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Biomedical subjects

Richard M Green

Publications and source records attributed to Richard M Green.

16 recordsLinked to original sources
PubMed2003

Optimal operative strategies in repair of juxtarenal abdominal aortic aneurysms.

In an effort to identify preoperative and perioperative factors impacting outcome in repair of juxtarenal abdominal aortic aneurysm (JRAAA), hospital records and CT scans (for calcification, intraluminal thrombus, and aortic diameter) of all patients undergoing JRAAA repair over the past 10 years were reviewed. The 87 men and 25 women had a mean age of 72, and a mean maximal aortic diameter of 6.2 cm. Renal artery stenosis (RAS) and iliac disease were present in 13 (11%) and 40 patients (35%), respectively. Comorbidities included coronary artery disease (n = 49, 44%), COPD (n = 28, 25%), diabetes mellitus (n = 10, 9%), and preoperative renal insufficiency (PRI; Cr >1.4 mg/dL; n = 14, 12%). A midline incision was used in most of the patients (n = 98, 88%). The proximal aortic clamp was placed in the supraceliac (SC) position in 92 (82%) patients, and directly above one or both renal arteries in 20 (18%) patients. The overall mortality was 6% (n = 7). Cardiac complications occurred in 26 patients (23%); pulmonary, in 22 (20%); renal, in 14 (12%); and gastrointestinal, in 10 (9%). No patient experienced mesenteric ischemia. Mean elevation in creatinine was greater in patients with PRI (1.8 mg/dL vs. 0.13 mg/dL, p = 0.04). Mean blood loss (EBL) was 2701 +/- 189 cc, and mean LOS was 16.1 +/- 1.7 days. Age >70 was associated with increased length of stay (LOS) (12.1 days vs. 18.6 days, p = 0.05) and higher mortality (0 vs. 10%, p = 0.02); otherwise there were no significant relationships between pre- and perioperative parameters and any of the measured outcomes including death, postoperative RI, and LOS. Preferential SC clamping may substantially reduce complications of JRAAA repair (such as mesenteric and renal ischemia) related to proximal cuff disease, but cannot overcome the deleterious affects of advanced age and PRI.

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PubMed2003

Financial impact of endoscopic vein harvest for infrainguinal bypass.

PURPOSE: The purpose of this study was to determine the financial and clinical impact of endoscopic saphenous vein harvest for lower extremity bypass. METHODS: The charts of all patients who underwent elective infrainguinal bypass with saphenous vein since we began using endoscopic harvest were analyzed, and the data were compared with our concomitant series of conventionally harvested bypasses. Wound complications were classified as cellulitis (I), an open/draining wound (II), or threatened/exposed graft (III). Actual hospital costs were analyzed in a subset of 84 patients without excessive preoperative stay or additional major inflow or flap procedures, and the financial data were converted to 2001 US dollars. RESULTS: From March 1999 to December 2001, 242 bypasses were performed with open (n = 134) or endoscopic (n = 108) vein harvest techniques. Overall (34.1% versus 20.4%; P <.02) and class II (15.9% versus 6.5%; P <.03) wound complication rates and length of stay were significantly greater in the OPEN group. Financial subset analysis revealed a significant reduction in total cost ($6203 +/- $3326 versus $7456 +/- $3186; P <.01) in the ENDO versus the OPEN group. Readmissions for wound complications were more common in the OPEN versus the ENDO group (11.4% versus 4.1%; P <.03), resulting in an additional total cost of $204,557 versus $23,797, respectively. Patency and limb salvage at a mean of 7.1 months (range, 1 to 32 months) did not differ. CONCLUSION: Endoscopic saphenous vein harvest results in a cost savings of more than $1200 per procedure during hospitalization and of almost $2200 per procedure including the costs of readmission. This is primarily from a shortened length of stay, a decreased rate of major wound infections, and a reduction in the need for early readmission.

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PubMed2003

Is the rationale for carotid angioplasty and stenting in patients excluded from NASCET/ACAS or eligible for ARCHeR justified?

