Neural and psychologic mechanisms and the problem of sudden cardiac death

Physical activity, cardiorespiratory fitness, and cardiovascular health: A clinical practice statement of the ASPC Part I: Bioenergetics, contemporary physical activity recommendations, benefits, risks, extreme exercise regimens, potential maladaptations

Regular moderate-to-vigorous physical activity (PA) and increased levels of cardiorespiratory fitness (CRF) or aerobic capacity are widely promoted as cardioprotective measures in the primary and secondary prevention of atherosclerotic cardiovascular (CV) disease (CVD). Nevertheless, physical inactivity and sedentary behaviors remain a worldwide concern. The continuing coronavirus (COVID-19) pandemic has been especially devastating to patients with known or occult CVD since sitting time and recreational PA have been reported to increase and decrease by 28% and 33%, respectively. Herein, in this first of a 2-part series, we discuss foundational factors in exercise programming, with specific reference to energy metabolism, contemporary PA recommendations, the dose-response relationship of exercise as medicine, the benefits of regular exercise training, including the exercise preconditioning cardioprotective phenotype, as well as the CV risks of PA. Finally, we discuss the 'extreme exercise hypothesis,' specifically the potential maladaptations resulting from high-volume, high-intensity training programs, including accelerated coronary artery calcification and incident atrial fibrillation. The latter is commonly depicted by a reverse J-shaped or U-shaped curve. On the other hand, longevity data argue against this relationship, as elite endurance athletes live 3-6 years longer than the general population.

High level physical activity in cardiac rehabilitation: Implications for exercise training and leisure-time pursuits

IMPORTANCE

Regular moderate-to-vigorous physical activity and increased levels of cardiorespiratory fitness (CRF) are widely promoted as cardioprotective measures in secondary prevention interventions.

OBSERVATIONS

A low level of CRF increases the risk of cardiovascular disease (CVD) to a greater extent than merely being physically inactive. An exercise capacity <5 metabolic equivalents (METs), generally corresponding to the bottom 20% of the fitness continuum, indicates a higher mortality group. Accordingly, a key objective in early cardiac rehabilitation (CR) is to increase the intensity of training to >3 METs, to empower patients to vacate this "high risk" group. Moreover, a "good" exercise capacity, expressed as peak METs, identifies individuals with a favorable long-term prognosis, regardless of the underlying extent of coronary disease. On the other hand, vigorous-to-high intensity physical activity, particularly when unaccustomed, and some competitive sports are associated with a greater incidence of acute cardiovascular events. Marathon and triathlon training/competition also have limited applicability and value in CR, are associated with acute cardiac events each year, and do not necessarily provide immunity to the development of or the progression of CVD. Furthermore, extreme endurance exercise regimens are associated with an increased incidence of atrial fibrillation and accelerated coronary artery calcification.

CONCLUSIONS AND RELEVANCE

High-intensity training offers a time-saving alternative to moderate intensity continuous training, as well as other potential advantages. Additional long-term studies assessing safety, adherence, and morbidity and mortality are required before high-intensity CR training can be more widely recommended, especially in previously sedentary patients with known or suspected CVD exercising in non-medically supervised settings.

Chronic Stress, Exercise and Cardiovascular Disease: Placing the Benefits and Risks of Physical Activity into Perspective

Chronic stress, which has been exacerbated worldwide by the lingering COVID pandemic, has been strongly linked to cardiovascular disease (CVD). In addition, autonomic dysregulation via sustained sympathetic activity has been shown to increase the risk of arrhythmias, platelet aggregation, acute coronary syndromes and heart failure. Fortunately, effective coping strategies have been shown to attenuate the magnitude of hyperarousal associated with the stress response, including moderate-to-vigorous lifestyle activity and/or structured exercise. A good-to-excellent level of cardiorespiratory fitness also appears to be highly cardioprotective. These beneficial effects have been substantiated by numerous studies that have evaluated the levels of stress reactivity and stress recovery in physically active individuals versus matched sedentary controls, as well as before and after exercise interventions. On the other hand, unaccustomed strenuous exercise in habitually sedentary persons with underlying CVD is associated with a disproportionate incidence of acute cardiac events. Moreover, extreme exercise regimens appear to increase coronary calcification and the likelihood of developing atrial fibrillation. This review summarizes these relations and more, with specific reference to placing the benefits and risks of physical activity into perspective.

Sympathetic and Vagal Responses Elicited by Acute Stress in Rats

Introduction

Acute emotional stress triggers autonomic responses that affect sympathovagal balance. However, the temporal pattern of changes in each autonomic arm during stress and recovery remains unclear. Therefore, we analyzed separately sympathetic and vagal activity, elicited by acute unpredictable stress in a rat model.

Methods

Continuous electrocardiographic recording was performed during (32 minutes) and after (two hours) successive use of restraint and air-jet stress in 10 rats, whereas five rats served as controls. Sympathetic and vagal indices were calculated non-invasively after heart rate variability analysis. Voluntary motion was quantified during recovery, as an index of continuing anxiety.

Results

The sympathetic nervous system index increased during stress and remained elevated during the initial stage of recovery. The parasympathetic nervous system index decreased immediately after the onset of stress and remained low throughout the observational period. During recovery, voluntary activity was more pronounced in the stress group than in the controls.

Conclusion

Successive restraint and air-jet stress in rats increased sympathetic activity and decreased vagal activity. These changes displayed only partial recovery post-stress and were accompanied by enhanced voluntary motion. Our findings may be important in the evaluation of the cardiac electrophysiologic implications of autonomic changes elicited by acute emotional stress.

Exercise-Related Acute Cardiovascular Events and Potential Deleterious Adaptations Following Long-Term Exercise Training: Placing the Risks Into Perspective-An Update: A Scientific Statement From the American Heart Association

Epidemiological and biological plausibility studies support a cause-and-effect relationship between increased levels of physical activity or cardiorespiratory fitness and reduced coronary heart disease events. These data, plus the well-documented anti-aging effects of exercise, have likely contributed to the escalating numbers of adults who have embraced the notion that "more exercise is better." As a result, worldwide participation in endurance training, competitive long distance endurance events, and high-intensity interval training has increased markedly since the previous American Heart Association statement on exercise risk. On the other hand, vigorous physical activity, particularly when performed by unfit individuals, can acutely increase the risk of sudden cardiac death and acute myocardial infarction in susceptible people. Recent studies have also shown that large exercise volumes and vigorous intensities are both associated with potential cardiac maladaptations, including accelerated coronary artery calcification, exercise-induced cardiac biomarker release, myocardial fibrosis, and atrial fibrillation. The relationship between these maladaptive responses and physical activity often forms a U- or reverse J-shaped dose-response curve. This scientific statement discusses the cardiovascular and health implications for moderate to vigorous physical activity, as well as high-volume, high-intensity exercise regimens, based on current understanding of the associated risks and benefits. The goal is to provide healthcare professionals with updated information to advise patients on appropriate preparticipation screening and the benefits and risks of physical activity or physical exertion in varied environments and during competitive events.

