Color-flow Duplex Ultrasound Scanning Research Articles

Duplex ultrasound as the sole long-term surveillance method post-endovascular aneurysm repair: A safe alternative for stable aneurysms

Long-term surveillance with computed tomography (CT) after endovascular aneurysm repair (EVAR) increases both cost and risk. The purpose of this study was to evaluate the safety of an alternative follow-up modality with color flow duplex ultrasound scanning (CDU) as the sole method of imaging. In 2003, we initiated a new follow-up (FU) schedule with yearly CDU as the sole imaging method for selected patients. Indications included a residual sac of less than 4 cm, expanded later to stable sac size for more than 2 years. A stable type II endoleak was not a contraindication. CT scans were obtained selectively-based on suspicious findings of a new endoleak or enlarging sac on CDU. The records of all patients with at least 1 year FU under this schedule were reviewed. One hundred eighty-four patients were followed with CDU only for 1 to 4 years for a mean of 24 +/- 13 months. The new schedule was initiated at a mean of 34 +/- 24 months after EVAR (range 1-112 months). Twenty-three patients had previous endoleaks that had resolved spontaneously or had been treated. During CDU FU, three new endoleaks were detected, one with sac enlargement. All prompted CT evaluation: one type II endoleak with stable sac size could not be identified on CT 3 months later, and two distal type I endoleaks that required limb extension. All three had a prior Ancure endograft. No ruptures or graft occlusions were noted. One abdominal aortic aneurysm (AAA) related death followed graft explantation for infection. There were two additional deaths from malignancy and two from cardiac causes. After the FU switch, freedom from endoleaks was 96%, and from secondary interventions 95% at 48 months by life table method. Mean AAA diameter at baseline was 54 +/- 8 mm and decreased to 40 +/- 11 mm before the switch to CDU only FU. At last FU mean aneurysm diameter was 39 +/- 11 mm. When the current switch criteria were applied to a consecutive series of 200 EVAR patients, 97% would have been eligible for CDU only surveillance by 3 years postoperatively. CDU only surveillance post-EVAR is safe and can be initiated early after treatment in patients with shrinking or stable aneurysms. This policy should result in cost savings advantage and avoid the complications associated with CT.

Endoscopic subfascial perforator vein surgery for patients with severe, chronic venous insufficiency.

Before 1985, surgery on incompetent perforator veins in patients with severe, chronic, venous insufficiency and venous ulcerations was generally performed utilizing long skin incisions through diseased skin and subcutaneous tissues. Known as "the Linton operation," wound infections and poor healing complicated this procedure. In 1985 G. Hauer demonstrated a new surgical technique for identifying and ligating incompetent perforator veins using an endoscopic approach in the limbs' subfascial space. This seminal contribution marked the advent of subfascial endoscopic perforator surgery (SEPS). From 1996 to 2003 our group prospectively collected data on 86 patients with chronic venous insufficiency (CVI) who underwent a SEPS procedure. Preoperative assessment consisted of color-flow duplex ultrasound scanning and ascending and descending phlebography. The patient's ages ranged from 42 to 82 years (mean 60). A total of 98 limbs underwent the SEPS procedure from the cohort group of 86 patients. The CHEAP classification of the limb disease was used: 45 limbs were classified as group C5, 53 limbs group C6. Ninety-eight SEPS procedures were performed without significant morbidity on 86 patients. Of the 53 limbs in class C6, 41 had ulcer healing within 12 weeks. The remaining 12 limbs in class C6 had ulcer healing within 6 months. In this latter group, 9 had ulcers greater than 4 cm in widest diameter. These patients underwent a split-thickness skin graft at the time the SEPS procedure was performed. The grafts have remained intact after 2 years in this cohort group. The results of this study demonstrate that the SEPS procedure incorporated into the overall treatment plan for patients with CVI produces excellent healing with minimal postoperative complications. The study also underscores the important role incompetent perforator veins have in the formation of venous ulcers.

Preoperative and intraoperative evaluation of diameter-reflux relationship of calf perforating veins in patients with primary varicose vein.

