Cardiovascular effects of desipramine in children and adults during exercise testing

OBJECTIVE

In light of recent reports of sudden death in children being treated with desipramine (DMI), 3 of which were associated with physical exercise, the authors examined the effects of DMI on exercise in children and adults before and during DMI treatment.

METHOD

Before treatment, 22 subjects (9 children, 13 adults) participated in a graded treadmill exercise test. Outcome measures included exercise tolerance, cardiovascular, and electrocardiographic parameters at progressive intensity levels and serum norepinephrine (NE) levels before and after exercise testing. Subjects were then treated with DMI, titrated to an average DMI dosage of 3 mg/kg, and underwent repeated exercise testing.

RESULTS

DMI treatment was associated with a significant elevation of circulating NE levels in the pre-exercise assessment. Exercise tolerance was not affected by DMI, and blood pressure and heart rate effects were modest. The cardiovascular impact of DMI treatment was similar in children and adults. One 31-year-old subject exhibited a brief episode of ventricular tachycardia associated with exercise during DMI treatment.

CONCLUSIONS

DMI has only minor effects on the cardiovascular response to exercise, and these effects do not appear age-related. However, DMI may increase the risk of exercise-associated arrhythmias in rare individuals.

Cardiac autonomic control buffers blood pressure variability responses to challenge: a psychophysiologic model of coronary artery disease

This article presents a model that identifies effects of blood pressure variability (BPV) as a possible mechanism by which psychological/psychiatric factors and health behaviors confer increased risk of coronary artery disease (CAD) and acute coronary syndromes. Recent research in vascular biology and dynamics of coronary artery blood flow suggests that BPV may have pathogenic effects on the coronary endothelium, plaque formation, and plaque stability. Thus, BPV may be a risk factor for cardiovascular disease independent of mean arterial pressure. The model proposes that autonomic control of the heart exerts a buffering or inhibitory influence on oscillations in blood pressure. Established psychological/behavioral risk factors for CAD, such as depression, hostility, and anxiety, as well as physical deconditioning and aging, are associated with diminished autonomic control of the heart, which may disinhibit pathogenic BPV. Together, these data suggest a coherent, testable psychophysiological model of CAD. In this article, we review these data and make recommendations for research to examine the model.

Multiple metabolic syndrome is associated with lower heart rate variability. The Atherosclerosis Risk in Communities Study

OBJECTIVE

To test at the population level whether people with multiple metabolic syndrome (MMS) disorders have reduced cardiac autonomic activity (CAA).

RESEARCH DESIGN AND METHODS

We examined the association between the level of CAA and MMS disorders, at the degree of clustering and the segregate combination levels, using a random sample of 2,359 men and women aged 45-64 years from the biracial, population-based Atherosclerosis Risk in Communities (ARIC) Study. Supine resting 2-min beat-to-beat heart rate data were collected. High-frequency (HF) (0.15-0.35 Hz) and low-frequency (LF) (0.025-0.15 Hz) spectral powers, the ratio of LF to HF, and the SD of all normal R-R intervals (SDNN) were used as the conventional indices of heart rate variability (HRV) to measure CAA. The MMS disorders included hypertension, type 2 diabetes, and dyslipidemia.

RESULTS

HRV indices were significantly lower in individuals with MMS disorders. The multivariable adjusted mean HF was 0.85 (beat/min)2 in subjects with all three MMS disorders, in contrast to 1.31 (beat/min)2 in subjects without any MMS disorder. At the segregated combination level, the multivariable adjusted means +/- SEM of HF were 1.34 +/- 0.05, 1.16 +/- 0.05, 1.01 +/- 0.17, and 1.34 +/- 0.05 (beat/min)2, respectively, for subjects without any MMS disorder, with hypertension only, with diabetes only, and with dyslipidemia only, and the means +/- SEM of HF were 0.93 +/- 0.04, 0.70 +/- 0.15, and 1.20 +/- 0.05 (beat/min)2, respectively, for subjects with diabetes and hypertension, diabetes and dyslipidemia, and hypertension and dyslipidemia. An increase in fasting insulin of 1 SD was associated with 88% higher odds of having a lower HF. The pattern of associations was similar for LF and SDNN.

