Biomedical subjects

K B Schechtman

Publications and source records attributed to K B Schechtman.

At least 37 records · Page 2Linked to original sources

PubMed2000

Role of tissue factor-mediated coagulation in ischemia/ reperfusion-induced injury of Langendorf-perfused rabbit hearts.

BACKGROUND: Production of oxygen free radicals, and activation of neutrophils and plasma complement contribute to myocardial reperfusion injury, but the role of coagulation has not been assessed. OBJECTIVE: To characterize tissue-factor-mediated generation of thrombin and its association with tissue injury during reperfusion from normothermic ischemia of isolated, Langendorf-perfused rabbit hearts. METHODS: Activation of coagulation was assessed by addition of 12% rabbit plasma and human fibrinogen to Krebs-Henseleit-buffer perfusate with measurement of levels of human fibrinopeptide A (hFPA) in the heart effluent as an index of thrombin-mediated formation of fibrin. RESULTS: Concentrations of hFPA in the effluent were minimal during non-ischemic perfusion (5 +/- 5 ng/ml, n=6) and during 50 min of ischemia (13 +/- 3 ng/ml, n=6), but increased markedly during the first 20 min of reperfusion (to 41 +/- 29 ng/ml, P=0.03 versus before reperfusion). Addition to the perfusate of 10 microg/ml recombinant human tissue-factor-pathway inhibitor, the physiologic inhibitor of tissue-factor-mediated coagulation, abolished increases in the level of hFPA after reperfusion. However, indexes of myocardial injury manifested during reperfusion, including decrease in recovery of left ventricular pressure developed, increase in left ventricular end-diastolic pressure, and increase in activity of creatine kinase in the heart effluent, were not improved by anticoagulation with recombinant human tissue-factor-pathway inhibitor. CONCLUSION: Our results do not support the hypothesis that coagulation plays a major role in ischemia/reperfusion injury of Langendorf-perfused rabbit hearts.

Animals↗

PubMed2000

Effects of diminished expression of connexin43 on gap junction number and size in ventricular myocardium.

Gap junction number and size vary widely in cardiac tissues with disparate conduction properties. Little is known about how tissue-specific patterns of intercellular junctions are established and regulated. To elucidate the relationship between gap junction channel protein expression and the structure of gap junctions, we analyzed Cx43 +/- mice, which have a genetic deficiency in expression of the major ventricular gap junction protein, connexin43 (Cx43). Quantitative confocal immunofluorescence microscopy revealed that diminished Cx43 signal in Cx43 +/- mice was due almost entirely to a reduction in the number of individual gap junctions (226 +/- 52 vs. 150 +/- 32 individual gap junctions/field in Cx43 +/+ and +/- ventricles, respectively; P < 0.05). The mean size of an individual gap junction was the same in both groups. Immunofluorescence results were confirmed with electron microscopic morphometry. Thus when connexin expression is diminished, ventricular myocytes become interconnected by a reduced number of large, normally sized gap junctions, rather than a normal number of smaller junctions. Maintenance of large gap junctions may be an adaptive response supporting safe ventricular conduction.

Animals↗

PubMed1999

Risk factors for early or delayed stroke after cardiac surgery.

BACKGROUND: Stroke after cardiac surgery is a devastating complication that leads to excess mortality and health resource utilization. The purpose of this study was to identify risk factors for perioperative stroke, including strokes detected early after cardiac surgery or postoperatively. METHODS AND RESULTS: Data were obtained from 2972 patients undergoing coronary artery bypass graft and/or valve surgery. Patients >/=65 years old and those with a history of symptomatic neurological disease underwent preoperative carotid artery ultrasound scanning. Intraoperative epiaortic ultrasound to assess for ascending aorta atherosclerosis was performed in all patients. New strokes were considered as a single end point and were categorized with respect to whether they were detected immediately after surgery (early stroke) or after an initial, uneventful neurological recovery from surgery (delayed stroke). Strokes occurred in 48 patients (1.6%); 31 (65%) were delayed strokes. By multivariate analysis, prior neurological event, aortic atherosclerosis, and duration of cardiopulmonary bypass were independently associated with early stroke, whereas predictors of delayed stroke were prior neurological event, diabetes, aortic atherosclerosis, and the combined end points of low cardiac output and atrial fibrillation. Female sex was associated with a 6.9-fold increased risk of early stroke and a 1.7-fold increased risk of delayed stroke. In-hospital mortality of patients with early (41%) and delayed (13%) strokes was higher than that of other patients (3%, P=0.0001). CONCLUSIONS: Most strokes after cardiac surgery occurred after initial uneventful recovery from surgery. Women were at higher risk to suffer early and delayed perioperative strokes. Atrial fibrillation had no impact on postoperative stroke rate unless it was accompanied by low cardiac output syndrome.

