Relationship of extracranial carotid occlusive disease and central retinal artery occlusion

Central retinal artery occlusion usually results in blindness. The association between central retinal artery occlusion and extracranial carotid disease has not been clearly delineated. We reviewed the case reports of 62 patients with central retinal artery occlusion, 25 of whom underwent carotid angiography as part of the diagnostic evaluation. Fourteen of the 25 (56 percent) were found to have ipsilateral extracranial carotid disease. These patients did not generally have carotid bruits and had normal noninvasive carotid tests. Ten patients underwent ipsilateral carotid endarterectomy; these patients had either embologenic ulcerated plaque or tight stenosis of the carotid artery. There were 11 patients who showed no abnormalities on angiography. Thirteen patients who did not undergo angiography showed clinical evidence of etiologic factors, including vasculitis, an embolism of cardiac origin, and trauma. The remaining 24 patients had no diagnostic workup. Follow-up data were available in six of those patients who underwent carotid endarterectomy for a mean of 34 months; no strokes were reported. In conclusion, over half of patients with central retinal artery occlusion who undergo carotid angiography will have a carotid lesion on the ipsilateral side. This suggests that central retinal artery occlusion is a significant marker for extracranial carotid disease and should be an indication for complete carotid evaluation.     

The limitations of diagnosis of carotid occlusion by Doppler ultrasound.

Duplex scanning has been advocated as an acceptable alternative to angiography in the preoperative evaluation of carotid artery stenosis. To evaluate the accuracy of carotid Doppler in differentiating severe carotid stenosis from occlusion, we compared the results of angiography with duplex scanning in 124 carotid arteries (62 patients) and with continuous-wave Doppler in 662 carotid arteries (331 patients). The specificity was 95-99%, sensitivity was 86-96%, and accuracy was 95-98%. Duplex scanning wrongly identified occlusion in four arteries and failed to detect occlusion in one artery. In making decisions prior to carotid endarterectomy, even infrequent errors are unacceptable. We recommend angiography of all surgical candidates with apparent severe stenosis when the internal carotid artery cannot be clearly identified on duplex, or to distinguish apparent occlusion from undetectably low blood flow.     

The association of central retinal artery occlusion and extracranial carotid artery disease.

To determine the incidence of associated carotid artery disease and the effect of carotid endarterectomy on subsequent neurologic sequelae, a retrospective study of 66 patients with central retinal artery occlusion (CRAO) was undertaken. Ipsilateral extracranial carotid artery disease was present in 23 of 33 patients (70%) who had carotid arteriography. Sixteen patients had carotid endarterectomy following their CRAO (Group I) and 50 did not (Group II). Seven of the 40 patients available for follow-up in Group II had a subsequent stroke (mean follow-up: 54 months). Of the seven Group II patients shown to have associated carotid disease (Group IIs), three (43%) had a subsequent stroke during follow-up (mean: 28.3 months) compared to zero in Group I (p = 0.033; mean follow-up: 18.7 months). Because of the strong association between CRAO and ipsilateral carotid artery disease and because of the significantly higher incidence of subsequent ipsilateral stroke in CRAO patients with carotid disease who did not undergo endarterectomy, thorough evaluation of the carotid arteries followed by carotid endarterectomy, if indicated, is warranted in CRAO patients who have no other obvious etiology for the occlusion.     

Retinal artery emboli. Indications for angiography and carotid endarterectomy.

Six patients with ocular symptoms were referred by the Eye Service to the Vascular Service because of the presence of cholesterol emboli on fundoscopic examination of the retinal arteries. None of the six patients had classic intermittent retinal or cerebral ischemic attacks. Four-vessel aortic arch arteriogram was suggested and significant ipsilateral carotid disease was found in all patients. Four patients underwent carotid endarterectomy, with removal of ulcerated plaques from the carotid bifurcation. Two patients had total occlusion of the ipsilateral internal carotid artery and therefore were not operative candidates. The presence of retinal cholesterol emboli is an indication for extracranial arteriography. When ipsilateral ulcerative disease is found, carotid endarterectomy is indicated regardless of the symptoms.     

