The utility of preoperative routine carotid artery duplex scanning in patients undergoing aortic valve replacement

Patients with aortic valve disease (AVD) typically have a cardiac murmur that radiates to the neck and may be indistinguishable from a cervical bruit secondary to carotid artery occlusive disease. The purpose of this report was to determine the prevalence of significant asymptomatic carotid artery occlusive disease in patients undergoing aortic valve replacement (AVR). All patients scheduled for AVR were prospectively studied. Preoperative carotid artery color-flow duplex was performed in all patients. A total of 204 patients were included in the study and significant carotid disease (>50% stenosis of the internal carotid artery) was found in 17 (8%). In patients with isolated aortic valve disease, 4/129 (3%) had significant stenosis. Of the patients with concurrent aortic valve and coronary artery disease, 13/75 (17%) had significant stenosis. The incidence of significant carotid stenosis in patients with aortic valve disease was over five fold higher in patients with concurrent coronary artery disease (3% vs. 17%, p <0.001). The yield of routine carotid duplex scanning for patients undergoing isolated AVR is low. However, in the subset of patients with concurrent coronary disease, the yield is higher. This finding supports the use of routine carotid duplex scanning in patients with coexistent aortic valve and coronary artery disease.     

The clinical course of carotid bifurcation stenosis as determined by duplex scanning

Two hundred three patients had at least two carotid artery duplex (DS) examinations separated by at least 6 months (mean follow-up 18 months) and their risk factors, clinical outcome, and degree of carotid artery stenosis were compared. The accuracy of DS was established at greater than 90% by blinded comparison with angiography. During the study period 138 patients (68%) had stable carotid artery stenosis and 65 patients (32%) had progression of stenosis in at least one artery. Thirty patients had new symptoms of cerebrovascular disease (19 with transient ischemic attacks and 11 with stroke) during the study. It was not possible to predict which patients would become symptomatic on the basis of risk factor analysis or analysis of severity of stable carotid stenosis. Patients with progression of carotid artery stenosis to greater than 50% diameter reduction were significantly more likely (p less than 0.0001) to have new transient ischemic attack and stroke than were those with stable carotid artery stenosis, regardless of severity.     

Impact of duplex scanning on carotid endarterectomy

Duplex ultrasound permits safe and accurate assessment of the extracranial vasculature. This paper reports the change in patterns of referral to a specialized vascular unit following its introduction; increased referrals were seen in all specialties except neurology. A widely available and reliable duplex service has revealed more extracranial vascular disease than was previously recognized, and has increased referrals for carotid endarterectomy, thereby increasing surgical workload.     

The role of carotid duplex scanning in surgical decision making

Eighty-one patients suspected of having cerebrovascular disease had 157 carotid arterial systems studied by both duplex ultrasonography and contrast arteriography to better define the role of carotid duplex scanning in the surgical decision-making process. These studies were reviewed in a blinded fashion in conjunction with history and physical examination data by two surgeons, one operating on only symptomatic lesions, the other operating on both symptomatic and asymptomatic lesions. Results were analyzed to ascertain if there was agreement regarding decisions for carotid endarterectomy based on scan findings compared with decisions based on arteriographic findings. Scans were also compared with arteriograms and data were analyzed by decision matrix analysis. The accuracy of duplex scanning in relation to arteriography was 81% for detection of disease, 90% for the detection of ulceration, 83% for the detection of a critical stenosis, and 99% for the detection of total arterial occlusion. There was agreement between the two studies regarding the need for carotid surgery in 91% and 89% of carotid arteries, according to surgeons A and B, respectively. Regardless of the surgeons' indications for carotid endarterectomy, duplex ultrasonography provides sufficient information for proper surgical decision making in a high percentage of patients. The accuracy of duplex scanning and the risks of contrast arteriography suggest a possible future role for the routine use of duplex ultrasonography with selective utilization of arteriography in the surgical decision-making process in patients being evaluated for cerebrovascular occlusive disease.     

Screening of carotid arteries by noninvasive duplex scanning

This paper has reported the accuracy of the duplex scanner in diagnosing occlusive disease of the carotid artery. Patients who present with vague neurologic symptoms, syncopal episodes, or asymptomatic carotid bruits are candidates for this type of study to determine the presence of significant stenosis. Other indications include the continuing assessment of known lesions and postoperative results in patients who have had endarterectomies.     