Aged↗

PubMed1999

Atherosclerosis of the ascending aorta is a predictor of renal dysfunction after cardiac operations.

OBJECTIVES: Renal dysfunction occurring after cardiac operations has been attributed to various factors, but the importance of an atherosclerotic thoracic aorta has not been previously evaluated. The purpose of this study was to identify predictors of postoperative renal dysfunction (50% or more increase from preoperative values) and to evaluate the importance of atherosclerosis of the ascending aorta as a predictor of this complication. METHODS: Nine hundred seventy-eight consecutive patients, 50 years of age and older with normal preoperative renal function (serum creatinine level of 1.5 mg/dL or less), who were scheduled to undergo cardiac surgery were prospectively evaluated. Atherosclerosis of the ascending aorta was assessed during the operation (with epiaortic ultrasound), and patients were divided into 3 groups according to its severity (normal-to-mild, moderate, and severe). RESULTS: Univariate predictors of renal dysfunction at postoperative day 1 were atherosclerosis of the ascending aorta (P <. 045) and postoperative low cardiac output (P =.05); at postoperative day 6 they were atherosclerosis of the ascending aorta (P <.0001), postoperative low cardiac output (P <.0001), advanced age (P =.001), decreased preoperative left ventricular function (P =.01), and female gender (P =.03). Multivariate analysis showed that atherosclerosis of the ascending aorta (odds ratio, 3.06; P =.04) was the only independent predictor of postoperative renal dysfunction at day 1 and that postoperative low cardiac output (odds ratio, 4.83; P <.0001), atherosclerosis of the ascending aorta (odds ratio, 2.13; P =.0006), and preoperative left ventricular dysfunction (odds ratio, 1.48; P =.028) were independent predictors of postoperative renal dysfunction at day 6. CONCLUSIONS: An atherosclerotic ascending aorta is an important predictor of postoperative renal dysfunction, possibly because atheroembolism to the kidneys occurs in the perioperative period (ie, during surgical manipulation of an atherosclerotic aorta) or because the diseased aorta may be a marker of widespread atherosclerotic disease that may predispose to perioperative renal dysfunction.

Aged↗

PubMed1999

Atherosclerosis of the ascending aorta is an independent predictor of long-term neurologic events and mortality.

OBJECTIVES: This study was undertaken to determine whether atherosclerosis of the ascending aorta is a predictor of long-term neurologic events and mortality. BACKGROUND: Atherosclerosis of the thoracic aorta has been recently considered a significant predictor of neurologic events and peripheral embolism, but not of long-term mortality. METHODS: Long-term follow-up (a total of 5,859 person-years) was conducted of 1,957 consecutive patients > or =50 years old who underwent cardiac surgery. Atherosclerosis of the ascending aorta was assessed intraoperatively (epiaortic ultrasound) and patients were divided into four groups according to severity (normal, mild, moderate or severe). Carotid artery disease was evaluated (carotid ultrasound) in 1,467 (75%) patients. Cox proportional-hazards regression analysis was performed to assess the independent effect of predictors on neurologic events and mortality. RESULTS: A total of 491 events occurred in 472 patients (neurologic events 92, all-cause mortality 399). Independent predictors of long-term neurologic events were: hypertension (p = 0.009), ascending aorta atherosclerosis (p = 0.011) and diabetes mellitus (p = 0.015). The independent predictors of mortality were advanced age (p < 0.0001), left ventricular dysfunction (p < 0.0001), ascending aorta atherosclerosis (p < 0.0001), hypertension (p = 0.0001) and diabetes mellitus (p = 0.0002). There was >1.5-fold increase in the incidence of both neurologic events and mortality as the severity of atherosclerosis increased from normal-mild to moderate, and a greater than threefold increase in the incidence of both as the severity of atherosclerosis increased from normal-mild to severe. CONCLUSIONS: Atherosclerosis of the ascending aorta is an independent predictor of long-term neurologic events and mortality. These results provide additional evidence that in addition to being a direct cause of cerebral atheroembolism, an atherosclerotic ascending aorta may be a marker of generalized atherosclerosis and thus of increased morbidity and mortality.