Association of positive well-being with reduced cardiac repolarization abnormalities in the First National Health and Nutrition Examination Survey

BACKGROUND

The mechanisms by which psychological factors may influence possibly arrhythmia risk are not known. We hypothesized that psychological wellness, measured by the General Well-Being Schedule (GBWS), is associated with less repolarization heterogeneity as measured by T-axis. We also explored whether T-axis was a mediator in the relationship of GWBS with adverse cardiac outcomes.

METHODS

We studied 5533 adults aged 25-74 years without a history of CVD from NHANES I (National Health and Nutrition Examination Survey) (1971-75). Frontal T-axis was obtained through 12-lead ECG and characterized as normal (15° to 75°), borderline (-15° to 15° or 75° to 105°) or abnormal (>105° or <-15°).

RESULTS

The mean ± SD age was 43.1 ± 11.5 years and 55% were women. A 1-SD increase in GWBS score associated with a 23% reduced odds of abnormal T-axis (p < 0.001) and 11% lower hazard of composite CHD hospitalization and death (p = 0.02). When adjusting for sociodemographic factors, health behaviors, and CHD risk factors, the association was minimally changed and remained statistically significant. Additional adjustment for T-axis did not change the relationship with outcomes.

CONCLUSION

General well-being is independently associated with less abnormal frontal T-axis and CHD events in otherwise healthy individuals.

The association between hope and mortality in homebound elders

OBJECTIVE

Despite high rates of mortality and depression, there is limited knowledge of how depressive symptoms, especially feeling of hopefulness, affect mortality in the homebound elderly.

METHODS

We conducted a secondary analysis of data from a community sample of 1034 adults, age 60 years and older. The Center for Epidemiologic Studies Depression Scale was used to evaluate the mood symptoms and feeling of hopefulness at baseline. The death data were collected within an 8-year follow-up period. Analysis of variance and Chi-square were used to compare the clinical conditions among the groups of individuals who feel hopeful always, sometimes, and rarely. Logistic regression was used to explore the association between the hopefulness about the future and mortality as an outcome.

RESULTS

In the 8-year follow-up period, frequency of feeling hopeful, but not other individual depressive symptoms, was associated with mortality rate. The mortality rate among those who always, sometimes, and rarely felt hopeful were 21.6%, 26.4%, and 35.7%, respectively (P = 0.002). Logistic regression also confirmed that individuals who rarely feel hopeful had higher odds of decease within the 8-year follow-up period than those who always felt hopeful (OR = 1.74, CI = 1.14-2.65) after adjusting for age and medical conditions.

CONCLUSIONS

Baseline hopefulness predicts mortality outcome among the homebound elderly in the community. Identifying individuals who are depressed with hopelessness in the elderly and providing early intervention may improve the mortality rate. Copyright © 2017 John Wiley & Sons, Ltd.

Diabetic autonomic neuropathy

Diabetes mellitus is the commonest cause of an autonomic neuropathy in the developed world. Diabetic autonomic neuropathy causes a constellation of symptoms and signs affecting cardiovascular, urogenital, gastrointestinal, pupillomotor, thermoregulatory, and sudomotor systems. Several discrete syndromes associated with diabetes cause autonomic dysfunction. The most prevalent of these are: generalized diabetic autonomic neuropathy, autonomic neuropathy associated with the prediabetic state, treatment-induced painful and autonomic neuropathy, and transient hypoglycemia-associated autonomic neuropathy. These autonomic manifestations of diabetes are responsible for the most troublesome and disabling features of diabetic peripheral neuropathy and result in a significant proportion of the mortality and morbidity associated with the disease.

Acute Stress Decreases but Chronic Stress Increases Myocardial Sensitivity to Ischemic Injury in Rodents

Cardiovascular disease (CVD) is the largest cause of mortality worldwide, and stress is a significant contributor to the development of CVD. The relationship between acute and chronic stress and CVD is well evidenced. Acute stress can lead to arrhythmias and ischemic injury. However, recent evidence in rodent models suggests that acute stress can decrease sensitivity to myocardial ischemia-reperfusion injury (IRI). Conversely, chronic stress is arrhythmogenic and increases sensitivity to myocardial IRI. Few studies have examined the impact of validated animal models of stress-related psychological disorders on the ischemic heart. This review examines the work that has been completed using rat models to study the effects of stress on myocardial sensitivity to ischemic injury. Utilization of animal models of stress-related psychological disorders is critical in the prevention and treatment of cardiovascular disorders in patients experiencing stress-related psychiatric conditions.

Antagonism of endogenous nociceptin/orphanin FQ inhibits infarction-associated ventricular arrhythmias via PKC-dependent mechanism in rats

BACKGROUND AND PURPOSE

Evidence indicates nociceptin/orphanin FQ (N/OFQ) may participate in the pathology of cardiac arrhythmias associated with myocardial infarction. But the role of N/OFQ in the arrhythmogenesis in acute myocardial infarction is unclear. The aim of this study was to investigate the effects of endogenous N/OFQ on infarction-associated arrhythmias.

EXPERIMENTAL APPROACH

The expression of N/OFQ, PKC activity and ventricular arrhythmias in presence and absence of UFP-101, a specific antagonist of N/OFQ receptor, were examined following permanent coronary artery occlusion in anaesthetized rats. The effect of N/OFQ on action potential duration was examined in isolated rat cardiomyocytes.

KEY RESULTS

It was observed that N/OFQ was increased by 41% in the myocardium after coronary artery occlusion (P < 0.01 vs. control). Pretreatment with UFP-101 (10(-7)  mol·kg(-1) , i.v.) reduced the incidence of ventricular ectopic beats by 70% and ventricular tachycardia by 51% respectively (all P < 0.05 vs. control). Meanwhile, PKC activity was elevated in the rats treated with UFP-101 (by 35%, P < 0.05 vs. control). A selective PKC inhibitor, calphostin C, completely abolished the anti-arrhythmic effects of UFP-101 (P < 0.01). N/OFQ (at 10(-11) , 10(-9) and 1 × 10(-7)  mol·L(-1) ) shortened the action potential duration by 3% (P > 0.05), 10% (P < 0.05) and 22% (P < 0.01), respectively, via N/OFQ receptor.

