Mental stress, arrhythmias and sudden death

The cardiovascular risks of physical activity

The incidence of sudden death, serious arrhythmias, and myocardial infarction in connection with both recreational and rehabilitative physical activity is small. However, the incidence of e.g. sudden death is several times higher in exercise than at other times. This relative risk is highest in middle-aged men, and higher in strenuous than in nonstrenuous exercise. In the vast majority of the cases the underlying cause is advanced coronary heart disease, which in large proportion of the cases has been asymptomatic and has allowed regular strenuous training. Attempts to prevent the complications by special large scale screening programs would be ineffective and individual counselling limited by lack of resources. These measures should, however, be used in selected groups and individuals. Another approach is to inform the exercisers and their families at large by systematic, well-planned and repeated messages of the risks of physical activity, of the symptoms and findings indicating this risk, of the individual and environmental factors increasing the risk, and of the necessary measures to be taken to minimize the risk. Even if all available measures at present were used, the cardiovascular complications of physical activity could not be totally prevented. Fortunately, preliminary evidence suggests that at population level the cardiovascular hazards of physical activity are outweighed by its cardiovascular benefits.

Understanding the association between socioeconomic status and physical health: do negative emotions play a role?

In this article, the authors evaluate the possible roles of negative emotions and cognitions in the association between socioeconomic status (SES) and physical health, focusing on the outcomes of cardiovascular diseases and all-cause mortality. After reviewing the limited direct evidence, the authors examine indirect evidence showing that (a) SES relates to the targeted health outcomes, (b) SES relates to negative emotions and cognitions, and (c) negative emotions and cognitions relate to the targeted health outcomes. The authors present a general framework for understanding the roles of cognitive-emotional factors, suggesting that low-SES environments are stressful and reduce individuals' reserve capacity to manage stress, thereby increasing vulnerability to negative emotions and cognitions. The article concludes with suggestions for future research to better evaluate the proposed model.

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.

Gender and psychosomatic aspects of ischemic heart disease

While women and their doctors have traditionally worried about mortality from breast and gynecological malignancies, over the past 5 years they have come to realize that ischemic cardiac disease (IHD) is the number one killer of women in most Western countries. This has led to public and professional education campaigns and a new emphasis on gender and gender-specific research in IHD. Unfortunately, this literature remains poorly developed and much work remains to be done. Even in samples in which there may be sufficient numbers to allow for the evaluation of gender and gender differences, these important analyses have often been overlooked. This article provides a review of what is known about gender and gender differences in psychosocial and behavioral issues in IHD.

Sudden unexplained death syndrome

A retrospective investigation of 51 cases of sudden unexplained death syndrome (SUDS) reported to the Medico-Legal Centre in Dammam during the period January 1995 to June 1997 was carried out. The vast majority of SUDS victims were Indians (43%). The study reports SUDS in non-East Asian subjects, including indigenous Saudis, for the first time. Autopsy examination was carried out on 22 subjects and did not reveal any significant pathological lesions which could fully explain the sudden death. However, seven cases showed mild to moderate cardiac hypertrophy (of whom two had mild to moderate coronary stenosis), and another four showed a similar degree of coronary narrowing without any evidence of myocardial hypertrophy. Severe pulmonary congestion and alveolar haemorrhage were noticed in 18 of the autopsied cases. Microbiological tests were performed on different specimens from 27 subjects and showed significant bacterial growth in seven cases. The paper reviews different hypotheses explaining SUDS and suggests areas of further study in such deaths.

Schizophrenia and sudden death: a medical examiner case study

This study reviews the causes of sudden death of 66 schizophrenic patients who presented to the Office of the Chief Medical Examiner (OCME) for the State of Maryland over a 3-year period from 1994 through 1996. We identified an increased incidence of suicide compared with the general population of OCME cases. This observation is consistent with reports by other investigators. The majority of the deaths were the result of natural diseases, mostly atherosclerotic cardiovascular disease. Accidents, suicides, and 1 homicide were also present in this group.

