The Clinical Impact and Cost-Effectiveness of Surveillance of Incidentally Detected Gastric Intestinal Metaplasia: A Microsimulation Analysis

BACKGROUND & AIMS

Gastric intestinal metaplasia (GIM) is associated with a higher risk of noncardia intestinal gastric adenocarcinoma (GA). The aim of this study was to estimate lifetime benefits, complications, and cost-effectiveness of GIM surveillance using esophagogastroduodenoscopy (EGD).

METHODS

We developed a semi-Markov microsimulation model of patients with incidentally detected GIM, to compare the effectiveness of EGD surveillance with no surveillance at 10-year, 5-year, 3-year, 2-year, and 1-year intervals. We modeled a simulated cohort of 1,000,000 US individuals aged 50 with incidental GIM. Outcome measures were lifetime GA incidence, mortality, number of EGDs, complications, undiscounted life-years gained, and incremental cost-effectiveness ratio with a willingness-to-pay threshold of $100,000/quality-adjusted life-year (QALY).

RESULTS

In the absence of surveillance, the model simulated 32.0 lifetime GA cases and 23.0 lifetime GA deaths per 1000 individuals with GIM, respectively. Among surveilled individuals, simulated lifetime GA incidence (per 1000) decreased with shorter surveillance intervals (10-year to 1-year, 11.2-6.1) as did GA mortality (7.4-3.6). Compared with no surveillance, all modeled surveillance intervals yielded greater life expectancy (87-190 undiscounted life-years gained per 1000); 5-year surveillance provided the greatest number of life-years gained per EGD performed and was the cost-effective strategy ($40,706/QALY). In individuals with risk factors of family history of GA or anatomically extensive, incomplete-type GIM intensified 3-year surveillance was cost-effective (incremental cost-effectiveness ratio $28,156/QALY and $87,020/QALY, respectively).

CONCLUSIONS

Using microsimulation modeling, surveillance of incidentally detected GIM every 5 years is associated with reduced GA incidence/mortality and is cost-effective from a health care sector perspective. Real-world studies evaluating the impact of GIM surveillance on GA incidence and mortality in the United States are needed.

Pain, Analgesic Use, and Patient Satisfaction With Spinal Versus General Anesthesia for Hip Fracture Surgery : A Randomized Clinical Trial

BACKGROUND

The REGAIN (Regional versus General Anesthesia for Promoting Independence after Hip Fracture) trial found similar ambulation and survival at 60 days with spinal versus general anesthesia for hip fracture surgery. Trial outcomes evaluating pain, prescription analgesic use, and patient satisfaction have not yet been reported.

OBJECTIVE

To compare pain, analgesic use, and satisfaction after hip fracture surgery with spinal versus general anesthesia.

DESIGN

Preplanned secondary analysis of a pragmatic randomized trial. (ClinicalTrials.gov: NCT02507505).

SETTING

46 U.S. and Canadian hospitals.

PARTICIPANTS

Patients aged 50 years or older undergoing hip fracture surgery.

INTERVENTION

Spinal or general anesthesia.

MEASUREMENTS

Pain on postoperative days 1 through 3; 60-, 180-, and 365-day pain and prescription analgesic use; and satisfaction with care.

RESULTS

A total of 1600 patients were enrolled. The average age was 78 years, and 77% were women. A total of 73.5% (1050 of 1428) of patients reported severe pain during the first 24 hours after surgery. Worst pain over the first 24 hours after surgery was greater with spinal anesthesia (rated from 0 [no pain] to 10 [worst pain imaginable]; mean difference, 0.40 [95% CI, 0.12 to 0.68]). Pain did not differ across groups at other time points. Prescription analgesic use at 60 days occurred in 25% (141 of 563) and 18.8% (108 of 574) of patients assigned to spinal and general anesthesia, respectively (relative risk, 1.33 [CI, 1.06 to 1.65]). Satisfaction was similar across groups.

LIMITATION

Missing outcome data and multiple outcomes assessed.