CONCLUSIONS AND IMPLICATIONS

Antagonism of endogenous N/OFQ produces anti-arrhythmic effects on ventricular arrhythmias in acute myocardial infarction, possibly via modulating PKC activity and action potential of myocytes.

Putting the benefits and risks of aerobic exercise in perspective

Although considerable epidemiologic and clinical evidence suggests that structured exercise, increased lifestyle activity, or both are cardioprotective, the absolute and relative risk of cardiovascular and musculoskeletal complications appear to increase transiently during vigorous physical activity. The estimated relative risk of exercise-related cardiac events ranges from 2.1 to 56 and is highest among habitually sedentary individuals with underlying cardiovascular disease who were performing unaccustomed vigorous physical exertion. Moreover, an estimated 7 million Americans receive medical attention for sports and recreation-related injuries each year. These risks, and their modulators, should be considered when endorsing strenuous leisure time or exercise interventions. If the current mantra "exercise is medicine" is embraced, underdosing and overdosing are possible. Thus, exercise may have a typical dose-response curve with a plateau in benefit or even adverse effects, in some individuals, at more extreme levels.

Engel's biopsychosocial model is still relevant today

In 1977, Engel published the seminal paper, "The Need for a New Medical Model: A Challenge for Biomedicine" [Science 196 (1977) 129-136]. He featured a biopsychosocial (BPS) model based on systems theory and on the hierarchical organization of organisms. In this essay, the model is extended by the introduction of semiotics and constructivism. Semiotics provides the language which allows to describe the relationships between the individual and his environment. Constructivism explains how an organism perceives his environment. The impact of the BPS model on research, medical education, and application in the practice of medicine is discussed.

Relation between ventricular arrhythmias and psychological profile

The association between psychological characteristics and ventricular arrhythmias was investigated in 150 men (50 with manifest IHD, 50 with risk indicators of IHD and 50 healthy men). Arrhythmias were recorded with 24-hour Holter monitoring. Psychological characteristics were assessed by the Emotions Profile Index and the Structured Interview for pattern A behaviour. A depressive emotional state was associated with prognostically severe ventricular arrhythmia in healthy men, but not in men with overt IHD or risk indicators of IHD. When clinical characteristics and age were taken into account, depressiveness was-among healthy men-the second most important factor after high age. The results suggest that-in absence of IHD or other cardiovascular disease-a depressive emotional state may participate in the formation of ventricular arrhythmia.

Experimental studies of psychophysiological factors in sudden cardiac death

Earlier research in the field of sudden cardiac death is reviewed. Such studies have largely oriented towards the provocation of myocardial injury and asystole in normal animals. However, such investigations constitute an inadequate model to describe the clinical appearance of sudden death, where underlying coronary disease is often present and the precipitating event is usually ventricular fibrillation rather than asystole. This report describes a series of studies designed to investigate the processes underlying cardiac vulnerability and the influence upon it of various psychological stresses. It is concluded that the primary mediator of ventricular vulnerability is the sympathetic nervous system. The efferent vagus appears to exert some protective influence against arrhythmias due to adrenergic stimulation. An appropriate clinical strategy for the treatment of malignant arrhythmias would therefore involve attempts to decrease cardiac sympathetic drive whilst at the same time enhancing vagal tone. Treatments are described which aim to bring this situation about by the use of clonidine, morphine sulphate, l-tryptophan and tyrosine. The use of neurochemical agents in this context appears promising.

In vivo PET imaging of cardiac presynaptic sympathoneuronal mechanisms in the rat

The sympathetic nervous system of the heart plays a key role in the pathophysiology of various cardiac diseases. Small-animal models are valuable for obtaining further insight into mechanisms of cardiac disease and therapy. To determine the translational potential of cardiac neuronal imaging from rodents to humans, we characterized the rat sympathetic nervous system using 3 radiotracers that reflect different subcellular mechanisms: (11)C-meta-hydroxyephedrine (HED), a tracer of neuronal transport showing stable uptake and no washout in healthy humans; (11)C-phenylephrine (PHEN), a tracer of vesicular leakage and intraneuronal metabolic degradation with initial uptake and subsequent washout in humans; and (11)C-epinephrine (EPI), a tracer of vesicular storage with stable uptake and no washout in humans.

METHODS

We used a small-animal PET system to study healthy male Wistar rats at baseline, after desipramine (DMI) pretreatment (DMI block), and with DMI injection 15 min after tracer delivery (DMI chase). The rats were kept under general isoflurane anesthesia while dynamic emission scans of the heart were recorded for 60 min after radiotracer injection. A myocardial retention index was determined by normalizing uptake at 40 min to the integral under the arterial input curve. Washout rates were determined by monoexponential fitting of myocardial time-activity curves.

RESULTS

At baseline, HED showed high myocardial uptake and sustained retention, EPI showed moderate uptake and significant biphasic washout, and PHEN showed moderate uptake and monoexponential washout. The average (+/- SD) left ventricular retention index for HED, PHEN, and EPI was 7.38% +/- 0.82%/min, 3.43% +/- 0.45%/min, and 4.24% +/- 0.59%/min, respectively; the washout rate for HED, PHEN, and EPI was 0.13% +/- 0.23%/min, 1.13% +/- 0.35%/min, and 0.50% +/- 0.24%/min, respectively. The DMI chase resulted in increased washout only for HED. DMI block decreased myocardial uptake of all tracers by less than 90%.

CONCLUSION

Kinetic profiles of HED in the rat myocardium were similar to those of HED in humans, suggesting comparable neuronal transport density. Unlike in humans, however, significant washout of EPI and faster washout of PHEN were encountered, consistent with high intraneuronal metabolic activity, high catecholamine turnover, and reduced vesicular storage. This evidence of increased neuronal activity in rodents has implications for translational studies of cardiac neuronal biology in humans.

