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Biomedical subjects

David L Brown

Publications and source records attributed to David L Brown.

At least 55 records · Page 3Linked to original sources
PubMed2003

Analysis of the institutional volume-outcome relations for balloon angioplasty and stenting in the stent era in California.

BACKGROUND: Coronary artery stenting has become the predominant form of percutaneous coronary intervention. However, it is not clear whether a better outcome is conferred by stent placement in high-volume, more experienced centers as has been shown with balloon angioplasty. Furthermore, as stent procedures become more common, balloon angioplasty becomes less frequent. Thus, we separately analyzed the outcomes after coronary angioplasty and stenting in a large, unselected population to determine the effect of annual institutional angioplasty or stent volume on in-hospital outcomes after balloon angioplasty or stenting. METHODS: The California Office of Statewide Health Planning and Development database was queried to obtain discharge data on all patients in 1997 treated with percutaneous transluminal coronary angioplasty (PTCA) or a stent procedure. Hospitals were divided into low-volume (<200 procedures), intermediate-volume (200 to 400 procedures), and high-volume (>400 procedures) institutions as a function of their 1997 PTCA or stent volumes to assess the effect of volume on outcome. RESULTS: There were 44,276 percutaneous revascularization procedures performed in California in 1997, of which 57% involved coronary stent placement. Mortality rates after PTCA were 2.6%, 1.9%, and 1.4% in low-, intermediate- and high-volume PTCA hospitals, respectively (P <.001). The need for same-day coronary artery bypass grafting (CABG) after PTCA was 2.4%, 2.1%, and 1.2% in low-, intermediate- and high-volume PTCA hospitals, respectively (P <.001). Mortality rates after stent placement were 1.6%, 1.5%, and 1.1% in low-, intermediate-, and high-volume stent hospitals, respectively (P =.022). The need for same-day CABG after stent placement was 1.1%, 1.2%, and 0.8% in low-, intermediate-, and high-volume stent hospitals, respectively (P =.014). CONCLUSIONS: Short-term results of balloon angioplasty and stent procedures are improved when performed in high-volume hospitals.

Aged↗
PubMed2003

Risk factors for clinically relevant pulmonary embolism and deep venous thrombosis in patients undergoing primary hip or knee arthroplasty.

BACKGROUND: Prevention of thromboembolic complications after elective lower extremity arthroplasty has increasingly relied on routine thromboprophylaxis in all patients. Not all patients are at equal risk, however, and prophylaxis is not devoid of complications. The aim of this study was to examine the risk factors for clinically relevant pulmonary embolism and deep venous thrombosis after elective primary hip or knee arthroplasty in a large patient population. METHODS: During the 10-yr study period, 116 of 9,791 patients undergoing primary hip or knee arthroplasty at the authors' institution who experienced pulmonary embolism or deep venous thrombosis within 30 days of surgery were matched at a 1:1 ratio with patients undergoing the same surgery with the same surgeon who did not experience an adverse event. Medical records were reviewed, with data abstracted using a standardized data collection form. RESULTS: Increased body mass index (P = 0.031; odds ratio = 1.5 for each 5-kg/m2 increase) and American Society of Anesthesiologists physical status classification of 3 or greater (P = 0.005; odds ratio = 2.6) were found to independently increase the likelihood of pulmonary embolism or deep venous thrombosis. In addition, use of antithrombotic prophylaxis was found to decrease the likelihood of these thromboembolic events (P = 0.050; odds ratio = 0.2 for aspirin or subcutaneous heparin, and odds ratio = 0.4 for warfarin or low-molecular-weight heparin). CONCLUSIONS: In patients undergoing primary elective lower extremity arthroplasty, obesity, poor American Society of Anesthesiologists physical status classification, and lack of thromboprophylaxis are independent risk factors for clinically relevant thromboembolic events.

Aged↗
PubMed2003

Medical therapy in patients undergoing percutaneous coronary intervention: results from the ROSETTA registry.