Stenosis of one carotid artery with occlusion of the contralateral carotid

Summary 23 patients with unilateral internal carotid artery stenosis (>70%) and contralateral internal carotid artery occlusion in the neck are reported. The symptoms are referable to the side of the occlusion in 13 cases (57%), to the side of stenosis in 7 cases (30%) and non-localizing in 3 cases (13%). All 23 patients had a carotid endarterectomy performed on the side of the stenotic lesion. There was no operative mortality. Late neurological symptomatology after surgery was referable to the side of stenosis in 13% and to the side of occlusion in 9%. The authors consider that, in cases of significant stenosis (greater than 70%) of an internal carotid artery with a contralateral occlusion, preference should always be given to endarterectomy of the stenotic side, reserving extra-intracranial by-pass of the occluded side for patients who remain symptomatic after endarterectomy of the stenotic side.     

A four-year experience with preoperative noninvasive carotid evaluation of two thousand twenty-six patients undergoing cardiac surgery

From January 1979 through December 1982, 2026 patients scheduled to undergo open heart surgery were evaluated by a preoperative battery of noninvasive carotid tests including phonoangiography, oculopneumoplethysmography, pulse-timing oculoplethysmography, periorbital Doppler examination, and during the last 12 months, continuous-wave Doppler ultrasonography with spectral analysis. The incidence of hemispheric neurologic deficit following cardiac surgery in the 47 patients with carotid disease was 14.9%; the incidence in patients with no carotid disease was 1.9% (p less than 0.001). Fourteen of the 47 patients were not candidates for carotid surgery because of unilateral occlusion in 13 and bilateral occlusion in one. Three of the 14 (21.4%) had intraoperative strokes on the appropriate side. Thirty-three of the 47 had operable carotid disease. Four with unilateral stenosis had no carotid surgery; one had a postoperative deficit on the side referable to the nonstenotic artery. Eighteen with unilateral stenosis underwent simultaneous cardiac and carotid surgery; one (5.6%) had a transient deficit. Seven patients with bilateral stenosis underwent cardiac and unilateral carotid surgery; no deficits occurred. Four patients with unilateral stenosis and contralateral occlusion underwent combined surgery; one had a transient ischemic attack and one a fatal stroke, both referable to the hemisphere ipsilateral to the occlusion. It appears that the presence of carotid disease increased the risk of stroke during heart surgery. Proof that carotid endarterectomy lowers this risk awaits a prospective randomized trial.     

The Fate of a Patent Carotid Artery Contralateral to an Occlusion

The finding of carotid stenosis contralateral to a carotid occlusion is becoming more frequent. While the neurologic outcomes in this patient population have been described, the rate of disease progression measured by duplex examination and the eventual need for carotid endarterectomy has not been described. In this study, a computerized database of carotid duplex examinations was reviewed and clinical data were obtained from clinic records. From 9124 studies 117 patients were identified. Thirty patients had previous carotid surgery on the patent side and were excluded. Of 87 patients 33 required carotid endarterectomy on the patent side. The rate of disease progression and/or the performance of a carotid endarterectomy by life-table analysis was 85.9% over 8 years. There were 10 neurologic events during the follow-up period. Patients with carotid stenosis and contralateral occlusion are at significant risk for disease progression. Follow-up should be more frequent and of longer duration in this patient population. A significant number of patients with carotid artery occlusion will require a carotid endarterectomy of the patent contralateral carotid.     

Effect of carotid endarterectomy on chronic ocular ischemic syndrome due to internal carotid artery stenosis

OBJECTIVE: We evaluated the effect of carotid endarterectomy on chronic ocular ischemic syndrome due to internal carotid artery stenosis by use of data obtained from ophthalmic artery color Doppler flow imaging. METHODS: We examined 11 patients with ocular ischemic syndrome due to internal carotid artery stenosis (>70% stenosis) who were being treated by carotid endarterectomy. Ophthalmic artery color Doppler flow imaging indicated ophthalmic artery flow direction and peak systolic flow velocity and was performed before and at 1 week, 1 month, and 3 months after surgery. RESULTS: We assessed the ophthalmic arteries of 11 patients via color Doppler flow imaging. Before undergoing carotid endarterectomy, five patients showed reversed ophthalmic artery flow. In the other six patients who experienced antegrade ophthalmic artery flow, the average peak systolic flow velocity was 0.09 +/- 0.05 m/s (mean +/- standard deviation). Preoperative reversed flow resolved in each patient 1 week after undergoing surgery. All patients showed antegrade ophthalmic artery flow. The average peak systolic flow velocity in the patients who had preoperative antegrade flow rose significantly, to 0.21 +/- 0.14 m/s (P < 0.05). There was no significant change as compared with findings at 1 week after surgery. During the follow-up period (mean, 32.4 mo), no patients complained of recurrent visual symptoms. At the end of the study period, visual acuity had improved in five patients and had not worsened in the other six patients. CONCLUSION: Carotid endarterectomy was effective for improving or preventing the progress of chronic ocular ischemia caused by internal carotid artery stenosis.     