Stroke and cardiac arrhythmias

Stroke is frequently followed by electrocardiographic (ECG) changes. The aim of the present study was to evaluate the global incidence of these changes after ischemic or hemorrhagic strokes, but it focused on cardiac arrhythmias. In ischemic strokes, these were correlated with the side of the lesion(s). The study was retrospective, and 450 patients (out of 971 examined) were entered in the study based on the following inclusion criteria: (1) "completed" stroke (352 ischemic and 98 hemorrhagic), (2) ECG on admission, and (3) at least 1 previous ECG. We also examined 71 patients with carotid or vertebro-basilar transient ischemic attacks (TIA). As controls, 71 patients suffering from nonvascular neurologic diseases were examined. The results were as follows: In stroke patients, new-onset ECG abnormalities were present in 75% of cases, and cardiac arrhythmias accounted for 28.7%. Cardiac arrhythmias were observed in 21.9% of ischemic strokes (26.8% of patients with right hemispheric lesion and 14.3% of those with left hemispheric lesion) and in 20.4% of hemorrhagic strokes, with the highest incidence in subarachnoid hemorrhage (37.5%). The mechanisms of genesis of cardiac arrhythmias occurring after stroke are still not well understood. Some evidence supports the hypothesis of a "cardiac cortical rhythm control site," probably lying within the middle cerebral artery territory. Vascular damage to this area could be followed by cardiac arrhythmias related to a disinhibition of the right insular cortex with resulting increased sympathetic tone. Our data seem to indicate that ischemic involvement of the right hemisphere induces a higher risk for cardiac arrhythmia occurrence than that of the left hemisphere.

Prehospital analgesia with acupressure at the Baihui and Hegu points in patients with radial fractures: a prospective, randomized, double-blind trial

BACKGROUND

Pain during transportation is a common phenomenon in emergency medicine. As acupressure has been deemed effective for pain management by the National Institutes of Health, we conducted a study to evaluate its effectiveness in prehospital patients with isolated distal radial fracture.

METHODS

This was a prospective, randomized, double-blind study. Thirty-two patients were enrolled. Acupressure was performed either at "true" points or at "sham" points. Vital signs and pain and anxiety scores were recorded before and after the acupressure treatment. Normally distributed values were compared using the Student t test.

RESULTS

Pretreatment scores for pain and anxiety were similar in the 2 groups (47.6 +/- 8.9 vs 51.2 +/- 8.7 visual analog scale [VAS] score for pain, 52.4 +/- 6.0 vs 47.5 +/- 9.3 VAS score for anxiety). At the hospital, patients in the true-points group had significantly lower pain (36.6 +/- 11.0 vs 56.0 +/- 13.3 VAS score, P < .001) and anxiety scores (34.9 +/- 22.2 vs 53.4 +/- 19.7 VAS score, P = .022).

CONCLUSION

Acupressure in the prehospital setting effectively reduces pain and anxiety in patients with distal radial trauma.

Electrocardiographic responses to deer hunting activities in men with and without coronary artery disease

To evaluate the cardiac demands of hunting deer, continuous ambulatory electrocardiograms were obtained in men with and without coronary artery disease (CAD) and compared with their responses to maximal treadmill testing. A volunteer sample of 25 middle-aged men (mean +/- SD 55 +/- 7 years of age), 17 of whom had known CAD, completed the study. Peak heart rate (HR) during 7 different deer hunting activities was expressed as the mean percentage of the maximal HR (HRmax) attained during treadmill testing. Periods of sustained sinus tachycardia were identified. Arrhythmias and ST-segment depression during deer hunting that were not apparent during treadmill testing were documented. Overall, 22 of 25 subjects demonstrated HR responses >85% HRmax for 1 to 65 minutes. Ten subjects exceeded the HRmax achieved during treadmill testing for 1 to 5 minutes. The relative HR response during ambulatory activity in the field was inversely related to cardiorespiratory fitness, expressed as METs (r = -0.59; p = 0.0020). Three subjects had ischemic electrocardiograms during deer hunting, but not during treadmill testing. Complex arrhythmias in the field not detected by treadmill testing included ventricular bi-trigeminy, ventricular couplets, and 8 runs of ventricular tachycardia (3 to 28 beats) in 3 subjects with documented CAD. In conclusion, deer hunting can evoke sustained HRs, ischemic ST-segment depression, and threatening ventricular arrhythmias in excess of those documented during maximal treadmill testing. The strenuous nature of deer hunting coupled with presumed hyperadrenergia and superimposed environmental stresses may contribute to the excessive cardiac demands associated with this activity.

Anxiety Worsens Prognosis in Patients With Coronary Artery Disease

OBJECTIVES

This study examined the effect of anxiety on mortality and nonfatal myocardial infarction (MI) in patients with coronary artery disease (CAD).

BACKGROUND

Inconsistent data exist regarding the impact of anxiety on the prognosis of patients with CAD.

METHODS

The authors conducted a prospective cohort study at an outpatient cardiology clinic of 516 patients with CAD (mean age 68 years at entry, 82% male) by administering the Kellner Symptom Questionnaire annually. The primary outcome was the composite of nonfatal MI or all-cause mortality.

RESULTS

During an average follow-up of 3.4 years, we documented 44 nonfatal MIs and 19 deaths. A high cumulative anxiety score was associated with an increased risk of nonfatal MI or death. Comparing the highest to lowest tertile of anxiety score, the age-adjusted hazard ratio was 1.97 (95% confidence interval 1.03 to 3.78, p = 0.04). In a multivariate Cox model after adjusting for age, gender, education, marital status, smoking, hypertension, diabetes mellitus, previous MI, body mass index, and total cholesterol, each unit increase in the cumulative mean anxiety score was associated with increased risk of nonfatal MI or total mortality; the hazard ratio was 1.06 (95% confidence interval 1.01 to 1.12, p = 0.02).

CONCLUSIONS

A high level of anxiety maintained after CAD diagnosis constitutes a strong risk of MI or death among patients with CAD.

Demonstration of circadian rhythm in heart rate turbulence using novel application of correlator functions

BACKGROUND

Demonstration of a circadian rhythm in two parameters of heart rate turbulence--turbulence onset (TO) and turbulence slope (TS)--has been difficult.

OBJECTIVE

The aim of this study was to devise a new method for detecting circadian rhythm in noisy data and to apply it to selected Holter recordings from two postmyocardial infarction databases: Cardiac Arrhythmia Suppression Trial (CAST, n = 684) and Innovative Stratification of Arrhythmic Risk (ISAR, n = 327).

METHODS

For each patient, TS and TO were calculated for each hour with >4 ventricular premature contractions (VPCs). An autocorrelation function Corr(Deltat) = <TS(t) TS(t + Deltat)> then was calculated and averaged over all patients. Positive Corr(Deltat) indicates that TS at a given hour and Deltat hours later are similar. TO was treated likewise. Simulations and mathematical analysis showed that a circadian rhythm required Corr(Deltat) to have a U-shape consisting of positive values near Deltat = 0 and 23 and negative values for intermediate Deltat. Significant deviation of Corr(Deltat) from the correlator function of pure noise was evaluated as a Chi-square value.