PURPOSE: To compare outcome after carotid endarterectomy (CEA) in patients who would have been excluded from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) or the Asymptomatic Carotid Atherosclerosis Study (ACAS) or would have been eligible for Acculink for Revascularization of Carotids in High Risk Patients (ARCHeR), a current high-risk stent registry, with outcome in a similar cohort at low risk. METHODS: Records of all CEAs performed at our institution from July 1993 to December 2000 were reviewed. Patients were assigned to groups either eligible or ineligible for NASCET and ACAS or ARCHeR, and criteria were stratified according to whether risk was defined by anatomic or medical problems or whether patients were ineligible according to nonmedical protocol exclusion criteria only. RESULTS: Preoperative and postoperative data were sufficient to determine risk status according to various study criteria in 857 patients. Stroke or death within 30 days, the primary end point, occurred in 2.1% of patients. Rates were similar in patients excluded from (2.7%) or included in (1.6%) NASCET and ACAS and in patients eligible (3.1%) or ineligible (2.1%) for ARCHeR. Rates did not differ according to whether exclusion or inclusion was based on anatomic risk, medical risk, or protocol exclusion, although trends favored worse outcome in the ARCHeR medical risk subgroup. A higher rate of minor complications was found in the elderly; however, stroke and death rates were similar according to age, gender, repeat procedure, or the presence of contralateral occlusion. CONCLUSIONS: No statistically or clinically significant differences were found in combined 30-day stroke or death rates after CEA in any group defined by previous surgical trials or current ongoing high-risk stent registry. While high-risk groups may exist, the premise that operative risk is higher in patients excluded from NASCET and ACAS or eligible for ARCHeR is not supported.

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PubMed2003

Internal carotid artery pseudoaneurysms: treatment with the Wallgraft endoprosthesis.

PURPOSE: To report several cases illustrating the feasibility and mid-term efficacy of deploying a self-expanding stent-graft to treat traumatic ruptures, pseudoaneurysms, and a spontaneous dissection of the internal carotid artery (ICA). CASE REPORTS: One patient suffered a stab wound and another developed a large pseudoaneurysm years after a gunshot to the neck. The third patient presented with a spontaneous rupture in the setting of fibromuscular dysplasia, and the final patient developed a pseudoaneurysm following carotid endarterectomy in an irradiated neck. All 4 patients were successfully treated with Wallgrafts deployed in the ICA using either an open carotid (first 3 cases) or percutaneous approach (fourth patient). There were no adverse neurological events. During a mean 16-month follow-up (range 6-24), duplex ultrasound and CT scanning found no evidence of restenosis, occlusion, or persistent perfusion of the pseudoaneurysm, which was noted to decrease in all cases. CONCLUSIONS: The thin-walled fabric of the Wallgraft appears capable of completely excluding the pseudoaneurysm, resulting in decreased aneurysm size over time.

Adult↗
PubMed2002

EEG changes during awake carotid endarterectomy.

To determine the reason for differing shunt rates based on electroencephalographic (EEG) and neurologic changes during general and regional anesthetic, respectively, we compared simultaneous EEG tracings and neurologic status in 135 patients undergoing carotid endarterectomy (CEA) under cervical block over a 30-month period. The decision to shunt in these patients was made on the basis of neurologic changes only irrespective of EEG findings. This group was then compared to the 288 patients undergoing CEA under general anesthetic with EEG monitoring over the same period. EEG changes occurred in 7.4% of awake patients and 15.3% of asleep patients (p < 0.03). The rates of ipsilateral hemispheric changes were similar, but no awake patient manifested global EEG changes with clamping while 3.5% of patients under general anesthesia did (p < 0.04). Global, but not hemispheric, changes were correlated with systolic blood pressure variability during clamping. This implies that global EEG changes in anesthetized patients may be the result of the anesthetic technique itself, and that cervical block may in fact be cerebroprotective.

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PubMed2002

Glucocorticoid-regulated VEGF expression in ischemic skeletal muscle.