Interruption of incompetent perforating veins (PVs) is important for varicose vein surgery. The purpose of this study was to evaluate the preoperative and intraoperative diameter-reflux relationship of PVs and to evaluate the accuracy of preoperative duplex scanning in patients with varicose vein. Patients with primary varicose veins were retrospectively investigated. Diameters and reflux of PVs were evaluated before surgery with color flow duplex ultrasound scan (US). During operation, the incompetent PVs were defined as those that showed an outward spurt of blood flow from the stump of the PVs. The sensitivity and specificity of US in the detection of reflux of PVs were calculated. Competent versus incompetent vein diameters were compared with the Student t test and one-way analysis of variance. Three hundred twenty-four calf PVs were detected in 304 legs of 175 patients with varicose vein. Diameters of competent and incompetent PVs confirmed with intraoperative finding averaged 2.67 +/- 1.10 mm (n = 28) and 3.28 +/- 1.01 mm (n = 58), respectively, at the upper calf (P =.012), 2.85 +/- 0.85 mm (n = 53) and 3.68 +/- 0.94 mm (n = 137), respectively, at the lower calf (p <.001), and 2.67 +/- 0.99 mm (n = 14) and 3.27 +/- 0.66 mm (n = 22), respectively, at the posterior calf (P =.036). The overall sensitivity of detection of reflux with US was 87.7%, and the specificity was 75.3%. Diameters of true-incompetent PVs and false-incompetent PVs were 3.59 +/- 0.94 mm (n = 199) and 3.31 +/- 0.84 mm (n = 24), respectively (P =.157). Diameters of true-competent PVs and false-competent PVs were 2.61 +/- 0.91 mm (n = 73) and 2.89 +/- 0.82 mm (n = 28), respectively (P =.158). Although the diameter of incompetent PVs was larger than that of competent PVs in both US and intraoperative findings, diameter measurement alone can not completely distinguish competent and incompetent PVs. The sensitivity and specificity of reflux obtained with US showed that the accuracy of preoperative duplex scanning to evaluate PV competency was not sufficient.

Identification and implications of transgraft microleaks after endovascular repair of aortic aneurysms

Purpose: The purpose of this report is to describe an interesting cause of endoleak and detail-specific techniques for identifying small transgraft defects, which we have termed microleaks. Methods: Four patients underwent endovascular repair of abdominal aortic aneurysms with modular nitinol/polyester endoprostheses and were studied after 6 to 30 months. All patients were enrolled in standard follow-up radiographic surveillance protocols. Results: Three of the four abdominal aortic aneurysms continued to expand after endograft repair. Standard computed tomography imaging with precontrast, dynamic contrast, and delayed imaging frequently identifies endoleak, although it fails to precisely identify microleaks as the source. Color flow duplex ultrasound scan was performed on three patients and perigraft “jets,” small areas of color flow adjacent to the endograft, were identified in all. Microleaks were identified in one patient who underwent digital subtraction arteriography with directed efforts to completely opacify the prosthesis lumen and multiple oblique projections. In another patient, contrast arteriography with balloon occlusion of the distal endograft clearly depicted midgraft microleaks that might otherwise be mistaken for graft porosity or cuff junction endoleaks. No microleaks were diagnosed on angiograms when these directed efforts were not performed. Aneurysm exploration before aortic clamping provided conclusive determination of the presence of blood flow through the wall of the endoprosthesis in two patients. Conclusions: Microleaks occur up to 2.5 years after endovascular repair of aortic aneurysms. Although computed tomography demonstrates the presence of an endoleak in these patients, the exact site of origin usually remains obscure. Doppler ultrasound scan and directed arteriography appear to be of greater utility for identifying the presence and location of microleaks. Balloon occlusion arteriography and aneurysm exploration without arterial clamping provide definitive evidence of microleaks. Although the clinical significance of microleaks remains unclear, long-term monitoring of patients is imperative to diagnose and treat these and other modes of endograft failure before they progress to aneurysm rupture. (J Vasc Surg 2001;34:190-7.)

