Nostrums, quackery, and ethics in vascular surgery: How to remain true to the path of Hippocrates and still feed our families.
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Certification↗
Biomedical subjects
Enrico Ascher
Publications and source records attributed to Enrico Ascher.
The Dialysis Outcome and Quality Initiative (DOQI) recommendations.
National surveys have demonstrated that the US End Stage Renal Disease (ESRD) program has witnessed an increasing number of patients each and every year with a corresponding increase in cost. However, when compared to the data from the ESRD program of other countries, we find that these US patients have a low rate of autogenous arteriovenous access (AVA) placement and increased use of nonautogenous (or prosthetic) AVA. Some of the impetus for this can be attributed to (1) the lack of adequate or easily identifiable superficial veins in patients starting on hemodialysis with a history of multiple venipuncture or obesity, (2) earlier access rates of nonautogenous AVA as compared to autogenous AVA, (3) the relative ease of placement of nonautogenous AVA, and (4) a prior payment differential in favor of nonautogenous AVA placement that has since been abolished. However, by virtue of the increased number of procedures required to maintain nonautogenous AVA patency when compared to that of autogenous AVA patency, hemodialysis access failure has become the most frequent cause of hospitalization among ESRD patients. To further investigate this issue, the National Kidney Foundation Dialysis Outcome and Quality Initiative (DOQI) organized multidisciplinary work groups who reviewed 3325 articles concerning various issues of ESRD over a 2-year period. They suggested that autogenous AVA have the best longer-term patency rates and require the fewest interventions as compared to other access types. In order to improve overall patency rates and help contain angioaccess costs, these DOQI recommendations were published in 1997 and updated in 2000. While there is evidence that the guidelines are slowly being adopted, there remains much room for improvement in their implementation.
Arteriovenous Shunt, Surgical↗
Differential expression of YAMA/CPP-32 by T lymphocytes in popliteal artery aneurysm.
BACKGROUND: We have previously demonstrated that programmed cell death, proteolytic activity, and inflammatory infiltrate in the aneurysmal wall may have a role in the pathogenesis of popliteal artery aneurysms (PAA). This investigation examines the expression of a cell death-promoting molecule, a cysteine protease, YAMA/CPP-32 in a series of PAA specimens. METHODS: Twenty PAA specimens were obtained from patients undergoing elective surgical repair. Normal controls were popliteal arteries obtained from patients without PAA who were undergoing infrainguinal bypass surgery (n = 8). Standard histochemistry techniques were used to assess inflammatory infiltrates in PAA. Expression of apoptosis-promoting molecule, CPP-32, vascular smooth muscle cells (VSMC), macrophages, and T lymphocytes was detected by immunohistochemistry. RESULTS: There is a conspicuous disruption and fragmentation of elastic lamellae and increased inflammatory infiltrate in the PAA as compared with normal arteries. As compared with normal popliteal artery tissues, the PAA demonstrated large number of cells immunopositive for CPP-32 (60.45 +/- 4.25% P < 0.05). This study revealed significantly increased expression of CPP-32 in the T-cell population of the PAA as compared with the other cells (P < 0.01). Dual immunolabeling and investigation of serial sections demonstrated that co-expression of CPP-32 was maximum in the CD8+ subset (37 +/- 3.3% of the total CPP-32 immunoreactive cells identified). CONCLUSIONS: The data emphasize that the inflammatory infiltrate in the PAA walls has a significant role in the pathogenesis of this vascular disorder. Cells expressing death-promoting molecules are present in large numbers and are predominantly T lymphocytes in PAA. In addition to compromising the mechanical integrity of the vessel wall, apoptosis in the inflammatory infiltrate may contribute to the production of cytokines, activation of other signaling molecules such as stress proteins that could eventually favor PAA development.
Aged↗
Revisiting the appropriateness of carotid endarterectomy.
