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Biomedical subjects

L Harris

Publications and source records attributed to L Harris.

At least 109 records · Page 6Linked to original sources
PubMed1992

Pathophysiology and prognostic significance of Holter-detected ST segment depression after myocardial infarction. The Tissue Plasminogen Activator: Toronto (TPAT) Study Group.

OBJECTIVES: We performed Holter monitoring on days 4 and 7 after acute myocardial infarction in 109 patients to assess whether ST segment shift would identify those with more severe coronary artery disease, left ventricular dysfunction and unfavorable prognosis. BACKGROUND: Silent myocardial ischemia is a frequent and prognostically significant event after acute myocardial infarction. However, the specific pathophysiologic mechanisms and the impact of thrombolytic therapy are uncertain. METHODS: In addition to Holter monitoring, patients underwent exercise testing, radionuclide angiography on days 1 and 9 and quantitative coronary angiography on day 9. RESULTS: Thirty-five patients (32%) had ST segment depression and had similar recombinant tissue-type plasminogen activator (rt-PA) treatment assignment and a reduced cross-sectional area of the infarct-related artery (0.59 +/- 0.57 vs. 1.04 +/- 1.26 mm2, p < 0.05). Global left ventricular function improved from day 1 to day 9 in patients without (4% +/- 11%, p < 0.001) but not in those with (0% +/- 7%) ST segment depression. In-hospital event rates were similar; however, follow-up 18 +/- 11 months after hospital discharge revealed a greater frequency of death and recurrent myocardial infarction in patients with compared with those without ST segment depression (27% vs. 6%, p = 0.03). CONCLUSIONS: After acute myocardial infarction, approximately one third of patients have ST segment depression on Holter monitoring, independent of the use of thrombolytic therapy. The unfavorable prognosis observed in these patients may be related to greater lumen obstruction in the infarct-related artery and lack of improvement in left ventricular function.

Cardiac Catheterization↗
PubMed1992

Mechanisms of spontaneous shift of surface electrocardiographic configuration during ventricular tachycardia.

OBJECTIVES: The aim of this study was to examine, with multichannel direct cardiac mapping techniques, the mechanisms of spontaneous shift of the QRS configuration in the surface electrocardiogram during episodes of ventricular tachycardia. BACKGROUND: Ventricular tachycardias demonstrating a spontaneous shift in their surface electrocardiographic (ECG) features are occasionally encountered. It is not known whether such changes in configuration are primarily due to a significant change in the tachycardia site of origin or represent alterations in patterns of endocardial and epicardial activation. Knowledge of these features would be helpful, particularly when ablative therapy is considered for the arrhythmias. METHODS: During map-directed cardiac surgery, episodes of ventricular tachycardia were mapped from 224 epicardial and endocardial sites. Episodes of pleomorphic tachycardia were identified and isochronal maps of endocardial and epicardial activation were constructed from representative beats before and after the change in configuration. RESULTS: From 52 consecutive patients who underwent detailed intraoperative mapping, 9 patients with pleomorphic ventricular tachycardia were identified in whom 14 episodes of spontaneous shift occurred. An analysis of the epicardial activation patterns revealed that the sites of earliest epicardial breakthrough showed significant alteration at the time of QRS shift in all occurrences. In 10 of these shift episodes, however, the sites of tachycardia origin, located on the endocardial surface, remained closely adjacent (< 2 cm apart). Although these sites of origin remained relatively constant, significant alterations in the patterns of endocardial activation were seen in most episodes. These included changes in the direction of propagation of the wave front of activation and shifts between monoregional and figure eight patterns of activation. CONCLUSIONS: In most episodes of pleomorphic ventricular tachycardia, the arrhythmia site of origin remains relatively constant. However, patterns of epicardial activation do undergo significant change and appear to be the major determinant of the QRS configuration on the surface ECG.

Cardiac Pacing, Artificial↗
PubMed1992

Use of telemetry functions in the assessment of implanted antitachycardia device efficacy.

