bluuebunny/crossref_metadata_2025 huggingface dataset:
Depression, Physical Health Impairment and Service Use Among Older Adults
Authors: Badger Terry A.
Published: May 2007

Abstract The purposes of this study were: (1) to compare service use and need among 80 community‐dwelling older adults (55 women and 25 men): and (2) to examine the influence of depression on service use and need. Participants were divided into three groups based on their depression scores (no depression, mild depression, severe depression) and compared on a wide range of services (e.g., medical services, social/recreational, transportation) typically used by older adults. There were no significant differences among the three groups for demographic characteristics and chronic illness types, but there were significant differences for physical health impairment (PHI). When controlling for PHI, significant differences were found among the groups for mental health services, psychotropic medications, number of sick days, hospitalizations, home help, frequency of transportation, social/recreational services, and sports‐related activities. Mildly and severely depressed older adults used and needed more medical services than did their non‐depressed cohorts, but used less of other types of services (e.g., social/recreational services). Depression was a significant predictor of social/recreational service use. and for need of mental health services, psychotropic medications, financial assistance, and assessment and referral services. A consistent pattern was found of depression influencing service use and need.
A Qualitative Assessment of Inner City Elementary School Children's Perceptions of Their Neighborhood
Authors: Polivka Barbara J. , Lovell Mariann , Smith Barbara A.
Published: May 2007

Abstract Three hundred seventy‐nine youths from an inner city elementary school were surveyed to determine their perceptions of their neighborhood. Using a qualitative, word association format, older students responded to 20 descriptive words (e.g., dirty, safe, quiet, dangerous) while younger youths drew pictures in response to three words (safe, sad, happy). Using content analysis techniques, findings indicated that the youths found neighborhood areas and residents that were perceived as safe, quiet, beautiful, friendly, fun/happy, and helpful. However, safety issues and a dirty, noisy neighborhood also emerged as major themes. Collaborative initiatives focusing on cleaning up the neighborhood and reducing violence are suggested, as are areas of intervention and further research.
Prostate Cancer Education in African American Churches
Authors: Weinrich Sally , Holdford Diane , Boyd Marlyn , Creanga Dana , Cover Kay , Johnson Alonzo , Frank‐Stromborg Marilyn , Weinrich Martin
Published: May 2007

Abstract The use of churches as recruitment sites of African Americans into health promotion activities is a popular theme in the 1990s literature. This research measured the impact of previous exposure to cancer on participation in an educational program and a free prostate cancer screening. Cues to action from the Health Belief Model provided the conceptual framework. Over 500 men attended a prostate cancer educational program at their church. Men who participated in the educational program and completed the questionnaire were given a voucher that they could take to their doctor of choice for a free prostate cancer examination. Having a member of the congregation who was previously diagnosed with cancer was a significant cue to attendance at the educational program (P= 0.03). Recommendations for future cancer screening in churches are given.
Population‐Based Public Health Nursing Interventions: A Model from Practice
Authors: Keller Linda Olson , Strohschein Susan , Lia‐Hoagberg Betty , Schaffer Marjorie
Published: May 2007

AbstractIn a changing and complex health care system, public health nurses face challenges to explain their work and contributions to health outcomes. In response to this need, the Minnesota Department of Health, Section of Public Health Nursing, initiated a process to describe public health nursing interventions. The Public Health Nursing Interventions (PHI) Model was developed through a collaborative process by public health nurses at the state and local levels. The purpose of the model was to define more clearly the practice of public health nursing and to describe better the work of public health nurses at the community and systems levels. The PHI model identifies 17 interventions and provides practice examples at the systems, community and individual/family levels. The model defines a broader view of the mission and scope of public health nursing. Practice examples are given for agency staff, administrators, educators, and policy makers.
Long‐Term Maternal‐Child Home Visiting
Authors: Byrd Mary E.
Published: May 2007

Abstract Families with children with special needs, with acutely and chronically ill children, and with foster children comprise an increasing portion of many public health nurses' paseloads. The nursing processes during maternal‐child home visiting have not been identified and variations in these processes, as well as their attendant outcomes, across client populations have not been described. The aim of this study was to describe the process of home visiting, as it was enacted by an experienced nurse, and to identify potential influencing factors and attendant consequences. During this field research investigation, one nurse in a visiting nurse association in rural New England was observed and interviewed throughout her day, every one to two weeks over a period of eight months. A total of 53 home visits were observed, three clients were interviewed subsequent to visits, and documents and records were reviewed. A specific type of home visiting, labeled child‐focused, which the nurse conducted in three distinct patterns—single, short‐, and long‐term, emerged. The long‐term pattern is described in this article. An admiring, familiar, trusting, supporting, reassuring, and validating seeing and exchanging subprocess ran through these visits. Potential maternal, child, and environmental consequences were identified.
Facilitators, Barriers, and Strategies for Exercise in European American Women in the Community
Authors: Nies Mary A. , Vollman Michael , Cook Thomas
Published: May 2007

Abstract A qualitative study was undertaken to explore the facilitators, barriers, and strategies that contribute to exercise performance in European American (EA) women. Focus groups were used to obtain information about the experiences of EA women concerning physical activity in their daily lives. Sixteen women aged 35‐50 were recruited to participate in one of two focus groups. Focus group transcripts were coded and content analyzed. Major facilitators identified were social support, accommodating schedule, self improvement, supportive environment, and individual factors. Major barriers were lack of family support, unaccommodating schedule, consequences of exercise, environmental barriers, and individual barriers. The findings of this study can be used to develop nursing interventions designed to decrease sedentary behavior in EA women.
A Rural Vision of a Healthy Community
Authors: Hornberger Cynthia A. , Cobb Ann Kuckelman
Published: May 2007