Aged↗

PubMed1999

Improved echocardiographic delineation of left ventricular thrombus with the use of intravenous second-generation contrast image enhancement.

Transthoracic echocardiography is the most widely used diagnostic test for left ventricular (LV) thrombus, which must be distinguished from other intraventricular structures and image artifacts. To determine whether second-generation intravenous echocardiographic contrast agents provide better delineation of LV thrombus, we reviewed the results of 2-dimensional echocardiographic studies that were performed in 409 patients over a 1-year period to detect LV thrombus. Studies of 190 (46%) patients were interpreted as nondiagnostic for this purpose, of which 48 patients underwent an additional study after intravenous injection of 0.5 to 2 mL of human albumin microspheres within 1 to 4 days. In 43 (90%) of these 48 patients the contrast-enhanced study was definitive and diagnostic for either the presence or absence of an LV thrombus (P <.0001). Of the initial total of 409 patients, 81 had been studied at the bedside in intensive care units. The bedside studies were nondiagnostic for LV thrombus in 51 (63%) of these 81 patients. Of these 51 patients, 14 underwent additional imaging with contrast enhancement, and the contrast-enhanced images became diagnostic (P =. 004) in 11 (79%) of them. Thus intravenous contrast image enhancement improves the diagnostic yield of echocardiography in patients in whom initial images are nondiagnostic for LV thrombus.

Albumins↗

PubMed1999

Effects of age and gender on the cardiovascular responses to isoproterenol.

We studied the effects of age and gender on cardiovascular responses to beta-adrenergic stimulation with the use of two-dimensional echocardiography in 16 young (aged 20-31) and 20 older (aged 60-75) healthy individuals. Following administration of atropine, each subject was given an infusion of isoproterenol at incremental doses from 0.010 to 0.030 microgram kg-1 min-1. The slopes of the fractional shortening-end-systolic wall stress (FS-sigma es) relationships were steeper in the young men (-0.87 +/- 0.28, n = 8) compared to the older men (-0.41 +/- 0.13, n = 10), and in the young women (-0.55 +/- 0.14, n = 8) compared to the older women (-0.38 +/- 0.13, n = 10). Furthermore, the magnitude of the age-associated differences in these slopes was larger in the men (old vs young) than in the women (old vs young) which, in the absence of changes in preload, suggests a greater decline in the contractile response to isoproterenol with advancing age in men compared to women. Furthermore, the men exhibited a greater attenuation of chronotropic response to isoproterenol than did the women. These observations suggest that gender plays a significant role in the age-associated decline in inotropic and chronotropic responses to beta-adrenergic stimulation, with men exhibiting a greater decline with aging than women.

Adrenergic beta-Agonists↗

PubMed1999

A comparative model: reaction time performance in sleep-disordered breathing versus alcohol-impaired controls.

