Marshall E. Benjamin

Regression of proximal deep venous thrombosis is associated with fibrinolytic enhancement

PURPOSE Recanalization after acute lower limb deep venous thrombosis (DVT) is well documented, but the precise mechanism and timing of these events has not been well characterized. Regression of DVT has been presumed to result from activation of the endogenous fibrinolytic system. This study was performed to compare measurements of the enzymatic components of the intrinsic fibrinolytic system (tissue plasminogen activator [tPA], plasminogen activator inhibitor [PAI-1]) with the observed morphologic changes in thrombosed venous segments using venous duplex ultrasound scanning (VDUS) at intervals after diagnosis of acute DVT. METHODS Nineteen patients with acute DVT underwent serial VDUS to assess regression of thrombus at intervals of 1 to 2 weeks, 3 to 6 weeks, 8 to 12 weeks, and 24 to 36 weeks. The extent of thrombus in each limb was quantitated at each interval by VDUS of the residual thrombus present in each of five major axial venous segments: the common femoral, superficial femoral, profunda femoris, popliteal, and tibial veins. Thrombus scores for the group at each interval were compared with baseline scores at diagnosis to calculate the percent residual thrombus. Endogenous fibrinolytic activity was determined at the same intervals by serologic assay of the biologic activities of tPA and its inhibitor PAI-1. RESULTS Thrombus regression was evident by VDUS at 1 to 2 weeks and progressed such that only 26% of residual thrombus remained at 24 to 36 weeks. Complete resolution of thrombus occurred in 10 of 18 patients (56%) who completed the 9-month study. Baseline mean tPA activity was 0.60 +/- 0.07 IU/ml and increased to 1.31 +/- 0.26 IU/ml at 1 to 2 weeks (p = 0.014). tPA activity remained significantly elevated through the 8 to 12 week interval and returned to baseline at 24 to 36 weeks. PAI-1 activity was elevated relative to an age-matched population at baseline (23.1 +/- 1.8 AU/ml) but remained unchanged throughout the study period. Progression of thrombus was observed in three patients (15.8%). Patients who experienced propagation of thrombus did not have the increased tPA activity that appeared to mark activation of intrinsic fibrinolysis. CONCLUSIONS Regression of acute DVT begins early and continues for at least 9 months. It is accompanied by significant enhancement of the endogenous fibrinolysis, which appears to be primarily mediated by increased tPA activity. Patients who have thrombus propagation in spite of standard antithrombotic therapy may have failure of activation of endogenous fibrinolysis.

Renal artery fibromuscular dysplasia: Results of current surgical therapy

PURPOSE This retrospective review describes current surgical management of renal artery (RA) fibromuscular dysplasia (FMD) to define contemporary clinical characteristics and surgical results in patients over the age of 21 years. METHODS From January 1987 through March 1994, 40 consecutive adults with hypertension had operative RA repair of FMD at our center and form the basis of this report. From histologic and angiographic appearance, FMD was classified with regard to specific type, noting the presence of RA dissections, RA macroaneurysms and branch RA involvement. Associations between blood pressure response to operation and patient age, duration of hypertension, presence of extrarenal atherosclerosis, presence of branch renal artery disease, and primary or secondary procedure were examined. Clinical characteristics and blood pressure response in these contemporary patients were compared with the results reported from an earlier surgical series. RESULTS Unilateral RA repair was performed in 34 patients, and bilateral procedures were required in six patients. Branch renal artery repair was performed in 28 instances, including ex vivo RA repair in 11 patients. There were no perioperative or follow-up deaths; however, three RA grafts (7%) failed within 30 days of operation. Initial blood pressure response was considered cured in 33%, improved in 57%, and failed in 10%. Analysis demonstrated that patients older than 45 years of age had a significantly decreased rate of hypertension cure compared with younger patients; among patients younger than 45 years of age, duration of hypertension was inversely related to cure. Compared with earlier surgical series, our current group of patients was significantly older, with more frequent branch renal artery involvement and extrarenal atherosclerosis, and demonstrated decreased rate of hypertension cure. CONCLUSION A beneficial blood pressure response is currently observed in most selected patients after surgical correction of RA-FMD. Compared with earlier series, however, the present day patient differs in many respects, including a significantly decreased chance for hypertension cure after surgical repair.