Twenty patients (aged 50 +/- 21 years and mean left ventricular ejection fraction 37 +/- 17%) with recurrent ventricular arrhythmias were treated with an investigational, implantable combined antitachycardia-pacing cardioverter defibrillator. The device's telemetry capabilities include both stored (1-second snapshots) and real-time display of endocardial and device-circuit signals. The device can store these before, during and after up to 50 tachycardia and antitachycardia pacing episodes. All stored events are indexed to a 24-hour internal clock. During 10.1 +/- 5.1 months of follow-up, the device was used in 11 of 20 patients. In the entire group, antitachycardia pacing was activated on 44 +/- 14 occasions per patient (total 874) and shock delivery occurred on 8 +/- 14 occasions per patient (total 156). Reconstruction by stored telemetry of all device-therapy episodes was possible. Twenty-six percent of all shocks delivered were not appropriate and were due to atrial arrhythmias in 2 patients and dysfunction of the sensing lead in 3. The absence of a relation between symptoms and appropriate shock delivery was documented in 1 patient. Antitachycardia pace acceleration occurred in 5.3% of cases; 7% of attempts at pacing were unsuccessful and needed shock therapy. It is concluded that the enhanced telemetry available in newer antitachycardia devices enables more accurate assessment of device use and enhances diagnosis of inappropriate therapy delivery.

Electric Countershock↗
PubMed1992

American Indian--Alaska Native youth health.

OBJECTIVE: To assess risk behaviors, health problems, worries and concerns, and resiliency-promoting factors among American Indian-Alaska Native adolescents. DESIGN: Survey. SETTING: Nonurban schools from eight Indian Health Service areas. PARTICIPANTS: A total of 13,454 seventh- through 12th-grade American Indian-Alaska Native youths. MAIN OUTCOME MEASURES: revised version of the Adolescent Health Survey, a comprehensive, anonymous, self-report questionnaire with 162 items addressing 10 dimensions of health. RESULTS: Poor physical health was reported by 2% of the study sample and was significantly correlated with social risk factors of physical and/or sexual abuse, suicide attempts, substance abuse, poor school performance, and nutritional inadequacies. Injury risk behaviors included never wearing seatbelts (44%), drinking and driving (37.9% of driving 10th through 12th graders), and riding with a driver who had been drinking (21.8%). Physical and sexual abuse prevalence was 10% and 13%, respectively, with 23.9% of females reporting physical abuse and 21.6% of females reporting sexual abuse by the 12th grade. Almost 6% of the entire sample endorsed signs of severe emotional distress. Eleven percent of the teens surveyed knew someone who had killed himself or herself, and 17% had attempted suicide themselves. Sixty-five percent of males and 56.8% of females reported having had intercourse by the 12th grade. Weekly or more frequent alcohol use rose from 8.2% of seventh graders to 14.1% by the 12th grade; for males, the survey noted an increase in regular alcohol use of 3% to 5% a year to 27.3% by the 12th grade. For each variable measured, rates are much higher for American Indian adolescents than those for rural white Minnesota youth, except for age at first intercourse and alcohol use. CONCLUSIONS: American Indian-Alaska Native adolescents reported high rates of health-compromising behaviors and risk factors related to unintentional injury, substance use, poor self-assessed health status, emotional distress, and suicide. Interventions must be culturally sensitive, acknowledge the heterogeneity of Indian populations, be grounded in cultural traditions that promote health, and be developed with full participation of the involved communities.

Adolescent↗
PubMed1992

Firearms suicides in Australia.

OBJECTIVE: To examine the rates of suicide by firearms in the five larger Australian States during 1968-1989, and to relate them to differences between those States. We hypothesised that (i) restrictive gun legislation will have reduced the firearms suicide rate in South Australia after 1980, and (ii) firearms suicides would be shown to be more common in States with larger rural:urban population ratios. DESIGN: Data supplied by the Australian Bureau of Statistics were analysed by sex, State and year of suicide. Differences between the firearms suicide rates of capital city and rural dwellers, and of different age-groups, were recorded. RESULTS: Firearms suicide rates in South Australia declined significantly after 1980, following proclamation of gun legislation, in contrast to the four other larger States where an increase in firearms suicides was recorded. The firearms suicide rate in Queensland has remained consistently higher than in the other four larger States during 1968-1989. The number of Australian firearms suicides per year fell by 25% from a peak of 572 in 1987 to 451 in 1989. CONCLUSIONS: Further reductions in the Australian firearms suicide rate might be achieved by tightening gun laws and by a media campaign aimed at reducing easy access by males to guns in rural households.

Adolescent↗
PubMed1992

Ventricular tachycardia after surgical repair of tetralogy of Fallot: results of intraoperative mapping studies.

