathway.

Cigarette smoking increases endothelial-derived vasorelaxation in the rat carotid artery in a dose-dependent manner.

While there is clear-cut epidemiologic, morphologic, and functional evidence to suggest that cigarette smoking is deleterious to the cardiovascular system and endothelium, previous experiments with regard to the effect of cigarette smoking on endothelial-derived vasorelaxation are not conclusive. This study examines the effect of cigarette smoking on endothelium-derived vasorelaxation and its relationship to serum nitric oxide concentrations. Fourteen Sprague-Dawley rats (350-500 g) were divided into two groups (N = 7). The experimental group was exposed to six cigarettes (Kentucky 1R4F) per day for 50 days using a Griffith snout exposure method. The two groups were sacrificed and the carotid arteries were mounted on isometric force transducers in a physiologic bath. The arteries were constricted with norepinephrine (1 x 10(-4) M). Vasorelaxation to acetylcholine (Ach) was measured in a dose response manner. Vasorelaxation to nitroglycerin was measured at 10(-4) M. After the rats were sacrificed, blood samples from each rat were examined for total nitrate/nitrite concentration with serum chemiluminescence on a vanadium column. The results were analyzed with ANOVA and the Student's t test. Vasorelaxation to nitroglycerin was 17.42% +/- 0. 44 versus 16.25% +/- 0.42 in the control and smoke exposure groups, respectively (P = 0.19). This experiment counterintuitively demonstrates that cigarette smoking augments endothelial-derived vasorelaxation. No effect was noted in the endothelium-independent vasorelaxation to nitroglycerin. Alternative mechanisms including the presence of hypoxia and exogenous nitric oxide, which lead to endothelial-dependent and -independent vasorelaxation secondary to cigarette smoking, may serve to explain the apparent augmentation of endothelial-derived vasorelaxation. Further experiments with isolated components of smoke will need to be done to resolve the debate.