ABSTRACTNurses can take a leadership role in the process of helping rural Americans to recognize and implement their vision of a healthy community. This necessitates an understanding of rural communities' perceptions of health and health care and allows nurses to more appropriately provide primary health care. As defined by the World Health Organization, primary health care is comprised of concepts of essentiality, community participation, intersectoral collaboration, access, and empowerment (Barnes et al., 1995). A focused ethnography involving 150 residents was conducted in a midwestern rural community and included 56 personal and 8 focus group interviews. A qualitative analysis of responses to the question. “What is your vision of a healthy community?” was conducted using Leininger's (1985) categories of economics, social‐kinship, cultural, political‐legal, religion, technology, and education. An eighth category of environmental concern emerged from the data. Responses were further assimilated into descriptive statements reflecting the community's vision of a healthy community, including issues of accessible and technologically adequate healthcare, job availability, strong community support by schools and churches, a caring community membership, and an attractive, pollution‐free environment. This analysis demonstrates the need for application of primary health care at the level of community in designing services to achieve healthy rural communities.
Older Women's Beliefs About Physical Activity
Authors: Conn Vicki S.
Published: May 2007

ABSTRACT Physical activity may contribute to important health and well‐being outcomes among older adults. Efforts to understand determinants of physical activity are necessary to plan effective interventions. The theory of planned behavior has been successfully applied to a variety of health behaviors. Previous research using the theory of planned behavior has not addressed beliefs about overall physical activity among communitydwelling older women. Qualitative interviews were conducted with 30 older women to identify behavioral beliefs, perceived control beliefs, and normative beliefs, which influence physical activity decisions. Content analyses of responses revealed three major themes: social influences on physical activity, psychosocial benefits of activity, and joint problems and fatigue as factors that interfere with activity. These findings about physical activity were compared with published findings about episodic exercise among 30 similar women who took part in an episodic exercise study. The result was the discovery that the women in this study talked about physical activity as embedded in their social lives while the women in the episodic exercise study viewed exercise as separate from their daily lives. These findings of beliefs about overall physical activity suggest a social model may be useful in planning public health interventions to increase activity among older women.
Acceptance of Nurse Practitioners and Physician Assistants in Meeting the Perceived Needs of Rural Communities
Authors: Baldwin Kathleen A. , Sisk Rebecca J. , Watts Parris , McCubbin Jan , Brockschmidt Beth , Marion Lucy N.
Published: May 2007

ABSTRACTNurse practitioners and physician assistants have provided a partial solution to the shortage of primary care services in medically underserved rural areas. This paper describes the results of a study exploring community acceptance of nurse practitioners and physician assistants in rural medically underserved areas. Community acceptance in the context of this study implies not only satisfaction with care received, but also willingness of the community to support NP/PA practice through its infrastructure and encourage members to initially seek and continue to receive care from an NP or PA. Five focus groups were conducted in each of five rural medically underserved communities. The two most pervasive findings were the lack of previous exposure to NPs and PAs and the general belief that NPs and PAs would be accepted in these communities if certain conditions could be met. The theme of conditional acceptance included both personal and system factors. Personal factors included friendliness, competence, willingness to enter into the life of the community, and the ability to keep information confidential. System factors considered critical for acceptance included service type, integration with the existing health care system, cost, geographic proximity, and availability. The results of this study offer insight into community attitudes and suggest marketing strategies for those who plan to introduce NP or PA services into rural communities.
Development of a Community‐Based Diabetes and Hypertension Preventive Program
Authors: Wang Chen‐Yen , Abbott Lisa J.
Published: May 2007

ABSTRACT The purpose of this project was to develop rapport with a Chinese Community Association and then establish preventive diabetic and hypertension programs with the Chinese in Chinatown, Hawaii. Subjects were recruited from this Chinese Community Association. Two hundred Chinese responded to the invitation. Among these. 75 individuals had either Type 2 diabetes, hypertension or both. Thirty‐six males and 39 females ranging in age from 51 years old to 96 years old (Mean = 71.76, SD = 9.58) participated. Surveys and educational programs were carried out in Chinese. Results were described in terms of quantitative measures (family support and health outcomes) and qualitative experiences (case studies). Eighty percent of participants had decreased their diastolic blood pressure from above 95 mmHg to below 90 mmHg and systolic blood pressure from above 155 mmHg to below 140 mmHg. Ninety‐five (n= 71) percent of participants had maintained their glucose level within the 90 mg/dL to 150 mg/dL range with a mean reduction of 57.86 mg/dL in one year. The hardest thing for families was the glucose self‐monitoring. Case studies suggested that open‐minded active listening and persistence formed the basis for developing a culturally sensitive community‐based self management program for chronic diseases. Collaboration among the community, public health nurses, and diabetes nurse educators facilitated the process of community education and health promotion.
Association between HLA‐B*1502 Allele and Antiepileptic Drug‐Induced Cutaneous Reactions in Han Chinese
Authors: Man Celeste B.L. , Kwan Patrick , Baum Larry , Yu Evelyn , Lau K.M. , Cheng Alice S.H. , Ng Margaret H.L.
Published: May 2007