Is duplex scanning sufficient evaluation before carotid endarterectomy?

Recent reports have suggested that cerebral angiography may not be necessary before carotid endarterectomy is performed in selected patients. To determine if arteriography provides additional information that might influence the decision to operate or the conduct of the operation, a retrospective review was performed of 100 consecutive patients undergoing cerebral angiography and carotid duplex scanning. Eighty of the 100 patients subsequently underwent carotid endarterectomy for neurologic symptoms or asymptomatic stenosis greater than 80%. Among the 20 patients not operated on, three would have undergone unnecessary surgery for mistaken diagnoses had the arteriogram not been obtained. Two other patients in this group of 20 would have had carotid endarterectomy for asymptomatic stenosis in the presence of an equally stenotic tandem lesion. Among the 80 patients operated on, an additional three had the operative procedure altered because arteriographic studies revealed pathologic findings outside the area of duplex scan examination. Thus the use of arteriography altered the management of eight (8%) patients in this group of 100.     

Renal duplex sonography: evaluation of clinical utility

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = -0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.     

Identifying total carotid occlusion with colour flow duplex scanning.

A major limitation of conventional duplex scanning is its inability reliably to differentiate severe stenosis from total occlusion of the internal carotid artery (ICA). Colour flow duplex scanning (CFS) facilitates the identification of internal and external carotid arteries, enables simultaneous evaluation of flow in multiple vessels in longitudinal and transverse views, and allows more accurate assessment of very low Doppler-shift frequencies with new "slow-flow" software technology. From July 1987 to January 1991, 9731 ICAs (4866 patients) were evaluated with CFS. Arteriography was performed in 483 of these patients (959 ICAs), and the results of the two studies were compared. Colour flow scanning was highly accurate in differentiating total occlusion from carotid stenosis. Eighty-two of 87 totally occluded ICAs were detected (sensitivity 94%) and 873 of 878 patient arteries were properly identified (specificity 99%). Positive and negative predictive values were 93 and 99%, respectively. False positive results (n = 6) were due to interpreter error (n = 4) and poor scanning technique (n = 2). All false negative results (n = 5) were the result of interpreter error. During the last 24 months of the study, no false positive or false negative results were detected, giving an accuracy of 100%. We conclude that CFS offers distinct advantages in the diagnosis of carotid occlusion, thereby overcoming the limitations of conventional duplex scanning in distinguishing total occlusion of the ICA from less severe disease, and is the method of choice for evaluating the carotid bifurcation.     

Spontaneous carotid dissection: duplex scanning in diagnosis and management

The clinical, duplex, and angiographic findings in six patients with seven spontaneous extracranial carotid artery dissections are reported. Four dissections resulted in internal carotid artery occlusion. These patients complained of ipsilateral headache followed by contralateral hemiplegia. The other three dissections involved the common carotid artery and resulted in dual (one true and one false) lumens. Two of these dissections were asymptomatic. All dissections were treated nonoperatively with anticoagulant therapy. Neurologic deficits improved or disappeared in all symptomatic patients. On follow-up studies, one of the four internal carotid occlusions completely resolved with normalization of the duplex examination. All three dual lumen dissections remained patent on serial studies. Diagnostic duplex characteristics, both conclusive and supportive, of carotid dissections are described. Duplex scanning is shown to be accurate in diagnosing and ideally suited for serially following spontaneous carotid dissections.     

'Fast track' carotid duplex scanning in a district general hospital

'Fast track' carotid scanning is designed to rapidly identify patients with significant symptomatic carotid stenosis and, thereby, allow prompt surgery. We review the outcome of patients referred to our open-access scanning service over 3 years and 6 months. A total of 807 cases (62% males and 38% females with a mean age of 64 years) were referred. The main presenting symptoms were TIA in 69%, amaurosis fugax in 11% and minor CVA in 8.3%. The mean time between referral and scan was 17 days. In 80% of the cases, the scan showed no significant disease and the patients were not seen in the clinic. Significant abnormality (stenosis > 70% or occlusion) was found in 20% of the patients. Of the total, 12% were reviewed in the out-patient clinic following which no action was taken, 2% had angiography but no surgery, while 5% had angiography and surgery. 1% were lost to follow-up. The mean delay from scan to operation was 36 days. CONCLUSION: Fast track scanning has led to early detection of surgically relevant carotid lesions and avoidance of delay in surgical intervention. It is an efficient and cost-effective practice.     

