Color Doppler ultrasound velocimetry of internal carotid arteries in normal pregnancies

BACKGROUND: There are few reports on maternal cerebral circulation during pregnancy. Using the hypothesis that cerebral blood flow resistance decreases progressively with advancing gestational age (GA) as a consequence of estrogenic effects on the vascular system during pregnancy, we calculated the pulsatility index (PI) and the mean velocity (MV) of the maternal right internal carotid artery (ICA) in order to build fitted reference centiles. METHODS: A total of 315 pregnant women with a single fetus were studied at 20-42 weeks' gestation. The patients had uncomplicated singleton pregnancies and were without any known fetal or maternal risk factors. Duplex color ultrasound with a pulsed Doppler scanner (7.5 MHz) was used to determine the PI and MV of the maternal ICA. RESULTS: Among the 315 healthy pregnant women, the PI of maternal ICA decreased progressively with advancing GA, PI50th = Exp (0.3124-0.0084 x GA), (p = 0.0003), during the second half of pregnancy. The predicted 50th percentile PI values of the ICA decreased from 1.117 (5th% = 0.755, 95th% = 1.654) at 24 weeks' gestation to 0.917 (5th% = 0.659, 95th% = 1.448) at 40 weeks' gestation. The MV of the maternal ICA also decreased progressively with advancing GA, MV50th = Exp (3.855-0.0093 x GA), (p = 0.0005), during the second half of pregnancy. The predicted 50th percentile MV values in the ICA decreased from 37.811 cm/sec (5th% = 24.177 cm/sec, 95th% = 59.138 cm/sec) at 24 weeks' gestation to 32.591 cm/sec (5th% = 20.818 cm/sec, 95th% = 51.021 cm/sec) at 40 weeks' gestation. CONCLUSIONS: Both the PI and MV of the maternal ICA decreased with GA during the second half of normal pregnancy as a result of intracerebral vessel dilatation.     

Utility of Pilot wire in angioplasty of tortuous and highly angulated coronary arteries

We present a case of severe proximal circumflex artery tortuosity with two 90 degrees bends and then a tight stenosis in the mid part of first obtuse marginal branch. Conventional method used to cross the lesion by wire failed. However, a commercially available new wire with ability to change the degree of tip angulation (Pilot wire, USCI Bard) was then used successfully to cross the stenosis. In addition, the wire straightened the tortuosities and provided good trackability to the balloon. Thus, this new wire is a valuable addition to the angioplasty armamentarium.     

Stenosis of the internal carotid arteries and cardiovascular risk factors in a group of patients aged 65 years and over

BACKGROUND: In the present study, the degree of stenosis of internal carotid arteries and the presence of cardiovascular risk factors are examined. METHODS: Two hundred patients underwent high resolution B-mode echotomography of the carotid arteries; furthermore, the presence of associated cardiovascular risk factors was considered. RESULTS: Small stenosis (< 16%) were reported in 113 (56.5%) patients; moderate stenosis (16-49%) were reported in 58 (29%) patients; severe stenosis (50-79%) were reported in 19 (9.5%) patients; subocclusive stenosis (80-99%) were reported in 2 (1%) patients; occlusions were reported in 8 (4%) patients. One hundred and fifty patients (75%) presented one or more associated cardiovascular risk factors. Hypertension was present in 122 (61%) patients; hypercholesterolemia in 43 (21.5%) patients; diabetes mellitus in 41 (20.5%) patients; 26 (13%) patients were smokers. CONCLUSIONS: According to other studies, stenosis < 50% were the most frequent (85.5%) in the subjects examined. Stenosis > or = 50% were more frequent in males than females. Hypertension was the most frequent associated cardiovascular risk factor; therefore the degree of stenosis increased with the increasing number of cardiovascular risk factors.     

Angioplasty and stenting in the carotid and vertebral arteries

Carotid and vertebral artery percutaneous transluminal angioplasty and stenting are new, experimental techniques. Their potential uses are discussed and the results and complications reported to date are reviewed.     