RESULTS

Circadian patterns were not apparent in hourly averages of TS and TO plotted against clock time, which had large error bars. However, their correlator functions produced Chi-square values of approximately 10 in CAST (both P <.0001) and approximately 3 in ISAR (both P <.0001), indicating the presence of circadian rhythmicity.

CONCLUSION

Correlator functions may be a powerful tool for detecting the presence of circadian rhythms in noisy data, even with recordings limited to 24 hours.

TENS Relieves Acute Posttraumatic Hip Pain During Emergency Transport

BACKGROUND

In Central Europe, ambulances for patients suffering from pain caused by nonlife-threatening trauma, such as hip fractures are staffed by medical personnel (medics) without physicians. Thus, there is an urgent need for nonpharmacological interventions that can be applied during the transport by basic life-support (BLS) medical personnel.

METHODS

In all, 101 patients were screened for participation in this randomized placebo-controlled double-blind study, and randomly assigned to two groups (verum and sham transcutaneous electrical nerve stimulation [TENS]). First, medic A recorded all baseline parameters and measurements, then medic B performed TENS in absence of medic A. At the end of transportation, medic A performed data collection. Each patient was asked to grade his/her pain and anxiety level on visual analog scales (VAS, 0 to 100 mm).

RESULTS

From 101 screened patients fulfilling the entry criteria, 29 declined consent and 9 had to be excluded from the analysis because of their final diagnosis. Therefore, the data from 30 patients (group 1, verum TENS) as well as from 33 patients (group 2 [control], sham TENS) were analyzed. No significant differences in potentially influencing factors were found before treatment. Pain scores upon arrival at the hospital differed significantly between group 1 and group 2 (p < 0.01). In group 1, pain reduction was observed between departure from the site of emergency and arrival at the hospital (VAS: 89 +/- 9 to 59 +/- 6 mm), whereas pain scores remained nearly unchanged in group 2 (VAS: 86 +/- 12 to 79 +/- 11 mm).

CONCLUSION

Our findings show that TENS is a valuable and fast-acting pain treatment under the difficult circumstances of "out-of-hospital rescue". Because of its lack of side effects, it could also be a valuable tool in the hospital.

Power spectrum analysis and cardiovascular morbidity in anxiety disorders

Spectral analysis of heart rate variability (HRV) and related measures has been shown to be a reliable noninvasive technique enabling quantitative assessment of cardiovascular autonomic regulatory responses to autonomic regulatory mechanisms; it provides a dynamic probe of sympathetic and parasympathetic tone, reflecting the interactions between the two. Over 20 studies reported abnormalities of HRV in anxiety, and patients with heart disease and anxiety are at increased risk for morbidity and mortality. Psychiatric drugs partly correct abnormalities of HRV and, recently, autonomic drugs (beta-blockers) have been studied in anxiety disorders. The authors call for further studies, especially in patients with co-existing anxiety disorders and heart disease, incorporating assessment of HRV.

Depression and Anxiety in Heart Failure

BACKGROUND

Although common among patients with heart failure, depression and anxiety have been relatively neglected by researchers and practitioners. Both depression and anxiety have been implicated in contributing independently to the poor outcomes seen in patients with heart failure. Emphasis in the literature is on physical symptom recognition and management, in contrast to the patient's perspective of the effects of heart failure on his or her daily life.

METHODS AND RESULTS

This review summarizes and integrates research findings on anxiety and depression and translates these findings to clinical practice. Depression and anxiety are prevalent among patients with heart failure and require assessment and intervention. Short-term nonpharmacologic approaches, in conjunction with drug therapy, hold promise for successful management of patients who are depressed or anxious.

CONCLUSION

Carefully designed clinical trials that are tailored to individual needs, yet are embedded within a systemic framework, are needed to inform clinicians regarding optimal practices for the treatment of patients with heart failure who suffer from depression or anxiety.

Prognostic significance of ventricular arrhythmia modified by ability to adapt to stressful situations

BACKGROUND

Ventricular arrhythmia is a risk factor for myocardial infarction and mortality but many individuals with this abnormality live long and healthy lives. The aim of this study is to analyse the prognostic significance of frequent and complex ventricular arrhythmia in men who differed regarding ability to adapt to a stressful situation.

DESIGN

Prospective cohort study.

METHODS

The serial Color Word Test is a semi-experimental way to assess how individuals behave in a stressful encounter. This test was included in the prospective cohort study 'Men born in 1914' together with 24-h ambulatory electrocardiographic recordings at a baseline examination in 1982/83. Behaviour in the test was categorized as either adaptive or maladaptive. Behaviour in the test and occurrence of ventricular arrhythmia at baseline were analyzed in relation to incidence of myocardial infarction and mortality during approximately 14 years of follow-up.

RESULTS

Multivariate analyses showed that ventricular arrhythmia was not associated with the incidence of myocardial infarction or all-cause mortality in the presence of an adaptive behaviour. Ventricular arrhythmia together with a maladaptive behaviour was associated with the incidence of myocardial infarction [relative risk (RR) 2.43; 95% confidence interval (CI) 1.37 to 4.31] and with all-cause mortality (RR 1.56; 95% CI 1.01 to 2.41) during follow-up.

CONCLUSIONS

A maladaptive behaviour in a stressful encounter makes men with electrocardiographically detected ventricular arrhythmias more vulnerable and thereby exposed to an increased risk of a future myocardial infarction and overall mortality.

Increased susceptibility to ventricular arrhythmias in a rodent model of experimental depression

Depression is an important public health problem and is considered to be an independent risk factor for coronary artery disease. The pathophysiological mechanisms that link depression with adverse cardiovascular events (e.g., myocardial ischemia, myocardial infarction, and sudden death) are not well established. It is possible that an increased susceptibility to life-threatening cardiac arrhythmias in depressed patients influences the risk of morbidity and mortality in coronary artery disease. This idea was tested with the use of an experimental model of depression that was developed to induce anhedonia, the reduced responsiveness to pleasurable stimuli observed in human depressed patients. Rats exposed to 4 wk of chronic mild stress (e.g., paired housing, strobe light, and white noise) displayed anhedonia, which was operationally defined by the reduced intake of a palatable sucrose solution relative to an established baseline and to control animals. Furthermore, compared with control rats, the anhedonic rats showed increased basal heart rate and decreased heart rate variability. In response to an intravenously infused chemical challenge, aconitine, anhedonic rats exhibited an increased vulnerability to ventricular arrhythmias, as indicated by a reduced threshold for premature ventricular complexes, salvos, and ventricular tachycardia. These findings suggest that the presence of depressive symptoms is associated with a lower threshold for ventricular arrhythmias, which may contribute to the increased risk for adverse cardiovascular events in patients with depression.