Combined aortic and renal artery surgery. A contemporary experience.

PURPOSE This retrospective study examines results with simultaneous aortic and renal artery repair in 133 consecutive hypertensive patients. These results are compared with consecutive patient groups undergoing aortic reconstruction alone (269 patients) or renal artery reconstruction alone (182 patients). METHODS From January 1987 through July 1995, 61 women and 72 men (mean age, 62.5 years) underwent combined repair of renal artery and aortic disease (abdominal aortic aneurysm [AAA]: 47 patients; occlusive disease: 86 patients; both: 12 patients). All patients were hypertensive (mean blood pressure: 194/103 mmHg; mean medications: 2.4). Evidenced by serum creatinine levels > or = 2.0 mg/dL, 46 patients (35%) had significant renal dysfunction (mean serum creatinine level: 3.78 mg/dL; range 2.0-10.6 mg/dL, including 7 dialysis-dependent patients). Aortic replacements (29% tube grafts; 71% bifurcated grafts) were combined with unilateral renal artery repair in 47% of patients; 53% had bilateral repair. Preoperative clinical features and perioperative mortality were compared with those groups having isolated aortic and renal repairs. RESULTS There were seven perioperative deaths (5.3%) after combined repair, which differed significantly from isolated aortic repair (mortality: 0.74%; p = 0.005), but did not reach statistical significance when compared with the isolated renal artery group (mortality: 1.65%; p = 0.145). Risk analysis did not reveal a significant association between preoperative clinical features and mortality in either the combined repair group or the groups undergoing renal repair alone or aortic repair alone. Among survivors in the combined group, a favorable hypertension response was observed in 63%. This differed significantly from the group receiving renal repair alone (90% cured/improved; p < 0.001). Based on a 20% decrease in serum creatinine levels, excretory renal function was improved in 33% of patients with combined repair, including four of the seven patients removed from hemodialysis. There were eight late deaths in the combined group. CONCLUSIONS Our experience suggest that contemporary perioperative mortality for combined aortic and renal repair has improved compared with earlier reports; however, perioperative mortality for simultaneous reconstruction remains greater than repair of aortic disease alone. Moreover, a lower rate of favorable hypertension response was observed after combined correction compared with renal artery repair alone. These differences suggest that aortic and renal artery repair should only be combined for clinical indications rather than for prophylactic repair of clinically silent disease.

Duplex ultrasound insertion of inferior vena cava filters in multitrauma patients

BACKGROUND Techniques for placement of inferior vena cava (IVC) filters have undergone continued evolution from open surgical exposure of the venous insertion site to percutaneous insertion in most cases today. However, the required transport either to an operating room or interventional suite can be complex and potentially hazardous for the multiply injured trauma patient who may require ventilator support, controlled intravenous infusions, or skeletal immobilization. Increased experience with color-flow duplex scanning for routine IVC imaging and portability of ultrasound equipment have suggested the usefulness of duplex-guided IVC filter insertion (DGFI) in critically ill trauma and intensive care unit (ICU) patients. METHODS A total of 25 multitrauma/ICU patients were considered for DGIF. Screening color-flow duplex scans were performed on all patients, and obesity or bowel gas prevented ultrasound imaging in 2 cases, leaving 23 patients suitable for DGFI. In each case, the IVC was imaged in the transverse and longitudinal planes. The right renal artery was identified as it passed posterior to the IVC and was used as a landmark of the infrarenal segment of the IVC. All procedures were performed at the bedside in a monitored ICU setting using percutaneous placement of titanium Greenfield filters. Duplex scanning after insertion was used to document proper placement, and circumferential engagement of the filter struts in the IVC wall. An abdominal radiograph was also obtained in each case to confirm proper filter location. Duplex ultrasound imaging was repeated within 1 week of insertion to assess IVC and insertion site patency. RESULTS DGFI was successful in all cases. The filter was deployed at a suprarenal level in one case, as was recognized at the time of postprocedural scanning. Three patients died as a result of their injuries but there were no pulmonary embolism deaths. Repeat duplex scanning was obtained in 17 patients, and revealed no case of IVC or insertion site thrombosis. CONCLUSIONS Vena caval interruption can be safely performed under ultrasound guidance in a monitored, ICU environment. In selected multiply injured trauma patients, this will reduce the risk, complexity and cost of transport for these critically ill patients. DGFI also reduces procedural costs compared with an operating room or interventional suite, and eliminates intravenous contrast exposure. Preprocedural scanning is essential to identify patients suitable for DGFI, and careful attention must be paid to the known ultrasonographic anatomical landmarks.

