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Biomedical subjects

D E Strandness

Publications and source records attributed to D E Strandness.

At least 91 records · Page 5Linked to original sources
PubMed1994

The future of carotid surgery: changes and problems to solve.

With the publication of the results of clinical trials and acceptance of the role of carotid endarterectomy for treatment of carotid bifurcation disease, it will be up to the surgeons to set the standards for performance that are consistent with the expected outcome. This is a complex issue that will have to be addressed and monitored continually to ensure that patients obtain the optimal and expected results. It will be incumbent on the surgical community to not only set the standards but also to set up mechanisms to monitor the performance of surgeons involved in this procedure. From a scientific standpoint, a great deal of work needs to be done to identify those changes in the plaque that are responsible for the production of clinical events. At present, the only finding that is predictive of outcome is the degree of narrowing. Whereas it is the high-grade lesions that lead to events, the majority will remain benign and not lead to cerebral ischemia. To carry out such research it will be necessary to develop three-dimensional imaging methods that permit measurement of the fibrous cap and the materials beneath it. Since plaque cap rupture with embolization, and in some cases, thrombosis, are the primary causes of clinical events, it will be necessary to measure the cap thickness in symptom-free as well as symptomatic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriosclerosis↗
PubMed1994

Color-flow duplex scanning in the preoperative assessment of TRAM flap perforators: a report of 32 consecutive patients.

This is a report of the results of preoperative color-flow duplex Doppler scanning in the assessment of TRAM flap perforators in 32 consecutive patients. A total of 190 perforators were detected with peak systolic flow velocities ranging from 8 to 81 cm/s. Perforator locations were tabulated according to their vertical position relative to the umbilicus and their lateral location relative to the abdominal midline. The periumbilical region (zones I to III) contained 80.5 percent of the perforators. Asymmetry between the two sides was detected in the majority of patients when perforator positions were evaluated laterally from the midline. The total flap survival rate within the series was 97.9 percent (46 to 47). The present study proposes that the preoperative color-flow Doppler localization of TRAM flap perforators improves the surgeon's ability to design and elevate the flap in order to capture the dominant vessels and maximize survival. In addition, preoperative knowledge of the number and flow velocity characteristics of the perforators allows for the selection of single- and double-pedicle and free TRAM flaps based on each patient's individual perfusion characteristics.

Abdominal Muscles↗
PubMed1994

Diagnostic approaches for detecting deep vein thrombosis.

Acute deep vein thrombosis remains a disease for which the diagnosis must be confirmed by an objective testing procedure. The current methods in use include continuous-wave Doppler, impedance plethysmography, and ultrasonic duplex scanning. The Doppler and plethysmographic methods are of value for the detection of proximal venous occlusion but do have limitations below the knee and fail to provide specific information concerning the exact location and extent of involvement. Duplex scanning, which has both imaging and flow detection capabilities, can be used from the level of the inferior vena cava to below the knee. When duplex scanning is used, the following variables are used in arriving at a diagnosis: visualization of the thrombus, lack of compressibility of the vein, and the absence of spontaneous and phasic flow from the large veins. When all of these variables are used in the screening process, the sensitivity and specificity will be in the range of 90% to 100%. Most false-positive results occur when the incompressibility variable is attempted for the iliac veins and the superficial femoral vein in the adductor canal. The majority of false negatives will be related to missed thrombi in the small veins of the calf.

Humans↗
PubMed1993

Outcome criteria in patients with peripheral arterial disease.

To adequately evaluate patients with chronic occlusive arterial disease several factors will need to be taken into account and documented. These include associated diseases such as diabetes mellitus. When surgical or endovascular therapy is applied, analysis of outcome must include the symptomatic status of the patient, the anatomic evidence of patency of the procedure and of the proximal and distal disease, the hemodynamic result, limb preservation, and mortality. All of these factors will provide a better global picture of the disease and information on how it can be best treated.

Arm↗
PubMed1993

Carotid artery intraplaque hemorrhage and stenotic velocity.