Cardiovascular death from panic disorder and panic-like anxiety: a critical review of the literature

Several symptoms of panic disorder mimic those of cardiovascular diseases and patients with this disorder frequently consult physicians with the fear of dying from a heart attack. The salient question is: Can the patient with panic disorder die from the cardiovascular consequences of his/her panic attacks? We critically review the six studies that have examined the association between panic disorder (or panic-like anxiety) and cardiovascular mortality or complications associated with the cardiovascular system. We then briefly review the evidence by which mechanisms panic may be linked to cardiovascular mortality and conclude with proposed guidelines for patient management.

Sudden infant death syndrome: a proposed discovery

Sudden cardiac death is a leading cause of fatality in the industrially developed world. Sudden infant death syndrome, has not hitherto been regarded as the same disease. However, the 55% reduction in the recorded rate of death from sudden infant death syndrome following the removal of stress-related problems caused by babies sleeping on their stomachs and overheating from tight and heavy clothing has, I propose, revealed that the babies may be dying from a similar stress-related cause, which can be prevented.

Abnormal passive head-up tilt test in subjects with symptoms of anxiety power spectral analysis study of heart rate and blood pressure

Previous reports that subjects with anxiety symptoms are at higher risk of sudden death may imply that anxiety induces stable sympathetic hyperactivity. To address this subject, in persons with and without anxiety symptoms, we evaluated autonomic nervous system activity by power spectral analysis of heart-rate and arterial-pressure variability at baseline (rest) and after sympathetic stress (tilt). The 117 subjects selected (56 men and 61 women, age range 23-87 years) were subdivided by questionnaire into three groups: 49 subjects (mean age 55.8+/-2.8 years) had no anxiety symptoms; 36 (mean age 56.8+/-3.6 years) had one anxiety symptom; and 32 (mean age 55.0+/-2.9 years) had two or more anxiety symptoms. Power spectral analysis recognizes three main components: high frequency (HF), chiefly reflecting vagal efferent activity; low frequency (LF), reflecting sympathetic activity; and very-low-frequency (VLF). The ratio of low- to high-frequency powers (LF:HF) of heart rate variability provides a measure of sympathovagal balance. Power spectral analysis showed that subjects with two or more anxiety symptoms had significantly lower resting values for all power spectral components of heart rate variability: total power (TP), VLF, LF, and HF than did symptomless controls (P<0.05). The highest anxiety-score groups also had a higher baseline LF:HF than the other two groups (P<0.05). Their resting LF:HF ratio correlated positively with anxiety symptom scores (r=0.72, P<0.0001). Tilt induced opposite results: the highest anxiety-score groups had a significantly lower LF:HF ratio; the ratio correlated inversely with their anxiety scores (r=-0.69; P<0.0001). Recordings of resting systolic arterial pressure variability showed that the group with two or more anxiety symptoms had significantly higher LF power (P<0.05) than symptomless controls. Our findings suggest that persons with high anxiety scores have baseline cardiac sympathetic hyperactivity. They also have low heart-rate variability, possibly explaining their susceptibility to sudden cardiac death.

Symptoms of anxiety and risk of coronary heart disease. The Normative Aging Study

BACKGROUND

Several studies have suggested an increased risk of fatal coronary heart disease (CHD) among patients with panic disorder, phobic anxiety, and other anxiety disorders. We prospectively examined this association in the Normative Aging Study.

METHODS AND RESULTS

An anxiety symptoms scale was constructed out of five items from the Cornell Medical Index, which was administered to the cohort at baseline. During 32 years of follow-up, we observed 402 cases of incident coronary heart disease (137 cases of nonfatal myocardial infarction, 134 cases of angina pectoris, and 131 cases of fatal CHD: made up of 26 cases of sudden cardiac death and 105 cases of nonsudden death). A nested case-control design (involving 1869 control subjects who remained free of diagnosed CHD) was used to assess the association between anxiety and risk of CHD. Compared with men reporting no symptoms of anxiety, men reporting two or more anxiety symptoms had elevated risks of fatal CHD (age-adjusted odds ratio [OR] = 3.20, 95% confidence interval [CI]: 1.27 to 8.09), and sudden death (age-adjusted OR = 5.73, 95% CI: 1.26 to 26.1). The multivariate OR after adjusting for a range of potential confounding variables was 1.94 (95% CI: 0.70-5.41) for fatal CHD and 4.46 (95% CI: 0.92-21.6) for sudden death. No excess risks were found for nonfatal myocardial infarction or angina.