Summary: A previous study conducted in Taiwan found a 100% association between HLA‐B*1502 allele and carbamazepine‐induced Stevens‐Johnson syndrome (SJS) in Han Chinese subjects, with an extremely high odds ratio compared with carbamazepine‐tolerant subjects (odds ratio = 2,504). We examined this association in 24 Hong Kong Han Chinese subjects who had cutaneous adverse reactions induced by different antiepileptic drugs (AEDs). They were matched with 48 AED‐tolerant controls. HLA‐B*1502 was associated with severe cutaneous reactions (SCR) induced by AEDs, which included carbamazepine, phenytoin, and lamotrigine (p = 0.001, odds ratio = 17.6), but was not associated with maculopapular exanthema (MPE) (p = 0.32). Further studies in larger samples of ethnically matched subjects should be conducted to confirm the findings. Identification of genetic polymorphisms predisposing to development of AED‐induced SCR offers the possibility of avoiding these high‐risk drugs in genetically susceptible individuals.
Staphylococcus epidermidis forms biofilms under simulated platelet storage conditions
Authors: Greco Carey , Martincic Irene , Gusinjac Arjeta , Kalab Miloslav , Yang Ann‐Fook , Ramírez‐Arcos Sandra
Published: May 2007

BACKGROUND: Staphylococcus epidermidis grows slowly in platelet (PLT) preparations compared to other bacteria, presenting the possibility of missed detection by routine screening. S. epidermidis is a leading cause of nosocomial sepsis, with virulence residing in its ability to establish chronic infections through production of slime layers, or biofilms, on biomedical devices. This study aims to establish biofilm formation (BF) as a mode of growth by S. epidermidis in PLT preparations.

STUDY DESIGN AND METHODS: Biofilm‐positive (BFpos) and ‐negative (BFneg) S. epidermidis strains were grown in whole blood–derived PLTs (WBDPs) and in glucose‐rich medium (TSBg). An assay for BF was adapted for cultures grown in WBDPs or filtered WBDPs in polystyrene culture plates. Bacterial attachment to polyvinylchloride PLT bags and PLTs was examined by scanning electron microscopy.

RESULTS: Both strains display similar growth profiles in WBDPs and TSBg. Unexpectedly, evidence of BF was observed on PLT bags and on PLTs directly, not only by the BFpos strain but also by the BFneg strain. The BFpos strain displayed greater plastic adherence than the BFneg strain in WBDPs (p  < 0.05). BF by the BFneg strain was approximately 10‐fold greater in WBDPs compared to TSBg (p  < 0.05), likely by use of PLTs as a scaffold. Furthermore, BF by S. epidermidis was significantly decreased when PLT concentration was reduced 1000‐fold.

CONCLUSIONS: S. epidermidis forms biofilms on PLT aggregates and on PLT bags under PLT storage conditions. Our results demonstrate that the PLT storage environment can promote a BF growth mechanism for contaminant bacteria.
Risk factors for hepatitis C virus infection among blood donors in Israel: a case‐control study between native Israelis and immigrants from the former Soviet Union
Authors: Kerzman Hana , Green Manfred S. , Shinar Eilat
Published: May 2007

BACKGROUND: The annual hepatitis C virus (HCV) seropositivity prevalence among blood donors (BDs) in Israel is 0.1 percent. Although only 10 percent of the BD population are immigrants from the former Soviet Union (FSUIs), they represent 80 percent of the HCV‐seropositive cases. This study aimed to identify HCV risk factors among Native Israeli (NI) and FSUI BDs, to determine if specific interventions are needed.

STUDY DESIGN AND METHODS: Two case‐control studies were designed, interviewing 178 HCV‐positive cases (128 FSUIs, 50 NIs) and 256 HCV‐negative controls (128 FSUIs, 128 NIs). All participants were volunteer BDs of Magen David Adom (MDA) Blood Services.

RESULTS: A total of 434 BDs of 985 mailed letters consented to be interviewed (44% response rate), without differences in compliance between the study populations. In both, intravenous drug use (IVDU) was the strongest HCV seropositivity–associated risk factor. After IVDU adjustment, important risk factors were age, blood transfusion before 1990, first‐time donation, and not practicing teeth cleaning. Close contact with people at risk for HCV (odds ratio [OR], 7.2; 95% confidence interval [CI], 1.9‐27.8) and surgery (OR, 7.3; 95% CI, 1.6‐34.4) were strong risk factors among NIs, whereas gum surgery (OR, 7.6; 95% CI, 1.1‐52.3), hospitalization without surgery (OR, 2.6; 95% CI, 1.1‐6.5), and therapy in injection form (OR, 4.9; 95% CI, 2.4‐10.2) were merely found among FSUIs, probably resulting from inadequate aseptic conditions. The ORs for age, gum surgery, contact index, and first blood donation differed significantly between the two populations.

CONCLUSION: Although the strength of risk factors for HCV differs between Israeli and immigrant BDs, most factors studied did not differ between the groups. Therefore, changes in screening of all BDs are considered.
Storage‐dependent remodeling of the red blood cell membrane is associated with increased immunoglobulin G binding, lipid raft rearrangement, and caspase activation
Authors: Kriebardis Anastasios G. , Antonelou Marianna H. , Stamoulis Konstantinos E. , Economou‐Petersen Effrosini , Margaritis Lukas H. , Papassideri Issidora S.
Published: May 2007

BACKGROUND: The elucidation of the storage lesion is important for the improvement of red blood cell (RBC) storage. Ex vivo storage is also a model system for studying cell‐signaling events in the senescence and programmed cell death of RBCs. The membrane hosts critical steps in these mechanisms and undergoes widespread remodeling over the storage period.

