Virtual histology intravascular ultrasound in carotid interventions.

PURPOSE: To report early clinical experience with virtual histology intravascular ultrasound (VH IVUS) in carotid endoluminal repair. TECHNIQUE: A 2.9-F, 20-MHz catheter that utilizes computer software to demonstrate the histological components of arteriosclerotic plaque was evaluated during carotid angioplasty and stenting. VH IVUS images were created following a pullback through the carotid stenosis and produced a color-coded map of the different histological constituents of the disease (dark green: fibrous, yellow/green: fibrofatty, white: calcified, and red: necrotic lipid core plaque). CONCLUSION: VH IVUS produces a color-coded map of the different histological components of artery plaque. It has the potential to predict how the plaque is likely to behave at the moment of endoluminal treatment.     

Two-year randomized controlled trial of vitamin K1 (phylloquinone) and vitamin D3 plus calcium on the bone health of older women.

Dietary supplementation with vitamin K(1), with vitamin D(3) and calcium or their combination, was examined in healthy older women during a 2-year, double-blind, placebo-controlled trial. Combined vitamin K with vitamin D plus calcium was associated with a modest but significant increase in BMC at the ultradistal radius but not at other sites in the hip or radius. INTRODUCTION: The putative beneficial role of high dietary vitamin K(1) (phylloquinone) on BMD and the possibility of interactive benefits with vitamin D were studied in a 2-year double-blind, placebo-controlled trial in healthy Scottish women > or =60 years of age. MATERIALS AND METHODS: Healthy, nonosteoporotic women (n = 244) were randomized to receive either (1) placebo, (2) 200 microg/day vitamin K(1), (3) 10 microg (400 IU) vitamin D(3) plus 1000 mg calcium/day, or (4) combined vitamins K(1) and D(3) plus calcium. Baseline and 6-month measurements included DXA bone mineral scans of the hip and wrist, markers of bone turnover, and vitamin status. Supplementation effects were tested using multivariate general linear modeling, with full adjustment for baseline and potential confounding variables. RESULTS: Significant bone mineral loss was seen only at the mid-distal radius but with no significant difference between groups. However, women who took combined vitamin K and vitamin D plus calcium showed a significant and sustained increase in both BMD and BMC at the site of the ultradistal radius. Serum status indicators responded significantly to respective supplementation with vitamins K and D. Over 2 years, serum vitamin K(1) increased by 157% (p < 0.001), the percentage of undercarboxylated osteocalcin (%GluOC) decreased by 51% (p < 0.001), serum 25-hydroxyvitamin D [25(OH)D] increased by 17% (p < 0.001), and PTH decreased by 11% (p = 0.049). CONCLUSIONS: These results provide evidence of a modest synergy in healthy older women from nutritionally relevant intakes of vitamin K(1) together with supplements of calcium plus moderate vitamin D(3) to enhance BMC at the ultradistal radius, a site consisting of principally trabecular bone. The substantial increase in gamma-carboxylation of osteocalcin by vitamin K may have long-term benefits and is potentially achievable by increased dietary intakes of vitamin K rather than by supplementation.     

Impact of a region-wide approach to improving systems for heart attack care: the West Midlands thrombolysis project.

OBJECTIVE: To describe changes in delay to administration of thrombolytic therapy associated with a region-wide audit. DESIGN: Observational study of patients admitted with suspected myocardial infarction (MI) based on continuous audit. SUBJECTS: 18877 patients admitted to 23 hospitals with suspected MI between April 1995 and March 1998. RESULTS: Of 11232 patients with a discharge diagnosis of definite MI, 8802 (46.6%) received thrombolytic therapy during hospitalisation, with 5155 patients eligible for treatment on admission to hospital on the basis of established indications. Call-to-needle time for those eligible for treatment on admission fell from median 105 min in the first year of the project to 85 min in year 3 (P<0.001), and door-to-needle time fell from 45 to 35 min (P<0.001). Forty percent of eligible patients were treated within the then current national standard of 90 min from time of call for help, with nearly 49% in the final year and 20% being treated within the new national standard of 60 min, by the third year. CONCLUSION: The proportion of eligible patients receiving thrombolysis within 1 h of the call for help doubled during the 3-year project but the majority of patients still wait longer than 60-min 'call-to-needle'. New systems to reduce delays to administration of thrombolysis to within 60 min of call for help are required, including consideration of pre-hospital treatment.     

