«ATTENTIONAL BIAS IN PATIENTS WITH IMPLANTABLE CARDIOVERTER DEFIBRILLATORS: EXAMINING MECHANISMS OF HYPERVIGILENCE AND ANXIETY By NEHA K. DIXIT A ...»
ATTENTIONAL BIAS IN PATIENTS WITH IMPLANTABLE CARDIOVERTER
DEFIBRILLATORS: EXAMINING MECHANISMS OF HYPERVIGILENCE AND
NEHA K. DIXIT
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA© 2008 Neha Dixit To my amazing grandparents whose value for learning, education and zestful spirit of adventure
forged the way for higher education in the generations to come. And to my own parents and husband:
Your never ending support and love through this journey will always be with me. I am eternally grateful for each of you.
TABLE OF CONTENTSpage ACKNOWLEDGMENTS
LIST OF TABLES
LIST OF FIGURES
CHAPTER 1 INTRODUCTION
Overview and Study Aims
Background and Significance
Psychosocial Effects of ICD Implantation
Anxiety and the ICD Patient
Arrhythmias and Hypervigilance
Anxiety as Precipitant to Shock
Attentional Bias and Emotion
Experimental Paradigms Examining Attentional Bias
Evidence of Attentional Bias in Anxiety Disorders
2 EXPERIMENTAL DESIGN AND METHODS
General Health-Related Quality of Life
3 DATA ANALYSIS AND RESULTS
Dot Probe Task
Reaction Time Data
Cue Word Valence and Arousal Ratings
Cue Word Valence Ratings
Cue Word Arousal Ratings
Effect of Shock on Dot Probe Task
Shock and Reaction Time
Shock and Error Rates
Evidence of Attentional Bias
Cohort Effects on Task
Differences in Methodology
APPENDIX: WORD STIMULI USED IN TASK
2-1 Mean (+standard deviation) demographic and psychological test data for VF and AF patients.
A-1 Word stimuli used in task
2-1 Example of a typical incongruent, clinically relevant trial.
3-1 Dot-probe task reaction times for VF (ICD) and AF (control) patients.
3-2 Dot-probe task error rates for VF (ICD) and AF (control) patients.
3-3 Subjective ratings for cue-word valence.
3-4 Subjective ratings for cue-word arousal.
3-5 Dot-probe task reaction times for no shock (ICD) and shocked (ICD) patients................43 3-6 Dot-probe task error rates for no shock (ICD) and shocked (ICD) patients.
3-7 Average attentional bias scores (incongruent-congruent). Negative scores indicate decreased bias.
Chair: William M. Perlstein Cochair: Samuel F. Sears Major: Psychology Symptoms of anxiety and hypervigilance are prevalent in patients with arrhythmias, particularly in patients with life threatening arrhythmias such as ventricular fibrillation (VF).
The treatment of choice for patients with VF is implantation of an implantable cardioverter defibrillator (ICD) which shocks patients out of life threatening arrhythmias and places them at risk for shock specific anxiety secondary to living with their device. Literature examining affective influences on attentional processing suggests that people with high levels of anxiety have biased attention towards threatening information, such that they have difficulty disengaging attention from negative or threatening stimuli. Using a modified emotional dot-probe task, we examined attentional bias in patients with ICDs comparing them to patients with atrial fibrillation (AF). Contrary to predictions, ICD patients did exhibit attentional bias towards clinically relevant information compared to AF controls, and levels of state and trait anxiety did not influence the magnitude of attentional bias in either group. ICD patients demonstrated higher levels of trait anxiety compared to AF patients as well as worse physical functioning.
Additionally, results demonstrate efficacy of affective stimuli, with ICD patients rating clinical words as more unpleasant than AF controls. Overall, results suggest that this paradigm must be examined and potentially modified in greater detail to elucidate the influence of affective cue words on attentional bias in the arrhythmia population.
Each year, approximately 350,000 Americans experience sudden cardiac death (SCD) related to the occurrence of cardiac arrhythmias, including ventricular fibrillation (VF) and ventricular tachycardia (VT; American Heart Association, 2004). The Implantable cardioverter defibrillator (ICD) is the treatment of choice for ventricular cardiac arrhythmias (Antiarrhythmic versus Implantable Device [AVID] Investigators, 1997; Moss et al., for the Multicenter Automatic Defibrillator Implantation Trial [MADIT] Investigators, 1996), and nearly 60,000 Americans receive an ICD each year. Although the ICD has demonstrated impressive mortality benefits, the device nonetheless presents as a potential instigator of psychological maladjustment in recipients. This is primarily due to the shock mechanism necessary for the device to convert potentially lethal arrhythmias. Significant rates of panic symptoms (Godemann, Butter, Lampe, Linden, Werner, & Behrens, 2004) and avoidance behaviors (Lemon, Edelman, & Kirkness, 2004) have been documented among this population, as have difficulties with depression, anxiety, interpersonal functioning, and stress management (Sears & Conti, 2003).