Management of the external carotid artery during routine carotid endarterectomy.

This study analyzes the results of carotid endarterectomy with a uniform technique of external carotid artery management. Aggressive blind instrument and eversion endarterectomy of the distal external carotid and its branches above the superior thyroid artery was performed during 211 standard carotid endarterectomies. This technique allows isolated external carotid artery repair if necessary after re-establishing carotid blood flow. Of these, 196 (92.9%) had normal intraoperative continuous wave Doppler ultrasonography in the external carotid. The 15 (7.1%) abnormal external carotid arteries underwent isolated completion endarterectomy with or without patch reconstruction followed by a normal Doppler study. All 15 had normal external carotid artery duplex ultrasonography 3 to 6 months after endarterectomy. However, 2 of the 196 (1.04%) intraoperative ultrasound normal external carotids had significant residual or recurrent stenosis (no occlusions) 3 to 6 months after endarterectomy for an early external carotid residual or restenosis rate of 0.95% (2/211). This was significantly less (p less than 0.05) than the 5.2% (11/211) 3- to 6-month incidence of residual or recurrent external carotid stenosis (6) and occlusion (5) in 211 carotid endarterectomies in which the external carotid artery was managed in an arbitrary manner. This study supports aggressive eversion endarterectomy of the external carotid artery during standard carotid endarterectomy with isolated repair when indicated.     

Fate of the carotid artery contralateral to endarterectomy

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 greater than or equal to 50% diameter reduction was 3.9% and 1.2% for progression to greater than or equal 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.(ABSTRACT TRUNCATED AT 250 WORDS)     

Carotid endarterectomy contralateral to an occluded carotid artery: perioperative risk and late results

To define better the short-term risk and long-term benefit of carotid endarterectomy opposite an occluded carotid artery, we reviewed our experience since 1961. Angiographic data are available for 598 of 670 (89.3%) patients in our carotid registry. In 63 (10.5%) patients the internal or common carotid artery on the side opposite the endarterectomy was occluded. All operations were carried out under general anesthesia with selective shunting based on electroencephalographic criteria. Shunting was required in 29 of 63 (46.0%) patients with contralateral occlusion and 72 of 535 (13.5%) control subjects (p less than 0.0001). Perioperative strokes occurred in 3 of 63 (4.8%) patients with contralateral occlusion and 14 of 535 control subjects (2.6%) (p = 0.23). Perioperative death occurred in 0 of 63 patients with contralateral occlusion and 6 of 535 (1.1%) control subjects (p = 0.40). Life-table cumulative stroke-free rates at 1, 5, and 10 years were 95.2%, 91.0%, and 76.2% in the group with contralateral occlusion and 96.0%, 89.4%, and 84.1% in control subjects (p = 0.25). Life-table cumulative survival rates at 1, 5, and 10 years were 93.1%, 80.8%, and 75.4% in the group with contralateral occlusion and 94.8%, 77.0%, and 57.9% in control subjects (p = 0.58). Carotid endarterectomy contralateral to an occluded carotid artery may be carried out with acceptable risk and late stroke-free and survival rates comparable to those seen in other patients who have undergone carotid endarterectomy.     