BACKGROUND: Previous studies have examined medication use among patients with coronary artery disease who have suffered an acute myocardial infarction (MI). However, little is known about medication use among patients with coronary artery disease who undergo percutaneous coronary intervention (PCI). OBJECTIVE: To examine the patterns of use of medical therapy among patients who undergo PCI; and to examine the determinants of medical therapy in these patients. METHODS: The Routine versus Selective Exercise Treadmill Testing after Angioplasty (ROSETTA) registry is a prospective multicentre study examining the use of functional testing after PCI. The medication use was examined among 787 patients who were enrolled in the ROSETTA registry at 13 clinical centres in five countries. RESULTS: Most patients were men (mean age 61+/-11 years, 76% male) who underwent single vessel PCI (85%) with stent implantation (58%). At admission, discharge and six months, rates of acetylsalicylic acid use were 77%, 96% and 93%, respectively (discharge versus six months, P<0.0001). Rates of use of other oral antiplatelet agents were 11%, 59% and 2% (P=0.02). For individual anti-ischemic medications, rates of use were as follows: beta-blockers 49%, 58% and 59% (P<0.0001); calcium antagonists 34%, 43% and 42% (P<0.0001); and nitrates 42%, 56% and 43% (P<0.0001). Rates of use of combination anti-ischemic medications were as follows: triple therapy 7%, 9% and 9% (P<0.0001); double therapy 34%, 47% and 38% (P<0.0001); monotherapy 36%, 36% and 41% (P<0.0001); and no anti-ischemic therapy 23%, 8% and 12% (P<0.0001). Rates of use of angiotensin-converting enzyme inhibitors were 25%, 33% and 32% (P<0.0001), and rates of use of lipid lowering agents were 41%, 52% and 61% (P<0.0001). CONCLUSIONS: Trials and guidelines statements have favourably affected the rates of use of acetylsalicylic acid and other antiplatelet agents after PCI. However, in spite of patients undergoing a successful revascularization procedure, physicians do not reduce the use of anti-ischemic medical therapy.

Adrenergic beta-Antagonists↗
PubMed2002

Comparison of event and procedure rates following percutaneous transluminal coronary angioplasty in patients with and without previous coronary artery bypass graft surgery [the ROSETTA (Routine versus Selective Exercise Treadmill Testing after Angioplasty) Registry].

To compare 6-month post-percutaneous transluminal coronary angioplasty (PTCA) outcomes and cardiac procedure use among patients with and without prior coronary artery bypass graft (CABG) surgery, we examined 791 patients who were enrolled in the Routine versus Selective Exercise Treadmill Testing after Angioplasty (ROSETTA) Registry. The ROSETTA Registry is a prospective, multicenter registry that examines the use of functional testing after successful PTCA. Most patients were men (76%, mean age 61 +/- 11 years) who underwent single-vessel PTCA (85%) with stent implantation (58%). Baseline and procedural characteristics differed between patients with a prior CABG (n = 131) and patients with no prior CABG (n = 660), including Canadian Cardiovascular Society angina class III to IV (60% vs 49%, respectively, p = 0.03) and stenosis involving the proximal left anterior descending coronary artery (10% vs 22%, p = 0.004). Event rates among patients with prior CABG were higher than among patients with no prior CABG, including unstable angina (19% vs 11%, p = 0.02), myocardial infarction (2% vs 1%, p = 0.2), death (4% vs 2%, p = 0.08), and composite clinical events (22% vs 12%, p = 0.003). Furthermore, patients with prior CABG had higher rates of follow-up cardiac procedures, including angiography (24% vs 14%, p = 0.008) and PTCA (13% vs 7%, p = 0.04), but not repeat CABG (2% vs 3%, p = 0.8). A multivariate analysis that included baseline clinical and procedural characteristics demonstrated that prior CABG was a significant independent predictor of clinical events and cardiac procedure use (odds ratio 2.3, 95% confidence interval 1.5 to 3.5, p = 0.0001). Within the prior CABG group, patients with a PTCA of a bypass graft had a higher composite clinical event rate than patients with a PTCA of a native vessel (32% vs 17%, p = 0.05). In contrast, patients with a PTCA of a native vessel had event rates similar to those of patients with no prior CABG (17% vs 12%, p = 0.2). Thus, post-CABG patients have an increased risk of developing a cardiac event or needing a follow-up cardiac procedure during the 6 months after PTCA.

Angioplasty, Balloon, Coronary↗
PubMed2002

Immediate and delayed nerve repair: improved muscle mass and function with leukemia inhibitory factor.

In this study we examined the effect of leukemia inhibitory factor (LIF) on delayed repair of injured nerves. In a standard entubulation gap repair model of sciatic nerve in the rat, repair was performed immediately and after delays of 1 day, 1 week, and 4 weeks. Repaired nerves were treated with either LIF (10 ng) or saline, and assessment was by muscle mass and force contraction at 12 weeks after repair. After immediate nerve repair LIF administration resulted in 2.5- to 3-fold improvements compared with saline. In the 1-day delayed group, both saline and LIF treatment groups were comparable with that achieved with immediate repair combined with LIF. This result is consistent with the concept of preconditioning. In the 1-week delayed repair groups with LIF, muscle mass recovery and maximum force contraction were improved by 32% and 55%, respectively, compared with saline, whereas repairs delayed for 4 weeks showed increases of 50% and 36%. All delayed repairs treated with LIF were more effective than immediate repair with saline, but not as effective as primary repair with LIF. Our findings support the view that factors such as LIF may be efficacious for improving recovery of function in cases of delayed peripheral nerve repair.