STUDY DESIGN AND METHODS: Fresh and CPDA‐stored RBCs from 21 blood donors were evaluated as whole cells, membrane ghosts, and cytoskeletons by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, immunoblotting, immunofluorescence microscopy, and in situ assays. Band 3 content, immunoglobulin G (IgG) content, specific protein movement to and from the membrane, and caspase system activation were measured.

RESULTS: During storage, Band 3 protein was aggregated and its content decreased as did the content of several lipid raft–related proteins. IgG binding to the membrane increased. Sorcin and synexin moved from the cytosol to the membrane, stomatin and flotillins left the membrane, the Fas protein was oligomerized, and caspase was activated.

CONCLUSION: The remodeling of the RBC membrane during storage includes loss and oxidative cross‐linking of Band 3 as well as IgG binding. This process occurs with lipid raft development and loss and is probably driven by caspase activation. Oxidative injury appears to be an important driver of RBC aging during storage.
Arnsdorfs Paradox
Authors: ARNSDORF MORTON F.
Published: May 2007

Arnsdorf's Paradox is that the multiplicities, discontinuities, dynamic interactions, and other complexities that exist in and among the determinants of cardiac excitability should give rise to unpredictably complex behavior, yet electrophysiological events usually are coordinated sufficiently to produce predictable outcomes. Experimental work is discussed in which a complex electrophysiological matrix consisting of active and passive cellular properties that are responsible for overall excitability that is maintained in a dynamic equilibrium by complex feedback systems give way to disequilibrium and seems to self‐organize into a new equilibrium. There must be some order in this seeming chaos. Resolution of this Paradox means that one or another entrenched scientific prejudice must be modified. My Paradox arose through an erroneous premise that complexity led only to further complexity. As some of our experimental work suggests, however, complex systems may behave or may be encouraged to behave quite simply and predictably; and in this exists the resolution of the Paradox. This view has scientific and clinical implications that are briefly discussed.
The Cardiac Arrhythmia Suppression Trial: How Has it Impacted on Contemporary Arrhythmia Management?
Authors: KOWEY PETER R. , MARINCHAK ROGER A. , RIALS SETH J.
Published: May 2007

Implications of the Cardiac Arrhythmia Suppression Trial. A most important issue in cardiology practice has been when and how to treat asymptomatic patients with ventricular arrhythmia. This is a particularly thorny problem, since the presence of complex ventricular ectopy is an independent risk variable in patients with a variety of forms of heart disease. The Cardiac Arrhythmia Suppression Trial (CAST) was designed to answer the question of whether or not abolition of ventricular premature depolarizations, in those who had had a myocardial infarction, would confer any substantial benefit, especially in terms of a mortality reduction. Unfortunately, that question has not yet been answered, but the preliminary results of the CAST has had a major impact on physicians, patients, the scientific community, industry, and regulatory agencies. This article reviews the implications of the CAST and describe how it has affected the contemporary management of patients with cardiac arrhythmia. (J Cardiovasc Electrophysiol, Vol. 1, pp. 457–463, October 1990)
Molecular Basis for Arrhythmias: Role of Two Nonsarcolemmal Ion Channels
Authors: PRESSLER MILTON L. , RARDON DAVID P.
Published: May 2007

Molecular Mechanisms for Arrhythmias. Ventricular tachycardia/fibrillation and sudden cardiac death occur frequently following myocardial ischemia or infarction. The recent Cardiac Arrhythmia Suppression Trial (CAST Study) found that patients treated with the Na‐channel antagonists encainide and flecainide suffered increased mortality over placebo. This unexpected result has dampened enthusiasm for treatment of asymptomatic ventricular arrhythmias and more subtly suggests a need for review of current strategies for analysis and treatment of cardiac arrhythmias. This article focuses on two nonsarcolemmal ion channels that may be involved in certain types of ventricular arrhythmias: the gap junction channel and the Ca2+‐release channel of sarcoplasmic reticulum (SR). Gap junctions enable conduction of the cardiac impulse from cell‐to‐cell and may be involved in reentrant arrhythmias. SR Ca2+‐release channels regulate the level of cytosolic Ca2+ during initiation of contraction and seem to be the basis for triggered activity. Gap junction and SR Ca2+‐release channels, though structurally dissimilar molecules, share certain functional and gating characteristics. In different ways, both channels couple the electrical response to the mechanical response. Furthermore, dysfunction of gap junction channels and/or SR Ca2+‐release channels may underlie the development of arrhythmias in postischemic cells. Classification of arrhythmias on the basis of which channel(s) is principally involved might expedite the development of new drugs targeted at functional regions of the chan‐nel(s). Ultimately, pharmacotherapy of arrhythmias directed at the molecules responsible for the electrical dysfunction may replace the empirical approach that dominates current cardiology practice. (J Cardiovasc Electrophysiol, Vol. 1, pp. 464–480, October 1990)
Manifest Fast and Slow Pathway Conduction Patterns and Reentry in a Patient with Dual AV Nodal Physiology
Authors: ELIZARI MARCELO V. , SANCHEZ RUBEN A. , CHIALE PABLO A.
Published: May 2007