CONCLUSION

Severe pain is common after hip fracture. Spinal anesthesia was associated with more pain in the first 24 hours after surgery and more prescription analgesic use at 60 days compared with general anesthesia.

PRIMARY FUNDING SOURCE

Patient-Centered Outcomes Research Institute.

Systemic acidemia impairs cardiac function in critically Ill patients

BACKGROUND

Acidemia, is associated with reduced cardiac function in animals, but no studies showing an effect of acidemia on cardiac function in humans are reported. In the present study, we examined the effect of acidemia on cardiac function assessed with transpulmonary thermodilution technique with integrated pulse contour analysis (Pulse Contour Cardiac Output, PiCCO™) in a large cohort of critically ill patients.

METHODS

This was a prospective multicenter observational cross-sectional study of 297 patients from 6 intensive care units in London, England selected from all patients admitted consecutively between May 2018 and March 2019. Measurements of lowest plasma pH and concurrent assessment of cardiac function were obtained.

FINDINGS

There was a significant difference between two pH categories (pH ≤ 7.28 vs. pH > 7.28) for the following variables of cardiac function: SVI (difference in means 32.7; 95% CI: 21 to 45 mL/m2; p < 0.001); GEF (18; 95% CI: 11 to 26%; p < 0.001), dPmax (-331; 95% CI: -510 to -153 mmHg/s; p = 0.001), CFI (0.7; 95% CI: 0.2 to 1.3 1/min; p = 0.01) and CPI (0.09; 95% CI: 0.03 to 0.15 W/m2; p < 0.001). However, there was no significant difference in CI (0.13; 95% CI: -0.20 to 0.47 L/min/m2; p = 0.12) between the pH categories. Also, a significant relationship was found between the quantitative pH and the following variables: SVI (132; 95% CI: 77 to 188 mL/m2; p < 0.001), GEF (74.7; 95% CI: 37.1 to 112.4%; p < 0.001), dPmax (-1587; 95% CI: -2361 to -815 mmHg/s; p < 0.001), CFI (3.5; 95% CI: 0.9 to 6.1 /min; p = 0.009), CPI (0.62; 95% CI: 0.36 to 0.88 W/m2; p < 0.001) and CI (regression coefficient 1.96; 95% CI:0.45 to 3.47 L/min/m2; p = 0.01).

INTERPRETATION

Acidemia is associated with impaired cardiac function in seriously ill patients hospitalized in the intensive care unit supporting the potential value of early diagnosis and improvement of arterial pH in these patients.

FUNDING

The study was partially supported by unrestricted funds from the UCLA School of Medicine.

Assessment of soil contamination by (210)Po and (210)Pb around heavy oil and natural gas fired power plants

Soil contamination by (210)Pb and (210)Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of (210)Pb and (210)Po were found to be the main source of surface soil contamination. The results showed that (210)Pb and (210)Po in fly-ash (economizer, superheater) is highly enriched with (210)Pb and (210)Po, while bottom-ash (boiler) is depleted. The highest (210)Pb and (210)Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, (210)Pb and (210)Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased.

Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block

BACKGROUND

Interscalene brachial plexus block (ISBPB) is an effective nerve block for shoulder surgery. However, a 100% incidence of phrenic nerve palsy limits the application of ISBPB for patients with limited pulmonary reserve. We examined the incidence of phrenic nerve palsy with a low-volume ISBPB compared with a standard-volume technique both guided by ultrasound.

METHODS

Forty patients undergoing shoulder surgery were randomized to receive an ultrasound-guided ISBPB of either 5 or 20 ml ropivacaine 0.5%. General anaesthesia was standardized. Both groups were assessed for respiratory function by sonographic diaphragmatic assessment and spirometry before and after receiving ISBPB, and after surgery. Motor and sensory block, pain, sleep quality, and analgesic consumption were additional outcomes. Statistical comparison of continuous variables was analysed using one-way analysis of variance and Student's t-test. Non-continuous variables were analysed using chi(2) tests. Statistical significance was assumed at P<0.05.

