Study design validation for consolidating global with focal neurological events in cardiac surgery stroke risk factor analyses.

Neuroimaging shows that both global and focal neurologic deficits after cardiac surgery share an acute, often multifocal, embolic cerebral infarction etiology; yet, analyses of stroke risk factors historically have emphasized the focal deficits. We test if consolidating encephalopathy and coma with focal deficits affects four stroke risk factors and a dummy variable. Overall focal and global events in 575 cardiopulmonary bypass operations identified by retrospective review matched indices reported in large prospective studies. Logistic regression in 189 records selected for completed non-invasive preoperative carotid stenosis screening showed all four conventional stroke risk factors to be independent predictors of overall consolidated global plus focal neurologic risk, specifically: age [odds ratio (OR) 1.90 per decade], carotid stenosis >50% (OR 1.91), pump time (OR 1.67 per hour), open chamber (OR 1.95); and successfully eliminated the dummy variable gender (P = 0.6). This analysis indicates that the design of future stroke risk factor studies in the setting of cardiac surgery can and should adopt a neuroimaging evidence-based investigative approach of consolidating global with focal deficits.

Atherogenic progression of carotid stenosis associates selectively with monocyte fraction in circulating leukocytes.

Humoral biomarkers of inflammation appear to correlate with future cardiovascular events warranting investigation of more specific associations between phenotypic subclasses of circulating cellular immunity and atherogenic progression of carotid stenosis. Retrospective study of carotid stenosis progression based on archived serial carotid duplex ultrasonography examinations in 100 patients. Predictors of atherogenic progression of carotid stenosis were sought using univariate and multivariate analysis of age, gender, hypertension, diabetes mellitus, smoking, peripheral blood leukocyte count and leukocyte differential profile, platelets, diastolic and systolic and mean arterial blood pressure, pulse pressure, creatinine, glucose, total-, HDL-, and LDL-cholesterol, triglycerides, and body mass index. Atherogenic progression of carotid stenosis was limited to patients with carotid stenosis at baseline (41/100) and exhibited a sporadic episodic temporal course. Univariate predictors of stenosis progression were diabetes mellitus, smoking, percent monocytes, and absolute monocyte count. Logistic regression demonstrated that monocytes as a percentage of circulating leukocytes [odds ratio (OR) 1.25, 95% confidence interval (CI) 1.06-1.47, P=0.0093] and smoking (OR 7.09, 95% CI 1.97-25.43, P=0.0027) were independently associated with atherogenic epochs. A selective association between the fraction of monocytes among leukocytes in peripheral blood and atherogenic progression of carotid stenosis is described.

Acute effects of smoking on human cerebral blood flow: a transcranial Doppler ultrasonography study.

Middle cerebral artery (MCA) flow velocity was continuously monitored during smoking in an observational study (n = 14) using transcranial Doppler (TCD) ultrasonography. Cerebral autoregulatory vasodilator capacitance under inspired CO2 challenge was also measured before smoking and at peak smoking effect. Several puffs on a single lighted cigarette over a period of five minutes acutely increased MCA mean flow velocity in every subject (group mean increase: 19%, individual increases ranged 2-64%) with a response onset and offset detectable within several seconds of beginning and ending smoking. The mechanism for the increase in MCA flow velocities appeared to be independent of the CO2 autoregulatory mechanism. Gender subgroup analysis showed smoking acutely suppressed the CO2 vasodilator capacitance by 56% in men but only by 5% in women (p = 0.05). The magnitude of the acute smoking-induced increases in MCA flow velocities appeared to be independent of the estimated cigarette yields for nicotine, carbon monoxide, and "tar." Smoking in healthy subjects acutely increased MCA mean flow velocity, which may reflect a global increase in cerebral blood flow via complex influences on the cerebral autoregulation.

Venous thromboembolic disease after hybrid hip arthroplasty with negative duplex screening.