Manifest Fast and Slow AV Nodal Conduction Patterns and Reentry. A 52‐year‐old woman with paroxysmal supraventricular tachycardias (PST) showed short and long PR intervals during sinus rhythm. Repetitive episodes of PST due to simultaneous anterograde conduction through fast and slow conduction pathways (one P‐two QRS) were recorded. A self‐limited episode of non‐paroxysmal AV nodal reentry with anterograde slow and retrograde fast pathway conduction was initiated by a single atrial premature beat. Each pathway depicted distinct refractory periods, conduction velocities, unidirectional block, and Wenckebach‐type block suggesting the possibility of a well‐defined anatomical substratum.
Prevention of Spontaneous Sustained Ventricular Tachycardia in the Postinfarction Dog by Left Stellate Ganglionectomy
Authors: PATTERSON EUGENE , SCHERLAG BENJAMIN J. , LAZZARA RALPH
Published: May 2007

Suppression of Sustained VT by Left Stellectomy. Holter monitoring and ventricular pacing were used to examine control, right stellate ganglionectomy, and left stellate ganglionectomy treatment groups, 6‐24 hours after left anterior descending coronary artery ligation in dogs. In nine of 27 controls (33%), spontaneous ventricular triplets (358 ± 8 beats/min) initiated sustained monomorphic ventricular tachycardia (386 ± 16 beats/min), followed by ventricular fibrillation at 12.6 ± 1.4 hours. Ventricular pacing produced sustained monomorphic ventricular tachycardia in 13 of 18 survivors (73%) at 24 hours. Left but not right stellectomy performed 15 minutes before coronary artery ligation reduced the incidence of spontaneous sustained monomorphic ventricular tachycardia (2 of 27, 7%, P = 0.06; 7 of 27, 26%, P = 0.50, respectively) and reduced the maximal ventricular triplet rate (332 ± 12, P <0.05 and 358 ± 10 beats/min, respectively, P = NS vs control). Neither left nor right stellectomy altered the incidence of ventricular triplets during the 6‐24 hour period (153 ± 58 and 222 ± 55/hour, respectively, vs control, 177 ± 59/hour, P = NS) nor prevented pacing‐induced sustained monomorphic ventricular tachycardia in the survivors at 24 hours (20 of 24, 75%; and 16 of 20, 80%, P = NS). The data demonstrate that left but not right stellectomy reduces spontaneous sustained ventricular tachycardia and ventricular fibrillation during the 6‐24 hour period following coronary artery ligation in the dog. Left stellectomy reduces the triggers for sustained monomorphic ventricular tachycardia (rapid ventricular triplets) without altering the underlying reentrant substrate for sustained ventricular tachycardia.
Cardiac Output, Stroke Volume, and Pacing Rate: A Review of the Literature and a Proposed Technique for Selection of the Optimum Pacing Rate for an Exercise Responsive Pacemaker
Authors: GEDDES L. A. , WESSALE J.L.
Published: May 2007

Cardiac Output and Pacing Rate.
Introduction: The purpose of this report is to determine the optimal pacing rate for an exercising patient. Methods and Results: From a review of the literature and from our own animal studies, the relationship between cardiac output and pacing rate and that between stroke volume and pacing rate are examined in resting and exercising animal and human subjects. With an adequately wide range of pacing rates, there exists a three‐phase relationship between cardiac output and pacing rate. Starting with a low pacing pacing rate, an increase in pacing results in an increase in cardaac output (phase 1), then little change in cardiac output (phase 2), after which there is a decrease in cardiac output (phase 3). However, the relationship between stroke volume and pacing rate does not typically exhibit characteristics that allow identification of the three phases. In resting subjects with impaired ventricles and in exercising subjects, phase 2 is narrow or absent, the cardiac output increasing, then decreasing with an increase in pacing rate. From the experimental data reviewed herein, a technique is proposed for identifying the starting point in selecting the best pacing rate for resting and exercising subjects. The technique relies on identification of the transitions in the three‐phase relationship between cardiac output and pacing rate. Conclusion: The best resting pacing rate is at the lower end of phase 2. A tentative first‐choice exercise rate is at the middle of the resting phase 2 region. However, a change in cardiac output with a change in pacing rate will allow refinement of this first‐choice exercise pacing rate.
The Effects of K+ on Anisotropic Conduction in Sheets of Perfused Rabbit Ventricular Epicardium
Authors: BOERSMA LUCAS , BRUGADA JOSEP , SCHALIJ MARTIN JAN , KIRCHHOF CHARLES , ALLESSIE MAURITS
Published: May 2007