Geometric characterization of stenosed human carotid arteries

RATIONALE AND OBJECTIVES: The geometry of stenosed carotid bifurcations was analyzed to determine average representations for several stenosis grades. METHODS: Film angiograms of 62 patients with internal carotid artery stenoses were digitized. Residual lumen boundaries were manually outlined. The outlines were processed with a computer to extract geometric measurements. The measurements were grouped according to stenosis grade and used to create average representations. RESULTS: Accuracy and precision of the outlining technique were +/- 0.020 common carotid diameters (CCD) and +/- 0.025 CCD, respectively. Maximum narrowing of the internal carotid artery occurred at 0.3 CCD +/- 1.5 (mean +/- standard deviation) distal to the flow divider. The region of significant narrowing extended axially 1.2 CCD +/- 1.0. Poststenotic dilatations were observed, with enlargement of 1.3 +/- 0.7 times the normal diameter of the distal internal carotid artery. A tendency toward smaller bifurcation angles with increasing stenosis severity was observed. CONCLUSION: Three-dimensional geometric models could be created for carotid bifurcations that were disease free (normal) and of arbitrary stenosis grade.     

Technique for arterial-phase contrast-enhanced three-dimensional MR angiography of the carotid and vertebral arteries

Our goal was to evaluate whether contrast-enhanced three-dimensional MR angiography using the MR Smartprep technique would enable us to obtain arterial-phase MR angiograms of the carotid and vertebral arteries. The study included 35 patients with suspected lesions of the neck in whom the MR Smartprep technique was used for MR angiography performed with a 1.5-T superconducting system. The tracker volume was placed primarily in the middle part of the right common carotid artery. The imaging volume was placed in a coronal direction to include the carotid and vertebral arteries from the aortic arch to the skull base. A centric phase-ordering scheme was used. Imaging times were 20 to 38 seconds for 14 patients and 11 to 16 seconds for 21 patients. By using a smaller tracker volume and an imaging time of less than 16 seconds, we were able to achieve a 100% successful triggering rate and to delineate selectively arterial-phase carotid and vertebral arteries with almost no venous contamination. Contract-enhanced 3-D MR angiography with the MR Smartprep technique was useful for showing arterial-phase carotid and vertebral arteries selectively.     

Atherosclerosis of the inferior epigastric and internal mammary arteries

Atherosclerosis of the inferior epigastric artery (IEA) and the internal mammary artery (IMA) was evaluated in 21 patients with coronary heart disease. Both arteries were used simultaneously in coronary artery bypass grafting. Histologic samples were obtained from the proximal and distal segments of IEA and from the distal segment of IMA. Morphologic findings in regard to atherosclerosis were classified semiquantitatively as normal (0), or luminal narrowing <25% (1), 25-50% (2) or >50% (3), or as overt atherosclerosis and calcification (4). Atherosclerosis was absent or minimal (1) in distal samples from both arteries. Only one IMA showed moderate (2) luminal atherosclerotic obstruction. Two samples from proximal IEA showed moderate (2) or severe (4) atherosclerotic changes which limited their use as free grafts. These finding suggest that atherosclerosis is minimal and comparable in distal IEA and IMA in their natural environments even in patients with coronary heart disease. The long-term effect of aortic pressure on free IEA graft is still unclear.     

Bilateral thrombosis of the internal carotid arteries after a closed trauma. Advantages of magnetic resonance imaging and review of the literature

OBJECTIVE: Hospital and physician experience have been linked to improved outcomes for persons with HIV. Because many HIV-infected patients receive care in clinics, we studied clinic HIV experience and survival for women with AIDS. DESIGN: Retrospective cohort study of women with AIDS whose dominant sources of care were clinics. Clinic HIV experience was estimated as the cumulative number of Medicaid enrollees with advanced HIV who used a particular clinic as their dominant provider up to the year of the patient's AIDS diagnosis: low experience (< 20 patients), medium (20-99 patients), high (> or = 100 patients). Proportional hazards models examined relationships between experience and survival. SETTING: A total of 117 New York State clinics. PATIENTS: A total of 887 New York State Medicaid-enrolled women diagnosed with AIDS in 1989-1992. MAIN OUTCOME MEASURE: Survival after AIDS diagnosis. RESULTS: In later study years (1991-1992), patients in high experience clinics had an approximately 50% reduction in the relative hazard of death (0.53; 95% confidence interval, 0.35-0.82) compared with patients in low experience clinics. Adjusting for demographic and clinical variables, 71% of patients in high experience clinics were alive 21 months after diagnosis compared with 53% in low experience clinics. Experience and survival were not significantly associated in the early study years (1989-1990). CONCLUSIONS: In more recent years, women with AIDS receiving care in high experience clinics survived longer after AIDS diagnosis than those in low experience clinics, providing further evidence of a relationship between provider HIV experience and outcomes.     