Postoperative duplex ultrasonography screening after total hip arthroplasty has been shown to identify patients who may require treatment or additional monitoring for venous thromboembolic disease. The potential for manifestation of venous thromboembolic disease subsequent to screening remains a concern. The objective of this study was to determine the prevalence of symptomatic venous thromboembolic disease after total hip arthroplasty and after inhospital prophylaxis, inhospital screening with negative results for proximal deep venous thrombosis, and no posthospitalization venous thromboembolic disease prophylaxis. One hundred fifty patients undergoing primary hybrid total hip arthroplasty and using pneumatic compression stockings and aspirin as prophylaxis against venous thromboembolic disease were screened for deep venous thrombosis with duplex ultrasonography on the fourth day after surgery. Duplex ultrasonography screening revealed 17 (11.3%) patients with asymptomatic proximal deep venous thrombosis. In response to duplex ultrasonography screening, these patients with proximal deep venous thrombosis received therapeutic anticoagulation. Of 133 patients with a duplex screen with negative results for proximal deep venous thrombosis, 131 (98.5%) continued to have no symptoms of venous thromboembolic disease and two (1.5%) began to have symptoms for venous thromboembolic disease (one with proximal deep venous thrombosis, one with nonfatal pulmonary embolism) during 12 months of clinical followup after total hip arthroplasty. The overall prevalence of venous thromboembolic disease requiring anticoagulation was 19 of 150 (12.6%) patients. The remaining 131 (87.4%) were not exposed to the risks of postoperative anticoagulation and did not have subsequent symptomatic venous thromboembolic disease.

Screening for abdominal aortic aneurysms during lower extremity arterial evaluation in the vascular laboratory.

PURPOSE: The purpose of this study was to evaluate the cost-effectiveness of screening for abdominal aortic aneurysms (AAA) during noninvasive lower extremity arterial examination in the vascular laboratory. METHODS: Over 30 months we screened 531 patients who underwent lower extremity arterial evaluations in the vascular laboratory. The patients had fasted overnight, and, after the regular noninvasive lower extremity arterial examination, the abdominal aorta was screened with B-mode ultrasonography. RESULTS: The aorta was adequately visualized in 475 patients (89%). Mean aortic diameter was 19.6 +/- 4.1 mm at the juxtarenal level and 18.8 +/- 7.2 mm in the lower infrarenal aorta. The aortic diameter was larger in men (p < 0.001) and in smokers (p < 0.001). AAA (diameter greater than 3.0 cm) were identified in 32 patients (6.0% of the 531 patients screened), and 15 of the aneurysms were equal to or larger than 4.0 cm. The best predictors for AAA by logistic regression analysis were male sex (p < 0.005), advanced age (greater than 65 years, p < 0.01), and a history of smoking (p < 0.01). The prevalence of AAA was 6.7% (32/475) in the population in whom the aorta was visualized and 15.2% (19/125) in male smokers over 65 years of age. Aneurysms of 4.0 cm or greater were identified in 3.2% of the entire population screened and 8.8% of male smokers over age 65. Limited aortic scanning prolonged the vascular laboratory examination by an average of 5 minutes. Thus detection of one aneurysm required 83 minutes of scanning time for the whole population studied and 36 minutes of scanning of male smokers over age 65, at a cost of $240 to $553 per aneurysm identified. CONCLUSION: Screening for AAA during lower extremity arterial evaluation in the vascular laboratory addresses a high-risk population, is cost-effective, and should be considered an appropriate and valuable addition to the examination protocol.

Carotid steal syndrome: a case study.

The progression of subclavian arterial stenosis and the subsequent formation of collateral pathways serve to alter the pressure gradients in subclavian steal syndrome, altering ipsilateral vertebral artery flow from its normal state to "latent," "transient," and "continuous" steals. A similar altered flow in the carotid arteries can be observed with stenosis of the proximal common or innominate artery. A 59-year-old man was seen in the vascular laboratory for evaluation of symptomatic peripheral arterial disease. An incidental asymptomatic stenosis of the right innominate and left proximal subclavian artery was found. Further cerebral vascular evaluation displayed a continuous right subclavian steal and a latent steal in the right internal carotid artery. Transcranial Doppler examination displayed "transient" steal in the terminal right internal carotid artery. Combining duplex and transcranial Doppler evaluations allows sequential evaluation of the progression of arterial disease and its effect on the flow patterns in the cerebral vasculature.

Occurrence of fever associated with thermoregulatory dysfunction after acute traumatic spinal cord injury.

The medical records of 156 patients with acute traumatic Spinal Cord Injury (SCI), admitted for inpatient SCI rehabilitation during the period from January 1, 1990 through December 31, 1992, were retrospectively reviewed. Seventy-one patients with acute traumatic SCI were identified at risk for thermoregulatory dysfunction (50 patients with cervical SCI and 21 with upper thoracic level SCI). A total of 713 days were documented in which febrile events occurred in 60 of 71 patients during the study period. Over 39% of these fevers measured 101 degrees F (38.3 degrees C) or greater. There were 71 days of documented febrile episodes occurring in 17 patients for which an etiology could not be determined. Fifteen of these individuals had fewer than five such febrile days each during their entire rehabilitation hospitalization. Study results indicate that in a population of patients with acute traumatic SCI at risk for thermoregulatory dysfunction, the occurrence of fever is quite high. Fever not attributable to infectious or inflammatory etiologies is uncommon. Fever attributable to thermoregulatory dysfunction in this setting should be considered only after other etiologies have been carefully excluded.