CONCLUSIONS

These findings suggest that MMS disorders adversely affect cardiac autonomic control and a reduced cardiac autonomic control may contribute to the increased risk of subsequent cardiovascular events in individuals who exhibit MMS disorders.

Heart period variability and psychopathology in urban boys at risk for delinquency

To examine associations between heart period variability (HPV) and psychopathology in young urban boys at risk for delinquency, a series of 697-11-year-old younger brothers of adjudicated delinquents received a standardized psychiatric evaluation and an assessment of heart period variability (HPV). Psychiatric symptoms were rated in two domains: externalizing and internalizing psychopathology. Continuous measures of both externalizing and internalizing psychopathology were associated with reductions in HPV components related to parasympathetic activity. These associations could not be explained by a number of potentially confounding variables, such as age, ethnicity, social class, body size, or family history of hypertension. Although familial hypertension predicted reduced HPV and externalizing psychopathology, associations between externalizing psychopathology and HPV were independent of familial hypertension. Psychiatric symptoms are associated with reduced HPV in young urban boys at risk for delinquency.

Blood pressure variability responses to tilt are buffered by cardiac autonomic control

Variability in blood pressure (BPV) is influenced by vascular sympathetic drive as well as autonomic control of the heart. Evidence suggests that elimination of cardiac autonomic control, as measured by heart period variability (HPV), produces a reduction in BPV at rest but an increase in BPV during challenge. We recently showed that the BPV response to psychological challenge, which principally produces cardiac parasympathetic withdrawal, was inversely related to the subject's level of cardiac control. In the current study we examined the BPV response to orthostatic tilt, a sympathetic stressor. Subjects were 22 healthy men and women who differed in cardiac control due in part to differences in aerobic capacity. HPV and BPV were measured noninvasively on a beat-to-beat basis. Tilt produced significant increases in heart rate and diastolic blood pressure and a significant decrease in high frequency HPV. As predicted, changes in BPV in response to tilt were inversely related to resting HPV. Results are interpreted in terms of a model of cardiovascular control which holds that BPV originates from feedforward effects of central control of the heart, feedback effects mediated through the baroreflexes, and direct sympathetic vascular effects.

Cardiac autonomic control is inversely related to blood pressure variability responses to psychological challenge

Blood pressure exhibits variability (BPV) at low (0.02- to 0.07-Hz), mid (0.07- to 0.15-Hz)-, and high (0.15- to 0.50-Hz) frequencies. Evidence suggests that BPV responses to challenge are inversely related to cardiac autonomic control. We tested this hypothesis by examining the BPV responses to psychological stressors in 22 normal subjects who differed in cardiac control, operationalized as resting heart period variability (HPV). HPV and BPV were measured noninvasively or a beat-to-beat basis. The stressors produced a significant increase in heart rate and a small but significant increase in diastolic blood pressure. As predicted, the changes in BPV in response to the stressors were inversely related to resting HPV. The results are interpreted in terms of a model of cardiovascular control that holds that BPV originates from feedforward effects of central control of the heart, feedback effects mediated through the baroreflexes, and direct sympathetic vascular effects.

Lorazepam reduces cardiac vagal modulation in normal subjects

Benzodiazepines are frequently administered postmyocardial infarction, but their effect on heart period variability (HPV), a prognostic index of sudden arrhythmogenic death, is unclear. In fact, in both humans and animals, previous studies utilizing acute intravenous doses yielded mixed results. We hypothesized that lorazepam (LZ), by potentiating gamma-aminobutyric acid-A-ergic inhibition of preganglionic vagal neurons projecting to the heart, would reduce cardiac vagal modulation. We therefore tested LZ's effect on HPV over 24 hours of normal physiologic activity in human volunteers in the presence of steady-state LZ. A double-blind, randomized, placebo-controlled study was conducted. Seven healthy subjects received LZ or placebo for 1 week, 1 week taper, then crossed over. Electrocardiogram recordings measured HPV after the administration of drug and placebo for 24 hours. LZ increased mean heart rate by 8% (p < 0.002), decreased the standard deviation of R-R intervals by 9% (p < 0.05), decreased the percent differences between adjacent normal R-R intervals > 50 msec by 30% (p < 0.002), decreased the root-mean-square successive difference by 17% (p < 0.02), and decreased the natural logarithm of high-frequency power by 6% (p < 0.03). The significant heart rate increase and HPV decreases demonstrate vagolytic effects of LZ in healthy subjects during 24 hours of normal physiologic activity.