BACKGROUND AND PURPOSE: In the 1980s, carotid endarterectomy was controversial because proof of efficacy was lacking, complication rates were high, and one third of cases were reported to be inappropriate. Since publication of several randomized controlled trials (RCTs), rates of carotid endarterectomy have doubled nationwide. This study assesses the appropriateness and use of carotid endarterectomy since publication of the RCTs. METHODS: Using the literature, we developed a list of 1557 mutually exclusive indications for carotid endarterectomy and asked a panel of national experts to rate the appropriateness of each indication using the RAND methodology. We used these ratings to assess appropriateness in a sample of 2124 patients who underwent the procedure in 1997 to 1998 in 6 hospitals. We also analyzed the reasons for the procedure and rates of death, stroke, and myocardial infarction within 30 days of surgery. RESULTS: Overall, 84.9% of operations were done for appropriate reasons, 4.5% for uncertain reasons, and 10.6% for inappropriate reasons. Among procedures considered inappropriate, the most common reasons were high comorbidity (46.6%) and minimal stenosis (27.1%). Overall, 72.5% were asymptomatic, 17.4% had a carotid transient ischemic attack, and 10.1% had a stroke. The 30-day rate of death or stroke was 5.47% for symptomatic patients and 2.26% for asymptomatic patients. Among patients having combined carotid and coronary artery bypass graft surgery, the rate was 10.32%. The complication rate in asymptomatic patients with high comorbidity was 5.56%. CONCLUSIONS: Since the RCTs, rates of overuse appear to have fallen considerably, although they are still significant. A major shift has occurred toward operating on asymptomatic patients. Although overall complication rates were low, rates among asymptomatic patients with high comorbidity exceeded recommended thresholds.
Aged↗
Acute lower limb ischemia: the value of duplex ultrasound arterial mapping (DUAM) as the sole preoperative imaging technique.
Contrast arteriography (CA) is the gold standard preoperative imaging modality for patients with chronic and acute lower limb ischemia. We have previously shown that high-quality DUAM can safely replace CA in patients with chronic ischemia. The goal of this study was to investigate whether DUAM can also be used effectively in the setting of acute ischemia. From January 1998 to February 2001, 68 patients were admitted to our institution with 87 instances of acute lower limb(s) ischemia and underwent 87 operations. There were 34 men and 34 women whose age ranged from 51 to 95 years (mean 72 +/- 12.5). There were 44 cases of acute arterial occlusions and 43 cases of bypass graft thromboses. In the former group the most proximal occluded site based upon duplex was the aorta in 1 case, common iliac in 4 cases, external iliac in 15 cases, and infrainguinal arteries in 24 cases. In the latter group, there were 4 suprainguinal grafts, 24 bypasses to the popliteal artery, and 15 bypasses to infrapopliteal arteries. All patients had DUAM as their initial diagnostic study. The duplex protocol varied according to the pulse exam. In patients with a good femoral pulse but absent popliteal pulse, attempts were made to visualize the ipsilateral femoral-popliteal segment and the proximal third of the infrapopliteal arteries. This was extended to the pedal arteries in cases of proximal occlusion. When the femoral pulse was absent the protocol included visualization of the distal aorta, bilateral iliac, and common femoral arteries. This exam was extended into the deep and superficial femoral-popliteal segments in cases of proximal occlusion. None of these cases had preoperative or prebypass CA. Intraoperative arterial pressures to confirm the adequacy of the inflow tract and completion arteriography to assess the runoff were performed in 78% of the cases at the end of the procedure. This initial experience suggests that high-quality DUAM may replace CA in patients with lower limb ischemia. DUAM provides a reliable assessment of the inflow and outflow arteries even in very low-flow situations. In addition, DUAM can identify the cause of the arterial occlusion, thereby making therapy more effective and less time consuming.
Acute Disease↗
Preliminary results of the new 6F TrapEase inferior vena cava filter.
The TrapEase filter is a permanent, symmetric nitinol filter that can be deployed through a low-profile sheath. Although the TrapEase is enjoying an increasing market share of inferior vena cava (IVC) filters, there are still limited clinical follow-up data on its use. This study is a retrospective review of 189 consecutive infrarenal TrapEase filters placed at our institution. The study included 80 men and 109 women, with an average age of 73 years (24-102). The most common indication for filter placement was a contraindication to warfarin. In total, 13% of the patients were treated with warfarin. The filter was successfully deployed in all cases, via the right femoral vein in 57% of the patients, via the left femoral vein in 32%, and via the right internal jugular vein in 11%. Follow-up studies were performed as clinically indicated. During the investigation, there were three cases of IVC thrombosis (1.5%) and one case of retroperitoneal hemorrhage potentially caused by filter placement. Two of the thrombosis cases resulted in serious sequelae. This study also represents the first report of a symptomatic pulmonary embolism (PE) after TrapEase filter placement. While this investigation does demonstrate a low overall complication rate of this new device, it raises the concern of an increase in IVC thrombosis rate.