Bedside Insertion of the IVC Filter

Pulmonary embolism (PE) remains a leading cause of death among hospitalized patients, and it is well accepted that fatal PE can be pre- vented by the placement of an inferior vena cava (IVC) filter. The progressive refinement of percutaneous insertion techniques for placement of IVC filters has led to a more widespread use of these devices, particularly in high-risk patients in whom other forms of prevention have been ineffective. Even percu- taneous insertion, though, has required fluoroscopic guidance with the need for patients to be moved to an operating room or interventional suite. The transport of critically ill or multitrauma patients requires numerous ancillary staff, which is costly and may be hazardous. Advances in color-flow duplex ultrasound scanning have allowed routine imaging of the iliac veins, and the IVC and IVC filters can be visualized by duplex scan. This combined with the portability of modern ultrasound equipment allows bedside insertion of an IVC filter using ultrasound guidance alone. When technologically feasible, rapid, accurate placement of an IVC filter can be performed without moving the patient from the critical care environment. This strategy reduces the com- plexity of managing these patients and may also reduce the costs and the over- all risks of the procedure. This discussion reviews the indications, technique, complications, and some early follow-up of duplex ultrasound-guided IVC fil- ter insertion (DGFI).

Endoscopic subfascial surgery for incompetent perforator veins in patients with active venous ulceration.

Previously, subfascial ligation of perforator veins to treat venous ulceration in the lower extremities required long skin incisions through diseased skin and subcutaneous tissue. This was known as "the Linton operation." In 1985, Hauer described an endoscopic technique for ligating incompetent perforator veins; this seminal contribution marked the advent of subfascial endoscopic perforator surgery (SEPS). From 1996 to 1998, we prospectively collected data on 41 patients with chronic venous insufficiency (CVI) who underwent a SEPS procedure at our institution. Preoperative assessment consisted of color-flow duplex ultrasound scanning, as well as ascending and descending phlebography. Some 45 SEPS procedures were performed on the 41 patients. Ages ranged from 42 to 84 years (mean, 60). Active venous ulcers were present in 37 legs; healing occurred within 9 weeks in 33 of them. No new ulcers developed in the follow-up period, a mean of 44 weeks. The results suggest that the SEPS procedure incorporated into the overall treatment plan for patients with CVI produces active healing with a minimum of postoperative complications. The study demonstrates the safety and efficiency of this procedure; it also underscores the important role incompetent perforator veins have in the formation of venous ulcers.

Combination of a clinical risk assessment score and rapid whole blood D-dimer testing in the diagnosis of deep vein thrombosis in symptomatic patients

Purpose: The clinical diagnosis of deep vein thrombosis (DVT) is unreliable in more than 50% of cases, and, in recent years, plasma D-dimer assays have been used to predict the presence of DVT with high sensitivity and negative predictive values. This study investigated the use of a rapid whole blood test that could be performed and interpreted by the bedside in addition to a clinically derived risk assessment score (RAS) to determine whether a practical and cost-effective clinical model could be developed for the diagnosis and exclusion of DVT in symptomatic patients. Methods: Two hundred consecutive patients who were referred to the vascular laboratory with clinically suspected DVT underwent the following procedures: (1) clinical assessment and stratification into low, moderate, or high risk for DVT on the basis of an RAS related to history, symptoms, and physical examination findings; (2) rapid (5-minute) whole blood D-dimer testing with a semi-qualitative agglutination technique on a fingerprick blood sample; and (3) color flow duplex ultrasound scanning with standard criteria for the diagnosis of proximal and calf DVT. Results: Forty-six patients (23%) had acute DVT on duplex ultrasound scanning. Of these cases, 28 (61%) had proximal DVT and 18 (39%) were confined to the calf. A total of 88 patients were classified as low risk, 67 were classified as moderate, and 45 were classified as high risk on the basis of the RAS method. Of the patients who were classified at low risk, 4.5% (4/88) had DVT, as compared with 17.9% (12/67) in the moderate clinical risk group and 66.7% (30/45) in the high risk group. Isolated calf DVT was found in 30% (9/30), 50% (6/12), and 75% (3/4) of the high, moderate, and low risk groups, respectively. The sensitivity (8.7%, 26.1%, 65.2%), specificity (45.5%, 64.3%, 90.3%), positive predictive value (4.5%, 17.9%, 66.7%), and overall accuracy rate (37%, 55.5%, 84.5%) of the low, moderate, and high risk groups, respectively, in the diagnosis of DVT increased significantly with increasing risk score stratification. The sensitivity, specificity, positive and negative predictive value, and overall accuracy of the rapid D-dimer test for all DVT were 91.3%, 81.9%, 60%, 96.9%, and 84%, respectively, with a 100% sensitivity and negative predictive value for proximal DVT. A combination of the RAS and D-dimer identified a low risk group with a negative D-dimer as having less than a 1% likelihood of DVT and a high risk group with positive D-dimer as having a likelihood of more than 90%. Conclusion: A combination of clinical assessment and rapid D-dimer testing provides an effective means of excluding proximal DVT in symptomatic patients. The application of a clinical diagnostic model on the basis of these parameters has the potential for saving a large proportion of unnecessary duplex scans with the associated time and costs. (J Vasc Surg 1999;30:794-804.)