OBJECTIVES/HYPOTHESIS: Patients with sleep-disordered breathing have reaction time deficits that may lead to catastrophic accidents and loss of life. Although safety guidelines do not exist for unsafe levels of sleepiness, they have been established for unsafe levels of alcohol consumption. Since reaction time performance is altered in both, we prospectively used seven measures of reaction time performance as a comparative model in alcohol-challenged normal subjects with corresponding measures in subjects with sleep-disordered breathing. STUDY DESIGN: Institutional Review Board-approved, nonrandomized prospective controlled study. METHODS: Eighty healthy volunteers (29.1+/-7.5 y of age, 56.3% female subjects) performed four reaction time trials using a psychomotor test at baseline and at three subsequent rising alcohol-influenced time points. The same test without alcohol was given to 113 subjects (47.2+/-10.8 y of age, 19.3% female subjects) with mild to moderate sleep-disordered breathing. RESULTS: Mean blood alcohol concentrations (BACs) in the alcohol-influenced subjects at baseline and three trials were 0, 0.057, 0.080, and 0.083 g/dL. The sleep-disordered subjects had mean respiratory disturbance indices of 29.2 events per hour of sleep. On all seven reaction time measures, their performance was worse than that of the alcohol subjects when BACs were 0.057 g/dL. For three of the measures, the sleep-disordered subjects performed as poorly as or worse than the alcohol subjects when alcohol levels were 0.080 g/dL. These results could not be explained by sex or age differences. CONCLUSION: The data demonstrate that sleep-disordered subjects in this study (with a mean age of 47 y) with mild to moderate sleep-disordered breathing had worse test reaction time performance parameters than healthy, nonsleepy subjects (with a mean age of 29 y) whose BAC is illegally high for driving a commercial motor vehicle in California. This comparative model points out the potential risks of daytime sleepiness in those with sleep-disordered breathing relative to a culturally accepted standard of impairment.

Adult↗

PubMed1999

Obstacles to early discharge after cardiac surgery.

CONTEXT: Cardiovascular disease and cardiac surgery, in particular, are associated with a large expenditure of healthcare resources. Identifying the factors that affect length of stay for patients hospitalized for cardiac surgery and ways to safely and effectively shorten stays could have significant impact on healthcare costs. OBJECTIVE: To identify obstacles to and the effects of early discharge on outcome after cardiac surgery. STUDY DESIGN: A prospective approach using a protocol consisting of modifying anesthesia, limiting the use of postoperative narcotics, early extubation, and early mobilization, with a goal of discharge at < 5 days. PATIENTS AND METHODS: The study group consisted of 422 consecutive patients (age range 15-89 years, 65% males): coronary artery bypass graft (CABG) (n = 290), valve procedures (n = 54), and CABG + valve procedures (n = 78). The discharge criteria included hemodynamic stability, normal bowel function, independence in activities of daily living, absence of fever, and no incision problems. RESULTS: Predictors of prolonged postoperative stay were prolonged intensive care unit stay (P < 0.0001), postoperative atrial fibrillation (P = 0.0006), preoperative congestive heart failure (P = 0.002), combined CABG and valve procedure (P = 0.005), prolonged ventilator support (P = 0.01), increasing age (P = 0.012), history of peripheral vascular disease (P = 0.02), and female gender (P = 0.025). The 30-day readmission rate for the early discharge group was 7.8% vs 16.2% for the late discharge group (P = 0.01). The mortality rate for the entire group was 3.3%.

Adolescent↗

PubMed1999

Corneal scarring in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: baseline prevalence and repeatability of detection.

PURPOSE: The multicenter Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study is a prospective, observational study of 1,209 keratoconus patients. We report on the prevalence of corneal scarring in these patients. We also report on the test-retest repeatability of corneal scar documentation at the slit-lamp biomicroscope by trained clinicians and by masked photograph readers and on the scarring-status agreement at baseline between clinicians and photograph readers. METHODS: Clinicians and masked photograph readers graded each cornea as to scarring status. Patients were examined by clinicians, and their corneas were photographed at baseline (2,297 nongrafted eyes of 1,209 patients) and at a repeated visit (258 nongrafted eyes of 138 patients). These photographs were evaluated by the masked readers at the CLEK Photography Reading Center (CPRC). Clinicians reported corneal scars in right eyes at baseline as "definitely not present" in 53.9%, "probably not present" in 8.4%, "probably present" in 8.2%, and "definitely present" in 29.4% of patients. A weighted kappa statistic of 0.83 (95% confidence interval from 0.78 to 0.88) indicates that agreement is excellent between baseline and repeated assessments for the presence of a corneal scar by clinicians. RESULTS: Agreement is very good between baseline and repeated photograph-reader assessments for the presence of a scar, with a weighted kappa of 0.77 (95% confidence interval, 0.72-0.82). The kappa statistic comparing photograph-reader scarring assessments with clinician results was 0.69 (95% confidence interval, 0.66-0.71). CONCLUSION: The data also suggest better agreement between clinicians and readers when Vogt's striae and corneal nerves were observed. The data also suggest better agreement when corneal staining was not observed by the photograph readers. The CLEK Study protocol for determining the presence of scars is highly repeatable.