Adult↗
Presidential address: The modern vascular specialist--surgeon, clinician, and interventionist.
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Education, Medical, Graduate↗
Endovascular management of axillofemoral bypass graft stump syndrome.
OBJECTIVE: Upper extremity embolic complications of occluded axillofemoral bypass grafts are infrequent. However, traditional management of dissection of axillary anastomosis for removal of the stump can be challenging. We report two patients with critical upper extremity ischemia secondary to stump syndrome and its successful management with endovascular techniques. METHODS: One hundred fifty-two patients underwent axillofemoral bypass grafting over 10 years from 1991-2001. Two patients from this series had acute ischemia involving the ipsilateral upper extremity of occluded axillofemoral bypass graft. Duplex ultrasound scans revealed occlusion of the axillofemoral bypass graft and acute occlusion of ipsilateral upper extremity arteries. Both patients underwent brachial artery exploration and embolectomy. Completion angiograms revealed persistent axillofemoral bypass graft stump as the source of embolus. The stump was obliterated with a 10-mm/40-mm Wallgraft introduced through the same arteriotomy made for brachial embolectomy. Transesophageal echocardiography and magnetic resonance angiography of the arch and great vessels were performed to exclude other sources of origin for the embolus. RESULTS: Both patients remained symptom-free and with patent stent grafts, as seen on duplex scans at 3, 6, and 9 months of follow-up. CONCLUSIONS: Upper extremity embolism is a rare complication after occlusion of axillofemoral bypass grafts. The endovascular approach to obliterate the stump of occluded axillofemoral bypass grafts is minimally invasive and an effective alternative treatment of this rare condition.
Aged↗
Protective effect of glycine in mesenteric ischemia and reperfusion injury in a rat model.
PURPOSE: Glycine has a protective effect in renal and skeletal muscle ischemia. The purpose of this study was to evaluate the effect of glycine in mesenteric ischemia and reperfusion injury in a rat model. METHODS: Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals received normal saline solution intravenously at 0.01 mL/g of body weight/h during ischemia and reperfusion. Treated animals received glycine at 0.5, 0.75, or 1.0 mg/g of body weight, dissolved in saline solution and infused at 0.01 mL/g/h for 2 hours. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were isolated. Sections of the segments stained with hematoxylin-eosin were subjected to histologic examination (as per modified Chiu grading system) and morphometric analysis consisting of measurement of bowel wall, muscularis and mucosal thickness, epithelial coverage, and villar circumference. Isometric tension responses to electrical stimulation (10, 30, 50, 100 Hz), high doses of potassium (120 mmol/L), and carbachol (0.1, 0.5, 1.0, 5.0 micromol/L) were recorded in a multimuscle chamber. Statistical analysis was performed with unpaired t test and one-way analysis of variance. RESULTS: The middle and distal segments of the small bowel in glycine-treated animals showed better histologic grade compared with saline solution-treated control rats (P <.05). At morphometric analysis, total thickness, mucosal thickness, and villar circumference ratio were well preserved in the middle and distal segments of the small bowel in the glycine-treated group (P <.05). No significant differences were observed in the proximal bowel segments between glycine-treated and control animals, because the proximal segment was not subjected to much ischemia. No differences were noted in percentage of epithelial coverage. Isometric tension responses evoked by electrical stimulation were greater (P <.05) in the middle and distal segments treated with glycine as compared with control segments. Carbachol-evoked contractions were stronger (P <.05) in the small bowel segments of animals treated with glycine. The responses evoked by 120 mmol/L of potassium were stronger in the distal segments of the small bowel in the glycine-treated group (P <.05). This cytoprotective effect of glycine was not dose-dependent. CONCLUSIONS: Glycine improved mucosal viability in the ischemia and reperfusion injury rat model. Mucosal thickness and villous circumference ratio were reliable objective parameters for evaluation of intestinal ischemia injury. Glycine improved the contractile responses of the bowel segments also, probably by altering the physiologic mechanisms underlying force generation. Further studies are required to elucidate the mechanism of the cytoprotective action of glycine.