Association of carotid artery atheromatous plaque types with cerebral perfusion

Background: In an attempt to define the association of internal carotid artery atheromatous plaque morphology with potential cerebral ischaemia, we have investigated the relationship of different carotid plaque types with defects in cerebral perfusion. Methods: In 130 patients requiring surgical correction of internal carotid artery stenoses greater than 70%, defects in cerebral perfusion due to both haemodynamic insufficiency and intracerebral vessel occlusion were identified using single photon emission computed tomography scans (SPECT). Carotid artery plaques in these patients were classified as homogeneous or heterogeneous based on preoperative Doppler Duplex Scanning and on the macroscopic characteristics of the plaques recorded by the surgeon during carotid endarterectomy, with sub‐classification into potentially embolus‐generating and non‐ embolus‐generating plaques. In individual patients, plaque types were then correlated with the perfusion defects found in the SPECT scans. Results: Of 130 patients, 112 (86%) had cerebral perfusion defects. In 56 asymptomatic patients in the study, 48 (85.7%) had perfusion defects as did 64 (86.5%) of 74 symptomatic patients. Cerebral infarcts were seen in 41 (31.5%). Occlusive infarcts (66%) were twice as frequent as haemodynamic insufficiency infarcts (34%). Eighteen patients with small cerebral infarcts on SPECT scanning gave no medical history of cerebral symptoms. Statistical analysis of the results revealed that there was no statistically identifiable association between carotid plaque type and the generation of cerebral symptoms or infarction. Conclusion: This study found that internal carotid plaque morphology has no statistically significant association with perfusion defects, symptoms or cerebral infarction in patients with significant internal carotid artery stenosis. Also, it is suggested that haemodynamic cerebral infarction may be more common that previously believed (34% of infarcts identified in the study). Further, it is suggested that plaque morphology alone is not an indication for carotid endarterectomy.     

Flow redistribution in the major cerebral arteries after carotid endarterectomy: a study with transcranial Doppler scan

PURPOSE: This open single-center prospective study aimed to determine the redistribution of blood flow within the circle of Willis and through collateral pathways after carotid endarterectomy. Blood flow velocity and flow direction in the major cerebral arteries were determined, both at rest and during CO(2) inhalation. METHODS: Carotid endarterectomy was performed in 148 patients with a 70% or greater diameter stenosis of the internal carotid artery while patients were under general anesthesia. Arteriotomy closure was done with a venous patch. Selective shunting was performed with an electroencephalogram. Baseline blood flow velocity of the basal cerebral arteries was measured by means of transcranial Doppler sonography preoperatively (within 1 week before surgery) and 3 months postoperatively. At the same times, cerebrovascular reactivity was calculated during CO(2) inhalation insonating both middle cerebral arteries. RESULTS: Baseline blood flow velocity in the ipsilateral middle cerebral artery hardly changed 3 months postoperatively, but there was a considerable redistribution of flow in the circle of Willis. This was characterized by a decrease in contribution from the contralateral hemisphere through the anterior communicating artery, reduced cerebropetal flow rates in the ophthalmic artery, and smaller contribution of the posterior collateral sources. The CO(2) reactivity on the side of surgery increased in all patients. In patients with a contralateral occlusion, CO(2) reactivity increased on both sides. The redistribution of flow was most pronounced in patients who needed intraoperative shunting and in patients with a contralateral internal carotid artery occlusion. CONCLUSION: After carotid endarterectomy, flow redistribution, as expressed by changes in blood flow velocity values, occurs in the circle of Willis. The contribution of collateral sources is diminished, and the CO(2) reactivity increases, both of which reflect improvement of the hemodynamic condition. The most improvement occurs in patients with contralateral occlusion.     

Duplex and transcranial sonography in the preoperative evaluation of cerebrovascular circulation before heart operations

Fifty unselected patients undergoing open heart surgery (OHS) were examined by duplex and transcranial Doppler sonography. Two high degree (greater than 75%) carotid stenosis were found in 70 carotid arteries of 35 patients with coronary artery disease. Fourteen vessels had unmistakable signs of extracranial vascular disease whilst 54 carotid arteries were identified as normal. Two high degree (greater than 75%) carotid stenosis were found in 30 vessels of 15 patients with valvular disease. Seven other vessels had a low grade stenosis or excessive atheroma, whereas 21 were identified as normal. The rate of about 5-10% asymptomatic high grade carotid stenosis in patients undergoing OHS justifies routine noninvasive examination of the cerebral circulation by duplex and transcranial Doppler sonography. Patients with high grade stenosis are offered a follow-up preventive programme against cerebral infarction, which consists of 3 steps: 1. anti-platelet aggregating drugs, 2. periodic control examinations by duplex and transcranial Doppler sonography, and 3. continued evaluation of indication for carotid endarterectomy.     