Continuous time estimation as a behavioural index of human cerebral ischaemia during temporary occlusion of the internal carotid artery

OBJECTIVE

To determine whether a continuous time estimation task during test occlusions of either internal carotid artery would increase the ability to detect the earliest signs of cerebral ischaemia in the anterior circulation.

METHODS

Four patients were involved in real time measurement of their timing accuracy before, during, and after each test occlusion. While under each test condition, patients were instructed to press a mouse button connected to a computer and then to press it again no sooner than 10 seconds from the previous response but no longer than 13 seconds later. While being given automated feedback on accuracy, patients were instructed to continually press the mouse on the target schedule to maximise correct responses until told to stop.

RESULTS

The data showed deterioration of timing accuracy during carotid occlusion (P < 0.05), which always preceded the onset of physical signs and correlated in one patient with the presence of reduced regional cerebral blood flow.

CONCLUSION

Decline of sustained attention under conditions of test balloon occlusion of either internal carotid artery was an indicator of failure to maintain adequate cerebral blood flow to sustain normal neurological function. The demonstration of the behavioural effects of early cerebral ischaemia shows the feasibility of an experimental model for the study of human brain function, and may now make it possible to quantify more precisely the time course of acute ischaemic events.

Long-term outcome in systemic lupus erythematosus membranous glomerulonephritis. Lupus Nephritis Collaborative Study Group

The pathology of membranous glomerulonephritis (MGN) in patients with systemic lupus erythematosus (SLE) may be complicated by superimposed glomerular inflammation and/or necrosis. This retrospective study examined whether various histologic patterns of glomerulonephritis (GN) seen on renal biopsy impact upon the prognosis of these patients. Clinical parameters at the time of biopsy were also studied, to determine which might serve as risk factors associated with renal and patient outcome. On the basis of renal biopsy findings, patients were stratified into three pathological study groups by using the World Health Organization (WHO) classification (11). Thirty-six patients had "pure' SLE MGN without (WHO Va) or with (WHO Vb) mesangial hypercellularity. Fifteen patients had SLE MGN with segmental endocapillary proliferation and/or necrosis in < 50% of glomeruli (WHO Vc < 50%). Twenty-eight patients had SLE MGN with endocapillary proliferation and/or necrosis in > or = 50% of glomeruli (MGN with segmental proliferation and/or necrosis in > 50%, WHO Vc > or = 50%, or MGN with superimposed diffuse endocapillary proliferation, WHO Vd). There were no significant differences in sex, age, or race among patients in the three study groups. There was a trend for increasing serum creatinine concentration, urine protein excretion, and diastolic blood pressure, and decreasing the third component of serum complement (C3) to be associated with increasing glomerular inflammation, and these differences were significant when Vc > or = 50% and Vd was compared with Va and Vb (P < 0.05). The 5- and 10-yr actuarial survival rates without reaching the study outcomes of death or renal replacement therapy for the three study groups were 86, 72, and 49% and 72, 48, and 20% respectively, and the differences between Va and Vb and Vc > 50% and Vd were significant (P < 0.05). SLE MGN has a heterogeneous course and outcome, and this variability is related to the extent and degree of glomerulonephritis seen on renal biopsy. The only clinical factor with an independent risk of reaching a study outcome was elevation of the initial serum creatinine concentration (Cox regression analysis). This predictive value appears to apply only to patients with the most severe forms of glomerulonephritis, suggesting that they may have a different natural history and/or a response to therapy than SLE MGN with less widespread glomerular inflammation and/or necrosis.