BACKGROUND AND PURPOSE: One of the proposed mechanisms for sudden expansion of a carotid bifurcation plaque is hemorrhage within the lesion. It has been postulated that the sudden increase in plaque size will acutely reduce blood flow to the ipsilateral hemisphere and induce either a transient ischemic attack or a stroke. In this study, the relation between peak systolic velocity at the site of narrowing and its potential role in the development of intraplaque hemorrhage were investigated. METHODS: Ten patients who had carotid endarterectomy were examined by duplex Doppler sonography before surgery to determine the peak systolic velocity at the site of maximal narrowing. The excised carotid plaques were sectioned at 1-mm intervals and examined for histological evidence of intraplaque hemorrhage. The recorded peak systolic velocities in patients with intraplaque hemorrhage were compared with the velocities in cases in which no hemorrhage was identified. RESULTS: Five of the ten patients had intraplaque hemorrhage. Four of the five patients with intraplaque hemorrhage had a peak systolic velocity of > 420 cm/sec and diastolic velocities of > 160 cm/sec; none of the patients without intraplaque hemorrhage had such high values. CONCLUSIONS: Peak systolic velocity is significantly higher in patients with intraplaque hemorrhage. The specificity and sensitivity of a peak systolic velocity of > 420 cm/sec in predicting intraplaque hemorrhage remains to be determined.

Arteriosclerosis↗
PubMed1993

Transcutaneous ultrasonic imaging in peripheral vascular diseases.

Imaging is an important method for studying vascular disease particularly if combined with pulsed Doppler. The only situations where imaging alone may provide enough information to proceed with therapy is with aneurysmal disease and acute deep vein thrombosis. With these disorders, therapy is dependent on identifying the problem, its location, and extent. When occlusive arterial disease is the problem, the need for therapy will depend on the degree of narrowing. At the present time, transcutaneous ultrasonic imaging alone is not adequate to determine the degree of stenosis. Although there is no doubt that plaques can be seen on B-mode imaging, the extent to which they narrow the artery depends on an assessment of the flow velocity through the site of greatest narrowing. This can be determined by using a pulsed Doppler that permits selective sampling of flow from any point within the visualized arterial segment. While the procedure to be used will vary from one site to another within the arterial system, the basic principles are the same. The amount of velocity increase within a stenosis is related to the extent to which the diameter of the artery is reduced. The use of the duplex scanning method will permit an evaluation of both the arterial and venous systems at all sites accessible to this form of energy.

Aged↗
PubMed1993

Carotid endarterectomy: current status, and effects of clinical trials.

With the interim results of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) now reported, it has been shown that carotid endarterectomy is superior to conventional medical therapy for the treatment of symptomatic patients with > 70% diameter-reducing stenosis. The Veterans' Administration trial in asymptomatic patients with a > 50% diameter-reducing stenosis has shown that endarterectomy is superior to conventional non-operative treatment for the prevention of transient ischemic attacks and strokes when these events are combined. The design, impact and potential shortcomings of these trials are reviewed.

Carotid Artery, Internal↗
PubMed1993

Deep venous insufficiency: the relationship between lysis and subsequent reflux.

PURPOSE: Although venous valvular insufficiency is well recognized as the most important etiologic mechanism in the development of the postthrombotic syndrome, the factors contributing to valve incompetence after deep venous thrombosis remain obscure. METHODS: To establish the relationship between recanalization and valve competence, 113 patients with acute deep venous thrombosis were studied with serial duplex ultrasonography. RESULTS: Median lysis times for segments developing reflux (214 to 474 days) were 2.3 to 7.3 times longer than for corresponding segments not developing reflux (65 to 130 days) for all except the posterior tibial vein. In the posterior tibial vein, median lysis times for those with and without reflux were nearly identical (72 vs 80 days). The median time to onset of reflux was significantly less than the median lysis time in the mid and distal superficial femoral veins and was simultaneous with recanalization in all other segments. CONCLUSIONS: Early recanalization is important in preserving valve integrity for all but the posterior tibial segment. However, the small number of patients with reflux despite early lysis (< 1 month) or without reflux despite relatively late lysis (> 9 to 12 months) suggests that other factors may also contribute to the development of valvular incompetence. These factors may be particularly important in the posterior tibial vein, in which lysis time has little relationship to the ultimate development of reflux.