Operative strategies in patients with symptomatic internal carotid artery occlusion

A 15-year experience with 98 patients who underwent extracranial artery reconstruction for symptomatic internal carotid artery occlusion is reviewed. Thromboendarterectomy of the occluded carotid artery resulted in unacceptably high mortality and morbidity rates, and long-term patency of the internal carotid artery was rarely achieved. Carotid endarterectomy on the side opposite the occlusion proved to be successful in relieving nonlateralizing symptoms of cerebral ischemia, whereas results were less encouraging in patients with focal symptoms in the hemisphere ipsilateral to the occlusion. External carotid artery reconstruction on the side of the occlusion was successful in relieving focal symptoms. Surgical treatment in patients with symptomatic internal carotid artery occlusion should be planned in each patient on the basis of symptoms and anatomic pattern.     

Current management of the patient with internal carotid artery occlusion

Despite the recent controversy concerning surgical therapy of patients with carotid artery disease, rational therapeutic plans can be developed based on available data. The patient who is symptomatic from occlusion of one or both internal carotid arteries is at particularly high risk for development of stroke and can ill-afford indecision. All symptomatic patients, therefore, with any of the extracranial occlusive disease patterns described are potential surgical candidates. Conversely, among the asymptomatic patients with these same patterns of occlusion, only those with internal carotid occlusion and contralateral stenosis should be considered for surgical therapy. Treatment must be individualised and directed at revascularising stenotic (not occluded) internal carotid arteries, or important collateral vessels such as the external carotid artery and in fewer cases the vertebral artery. The asymptomatic patient with unilateral internal carotid artery occlusion and no contralateral lesions should be monitored closely with Duplex scanning for development of a contralateral stenosis. When a stenosis of 80% or greater is encountered, strong consideration should be given to prophylactic endarterectomy in these patients due to their high risk for stroke. Endarterectomy for a 50-60% stenosis may also be reasonable in a single patent internal carotid artery. In the absence of a significant contralateral stenosis, no treatment is necessary. Individuals with internal carotid artery occlusion and symptoms referable to a contralateral carotid stenosis should also be managed with endarterectomy of the stenotic carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Management of internal carotid artery occlusion

Although attempts to restore patency of occluded internal carotid arteries are now rarely made, endarterectomy in the contralateral artery, external carotid endarterectomy and until recently EC/IC bypass have remained surgical options in the management of such patients. Over a four-year period at this institution 104 patients underwent carotid endarterectomy for stenosis. In this group the contralateral carotid was patent (Group A). Fifty-four patients with unilateral carotid artery occlusion underwent contralateral endarterectomy (Group B), 8 underwent ECA/ICA bypass (Group C) and 4 an ECA endarterectomy (Group D). No statistically significant difference was noted in perioperative stroke and death rates for Groups A and B were (1% and 1%) and (3.7% and 1.9%) respectively. One Group C patient died from perioperative stroke (12.5%). For late events the life table adjusted annual rates for stroke and mortality were similar, Group A (stroke 2.1% and death 5%), and Group B (stroke 1.6% and death 5%). In Group C stroke rate was 10% and death 3%. All four patients undergoing ECA endarterectomy were relieved of their symptoms. It is concluded that in patients with internal carotid artery occlusion TEA may be performed with perioperative morbidity and mortality rates comparable to those when the opposite carotid artery is patent. The late outcome for stroke compares favorably with the reported natural history of the disease and outcome for such patients treated medically in the Joint Study of Extracranial Occlusion and EC-IC Bypass Study. External carotid artery endarterectomy appears useful in the treatment of embolic events on the occluded side. ECA/ICA bypass does not appear to confer benefit.     

Re-evaluation of Carotid Duplex for Visual Complaints: Who Really Needs To Be Studied?