Amino Acids↗
Dyeless vascular surgery.
PURPOSE: The morbidity associated with contrast-based diagnostics performed for preoperative evaluation prior to vascular intervention ranges from 1 to 21%. These complications range from minor hematomas to death. However, these exams are commonly felt to be a necessary step to completely evaluate the arterial tree before intervention is undertaken. Since this has varied from our experience, we reviewed our experience with repair of abdominal aortic aneurysms (AAAs), carotid endartectomy (CEA), and lower extremity revascularization performed without preoperative contrast studies. MATERIALS AND METHODS: During the last 10 years, we have performed 184 elective AAA repairs with abdominal-pelvis CAT scan without intravenous contrast as a preoperative study. During this same period of time, 903 CEAs were performed in 810 patients based solely on duplex ultrasonography or in combination with magnetic resonance angiography in cases where duplex ultrasonography was inconclusive (53 cases). Finally, over the last 30 months, we have performed 485 revascularizations in the lower extremity based solely on duplex ultrasonography mapping. Direct visualization of all major arteries from the distal aorta to the pedal vessels was performed using duplex imaging. Both the carotid duplex imaging and lower extremity duplex imaging were confirmed to have greater than 95 % positive predictive value during an initial phase of 50 cases confirmed with MRA and contrast angiography respectively. RESULTS: All cases of venous anomalies such as retrocaval left renal vein or left sided inferior vena cava in AAA patients were accurately identified and confirmed by intraoperative findings. No cases of horseshoe kidney were identified. Despite the presence of diminished femoral pulses in six patients, aortic reconstructions were performed with only duplex imaging. The 30 day mortality of AAA patients was 5% for elective repairs. In addition, no gross differences were appreciated with intraoperative findings of CEA as compared to preoperative duplex findings. However, in 5 cases CEA could not be performed due to extension of the lesion well above the available surgical exposure. The 30 day mortality of the CEA patients was 0.7% and the incidence of postoperative stroke or transient ischemic attack was 0.7%. Finally, in two early cases of lower extremity revascularization, the distal anastomosis was placed proximal to a lesion. This was appreciated during the procedure and corrected with a jump graft in each case. CONCLUSIONS: These data suggest that AAA repair, CEA, and lower extremity revascularization can be performed without contrast based preoperative studies and without compromise to evaluation of disease, patient safety or patency of bypass grafts.
Aortic Aneurysm, Abdominal↗
Postoperative anticoagulation in vascular surgery--Part two: A summary of lessons learned in our successful discharge planning experience using enoxaparin after vascular surgery.
Postoperative anticoagulation is not an uncommon scenario for patients undergoing vascular procedures. Additional postoperative length of stay (LOS) is necessary to achieve a therapeutic international normalized ratio with traditional protocols using unfractionated heparin. In part one of this 2-part article, low-molecular-weight heparin (LMWH), specifically enoxaparin, was shown to be a safe and effective alternative for anticoagulation after vascular surgical procedures. At the same time, its use can significantly reduce the average postoperative LOS after vascular procedures. This article describes a successful discharge planning experience using the LMWH enoxaparin after vascular procedures. We share our perspective on the role of the various members of the vascular surgical team as implemented in our acute care vascular surgical service clinical setting. Our discussion may offer ideas for consideration by vascular clinicians in their clinical settings.
Anticoagulants↗
Cerebral hyperperfusion syndrome after carotid endarterectomy: predictive factors and hemodynamic changes.