Self-care Resources and Activity as Predictors of Quality of Life in Persons After Myocardial Infarction

An ex post facto correlational study was conducted to examine predictors of quality of life in persons 3 to 6 months after a myocardial infarction. Self-care resources, self-care knowledge (needs), activity level, and selected demographic variables were examined as predictor variables. A convenience sample of 86 subjects with a mean age of 61 years, was recruited for participation in this study. The study that explained 35% of the variance in quality of life included self-care resources available, activity level, and self-care needs. Modeling and Role Modeling Paradigm provided a useful explanation of how self-care resources and self-care knowledge can be applied to persons recovering from myocardial infarction.

Safety of antidepressant drugs in the patient with cardiac disease: a review of the literature

Patients with cardiac disease, specifically ischemic heart disease and heart failure, have a higher frequency of major depressive disorder than patients without cardiac disease. The pathophysiologic reason for this is not completely understood. Previous depression, other debilitating illnesses, and type A personality are risk factors for the development of depression in cardiac patients. Depression has been shown to lower the threshold for ventricular arrhythmias. Therefore, treatment of depression potentially may prolong life in these patients. Antidepressant options that have been evaluated include several of the tricyclic antidepressants, trazodone, bupropion, and several of the selective serotonin reuptake inhibitors. Individual antidepressant drugs vary in their pharmacologic activity and side-effect profiles. Although clinical data are limited, it is important to individualize therapy in order to minimize cardiac adverse effects. Clinicians are encouraged to evaluate patients with cardiac disease for major depressive disorder and to consider antidepressant drug therapy for these patients when appropriate.

Protective effects of centrally acting sympathomodulatory drugs on myocardial ischemia induced by sympathetic overactivity in rabbits

It is recognized that an imbalance of the autonomic nervous system is involved in the genesis of ventricular arrhythmia and sudden death during myocardial ischemia. In the present study we investigated the effects of clonidine and rilmenidine, two centrally acting sympathomodulatory drugs, on an experimental model of centrally induced sympathetic hyperactivity in pentobarbital-anesthetized New Zealand albino rabbits of either sex (2-3 kg, N = 89). We also compared the effects of clonidine and rilmenidine with those of propranolol, a beta-blocker, known to induce protective cardiovascular effects in patients with ischemic heart disease. Central sympathetic stimulation was achieved by intracerebroventricular injection of the excitatory amino acid L-glutamate (10 micro mol), associated with inhibition of nitric oxide synthesis with L-NAME (40 mg/kg, iv). Glutamate triggered ventricular arrhythmia and persistent ST-segment shifts in the ECG, indicating myocardial ischemia. The intracisternal administration of clonidine (1 microg/kg) and rilmenidine (30 microg/kg) or of a nonhypotensive dose of rilmenidine (3 microg/kg) decreased the incidence of myocardial ischemia (25, 14 and 25%, respectively, versus 60% in controls) and reduced the mortality rate from 40% to 0.0, 0.0 and 12%, respectively. The total number of ventricular premature beats per minute fell from 30 +/- 9 in the control group to 7 +/- 3, 6 +/- 3 and 2 +/- 2, respectively. Intravenous administration of clonidine (10 micro g/kg), rilmenidine (300 microg/kg) or propranolol (500 microg/kg) elicited similar protective effects. We conclude that clonidine and rilmenidine present cardioprotective effects of central origin, which can be reproduced by propranolol, a lipophilic beta-blocking agent.

Hemodynamic response patterns to acute behavioral stressors resemble those to cocaine

Hemodynamic responses to cocaine vary greatly between animals, and the variability is related to the incidence of cocaine-induced cardiomyopathies and hypertension. The variability in cardiac output and systemic vascular resistance responses to cocaine in individuals is correlated with the responses to acute startle (air jet). This experiment was designed to determine whether responses to cocaine and to air jet are related to those evoked by a conditioned stimulus (tone preceding foot shock) and to an unconditioned stimulus (cold water). We verified the relationship in hemodynamic response patterns between cocaine and cold stress using selective receptor antagonists. Rats were instrumented with a pulsed Doppler flow probe on the ascending aorta for determination of cardiac output and with an arterial cannula for recording arterial pressure and heart rate. After recovery, some rats were tested multiple times with four different stimuli: air jet (6 trials), 15-s tone preceding 1-s foot shock (12 trials), cold water exposure (1 cm deep for 1 min, 4-12 trials), and cocaine (5 mg/kg iv, 4-6 trials) while hemodynamic parameters were recorded. Each stimulus was capable of eliciting a pressor response that was associated with variable changes in cardiac output. The cardiac output response to cocaine was correlated with the initial responses to each stressor in individual rats. Responses evoked by cold stress were most similar to those elicited by cocaine. Furthermore, nicardipine (25 microg/kg iv) or atropine methylbromide (0.5 mg/kg iv) pretreatment prevented the cardiac output differences to acute cold stress, as noted after cocaine administration. On the other hand, propranolol (1 mg/kg iv) exacerbated both the decrease in cardiac output and the stress-induced increase in systemic vascular resistance as previously reported with cocaine. Therefore, the initial response to cold water exposure is a reliable method of evoking characteristic hemodynamic response patterns that, as seen with cocaine, may provide a suitable model for identifying the causes for predilection to stress-induced cardiovascular disease.

Cardiovascular effects of chronic ifenprodil in a model of central sympathetic stimulation

In the present study we investigated the effects of a long-term treatment (14 days) with ifenprodil on the excitatory haemodynamic responses induced by central pharmacological stimulation in anaesthetised rabbits. The intracerebroventricular injection of L-glutamate (3 mg/kg) induced important rises in dP/dtmax (32.9%), mean arterial pressure (42.6%) and in the myocardial oxygen consumption index: the triple product (84.2%). Ifenprodil (1.5, 3 and 6 mg/kg/day, i.p.) reduced the increases in myocardial oxygen demand induced by intracerebral L-glutamate in a dose-related manner. Interestingly, ifenprodil also reduced in a dose-dependent manner the maximum values of the oxygen demand indices reached during the central nervous system stimulation. These results indicate that the long-term treatment with ifenprodil can reduce the myocardial oxygen consumption induced by central nervous system stimulation without significant depression of the resting cardiac function. This favourable effect of ifenprodil is in fact a consequence of the association of mild inhibitory effects on the three parameters taken into account in the triple product index of myocardial oxygen consumption.