Amaurosis fugax (AF), Hollenhorst plaques, central retinal artery occlusion (CRAO), and nonspecific visual symptoms are all reasons for patient referral for carotid artery evaluation. This study reviews the management of patients with visual signs or symptoms based on their clinical presentation, carotid duplex results, follow-up data, and outcome. We performed a retrospective review of all patients presenting to the Vascular Surgery Clinic between June 1996 and December 2001 for carotid duplex scanning because of the indication of a visual disturbance. A total of 3560 carotid duplex examinations were performed during the study period; 98 were performed for a visual complaint or finding. A total of 11.1% of group 1 (Hollenhorst plaques), 22.2% in group 2 (CRAO), 45% in group 3 (AF), and 9.8% in group 4 (nonspecific visual symptoms) had significant carotid disease and underwent carotid endarterectomy. No patient who underwent screening carotid duplex and did not have surgically correctable disease developed significant carotid disease or symptoms from carotid disease during the study period. Hollenhorst plaques, CRAO, and nonspecific visual complaints are a poor predictor of significant carotid stenosis, while AF had a significantly higher rate of surgically correctable carotid stenosis. Patients with visual signs or symptoms need an initial screening carotid duplex examination. If this does not show surgically correctable disease, patients do not need to return for further examinations unless another indication arises. Presented at the Thirteenth Annual Winter Meeting of the Peripheral Vascular Surgery Society, Snowmass, CO, January 31-February 2, 2003.     

Surgical management of the occluded carotid artery

Of 36 patients with symptomatic total occlusion of the common carotid and/or internal carotid arteries, ipsilateral operation was performed in 20. Twenty-eight patients had occlusion of the internal carotid artery, four of the common carotid alone, and four had occlusion of both vessels. Thirteen patients had completed stroke. Noninvasive examination erroneously suggested internal carotid patency in three patients. Of six patients with occluded common carotid arteries, two underwent thromboendarterectomy, two underwent saphenous vein bypass, and two underwent Dacron graft bypass procedures. Five patients underwent attempted internal carotid thromboendarterectomy and three patients underwent external carotid endarterectomy. Seven patients underwent primary temporal to middle cerebral bypass procedures. There were no perioperative deaths and no patients had permanent neurologic deterioration. There were two postoperative complications. At follow-up 1 to 43 months after operation, five of six patients who had undergone common carotid revascularization had improved neurologically while other treatment groups had no definite improvement. Revascularization of an occluded common carotid artery is a safe procedure that successfully alleviates symptoms of cerebral ischemia. Internal carotid disobliteration and external carotid endarterectomy alone provide limited neurovascular benefit. Benefits of extracranial-to-intracranial bypass were not apparent from this small series.     

Clinical implications of power Doppler three-dimensional ultrasonography

Power Doppler ultrasonography displays an estimate of the entire power contained in that part of the received radiofrequency ultrasound signal for which a phase shift corresponding to the motion of the target is detected. In contrast, conventional color Doppler imaging displays Doppler frequency shift information. Few reports have been published on the clinical utility of three-dimensional power Doppler ultrasonography in vascular patients. This study analyzed our experience of the clinical utility of this technology. Fifty-three patients selected out of 281 who were referred to our vascular laboratory underwent both conventional color duplex ultrasonography and power Doppler ultrasonography for the following indications: the question of subtotal versus total arterial occlusion, tortuous artery with limited imaging on color duplex ultrasonography, the presence of significant disease by Doppler ultrasonography with limited imaging, deep-lying arteries with an obscure orifice (e.g., renal artery), and heavily calcified arteries. The power Doppler ultrasonography portion of the examination was considered of positive diagnostic value if the final impression was different from that of conventional color duplex ultrasonography. A positive diagnostic value was achieved in 22 of 29 (76%) carotid artery examinations, 10 of 14 (71%) peripheral artery examinations, 4 of 5 (80%) renal artery examinations, and 3 of 5 (60%) aortoiliac examinations. Overall, positive diagnostic value was achieved by adding power Doppler ultrasonography in 39 of 53 patients (74%). Five of six patients (83%) who were felt to have carotid occlusion by color duplex ultrasonography were confirmed to have subtotal occlusion by power Doppler ultrasonography. Similarly, 6 of 8 patients (75%) with questionable subtotal versus total peripheral arterial occlusion by color duplex ultrasonography were confirmed to have subtotal occlusion by power Doppler ultrasonography. Four of five patients' (80%) renal examinations had a positive diagnostic value, which included three patients in whom the orifice of renal arteries was not seen by color duplex ultrasonography. Three-dimensional power Doppler ultrasonography can be more readily applied to clinical practice. Power Doppler ultrasonography is capable of defining the severity or extent of vascular disease, particularly in differentiating subtotal from total arterial occlusion.