The field of thromboembolic disease has undergone a major transformation in the past few years. Although it is now accepted that bedside diagnosis is inadequate, how the disease was treated remained relatively stable until low-molecular-weight heparin appeared on the scene. The appearance of this new drug was paralleled by the studies showing that catheter-directed thrombolytic therapy could be useful in clearing thrombus from the deep venous system and preserve both vein patency and valve function. We are currently in the sorting out mode to determine which patients can be treated at home with low-molecular-weight-heparin, which patients need to be hospitalized, and which patients deserve thrombolytic therapy. It is certain that the field will continue to evolve as new antithrombotic drugs appear, and our approaches to treatment will have to be modified again.

Clinical Pharmacology & Therapeutics (1996) 59, 149–149; doi: 10.1038/sj.clpt.1996.94

PURPOSE:B-mode imaging of a normal arterial wall shows two echo-dense lines separated by an echolucent zone. Immediately after carotid endarterectomy, this double-line pattern is no longer detectable, but it subsequently reappears in some patients. The objective of this study was to test the hypothesis that the postoperative double line is associated with a lower incidence of carotid restenosis. METHODS:Carotid arteries were serially studied with B-mode ultrasound imaging at 2 weeks and 1, 2, 3, 6, 9, 12, 18, and 24 months after carotid endarterectomy. The wall of the common carotid artery 1 to 2 cm distal to the proximal endarterectomized shelf was analyzed for the presence, quality, and thickness of double lines. All hemodynamically significant stenoses (> or = 50% diameter reducing) were documented with standard duplex scanning criteria. RESULTS:Twenty-four carotid arteries in 23 patients were studied for a mean of 14.7 months (range, 3 to 24 months). A double line developed in 21 common carotid arteries (87.5%) at a mean time of 3.2 months (range, 0.5 to 9.0 months) after surgery with a mean thickness of 0.65 mm (SD = 0.17 mm) at the time of initial detection. A single hemodynamically significant stenosis developed in this group. All three of the remaining arteries that did not form the double-line pattern developed hemodynamically significant stenoses. Carotid restenosis was more likely to occur in arteries that did not form double lines (p < 0.05, Fisher's exact test). CONCLUSIONS:The majority of carotid arteries re-form a double line after endarterectomy. These arteries are less likely to develop restenotic lesions caused by myointimal hyperplasia.

Recognizing the considerable excess burden of both cerebrovascular disease and LEAD suffered by individuals with IDDM or NIDDM (1,2), a workshop was convened to 1) provide a current review of the knowledge pertaining to the prevalence, incidence, and risk factor associations of cerebrovascular disease and PVD in diabetes, and 2) review and make recommendations about the methodology for identifying and quantifying LEAD in both clinical and research settings.

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.

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.

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.

In order to accurately describe the role diabetes plays in the pathogenesis of arteriosclerosis and its relationship to clinical practice, one must not only compare diabetics to nondiabetics of similar age and sex but also attempt to identify those factors unique to diabetics. Of the approximately six million Americans with diabetes mellitus, 90% have type-I1 (noninsulin dependent) diabetes. The remaining lo%, the type-I patients, must take insulin for survival. There are clearly profound differences between type-I and type-II diabetics which have a direct bearing both on how we perceive the disease and approach its management. Of all amputations done in America, one-half are done in diabetics for reasons other than trauma. The reasons for such a high incidence of limb loss have been attributed to a variety of factors, which include extensive atherosclerosis, peripheral neuropathy , increased susceptibility to infection, Monckeberg’s medial sclerosis, and microvascular disease. This section will delineate the important factors based on current information. It is important to realize that much more is unknown than known. The one factor that needs to be dispelled is the myth of the role of the microcirculation in the promotion of tissue ischemia and death. The commonly held ideas about a specific diabetic microangiopathy pertains only to the eye, the kidneys, and perhaps the heart. Evidence for the presence of microcirculatory lesions other than a thickening of the capillary basement membrane in the lower limbs of diabetic patients is unconvincing at present.

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.

Disease of the mesenteric circulation can exist in three forms: (1) acute mesenteric occlusion with death of the small bowel; (2) chronic mesenteric angina; and (3) asymptomatic involvement. Acute ischaemia of the small bowel has a dramatic presentation dictating emergency measures for survival of the small bowel and the patient as well. Patients who are best subjects for non-invasive studies are those with symptoms suggestive of chronic mesenteric ischaemia.