Fenoldopam Infusion Associated with Preserving Renal Function After Aortic Cross-Clamping for Aneurysm Repair

Background: Cross-clamping of the descending aorta during operative repairs causes sudden, significant reductions in renal function that may persist well beyond arterial clamp release. Commonly used agents, such as dopamine and mannitol, have not consistently affected renal outcome in these high-risk patients. Fenoldopam mesylate is a novel, highly selective dopamine type-I agonist that preferentially dilates the renal and splanchnic vasculature, but has not been investigated in patients undergoing prolonged aortic clamping for whom adverse renal outcomes should be more likely. Methods and Results: Twenty-two adult patients without significant pre-existing renal dysfunction and presenting for elective repairs of abdominal aortic aneurysms were studied. Fenoldopain mesylate was infused after obtaining baseline values ranging from 0.1 to 1.0 pg/kg/min for the first 24 hours postoperatively to maintain mean arterial pressure ±25% baseline. Serial renal function indices, including creatinine clearance and electrolyte fractional excretions, were measured at baseline, at aortic clamping and unclamping, and post-clamp release, and were estimated through hospital discharge. Creatinine clearance fell during abdominal exploration and clamping, reaching a nadir with clamp removal. Partial recovery occurred by 2 hours after clamp removal, and returned to baseline values by postoperative day 1 and thereafter. Fractional excretions rose rapidly throughout the operative phase. Total fenoldopam dose was directly related to the baseline creatinine clearance; after clamp removal, creatinine clearance was directly related to the mean arterial pressure at the lowest dose of fenoldopam, and inversely related to the mean arterial pressure at clamp release. Conclusions: In elderly patients with severe vascular disease undergoing aneurysmal repairs, the use of a fenoldopam infusion in this open-label, uncontrolled trial was associated with a relatively rapid return of renal function to baseline values, despite profound decreases during aortic cross-clamping. Further studies will be necessary to investigate how fenoldopam infusions compare with traditional therapies.

Can intrarenal duplex waveform analysis predict successful renal artery revascularizaion

PURPOSE No currently available noninvasive test can preoperatively predict a successful outcome to renal revascularization. Resistance measurements from the renal parenchyma obtained with duplex sonography reflect the magnitude of intraparenchymal disease, and patients with extensive intrarenal disease may respond less favorably to revascularization. To address this question, we reviewed our (primarily) operative experience in patients undergoing renal artery revascularization, and compared the blood pressure (BP) and renal function response with resistance measurements obtained from the kidney both before and after revascularization. METHODS During a 56-month period, 31 consecutive renal artery revascularizations (25 surgical and 6 percutaneous angioplasties) were performed in 23 patients (21 atherosclerotic, 2 fibromuscular dysplasia). Duplex sonography was performed in each patient before and after revascularization, and parenchymal diastolic/systolic (d/s) ratios were calculated. BP and renal function response to intervention were compared with measurements of intrarenal flow patterns before and after revascularization. RESULTS Mean parenchymal peak systolic velocity was significantly higher after repair in all patients (pre-repair: 19.5 +/- 1.3, postrepair: 27.2 +/- 1.7; P < .0001). Despite this, there were no statistical differences between preoperative and postoperative parenchymal d/s ratios. A favorable (cured or improved) BP response was seen in 81% (17 of 21) of revascularizations performed for hypertension. Among these successes, parenchymal d/s ratios were in the normal range (ie, > or = 0.30) both before and after repair (mean prerepair: 0.34 +/- 0.03, mean postrepair: 0.31 +/- 0.03; not significant). In 4 patients in which BP failed to improve after intervention, the d/s ratio was abnormal before surgery (< 0.3), and remained so after revascularization (mean preoperative d/s ratio: 0.18 +/- 0.04, mean postoperative d/s ratio: 0.11 +/- 0.04; P = .003). Mean preoperative parenchymal d/s ratios were significantly higher in all patients with a successful BP response when compared with failures (P = .048). Similarly, among patients with single artery repairs, mean preoperative d/s ratios approached significance in successes vs. failures (success: 0.40 +/- 0.03, failure: 0.21 +/- 0.03; P = .054). A decrease in serum creatinine greater than or equal to 20% was seen in 8 of 18 patients (44%) with ischemic nephropathy. These patients also had normal d/s ratios preoperatively (mean 0.39 +/- 0.04), whereas the 10 patients who failed to improve had significantly lower ratios (mean 0.24 +/- 0.03; P = .041). Kidney length did not correlate with d/s ratio. CONCLUSION Although we do not believe that duplex sonographic measurement of intrarenal flow patterns alone is an accurate means of assessing main renal artery occlusive disease, the resistive indices seem to reflect the magnitude of intraparenchymal disease, and thus may provide important prognostic information for patients undergoing surgical revascularization. Our data suggest that a preoperative d/s ratio below 0.3 correlates with clinical failure relative to BP and renal function responses.