Measurement of anterior and posterior circulation flow contributions to cerebral blood flow. An ultrasound-derived volumetric flow analysis.

Ultrasound-derived volumetric flow analysis may be useful in answering questions of basic physiological interest in the cerebrovascular circulation. Using this technique, the authors have sought to describe quantitatively the complete concurrent flow relations among all four arteries supplying the brain. The aim of this study of normal subjects was to determine the relative flow contributions of the anterior (internal carotid arteries) and posterior (vertebral arteries) cerebral circulation. Comparisons between the observed and theoretically expected anterior and posterior flow distribution would provide an opportunity to assess traditional rheological conceptions in vivo. Pulsed color Doppler ultrasonography was used to measure mean flow rates in the internal carotid and vertebral arteries in 21 normal adults. The anterior circulation (internal carotid arteries bilaterally) carried 82% of the brain's blood supply and comprised 67% of the total vascular cross-sectional area. These values demonstrate precise concordance between observations in vivo and the theoretically derived (Hagen-Poiseuille) expected flow distribution. These cerebrovascular findings support the traditional conception of macroscopic blood flow. Further studies using ultrasound-derived volumetric analysis of the brain's arterial flow relations may illuminate the vascular pathophysiology underlying aging, cerebral ischemia, and dementias.

Postoperative surveillance for deep venous thrombosis with duplex ultrasonography after total knee arthroplasty.

Duplex ultrasonography of the lower extremity was used for routine non-invasive screening for asymptomatic proximal and distal deep venous thrombosis, for monitoring of potential propagation of deep venous thrombosis from distal to proximal, and for confirmation of the resolution of proximal deep venous thrombosis after treatment. In the first part of the study, to substantiate the accuracy of duplex ultrasonography, 130 lower limbs (seventy-nine patients) were studied with that modality as well as with venography after a total hip or total knee arthroplasty. Compared with venography, duplex ultrasonography demonstrated 100 per cent sensitivity, specificity, and accuracy for the detection of proximal deep venous thrombosis and 88 per cent sensitivity, 98 per cent specificity, and 98 per cent accuracy for the detection of distal deep venous thrombosis. In the second part of the study, 100 patients who had had a total knee arthroplasty and had been managed with pneumatic stockings and aspirin for prophylaxis against deep venous thrombosis had screening of both lower extremities with duplex ultrasonography on the fourth postoperative day. Duplex ultrasonography demonstrated proximal deep venous thrombosis in seven patients and distal deep venous thrombosis in twenty-two patients; all twenty-nine patients were asymptomatic. The patients who had distal deep venous thrombosis had surveillance with serial duplex ultrasonography on the seventh and fourteenth postoperative days; five of these patients were found to have had propagation of the thrombosis to the proximal deep veins.(ABSTRACT TRUNCATED AT 250 WORDS)

The clinical course of distal deep venous thrombosis after total hip and total knee arthroplasty, as determined with duplex ultrasonography.

Duplex ultrasonography was used to screen 273 consecutive patients, on the fourth day after a total hip or total knee arthroplasty, for the presence of a distal deep venous thrombosis. Patients who had a history of thromboembolic disease or who had an active neoplasm were excluded from the study. Of the 273 patients, twenty-four (9 per cent) were found to have a proximal deep venous thrombosis (a thrombosis involving the femoral or popliteal veins) and forty-one (15 per cent), a distal deep venous thrombosis (a thrombosis involving the veins of the calf). All of the thromboses were asymptomatic. The forty-one patients in whom a distal deep venous thrombosis had been detected with duplex screening subsequently had serial duplex examinations, on the seventh and fourteenth postoperative days. If a proximal deep venous thrombosis was detected, anticoagulation was begun immediately. If no proximal thrombosis was observed, the distal thrombosis was considered stable, the serial duplex examinations were terminated, and clinical observation was continued. Of the forty-one patients who had serial examinations, seven (17 per cent) had a proximal deep venous thrombosis in the ipsilateral limb by the fourteenth postoperative day; all seven were asymptomatic, and all were managed with anticoagulation. Thirty-four patients (83 per cent) were determined to have a stable distal deep venous thrombosis on the fourteenth postoperative day, and no additional duplex examinations were performed. Thirty-three (97 per cent) of these thirty-four patients remained asymptomatic for deep venous thrombosis thereafter; the remaining patient (3 per cent) had a proximal deep venous thrombosis in the ipsilateral limb eleven months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Routine postoperative duplex ultrasonography screening and monitoring for the detection of deep vein thrombosis. A survey of 110 total hip arthroplasties.

