Biomedical subjects

Anil Hingorani

Publications and source records attributed to Anil Hingorani.

At least 19 recordsLinked to original sources

PubMed2006

Morbidity and mortality associated with brachial vein thrombosis.

We have noted a significant incidence of pulmonary embolism (PE) and mortality associated with upper extremity deep venous thrombosis (UEDVT). Since there is an association between site of lower extremity DVT (LEDVT) and PE, we hypothesized that there might also be a correlation between site of UEDVT and PE with associated mortality. To further elucidate this hypotheses, we analyzed the mortality and incidence of PE diagnosed with subclavian/axillary/internal jugular vein thrombosis during an 11-year period at our institution and compared the data to those of patients diagnosed with brachial DVT. We studied 598 patients diagnosed with acute internal jugular, subclavian, axillary, or brachial DVT by duplex scanning. The patients were divided into three groups based on the most proximal location of the thrombus: group I, UEDVT involving the subclavian or axillary veins (n = 467); group II, isolated internal jugular DVT (n = 80); group III, brachial DVT alone (n = 52). Mortality rates at 2 months were 29%, 25%, and 21% for each group, respectively. The number of patients diagnosed with PE by ventilation/perfusion scans in groups I, II, and III, respectively, were 5%, 6.25% and 11.5% (p = 0.13). Furthermore, stratification by risk factors failed to demonstrate factors associated with increased 2-month mortality. Contrary to the initial hypothesis of a relationship between the site of thrombosis and the incidence of PE and mortality, these data demonstrated no statistical differences in mortality or incidence of PE among the groups studied. Additionally, these data suggest that brachial vein thrombosis is a disease process related to comparable associated mortality and morbidity similar to other forms of UEDVT. Based on these data, we suggest that UEDVT may be thought of as a marker for the severity of systemic illness of the patient rather than just as a cause of venous thromboembolism.

Adolescent↗

PubMed2005

Risk factors for mortality in patients with upper extremity and internal jugular deep venous thrombosis.

OBJECTIVE: To elucidate the natural history of upper extremity deep venous thrombosis (UEDVT), we examined factors that may contribute to the high mortality associated with UEDVT. METHODS: Five hundred forty-six patients were diagnosed with acute internal jugular/subclavian/axillary deep venous thrombosis from January 1992 to June 2003 by duplex scanning at our institution. There were 329 women (60%). The mean age +/- SD was 68 +/- 17 years (range, 1-101 years). Risk factors for UEDVT were the presence of a central venous catheter or pacemaker in 327 patients (60%) and a history of malignancy in 119 patients (22%). Risk factors for mortality within 2 months of the diagnosis of UEDVT that were analyzed included age, sex, presence of a central venous catheter or pacemaker, history of malignancy, location of UEDVT, concomitant lower extremity deep venous thrombosis, systemic anticoagulation, placement of a superior vena caval filter, and pulmonary embolism. RESULTS: The overall mortality rate at 2 months was 29.6%. The number of patients diagnosed with pulmonary embolism by positive ventilation/perfusion scan or computed tomographic scan was 26 (5%). The presence of a central venous catheter or pacemaker ( P < .001), concomitant lower extremity deep venous thrombosis ( P = .04), not undergoing systemic anticoagulation ( P = .002), and the placement of a superior vena caval filter ( P = .02) were associated with mortality within 2 months of the diagnosis of UEDVT by univariate analysis. Pulmonary embolism ( P = .42), sex ( P = .65), and a history of malignancy ( P = .96) were not. CONCLUSIONS: These data suggest that the high associated mortality of UEDVT may be due to the underlying characteristics of the patients' disease process and may not be a direct consequence of the UEDVT itself.

Adolescent↗

PubMed2005

Overexpression of transforming growth factor-beta1 correlates with increased synthesis of nitric oxide synthase in varicose veins.