RESULTS

The incidence of diaphragmatic paralysis was significantly lower in the low-volume group compared with the standard-volume group (45% vs 100%). Reduction in forced expiratory volume in 1 s, forced vital capacity, and peak expiratory flow at 30 min after the block was also significantly less in the low-volume group. In addition, there was a significantly greater decrease in postoperative oxygen saturation in the standard-volume group (-5.85 vs -1.50, P=0.004) after surgery. There were no significant differences in pain scores, sleep quality, and total morphine consumption up to 24 h after surgery.

CONCLUSIONS

The use of low-volume ultrasound-guided ISBPB is associated with fewer respiratory and other complications with no change in postoperative analgesia compared with the standard-volume technique.

Hématome intracérébral spontané du sujet jeune

INTRODUCTION

Hemorrhagic stroke is uncommon in young patients. The etiologic spectrum is very wide in the literature. The purpose of this study was to determine the range of etiology in a group of patients completely investigated and to study the relation with a history of high blood pressure.

PATIENTS AND METHODS

We reviewed study database, clinical and diagnostic records of 130 patients identified in a population based study, aged 18 to 55 years presenting with hemorrhagic stroke. There were divided into two groups: 67 patients treated at Hotel-Dieu Hospital in Beirut, Lebanon, and 63 patients reviewed at Yale New Haven Hospital, Connecticut, USA. Patients presenting with selective subarachnoidal or intraventricular hemorrhage were excluded. Diagnostic evaluation was assessed for completeness (based on prospectively articulated evidence based criteria) and for identifiable etiology of hemorrhagic stroke and its relation to high blood pressure.

RESULTS

There were 84 cases (64%) with complete diagnostic workup. The most common cause of incomplete investigations in remaining cases was death, poor neurological condition and incomplete follow up. Hematoma was superficially located (lobar) in 59.2%, deep seated (thalamo-capsulo-lenticular) in 26%, within the brain stem in 8.7% and cerebellar in 6.1%. An etiology was established in 70.4% of cases (pial AVM 16.7%, aneurysms 15.5%, hematological disorders 13%, cavernous malformations 10.7%, tumors 4.8%, bleeding within ischemic area 3.8%, vasculitis 2.3%, venous thrombosis 1.2% and venous angioma 1.2%. 29.6% of patients remained with undetermined etiology despite complete investigations. In a subgroup of 45 patients, a history of high blood pressure was found in 46.7%. In this cohort, an underlying etiology was established in 71% of cases.

CONCLUSION

Complete investigation can establish an etiology in 70% of young patients who survived hemorrhagic stroke, independently from the presence of a history of high blood pressure.

Postoperative changes in visual evoked potentials and cognitive function tests following sevoflurane anaesthesia

We tested the hypothesis that minor disturbance of the visual pathway persists following general anaesthesia even when clinical discharge criteria are met. To test this, we measured visual evoked potentials (VEPs) in 13 ASA I or II patients who did not receive any pre-anaesthetic medication and underwent sevoflurane anaesthesia. VEPs were recorded on four occasions, before anaesthesia and at 30, 60, and 90 min after emergence from anaesthesia. Patients completed visual analogue scales (VAS) for sedation and anxiety, a Trieger Dot Test (TDT) and a Digit Symbol Substitution Test (DSST) immediately before each VEP recording. These results were compared using Student's t-test. P<0.05 was considered significant. VEP latency was prolonged (P<0.001) and amplitude diminished (P<0.05) at 30, 60, and 90 min after emergence from anaesthesia, when VAS scores for sedation and anxiety, TDT, and DSST had returned to pre-anaesthetic levels.