Pseudo-tandem stenosis of the internal carotid artery

Two cases of pseudo-tandem stenosis of the internal carotid artery are presented. Proximal stenosis was produced by a large, focal atherosclerotic plaque. The severe intracranial "stenosis" was thought to be an angiographic artifact. Repeat cerebral angiography after carotid endarterectomy revealed normal intracranial arteries. The recognition of this entity is important because a decision to operate is based largely upon angiographic findings.     

Angioplasty of the occluded internal carotid artery

PURPOSE: To review patients who have presented with acute strokes from a middle cerebral artery occlusion in whom in addition to the middle cerebral artery thromboembolus, an internal carotid artery occlusion has been present, and in whom angioplasty of these totally occluded internal carotid arteries has bee n successful. METHODS: We reviewed retrospectively our experience in treating a cute stroke patients with intracranial, intraarterial urokinase. Six of 27 patients had internal carotid artery occlusions in addition to middle cerebral artery occlusions. Two patients presented with spontaneous carotid dissections for wh ich no further intervention from the ipsilateral internal carotid artery was attempted. In the remaining four internal carotid artery occlusions secondary to atherosclerotic disease, standard guide wires and catheters were negotiated across the level of the internal carotid artery occlusion, which expedited intracranial catheterization for thrombolysis. Subsequently, angioplasty of the internal carotid artery was performed. RESULTS: All four occluded internal carotid arteries could be traversed. No new neurologic deficits occurred. No vascular injuries occurred. No deaths occurred. Four- to 6-month follow-up showed all four internal carotid arteries remained patent. CONCLUSION: In acute occlusions of the internal carotid artery from atherosclerosis, the occluded vessel can sometimes be recanalized with low morbidity. In addition, endovascular access to the intracranial circulation can be expedited by using the recanalized internal carotid artery.     

Penetrating trauma of the internal carotid artery

OBJECTIVE: To assess management of penetrating internal carotid artery (ICA) injuries. DESIGN: Retrospective review of institutional protocol. SETTING: Level 1 trauma center in a major urban area. PATIENTS: Sixty-one patients with penetrating ICA injuries. INTERVENTIONS: In the period 1975 to 1987 (group 1; n = 36), management was based on individual surgeons' preferences. Between 1988 and 1995 (group 2; n = 25), an algorithm was employed: (1) hemodynamically stable patients with suspected ICA injuries underwent a diagnostic angiography; (2) surgically accessible injuries were reconstructed regardless of neurologic status with 2 exceptions: (a) neurologically intact patients with ICA occlusion were treated by anticoagulation and mild pharmacological hypertension and (b) minimal nonocclusive injuries were managed nonoperatively and followed up by serial angiography or duplex ultrasonography; and (3) heparinization, shunting, and completion angiography were employed. MAIN OUTCOME MEASURES: Neurologic status at admission and discharge were compared by the Fisher exact test. RESULTS: In group 1, 24 patients (67%) presented neurologically intact, and 12 (33%) with a deficit. Sixteen injuries were managed nonoperatively, 14 were repaired, and 6 were ligated. At discharge 6 (17%) were improved, 24 (66%) were unchanged, 6 (17%) were worse. Four patients (11%) died of cerebrovascular causes. In group 2, 19 patients (76%) presented neurologically intact, and 6 (24%) with a deficit. Eleven injuries were managed nonoperatively, 12 were repaired, and 2 were ligated. A death occurred in a patient who arrested, was admitted to the hospital in a coma, and died before ICA repair. CONCLUSIONS: Neurologic outcome after ICA injury is enhanced by an algorithm predicated on the liberal use of angiography, a predefined surgical approach, and selective observation.     

Spontaneous dissection of the internal carotid artery

The arteriographic diagnosis of spontaneous, nontraumatic dissection of the internal carotid artery was made in 19 patients and confirmed at operation in ten. The tapered narrowing beginning in or about the carotid bulb and ending at the bony canal was a consistent finding. Four patients had associated aneurysm formation. All but one patient developed an acute hemispheric neurologic deficit as the initial symptom. The deficit was transient in ten and prolonged in eight. The dissection occurred in the outer layers of the media. None of the surgical specimens showed atherosclerosis. Surgical methods of management included segmental resection and grafting, thrombectomy and intimectomy, dilation, and simple ligation. Considerable improvement of luminal diameter occurred in six of seven patients whose arteries were left undisturbed.     