OBJECTIVES: Four patients with previous repair of tetralogy of Fallot and ventricular tachycardia underwent map-guided surgery to ablate the arrhythmias. BACKGROUND: Although patients with repaired tetralogy of Fallot are at increased risk of sudden death due to ventricular tachycardia, little is known of the origin and mechanism of this arrhythmia. METHODS: A customized right ventricular balloon with 112 electrodes was used to record endocardial activation and, where possible, simultaneous epicardial recordings were obtained with a sock electrode array. Three patients had an aneurysm of the right ventricular outflow tract and one had a septal aneurysm. All had moderate to severe pulmonary valve insufficiency. Preoperative electrophysiologic study demonstrated inducible rapid (cycle length 180 to 300 ms) hemodynamically unstable monoform ventricular tachycardias. RESULTS: Intraoperatively, five different tachycardias (two in one patient) were induced and mapped. The sites of earliest activation were located in the subendocardium of the right ventricular outflow tract in all, but they varied widely among the septum, free wall and parietal band and could not be identified by visible scar. All were due to a macroreentrant circuit initiated by a critical delay in activation beyond a functional arc of block. Two patients treated by cryoablation while the heart was beating and perfused at normal temperature had inducible ventricular tachycardia postoperatively. In the two subsequent patients, the application of cryoablation under anoxic cardiac arrest resulted in noninducibility of arrhythmia. CONCLUSIONS: Ventricular tachycardia in tetralogy of Fallot in these four patients was caused by macroreentry in the right ventricular outflow tract. Surgical success depends on detailed mapping and cryoablation under anoxic cardiac arrest. In patients at risk of sudden death, map-directed surgery may offer distinct advantages over either implantable devices or drug therapy.

Child↗
PubMed1992

Endocardial mapping of ventricular tachycardia in the intact human heart. II. Evidence for multiuse reentry in a functional sheet of surviving myocardium.

OBJECTIVE: The purpose of this study was to obtain improved detection and characterization of reentrant circuits in the infarcted human ventricle. BACKGROUND: The return path of reentrant ventricular arrhythmias usually is not manifested in clinical mapping studies but is thought to be formed by isolated bundles of surviving myocytes whose presence is difficult to detect by standard recording techniques. METHODS: We obtained simultaneous unipolar and high gain bipolar recordings using a left ventricular endocardial balloon array in 10 patients with chronic ischemic heart disease undergoing intraoperative mapping of ventricular tachycardia. RESULTS: Three patients demonstrated seven separate ventricular tachycardias that utilized a return tract that was manifested on up to 20% of all left ventricular electrode sites. The recordings suggested an extensive sheet of surviving myocardial fibers with multiple entry and exit points allowing for different reentrant paths at different times all in the same heart. In one patient, five different ventricular tachycardias could be induced, four of which utilized such a sheet. Two of these tachycardias had the same exit point (site of origin) but two different entry points with a long and short return path resulting in long and short tachycardia cycle lengths. The same sheet sustained another tachycardia with one entry and two exit points resulting in two separate "sites of origin" on the endocardium. Such sheets also were seen to insert into the left bundle system. In one patient portions of the sheet could be detected epicardially. CONCLUSION: The existence of such a structure of surviving myocardium with functional pleomorphism may account for unexplained changes in tachycardia cycle length, epicardial entrainment and spontaneous morphologic changes during ventricular tachycardia.

Cardiac Pacing, Artificial↗
PubMed1992

Is breast feeding possible after reduction mammaplasty?

The purpose of this study was (1) to evaluate the frequency of breast feeding in patients who had given birth following reduction mammaplasty using an inferiorly based pedicle flap and (2) to identify operative and nonoperative factors that may affect breast feeding following reduction mammaplasty. Seventy-three patients between the ages of 18 and 40 years were contacted and sent a standardized questionnaire. Data collected included age at pregnancy, duration of breast feeding, difficulties while breast feeding, and reasons for discontinuing breast feeding. A total of 20 patients of the 68 who responded had become pregnant following reduction mammaplasty. All 20 women lactated. Seven of these women (35 percent) went on to a breast-feed successfully, whereas 13 (65 percent) decided not to breast-feed or discontinued breast feeding for a variety of personal reasons.

Adolescent↗
PubMed1992

Isolation of swine infertility and respiratory syndrome virus (isolate ATCC VR-2332) in North America and experimental reproduction of the disease in gnotobiotic pigs.