Researchers have also implicated anxiety about the device and health related anxiety as significant predictors of psychosocial distress (Pauli et. al, 1999; Sears, 1999). Given the high levels of susceptibility for both device related and generalized disease specific anxiety in ICD recipients, it is critical to identify areas of cognitive functioning which may be affected by such distress and may also serve to maintain or exacerbate such distress. Considerable research has shown that selective attention, the ability to attend to and ignore information in the environment, may be a critical cognitive process that is affected by both normal and clinical (i.e., social and specific phobic) anxiety (Compton, 2003). Emotional processing is tightly linked to levels of arousal (Damasio, 1996), such that high levels of arousal (e.g. fear, threat) may enhance attention during a threatening situation and low levels of arousal may allow an individual to ignore relevant information. Patients with cardiac disease, specifically arrhythmias, constantly evaluate their own levels of related threat (Pauli, 1999). The nature of their disease state warrants critical vigilance to symptomatology, adherence to medication regimens, knowledge of health care options and advances, and a host of medical information which may vary throughout the course of living with chronic cardiac disease. Attention or vigilance to medical knowledge and personal health status is important as it keeps arrhythmic patients focused on returning to full functioning. Too much or too little attention to such information can result in diminished physical and mental functioning. Thus, examining the levels of attention to cardiac specific information in ICD recipients (for whom anxiety is directly related to physical symptomatology and device specific characteristics) may give rise to further characterizing and understanding patients’ beliefs and specific fears about their devices and disease state for future interpretation.
The current study aimed to examine cardiac-specific attentional biases in patients living with ICDs. Patients with ICDs provide a unique perspective on the relationship among emotion, attention, and anxiety given the nature of the acquisition of their symptoms. ICD recipients who are psychologically healthy prior to implantation may experience clinical levels of anxiety following ICD implantation and the experience of ICD shock. Examining ICD patients’ ability to disengage attention from shock-related information is critical to their quality of life and psychosocial health. It is important for patients to redirect from negative material (e.g. counting their pulse, catastrophic thoughts) in order for them to retain information provided by physicians and live actively with the benefits of the device and minimize drawback. Previous research has suggested that a variety of anxiety-disordered patients demonstrate attentional biases towards clinically-relevant information (Derryberry & Reed, 1994) and that attention to threatening information is directly related to coping style and functional strategy. Research has demonstrated that patients with adaptive coping strategies are able to disengage better from negative disease specific information than those with maladaptive strategies. Thus, examination of attentional bias for cardiac-related information in ICD recipients could prove useful in tailoring future treatments to these patients.
• Specific Aim 1: To determine if the implantation of an ICD in cardiac patients, the frequency of ICD shock, and generalized state or trait anxiety are associated with specific affectmediated selective attentional biases as measured using a variation of the Dot Probe task.
Based on the literature suggesting attentional bias towards threatening information in individuals with high levels of anxiety (i.e. state) and specific phobias, it is hypothesized that both levels of distress and the presence of at least one ICD shock will contribute to biased performance, reflected by disproportionately slower reaction times under clinically-relevant cued conditions compared to both arrhythmia control patients and non-ICD-related cues.
• Specific Aim 2: To examine if varying levels of state and trait anxiety differentially affect attentional bias in both ICD patients and arrhythmia controls. Evidence suggests that living with an arrhythmia (whether life threatening or not) may increase the extent of ones’ bodily or cardiac-specific vigilance. Additionally, studies of attentional bias in participants with sub-clinical levels of anxiety also show a bias towards threat-relevant information. It is hypothesized that the magnitude of attentional bias to threat will be positively correlated with levels of state, but not trait, anxiety in both groups as demonstrated in previous studies examining attentional biases in otherwise healthy individuals (Fox, Dutton, & Bowles, 2001).
State anxiety has been implicated in attentional bias in anxiety-disordered individuals, whereas trait anxiety has not generally been correlated with indices of bias in similar dot probe paradigms (Mogg & Bradley, 2002).
In sum, the proposed research will examine potential selective-attention biases to cardiacrelated information in patients who have received ICDs. The significance of this research is twofold: 1) it may enhance our understanding of attentional biases in patients who are potentially developing heightening anxiety and concern with bodily symptoms, thereby providing a prospective means by which to study natural anxiety-disorder development, and 2) it may provide insight into treatment of cardiac specific anxiety-related symptoms in patients with ICDs which can potentially improve their quality of life, lead to better adherence to treatment regimens, and improved understanding of their disease process.
The following sections will first describe the prevalence and presentation of psychosocial distress in patients with ICDs and arrhythmias. Then, the use of the dot-probe paradigm to examine attentional bias in a variety of anxiety-disordered individuals will be discussed. Finally, the relationship between ICD placement, shock, anxiety, and attentional bias will be explained, including possible mechanisms for the observed relationship.