Advances in the genetics of cerebrovascular disease and stroke

MEDLINE searches identified epidemiologic, experimental, and clinical studies on the genetics of cerebrovascular disease and stroke, including the following topics: genetic epidemiology of stroke; genetics of systemic disorders that cause ischemic stroke, including coagulation disorders, connective tissue disorders, vasculopathies, metabolic disorders, and disorders of unknown etiology; and genetics of systemic disorders that cause hemorrhagic stroke. Recent discoveries in stroke genetics involve the genetic basis of monogenic disorders such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and sickle cell disease. Reproducing similar advances in other forms of cerebrovascular disease and stroke will be more difficult because their inheritance is complex, multigenic, and heterogeneous. However, the future is promising with the application of molecular genetic approaches such as linkage analysis, allele-sharing methods, association studies, and polygenic analysis of experimental crosses as well as the transmission/disequilibrium test--a statistical method for detection of linkage between a marker and a disease-susceptibility locus.

Topical amethocaine (Ametop) is superior to EMLA for intravenous cannulation. Eutectic mixture of local anesthetics

PURPOSE

A eutectic mixture of local anesthetics (EMLA) is commonly used to provide topical anesthesia for intravenous (i.v.) cannulation. One of its side effects is vasoconstriction, which may render cannulation more difficult. A gel formulation of amethocaine (Ametop) is now commercially available. The aim of this study was to compare EMLA and Ametop with regard to the degree of topical anesthesia afforded, the incidence of vasoconstriction and the ease of i.v. cannulation.

METHODS

Thirty two ASA I adult volunteers had a #16 gauge i.v. cannula inserted on two separate occasions using EMLA and Ametop applied in a double blind fashion for topical anesthesia. Parameters that were recorded after each cannulation included visual analogue pain scores (VAPS), the presence of vasoconstriction and the ease of cannulation, graded as: 1 = easy, 2 = moderately difficult, 3 = difficult and 4 = failed.

RESULTS

The mean VAPS +/- SD after cannulation with Ametop M was 12+/-9.9 and with EMLA was 25.3+/-16.6 (P = 0.002). Vasoconstriction occurred after EMLA application on 17 occasions and twice after Ametop (P = 0.001). The grade of difficulty of cannulation was 1.44+/-0.88 following EMLA and 1.06+/-0.25 with Ametop (P = 0.023).

CONCLUSIONS

Intravenous cannulation was less painful following application of Ametop than EMLA. In addition, Ametop caused less vasoconstriction and facilitated easier cannulation. Its use as a topical anesthetic agent is recommended, especially when i.v. access may be problematic.

The effects of EMLA and a topical formulation of 4% amethocaine (Ametop) on pain associated with retrobulbar injection

Retrobulbar block is commonly performed to provide anaesthesia for cataract extraction. This technique can cause significant discomfort. A prospective, randomised, placebo-controlled trial was carried out to investigate the efficacy of a eutectic mixture of local anaesthetics (EMLA) and a 4% amethocaine topical formulation (Ametop) in reducing the pain of retrobulbar injection. Ametop and EMLA proved to be of similar efficacy, both being superior to a placebo in alleviating the discomfort of retrobulbar block. No significant side-effects were observed with the use of either formulation.

Creutzfeldt-Jakob disease in the elderly

Creutzfeldt-Jakob disease (CJD) is typically described as a pre-senile dementia. However, cases do occur in the elderly and a case of sporadic CJD in an 86-year-old patient is described. The database of the UK national surveillance unit has been studied, and the age-specific incidences for various age groups over the period 1980-93 calculated. Cases of CJD in those over 80 years old have been identified and their clinical characteristics examined. There is no evidence that CJD presents atypically in the elderly, or that large numbers of cases are being missed in the elderly due to poor ascertainment.

Quantitative analysis of seizure frequency 1 week and 6, 12, and 24 months after surgery of epilepsy

We made quantitative analysis of seizure frequency 1 week and 6, 12, and 24 months after seizure surgery. Seizure recurrence was significantly higher when seizures occurred in the first postoperative week. Seizure recurrence increased progressively with longer follow-ups, but the 6 month postoperative follow-up period was an excellent index of long-term outcome. In operative follow-up studies, seizure frequency should be reported at fixed follow-up periods, e.g., at 6 months and 1, 2, 5, and 10 years. Meaningful comparison of outcomes between different studies is possible only when reports include outcome at fixed postoperative follow-up periods (as opposed to ranges of follow-up periods).