Heart rate reactivity and heart period variability throughout the first year after heart transplantation

Heart rate reactivity to mental stress is substantially blunted early after heart transplantation, suggesting that the loss of neural modulation limits the cardiovascular response to mental stress. We tested whether reactivity to mental stress recovers during the first year after heart transplantation. Hemodynamic and respiratory responses to mental arithmetic challenge were studied in 20 heart transplant recipients 3, 6, and 12 months after surgery. A normal comparison group was studied at equivalent intervals. Heart rate reactivity to mental arithmetic was significantly reduced in the cardiac transplant group compared to the normal subjects. This effect persisted up to 1 year after transplantation. Heart period variability in the heart transplant recipients was minimal in all three test sessions. The findings suggest that no functional reinnervation or other compensatory adaptation occurs up to 1 year after heart transplantation.

Relationships between circulating catecholamines and low frequency heart period variability as indices of cardiac sympathetic activity during mental stress

Heart rate increases during psychological stress are the product of cardiac sympathetic activation and parasympathetic withdrawal. Levels of plasma epinephrine (E) and norepinephrine (NE) have a long history as indicators of cardiac adrenergic activity and, accordingly, generally increase in response to psychological challenge. Recently, several investigators have suggested that indices derived from power spectral analysis of heart period variability (HPV) also may provide estimates of cardiac sympathetic nervous system activity. These indices include power in the low frequency band (0.04-0.15 Hz, LF), and the ratio of low to high frequency (0.15-0.50 Hz, HF) power (LF/HF). The relationship between spectral and neurohumoral indices during psychological stress has not been investigated. This issue was addressed by studying spectrally defined measures of HPV and levels of plasma E and NE in 34 normal subjects who participated in a study of responsiveness to a psychologically challenging arithmetic task. Heart rate (HR), LF and HF power, the LF/HF ratio, and blood pressure were measured during the 5-minute baseline and 5-minute task periods. Integrated samples of forearm venous blood were collected for both periods. E and NE were analyzed by high performance liquid chromatography. The task produced significant increases in HR, systolic and diastolic pressures, and NE. Of the 12 Pearson correlation coefficients used to examine the relationships between power spectral measures and catecholamines for the baseline, task, and delta values, none achieved statistical significance, suggesting little relationship between neurohumoral and spectral estimates of cardiac sympathetic activity. We conclude that under conditions of psychological stress, LF power provides no useful information about cardiac sympathetic activity, both because power in this frequency band falls whereas HR rises and because there is no relationship between LF power and plasma NE.

Consistency of heart rate and sympathovagal reactivity across different autonomic contexts

Theories that psychophysiological reactivity constitutes a risk factor for coronary artery disease assume that reactivity is a consistent individual characteristic. We tested this assumption by measuring reactivity to three psychologically challenging tasks performed by 22 healthy subjects across different autonomic contexts produced by positional change. Dependent variables included heart rate (HR), low-frequency (LF; 0.04-0.15 Hz) and high-frequency (HF; 0.15-0.50 Hz) heart period variability, and the LF/HF ratio. HR (r = .44, p < .05) and LF/HF ratio (r = .48, p = .03) reactivity were modestly correlated across the different autonomic contexts, but HF and LF power reactivity were not. These findings suggest that HR reactivity to psychological challenge is a modestly consistent characteristic of individuals, despite differences in autonomic context. Although the same is true of cardiac sympathovagal balance, reactivity of HF and LF power were less consistent.

Efficacy of computerized health risk appraisal as part of a periodic health examination at the worksite

PURPOSE

To evaluate the efficacy of computerized health risk appraisal (HRA) when it is incorporated into a periodic health examination at the worksite.

DESIGN

A randomized, controlled trial comparing change in health behaviors for a 6-month follow-up period was conducted.

SETTING

A large financial services firm in New York City.

SUBJECTS

A total of 161 employees who volunteered for a worksite periodic health examination.

INTERVENTION

All employees received a physician-based history and physical examination, including laboratory tests, and were counseled on the basis of the results. Half the employees were randomly assigned to receive an HRA report with counseling from the 1984 version of the Centers for Disease Control HRA, whereas the other half completed the HRA questionnaire but received no HRA report or counseling.

MEASURES

Blood pressure, cholesterol, and weight were measured by project staff, physical activity and seatbelt use were measured by self-report, and change in computerized appraised age was calculated by the HRA program.