The use of duplex ultrasonography for routine noninvasive screening, monitoring, and management of deep venous thrombosis after total hip arthroplasty was evaluated. The reliability of duplex ultrasonography for detection of deep vein thrombosis was confirmed in an initial cohort of 51 total hip arthroplasty patients (102 lower extremities), demonstrating 91% sensitivity, 98% specificity, and 97% accuracy when compared with venography. A second cohort of 110 total hip arthroplasty patients using pneumatic compression stockings and aspirin as deep vein thrombosis prophylaxis underwent screening duplex ultrasonography of both lower extremities on postoperative Day 4. Duplex ultrasonography screening showed 10 (9.1%) patients with proximal deep vein thrombosis and 10 (9.1%) with distal deep vein thrombosis, all of whom were asymptomatic. The 10 patients with proximal deep vein thrombosis on duplex ultrasonography were prescribed therapeutic anticoagulation. Duplex ultrasonography subsequently confirmed resolution of proximal deep vein thrombosis in these patients before discontinuation of anticoagulation; none developed symptomatic pulmonary embolism through 12-month clinical followup. The 10 patients with distal deep vein thrombosis diagnosed by duplex ultrasonography were not treated with anticoagulation, but were monitored by serial duplex ultrasonography through postoperative Day 14 for propagation of distal to proximal deep vein thrombosis; none manifested symptomatic deep vein thrombosis or pulmonary embolism through 12-month clinical followup. The 90 patients with negative duplex ultrasonography results were followed clinically; 3 developed late symptomatic proximal deep vein thrombosis (1 of these later manifested pulmonary embolism). Therefore, duplex ultrasonography was used after total hip arthroplasty for the following: (1) to screen routinely in the hospital for asymptomatic proximal and distal deep vein thrombosis; (2) to monitor for potential propagation of distal to proximal deep vein thrombosis; (3) to minimize exposure to therapeutic anticoagulation by confirming the absence of proximal deep vein thrombosis in 97 of 110 patients; and (4) to demonstrate the effectiveness of mechanical and systemic deep vein thrombosis management by confirming the absence or resolution of deep vein thrombosis in all 110 patients.

Color duplex sonographically guided obliteration of pseudoaneurysm.

Over a 21 month period, 112 patients were seen in the vascular laboratory for evaluation and therapy of possible pseudoaneurysm. Pseudoaneurysm was confirmed by color flow sonographic imaging in 31 patients. Twenty-eight of these patients underwent sonographically monitored extrinsic manual compression to induce thrombosis and subsequent obliteration. Complete manual thrombosis was achieved in 17 patients while partial thrombosis with subsequent spontaneous closure developed in three patients, for a total success rate of 71% (20/28). In eight patients attempts to thrombose the pseudoaneurysm failed (29%). Induction of thrombosis by manual compression was successful in the presence of oral and intravenous anticoagulants. No therapeutic complications were encountered. Under proper sonographic guidance, the technique of manual obliteration of pseudoaneurysms provides a safe and effective alternative to surgical intervention.

Transcranial Doppler ultrasound and magnetoencephalography in migraine.

Eighty subjects--30 migraineurs during the attack, 30 patients in the interictal period, and 20 healthy volunteers--were studied using two technologies for functional assessment: transcranial Doppler ultrasound and magnetoencephalography. Transcranial Doppler studies showed an increased mean flow velocity at rest (p less than 0.05) in the middle cerebral artery on the side of the headache and a decreased vasomotor response to CO 2 (p less than 0.001) on the same side compared to control subjects. Biomagnetic measurements of somatosensory evoked fields of 11 patients and 11 control subjects in this study did not demonstrate differences between migraineurs and the control group in current flow or latency measures. The data from this study tend to support the hypothesis of vascular disease as a primary underlying deficit in migraine.

Embolic stroke as a sequela of cardiopulmonary bypass.