Potassium and Anisotropy. Introduction: The purpose of this study was to investigate the effects of potassium on anisotropic conduction in rabbit ventricles. Methods and Results: In Langendorff perfused rabbit hearts, a two‐dimensional epicardial layer of anisotropic myocardium was created by cryodestruction of the endocardial four fifths of the left ventricle. The heart was paced at 0.5 Hz and the epicardial spread of activation was recorded with a high‐resolution mapping electrode (240 points). In ten experiments, we studied the effects of stepwise increased concentrations of extracellular potassium on epicardial conduction, longitudinal and transverse to the fiber direction. At 6.2 mM of K+, longitudinal conduction velocity (θL) was 61 ± 6.2 and transverse conduction velocity (θT) 25 ± 4.6 cm/sec with a ratio θL/θT of 2.6. At a high concentration of 12.5 ± 1.1 mM, conduction slowed down to 29 ± 6.0 and 11 ± 4.4 cm/sec, respectively, with a slightly increased ratio of 3.2 (NS). The amount of depression of θL and θT varied considerably from experiment to experiment and from region to region. On the average, no statistical difference in the depression of conduction velocity in relation to the fiber orientation was found. At K + concentrations of more than 12.5 ± 1.1 mM, local conduction was seriously impaired at various sites. Lines of functional conduction block appeared in longitudinal and transverse direction. Conclusion: We conclude that during slow heart rates, depression of the fast sodium channels by high extracellular K + causes no detectable differential effects on conduction velocity or on occurrence of conduction block, longitudinal or transverse to the general fiber orientation.
Determinants of Lesion Size During Radiofrequency Catheter Ablation: The Role of Electrode‐Tissue Contact Pressure and Duration of Energy Delivery
Authors: HAINES DAVID E.
Published: May 2007

Determinants of Radiofrequency Lesion Size. Introduction: Radiofrequency (RF) catheter ablation is a promising modality in the management of cardiac arrhythmias, but the optimum protocol for energy delivery has not yet been determined. The purpose of this study was to examine the effects of varying electrode‐tissue contact pressure and varying duration of RF energy delivery on the size of the resultant lesion in an in vitro model of isolated perfused and superfused canine myocardium. Methods and Results: RF power (500 kHz) was delivered through the tip of a specially‐designed thermistor‐tipped 1.6‐mm diameter electrode mounted on an adjustable fulcrum so that contact force could be varied. RF power was adjusted to maintain a constant electrode‐tissue interface temperature of 80°C during lesion production. Seventy‐nine lesions were created with a 90‐second RF energy delivery, and a contact force that was varied between 0 and 400 newtons (N) (0‐41 g). Lesions produced with a small contact force (10 N) were significantly larger than those with a contact force of zero (width 5.5 mm vs 3.8 mm, P <0.0002), but not significantly different from those produced with the maximum contact force of 400 N (width 6.5 mm, P = NS). However, the greater contact force significantly decreased the power required to maintain a constant electrode‐tissue interface temperature. Ninety‐six lesions were then created using a constant contact force, but duration of energy delivery was varied from 10 to 600 seconds. Lesion size grew monoexponentially with time. The t1/2 of lesion growth was 7.6 and 9.6 seconds for depth and width, respectively. Conclusion: Thus, close electrode‐tissue contact is essential for adequate lesion formation during RF ablation of myocardium, but increasing contact force does not significantly increase lesion size if power is adjusted to maintain a constant electrode‐tissue interface temperature. In order to approach steady‐state and maximize lesion size, duration of RF energy delivery should be at least 40 seconds.
Electrophysiologic Evidence for Spinal Pathways for Cardiac Reflexes Initiated by Small Somatic Afferent Fibers
Authors: WURSTER ROBERT D. , GEIS G. STEVEN
Published: May 2007

Spinal Pathways for Somatocardiac Reflexes. Small, somatic afferent fibers, among which mediate painful responses, have important influences on the functions of the heart and vasculature by reflexly controlling autonomic nervous system activity. These reflexes are largely conducted by ascending spinal pathways to the brainstem. The spinal pathways mediating somatosympathetic reflexes are reviewed and compared to those involved in somatovagal reflexes controlling the heart. In seven chloralose anesthetized cats, single unit activity was recorded from cardiac vagal preganglionic fibers. Supramaximal, electrical stimulation of the peroneal nerve inhibited the excitatory influences from electrical stimulation of the carotid sinus nerve. From spinal lesion studies, these inhibitory influences are conducted through ascending, bilateral, spinal pathways in the dorsolateral sulcus area near the dorsal root entry zone. Following these lesions, peroneal nerve stimulation produces vagoexcitatory responses. Thus, similar to reflex effects on sympathetic activity to the heart and vasculature, somatic afferents can excite or inhibit vagal control of the heart, although the directional changes are the reciprocal to those of the sympathetic responses. These somatoautonomic reflex responses involve pathways that ascend in the dorsolateral funiculus and sulcus areas of the cat spinal cord.
Interactions Between Cardiovascular and Pain Modulatory Systems: Physiological and Pathophysiological Implications
Authors: MAIXNER WILLIAM
Published: May 2007

Cardiovascular and Pain Regulatory Systems.Several recent findings provide evidence that cardiovascular and pain regulatory systems are interactive. The physiological responses to acute pain are discussed and hypothetical organizational models that explain how cardiovascular and pain regulatory systems interact are proposed. The adaptive value of interactions between cardiovascular and pain regulatory systems is discussed. It is proposed that maladaptive cardiovascular‐somatosensory interactions may contribute to several cardiovascular disorders such as essential hypertension, asymptomatic myocardial ischemia, and life‐threatening cardiac arrhythmias.
Interactions Between Mental Stress, Ischemia, and Coronary Artery Disease
Authors: YEUNG ALAN C. , GANZ PETER , SELWYN ANDREW P.
Published: May 2007