Assessment of ocular perfusion after carotid endarterectomy with color-flow duplex scanning

PURPOSE: The purpose of this study was to assess the effect of carotid endarterectomy (CEA) on ocular perfusion with the measurement of the ophthalmic artery (OA) and the central retinal artery (CRA) flow velocities with color-flow ocular duplex scanning (ODS). Ocular hemodynamics also were examined in a subset of patients with visual symptoms in an attempt to characterize the origin of the ocular symptoms and their response to surgery. METHODS: Twenty-five patients with internal carotid artery stenoses (>/=70%) underwent 29 CEAs. All the patients underwent ODS for the measurement of the peak systolic velocity (PSV) in the OA and the CRA of the ipsilateral eye before and after CEA. The preoperative and postoperative flow velocities were compared in all the patients and in the patients with and without visual symptoms. RESULTS: The preoperative PSV in the OA was 21.6 +/- 2.2 cm/s and in the CRA was 7.7 +/- 0.7 cm/s. These values were reduced as compared with normative values (OA, 37.8 cm/s; CRA, 10.7 cm/s). After CEA, the PSV increased significantly in both vessels (postoperative OA, 38.6 +/- 2.5 cm/s, P <.0001; postoperative CRA, 12.1 +/- 0.9 cm/s, P =.0008). Fifteen of the 29 CEAs were performed for visual symptoms. The patients with ocular symptoms had significantly lower preoperative PSVs in the CRA as compared with those patients without visual symptoms (CRA with ocular symptoms, 6.5 +/- 0.8 cm/s; CRA with no ocular symptoms, 9.4 +/- 0.9 cm/s; P =.02). The PSV in the OA was not significantly lower in the patients with ocular symptoms. Eight patients (28%) were found to have reversed OA flow before surgery, but only three patients had ocular symptoms. All eight patients had normal antegrade flow in the OA after surgery. CONCLUSION: Severe carotid stenosis may be associated with reduced ocular perfusion, which can be quantitatively evaluated with ODS. Reduced OA and CRA flow velocities are corrected with successful CEA. The patients with ocular symptoms were observed to have significant reductions in CRA flow velocities. Reversed flow in the OA was not a marker for ocular symptoms in this study. ODS can identify global ocular ischemia and may be helpful in the evaluation of patients with atypical visual symptoms or with amaurosis fugax and no evidence of retinal emboli.     

Can carotid duplex scanning supplant arteriography in patients with focal carotid territory symptoms?

Previous reports have suggested that duplex ultrasonography might supplant arteriography as a guide to operative decision making in selected patients with cerebrovascular disease. This study was undertaken to test that tenet in patients with focal carotid territory symptoms. Seventy-two patients having independently interpreted arch and selective carotid arteriography and duplex scanning underwent 78 carotid endarterectomies. Operative specimens were analyzed in all cases and used as the standard in evaluating the accuracy of the preoperative studies. All patients had disease found at the time of operation. The sensitivity of duplex scanning was 99% vs. 91% for arteriography (p = 0.06). In seven cases the scan accurately predicted disease in patients with normal arteriograms and in a single case the scan was read as normal in a patient with a smooth minimally stenotic plaque read as an irregular 30% stenosis on arteriography. The accuracy of duplex scanning was markedly superior to arteriography in detecting intimal surface abnormalities (92% vs. 64%, p less than 0.001) and ulceration (90% vs. 54%, p less than 0.001). There was no difference between duplex scan and arteriography (p = 1.0) in predicting a greater or less than 50% stenosis (accuracy, 94% for arteriogram; 92% for duplex scanning). Of the patients with preoperative potentially reversible symptoms, 97% were free of symptoms at a mean follow-up of 9 months after operation. Eighty-nine percent (17 of 19 patients) of patients with concomitant, ipsilateral, intracranial, or intrathoracic cerebrovascular disease were free of symptoms after carotid endarterectomy.     

Correlation of clinical findings, duplex carotid artery scanning and CT scanning of the brain in 54 consecutive patients with bruits over the carotid artery bifurcation.