Autonomic dysregulation in panic disorder and in post-traumatic stress disorder: application of power spectrum analysis of heart rate variability at rest and in response to recollection of trauma or panic attacks

Power spectral analysis (PSA) of heart rate variability (HRV) offers reliable assessment of cardiovascular autonomic responses, providing a 'window' onto the interaction of peripheral sympathetic and parasympathetic tone. Alterations in HRV are associated with various physiological and pathophysiological processes, and may contribute to morbidity and mortality. Previous studies of posttraumatic stress disorder (PTSD) found lower resting HRV in patients compared to controls, suggesting increased sympathetic and decreased parasympathetic tone. This article describes the analysis of HRV at rest and after psychological stress in panic disorder (PD) patients, in an enlarged sample of PTSD patients, and in healthy control subjects. Standardized heart rate (HR) analysis was carried out in 14 PTSD patients, 11 PD patients and 25 matched controls. ECG recordings were made while subjects were resting ('rest 1'), while recalling the trauma implicated in PTSD, or the circumstances of a severe panic attack, as appropriate ('recall'), and again while resting ('rest 2'). Controls were asked to recall a stressful life event during recall. While both patient groups had elevated HR and low frequency (LF) components of HRV at baseline (suggesting increased sympathetic activity), PTSD patients, unlike PD patients and controls, failed to respond to the recall stress with increases in HR and LF. HRV analysis demonstrates significant differences in autonomic regulation of PTSD and PD patients compared to each other and to control subjects. HRV analysis may augment biochemical studies of peripheral measures in these disorders.

Cardiac arrhythmias and left ventricular hypertrophy in dipper and nondipper patients with essential hypertension

To evaluate the behavior of cardiac arrhythmias in dipper and nondipper hypertensive patients, 48-h ambulatory blood pressure monitoring, 24-h Holter electrocardiogram recording and echocardiographic studies were performed in 56 untreated outpatients with essential hypertension. These patients were divided into 2 groups according to the presence (dipper, n=33) or absence (nondipper, n=23) of reduction of both systolic and diastolic blood pressure during nighttime by an average of more than 10% of daytime blood pressure. Mean 48-h systolic and diastolic blood pressures did not differ between the 2 groups. Nondipper patients had a significantly larger left atrial dimension (31.9+/-3.8 vs 35.6+/-3.7 mm; p<0.01), left ventricular mass index (114+/-26 vs 136+/-36 g/m2; p<0.05), as well as a larger number of total supraventricular (16+/-19 vs 89+/-197 beats; p<0.05) and ventricular ectopic beats (7+/-14 vs 47+/-96 beats; p<0.05) during daytime as compared with dippers. In conclusion, nondipper hypertensive patients are likely to experience supraventricular and ventricular arrhythmias more frequently than dippers. A blunted nocturnal blood pressure fall may be involved in the appearance of cardiac arrhythmias in patients with essential hypertension.

Prevention of coronary heart disease. Part II. Secondary prevention, detection of subclinical disease, and emerging risk factors

The prevention of CHD should be a major priority among primary care physicians and subspecialists who have any dealing with the cardiovascular system. There is ample evidence from epidemiologic studies for the impact of specific risk factors on CHD events. There is also ample evidence from observational studies and clinical trials that interventions of lifestyle and pharmacologic therapy can decrease morbidity and mortality from CHD before or after the first event. It behooves the physician who wishes to practice good medicine to understand the pathophysiologic roles of the risk factors and the evidence from epidemiologic studies and clinical trials for their association with cardiovascular disease. It is important to determine the efficacy of interventions, both lifestyle and pharmacologic, in modifying CHD risk. To be effective in doing so, the practicing physician has to have the motivation to determine target goals for risk factor modification in each patient, to understand the patient's own motivations in modifying risk factors, and to define clearly with the patient the expectations of such interventions. Although there are guidelines for risk factor modification in modification of cholesterol and in hypertension, the periodic renewal of these guidelines reflects the changing concepts of risk and its modification. A cardiovascular risk factor intervention categorization is presented in Table 12. The physician must be convinced that such intervention is beneficial to the patient, cost-effective, and thus fulfills the expectations of medical practice. The practice of medicine in the evaluation and treatment of coronary heart disease has always been challenging and stimulating. The prevention of CAD disease should ultimately provide the greatest accomplishment.

Impact of psychological factors on the pathogenesis of cardiovascular disease and implications for therapy

Recent studies provide clear and convincing evidence that psychosocial factors contribute significantly to the pathogenesis and expression of coronary artery disease (CAD). This evidence is composed largely of data relating CAD risk to 5 specific psychosocial domains: (1) depression, (2) anxiety, (3) personality factors and character traits, (4) social isolation, and (5) chronic life stress. Pathophysiological mechanisms underlying the relationship between these entities and CAD can be divided into behavioral mechanisms, whereby psychosocial conditions contribute to a higher frequency of adverse health behaviors, such as poor diet and smoking, and direct pathophysiological mechanisms, such as neuroendocrine and platelet activation. An extensive body of evidence from animal models (especially the cynomolgus monkey, Macaca fascicularis) reveals that chronic psychosocial stress can lead, probably via a mechanism involving excessive sympathetic nervous system activation, to exacerbation of coronary artery atherosclerosis as well as to transient endothelial dysfunction and even necrosis. Evidence from monkeys also indicates that psychosocial stress reliably induces ovarian dysfunction, hypercortisolemia, and excessive adrenergic activation in premenopausal females, leading to accelerated atherosclerosis. Also reviewed are data relating CAD to acute stress and individual differences in sympathetic nervous system responsivity. New technologies and research from animal models demonstrate that acute stress triggers myocardial ischemia, promotes arrhythmogenesis, stimulates platelet function, and increases blood viscosity through hemoconcentration. In the presence of underlying atherosclerosis (eg, in CAD patients), acute stress also causes coronary vasoconstriction. Recent data indicate that the foregoing effects result, at least in part, from the endothelial dysfunction and injury induced by acute stress. Hyperresponsivity of the sympathetic nervous system, manifested by exaggerated heart rate and blood pressure responses to psychological stimuli, is an intrinsic characteristic among some individuals. Current data link sympathetic nervous system hyperresponsivity to accelerated development of carotid atherosclerosis in human subjects and to exacerbated coronary and carotid atherosclerosis in monkeys. Thus far, intervention trials designed to reduce psychosocial stress have been limited in size and number. Specific suggestions to improve the assessment of behavioral interventions include more complete delineation of the physiological mechanisms by which such interventions might work; increased use of new, more convenient "alternative" end points for behavioral intervention trials; development of specifically targeted behavioral interventions (based on profiling of patient factors); and evaluation of previously developed models of predicting behavioral change. The importance of maximizing the efficacy of behavioral interventions is underscored by the recognition that psychosocial stresses tend to cluster together. When they do so, the resultant risk for cardiac events is often substantially elevated, equaling that associated with previously established risk factors for CAD, such as hypertension and hypercholesterolemia.