Mental Stress and Coronary Vasomotion. Coronary artery disease often presents late in its course with adverse events like myocardial infarction and sudden death. One of the earlier manifestations of the disease is transient myocardial ischemia. It is clear that physical and mental stress can precipitate ischemic episodes during daily life. Through studies done in the cardiac catheterization laboratory, we found evidence suggesting that mental stress causes an increase in oxygen demand and a decrease in blood supply by causing vasoconstriction of the atherosclerotic epicardial coronary arteries. Local factors like endothelial dilator function may play a significant role in the vasomotor response to mental stress.
A Comparative Study of Intracoronary Iced Saline Versus Intracoronary Antiarrhythmic Drugs to Identify the Ventricular Tachycardia‐Related Artery
Authors: STRICKBERGER S. ADAM , OKISHIGE KAORU , FRIEDMAN PETER L.
Published: May 2007

Identifying the Tachycardia‐Related Coronary Artery. Introduction: Transcatheter chemical ablation is a new treatment option for patients with ventricular tachycardia. Availability of a safe, simple, and sensitive method to identify the ventricular tachycardia‐related artery is required for successful intracoronary chemical ablation for ventricular tachycardia. The purpose of this study was to compare bolus intracoronary iced saline injection to bolus intracoronary antiarrhythmic drug injection as methods for identifying the ventricular tachycardia‐related coronary artery.

Methods and Results: Patient selection was limited to eight individuals with recurrent sustained monomorphic ventricular tachycardia, coronary artery disease, remote myocardial infarction, and in whom programmed stimulation could reproducihiy induce the clinical arrhythmia. An infusion catheter was positioned in the putative ventricular tachycardia‐related artery and ventricular tachycardia was provoked hy programmed stimulation. In four patients the putative ventricular tachycardia‐related artery was a patent infarct‐related vessel and in the other four patients was a vessel supplying collateral flow to an occluded infarct‐related artery. The effects of selective intracoronary iced saline bolus injection (10 mL), and then of selective intracoronary bolus antiarrhythmic drug injection (2.5 mg lidocaine in one patient, procainamide 1.0–9.0 mg in seven patients) were observed. Bolus intracoronary iced saline injection did not alter ventricular tachycardia in any patient. Bolus intracoronary antiarrhythmic drug injection, however, led to ventricular tachycardia cycle length prolongation in two patients and arrhythmia termination in four patients. In two of these individuals, infusion of ethanol into the tachycardia‐related vessel previously identified by intracoronary drug injection resulted in ablation of the ventricular tachycardia.

Conclusions: In the present study, selective intracoronary antiarrhythmic drug injection appeared to be more effective than intracoronary iced saline for identifying the ventricular Uchycardia‐related coronary artery, (J Cardiovasc Electrophysiol, Vol. 3, pp. 199–208 June 1992)
The Electrogenic Sodium/Potassium Pump and Passive Sodium Influx of Isolated Guinea Pig Ventricular Myocytes
Authors: LEVI ALLAN J.
Published: May 2007

Electrogenic Sodium/Potassium Pump in Ventricular Myocytes. Introduction: The membrane current generated by the sodium/potassium pump was measured in ventricular myocytes isolated from guinea pig hearts.

Methods and Results: Cells were impaled with microelectrodes to minimize dialysis of the intracellular milieu and thus maintain normal physiological conditions. To selectively record pump current, it was necessary to suppress potassium currents with external barium and to buffer intracellular calcium with a calcium chelator. Exposure to potassium‐free solution was used to inhibit the sodium/potassium (Na/K) pump and load the cell with intracellular sodium (Na i). When the pump was subsequently reactivated by replacing extracellular potassium, there was a sharp increase of a transient outward membrane current, which declined back to control with a time constant of 50.7 ±12.9 seconds (mean ± SD, n = 11). The increase of outward membrane current became larger after longer periods of potassium removal and was abolished by the pump inhibitor strophanthidin. These features show that the transient outward current was generated by the Na/K pump. The pump current of quiescent myocytes was assessed by two different methods. First, it was evaluated directly by measuring the loss of outward pump current upon exposure to a maximal blocking dose of strophanthidin. The loss of outward current was 20.3 ± 5.5 pA (n = 11), which is equivalent to a pump current density of 0.164 /μA/cm2. The second method was to estimate passive Na influx into quiescent myocytes, by measuring the charge extruded by the pump after a period of potassium removal. The charge extruded during recovery reflects the magnitude of Na i accumulation during potassium removal. Passive Na influx was found to be 4.58 ± 2.4 pmol/cm2 per second. If passive Na influx is normally balanced fully by Na extrusion on the Na/K pump, this will result in an average pump current of 18.0 pA (equivalent to a pump current density of 0.147 μA/cm2). Thus, although the two methods for estimating the pump current of quiescent myocytes were different, their results agreed well. A pump current of 20 pA will contribute only about 0.4 mV to the resting potential of ventricular myocytes. This conclusion was confirmed experimentally by showing that pump inhibition depolarized the resting potential of myocytes by only 0.45 ± 0.05mV(n = 10).

