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Biomedical subjects

D E Strandness

Publications and source records attributed to D E Strandness.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Color Doppler characteristics in normal lower extremity arteries.

The purpose of this study was to determine the normal characteristics of the lower extremity arterial system as seen with color Doppler. A total of 420 arterial segments from the level of the proximal abdominal aorta to the distal tibial and peroneal vessels were examined with a color ultrasound scanner in 10 normal volunteers. Each arterial segment was examined for the presence of triphasic flow, wall irregularities, calcification, bruits, collaterals, and post-stenotic flow patterns. Standard duplex spectral waveform data were also obtained at each site. As expected, triphasic flow was present and detected by color Doppler in the majority of arterial segments. Color patterns suggesting the presence of bruits, collaterals, or post-stenotic flow were absent in all cases.

Adult↗
PubMed1992

A preliminary study of the role of duplex scanning in defining the adequacy of treatment of patients with renal artery fibromuscular dysplasia.

Renal artery fibromuscular dysplasia is a well-known cause of hypertension whose presence is confirmed by its typical arteriographic appearance. The functional significance of these lesions is often difficult to determine, particularly when both renal arteries are involved. Duplex scanning has been shown to be accurate for the detection of renal artery stenosis and estimation of the degree of narrowing. To test whether duplex scanning results after intervention correlate with clinical outcome, we reviewed the studies on nine patients with renal artery fibromuscular dysplasia who had been treated by either angioplasty or surgery. A total of 18 arteries were treated. Fourteen of the 18 treatments were successful as measured by a reduction in blood pressure and antihypertensive drugs. In four instances treatment was unsuccessful. For those patients who had clinical improvement, the hemodynamic parameters from the renal artery also improved. In the patients for whom treatment failed, the velocities recorded from the site of narrowing did not improve after intervention. Thus it appears that duplex scanning along with the clinical results may be used to document the basis for failing to improve after treatment be it angioplasty or operation.

Adult↗
PubMed1992

Flow separation in the carotid bulb: prognostic significance.

It has been previously shown that boundary layer or flow separation occurring in the carotid bulb and detected by duplex scanning denotes minimal or no carotid atherosclerotic disease as demonstrated by angiography and reliably predicts aetiology other than carotid artery disease in symptomatic patients. To evaluate outcome at long-term follow-up we prospectively studied 94 patients (48 males, 46 females) who demonstrated bilateral flow separation. Mean age was 61.2 years (27 to 86 years). Mean follow-up was 57 months (5 to 113 months). There was one death during follow-up at 69 months. It was stroke related. Using age and sex specific death rates for the general population 14.3 deaths would be expected for the same average period. By life table analysis, survival was 98.7% at five years compared to a general population expected 5 year survival of 85.9%. There were no strokes at 5 years of follow-up. (Age and sex specific stroke-free survival for Rochester, MN 1970-1974 is 98% at 5 years). TIA-free survival was 99% at one year (n = 87) and 96% at five years (n = 46). It is concluded that the presence of boundary layer separation in the carotid bulb not only indicates absent or minimal atherosclerotic disease, but is predictive of a favourable long-term outcome with respect to mortality and neurological events.

Age Factors↗
PubMed1992

Color Doppler imaging of infrainguinal arterial occlusive disease.

Few reports in the literature validate the use of color Doppler imaging (CDI) for the evaluation of lower extremity arterial occlusive disease, particularly in the tibial and peroneal arteries. This prospective, blinded study compares CDI to arteriography to address the following questions: (1) how well does CDI visualize arterial segments, including those below the knee? and (2) can CDI alone accurately classify the degree of occlusive disease? Twenty-nine men undergoing arteriography before a lower extremity arterial reconstructive procedure were studied with a color ultrasound scanner from the level of the inguinal ligament to the ankle. Color images were examined for the presence or absence of triphasic flow, poststenotic turbulence, color bruits, and collateral vessels. Among 636 arterial segments adequately visualized by arteriography, > or = 90% were identified with color Doppler imaging, including the tibial and peroneal arteries. With color criteria only, specificity was > or = 92% for distinguishing < 50% from > = 50% lesions and > or = 93% for differentiating patent from occluded arteries. Sensitivity for detecting an occlusion was > or = 97% in the superficial femoral (SFA) and popliteal arteries and 83% in the tibial vessels. For identifying a > or = 50% stenosis, sensitivity was > or = 85% in the SFA and popliteal arteries but only 79% and 86% in the posterior and anterior tibial arteries, respectively. CDI reliably identifies vessel location from the level of the groin to the ankle. For the detection of occlusions, CDI is an accurate screening tool in the SFA and popliteal arteries but is less accurate in the tibial vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The potential role of thrombolytic therapy in venous thrombosis.