The effect of propofol on the electroencephalogram of patients with epilepsy

The effect of propofol on the electroencephalogram (EEG) in patients with epilepsy is still unclear. Case reports with electroencephalographic documentation highlight pro- and anticonvulsant effects and beta activation of the EEG. This prospective study sought to determine the effect of propofol in 17 patients undergoing cortical resection for intractable epilepsy. Each patient received 2 mg/kg of propofol intravenously and the EEG was recorded from chronically implanted subdural electrodes placed during a previous craniotomy. Frequency of interictal spikes, time to burst suppression, and appearance of beta activation were recorded. The median frequency of interictal spikes decreased significantly from 2 spikes/min before to 0 spikes/min after propofol (P = 0.001). Seizure activity did not increase after propofol. Profound burst suppression and an increase in beta activity were noted consistently. The use of propofol in patients with epilepsy seems to be safe but may interfere with the recording of EEG spikes.

Epilepsy surgery in children and adults

Epilepsy surgery is now accepted as a treatment modality for medically intractable epilepsy. A careful and detailed evaluation of patients is required by a trained epilepsy team which includes neurosurgeons, neurologists, neuroradiologists, psychologists and psychiatrists. For intractable complex partial seizures of temporal lobe origin, epilepsy surgery offers an 80% success rate.

MRI-guided stereotactic placement of depth electrodes in temporal lobe epilepsy

Electrodes placed stereotactically in mesial temporal lobe structures may be useful for determining laterality, and extent of the epileptogenic zone in temporal lobe epilepsy. We present and compare our experience with the use of two stereotactic arcs, the Brown-Roberts-Wells (BRW) and Cosman-Roberts-Wells (CRW) for magnetic resonance imaging guided placement of multicontact electrodes in the amygdala, anterior and posterior hippocampus. Out of 101 electrodes, 28 were placed in 6 and 17 patients using the BRW and CRW arcs, respectively. The target-centered design of the CRW arc eliminated the need for trajectory calculations, used uniform 'depth' measurements, and allowed greater operative flexibility and a shortened operating time. The use of depth electrode recording allowed 14 of the 23 patients to be selected for temporal lobectomy.

Intracarotid amobarbital procedure: I. Prediction of decreased modality-specific memory scores after temporal lobectomy

To assess predictive value of the intracarotid amobarbital procedure (IAP) for decreased postoperative modality-specific memory, we studied 37 temporal lobectomy patients with intractable partial epilepsy who were selected for operation independent of preoperative IAP findings. When ipsilateral IAP failure was defined by an absolute method as a retention score less than 67%, the results were not associated with decreased modality-specific memory after operation. When ipsilateral IAP failure was defined by a comparative method as a retention score at least 20% lower after ipsilateral than contralateral injection, the results showed greater differences between groups, but differences still did not achieve statistical significance. Four left-resection patients who failed the ipsilateral IAP had a median postoperative change in the Wechsler Memory Scale-Revised (WMS-R) Verbal Memory Index score of -14%, whereas 16 left-resection patients who passed the ipsilateral IAP had a mean postoperative change in the WMS-R Verbal Memory Index score of -7.5% (p = 0.12). These results suggested that the IAP interpreted comparatively may be a helpful adjunctive test in assessment of relative risk for modality-specific memory dysfunction after temporal lobectomy, but larger series of operated patients are needed to confirm this possibility. In this series, complete amnesia was not noted after ipsilateral injection, even in patients with postoperative modality-specific memory decline.

Proton magnetic resonance imaging in ischemic cerebrovascular disease

Proton magnetic resonance imaging (MRI) using a 0.6- or 1.5-Tesla superconductive magnet was compared with high-resolution computed tomography (CT) in 60 patients with transient ischemic attacks (TIAs) or brain infarction. MRI showed focal parenchymal changes in 84% of patients with TIAs, whereas CT showed similar changes in 42%. The sensitivity of MRI was also greater in patients with infarcts, but the difference between CT and MRI was not as great. Infarcts were usually better delineated by MRI regardless of location. However, MRI failed to reveal cortical infarcts that were clearly seen on contrast-enhanced CT scans and was unable to clearly distinguish subacute from chronic hemorrhagic infarcts. MRI changes were best detected with T2-weighted images and usually appeared as multiple areas of increased signal intensity in the subcortical and periventricular white matter. MRI changes often could not be correlated with the clinical history and neurological findings; identical changes have been seen in patients with no history of cerebrovascular disease.