INTRODUCTION: Transforming growth factor-beta 1 (TGF-beta 1 ) is known to maintain a balance between apoptosis and cellular dysfunction and therefore may have a pivotal role in vessel remodeling during pathogenesis of vascular disorders. We previously demonstrated that inducible nitric oxide synthase (iNOS) mediates signal transduction in vascular wall during the development of varicose veins. Currently, we investigated the expression and correlation of TGF-beta 1 , iNOS, monocyte/macrophage infiltration, and loss of vascular smooth muscle cells (VSMCs), in a series of normal and varicose vein specimens. METHODS: Twenty varicose vein specimens were retrieved from 20 patients undergoing lower-extremity varicose vein excision, and 27 normal greater saphenous vein segments (controls) were obtained from 27 patients undergoing infrainguinal arterial bypass surgery. Principal risk factors (diabetes mellitus, hypertension, tobacco abuse) were also compared. Varicose vein segments were separated into tortuous and nontortuous regions based on their macroscopic and microscopic morphology. VSMC actin, CD68 + monocytes/macrophages, iNOS, and TGF-beta 1 , were examined by immunohistochemistry, immunoblotting, and real-time reverse transcriptase polymerase chain reaction. RESULTS: According to the CEAP classification for chronic lower extremity venous disease, most of the patients were in class 2 for clinical signs of the disease (n = 11). Mean ages were 53.6 +/- 4.7 years for the varicose vein group and 56.5 +/- 4.4 years for the controls. The gender distribution was same in both groups. Immunoreactivity to TGF-beta 1 and iNOS was significantly different in the tortuous regions of the varicose veins compared with nontortuous regions (P < .01). Not only was a significantly higher expression of iNOS noted in the varicose vein group (P < .001), but a differential expression of iNOS was also observed in the tortuous and nontortuous portions of the varicose veins. Significant overexpression of TGF-beta 1 (P < .01) that correlated with overproduction of iNOS and with increased presence of CD68 + monocytes/macrophages was observed in the varicose vein walls compared with normal veins. CONCLUSIONS: This is the first evidence of TGF-beta 1 , as well as iNOS, being differentially upregulated in nontortuous and tortuous segments of varicose veins. The increased expression of TGF-beta 1 and presence of macrophages, correlating with overproduction of iNOS, may be associated with varicosity development and deserves further study. CLINICAL RELEVANCE: The pathogenesis of varicose veins, the most common manifestation of chronic venous disease, is debatable. Elucidation of mechanisms involved in the disease process is the first step to improved therapeutic modulations. Towards this goal, the relationship between NO production and TGF-beta 1 in the molecular pathophysiology of chronic venous disease was investigated. The data identify for the first time, an important role for TGF-b1-iNOS-monocyte/macrophage signaling in the etiology of varicosities. Furthermore, we determine if there are any significant differences within the varicose vein group itself based on regional differences, by classifying the varicose tissues into tortuous and non-tortuous segments.

Blotting, Western↗

PubMed2005

Mini skin incision for carotid endarterectomy (CEA): a new and safe alternative to the standard approach.

PURPOSE: Patients requiring surgery are naturally attracted to shorter incisions because they tend to cause less pain and are esthetically more appeasing. To substantially shorten the length of standard skin incisions (4 to 7 inches) for carotid endarterectomy (CEA), we used preoperative duplex scanning to outline the carotid bifurcation as well as to determine the extent of disease in both the internal and common carotid arteries. METHODS: During the last 21 months, 265 consecutive primary CEAs were performed in 253 patients (mean age 72 +/- 10 years) at a single institution. Of these, 142 were men (56%). Hypertension, coronary artery disease, diabetes mellitus, smoking, and chronic renal failure were present in 81%, 44%, 43%, 28%, and 19% of the patients, respectively. Neurologically asymptomatic patients accounted for 71% of the cases. All patients received general anesthesia. Duplex-assisted skin markings of the diseased carotid artery were performed after proper patient positioning on the operating table. Synthetic patches were routinely used, and intraluminal shunts were deemed necessary by low stump pressures in 64 cases (24%). Completion duplex scanning was performed in all cases. RESULTS: The length of the longitudinal skin incision varied from 0.8 to 3.5 inches (average 1.4 +/- 0.5 inches). It was < or = 1 inch in 56 cases (21%), 1.1 to 1.5 inches in 110 (42%), 1.6 to 2 inches in 85 (32%), and 2.1 to 3.5 inches in the remaining 14 cases (5%). Intraluminal shunts were required in 9 (16%), 18 (16%), 29 (34%), and 8 (57%) of the cases, respectively. Incisions were longer in cases requiring an indwelling shunt (1.6 +/- 0.6 inches vs 1.4 +/- 0.4 inches) (P < .0001). The average patch length was 1.3 +/- 0.3 inches (range, 0.7 to 2.6 inches). The skin incision averaged 1.54 +/- 0.45 inches for the first 133 cases and 1.35 +/- 0.45 inches for the remaining 132 cases (P < .0001). Technical defects occurred in 10 cases (3.8%). The overall incidence of ipsilateral stroke and death was 1.9% and 0%. There were no technical defects or strokes in patients with the shortest incisions (< or = 1 inch). Overall, there were three transitory peripheral nerve injuries (1.1%). A comparative analysis with 265 consecutive CEAs performed immediately before this series without duplex-assisted skin markings revealed no significant differences in age (71 +/- 11 years), incidence of neurologically symptomatic patients (26%), sex (60% men), shunt use (24%), and major technical defects (3%). Also, postoperative transitory peripheral nerve injury (0.8%), stroke (0%), and death (0%) were not significantly different from the duplex-assisted group. It is of interest to note that none of the former cases was performed with a skin incision < or = 2 inches. CONCLUSION: Most CEAs (95%) can safely be performed with < or = 2-inch skin incisions. Pre-CEA duplex-assisted skin marking is a novel approach that confirms the side of the operation, localizes the disease, and minimizes the magnitude of the operation via shorter, more esthetically pleasing incisions.

Aged↗

PubMed2004

A comparison of magnetic resonance angiography, contrast arteriography, and duplex arteriography for patients undergoing lower extremity revascularization.