A recent epizootic of swine infertility and respiratory syndrome (SIRS) in a Minnesota swine herd was investigated. Examination of a sow, neonatal piglets, and stillborn fetuses obtained during the epizootic from the affected herd revealed interstitial pneumonitis, lymphomononuclear encephalitis, and lymphomononuclear myocarditis in the piglets and focal vasculitis in the brain of the sow. Fetuses did not have microscopic lesions. No cause for the infertility and respiratory syndrome was determined. Therefore, attempts were made to experimentally reproduce the disease. Eleven 3-day-old gnotobiotic piglets exposed intranasally to tissue homogenates of piglets from the epizootic became inappetent and febrile by 2-4 days postexposure and had interstitial pneumonitis and encephalitis similar to that seen in the field outbreak. After 2 blind passages in gnotobiotic piglets, tissue homogenates were cultured on continuous cell line CL2621, and a cytopathic virus (ATCC VR-2332), provisionally named SIRS virus, was isolated. Gnotobiotic piglets exposed intranasally to the SIRS virus developed clinical signs and microscopic lesions that were the same as those in piglets exposed to the tissue homogenates, and the virus was reisolated from their lungs. This is the first isolate of SIRS virus in the United States that fulfills Koch's postulates in producing the respiratory form of the disease in gnotobiotic piglets and the first report of isolation and propagation of the virus on a continuous cell line (CL2621). The virus is designated as American Type Culture Collection VR-2332.

Animals↗
PubMed1992

Characterization of swine infertility and respiratory syndrome (SIRS) virus (isolate ATCC VR-2332).

The characterization of an isolate of swine infertility and respiratory syndrome (SIRS) virus (ATCC VR-2332) is reported. A commercial cell line (CL2621) was used for the propagation of the virus for all assays. Laboratory studies indicate that this isolate is a fastidious, nonhemagglutinating, enveloped RNA virus. Cesium chloride-purified virions visualized by electron microscopy were spherical particles with an average diameter of 62 nm (range: 48-83 nm) and a 25-30 nm core surrounded by an envelope. Virus replication was restricted to the cytoplasm, as demonstrated by immunofluorescence. The virus did not react serologically with antisera to several common porcine viruses or with antisera to known viruses in the alphavirus, rubivirus, pestivirus, and ungrouped lactic dehydrogenase virus genera of the Togaviridae. However, convalescent sow sera and rabbit hyperimmune sera neutralized the SIRS virus at titers of 1:256 and 1:512, respectively. The virus was stable at 4 and -70 C, but was labile at 37 and 56 C. The properties of this isolate of SIRS virus resemble those of the family Togaviridae but do not match the described genera.

Animals↗
PubMed1992

Antigenic comparison of Lelystad virus and swine infertility and respiratory syndrome (SIRS) virus.

This study reports the antigenic relatedness of isolates of Lelystad virus collected in the Netherlands, Germany, and the United States. The binding of antibodies directed against these isolates was tested in a set of field sera collected during outbreaks of porcine epidemic abortion and respiratory syndrome in Europe and outbreaks of swine infertility and respiratory syndrome (SIRS) in North America. Two sets of sera from pigs experimentally infected with Lelystad virus or SIRS virus were also tested. Although all 7 isolates reacted with anti-Lelystad virus sera, antigenic variation was considerable. The 4 European isolates resembled each other closely, but differed from the American isolates, and the 3 American isolates differed antigenically from each other. To reliably diagnose Lelystad virus infection, a common antigen must first be identified.

Animals↗
PubMed1992

Clostridial septicemia in an urban hospital.

The records of 56 patients at an urban hospital who had positive blood cultures for clostridia were reviewed. Each patient was classified as immunologically normal or immunosuppressed. Data were collected on clinical history, type of clostridial bacteremia, physical and laboratory determinants of infection, therapeutic intervention, clinical course and outcome. Of the 56 patients, 22 were determined to be immunosuppressed. Among all 56 patients, 28 had a malignancy, usually gastrointestinal or hematologic in origin. Fever, leukocytosis and abdominal pain were common in both groups. Clostridial bacteremia almost always heralded clostridial septicemia. A gastrointestinal source of infection, particularly carcinoma of the colon or rectum or enterocolitis, was evident or presumed in 43 of the 56 patients. Clostridium perfringens was the most frequently isolated microorganism, but C. septicum was associated with more complications and a higher mortality rate. Septic complications and mortality were higher among the patients with immunosuppression.

Adolescent↗
PubMed1992

Demography of sexual orientation in adolescents.