Ophthalmologic manifestations of internal carotid artery dissection

PURPOSE: To report the ophthalmologic symptoms and signs associated with extracranial internal carotid artery dissection. METHODS: One hundred forty-six consecutive patients with extracranial internal carotid artery dissection were evaluted; 29 were studied retrospectively from 1972 to 1984 and 117 prospectively from 1985 to 1997. RESULTS: Sixty-two percent of patients (91/146) with extracranial internal carotid artery dissection had ophthalmologic symptoms or signs that were the presenting symptoms or signs of dissection in 52% (76/146). Forty-four percent (65/146) had painful Horner syndrome, which remained isolated in half the cases (32/65). Twenty-eight percent (41/146) had transient monocular visual loss, which was painful in 31 cases, associated with Horner syndrome in 13 cases, and described as "scintillations" or "flashing lights"-often related to postural changes or exposure to bright lights-suggesting acute choroidal hypoperfusion in 23 cases. Four patients had ischemic optic neuropathy; one had diplopia. Among the 76 patients with ophthalmologic symptoms or signs as the presenting features of carotid dissection, a nonreversible ocular or hemispheric stroke later occurred in 27, within a mean of 6.2 days (range, 1 hour to 31 days). Eighteen patients had a stroke within the first week after the onset of neuro-ophthalmic symptoms and signs, and 24 had a stroke within the first 2 weeks. CONCLUSION: Ophthalmologic symptoms or signs are frequently associated with and are often the presenting features in internal carotid artery dissection. Painful Horner syndrome or transient monocular visual loss should prompt investigations to diagnose carotid artery dissection and begin early treatment to prevent a devastating ocular or hemispheric stroke.     

Duplication of the extracranial internal carotid artery

We describe a case of duplication of the left internal carotid artery from a point 1 cm distal to the origin to the proximal petrous segment where the vessel reunites. Duplication and fenestration of the internal carotid artery are discussed. A review of embryologic development is presented. Identification of these entities is important, especially in patients who require surgical intervention involving the internal carotid artery.     

Congenital absence of the internal carotid artery

The aim of this study was to adapt the single-breath technique with positive expiratory pressure to measure exhaled nitric oxide (eNO) in infants. We hypothesized that exhaled eNO was greater in wheezy than in healthy infants. We studied 30 infants (16 wheezy and 14 healthy). The forced expiratory volume in 0.5 s (FEV0.5) was determined with the raised volume rapid thoracic compression technique, and eNO was measured during constant expiratory flow with a rapid-response chemiluminescence analyzer. After passive inflation to a preset pressure of 20 cm H2O, thoracic compression with an inflatable jacket caused forced expiration to occur through a face-mask with an expiratory flow resistor attached. During the forced expiration, the jacket pressure was increased to maintain a constant driving mouth pressure and hence a constant expiratory flow (50 ml/s). The mean level of eNO in the wheezy infants (31.8 ppb) was significantly higher than the level in healthy infants (18.8 ppb) (p = 0.03). A family history of atopy in parents was associated with increased eNO levels (p < 0.001) independent of age, sex, weight, length, wheezing, and FEV0.5. We conclude that the single-breath technique with positive expiratory pressure is a feasible method for measuring eNO in infants. Levels of eNO were significantly higher in wheezy infants and in those with a family history of atopy.     

Study of microvascular polyester prosthesis in rat carotid arteries

The implantation of a microvascular polyester prosthesis (MPP) (internal diameter 1 mm, length 10 mm) in the carotid arteries was studied in 48 Sprague-Dawley rats. The left carotid artery was resected to 7 mm in length and replaced with MPP by means of sleeve anastomoses. Postoperatively the patency was monitored with Doppler ultrasound at 24 and 72 hr, and at 1, 2, 3, 4, 8, and 12 weeks and was confirmed either by direct inspection intraoperatively or by angiography at the time of removal. At each monitoring time, all the thrombosed and some selected patent grafts were removed and prepared for scanning electron microscopy (SEM) study. The early patency rate was 100% within 24 hr, and the cumulative long-term patency rate was 77.1% at 12 weeks. Rapid and complete endothelial lining (EL) restoration was demonstrated 3 weeks after operation, which provided a smooth and nonthrombogenic surface, and contributed to the long-term patency. Ten of the 11 failed grafts occurred within 3 weeks, that is, before EL, due to thrombosis. These observations indicate that MPP can be successfully used as arterial conduits in rats, and an enhanced patency rate may be expected with the use of anticoagulants or endothelial cell seeding for prevention of early thrombosis.