Radiopacity of dental materials using a digital X-ray system.

OBJECTIVES: Radiopacity is a desirable property for most intra-oral materials. There are established ISO and ANSI/ADA protocols for determining radiopacity using film-based radiography. However, these methods are not always followed by researchers. This study aims to adapt those procedures by using digital radiography, a simplified stepwedge, and examine the effects of target distance and exposure time choice. METHODS: One millimetre thick samples of three dental materials were prepared by placing the materials into a 1.00 mm thick washer sandwiched between two glass slides. The samples were digitally radiographed alongside a stepwedge of aluminum alloy 1100 with an X-ray unit at 70 kVp using five different target distance/exposure time combinations. For each combination, the grey scale values of various thicknesses of the stepwedge were converted into absorbencies and plotted against their thickness. These plots were then linearly regressed in order to correlate absorbance with a thickness of aluminum for each target distance/exposure time combination. The absorbencies of each sample were then converted into radiopacities using these correlations. RESULTS: The correlations between the absorbance of the stepwedge and its thickness were highly linear. This linearity allows the correlation to be accurately deduced from fewer data points than required by the ISO and ANSI/ADA protocols. Varying exposure time did not significantly affect the mean radiopacity measured at a target distance of 30 cm. Varying the target distance did not significantly affect the measured radiopacity as long as the samples were properly exposed. SIGNIFICANCE: A simplified, consistent digital method for determining radiopacity is presented.     

Bazett and Fridericia QT correction formulas interfere with measurement of drug-induced changes in QT interval.

BACKGROUND: The QT interval on the ECG is prolonged by more than 50 marketed drugs, an effect that has been associated with syncope and/or sudden cardiac death due to an arrhythmia. Because changes in heart rate also change the QT interval, it has become standard practice to use a correction formula, such as the Bazett formula, to normalize the QT interval to a heart rate of 60 bpm, that is, the rate-corrected QT or QTc. Numerous other formulas have been devised to make this correction, including the Fridericia, Hodges, and Framingham formulas. OBJECTIVES: The purpose of this study was to investigate how the Bazett formula and three other formulas influence assessment of the QT-prolonging effect of the potassium channel-blocking drug ibutilide. METHODS: Using a standardized physical activity protocol, the QT interval was assessed over a broad range of heart rates before and after an infusion of ibutilide (4.75 microg/kg) that produced a stable 15- to 20-ms QT prolongation in consenting normal subjects (9 men and 9 women). The QT interval was measured digitally over a range of heart rates from 60 to 120 bpm, and then four correction formulas (Bazett, Fridericia, Framingham, or Hodges) were applied. The uncorrected change in QT interval due to ibutilide was compared with the change using each of the formulas by repeated measures analysis of variance. RESULTS: At heart rates from 60 to 120 bpm, the Bazett and Fridericia correction formulas overestimated the change in QT in both men and women (P <.001). However, the Framingham and Hodges formulas did not alter the accuracy of the assessment of QT interval change. CONCLUSION: Rate correction of QT intervals using the standard Bazett and Fridericia formulas can introduce significant errors in the assessment of drug effects on the QT interval. This has implications for the clinical assessment of drug effects and for the safety assessment of new drugs under development.     