Cicatrix↗

PubMed1998

Visual acuity repeatability in keratoconus: impact on sample size. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group.

PURPOSE: The purpose of this paper is to determine the repeatability of visual acuity measurement in keratoconus and to describe the impact of measurement repeatability on sample size. METHODS: Approximately 10% of a 1209 patient sample in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study were selected randomly for a Repeat CLEK Study Visit. Patients were tested at the 15 CLEK Participating Clinics. The test-retest sample consisted of 1 34 keratoconus patients who met the entry criteria of the CLEK Study. High and low contrast Bailey-Lovie visual acuity was measured with the patient's habitual visual correction (entrance visual acuity monocularly and binocularly), and with the best correction monocularly (either the patient's rigid contact lens and over-refraction, or with a CLEK Study trial lens and appropriate over-refraction) at two visits separated by a median of 90 days (range 22 to 268 days). RESULTS: The mean absolute differences between the number of letters correct at the two visits ranged from a low of 3.24 +/- 3.1 for entrance high contrast binocular acuity to a high of 5.48 +/- 5.1 for best corrected low contrast monocular acuity. Intraclass correlation coefficients ranged from 0.757 to 0.853. The visual acuity score was somewhat higher at the Repeat Visit than at the Baseline Visit when the examiners were different between visits. CONCLUSIONS: Given the variable vision reported by keratoconus patients, visual acuity in this sample was very repeatable. Repeatability was slightly poorer when different examiners tested visual acuity at the Baseline and Repeat Visits.

Adolescent↗

PubMed1998

Repeatability of refraction and corrected visual acuity in keratoconus. The CLEK Study Group. Collaborative Longitudinal Evaluation of Keratoconus.

PURPOSE: The purpose of the test-retest phase of the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study was to determine the repeatability of the various parts of the CLEK Study protocol. This paper presents the test-retest parameters of the refraction protocol. METHODS: We examined 138 CLEK Study-eligible patients on two occasions (median, 90 days; range, 22 to 268 days). All patients underwent subjective refraction on two occasions, and contact lens over-refractions were performed either over the patient's habitual rigid contact lenses or over a trial rigid contact lens equal in base curve to the steep keratometric reading in nonrigid contact lens wearers. RESULTS: Mean interoccasion differences +/- SD were -0.32 +/- 2.91 D and -0.17 +/- 1.39 D for subjective refraction sphere and cylinder power, respectively, and the mean absolute difference for subjective refraction cylinder axis was 18.1 +/- 20.2 degrees. The mean interoccasion difference +/- SD for high-contrast visual acuity with subjective refraction was 0.38 +/- 10.9 letters correct. Mean interoccasion differences +/- SD were -0.11 +/- 0.81 D and 0.02 +/- 0.67 D for contact lens over-refraction sphere and cylinder power, respectively, and the mean absolute difference for contact lens over-refraction cylinder axis was 11.6 +/- 9.9 degrees. The mean interoccasion difference +/- SD for visual acuity with contact lens over-refraction was 0.50 +/- 5.2 letters correct and 0.71 +/- 6.9 letters correct for high- and low-contrast visual acuity, respectively. CONCLUSIONS: The repeatability of subjective refraction in keratoconus patients is good but somewhat lower than that found in nondiseased eyes. Only 36% of our repeat measures of sphere power from subjective refraction fell within 0.50 D of each other, compared with more than 90% in studies of normal eyes.

Adult↗

PubMed1997

Comparison of adaptations to a 12-month exercise program and late outcome in patients with healed myocardial infarction and ejection fraction <45% and >50%.

To characterize the differences in adaptations to endurance exercise training and prognosis between patients with depressed and normal left ventricular (LV) function, 20 patients with coronary artery disease were studied and followed for 7 years. Patients with normal LV function had enhancement of LV systolic function, but the group with LV dysfunction did not exhibit cardiac adaptations and had more cardiac events than those with normal LV function.