CONCLUSIONS

These data suggest an association between anxiety and fatal coronary heart disease, in particular, sudden cardiac death.

Identification of a cortical site for stress-induced cardiovascular dysfunction

The evidence indicating that the insular cortex is a likely candidate to mediate stress-induced cardiovascular responses is reviewed. Both neuroanatomical and electrophysiological investigations demonstrate that the insular cortex receives an organized representation of visceral information. In addition, the insular cortex also receives highly processed association cortex information. The insular cortex is also highly interconnected with many subcortical limbic and autonomic regions. This combination of sensory input and limbic/autonomic connectivity would be necessary to permit the insular cortex to be a critical site for the integration of emotional and autonomic responses. Stimulation of the insular cortex elicits specific cardiovascular and autonomic responses from discrete sites. Phasic stimulation entrained to the cardiac cycle is even capable of causing severe arrhythmias. The efferent pathways and some of the neurotransmitter mechanisms have determined. It appears that the lateral hypothalamic area is the primary site of synapse for responses originating in the insular cortex and this information is relayed by NMDA glutamatergic receptors and modulated by neuropeptides including neuropeptide Y, neurotensin, leu-enkephalin and dynorphin. Finally, a rat stroke model, which includes the insular cortex in the infarct region indicates that disruption of the insula can produce substantial cardiac and autonomic abnormalities, which might be similar to those produced by stress. Some of the chronic neurochemical changes, including increases in opioids, neuropeptide Y and neurotensin in the central nucleus of the amygdala, which might be mediating these cardiovascular disturbances, have been determined.

Sudden unexpected nocturnal deaths among Thai immigrant workers in Singapore. The possible role of toxigenic bacteria

Sudden Unexpected Nocturnal Deaths (SUND) occur in young, apparently healthy immigrant workers from Thailand, the Philippines and Bangladesh living among ex-patriot labour forces in countries such as Singapore and Saudi Arabia. Several factors associated with these deaths are similar to those observed for Sudden Infant Death Syndrome (SIDS): sleep related and mainly nocturnal occurrence; no prodromal illnesses other than mild respiratory tract infection; exposure to cigarette smoke; absence of invasive microorganisms at autopsy. The hypotheses proposed to explain these deaths in adults are examined. Based on our studies of the role toxigenic bacteria might play in some cases of SIDS, we suggest a new approach to the investigation of SUND.

Prospective study of phobic anxiety and risk of coronary heart disease in men

BACKGROUND

To examine prospectively the association between self-reported symptoms of phobic anxiety and subsequent risk of coronary heart disease, a 2-year follow-up study was conducted of a cohort of 33,999 US male health professionals, aged 42 to 77 years in 1988, who were free of diagnosed cardiovascular disease at baseline. Levels of phobic anxiety were assessed using the Crown-Crisp index, a short, diagnostic self-rating scale used for common phobias. Main outcomes were incidents of coronary heart disease consisting of nonfatal myocardial infarction (MI) and fatal coronary heart disease (CHD).

METHODS AND RESULTS

One hundred sixty-eight incident cases of CHD occurred during 2 years of follow-up (128 cases of nonfatal MI and 40 cases of fatal CHD). The age-adjusted relative risk of fatal CHD among men with highest levels of phobic anxiety (scoring 4 or higher on the Crown-Crisp index) was 3.01 (95% confidence interval, 1.31 to 6.90) compared with men with the lowest levels of anxiety (scoring 0 or 1 on the phobia index). Risk of fatal CHD increased with levels of phobic anxiety (P trend = .002). When fatal CHD was further categorized into sudden and nonsudden coronary death, the excess risk was confined to sudden death (relative risk among men scoring 3 or higher on the phobia index was 6.08; 95% confidence interval, 2.35 to 15.73). No association was found between phobic anxiety and risk of nonfatal MI. These findings remained essentially unchanged after adjusting for a broad range of cardiovascular risk factors.