Leptomeningeal metastasis from supratentorial malignant gliomas

The clinical and diagnostic findings in 13 patients with leptomeningeal metastasis from supratentorial malignant gliomas are reported. Criteria for inclusion in this study were positive myelographic examination, positive cerebrospinal fluid cytology on two or more samples, or evidence of leptomeningeal seeding at autopsy. Eight patients had premortem symptoms of leptomeningeal metastasis, with the diagnosis confirmed during life in 5 patients. Average survival after the onset of symptoms was 3 months (range, 1 to 5 months). Comparison of the autopsied group with 10 concurrent autopsied patients without leptomeningeal gliomatosis did not reveal any significant differences in age, but leptomeningeal gliomatosis was more prevalent in patients with longer postoperative survival. Leptomeningeal involvement at autopsy was more extensive in symptomatic patients. Cerebrospinal fluid examination often gave nondiagnostic or nonspecific results. Computed tomography of the brain showed evidence of ventriculomegaly, periventricular contrast enhancement, or multifocal tumor involvement in every case. Iophendylate myelography was the most reliable diagnostic tool and established the diagnosis whenever performed. The natural history and clinical significance of leptomeningeal metastasis from supratentorial malignant gliomas are discussed.

Focal parenchymal lesions in transient ischemic attacks: correlation of computed tomography and magnetic resonance imaging

Twenty-two patients with the clinical diagnosis of transient ischemic attacks were prospectively evaluated by computed tomography (CT) and proton magnetic resonance imaging (MRI). Nineteen patients also underwent cerebral angiography. The MRI studies were performed with a prototype super-conductive magnet using a 0.6 Tesla or a 1.5 Tesla magnetic field. Two pulse sequence techniques were used resulting in T1 and T2 weighted images. All studies were interpreted descriptively by a single neuroradiologist in a blinded fashion, with special attention to focal parenchymal abnormalities. Patients with previously documented clinical strokes or reversible ischemic neurologic deficits lasting more than 24 hours were excluded. The CT scans revealed focal areas of abnormalities in 7 of 22 patients (32%), while the MRI scans showed focal changes in 17 patients (77%). All the CT lesions were clearly visualized on MRI. The MRI changes were better seen on T2 weighted images as areas of increased signal intensity. There was a marked preponderance of deep hemispheric lesions on both CT and MRI studies. Focal parenchymal abnormalities were not limited to the symptomatic vascular territory. We conclude that MRI reveals focal parenchymal changes in the majority of patients with transient ischemic attacks and is more sensitive than late generation CT scans. However, specificity appears to be poor, and may limit clinical usefulness. While the significance of the MRI "lesions" remains speculative, they may represent markers of chronic cerebrovascular disease in these patients.

Nocardial osteomyelitis of the spine with epidural spinal cord compression--a case report

A 53-year-old man presented with complaints of back pain and weakness in his lower extremities. Physical examination demonstrated a thoracic myelopathy with a sensory level at T-4. The diagnostic work-up revealed vertebral osteomyelitis of the thoracic spine with epidural compression at T-2-T-4 causing a nearly complete block on myelography. A decompressive laminectomy and debridement were performed, followed by anterior spinal fusion. Nocardia asteroides was cultured from the epidural space. The patient was concurrently treated with sulfonamides. No underlying malignancy or immunosuppression could be demonstrated, but a primary pulmonary nocardial infection was suspected. A satisfactory recovery was accomplished. Only four other cases of nocardial osteomyelitis of the spine have been reported in the literature. These are discussed, and possible mechanisms are proposed for the pathophysiology of this rare manifestation. Current recommendations on the specimen processing, diagnosis, and therapy of nocardial infections are briefly reviewed.