New duplex ultrasound scan criteria for managing symptomatic 50% or greater carotid stenosis

Purpose: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) showed that selected patients benefited from surgery when their carotid artery was 50% or more stenosed. This study assessed the accuracy of color-flow duplex ultrasound scanning (DUS) parameters to detect 50% or greater carotid artery stenosis and to determine the situations in which carotid endarterectomy (CEA) without angiography could be justified. Methods: From March 1, 1995, to December 1, 1995, all patients considered for CEA were studied with DUS and carotid angiography. Results of the two tests were blindly compared. DUS measurements of internal carotid artery (ICA) peak systolic velocity (PSV), end diastolic velocity, and ratio of the ICA to common carotid artery PSV (ICA/CCA) were subjected to receiver operator characteristic curve analysis to determine the most accurate criterion predicting 50% or greater angiographic stenosis. The criterion for identifying patients for CEA without angiography was selected from criteria with a high positive predictive value (PPV) and sensitivity. Results: A total of 188 carotid bifurcations were available for comparison. A PSV (ICA/CCA) of 2 or higher was the most accurate criterion for detection of 50% or greater stenosis, with an accuracy rate of 93% (sensitivity, 96%; specificity, 89%; PPV, 92%). A PSV (ICA/CCA) of 3.6 or higher was the best criterion for identifying candidates for CEA who had not undergone earlier angiography, with PPV, sensitivity, specificity, and accuracy rates of 98%, 77%, 98%, and 86%, respectively. Conclusion: These redefined criteria detect the NASCET-defined threshold level of 50% or greater ICA stenosis, above which CEA results in stroke reduction. A management algorithm based on these criteria should help to minimize both angiography and unnecessary intervention. (J Vasc Surg 1999;29:986-94.)

Saphenous surgery does not correct perforator incompetence in the presence of deep venous reflux

Purpose: To determine which patients require subfascial endoscopic perforator surgery (SEPS) in addition to saphenous surgery to correct pathologic outward flow within incompetent medial calf perforating veins (IPVs). Methods: Sixty-two limbs of 47 patients undergoing sapheno-femoral ligation, stripping of the long saphenous vein in the thigh, and multiple phlebectomies (n = 51), sapheno-popliteal ligation and multiple phlebectomies (n = 10), or both (n = 1) were examined with color flow duplex ultrasound scan immediately before and a median of 14 weeks (range, 6 to 26 weeks) after the operations. Indications for surgery were varicose veins (n = 47, Clinical, Etiologic, Anatomic, Pathophysiologic grades C 2&3), skin changes (n = 5, C 4), and ulceration (n = 10, C 5). Results: Surgery resulted in a significant reduction in the total number of limbs in which IPVs were imaged (40/62 or 65% preoperatively vs 23/62 or 37% postoperatively, P <.01, χ 2 test), a significant reduction in the proportion of perforators imaged that were incompetent (68/130 or 52% preoperatively vs 34/120 or 28% postoperatively, P <.01, χ 2 test), and a reduction in median IPV diameter (4 mm, with a range of 1 to 11 mm preoperatively, vs 3, with a range of 1 to 8 mm postoperatively, P <.01, Mann-Whitney U test). IPVs remained in 8 of 41 (20%) limbs in which main stem reflux was abolished, compared with 15 of 21 (72%) limbs in which superficial or deep reflux remained ( P <.01, χ 2 test). Conclusion: Eradication of main stem saphenous reflux corrects IPV reflux in most cases in which reflux is confined to the superficial system. However, in patients with superficial reflux that persists postoperatively, or when there is coexistent deep venous reflux, saphenous surgery alone fails to correct IPVs reflux. In these circumstances, the only way of reliably correcting pathologic outward flow in medial calf perforating veins is to perform SEPS. (J Vasc Surg 1998;28:834-8.)