CONCLUSIONS

The specificity, strength, and dose-response gradient of the association, together with the consistency and biological plausibility of the experimental and epidemiologic evidence, support a strong causal association between phobic anxiety and fatal CHD.

The long-term reproducibility of clinical tests of autonomic cardiovascular function in normal man

Tests for the integrity of autonomic cardiovascular reflexes have been widely used in the clinic and in space physiology for decades. However, whereas some information on the short-term reproducibility of such tests are available, little is known about their long-term reproducibility. The work in this study was, therefore, directed towards assessing intra- and inter-subject variations in responses (heart rate, mean arterial blood pressure, forearm blood flow and forearm vascular conductance) to cortical arousal, cold face stimulation and lower body negative pressure (at 10, 30 and 50 mmHg) in eleven healthy male subjects (aged between 22 and 45 years). Subjects were studied repeatedly (each month) over a 6-month period. It was found that forearm vascular conductance responses to cold face stimulation were the most reproducible (mean coefficient of variation 10.9%), and with diminishing reproducibility curve responses to lower body negative pressure at 50 mmHg (mean coefficient of variation 12.4%), lower body negative pressure at 30 mmHg (mean coefficient of variation 18.9%), lower body negative pressure at 10 mmHg (mean coefficient of variation 28.0%), and responses to cortical arousal (mean coefficient of variation 39.6%). Generally, subjects who showed the largest responses to cold face stimulation also showed the largest responses to the other tests, and vice versa. It is concluded that there is intra-individual variability in the responsiveness and reproducibility of cardiovascular tests and that the cardiovascular responses to cold face stimulation and lower body negative pressure at 50 mmHg are the most reproducible.

The sudden unexplained death syndrome in epilepsy: demographic, clinical, and postmortem features

Sudden unexplained death syndrome (SUDS) accounts for about 10% of deaths in patients with epilepsy. It is associated with subtherapeutic postmortem serum antiepileptic drug (AED) levels but no anatomic cause of death on autopsy. The mechanisms of death are not known. We investigated 44 cases of SUDS for details of seizure history, treatment, medical and psychological history, events at the time of death, and postmortem findings. Cases of status epilepticus, drowning or other identifiable causes of death were excluded. Two groups emerged: five children with uncontrolled seizures receiving multiple AEDs and good compliance with medications, and 39 adults with less frequent seizures, often receiving monotherapy, but noncompliant with medications. Four children (80%) but only one adult (3%) had fully therapeutic postmortem AED levels. Sixty-three percent of adults recently had experienced an unusually stressful life event. Investigation of the circumstances at the time of death suggested two possible modes of death: (a) a seizure with an immediately fatal arrhythmia, or, (b) a seizure, recovery, then delayed secondary respiratory arrest or arrhythmia. Even though the mechanisms of death are unknown, the risk of SUDS may be reduced by encouraging patients to be compliant with medications, especially in times of unusual life stress.

The conduction system of the swine heart

Although the pig has been used as an experimental model for ischemic heart disease and sudden death, relatively little is known about the anatomy of the conduction system (CS) of this animal. We attempted to correlate electrophysiologic and anatomic differences between the pig and human CS. Invasive electrophysiologic studies were performed in five healthy anesthetized pigs. In contrast to the adult human, the pig has sinus tachycardia, shortened PR and H-V intervals, and a relatively short sinoatrial conduction time. Compared with the human CS, serial sections of the CS of pig hearts showed the following differences: (1) the atrioventricular node is located more to the right of the summit of the ventricular septum; (2) the penetrating bundle is very short, and the bifurcation of the bundle into bundle branches occurs more proximally; (3) there is more connective tissue and less elastic tissue; and (4) there is a copious amount of nerve fibers (about 50 percent throughout the CS). The presence of the abundant neural tissue implies that there is an important neurogenic component to conduction in the pig. Because of the above differences from the human, the pig should be used with caution as an experimental model in ischemic heart disease and sudden death where arrhythmias are studied.