PURPOSE: It is believed that cerebral hyperperfusion syndrome (CHS) is caused by loss of cerebral autoregulation resulting from chronic cerebral ischemia and that factors including increased intraoperative cerebral blood flow, ipsilateral or contralateral carotid disease, and postoperative hypertension may cause CHS. We describe our experience with CHS, which diverges from published reports. MATERIALS AND METHODS: From March 2000 to February 2002 we performed 455 carotid endarterectomy (CEA) procedures in 404 patients at our institution. CHS developed 1 to 8 days (mean, 3.2 +/- 2.5 days) postoperatively in 9 patients (2%), 6 women and 3 men, whose age ranged from 52 to 84 years (mean, 69 +/- 8 years). Indications for surgery in 8 patients without neurologic symptoms were ipsilateral internal carotid artery (ICA) stenoses ranging from 70% to 99% (mean, 80% +/- 7%); the remaining patient had an ipsilateral stroke, with good clinical recovery, 7 weeks before CEA. Only 1 patient had significant contralateral ICA stenosis (70%). However, 5 patients had undergone contralateral CEA within the previous 3 months. CHS symptoms were severe headache in 5 patients, seizures in 3 patients (1 stroke), and visual disturbance and ataxia in 1 patient. All 404 patients (455 cases) underwent intraoperative and early (2 weeks) postoperative carotid artery duplex scanning. The 9 patients with CHS also underwent carotid artery duplex scanning at the time of the neurologic event. RESULTS: Mean intraoperative ICA volume flow (MICAVF) in the 9 CHS cases was not significantly different from that in the other 446 cases (170 +/- 47 mL/min and 182 +/- 81 mL/min, respectively). However, mean ICA volume flow (481 +/- 106 mL/min) and peak systolic velocity (PSV) (108 +/- 33 cm/s) for the 9 CHS cases measured at onset of symptoms were higher than those for the remaining 446 cases (267 +/- 87 mL/min and 80 +/- 26 cm/s, respectively) (P <.01). Of the 9 patients with CHS, only 3 had systolic blood pressures more than 160 mm Hg at onset of symptoms. Severity of ipsilateral and contralateral ICA stenoses was not significantly different between the 9 CHS cases and the remaining 446 cases. CONCLUSIONS: These data do not corroborate the common belief that CHS occurs preferentially in patients with severe ipsilateral or contralateral carotid disease, increased intraoperative cerebral perfusion, or severe hypertension. Recently performed contralateral CEA (<3 months) appears to be predictive of CHS.
Age Factors↗
Small popliteal artery aneurysms: are they clinically significant?
OBJECTIVE: We undertook this study to determine whether popliteal artery aneurysm diameter correlates with initial symptoms and presence of associated occlusive disease. METHODS: Duplex arteriography before infrainguinal revascularization in 500 lower extremities enabled diagnosis of 34 popliteal aneurysms in 25 patients (24 male, 1 female) over the last 4 years. Fourteen patients (41%) had no symptoms (group 1) and 20 (59%) had symptoms (group 2) of severe claudication (n = 8), acute ischemia (n = 6), rest pain (n = 2), and tissue loss (n = 4). We compared clinical presentation with popliteal artery diameter, prevalence of thrombosis, and presence of associated occlusive disease. RESULTS: Popliteal artery aneurysm diameter averaged 2.8 +/- 0.7 cm (range, 1.8-4.5 cm) in group 1 and 2.2 +/- 0.8 cm (range, 1.3-4.0 cm) in group 2 (P <.03). Popliteal aneurysm thrombosis was present in 7 of 20 limbs in group 2. Four of these patients also had ipsilateral superficial femoral artery thrombosis. Evaluation of the infrapopliteal arteries in group 1 showed three-vessel runoff in 7 limbs, two-vessel runoff in 3 limbs, one-vessel runoff in 2 limbs, and no vessel runoff in 2 limbs. However, all infrapopliteal arteries were either occluded or significantly stenotic in 14 limbs (70%). In group 2, one-vessel runoff was observed in 5 limbs, and two-vessel runoff in 1 limb. CONCLUSIONS: Smaller popliteal artery aneurysm was associated with higher incidence of thrombosis, clinical symptoms, and distal occlusive disease. Liberal use of duplex scanning in this setting may have accounted for the increased awareness that small popliteal artery aneurysms can thrombose and present with severe ischemia.
Adult↗
Glycine prevents the induction of apoptosis attributed to mesenteric ischemia/reperfusion injury in a rat model.