Anastomosis, Surgical↗
PubMed2002

Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty.

BACKGROUND: There is limited information about the frequency of perioperative complications after elective primary orthopedic total hip and knee arthroplasty in contemporary practice. The purpose of this study was to determine the frequency of clinically relevant myocardial infarction, pulmonary embolism, deep venous thrombosis, and death within 30 days after elective primary hip or knee arthroplasty treated according to contemporary perioperative management. METHODS: The authors examined the medical records of consecutive patients undergoing hip or knee arthroplasty at their institution in a 10-yr period. Prospectively collected databases were used to identify patients with the diagnosis of myocardial infarction, pulmonary embolism, deep venous thrombosis, or death using strict validation criteria and diagnostic-certainty categories. RESULTS: A total of 10,244 patients underwent primary total hip or knee arthroplasty in the period of study. Of these, 224 patients had one or more adverse events (overall event rate: 2.2%; myocardial infarction: 0.4%; pulmonary embolism: 0.7%; deep venous thrombosis: 1.5%; death: 0.5%). Most adverse events (myocardial infarction, pulmonary embolism, and death) increased in frequency with older age, particularly for patients aged 70 yr or older. Myocardial infarction occurred more frequently in male patients. There were no differences in the overall event frequency between types of procedure. However, pulmonary embolism was highest in patients undergoing bilateral knee operations. CONCLUSIONS: The overall frequency of serious complications within 30 days after primary total hip or knee arthroplasty with contemporary practice was 2.2%. Accurate knowledge of the perioperative risks associated with widely performed elective operations can be used to implement management strategies that may further improve patient outcomes and decrease cost.

Adult↗
PubMed2002

Predicting cancer therapy-induced cardiotoxicity: the role of troponins and other markers.

Several anticancer drugs have been associated with cardiac toxicity, especially the anthracyclines and trastuzumab. The pathogenesis of anthracycline-associated toxicity has been well described, whereas the mechanism of trastuzumab-associated toxicity is unknown. Although routine cardiac imaging studies (e.g. echocardiogram or multiple gated acquisition scans) may identify subclinical evidence of myocardial dysfunction, available data do not support their routine use for monitoring asymptomatic patients undergoing cancer therapy. Other modalities such as nuclear medicine scintigraphy with indium-111-antimyosin antibody and endomyocardial biopsy have been shown to be useful in identifying early cardiac damage, but their routine use is limited by practical considerations such as feasibility and cost. Consequently, there is significant interest in developing simple and reproducible methods for identifying patients at risk for treatment-induced myocardial damage. Available data suggest that circulating markers such as troponins and natriuretic peptides could potentially be useful for this purpose. Measurement of plasma troponin levels are commonly used in clinical practice in order to provide diagnostic and prognostic information in patients with myocardial ischaemia. Elevated levels may likewise correlate with anthracycline-induced cardiac damage, although plasma levels are only minimally elevated (well below that associated with ischaemia), and elevations may persist for weeks or months after anthracycline exposure. Clinical trials are currently evaluating the role of these markers in predicting both early and late, clinical and subclinical damage associated with anthracyclines and trastuzumab.

Antibiotics, Antineoplastic↗
PubMed2002

Instrument scan strategies of F-117A pilots.

BACKGROUND: Eye tracking is an accurate and objective means of measuring an instrument scan pattern. The purpose of this study was to determine if prior aircraft experience, phase of flight, and autopilot mode modified the instrument scan pattern of F-117A pilots. METHODS: There were 23 F-117A pilots, grouped by prior aircraft experience, who flew an instrument approach manually and with autopilot while wearing an El Mar eye tracker in the F-117A simulator at Holloman AFB, NM. Number of fixations, dwell time, and percent total dwell time spent on nine individual instruments were collected and analyzed. RESULTS: The primary flight instrument was determined on the basis of pilot experience, and usage of the primary flight instrument varied significantly with phase of flight and manual vs. autopilot when ANOVA analysis was performed. CONCLUSIONS: Prior aircraft experience affects development of an instrument scan in a new aircraft. Prolonged dwell times on the primary flight instrument and changes in fixations/dwell time during autopilot mode have implications for instrument and cockpit design as well as cognitive load during novel situations. Further studies should be pursued.