Ideology in medical science: class in the clinic

The class character of medicine is most easily discerned in the inequitable organization of health services. Capital's shaping of the patterns of disease and our medical/scientific responses is less apparent but equally strong. We illustrate this point by reviewing some recent history of cardiovascular diseases and therapies. Hitherto unknown afflictions have become commonplace. Our diagnostic and therapeutic concepts are the crystallization of a long history of scientific effort--an effort dominated and directed by capitalist imperatives. The work of the clinician rests on this scientific substrate, and recognition or rejection of its class nature provides a potential basis for a new medical science but not the needed results. The socialist transformation of medicine will require a recognition of the capitalist specificity of current science, and the painstaking construction of alternative modes of thought.

Night terrors and sudden unexplained nocturnal death

A high incidence of sudden unexplained nocturnal deaths has been reported among young Asian males. These deaths are known as Pokkuri in Japan, Bangungut in the Philippines and Sudden Unexplained Nocturnal Death in the United States. Post mortem analysis has demonstrated cardiac conduction defects in many of the victims. Careful review of the terminal events surrounding these deaths suggests that the victims suffered from night terrors. Night terrors are a sleep disorder characterized by vocalization, motor activity, a nonarousable state, and severe autonomic discharge. The proposed recognition of both night terrors and cardiac anomalies in these patients offers a pathophysiologic mechanism for their sudden death.

Thoracic epidural anaesthesia decreases the incidence of ventricular arrhythmias during acute myocardial ischaemia in the anaesthetized rat

The aim of the present investigation was to study the effect of high thoracic epidural anaesthesia (TEA) on the incidence of ventricular arrhythmias after ligation of the left coronary artery in chloralose-anaesthetized rats. Forty animals were randomly assigned to receive either 40-50 microliter of bupivacaine (5 mg/ml) or saline in implanted thoracic epidural catheters. TEA decreased mean arterial pressure (MAP) from 118 +/- 5 mmHg to 72 +/- 4 mmHg and heart rate (HR) from 450 +/- 9 to 387 +/- 8 beats/min, while epidural saline did not affect MAP and HR. In both groups coronary artery ligation induced a transient decrease in MAP within the first 5-10 min after ligation. In the control group HR increased, during the 30-min post-ligation period, from 453 +/- 9 to 474 +/- 10 beats/min (P less than 0.05) while no significant change was seen in the TEA group. In both groups the mortality rate was 10%. In the TEA group 30% and in the control group 0% had normal sinus rhythm during the recording period (P less than 0.001). The incidence of ventricular fibrillation and/or tachycardia was significantly lower (P less than 0.05) in the TEA group (20%) compared to the control group (53%). The incidence of ventricular extrasystoles did not differ between the two groups. We conclude that TEA-induced blockade of sympathetic afferents and efferents may offer protection against malignant ventricular arrhythmias in the early phase of acute myocardial infarction.

Phobic anxiety and ischaemic heart disease

A prospective study of the relation between scores on the six subscales of the Crown-Crisp experiential index and subsequent incidence of ischaemic heart disease was undertaken among participants in the Northwick Park heart study. Results from 1457 white men aged 40-64 at recruitment showed that phobic anxiety was strongly related to subsequent major ischaemic heart disease (fatal and non-fatal events combined) when other associated variables were taken into account. The phobic anxiety score alone remained significantly associated with ischaemic heart disease when scores on all the subscales were included in the analysis. Phobic anxiety seemed to be particularly associated with fatal ischaemic heart disease but was not associated with deaths from other causes and was no higher in those with a pre-existing myocardial infarction at recruitment than in those without. There was a consistent increase in risk of fatal ischaemic heart disease with score on the phobic anxiety subscale. The relative risk for those whose score was 5 and above was 3.77 (95% confidence interval 1.64 to 8.64) compared with those whose score was 0 or 1. The 49 participants with evidence of myocardial infarction at recruitment had higher scores on the subscales for free floating anxiety and functional somatic complaint. The Crown-Crisp experiential index is simple to fill out and acceptable to patients. When the results are combined with other known risk factors it may be of use in defining high risk subjects and in planning strategies for prevention.