PURPOSE: We have previously demonstrated that glycine has a protective effect in mesenteric ischemia/reperfusion (I/R) injury. The purpose of this study was to elucidate the molecular mechanisms of the cytoprotective action of glycine. Because oxidative stress in I/R injury can lead to apoptosis, we examined the role of glycine in modulating the apoptotic signals in a rat mesenteric I/R injury model. METHODS: Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals (n=6) received normal saline intravenously at the rate of 0.01 mL/g/h during the ischemia and reperfusion period. Treated animals divided in 3 groups (n=6 in each) received glycine at a dose of either 0.5, 0.75, or 1.0 mg/g, infused at the rate of 0.01 mL/g/h during the reperfusion period. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were harvested for histopathology, TUNEL assay, and immunohistochemistry. Expression of apoptosis-related molecules, bcl-2, bax, caspase-3, death receptor, Fas, and death substrate, poly (ADP-ribose) polymerase (PARP) were studied. RESULTS: In glycine-treated animals, the middle and distal segments of the small intestine were well- preserved and showed better histologic grade and morphometric parameters as compared with saline controls (P<.05) in a dose-independent manner. There was increased apoptosis in saline controls as compared to the treated group (P<.01). Pro-apoptotic bax and caspase-3 were downregulated, whereas bcl-2 was upregulated in the glycine-treated animals (P<.02). Increased expression of death receptors and cleavage of PARP was observed in saline controls as compared to treated groups (P<.05). No significant differences were noted between the proximal bowel segments of treated and control animals. CONCLUSIONS: These data support the concept that I/R causes formation of death- inducing signal complexes, which may activate the sequential cleavage of caspases and death substrates. We have demonstrated that one of the mechanisms of the protective effect of glycine is the downregulation of the death-inducing signals and abrogation of the apoptotic cascade in this I/R injury model.
Animals↗
Lower extremity revascularization without preoperative contrast arteriography: experience with duplex ultrasound arterial mapping in 485 cases.
This study reviews our experience with duplex ultrasound arterial mapping (DUAM) for preoperative evaluation in 466 patients (262 men) who underwent 485 lower extremity revascularization procedures from January 1, 1998 to May 30, 2001. Preoperative imaging consisted of DUAM alone in 449 procedures and DUAM and contrast angiography (CA) in 36. An attempt to image from the distal aorta to the pedal arteries was made in all the patients. The selection of optimal inflow and outflow bypasses anastomotic sites was based on a schematic drawing following DUAM examination. Inflow disease was also assessed by intraoperative pressure gradient (IPG) between the distal anastomosis and radial arteries, and completion arteriography of the runoff vessels was obtained, which was correlated with the preoperative findings. Indications for surgery were severe claudication in 91 (19%) limbs, tissue loss in 197 (40%), rest pain in 113 (23%), acute ischemia in 46 (10%), popliteal aneurysm in 18 (4%), superficial femoral artery aneurysm in 1, abdominal aortic aneurysm with claudication in 1, and failing graft in 18 (4%). Age ranged from 30 to 97 years (mean 72 +/- 12 (SD) years) and risk factors such as diabetes, hypertension, use of tobacco, coronary artery disease, and end-stage renal disease were present in 45%, 45%, 44%, 44%, and 13% of the patients, respectively. One hundred twenty-one (25%) limbs had at least 1 previous ipsilateral revascularization. The mean DUAM time was 66 +/- 20 (SD) min (30-150 min). Additional preoperative imaging was deemed necessary in 36 cases due to extensive ulcers, edema, severe arterial wall calcification, and very poor runoff. The distal anastomosis was to the popliteal artery in 173 cases and to the tibial and pedal arteries in 255. Inflow procedures to the femoral arteries, embolectomy, thrombectomy, balloon angioplasty, and patch angioplasty accounted for the remaining 57 cases. Overall, 6-, 12-, and -24- month secondary patency rates were 86%, 80%, and 66%, respectively. This early experience shows that high-quality arterial ultrasonography performed by a highly skilled vascular technologist may represent an alternative to conventional arteriography for patients in need of lower extremity revascularization. Because of limitations inherent to the technique and very poor runoff observed on ultrasonographic examination, additional preoperative imaging procedure's are needed for certain patients.