RESULTS

Evaluation of the 90 participants who returned for follow-up revealed a statistically significant improvement in computerized appraised age and physical activity in those who has received the HRA report and counseling compared with those who had not (p < or = .05), and also showed trends toward greater improvement in blood pressure, weight, and seatbelt use.

CONCLUSIONS

Results provide support for the efficacy of HRA when incorporated into a periodic health examination at the worksite.

Temporal stability of heart period variability during a resting baseline and in response to psychological challenge

Central to the psychophysiologic reactivity hypothesis of the etiology of coronary artery disease is the assumption that reactivity is an individual characteristic that is stable over time. Although heart rate (HR) and blood pressure reactivity appear to meet this criterion, temporal stability of cardiac autonomic control as measured by analysis of heart period variability (HPV) has not been assessed. In this study, we tested the stability of HPV, measured in both the time and frequency domain, during a quiet, resting baseline and in response to 5-min mental arithmetic and reaction time tasks, in 20 normal subjects measured in three testing sessions during a 9-month period. Stability, assessed by the intraclass correlation coefficient (ICC), was excellent for resting baseline measures of HR and HPV, with ICCs of 0.68-0.86. However, HR and HPV reactivity to either arithmetic or reaction time tasks generally was less stable, with ICCs of 0.17-0.73, in contrast to results of previous studies demonstrating long-term stability of HR responses to psychological challenge. Stability of aggregated reactivity scores was only slightly improved. Whether for individual tasks or aggregated measures, reactivity of total and low-frequency measures of HPV was moderately stable but stability of high-frequency HPV reactivity was poor.

Brief interval heart period variability by different methods of analysis correlates highly with 24 h analyses in normals

Heart period variability (HPV) measured from 24 h ECG recordings predicts mortality following myocardial infarction and may be a measure of cardiovascular health in the general population. Since epidemiologic evaluation of healthy people will require alternatives less intensive than 24 h recording, we investigated the relationship between HPV derived from 24 h and 5 min recordings, using two approaches for obtaining RR intervals. Template-matching (TM) algorithms were applied to 24 h ECG recordings from 41 normal subjects (mean age 35.7 +/- 13 years). Five min of ECG data during this 24 h period also were collected by an on-line microcomputer-based system for peak detection (PD) analysis. Intraclass correlations comparing the TM and PD approaches on the 5 min period were .80 or greater for all measures of HPV. Pearson correlation coefficients between the 5 min (TM) estimates and 24 h data and 5 min (PD) estimates and 24 h data exceeded .60 and .55, respectively, for all but one variable, with all p values < .05. Thus, in healthy adults, TM and PD approaches to HPV estimation from short segments of ECG data are highly consistent and the correlations between HPV obtained from brief intervals and 24 h measures were substantial, suggesting that assessment of HPV as a screening measure of cardiac autonomic control in healthy adults may be feasible.

Cardiac denervation and cardiovascular reactivity to psychological stress

OBJECTIVE

This study investigated the mechanisms responsible for increases in heart rate and blood pressure during psychological stress, which are incompletely understood. Since cardiac transplant patients have denervated hearts, they provide a unique model for isolating central versus peripheral influences on the cardiovascular response to stress.

METHODS

The authors compared the responses to two laboratory stressors of 20 ambulatory heart transplant recipients and two groups of normal subjects, one whose ages were matched to the ages of the transplant patients (mean = 46 years) and one whose ages were matched to the ages of the heart donors (mean = 27 years). The three groups of subjects performed mental arithmetic and reaction time tasks.

RESULTS

Heart rate increase during the mental arithmetic task was significantly attenuated in the transplant recipients. During stress, stroke volume increased in the transplant recipients but decreased in both groups of comparison subjects. The difference in age between the heart recipients and donors did not account for the difference in reactivity between the heart transplant patients and the normal subjects.

CONCLUSIONS

Direct neural stimulation of the heart is more important than peripherally circulating factors in producing tachycardia during psychological stress. Cardiac but not vascular responses to psychological stress are altered by cardiac denervation.