Adult↗
PubMed2002

Comparison of in-hospital outcomes following early or delayed angioplasty for acute myocardial infarction.

BACKGROUND: Studies of primary angioplasty for treatment of acute myocardial infarction (AMI) have not appeared to demonstrate a reduction in efficacy as a function of time to treatment. We sought to compare the outcomes of patients treated in New York State with primary angioplasty within 6 hours of symptom onset to those treated between 6 and 23 hours after the onset of AMI. METHODS: We used data from the 1995 Coronary Angioplasty Reporting System of the New York State Department of Health to compare the in-hospital outcomes of patients treated with early (within 6 hours) or delayed angioplasty (6 23 hours) for AMI. RESULTS: Early angioplasty (within 6 hours after onset of chest pain) was attempted in 957 patients (71.3%), while 385 patients (28.7%) had a delayed procedure (6 23 hours after the onset of chest pain). Patients who underwent delayed angioplasty were older (mean age, 62.6 years versus 60.4 years in the early group; p < 0.01) and more often female (36% vs. 28% in the early treatment group; p < 0.001). Patients treated early more frequently demonstrated hemodynamic instability (13.6% versus 9.1% in the late treatment group; p = 0.02), malignant ventricular arrhythmia (8.5% versus 2.9% in the late treatment group; p < 0.001) and cardiogenic shock (6.6% versus 1.8% in the late treatment group; p < 0.001). Overall in-hospital mortality was 63/1,342 (4.7%) with no difference based on early or delayed angioplasty (5.2% versus 3.4%, respectively; p = NS). The composite of the major adverse cardiac events including in-hospital death, reinfarction and emergency bypass surgery did not differ significantly between the early and delayed groups (7.7% versus 5.5%, respectively; p = NS). In multivariable models, delayed angioplasty was not an independent predictor of either in-hospital mortality or major adverse cardiac events. CONCLUSION: Delayed reperfusion does not influence in-hospital clinical outcomes following PTCA for acute myocardial infarction.

Age Factors↗
PubMed1994

Altered reactivity of isolated segmental lumbar arteries of dogs following exposure to ethanol and phenol.

Celiac plexus neurolysis is a useful analgesic technique in patients with upper abdominal cancer. Although complications are infrequent, occasionally celiac neurolysis results in paraplegia. It is hypothesized that paraplegia after celiac neurolysis results from neurolytic drug-induced spasm of lumbar segmental arteries that perfuse the spinal cord, although no data are available to support or refute the idea. Whether drugs used for celiac plexus neurolysis alter the reactivity of dogs' lumbar segmental arteries was studied in vitro. Rings of lumbar segmental arteries, suspended in Krebs-Ringer solution in organ baths, were passively stretched to the optimal point on their length-tension curve. After a 45-min rest the responsiveness of each ring was established by adding an ED50 concentration of norepinephrine to the bath. Subsequently, Krebs-Ringer solution containing a single concentration of phenol or ethanol was added. Concentrations studied included 1%, 3%, 6%, 7%, 8%, 9%, and 12% phenol; and 3%, 6%, 10%, 25%, 50%, 75%, and 90% ethanol. The magnitude of the phenol-induced contractile response was directly related to concentration, with 8%, 9% and 12% phenol, producing sustained contractile responses compared to norepinephrine-induced control contractile responses. The ethanol-induced contractile response was inversely related to concentration. Ethanol (3% and 6%) produced sustained contractile responses compared to norepinephrine-induced control contractile responses. Studies were then done to further elucidate the agonist properties of phenol and ethanol. The contractions caused by ethanol or phenol did not appear to be mediated through adrenergic, opioid, muscarinic, or serotonin receptors or sodium channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Cardiovascular effects of ephedra alkaloids: a comprehensive review.

The Ephedra alkaloids have received much press lately secondary to reported adverse events in those using whole extracts as "dietary supplements" for weight loss or athletic performance enhancement. These reports are troubling given the increasing use of these supplements by the general public. We reviewed the available literature as well as online material on these compounds, including information on their pharmacology, regulation, effects on weight loss and athletic performance, and adverse events. Extracts of Ephedra shrubs contain highly active alpha- and beta-adrenergic agonists that have profound effects on the heart and vasculature. Evidence for their effectiveness is limited. Adverse cardiovascular and cerebrovascular effects, including stroke, myocardial infarction, and sudden death, temporally related to their use are well described. The recent Food and Drug Administration ban on these compounds is not broad enough. Ephedra supplements contain a highly bioactive class of compounds that pose a significant risk to the public under the current regulatory framework. More stringent oversight by regulatory authorities is required to minimize the incidence of adverse events.

Alkaloids↗