This study was undertaken to explore patterns of sexual orientation in a representative sample of Minnesota junior and senior high school students. The sample included 34,706 students (grades 7 through 12) from diverse ethnic, geographic, and socioeconomic strata. Five items pertaining to sexual attraction, fantasy, behavior, and affiliation were embedded in a self-administered survey of adolescent health. Overall, 10.7% of students were "unsure" of their sexual orientation; 88.2% described themselves as predominantly heterosexual; and 1.1% described themselves as bisexual or predominantly homosexual. The reported prevalence of homosexual attractions (4.5%) exceeded homosexual fantasies (2.6%), sexual behavior (1%), or affiliation (0.4%). Gender differences were minor; but responses to individual sexual orientation items varied with age, religiosity, ethnicity, and socioeconomic status. Uncertainty about sexual orientation diminished in successively older age groups, with corresponding increases in heterosexual and homosexual affiliation. The findings suggest an unfolding of sexual identity during adolescence, influenced by sexual experience and demographic factors.

Adolescent↗
PubMed1992

Experimental reproduction of swine infertility and respiratory syndrome in pregnant sows.

The purpose of this study was to experimentally reproduce swine infertility and respiratory syndrome (SIRS). Six multiparous sows were intranasally inoculated at 93 days of gestation with lung homogenates from clinically affected pigs, and 3 additional sows were similarly inoculated with a virus isolated in cell culture from the lung homogenate (SIRS virus, isolate ATCC VR-2332). Inoculated sows developed transient anorexia, farrowed up to 7 days prematurely, and delivered a mean of 5.8 live pigs and 6.0 dead fetuses/litter. Clinical signs of disease were not observed in 3 sham-inoculated control sows that delivered a mean of 12.7 live pigs and 0.3 stillborn fetuses/litter. The SIRS virus was isolated from 50 of 76 live-born and stillborn fetuses from the 9 infected litters. Virus was not isolated from 26 autolyzed fetuses or 15 control pigs. Six of 9 inoculated sows developed neutralizing antibodies to SIRS virus. The reproductive effects found in these experiments were identical to those found in field cases. On the basis of our findings, virus isolate ATCC VR-2332 causes the reproductive failure associated with SIRS.

Animals↗
PubMed1991

Pulse oximetry monitoring outside the intensive care unit: progress or problem?

OBJECTIVE: To evaluate the use of continuous pulse oximetry monitoring in general care units. DESIGN: Hemoglobin oxygen saturation data collected prospectively by use of pulse oximetry with concurrent review of the medical record. SETTING: General medical-surgical nursing units in a large, tertiary care university hospital. PATIENTS: Forty patients on two nursing units monitored with continuous, bedside pulse oximetry at the request of their primary physicians. MEASUREMENTS: All patients had continuous pulse oximetry monitoring. A research associate visited the bedside two or three times daily and recorded saturation compared with time data from the previous 8.75 hours. Patients were studied for 36 hours or until pulse oximetry monitoring was discontinued. Episodes of desaturation were counted. Patient charts were reviewed for documentation of desaturation in either nursing or physician notes. Orders adjusting oxygen therapy or other respiratory therapy within 12 hours of any desaturation episode were also recorded. MAIN RESULTS: Thirty of the 40 patients (75%) had at least one episode of desaturation to less than 90%; 23 (58%) had at least one episode to less than 85%. Desaturation episodes were documented in nursing notes for only 33% of those patients who desaturated to less than 90% and in physician notes in only 7% of cases. Changes in respiratory therapy were ordered in 20% of patients who desaturated to less than 90% and in only 26% who desaturated to less than 85%. CONCLUSIONS: Despite their repeated occurrence, episodes of hypoxemia were rarely documented in either nursing or physician notes. Further, even in patients who had episodic desaturation, pulse oximetry monitoring had little effect on changes in physician-directed respiratory care.

Adult↗
PubMed1991

A team format for the Global Assessment Scale: reliability and validity on an inpatient unit.

The Global Assessment Scale (GAS) is a 100-point rating instrument which purports to measure psychological adjustment on a continuum from self-actualization to severe regression. Its reliability and validity were examined on the admitting ward of a state hospital where GAS ratings are assigned to patients by computing a mean of the individual ratings assigned by a team of clinicians. Results showed such team GAS ratings to have good reliability. As for validity, team GAS predicted the outcomes of court hearings at two stages of the civil commitment process and showed construct validity in its relevant correlations with the Psychotic Inpatient Profile. A predicted association between team GAS and a ward atmosphere measure was not obtained. Taken as a whole, the results support the use of team GAS ratings in inpatient settings.

Adaptation, Psychological↗