Vascular endothelial growth factor (VEGF) is a potent neovascular inducer. Gene therapeutic delivery of a plasmid DNA encoding VEGF has been shown to impart collateral vessel development in animal models of hindlimb ischemia. Constitutive, long-lived expression of VEGF through gene transfer, however, may result in hypervascularization and/or leaky blood vessels. To that end, the introduction of regulated VEGF gene transfer technology may provide a safer and more controlled therapy for ischemic tissues. We developed a glucocorticoid-regulated plasmid vector (pNGVL-hAP/GRE(5)-vegf-pA) for modulating VEGF gene expression. This plasmid possessed five tandem repeats of the glucocorticoid-responsive element and adenovirus major-late promoter driving the expression of the VEGF(165) cDNA. Intramuscular delivery of this plasmid to mice, and subsequent treatment with the synthetic glucocorticoid dexamethasone (DEX), led to greatly enhanced VEGF expression. Similar delivery to the gracillis muscle of New Zealand white rabbits that had undergone ligation of their femoral artery to induce ischemia exhibited increased VEGF expression and collateral vessel development only in the presence of DEX. Additionally, reintroduction of DEX at a time point during which initial VEGF transgene levels had subsided resulted in a vigorous reinduction of VEGF transgene expression. This new iteration of VEGF gene delivery provides for fine-tuned angiogenic factor-based therapy for tissues requiring neovascularization.

Animals↗
PubMed2002

Transposed saphenous vein arteriovenous fistula revisited: new technology for an old idea.

Patients without renal function are living longer than in the past, and the provision of dialysis access is a growing problem. The distal end of the greater saphenous vein can be anastomosed to the femoral artery, creating a transposed saphenous vein thigh arteriovenous fistula, which offers the theoretical advantages of autologous conduit and a native venous 'anastomosis.' This is a rarely performed procedure, however, in part because of the morbidity of vein harvest and the risk of groin infection. We have been favorably impressed by the reduction in morbidity and wound infection following endoscopic vein harvest for lower extremity bypass, and believe that the success of this technique merits a reevaluation of this procedure.

Arteriovenous Shunt, Surgical↗
PubMed2002

Correlating carotid artery stenosis detected by panoramic radiography with clinically relevant carotid artery stenosis determined by duplex ultrasound.

OBJECTIVE: We sought to assess the utility of panoramic radiography as an adjunct screening tool for detecting significant asymptomatic carotid artery stenosis. The specific aim was to correlate calcifications seen in the region of the carotid bifurcation with clinically relevant carotid artery stenosis as determined by duplex ultrasound (DUS). STUDY DESIGN: Routine dental panoramic films of patients 55 and older (n = 778) at the University of Rochester Eastman Dental Center were retrospectively reviewed for calcifications around the carotid bifurcation. Patients with such calcifications were referred for DUS, and raw data were interpreted by a vascular surgeon blinded to the radiographic findings. Groups were compared by using the chi(2) test. RESULTS: Twenty-seven patients (3.5%) had suggestive radiographic calcifications on one or both sides, 20 of whom consented to DUS. Clinically significant carotid stenoses (>50% lumenal narrowing) were present in 50% of the sides with calcification compared with 21% of the sides without (P =.08, chi(2)). Three patients (15% of those screened with DUS) had stenoses greater than 80% and underwent 4 carotid endarterectomies as a direct result of screening. CONCLUSIONS: Data suggest that clinically significant stenosis may exist if calcifications are observed on panoramic radiographs. Incidental examination of this area carries a minimal cost and appears beneficial as a screening tool for carotid disease, although definitive testing must follow.

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PubMed2002

Hemodynamic benefits of regional anesthesia for carotid endarterectomy.

OBJECTIVE: The objective of this study was to define differences in perioperative hemodynamics and associated outcomes in patients who undergo carotid endarterectomy (CEA) with regional and general anesthesia. METHODS: All the patients who underwent CEA during a 25-month period were reviewed, with a comparison of those who underwent operation with cervical block anesthesia (CB) with those who underwent operation with general anesthetic (GA). Baseline intraoperative and postoperative blood pressure and heart rate were recorded, and deviation from initial values was calculated. The administration of vasoactive medications was assessed. Operative time, intensive care unit admission, postoperative length of stay, and cardiac/neurologic morbidity were recorded. RESULTS: From October 16, 1998, to December 1, 2000, 550 nonemergent CEAs were performed in 527 patients (226 with CB and 324 with GA). The patients in both groups were similar in age, presentation, and associated comorbidities. Although baseline blood pressure and heart rates were similar in both groups, those patients who underwent operation with GA had significantly greater intraoperative and postoperative hemodynamic variability and received more vasoactive medications during surgery (87% versus 51%; P <.001) and in the recovery room (36% versus 21%; P =.0009). Major postoperative blood pressure derangements were more common in the GA group (18% versus 10%; P <.05). Patients who underwent operation with GA more frequently needed intensive care unit admission (16% versus 7%; P =.01) and had more frequent delays in discharge (20% versus 11%; P =.008; postoperative length of stay, 2.1 versus 1.6 days; P =.01). Although no difference was seen in neurologic morbidity rates between groups (combined major stroke/death rate, 1.8%), the major cardiac morbidity rate was noted to be lower in the CB group (1% versus 4%; P =.05). The total in-room time was shorter in the CB group (108 versus 122 minutes; P <.001). CONCLUSION: CEA performed with CB is associated with significantly less perioperative hemodynamic instability than with GA. This results in fewer major adverse cardiac events. Ultimately, decreased critical care resource use is realized as is a shortened length of stay.