Pyridostigmine blunts the increases in myocardial oxygen demand elicited by the stimulation of the central nervous system in anesthetized rats

The purpose of the present work was to verify the effect of pyridostigmine bromide, a reversible cholinesterase inhibitor, on the increases in cardiac work and myocardial oxygen demand produced by central sympathetic stimulation in pentobarbital-anesthetized Wistar rats. The pharmacological stimulation of the central nervous system with L-glutamate (1 mg/kg, intracerebroventricular) elicited marked increases in arterial pressure, dP/dt(max), rate-pressure product, and triple product, reproducing the cardiovascular alterations observed during physical effort and stressful situations. The oral administration of pyridostigmine bromide (5, 10 and 20 mg/kg) 2 hours before central stimulation blunted the increases in mean arterial pressure, dP/dt(max), and triple product elicited by glutamate (29, 28 and 57% for 5 mg/kg; 26, 23 and 46% for 10 mg/kg and 19, 17 and 37% for 20 mg/kg, respectively) when compared to the control group (41, 49 and 106%, respectively; p < 0.05). Our results also showed that the activity of plasmatic cholinesterase was effectively inhibited by pyridostigmine bromide. In conclusion, the increases in endogenous acetylcholine induced by cholinesterase inhibition blunted the centrally-evoked increases in myocardial oxygen demand in anesthetized rats. This effect could represent a cardioprotective action in a situation of ischemic heart disease.

Cholinergic stimulation with pyridostigmine blunts the cardiac responses to mental stress

Mental stress may induce myocardial ischemia and ventricular arrhythmia in patients with coronary artery disease, and cholinergic stimulation is a potential protective mechanism. The purpose of this study was to determine the effect of pyridostigmine bromide (PYR), a reversible cholinesterase inhibitor, on the cardiac responses to a mental stress challenge. Twelve healthy young volunteers were submitted to a mental stress test (arithmetic test) 2 hours after the oral administration of either placebo or PYR (45 mg) on two separate days, following a randomized crossover double-blind protocol. Heart rate was reduced after both placebo and PYR (p < 0.05), but the cardiac responses to the mental stress were lower with PYR (p < 0.05): mean RR interval (mean +/- SE)-placebo: 730 +/- 19 msec; PYR: 769 +/- 21 msec; Peak systolic pressure-placebo: 129 +/- 4 mmHg; PYR: 124 +/- 3 mmHg; Peak diastolic pressure-placebo: 92 +/- 3 mmHg; PYR: 89 +/- 4 mmHg; Mean rate-pressure product-placebo: 10,496 +/- 412 bpm x mmHg; PYR: 9,746 +/- 383 bpm x mmHg. In conclusion, 45 mg of pyridostigmine blunted the pressor and chronotropic responses to mental stress in healthy young subjects.

Preoperative metoprolol improves cardiovascular stability and reduces oxygen consumption after thoracotomy

BACKGROUND

Increased sympathetic activity perioperatively and associated cardiovascular effects play a central role in cardiovascular complications. High thoracic epidural blockade attenuates the sympathetic response, but even with complete pain relief, haemodynamic and endocrine responses are still present. Beta-adrenoceptor blockade is effective in situations with increased sympathetic activity. This study was designed to evaluate the perioperative haemodynamic effect of preoperative beta-blockade and its influence on the haemodynamic aspects of the surgical stress response.

METHODS

Thirty-six otherwise healthy patients undergoing elective thoracotomy for lung resection were randomised double-blinded to receive either 100 mg metoprolol or placebo preoperatively. Anaesthesia was combined high thoracic epidural block and general anaesthesia. The epidural analgesia was continued during recovery. Patients were monitored with ECG, pulse oximetry, invasive haemodynamic monitoring, arterial blood gases and electrolytes.

RESULTS

After induction of anaesthesia the mean arterial pressure (MAP) decreased in both groups, and decreased further in the placebo group after initiation of the epidural block. The heart rate (HR) was slightly less throughout the observation period after metoprolol. Peroperatively, the only difference in measured haemodynamics was a marginally higher MAP after metoprolol. Postoperative cardiac index (CI) was lower with a lower variability and cardiac filling pressures were slightly higher in the metoprolol group. The oxygen consumption index was higher after placebo throughout the observation period, with no difference in the oxygen delivery.

CONCLUSION

We found that preoperative beta-blockade during combined general anaesthesia and high thoracic epidural blockade stabilised perioperative HR and CI and decreased total oxygen consumption.

QT interval dynamics and heart rate variability preceding a case of cardiac arrest

A 71 year old man with hypertensive heart disease and chronic renal failure was wearing a Holter monitor when he had a cardiac arrest. He had ventricular fibrillation (VF) and died despite prompt resuscitation. In the 15 minutes preceding the VF there was a sudden increase in heart rate, followed by a brief period of atrial fibrillation leading to ventricular tachycardia, which in turn rapidly degenerated into VF. The QT interval and heart rate variability were studied half hourly over the seven hours preceding the cardiac arrest, using a computerised Holter system. A further detailed analysis was performed over the final hour before the cardiac arrest. An abrupt increase in the steepness of the QT/RR slope, a prolonged QTc, and a reduction in the heart rate variability were observed in the interval that immediately preceded the onset of the terminal rhythm disturbance.

Palpitations and lifestyle: impact of depression and self-rated health. The Nordland Health Study

On the basis of a questionnaire in a population study in the county of Nordland, Norway, the prevalence of palpitations and its associations to some lifestyle factors, depression and self-rated health were analysed. All the 10,497 residents aged 40 to 42 years were invited to participate, 82% attended, 87% of the attenders returned a questionnaire by mail, and 6436 subjects were included in this report. The prevalence of palpitations was 15% in men and 25% in women. Palpitations were significantly associated with coffee consumption, smoking, alcohol intoxication, physical inactivity, depression and poor self-rated health in the univariate analyses. In a logistic regression analysis, the relations between palpitations and lifestyle were weakened. Significant predictors for palpitations were depression and poor self-rated health in both sexes, in addition to heavy coffee drinking and physical inactivity in men and alcohol intoxication in women. In conclusion, palpitations were more firmly linked to depression and self-evaluated health than to lifestyle.