Changes in intracranial stenotic lesions after extracranial-intracranial bypass surgery

The natural history of intracranial arterial stenosis is not well understood. The lesions are pathologically quite diverse, and are subject to resolution, progression, or occlusion. The authors undertook an investigation to examine what effects, if any, extracranial-intracranial (EC-IC) bypass surgery had on the evolution of intracranial arterial stenosis in 18 patients undergoing EC-IC bypass procedures for ipsilateral hemispheric ischemia. There was inaccessible internal carotid artery stenosis in 14 patients, and middle cerebral artery stenosis in four patients. Early (within 2 weeks) and late (at 6 months) postoperative angiography was performed in all patients. During the period of the study, there was a significant change in the arterial stenosis in 50% of the patients (nine of 18). The stenotic artery became occluded in four patients while the grafts were widely patent. The occlusion occurred within a few days after the operation in three of the four cases, and was accompanied by an ischemic stroke in these patients. There was improvement or resolution of the stenotic lesion in five patients; the graft became occluded in two of these cases and was patent but showed poor cortical artery filling in the other three. All these patients remained asymptomatic and the change was detected on routine late postoperative angiograms. It is concluded that arterial stenoses should not be viewed as static or inflexible lesions, and that EC-IC bypass procedures can modify the hemodynamic parameters across stenotic lesions, predisposing them to improvement or worsening. This, in turn, may affect bypass patency. Such hemodynamic interactions are accompanied by ischemic symptoms in some patients, and contribute to the relatively higher morbidity associated with EC-IC bypass surgery in the setting of arterial stenosis.

Modification of focal cerebral ischemia by prostacyclin and indomethacin

✓ The object of this investigation was to study the effects of prostacyclin (PGI2), with and without indomethacin, upon the evolution of cerebral infarction in the cat. Thirty-five fasted adult cats, lightly anesthetized with nitrous oxide, underwent right middle cerebral artery (MCA) occlusion. Eleven cats received an intracarotid infusion of 10 mg/ml PGI2 in buffered saline, pH 10.5, at a rate of 0.01 ml/kg/min (100 ng/kg/min), 10 cats received the same infusion plus a single dose of intravenous indomethacin (4 mg/kg) in buffered saline, and 11 cats received intracarotid buffered saline, pH 10.5, at a rate of 0.01 ml/kg/min, without therapeutic agents. Treatment with PGI2 was started upon MCA occlusion and continued for 6 hours, whereas indomethacin was given immediately prior to occlusion. Thirty minutes before perfusion, the animals were given fluorescein and Evans blue by intravenous injection. The cats were perfusion-fixed in vivo with carbon and buffered formalin 6 hours after MCA occlusion. Another five cats received tritium-labeled PGI2, and peripheral venous samples were collected and assayed for PGI2 and its alpha-keto metabolite. Mean arterial pressure was stable in treated animals during 6 hours of MCA occlusion, while untreated cats had significant (α = 0.05) progressive hypertension during that period. The regional cerebral blood flow (rCBF), measured by the intracarotid xenon-133 clearance method, decreased markedly in all animals immediately upon MCA occlusion. Untreated animals had a significant progressive improvement in rCBF during the occlusion period (α = 0.005), while treated animals had no such improvement. Quantitative electroencephalographic changes, gross edema, areas of fluorescein extravasation, and microscopic morphology (edema and infarct size) were not significantly different in the three groups. Prostacyclin appeared to reduce the extravasation of Evans blue dye. Systemic PGI2 levels were significant despite intracarotid administration. The authors conclude that 1) intracarotid PGI2 has a protective effect against the breakdown of the blood-brain barrier to protein-bound dyes seen in ischemic edema; 2) the systemic hemodynamic influence of PGI2, in the presence of impaired autoregulation, may compromise rCBF in the ischemic zone and offset any direct beneficial effects; and 3) indomethacin fails to modify the effects of PGI2.