BACKGROUND: Anticoagulant therapy for lower extremity deep-vein thrombosis (DVT) has been shown to reduce mortality from pulmonary embolism, but subsequent morbidity from the postthrombotic syndrome remains high. Thrombolytic therapy produces higher lysis rates of venous thrombi than heparin alone. Some studies suggest a lower incidence of postthrombotic sequelae after early use of streptokinase. These potential benefits are limited to those patients without contraindications for this therapy. METHODS: For the past 3 years we have prospectively studied patients with DVT documented by duplex scanning. The records of these patients were reviewed to determine what proportion of this population would have been candidates for thrombolytic therapy. For this analysis, contraindications to the use of thrombolytic agents included: (1) recent surgery (less than 1 month); (2) recent major trauma; (3) active or recent bleeding; (4) brain disease (cerebrovascular accident, brain tumor, arteriovenous malformation); (5) pregnancy; and (6) bleeding diathesis. Also, patients with prior ipsilateral DVT and those with acute symptoms present for 7 or more days were not considered to be candidates for thrombolytic therapy. RESULTS: A contraindication to thrombolytic therapy was present in 194 (93%) of 209 patients with a diagnosis of DVT, including four patients with a relative contraindication. Two or more contraindications were present in 65 cases (31%). Recent surgery was the most frequent factor precluding therapy, being present in 71 patients. A history of DVT in the affected leg was present in 45 patients. CONCLUSIONS: Only 15 (7%) of 209 patients with DVT exhibited no contraindications for thrombolytic treatment. Only a small fraction of patients with venous thrombosis will be potential candidates for this therapy.

Adult↗
PubMed1992

Valvular reflux after deep vein thrombosis: incidence and time of occurrence.

From December 1986 to December 1990, 268 patients with acute deep vein thrombosis were studied in our laboratory. From this group 107 patients (123 legs with deep vein thrombosis) were placed in our long-term follow-up program. The documentation of valvular reflux and its site was demonstrated by duplex scanning. The duplex studies were done at intervals of 1 and 7 days, 1 month, every 3 months for the first year, and then yearly thereafter. The mean follow-up time for these patients was 341 days. In addition, reflux was evaluated in 502 patients with negative duplex study results and no previous history of deep vein thrombosis or chronic venous insufficiency. In the patients with acute deep vein thrombosis, valvular incompetence was noted in 17 limbs (14%) at the time of the initial study. Reflux was absent in 106 limbs (86%). In this last group reflux developed in 17% of the limbs by day 7. By the end of the first month, 37% demonstrated reflux. By the end of the first year, more than two thirds of the involved limbs had developed valvular incompetence. The distribution of reflux at the end of the first year of follow-up was the following: (1) popliteal vein, 58%; (2) superficial femoral vein, 37%; (3) greater saphenous vein, 25%; and (4) posterior tibial vein, 18%. Reflux seems to be more frequent in the segments previously affected with deep vein thrombosis. Among cases where segments were initially affected with thrombi, after 1 year the incidence of reflux was 53%, 44%, 59%, and 33% for the common femoral vein, superficial femoral, popliteal vein, and posterior tibial vein, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Clinical significance of retrograde flow in the vertebral artery.

Although retrograde vertebral artery flow was described over 100 years ago, its relationship to symptoms remains unclear. We documented 43 patients who were found by duplex scanning to have reverse flow in the vertebral artery. Of this group, seven patients (16%) were found to have symptoms described as typical for the "subclavian steal" syndrome. Nearly one-third were asymptomatic. Of the remaining patients, 13 (30%) presented with nonhemispheric symptoms while nine (21%) had hemispheric symptoms. Nine patients had "to and fro" flow in the vertebral artery. This variant was not found in subclavian steal patients but correlated with nonhemispheric symptoms. During follow-up (mean: 19 months) none of the asymptomatic patients became symptomatic, and there were no strokes or stroke-related deaths. Surgical procedures which restored antegrade vertebral artery flow did not necessarily improve symptoms of posterior circulation ischemia. In some patients improvement in posterior circulation symptoms was noted following carotid endarterectomy. It is concluded that retrograde flow in the vertebral artery is, per se, a benign entity. Accurate selection of surgical candidates remains imprecise. It will require not only identification of vertebrobasilar disease but as yet undefined tests to assure symptoms are due to these stenoses.

Follow-Up Studies↗
PubMed1991

Integrating research activities, practice changes, and monitoring and evaluation: a model for academic health centers.

A study undertaken by the Joint Commission in 1986 proposed that some research activities at academic health centers (AHCs) be used to fulfill monitoring and evaluation requirements. This paper presents a framework for such use of research activities. To fulfill the monitoring and evaluation standards, AHCs and their medical staff departments must conduct planned and systematic quality assurance activities, and research and subsequent practice changes must be documented. In addition, particular research activities should correspond to the ten steps of the Joint Commission model of the monitoring and evaluation process. It is critical that research result in specific actions to improve care, along with follow-up monitoring and, when necessary, follow-up action.

Academic Medical Centers↗
PubMed1991

The effects of oral nifedipine on hepatic blood flow in humans.