Sudden death and vigorous exercise--a study of 60 deaths associated with squash

The circumstances surrounding 60 sudden deaths (59 men, one woman) associated with squash playing are described. The mean age (SD) of those who died was 46 (10.3) years (range 22-66 years). Necropsy reports were available in 51. The certified cause of death was coronary artery disease in 51 cases, valvar heart disease in four, cardiac arrhythmia in two cases, and hypertrophic cardiomyopathy in one case. There were only two deaths from non-cardiac causes. Forty five of those who died had reported prodromal symptoms, the most common of which was chest pain, and 22 were known to have had at least one medical condition related to the cardiovascular system during life, the most common of which was systemic hypertension (14 subjects). Those dying from coronary artery disease had a high frequency of risk factors. Some of these deaths might have been prevented by appropriate counselling of players after prospective medical screening, which would have detected most of the patients with overt cardiovascular disease and some of those with subclinical coronary artery disease.

Platelet activation and secretion associated with emotional stress

Platelets are believed to play a role in the pathogenesis of atherosclerosis and of the vascular obstruction that causes the acute complications of coronary artery disease. Since specific behavioral patterns appear to be related to the development of coronary artery disease and since emotional stress may predispose an individual to acute cardiovascular ischemia, it was hypothesized that platelet activation by catecholamines might be involved in these events. To study emotional stress, plasma samples were obtained from 61 senior medical residents immediately before they were to speak in public. There were significant increases in the plasma concentrations of the platelet-secreted proteins platelet factor 4 and beta-thromboglobulin and epinephrine and norepinephrine immediately before speaking, which demonstrates that platelet activation and secretion occur in association with this type of emotional stress. Four trials were carried out to study the mechanism for this observed platelet secretion: (1) phenoxybenzamine, (2) propranolol, (3) 650 mg aspirin, and (4) 80 mg aspirin were given several hours before the public speaking engagement. Neither phenoxybenzamine nor propranolol in doses that blocked the hemodynamic effects of alpha 1- and beta 1-adrenergic stimulation modified platelet secretion. Aspirin also did not block platelet secretion, which suggests that platelets were not being stimulated through a cyclooxygenase-dependent pathway. This study provides direct evidence of platelet secretion in vivo in association with emotional stress, and underscores the potential importance of platelet activation and secretion in the acute events that occur in patients with vascular disease.

Exercise and heart disease. Epidemiology of the "exercise hypothesis"

The "exercise hypothesis" states that exercise protects against coronary heart disease. Reviewed herein is the epidemiologic evidence for and against the "exercise hypothesis." The weight of evidence supports the view that exercisers have a lower risk of coronary disease, but that vigorous exercise cannot always prevent progression of coronary atherosclerosis and does increase the risk of sudden death in persons with advanced coronary atherosclerosis. It is concluded that the "exercise hypothesis" is plausible, even likely, but still unproved.

Cardiovascular effects of potential occupational hazards

Cardiovascular effects of potential occupational hazards have received relatively little attention. The major inhalant occupational exposures of concern are carbon disulfide, nitrates, halogenated hydrocarbons and carbon dioxide. Occupational exposure to certain trace metals may also be associated with adverse cardiovascular effects. Of concern is potential toxicity from cobalt, antimony, lead, cadmium and arsenic. Potential physical hazards exist in association with noise, heat and radiofrequency radiation. In most instances, the data are suggestive rather than conclusive. Further epidemiologic studies with careful control for potentially complicating factors, such as baseline differences in blood pressure, cigarette smoking habits and age, are needed. In some areas where epidemiologic studies have provided clues, the mechanisms of action of potential occupational hazards require further basic scientific investigation.