Treatment of acute focal cerebral ischemia with prostacyclin

The object of this investigation was to study the effects of prostacyclin (PGI2) upon the evolution of acute focal cerebral ischemia in the cat. Twenty-five fasted adult cats, lightly anesthetized with nitrous oxide, underwent right middle cerebral artery (MCA) occlusion. Eleven cats received an intracarotid infusion of PGI2 in buffered saline pH 10.5 (100 ng/kg/min at 0.01 ml/kg/min), and 11 cats received intracarotid buffered saline pH 10.5 (0.01 ml/kg/min) without therapeutic agents. Treatment with PGI2 was started upon MCA occlusion and continued for 6 hours. Thirty minutes prior to perfusion, the animals were given fluorescein and Evans blue by intravenous injection. The cats were perfused-fixed in vivo with carbon and buffered formalin 6 hours after MCA occlusion. Another 3 cats received tritium labeled intracarotid PGI2, and peripheral venous samples were collected and assayed for PGI2 plasma levels. Mean arterial pressure was stable in PGI2 treated animals during 6 hours of MCA occlusion, while untreated cats had significant progressive hypertension during that period. The rCBF (measured by the intracarotid 133Xe method) decreased markedly in all animals immediately upon MCA occlusion. However, untreated animals had a significant progressive improvement in rCBF during the occlusion period, while PGI2 treated animals had no such improvement. Quantitative EEG changes, gross edema, areas of fluorescein extravasation, patterns of carbon perfusion, and infarct size were not significantly different in the two groups. While most untreated animals had marked Evans blue extravasation after 6 hours of MCA occlusion, most PGI2 treated animals had no such extravasation, indicating some protection of the blood-brain barrier in these animals.

Correlation of clinical and angiographic findings in brain ischemia with regional cerebral blood flow measured by the xenon inhalation technique

Eighty-eight patients with brain ischemia underwent cerebral angiography and measurement of regional cerebral blood flow (rCBF) after 133Xe inhalation. A fast compartment flow rate and an initial slope index were computed for each detector and for each hemisphere. The clinical presentation, angiographic findings, and rCBF results were then examined for significant correlations. Patients with hemispheric infarction most frequently showed bilateral diffusely decreased rCBF. In patients with transient ischemic attacks, no specific pattern emerged. Patients with unilateral internal carotid artery occlusion frequently hd bilateral diffusely decreased rCBF. Patients with severe internal carotid artery stenosis were more likely to show decreased rCBF than were patients with mild or moderate stenosis. The initial slope index seemed to be a more sensitive indicator of brain ischemia than the fast compartment flow rate. The possible pathophysiological significance and relationship to patient management of the various rCBF patterns are discussed.

Intravenous digital subtraction angiography: an index of collateral cerebral blood flow in internal carotid artery occlusion

The objective of this investigation was to correlate Xenon-133 inhalation rCBF measurements with the pattern of cortical arterial filling on intravenous DSA in 18 patients with unilateral internal carotid artery occlusion. Of 9 patients showing symmetrical filling of hemispheric cortical arteries, none showed an inter-hemispheric difference in rCBF ( delta Fg) greater than 10ml/100gm/min. Of 9 patients showing delayed cortical opacification ipsilateral to the internal artery occlusion, 3 showed a delta Fg greater than 10ml/100gm/min, 3 showed a delta Fg in the 7-10ml/100gm/min range, and 3 had a delta Fg less than 7ml/100gm/min. All patients with asymmetric abnormalities in the rCBF profile had the delayed pattern of cortical filling on DSA. The presence of symmetrical hemispheric opacification of cortical arteries on DSA indicates adequate interhemispheric redistribution of rCBF and patent inter-hemispheric collateral channels, but not necessarily normal cerebral blood flow. The presence of delayed cortical arterial opacification on the side of internal carotid artery occlusion does not necessarily imply significant inter-hemispheric rCBF differences, nor does it rule out a normal rCBF. The presence of bilateral reduction of rCBF and symmetrical cortical artery filling on DSA may represent an "interhemispheric steal".