The Bedside Insertion of Inferior Vena Cava Filters Using Ultrasound Guidance

Since the introduction of inferior vena cava (IVC) filters more than 30 years ago, there has been a steady improvement in the design, ease, and safety of the delivery systems. Today, all of the commonly used filters can be placed via a peripheral vein by using standard percutaneous Seldinger technique. However, this typically requires fluoroscopy, intravenous contrast agents, radiation exposure, and transport of the patient to the interventional or operating suite. In the multiply injured trauma or critically-ill intensive care unit patient, often requiring inotropic and ventilator support, transport to these facilities can be hazardous. In addition, these patients frequently have a combination of neurospinal and long bone injuries, which require skeletal immobilization, thus further complicating transportation. Advancing technology with portable duplex ultrasound and improved deep abdominal duplex imaging has allowed for routine diagnostic evaluation of the IVC, renal veins, and surrounding visceral structures. This degree of accuracy has allowed numerous centers to gain experience with ultrasonic imaging of the IVC and insertion site after a filter has been placed. A logical progression has evolved to the point in which, today, duplex ultrasound can be used to guide the insertion of IVC filters. The following describes, in detail, a technique for the percutaneous placement of an IVC filter at the bedside using only duplex ultrasound guidance. The article also briefly compares and contrasts this technique with an alternate technique using intravascular ultrasound. Vena caval interruption can be safely performed under ultrasound guidance in a monitored, intensive care unit environment. In selected intensive care unit or multiply injured trauma patients, this will reduce the risk, complexity and cost of transport for these critically ill patients. Duplex-guided IVC filter placement also reduces procedural costs compared to an operating room or interventional suite, and eliminates intravenous contrast material exposure.

Is renal revascularization in diabetic patients worthwhile

PURPOSE This retrospective review describes surgical management of atherosclerotic renovascular disease (RVD) in hypertensive adults with diabetes mellitus. METHODS From July 1987 through July 1995, 54 consecutive hypertensive diabetics (mean 213/103 mm Hg; mean medications three drugs) requiring either insulin (16 patients) or oral hypoglycemic therapy (38 patients) had operative repair of atherosclerotic RVD. Renal dysfunction (serum creatinine [SCr] > or = 1.3 mg/dl) was present in 82% of patients (mean SCr 2.4 mg/dl). Associations between blood pressure and renal function response to operation and preoperative parameters were examined. Clinical characteristics, response to operation, and dialysis-free survival were compared with those of 291 nondiabetic patients. RESULTS Four (7.4%) operative deaths occurred. Among 50 survivors blood pressure response was considered cured or improved in 72% and unchanged in 28%. Of 42 patients with renal dysfunction 40% had improved function including three patients removed from dialysis. No preoperative parameter examined demonstrated a significant association with blood pressure or renal function response. During follow-up 10 additional patient deaths occurred, and eight patients progressed to dialysis dependence. Time to death or dialysis was associated with preoperative estimates of glomerular filtration (p = 0.03) and the change in estimates of glomerular filtration after operation (p = 0.01). Compared with 291 nondiabetics, the diabetic group had no statistical difference in improved function response (40% vs 51%, p = 0.21); however, diabetics had a significantly lower rate of beneficial blood pressure response (72% vs 89%, p = 0.01) and an increased risk of dialysis or death during follow-up (p = 0.02). By multivariate analysis independent predictors of time to death or dialysis included the presence of diabetes mellitus, patient age, history of congestive heart failure, and increased serum creatinine. CONCLUSIONS Most of the selected diabetic patients had a beneficial blood pressure response after undergoing operative repair of atherosclerotic RVD, albeit at a lower rate compared with nondiabetics. In diabetics poor renal function before and after operation was associated with progression to dialysis and death. Improved renal function after operation was associated with improved survival; however, function response to renal revascularization was difficult to predict.