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Functional Symptoms and Somatoform Disorders in Children and Adolescents: The Role of Standardised Measures in Assessment

Functional or unexplained medical symptoms (physical symptoms that are not adequately explained by organic factors and where a major role for psychological factors is assumed) are common amongst children in the general population but can also be an expression of somatisation and somatoform disorders. Co-morbid psychopathology is common. We describe measures mostly used in research into problems related to somatisation in children and adolescents that may be helpful to clinical researchers. Some address the nature and severity of physical symptoms, others document illness attitudes, beliefs and functional impairment, and a third group assesses emotional symptoms. Questionnaires can be helpful for clinicians in quantifying (i) the nature and severity of somatic symptoms and associated functional impairment, (ii) contributory health attitudes and illness beliefs and (iii) co-morbid or primary anxiety and depressive disorders. Together with pain and activity diaries and careful documentation of school attendance, these measures may also be helpful in monitoring treatment response.     

Prospective Study of the Incidence of Transient Radicular Irritation in Patients Undergoing Spinal Anesthesia

Background: There is considerable controversy regarding the role of subarachnoid 5% hyperbaric lidocaine in the syndrome transient radicular irritation (TRI). This randomized, double-blinded, prospective study was designed to determine the incidence of TRI and identify factors possibly contributing to its development.

Methods: One hundred fifty-nine ASA physical status 1 or 2 patients undergoing outpatient knee arthroscopy or unilateral inguinal hernia repair were prospectively randomized to receive spinal anesthesia with 5% hyperbaric lidocaine with epinephrine (60 mg with 0.2 mg epinephrine for arthroscopy or 75 mg with 0.2 mg epinephrine for hernia repair), 2% isobaric lidocaine without epinephrine (60 mg for arthroscopy or 75 mg for hernia repair), or 0.75% hyperbaric bupivacaine without epinephrine (7.5 mg for arthroscopy or 9.0 mg for hernia repair) in a double-blinded fashion. On the 3rd postoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications including TRI, defined as back pain with radiation down one or both buttocks or legs occurring within 24 h after surgery. Postoperatively, time from injection to block resolution, ambulation, voiding, and ready for discharge were recorded by a postanesthesia care unit nurse blinded to the group assignment.

Results: The incidence of TRI was greater in patients receiving lidocaine than in those receiving bupivacaine (16% vs. 0%; P = 0.003). There was no difference in the incidence of TRI between the patients receiving 59% hyperbaric lidocaine with epinephrine and those receiving 2% isobaric lidocaine without epinephrine (16% vs. 16%; P = 0.98). The incidence of TRI was greater in patients undergoing arthroscopy than in those undergoing hernia repair (13% vs. 5%; P = 0.04). There was no difference in discharge times in patients receiving bupivacaine versus those receiving hyperbaric lidocaine with epinephrine (292 vs. 322 min; P = 0.61).     

Cerebral Emboli during Cardiac Surgery in Children

Background: Microemboli occur commonly during cardiac surgery in adults, and, when present, increase the risk of neuropsychological deficits. Their incidence and significance during correction of congenital heart disease is unknown. The authors hypothesized that microemboli would occur before bypass with right-to-left cardiac shunts and would also occur in large numbers when the aortic crossclamp was released in children during repair of congenital heart defects.

Methods: In 25 children studied with carotid artery Doppler, embolic signals were counted and timed in relation to 13 intraoperative events. Patients were classified as either at high risk (obligate right-to-left shunt or uncorrected transposition of the great arteries) or at low risk (net left-to-right shunt or simple obstructive lesions) for paradoxical (venous to arterial) emboli.

Results: The median number of emboli detected was 122 (range, 2-2,664). Forty-two percent of all emboli were detected within 3 min of release of the aortic crossclamp. The high-risk group had significantly more emboli (median, 66; range, 0-116) during the time interval before cardiopulmonary bypass than did the low-risk group (median, 8; range, 0-73), with P < 0.01. There was no significant difference between the high-and low-risk groups in the total number of emboli detected. There was no apparent association between number of emboli and gross neurologic deficits.