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PubMed2002

Free-tissue transfer in patients with peripheral vascular disease: a 10-year experience.

Advances in free-tissue transfer have allowed for lower limb salvage in patients with significant peripheral vascular disease and limb-threatening soft-tissue wounds. The authors retrospectively reviewed their 10-year experience with free flaps for limb salvage in patients with peripheral vascular disease to assess postoperative complication rates and long-term functional outcome. They identified all patients undergoing free-tissue transfer with significant peripheral vascular disease and otherwise unreconstructible soft-tissue defects. Charts were reviewed for perioperative and long-term outcome. Parameters studied included perioperative morbidity and mortality, flap success, bypass graft patency, ambulatory results, and long-term limb and patient survival. Survival data were analyzed using life-table analysis, Kaplan-Meier survival analysis, and Cox testing. A total of 79 flaps were examined in 75 patients with peripheral vascular disease from July of 1990 to November of 1999. All patients would have required a major amputation had free-tissue transfer not been performed. Mean age was 60 years, average hospital stay was 32 days, and perioperative mortality was 5 percent. Within the first 30 days after operation, there were four cases of primary flap loss, and another two were lost as the result of bypass graft failure (8 percent); five of these cases resulted in amputation. There were no primary flap failures after 30 days. Follow-up ranged to 91 months (mean, 24 months). During this time, another 14 limbs were lost, most commonly because of progressive gangrene and/or infection in sites remote from the still-viable free flap. Using Kaplan-Meier survival analysis, 5-year flap survival was 77 percent, limb salvage 63 percent, and patient survival 67 percent. Sixty-six percent of patients were able to ambulate independently with the use of their reconstructed limb at least 1 year after hospital discharge, although some of these later went on to amputation. Free-tissue transfer for lower extremity reconstruction can be performed with acceptable morbidity and mortality in patients with peripheral vascular disease. Flap loss is low, and limb salvage, ambulation, and long-term survival rates in these patients are excellent.

Follow-Up Studies↗
PubMed2002

Technical considerations for late removal of aortic endografts.

INTRODUCTION: The endovascular repair of abdominal aortic aneurysms has become increasingly common during the past decade. Despite aggressive attempts to treat endoleak and graft failure with endovascular salvage procedures, some grafts necessitate surgical removal. We reviewed our experience with late endograft explantation in an effort to identify technical maneuvers critical for success. METHODS: Of 110 patients treated with aortic abdominal endografts at the University of Rochester Medical Center between August 1997 and June 2001, five (4.5%) needed late graft removal. Medical records, radiographic files, and case report forms were retrospectively reviewed. RESULTS: One Talent (Medtronic AVE, Santa Rosa, Calif) and four Vanguard (Boston Scientific, Natick, Mass) grafts were removed at a mean of 32.7 months (range, 18 to 44 months) after implantation. One patient underwent conversion for rupture, three for endoleaks (one each with types I, II, and III), and one for stent separation from the graft material without endoleak or aneurysm expansion. Three cases were approached via the midline, one through a bilateral subcostal incision, and one through a retroperitoneal incision. Supraceliac aortic control was used in all patients. Removal of two of the Vanguard grafts necessitated extension of the aortotomy above the level of the renal orifices. One perioperative death occurred. The mean operative blood loss was 4700 mL (range, 1850 to 9000 mL), and length of stay was 19.8 days (range, 7 to 42 days). CONCLUSION: The morbidity and mortality rates associated with late removal of endografts are significant. Removal of Vanguard devices can necessitate extension of the aortotomy above the renal arteries. We believe that control of the aorta well above the proximal fixation site is the key to removal and that continuous aortic exposure via retroperitoneal exposure is the best option in this situation.

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