The objective of this study was to compare magnetic resonance angiography (MRA), contrast arteriography (CA), and duplex arteriography (DA) for defining anatomic features relevant to performing lower extremity revascularizations. From March 1, 2001 to August 1, 2001, 33 consecutive inpatients with chronic lower extremity ischemia underwent CA, MRA, and DA before undergoing lower extremity revascularization procedures. The reports of these tests were compared prospectively and the differences in the aortoiliac segment, femoral-popliteal, and infrapopliteal segments were noted. The vessels were classified as mild disease (<50%), moderate disease (50-70%), severe disease (71-99%), and occluded. These studies and treatment plans based on these data were compared. During this time period, 11 patients were not able to undergo MRA and therefore were excluded from the study. Thirty-three patients were included in this study. These patients underwent 35 procedures, as 2 patients underwent bilateral procedures. The mean age of the 33 patients was 76+/-10 years (SD). Indications for the procedures included gangrene (20), ischemic ulcer (8), rest pain (4), and severe claudication (1). Patients' medical history included diabetes mellitus (25), hypertension (20), and end-stage renal disease (5). No differences were noted between intraoperative findings and CA in this series. Two of the three differences between DA and CA were felt to be clinically significant whereas 9 of the 12 differences between MRA and CA were felt to be clinically significant. On the basis of these data in this series, MRA does not yet seem to be able to obtain adequate data on infrapopliteal segments, at least not for this highly selected population. When severe tibial calcification or very low flow states are identified, CA may be necessary for patients undergoing DA.

Aged↗

PubMed2004

Role of duplex arteriography as the sole preoperative imaging modality prior to lower extremity revascularization surgery in diabetic and renal patients.

The limitations and complications associated with contrast angiography (CA) prior to lower extremity revascularization have led to an increased interest in duplex arteriography (DA) as a potential replacement. We report our experience with DA in patients with diabetes and/or chronic renal insufficiency (CRI) that would particularly benefit from a noninvasive approach to preoperative evaluation of the arterial tree. From January 1998 to November 2000, DA was performed in 145 patients with diabetes mellitus and/or CRI prior to 180 arterial reconstructions. One hundred twenty-one procedures were performed on 91 patients with diabetes alone, 41 on 33 patients with diabetes and CRI, and 18 on 15 patients with CRI alone. Patient ages ranged from 36 to 98 years (mean 72 +/- 12 years). Indications for surgery were severe claudication in 33 (18%), rest pain in 37 (21%), nonhealing ischemic ulcers in 52 (29%), and limb gangrene in 58 (32%). Optimal inflow and outflow anastomotic sites were selected according to a diagram based on DA that included arterial tree imaging from mid-aorta to the pedal vessels. Preoperative contrast arteriography was performed in 16 cases (9%) because of extremely poor runoff based on DA and limited visualization of outflow vessels. The distal anastomosis was to the popliteal artery in 89 cases (49%) and to the tibial and pedal arteries in 91 (51%). Intraoperative findings confirmed the preoperative DA results with the exception of one (0.6%) where the distal anastomosis was placed proximal to a significant stenosis requiring an extension graft. The use of DA presents a safe and reliable option to prebypass CA for many patients with diabetes or CRI. The ease of use and favorable patient outcomes achieved by this imaging modality may rival the use of CA for these patients.

Aged↗

PubMed2004

Magnetic resonance angiography versus duplex arteriography in patients undergoing lower extremity revascularization: which is the best replacement for contrast arteriography?

OBJECTIVE: In an effort to explore alternatives to contrast material-enhanced arteriography, we compared magnetic resonance angiography (MRA) and duplex arteriography (DA) with contrast arteriography (CA) for defining anatomic features in patients undergoing lower extremity revascularization. METHODS: From August 1, 2001, to August 1, 2002, 61 consecutive inpatients (64 limbs) with chronic lower extremity ischemia underwent CA, MRA, and DA before undergoing lower extremity revascularization procedures. The reports of these tests and images were compared prospectively, and the differences in the iliac, femoropopliteal, and infrapopliteal segments were noted. The vessels were classified as mildly diseased (<50%), moderately diseased (50%-70%), severely diseased (71%-99%), or occluded. The studies and treatment plans based on these data were compared. RESULTS: Mean patient age was 76 +/- 10 years (SD). Indications for the procedures included gangrene (43%), ischemic ulcer (28%), rest pain (19%), severe claudication (9%), and failing bypass (1%). During this period 35 patients were ineligible for the protocol, because they could not undergo MRA (n=27) or angiography (n=8). Of the total 192 segments in the 64 patients (iliac, femoropopliteal, tibial), 17% were not able to be fully assessed with DA, and 7% with MRA. Disagreements with CA and DA were found in the iliac, femoropopliteal, and tibial segments in 0%, 7%, and 14% of cases, respectively, and between CA and MRA in 10%, 26%, and 42% of cases, respectively. Two of 9 differences (22%) between DA and CA were thought to be clinically significant, and 28 of 45 differences (62%) between MRA and CA were thought to be clinically significant. CONCLUSIONS: A review of the data obtained in this series indicates that MRA does not yet seem to yield adequate data, at least in this highly selected population at our institution. When severe calcification is identified, CA may be necessary in patients undergoing DA.

Aged↗

PubMed2004

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2003

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↗

PubMed2002

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↗

PubMed2002

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↗