Fifty-four patients presenting consecutively with bruits over the carotid artery bifurcation have been studied by Duplex ultrasonography of the carotid artery and CT of the brain. The patients were divided into symptomatic (transient ischaemic attacks (TIA), non-focal neurological symptoms, minor and major strokes) and asymptomatic groups. The duplex scans were subdivided into those showing a greater than 50% stenosis of the internal carotid artery and those with a less than 50% stenosis. The CT brain scans were subdivided into those showing evidence of cerebral infarction and those without. Symptomatic patients were found to be more likely to have an area of cerebral infarction than asymptomatic ones (P = 0.0086 Fisher's Exact Test). Patients with a significant stenosis (greater than 50%) of the internal carotid artery were more likely to have an ipsilateral cerebral infarction on CT than patients with a minor stenosis (less than 50% stenosis) (P = 0.028 Fisher's Exact Test). Three patients (two with TIA's and one with non-focal neurological symptoms) were found to have unsuspected cerebral infarcts on CT of the brain. These patients could theoretically be at risk following carotid endarterectomy and revascularization if the infarct were an early one. Patients with non-focal neurological symptoms and carotid bruit were more likely to have a significant stenosis than asymptomatic patients with carotid bruit (P = 0.0069 Fisher's Exact Test). Therapy should be directed at the carotid artery lesion in these cases. Duplex scanning of the carotid artery bifurcation may be combined usefully with CT brain scanning in the non-invasive investigation of patients with symptomatic extracranial carotid artery bruits.     

Open access carotid duplex scanning: throughput and resultant surgical workload

It is now generally accepted that high-quality duplex scanning obviates the need for pre-operative angiography in the assessment of most cases of carotid disease. An information leaflet was circulated to all general practitioners and hospital doctors in early 1996. Indications, results of treatment and details of the open access service were described. This paper outlines the workload that followed, for both imaging and surgical departments.     

Intraoperative duplex scanning after carotid artery reconstruction: A valuable tool

The operative management of extracranial cerebrovascular occlusive disease requires meticulous surgical technique. Intraoperative duplex imaging (10 MHz B-mode ultrasound combined with 7.5 MHz Doppler spectrum analysis) was used in an attempt to recognize technical problems that might result in serious neurologic injury. Eighty-four carotid arteries were studied in 76 consecutive patients undergoing carotid endarterectomy or reconstruction. Indications for operation included carotid territory transient ischemic attack (n = 36 [43%]), amaurosis fugax (n = 16 [19%]), stroke (n = 11 [13%]), asymptomatic stenosis (n = 11 [13%]), vertebrobasilar transient ischemic attack (n = 7 [8%]), recurrent stenosis (n = 2 [2%]), and trauma (n = 1 [1%]). Arterial anatomy was assessed ultrasonographically and duplex-derived velocity measurements were obtained to assess hemodynamics. Increased velocity measurement was noted to correlate with ultrasound image of stenosis. Technical errors were identified in 17 patients (22%), including six persons with residual internal carotid artery stenoses, three persons with hemodynamically significant stenoses caused by “kinked” internal carotid arteries, eight persons with debris or intimal flaps in their external carotid arteries, and one person with an occluded external carotid artery. The intraoperative duplex scan led to corrective measures during the surgical procedure in eight patients (11%). No new ipsilateral brain injury was noted in the 76 patients postoperatively. Intraoperative duplex scanning accurately identified residual stenosis, intraluminal thrombus, and loose debris. Duplex scanning altered intraoperative decision making in a significant proportion of patients studied. (J VASC SURG 1988;7:620-4.)     

Routine early postoperative duplex scanning is unnecessary following uncomplicated carotid endarterectomy