Conclusion: An important finding of this study is that the electrogenic Na/K pump makes a much lower contribution to the resting potential of ventricular muscle than was previously supposed. (J Cardiovasc Electrophysiol, Vol. 3, pp. 225–238, June 1992)
Amiodarone: Pharmacology, Clinical Actions, and Relationships Between Them
Authors: NATTEL STANLEY , TALAJIC MARIO , FERMINI BERNARD , ROY DENIS
Published: May 2007

Amiodarone Therapy. Amiodarone is a unique compound, with actions of all four antiarrhythmic drug classes. It has been used effectively to treat a broad range of ventricular and supraventricular arrhythmias. As a result of amiodarone's enormous volume of distribution and slow disposition kinetics, gradual accumulation occurs during maintenance dosing, and the drug's clinical action can be produced more rapidly with the use of an early loading period. Similarly, plasma concentrations and effects of amiodarone decrease slowly after drug discontinuation. There is a clinical impression that amiodarone is superior over other agents for a wide variety of arrhythmias, but this remains unproven. Because of uncertainty regarding amiodarone's efficacy compared to alternative therapies, and amiodarone's important potential for causing cardiac, pulmonary, hepatic, central nervous system, ocular, thyroid, and cutaneous adverse effects, amiodarone's precise role in antiarrhythmic therapy remains to be established. (J Cardiovasc Electrophysiol, Vol. 3, pp. 266–280, June 1992)
Ectopic Ventricular Beats Originating in Ischemically‐Injured Left Ventricular Epicardium, 24 Hours Following Coronary Artery Occlusion in the Dog
Authors: PATTERSON EUGENE , SCHERLAG BENJAMIN J. , LAZZARA RALPH
Published: May 2007

Epicardial Ectopics. Introduction: Ventricular ectopic beats demonstrating: (1) depolarization in ischemically‐injured anterior epicardium preceding His‐Purkinje activation by more than 25 msec; (2) initial delta waves on the anterior chest leads of the surface ECG coincident with presystolic epicardial activation; and (3) a left bundle branch block morphology were observed in 46 of 256 anesthetized dogs evaluated 18–24 hours following anterior descending coronary artery occlusion.

Methods and Results: In 18 experiments, endocardial and epicardial recordings, and signal‐averaged recordings from the left ventricle were used to determine the earliest activation time/site for epicardial ectopic beats. In these ventricular ectopic beats, early epicardial activation was coupled to the preceding beat by a constant, fixed coupling interval. Electrical activity during the interectopic interval was not detected with composite or multiple bipolar recordings, or with signal averaging from the heart. The mean coupling interval was prolonged by lidocaine from 385 ± 24to 409 ± 45 msec (P < 0.01), and was decreased by epinephrine (364 ± 7 msec) and D‐600 (324 ± 32 msec)(P < 0.05). Spontaneous ventricular beats of epicardial origin could be reversibly suppressed by epicardial lidocaine administration or permanently suppressed with intracoronary latex injection, eliminating presystolic potentials. Histologic examination of the epicardium revealed surviving tissue bands (0.5–2.0 mm) distributed throughout transmural infarcted epicardium.

Conclusion: The present experiments demonstrate constant‐coupled ectopic ventricular beats of epicardial origin, 18–24 hours following myocardial infarction. The ventricular ectopic beats may result from abnormal automaticity or electrotonic excitation from an initiating beat across an unexcitable gap with slow conduction from the “site of origin’ to reactivate the left ventricle. (JCardiovasc Electrophysiol, Vol. 3, pp. 315–333, August 1992)
The Cardiac Pacemaker Current if
Authors: DiFRANCESCO DARIO , ZAZA ANTONIO
Published: May 2007

Pacemaker Current if. Since the hyperpolarization‐activated current, if, was originally associated with the diastolic depolarization phase of action potential in the sinoatrial (SA) node in 1979, its central role in the generation and control of pacemaker activity has become increasingly clear through a series of experimental findings, some of which have substantially modified the pre‐existing theories of cardiac pacemaking and its modulation by the autonomic transmitters. Thus, the pacemaker current of Purkinje fibers, formerly described as a deactivating pure potassium (K) current, was found to be in fact, like the nodal if, inward and activating on hyperpolarization. Furthermore, in SA node cells, as well as mediating rhythm acceleration induced by catecholamines, if was found to underlie the slowing effect of low acetylcholine (ACh) concentrations, in contrast with the generally accepted hypothesis that activation of a K conductance is the main process responsible for cardiac slowing. A final, atypical property of if recently demonstrated concerns the activating action exerted on if by intracellular cAMP. Unlike that on other voltage‐gated, cAMP‐modulated cardiac channels, this action is independent of phosphorylation and involves a direct binding of cAMP to if channels. (J Cardiovasc Electrophysiol, Vol. 3, pp. 334–344, August 1992)
Current Status of Lasers for Arrhythmia Ablation
Authors: SVENSON ROBERT H. , LITTMANN LASZLO , SPLINTER ROBERT , TATSIS GEORGE P. , CHUANG CHI HUI
Published: May 2007

Current Status of Lasers for Arrhythmia Ablation. Wavelength specific effects and mode of laser operation allow either photocoagulation or tissue removal as a means of approaching arrhythmia ablation. Successful intraoperative ablation of ventricular tachycardias has been performed with the Nd: YAG laser (photocoagulation) and argon laser (tissue vaporization). The argon laser has been used intraoperatively for transection of accessory pathways. Experimental studies indicate a strong theoretical potential for Nd:YAG laser catheter ablation of ventricular tachycardia. Laser energy has been used experimentally to evaluate the possibility of AV junctional ablation/modification and accessory pathway ablation. Adaption of laser energy to effective catheter systems for arrhythmia ablation requires solutions to problems inherent in all catheter systems and some unique to laser energy. (J Cardiovasc Electrophysiol, Vol. 3, pp. 345–353, August 1992)