Effect of mental stress throughout the day on cardiac autonomic control

Although many laboratory studies have demonstrated changes in cardiac autonomic control during psychological stress, few have attempted to demonstrate this effect in ambulatory subjects. To address this issue, 24-h electrocardiographic recordings of 33 healthy subjects were analyzed for RR interval and heart period variability (HPV) responses associated with periodic diary entries measuring physical position, negative effect, and time of day. A total of 362 diary entries were made during the 24-h sessions, each in response to a device which signaled on an average of once per hour. HPV was analyzed in the frequency domain, yielding estimates of spectral power in low (LF) and high (HF) frequency bands, as well as the LF/HF ratio. Because of the high correlations of the measures of negative affect (alpha = 0.91), they were combined to create a single index of stress. Multivariate analysis was used to assess the effect of individual subject differences, physical position, and stress on RR interval and HPV. Results revealed significant effects of individual differences, stress, and physical position on RR interval, with increases in stress associated with decreases in RR interval as expected. HF power was significantly lower and the LF/HF ratio significantly higher in the standing compared with the sitting position. Psychological stress was significantly associated with an increase in the LF/HF ratio, suggesting increases in the relative predominance of sympathetic nervous system activity during stressful periods of the day. Overall, these findings suggest that in ambulatory normal subjects, cardiac autonomic control varies throughout the day as a function of self-reported stress.

Effects of desipramine on autonomic control of the heart

OBJECTIVE

To assess the effects of desipramine (DMI) on autonomic control of the heart.

METHODS

Blood pressure, RR interval (the time between successive heart beats), and RR interval variability, a noninvasive measure of autonomic control of the heart, were assessed in 13 subjects younger than 30 years old.

RESULTS

DMI treatment was associated with an increase in blood pressure, a decrease in RR interval, and a decline in low and high frequency RR interval variability.

CONCLUSIONS

These preliminary data suggest that, in young people, DMI treatment produces a substantial decrease in parasympathetic input to the heart and an increase in the ratio of sympathetic to parasympathetic input, changes that in certain circumstances have been associated with an increased risk of arrhythmia. In exploring the cardiac effects of the tricyclic antidepressants (TCAs) in young people, the impact of TCAs on autonomic input to the heart should be examined.

Effect of innervation on heart rate response to mental stress

Heart transplant recipients provide a useful model for study of the autonomic control of the cardiovascular response to mental stress. Utilizing the innervated native atrial tissue of heart transplant recipients as an internal control exposed to the same circulatory milieu as the denervated graft heart was exposed to, the effect of innervation on the heart rate response to a mentally stressful arithmetic task was examined in eight subjects. Compared with the graft, the innervated atrial tissue manifested a larger heart rate increase during the task, larger heart rate decrease after the task, and more rapid rate of change in heart rate during the task and recovery periods. Thus, cardiac denervation results in a chronotropic response to mental arithmetic-induced stress that is blunted and more gradual than that of the innervated heart but not completely eliminated. The cardiac chronotropic response to mental arithmetic stress is dependent on both humoral factors and, predominantly, its direct autonomic innervation.

Pharmacologic responses and spectral analyses of spontaneous fluctuations in heart rate and blood pressure in SHR rats

The aim of this experiment was to characterize patterns of autonomic control in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats by measuring effects of pharmacologic blockers and using power spectral analysis of heart rate variability (HRV) and blood pressure variability (BPV). Resting HRs and BPs were recorded during a 20-min baseline period and over two 20-min periods of sequential autonomic blockade. On one day, animals received atropine followed by atenolol and on the following day, the drug order was reversed. Power spectrum analyses were performed on 30-s blocks of data throughout each of the three 20-min treatment periods (baseline, single blocker, combined blockade) and HRV and BPV were computed over low and high frequency bands. Increases in HR after atropine were significantly (approx. 40%) smaller in SHR rats than in WKYs. This held true even when animals were pretreated with atenolol. In contrast, decreases in HR following atenolol were similar in the two strains. These results indicate that SHRs have reduced vagal tone, but similar cardiac sympathetic tone compared to WKY rats. Virtually all HRV, over both low and high frequency bands, and in both strains, was inhibited by atropine. SHRs had significantly less high frequency HRV which is consistent with the conclusion that they have reduced cardiac vagal activity when compared with WKYs. BPV was not affected by atropine or atenolol but was inhibited by an alpha-receptor (phentolamine). BPV within both the low and high frequency bands was significantly greater in SHRs, suggesting that sympathetic tone to the vasculature is greater in SHR rats.