Adult↗
Internal carotid artery flow volume measurement and other intraoperative duplex scanning parameters as predictors of stroke after carotid endarterectomy.
PURPOSE: Intraoperative duplex scanning (IDS) after carotid endarterectomy (CEA) has been shown to reliably identify major defects either by significant changes in peak systolic velocities or by B-mode imaging. To evaluate whether IDS could also predict postoperative strokes in technically flawless CEAs, we analyzed several hemodynamic parameters and correlated them with patient outcome. METHODS: From March 2000 to February 2001, 226 consecutive primary CEAs were performed in 208 patients (120 men). Of these, 153 lesions were asymptomatic. General anesthesia and synthetic carotid artery patches were used routinely. Intraluminal shunts were used when internal carotid artery (ICA) back-pressures were <50 mm Hg (35% of cases). IDS consisted of B-mode and color-flow imaging and spectral analyses of the common, external, and internal carotid arteries. Volume flows were measured three times, and the mean flow rate was used for this study. RESULTS: The first set of data was analyzed when the twenty-ninth patient had the second immediate postoperative stroke. It was noted that the two patients who had postoperative strokes had mean ICA volume flows (MICAVF) of 48 mL/min and 85 mL/min. Only two additional patients had MICAVF <100 mL/min. The remaining 25 cases had MICAVF ranging from 102 to 299 mL/min, with a mean of 165 +/- 57 mL/min (+/-SD) (P <.02). Although there was a significant correlation between MICAVF and ICA peak systolic velocity (P <.01), the latter was not found to be a significant predictor of postoperative stroke. Moreover, end-diastolic velocities, resistive index, ICA diameter, and ICA back-pressure also did not correlate with neurologic events. These findings led us to change our protocol for patients with MICAVF <100 mL/min. This included a repeat set of volume flow measurements after 15 to 20 minutes, withholding the reversal of heparin, and the liberal use of completion arteriography. Of the following 197 CEAs, 26 (13%) were found to have MICAVF <100 mL/min (range 55 to 99 mL/min; mean 79 +/- 18 mL/min). Of these, five had arteriography that documented spasm of the intracranial portion of the ICA in four and a small-diameter ICA (<2 mm) in one. Except for the five cases, the remaining 21 cases had MICAVF >100 mL/min (range 105 to 158 mL/min, mean 127 +/- 20 mL/min [+/-SD]) on repeat study. Four patients with persistent ICA low flow (70 to 99 mL/min) were treated with postoperative anticoagulation. One of the last 197 patients had a stroke caused by hyperperfusion syndrome 2 weeks after operation. Overall, six of 226 cases (2.7%) required revision on the basis of abnormal B-mode imaging results or peak systolic velocities >150 cm/s. There were two common carotid artery flaps, two ICA stenoses, one ICA flap, and one localized thrombus. All six were successfully revised and had repeat normal IDS study results, and none of these patients had a postoperative stroke. CONCLUSIONS: IDS is helpful in identifying residual lesions or defects that may contribute to postoperative neurologic deficits. MICAVF <100 mL/min are suggestive of spasm that could lead to thrombus formation and stroke, particularly in the presence of synthetic patches. We suggest that heparin reversal should not be used unless ICA flow rates are >100 mL/min. ICA spasm is short lived in most patients undergoing CEA.
Aged↗
Pseudo-occlusions of the internal carotid artery: a rationale for treatment on the basis of a modified carotid duplex scan protocol.