Adolescent↗
PubMed1993

The role of duplex scanning and arteriography before carotid endarterectomy: a prospective study.

PURPOSE: This study examines the current role of diagnostic tests done before carotid endarterectomy and the need for routine arteriography. METHODS: We prospectively studied vascular surgeons' decision-making over a 29-month period during which 111 carotid arteries in 103 patients were considered for endarterectomy. For each case the surgeon's management plan was recorded after clinical evaluation and review of the duplex scan findings, but before arteriography. This plan was later compared with the patient's ultimate clinical management. RESULTS: Of 111 total cases in this period, 17 were excluded from analysis because arteriography was not done or it was performed before the surgeon's evaluation. Carotid duplex scans were diagnostic in 87 (93%) of the remaining 94 cases. The carotid lesion was incompletely assessed by duplex scanning in seven patients because the disease was not limited to the distal common or proximal internal carotid artery (n = 4); anatomic or pathologic features of the carotid artery interfered with imaging or accurate Doppler assessment (n = 1); or an internal carotid artery occlusion could not be distinguished from a high-grade stenosis (n = 2). When a technically adequate duplex scan showed significant disease of the carotid bifurcation, arteriography contributed information that affected clinical management in only a single case (1%). This patient had a middle cerebral artery occlusion distal to a high-grade carotid bifurcation stenosis. CONCLUSIONS: Clinical assessment and duplex scanning were sufficient for the preoperative evaluation of 93% of the candidates for carotid endarterectomy. Clinical circumstances or atypical duplex scan findings can be used to identify the minority of patients for whom arteriography is necessary. On the basis of this experience, we have developed practical guidelines for the selective use of arteriography before carotid endarterectomy.

Adult↗
PubMed1992

Pattern and distribution of thrombi in acute venous thrombosis.

The location and extent of thrombosis in the deep venous system will determine immediate and long-term outcome. During the past 3 years, we have studied by duplex scanning 833 patients with suspected deep vein thrombosis. In this group, 209 patients (25%) had a positive study. The findings relative to location and extent of involvement are as follows. (1) The right leg was involved in 35% of patients, the left leg in 48%. Bilateral involvement was noted in 17%. (2) The veins most frequently affected by deep vein thrombosis were as follows: superficial femoral in 74%, popliteal in 73%, common femoral in 58%, posterior tibial in 40%, deep femoral in 29%, greater saphenous in 19%, and the inferior vena cava in 2%; multisegment involvement was common. (3) Total occlusion was present in 82% of the patients with deep vein thrombosis, and partial occlusion in 18%. (4) Isolated occlusion of single veins was uncommon. (5) The proximal (above-knee) area was involved in 95% of the cases with deep vein thrombosis, and the calf in 40% of the cases. Isolated calf deep vein thrombosis was found in 6% of the cases with right leg involvement and in 3% for the left. (6) Total leg involvement (iliocaval, femoropopliteal, and calf) occurred in 10% of the patients. Our data confirm the fallibility of the clinical diagnosis of deep vein thrombosis. The frequent involvement of both limbs stresses the importance of not examining just the symptomatic limb. Proximal venous thrombosis (popliteal to inferior vena cava) is much more common than isolated calf vein thrombosis as a cause for symptoms and the referral for study.

Adolescent↗
PubMed1992

Vector Doppler: accurate measurement of blood velocity in two dimensions.

An ultrasound Doppler system capable of determining both the magnitude and direction of complex blood velocities has been developed and demonstrated. This system uses a single transmitter and two receivers to resolve orthogonal velocity vector components. The system has been tested on a moving string phantom and on a carotid artery. The method may improve the detection of early vascular diseases and improve the accuracy of volumetric blood flow measurements in peripheral arteries.

Blood Flow Velocity↗