The management of internal carotid artery disease contralateral to endarterectomy is highly controversial. At our institution we have adopted an approach by which patients are followed with serial duplex scanning after unilateral carotid endarterectomy. Surgery on the contralateral carotid artery is recommended for patients who exhibit ischemic neurologic symptoms or develop an 80% to 99% carotid stenosis. This strategy is based on previous reports that have documented an increased incidence of strokes in these two groups of patients. As a result, 40 patients among a study population of 200 underwent carotid endarterectomy on the originally unoperated side. The current study reviews the natural history of the patients who were followed without or before operation of the contralateral carotid artery in an attempt to identify other cohorts at increased risk for stroke. Patients were followed for up to 126 months after unilateral carotid endarterectomy (mean, 54 months). Six patients were lost to follow-up (3.0%). By life-table analysis the estimated mean annual rate of progression to ≥50% diameter reduction was 3.9% and 1.2% for progression to ≥80% stenosis. Only two patients went on to occlusion during follow-up. Neurologic events referable to the contralateral carotid distribution were infrequent. The estimated mean annual rate was 2.9% for transient ischemic attacks and less than 0.8% for strokes. Case history review of the six patients who had strokes during follow-up suggested that only one patient may have benefited from carotid endarterectomy. Conservative management with serial duplex scanning of the unoperated, contralateral carotid artery appears appropriate. Endarterectomy should be reserved until symptoms develop or until an 80% to 99% contralateral carotid stenosis is detected. A more aggressive operative strategy is not supported by our findings. (J VASC SURG 1990;11:244-51.)

This preliminary study was undertaken to determine if surgeons would choose different intervention for lower extremity occlusive disease when given basic clinical information and data from either a duplex scan or arteriogram. Information on degree of stenosis from duplex scans and arteriograms of 29 patients was indicated on an anatomical line drawing along with the ankle blood pressures and a brief clinical description. Based on these data sheets, six vascular surgeons chose a clinical plan in a blinded fashion for each patient. Each plan was placed into one of eight possible categories for comparison using the kappa statistic.Intraobserver agreement between surgeons' decisions based on duplex scanning versus those based on arteriography was very good (mean kappa .70 with exact agreement in 76%).Interobserver agreement between different surgeons' decisions based on the same studies was significantly less (mean kappa 0.56, p<.05). Significant disparity in clinical approach occurred in 43% of the patients with nearly identical duplex scan and arteriogram reports, suggesting that much of the discrepancy lies in the clinical decision-making process. Clinical decisions made using duplex scans are very similar to those made using arteriograms. This technique can limit the need for arteriography in assessing patients with lower extremity arterial occlusive disease.

This chapter contains sections titled: Ultrasound basics Carotid and vertebral-artery duplex scanning Peripheral artery duplex scanning Visceral arteries Venous disease Chronic venous insufficiency Selected miscellaneous examinations References

Little has been recorded in the anesthesia literature concerning the changes in the electroencephalogram (EEG) that may occur during carotid endarterectomy many minutes after shunt placement and restoration of flow and that may be attributed to "delayed" shunt occlusion or cerebral emboli. We describe a patient in whom EEG changes indicative of cerebral ischemia occurred at the time of carotid clamping. The changes resolved promptly after placement of a carotid shunt but recurred 11 minutes later. Because of the EEG changes, the carotid shunt was evaluated and found to have become occluded. EEG monitoring was crucial to the detection of shunt occlusion in the absence of other systemic changes or surgical difficulties. The rapidity and magnitude of the changes in the EEG suggest that, if the occlusion had not been discovered and the patency of the shunt restored, the patient would have been at increased risk for neurologic injury.

Of the wide variety of noninvasive carotid examinations available, Duplex scanning offers the best combination of accuracy and detection of all clinically important lesions. Extensive technician training is required and the initial cost of the instrument is high, but the versatility of the method and a low cost per patient makes Duplex scanning cost effective. When high initial capital investments are not possible the use of pressure OPG or simple continuous-wave Doppler devices are satisfactory alternatives to screen for high grade lesions.