PURPOSE: We report on a modified duplex scanning technique that may be a means of detecting a patent internal carotid artery (ICA) previously believed to be occluded by means of magnetic resonance angiography (MRA), standard duplex protocols, or both. In addition, we attempted to develop selection criteria for operability in this setting, on the basis of the lumen diameter and wall thickness of the post-stenotic ICA segment. METHOD: In the past 22 months, 17 patients (12 men; 5 women) with ICA occlusions reported by means of MRA (10 patients) or by means of duplex scanning (7 patients) were found to have patent arteries when subjected to this duplex scanning protocol: (1) the use of low pulse repetition frequency (150-350 Hz), maximal persistence, and sensitivity of color and power angiography modes; (2) the use of an 8-MHz to 5-MHz probe as a means of visualizing the most distal extracranial segment of the ICA; and (3) measurements of the lumen diameter and wall thickness of the post-stenotic ICA. The age of patients ranged from 53 to 80 years (mean age, 71 years). Seven patients (41%) had no symptoms. RESULTS: Extremely low peak systolic and end-diastolic velocities were detected distal to the stenotic segment in the ICA in all cases, and they varied from 5 to 30 cm/s (mean, 14 plus minus 8 cm/s) and 0 to 8 cm/s (mean, 4.5 plus minus 2.0 cm/s), respectively. The luminal diameter of the post-stenotic ICA varied from 0.7 to 3.6 mm (mean, 2.0 plus minus 1.1 mm), and the wall thickness ranged from 0.6 to 1.4 mm (mean, 0.9 plus minus 0.3 mm) in all patients. Twelve patients (71%) were examined with the intent of performing an endarterectomy. Of these, eight patients (47%) underwent successful operations with patches (3 vein; 5 synthetic), and four (29%) were found to have unreconstructable disease. The ICA lumen diameter and wall thickness in all eight patients who underwent endarterectomies were 2 mm or larger and 1 mm or thinner, respectively, whereas they were smaller than 2 mm and thicker than 1 mm, respectively, in the remaining four patients (P <.01). The last five patients were observed because they had small ICAs (lumen <2 mm) with thickened walls (>1 mm). Intraoperative and early postoperative duplex scanning examinations were performed in the eight ICAs that were successfully reconstructed. In these patients, the ICA lumen diameter increased from a mean of 2.9 plus minus 0.4 mm preoperatively to a mean of 4.4 plus minus 0.3 mm 2 weeks postoperatively (P <.001). Intraoperative ICA flow volumes were also measured after the endarterectomy, and they varied from 55 to 242 mL/min (mean, 115 plus minus 53 mL/min) and ranged from 122 to 220 mL/min (mean, 159 plus minus 34 mL/min) 2 weeks postoperatively. One patient who did not undergo surgical exploration died of chronic renal failure and congestive heart failure within the first month of follow-up. The remaining 16 patients had no neurological symptoms and were alive after a follow-up period of 2 to 22 months (mean, 8 plus minus 5 months). CONCLUSION: The proposed duplex protocol appears to be an effective means of identifying some patients with patent ICAs that were believed to be occluded by means of standard examinations. In addition, such patients may be candidates for an endarterectomy if the ICA post-stenotic lumen diameter is 2 mm or larger and the wall thickness is 1 mm or thinner.
Aged↗
Recommended standards for reports dealing with arteriovenous hemodialysis accesses.
The incidence rate of treated end-stage renal disease in the united states is 180 per million and continues to rise at a rate of 7.8% per year. Arteriovenous hemodialysis access (AV access) creation and maintenance are two of the most difficult issues associated with the management of patients on hemodialysis. The 1-year complication rate of a primary prosthetic AV access for hemodialysis ranges from 33% to 99%. Various investigators report on patency and complications of AV access. However, it is rather difficult to compare outcomes because of the wide variety of access materials, configurations, locations, risk factors, and quality of inflow and outflow vessels. Although there have been reporting standards for dialysis access endovascular interventions and for central venous access placement, standards regarding surgical access placement and its revision are lacking. The "Dialysis Outcome Quality Initiative," published by the National Kidney Foundation, provides recommendations for optimal clinical practices aimed at improving dialysis outcome and patient survival. This reporting standards document is not meant to be a "practice guidelines" or "best practices" document. Rather, the purpose of this document is to provide standardized definitions related to AV access procedures and to recommend reporting standards for patency and complications, to be used by surgeons, nephrologists, and interventional radiologists, that will permit meaningful comparisons among AV access procedures. The terms, definitions, and categories featured in this article have been approved by the Committee on Reporting Standards of the Society for Vascular Surgery and the American Association for Vascular Surgery and should be observed in preparing manuscripts on AV accesses for submission to the Journal Of Vascular Surgery.
Arteriovenous Shunt, Surgical↗