Components of heart rate reactivity during mental arithmetic with and without speaking

Reactivity to psychological stressors has been hypothesized to be related to the development of cardiovascular disease. Because mental arithmetic (MA) has been shown to produce significant increases in heart rate and blood pressure, it is one of the most commonly utilized laboratory psychological stressors. However, the use of MA to assess hemodynamic reactivity raises two issues: 1) increases in heart rate can be produced by vagal withdrawal, sympathetic activation, or a combination of the two, and these mechanisms may differ in their pathogenic implications; and 2) in most MA studies, subjects are instructed to perform the task aloud, thus raising the possibility that speaking may interfere with respiratory patterns which in turn can influence hemodynamic outcomes. To address these two issues, we studied heart rate responses of 10 subjects to 2 different versions of MA and a control condition in which vocalization of answers was manipulated. Heart rate (HR), heart rate variability (HRV) in the low frequency (LB) and respiratory frequency (RSA) bands, and respiratory rate were measured. Results indicate that, although the two task conditions produced similar heart rate increases, RSA decreased only in the nonspeaking condition. Overall, the findings suggest that HR changes during MA are attributable to vagal withdrawal but that vocalization of answers during the task interferes with analysis of HRV, thus obscuring the mechanisms responsible for these changes.

Biobehavioral factors in Cardiac Arrhythmia Pilot Study (CAPS). Review and examination

The behavioral studies component of the multicenter Cardiac Arrhythmia Pilot Study (CAPS) was designed to examine the relation of biobehavioral factors and frequency of ventricular premature complexes (VPCs), efficacy of antiarrhythmic therapy, and disease end points in a study population that had experienced recent myocardial infarction and significant ventricular ectopy. Biobehavioral factors included both psychosocial (depression, anxiety, social support, type A behavior, mood, defensiveness, and anger expressiveness) and psychophysiological (heart rate and blood pressure reactivity to a videogame stressor) variables. Data were collected at baseline and at 3-, 6-, 9-, and 12-month follow-ups. Of the 502 patients enrolled in CAPS, 353 participated in the behavioral studies component. At baseline, assessments of psychosocial variables revealed the CAPS study population to be generally similar to other heart disease populations, and no relation between these variables and psychophysiological reactivity or arrhythmias was found. At follow-up among patients assigned to the placebo condition, biobehavioral variables were not related to levels of VPCs or VPC suppression. Cox regression analyses revealed that type B behavior, depression, and reduced heart rate reactivity were associated with increased clinical events, even after controlling for baseline left ventricular ejection fraction, myocardial infarction before the qualifying event, use of beta-blockers, use of digitalis, Q wave of qualifying myocardial infarction, and presence of unsustained ventricular tachycardia on baseline electrocardiogram. It is hypothesized that the relation among reduced heart rate reactivity, depression, and clinical events is mediated by diminished cardiac vagal tone.

Cessation and relapse in a year-long workplace quit-smoking contest

In an attempt to increase the impact of smoking cessation activities, some recent studies have examined the use of contests and competitions. The study reported here evaluates a year-long multiple-lottery quit-smoking contest at Volvo Flygmotor, the Volvo aircraft engine manufacturing company in Trollhattan, Sweden. Lotteries were held at 1, 6, and 12 months after the contest began. By quitting for at least 1 month, enrollees were eligible to win cash prizes. Maintaining nonsmoking status from a previous lottery automatically qualified enrollees for the next one. Smoking status was established by self-report, expired carbon monoxide, and saliva cotinine. Seventy-three employees, representing approximately 10% of the company's smokers, entered the contest during the initial 2-week enrollment period. Point prevalence 1-month and 6-month cessation rates were 64.4 and 49.3%, respectively. Continuous abstinence 6-month and 1-year rates were 45.2 and 32.8% respectively. Psychological, home, work and smoking history variables generally were not related to cessation or relapse.