Femorofemoral bypass for aortofemoral graft limb occlusion: A ten-year experience

PURPOSE Aortofemoral bypass (AFB) is a durable reconstruction; however, graft limb occlusion occurs in 10% to 20% of patients and results in limb ischemia. Treatment of AFB limb occlusion has been debated, but many recommended femorofemoral bypass (FFB). FFB grafts have had excellent patency rates. The durability of FFB specifically for AFB limb occlusion has not been reported. This study retrospectively examined a 10-year experience with FFB for AFB limb occlusion to determine FFB performance. METHODS Between 1982 and 1992, FFB was performed on occluded AFB limbs in 22 patients (14 men and 8 women). Reoperation was performed for disabling claudication in five cases, but the remaining 17 patients (77%) had critical limb ischemia. FFB originated from the contralateral patent AFB limb in all cases. Distal anastomosis was to the common femoral artery (n = 8) or the profunda femoris (n = 14). FFB graft patency was confirmed by direct Doppler arterial examination over a mean follow-up of 47 months. RESULTS The cumulative life-table primary patency rate of FFB was 54% at 5 years. Reoperative procedures performed in nine cases resulted in a secondary patency rate of 84% at 5 years. The limb salvage rate was also 84% at 5 years, reflecting the impact of successful reoperation. Major amputations (two below-knee, one above-knee) were necessary in only three cases. There were no perioperative deaths after FFB, and the cumulative 5-year survival rate was 77%. CONCLUSION Aortic graft limb occlusion occurs less frequently than failure of infrainguinal grafts making the success of specific reoperative strategies difficult to document reliably. This study suggests that FFB is a safe and durable alternative for AFB limb failure. An aggressive policy of reoperation has resulted in successful extension of FFB graft function and an excellent rate of limb salvage.

Ex vivo repair of renal artery aneurysms

OBJECTIVE Renal artery aneurysms (RAAs) are rare but remain challenging lesions when treatment is required. Endovascular techniques may be useful in selected, more proximal lesions with amenable morphology, but open surgical repair is often required for more distal, anatomically complex hilar RAAs that often have several branches and unfavorable anatomy. This study reviewed a single-center experience with ex vivo repair of 14 of these more complex, distal RAAs. METHODS The records of 14 consecutive patients having ex vivo RAA repair between 1997 and 2013 were retrospectively reviewed. Demographic data, operative details, and blood pressure and renal function status were recorded. Graft patency was observed with renal duplex sonography. RESULTS Fourteen hilar RAAs were repaired in 10 women and 4 men with a mean age of 54 years. Hypertension was present in 12 (86%). Preoperative renal dysfunction was present in two (14%). Aneurysm size averaged 2.9 cm. Six RAAs (43%) were symptomatic with flank or abdominal pain. Ex vivo repair was performed in all cases with use of saphenous vein for renal-renal bypass. No patient had pelvic autotransplantation or concomitant aortic reconstruction. Ex vivo RAA repair was technically successful in 12 cases; two patients required nephrectomy. Two patients with pre-existing renal insufficiency had improvement postoperatively, but hypertension was clinically unchanged in all patients. No patient required postoperative dialysis. Duplex sonography documented continued graft patency in the 12 technically successful cases during a mean follow-up of 19 months. CONCLUSIONS Open ex vivo surgical repair with renal-renal bypass is a successful and durable treatment for complex distal RAAs that require repair. These procedures had low morbidity and mortality and an acceptable rate of renal function preservation. Blood pressure control in these patients did not change significantly after RAA repair.