Adaptation, Physiological↗

PubMed1997

Gender, self-reported depressive symptoms, and sleep disturbance among older community-dwelling persons. FICSIT group. Frailty and Injuries: Cooperative Studies of Intervention Techniques.

The purposes of this report are: (1) to investigate the association between sleep disturbances and depressive symptomatology in older adults; (2) to evaluate the degree to which gender serves to mediate this relationship; and (3) to determine whether several predefined covariates help to explain the association between sleep disturbance and depressive symptoms. This is a retrospective and cross-sectional analysis of baseline data from 485 elderly adults enrolled in three of the eight clinical sites participating in the Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT) trials. FICSIT was a linked series of randomized clinical trials which evaluated the impact of various exercise interventions on several measures of frailty in older adults. Women reported more depressive symptoms and more sleep disturbances than men. Sleep disturbances were independently associated with depressive symptoms, bodily pain, a history of falling, limited education, being married, and being female. Gender interactions suggest that, although women reported more depressive symptoms and more chronic health conditions than men, both may be more important predictors of sleep disturbance in men. By contrast, being married may be more predictive in women. Finally, the data suggest a stronger relationship between sleep disturbance and depressive symptoms in men than in women.

Activities of Daily Living↗

PubMed1996

Superiority of C-11 acetate compared with F-18 fluorodeoxyglucose in predicting myocardial functional recovery by positron emission tomography in patients with acute myocardial infarction.

In patients with chronic coronary artery disease, preservation of myocardial oxidative metabolism measured by positron emission tomography (PET) with 11C-acetate is a more accurate predictor of subsequent myocardial functional recovery than is maintenance of glucose metabolism estimated with 18F-fluorodeoxyglucose. However, whether measurements of myocardial oxidative metabolism are more accurate than measurements of glucose metabolism in predicting functional recovery in patients with recent myocardial infarction is unknown. Myocardial oxidative metabolism was measured within 10 days of infarction in 19 patients by analysis of the rate of myocardial clearance of 11C-acetate. Metabolism of glucose was assessed by analysis of the uptake of 18F-fluorodeoxyglucose. Criteria for prediction of the recovery of function based on measurements of oxidative metabolism and glucose metabolism were compared. Threshold criteria with 11C-acetate exhibited superior positive and negative predictive values (89% and 73%, respectively) compared with the criteria of 18F-fluorodeoxyglucose (65% and 57%, respectively) (p <0.025). In addition, the magnitude of functional recovery after revascularization correlated with the severity of the metabolic abnormality present initially. In patients with recent myocardial infarction, the extent of functional recovery can be predicted accurately by measurement of regional oxidative metabolism by PET with 11C-acetate, and these measurements are superior to those of 18-fluorodeoxyglucose.

Acetates↗

PubMed1996

Gender-related differences in left ventricular filling dynamics in older subjects after endurance exercise training.

The present study was designed to determine if gender affects the adaptive response to endurance exercise training of left ventricular filling dynamics in older individuals. Recently, it was shown that gender influences the cardiovascular responses to endurance exercise training in older subjects. Older men improve left ventricular systolic performance and increase maximal cardiac output in response to endurance exercise training, whereas older women do not. Twelve men (65 +/- 1 years old; mean +/- SE) and 10 women (64 +/- 1) were studied before and after 9 months of endurance exercise training. Maximal O2 uptake was determined during treadmill exercise. Left ventricular filling dynamics and ejection fraction (EF) at rest and during supine exercise were assessed by Tc-99m radionuclide ventriculography. When expressed relative to body weight, maximal O2 uptake (VO2 max) was increased by 24% (27.3 +/- 1.5 to 34.0 +/- 1.5 ml/kg/min; p < .01) in men and 27% (21.9 +/- 1.0 to 27.8 +/- 1.0 ml/kg/min; p < .01) in women in response to endurance exercise training. In men, the time-to-peak filling rate (TPFR) decreased (-19.8 +/- 6.7 ms; p < .05) during exercise at a comparable heart rate in response to training. In contrast, the change in TPFR in women (+2.7 +/- 6.0 ms) was small and insignificant. Peak filling rate (PFR) at rest and during exercise was similar before and after training in men and women. The change in left ventricular systolic reserve at a comparable heart rate from pre-to posttraining improved in men (delta EF 4 +/- 3%; p < .05), but not in women (-2 +/- 3%). The results indicate that the adaptive response of left ventricular filling dynamics to endurance exercise training is influenced by gender in older subjects. Older men show improvement in left ventricular filling dynamics, whereas older women do not.