Tha pathophysiology of brain injury in patients undergoing cardiopulmonary bypass remains unclear despite several decades of inquiry. The advent of noninvasive high-resolution brain and cerebrovascular imaging by magnetic resonance, computed tomography, and pulsed Doppler ultrasonography now permits in vivo assessment of pathophysiological mechanisms. Neuroradiographic and carotid duplex studies were performed in patients who developed neurological deficits following cardiopulmonary bypass. Among 30 symptomatic patients undergoing magnetic resonance or computed tomography brain scans, 18 (60%) had findings of acute ischemic injury. Embolic infarction was evident in 14 (78%) of these 18 patients. Watershed injury was the predominant finding in a single patient, while findings consistent with global anoxia were present in another patient. Carotid atheroemboli were excluded as a possible source of embolism in 11 patients whose carotid duplex studies were unremarkable preoperatively as well as in 3 further patients whose neuroradiographic findings did not correspond with their moderate carotid disease. It is concluded that infarction due to noncarotid embolism is the primary pathophysiology of neurological deterioration following cardiopulmonary bypass.

Failure of aspirin plus dipyridamole to prevent restenosis after carotid endarterectomy.

OBJECTIVE: To evaluate therapy with aspirin plus dipyridamole in reducing restenosis after carotid endarterectomy. PATIENTS: A total of 163 patients having 175 surgical carotid endarterectomies. INTERVENTION: Eighty-three patients (90 endarterectomies) were randomly assigned to receive oral aspirin, 325 mg, plus dipyridamole, 75 mg, beginning 12 hours preoperatively, followed by a second dose administered within 8 hours after the operation, and given three times daily thereafter for 1 year. Eighty patients (85 endarterectomies) received placebo medication that was identical in appearance to the study drugs. MEASUREMENTS: After the adequacy of the surgical procedure was confirmed by intraoperative angiography, restenosis at the endarterectomy sites was evaluated using serial duplex ultrasound studies before hospital discharge and at 3-month intervals postoperatively for 1 year. RESULTS: Based on the time for developing identifiable restenosis and on efficacy analysis, greater than 50% restenosis developed in 11 operated vessels (16%) in the treated group and in 10 arteries (14%) in the placebo group, yielding an observed risk increase of 14% (95% CI, -52% to 167%; P greater than 0.2). By intention-to-treat analysis, greater than 50% restenosis developed in 16 of 90 operated vessels in treated patients and in 10 of 85 arteries in patients receiving placebo (26% for the treated group and 12% for the placebo group; P = 0.18, Mantel-Haenszel statistic), representing an observed risk increase of 110% (CI, -5% to 365%). Similar differences were observed for greater than 20% restenosis and for the comparison of patients rather than operated vessels by either intention-to-treat or efficacy analyses. CONCLUSIONS: Because therapy not only failed to reduce carotid restenosis but may have actually increased its frequency, treatment with aspirin plus dipyridamole probably has no clinically important benefit on restenosis in patients having carotid endarterectomy.

Noninvasive evaluation of vertebrobasilar insufficiency.

The diagnosis of vertebrobasilar insufficiency (VBI) is a clinical challenge because its manifestations are subjective and difficult to quantify. We evaluate 61 patients with the clinical diagnosis of VBI and 30 control patients with other medical problems. We used duplex scanning to study the extracranial carotid, vertebral, and subclavian arteries, and a 2-MHz transcranial Doppler (TCD) to examine the intracranial vertebral and basilar arteries. Extracranial lesions were more common in VBI patients than among controls, including stenosis of the subclavian artery with and without subclavian-vertebral steal and stenosis of the vertebral artery. Intracranial abnormalities identified in the vertebrobasilar circulation included stenosis and occlusion of the intracranial vertebral artery and basilar artery steal. Overall, significant lesions were detected in 32.8% of VBI patients and 3.0% of controls (P less than 0.05). Systolic artery velocity (cm/sec) in the extracranial vertebral artery was higher in controls (65.9 +/- 23.3) than in VBI patients who had no evidence of vertebrobasilar steal (43.0 +/- 17.4, P less than 0.05). Patients with a steal mechanism had an intracranial vertebral artery systolic velocity of 90.0 +/- 38.9, compared with 53.0 +/- 15.0 in controls (2P less than 0.050). Intracranial vertebral artery systolic velocity was higher among VBI patients with significant carotid artery disease (greater than 50%, 76.7 +/- 28.8) than in those with less severe disease (less than 50%, 47.3 +/- 13.8, P less than 0.05). Evaluation and quantitation of the vertebrobasilar circulation using both intra- and extracranial noninvasive studies may afford further insight as to the pathophysiology of vertebrobasilar insufficiency and provide a readily available, direct, and simple method of initial and serial assessment of VBI patients.