Although early postoperative duplex scanning has become routine after carotid endarterectomy (CEA), it is unclear whether the results of these scans alter clinical management. The purpose of this study was to critically examine the usefulness of early postoperative duplex scans in evaluating the ipsilateral carotid artery (for technical perfection) as well as the contralateral carotid artery (for potential velocity changes after improvements in ipsilateral flow). Consecutive patients undergoing CEA between January 1995 and June 1999 in a tertiary hospital setting were studied. Patients underwent early postoperative duplex scanning according to the discretion of the operating surgeon and the availability of the patient. In 212 patients 236 CEAs were performed with selective use of patch closure (49%), intraluminal shunting (19%), and intraoperative completion imaging studies (14%). Neurologic complications included 3 transient ischemic attacks (TIAs) (1.3%), 3 nondisabling strokes (1.3%), and 3 disabling strokes (1.3%). There was 1 30-day death from myocardial infarction. Patients were followed up for a median of 18 months (range 0-72 months). Sixty-five percent of patients undergoing uncomplicated CEA (147/227) underwent early duplex surveillance within 6 months of operation. Unsuspected sonographic abnormalities were discovered in 8 patients (5%), including 7 cases of mild internal carotid artery (ICA) stenosis (>50% by velocity criteria) and 1 case of common carotid artery (CCA) stenosis (intimal flap). None of the patients with ICA stenosis developed symptoms or required operation at any time. The CCA intimal flap was electively repaired without complication. Postoperative changes in velocity in the contralateral ICA were found in 8/48 (17%) cases. There were 3 cases of increased velocity, upgrading 1 from 0-49% to 50-79% stenosis and upgrading 2 from 50-79% to 80-99% stenosis. The latter patients both underwent uneventful contralateral CEA. There were 6 cases of decreased velocity, resulting in downgrading of stenoses from 50-79% to 0-49% (n=5) or from 80-99% to 50-79% (n=1). Only the latter patient underwent contralateral CEA; the remainder have been followed up without intervention. Early scanning appeared to offer no clinical benefit; survival and neurologic outcome were the same in the 135 patients scanned within the first 6 months as in the 68 patients whose first postoperative scan occurred later (4-year neurologic event rate 0% in both groups; patient survival with early duplex 98 +/- 1.5%, without early duplex 96 +/- 2.6%; = NS). Early ipsilateral duplex abnormalities following CEA are infrequent in asymptomatic patients and, even if found, rarely alter management. Patients with bilateral stenosis being considered for contralateral CEA should undergo repeat duplex scanning after the first operation, because of the significant rate (19%) of contralateral velocity changes induced by ipsilateral CEA.     

Accuracy of duplex scanning in the detection of stenosis after carotid endarterectomy

The results of duplex ultrasonography in grading stenosis after carotid endarterectomy (78 sites) were compared with those of contrast angiography in 71 patients studied for recurrent or contralateral occlusive disease of the carotid bifurcation. Duplex and angiographic studies were performed within one month of each other at a mean postoperative interval of 44 months (range 3 to 122 months). Stenosis of the common carotid (CCA) and internal carotid artery (ICA) was classified into five disease categories (normal or less than 15% diameter reduction [DR], 16% to 49% DR, 50% to 75% DR, greater than 75% DR, and occlusion). The overall accuracy of duplex scanning compared with angiography in predicting recurrent carotid bifurcation disease was 83%, a level of agreement similar to classification of disease involving the nonoperated, contralateral bifurcation (overall accuracy 87%). Recurrent stenosis (greater than 50% DR) or occlusion of the CCA or ICA after endarterectomy was identified with an accuracy of 97%. Overestimation of severity of recurrent stenosis accounted for 11 of 13 duplex classification errors (85%). Presence of moderate (30% to 50% DR) recurrent stenosis of the CCA, tortuosity of the ICA, and severe contralateral carotid bifurcation disease were associated with velocity spectra that predicted a more severe recurrent stenosis at the endarterectomy site compared with angiographic grading. The level of agreement between duplex scanning and angiography was comparable to the interobserver variability in angiographic interpretation. The accuracy reported justifies the use of duplex scanning to grade the severity of carotid bifurcation recurrent stenosis and to follow these lesions for disease progression.     

Role of duplex scanning in the selection of patients for carotid endarterectomy

A retrospective review of 63 patients undergoing duplex scanning and angiography for suspected carotid artery disease was performed to evaluate the need for routine angiography before carotid endarterectomy. A consultant surgeon (M.H.) made a simulated management decision on the basis of a clinical summary and a duplex scan report. Twenty-four patients were selected for surgery without angiography; duplex scanning had a sensitivity of 100 per cent and a specificity of 90 per cent in the detection of internal carotid artery stenosis. In two cases duplex scanning misdiagnosed a total occlusion as a critical stenosis. Eighteen patients failed to meet the criteria for surgery and were referred for angiography. Twenty-one patients were selected for conservative treatment on the basis of the duplex scan report. Combining the surgical and conservative groups (45 patients), duplex scanning had a sensitivity of 96 per cent and specificity of 95 per cent for the detection of stenosis greater than 50 per cent. In the identification of a total occlusion, duplex scanning had a poor sensitivity of 50 per cent. These results suggest that routine angiography before carotid endarterectomy is unnecessary in selected patients but that a suspected occlusion should be confirmed by angiography.