Aged↗

PubMed1996

The efficacy of surgical modifications of the upper airway in adults with obstructive sleep apnea syndrome.

This paper, which has been reviewed and approved by the Board of Directors of the American Sleep Disorders Association, provides the background for the Standards of Practice Committee's parameters for the practice of sleep medicine in North America. The intent of this paper is to provide an overview of the surgical treatment of obstructive sleep apnea syndrome, to provide the basis for the American Sleep Disorders Association's practice parameters on this subject and to share our findings of metanalysis of previously published studies regarding uvulopalatopharyngoplasty. We searched MEDLINE from January 1966 through April 1993, with an update in February 1995, to provide a review of the application of surgical modifications of the upper airway to treat adults with obstructive sleep apnea syndrome. Operations to treat obstructive sleep apnea syndrome include nasal septal reconstruction; uvulopalatopharyngoplasty; uvulopalatopharyngoglossoplasty; laser midline glossectomy; lingualplasty; inferior sagittal mandibular osteotomy and genioglossal advancement, with hyoid myotomy and suspension (the entire process is referred to as GAHM); maxillomandibular osteotomy and advancement, and tracheotomy. Papers included in metanalysis provided preoperative and postoperative polysomnographic data on at least nine patients treated with uvulopalatopharyngoplasty for their obstructive sleep apnea. Analysis of the uvulopalatopharyngoplasty papers revealed that this procedure is, at best, effective in treating less than 50% of patients with obstructive sleep apnea syndrome. The site of pharyngeal narrowing or collapse, although identified by different and unvalidated methods, has a marked effect on the probability of success of uvulopalatopharyngoplasty. Patients who achieve a favorable response with uvulopalatopharyngoplasty tend to have less severe obstructive sleep apnea than those who do not. For patients who demonstrate retrolingual narrowing or collapse, other surgical modifications have been described, such as lingualplasty, GAHM, and maxillomandibular osteotomy and advancement. The studies to support the use of the surgical treatment of obstructive sleep apnea syndrome contain biases related to small sample size, limited follow-up and patient selection.

Adult↗

PubMed1996

Risk of radiation induced skin injuries from arrhythmia ablation procedures.

Catheter guided ablation of cardiac arrhythmias is an effective and safe procedure for the treatment of most supraventricular and selected ventricular tachycardias. Because catheter manipulation is fluoroscopically guided, there is risk of radiation induced injury, especially during prolonged procedures. The Food and Drug Administration has recently issued a bulletin warning of the risks of acute skin injury occurring during fluoroscopically guided procedures that result in an exposure level exceeding 2 Gray units (Gy). This study was performed as an investigation into the risk of radiation induced skin injury during arrhythmia ablation procedures. The amount of radiation exposure for 500 patients who underwent ablation was calculated based upon fluoroscopy times and the entrance dose of radiation (0.02 Gy/min). The mean radiation exposure was 0.93 +/- 0.62 Gy. Although 5.6% of patients (n = 28) received enough radiation exposure to reach the threshold dose (2 Gy) for early transient erythema, no clinical manifestations of acute radiation induced skin injury were observed. No patients achieved the threshold dose for irreversible skin injury. Patients undergoing AV node ablation or modification received significantly less radiation (0.39 +/- 0.40 Gy and 0.79 +/- 0.44 Gy, respectively) than patients undergoing other ablation procedures (0.94-1.45 Gy, P < 0.05). There was no association between the magnitude of radiation exposure and the presence of underlying heart disease. Patients undergoing ablation of accessory pathways were exposed to more radiation if there was a right-sided pathway (1.69 +/- 0.93 Gy) compared to other sites (0.87-1.24 Gy, P < 0.05). This study demonstrates that the risk of significant radiation induced skin injury during arrhythmia ablation procedures is low provided that precautions are taken to minimize radiation exposure.

Adolescent↗