Duplex ultrasonography was used to measure changes in hepatic blood flow in 13 healthy volunteers after they received single doses of 10 mg oral nifedipine and placebo. Blood flow was measured in the hepatic artery and branches of the portal and hepatic veins at baseline and 0.3, 0.6, 1, 1.5, 2, 3, 4, and 5 hours after drug administration. Cardiac output was also measured at baseline and 1, 2, and 3 hours after dosing. Blood flow initially increased in all three vessels 0.6 hour after administration of nifedipine (29%, 56%, and 31% in the hepatic artery, hepatic vein, and portal vein, respectively) compared with placebo. Flow rapidly returned to baseline in the hepatic artery and hepatic vein, whereas it appeared to remain elevated through 3 hours in the portal vein. Nifedipine administration resulted in an increase in cardiac output of 26%, 22%, and 14% above placebo at 1, 2, and 3 hours, respectively. No significant differences were detected in the systolic, diastolic, or mean arterial blood pressures after nifedipine or placebo. This study demonstrates that nifedipine increases hepatic blood flow in a transient nature and systemic hemodynamic parameters do not necessarily reflect specific organ responses. The nifedipine-induced change in blood flow should be considered when nifedipine is coadministered with high-clearance drugs, because systemic availability may be increased.

Administration, Oral↗
PubMed1991

Disposition of drugs in cystic fibrosis. II. Hepatic blood flow.

To determine whether the increased clearance of high extraction-ratio drugs in cystic fibrosis is caused by an increase in hepatic blood flow, the blood flow in main branches of the hepatic vein and portal vein was measured by use of noninvasive duplex ultrasound scanning in 10 adult subjects with cystic fibrosis and in 10 healthy age-, gender-, and height-matched control subjects. No statistically significant differences between subjects with cystic fibrosis and control subjects were detected in either the hepatic vein (217 +/- 103 ml/min for subjects with cystic fibrosis versus 211 +/- 135 ml/min for control subjects) or the portal vein (205 +/- 114 ml/min for subjects with cystic fibrosis versus 190 +/- 101 ml/min for control subjects) blood flows. These data indicate that a large (greater than or equal to 100%) increase in the clearance of high extraction-ratio drugs in patients with cystic fibrosis is unlikely to be primarily caused by an increase in hepatic blood flow. It is probable that alternative mechanisms such as enhanced secretory or metabolic pathways account in large part for increases in clearance of high extraction-ratio drugs.

Adolescent↗
PubMed1991

Role of duplex scanning for the detection of atherosclerotic renal artery disease.

To assess the accuracy of renal artery duplex scanning for the purpose of diagnosing atherosclerotic renal artery stenosis, we compared the findings of renal arteriograms to the results of duplex scanning in 41 patients. Using an increase of renal artery peak systolic flow velocity of greater than 180 cm/sec, duplex scanning was able to discriminate normal from diseased renal arteries with a sensitivity of 95% and a specificity of 90%. Using the principle that blood flow velocity across a stenosis is roughly proportional to the degree of stenosis, it appeared that a ratio of the peak velocity in the renal artery to the aorta (RAR) of greater 3.5 predicted a greater than 60% diameter reduction of that renal artery, which is felt to be a significant stenosis. Forty-eight vessels were classified as having a greater than 60% diameter reduction by arteriography. Using the RAR of greater than 3.5, duplex scanning agreed in 44 renal arteries (sensitivity 92%). In the 26 renal arteries where arteriography showed a less than 60% diameter reduction, duplex scanning agreed in 16 vessels and correctly detected a focal narrowing in nine of the remaining ten vessels. Ten of 11 occluded renal arteries were correctly identified by duplex scanning. Duplex scanning determined the location of the renal artery lesion with an accuracy of 95% (kappa 0.74). Since duplex scanning can accurately demonstrate and locate focal renal artery stenosis, we believe it may become an accurate screening test for renovascular hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

The role of duplex scanning in the selection of patients for transluminal angioplasty.

As part of our initial evaluation to determine whether patients with lower extremity ischemia are candidates for intervention, arterial duplex examinations are performed in the noninvasive vascular laboratory. Patients with isolated short stenoses on the duplex examination are referred for transluminal angioplasty. One hundred thirty-four arteriograms were performed for ischemic peripheral vascular disease in 122 patients between July 1987 and March 1990. One hundred ten (82%) of the arteriograms were preceded by a lower extremity arterial duplex evaluation. Fifty cases (45%) were scheduled for transluminal angioplasty based on the findings of the duplex examination. Transluminal angioplasty was performed in 47 of 50 cases (94%). No significant differences in age, sex, or diabetes were found between the patients who were referred for transluminal angioplasty and those who were not. These data demonstrate that duplex scanning of the lower extremities allows the detection of lesions that will be amenable to transluminal angioplasty. We think that duplex scanning should become the standard screening tool for detection of treatable lower extremity lesions.

Angiography↗