Relationship between stress and coronary heart disease

BACKGROUND

Coronary heart disease is the leading cause of death worldwide and accounts for 13.7% of deaths in countries like Pakistan. Its association with stress has not been well considered in our setup. Patients with coronary artery disease admitted for coronary artery bypass grafting may have a high prevalence of stress that might increase the risk of adverse outcomes.

METHODS

60 patients with coronary artery disease admitted to the Civil Hospital Karachi for coronary artery bypass graft surgery from January 1 to March 31, 2012, were evaluated using a stress evaluation scale.

RESULTS

Stress of varying degrees was found to be a significant independent risk factor in patients with coronary heart disease. Analysis of our collected sample of patients with stress showed 60% with high stress (p = 0.025) and 36.7% moderate stress (p = 0.0025). An appreciable relationship was found between stress and patient age, sex, body mass index, blood group, and the incidence of myocardial infarction.

CONCLUSION

Our study found evidence of an independent causative association between psychological stress and coronary heart disease, of a similar order to the more conventional coronary heart disease risk factors.

"Stress" and coronary heart disease: psychosocial risk factors

An Expert Working Group of the National Heart Foundation of Australia undertook a review of systematic reviews of the evidence relating to major psychosocial risk factors to assess whether there are independent associations between any of the factors and the development and progression of coronary heart disease (CHD), or the occurrence of acute cardiac events. The expert group concluded that (i) there is strong and consistent evidence of an independent causal association between depression, social isolation and lack of quality social support and the causes and prognosis of CHD; and (ii) there is no strong or consistent evidence for a causal association between chronic life events, work-related stressors (job control, demands and strain), Type A behaviour patterns, hostility, anxiety disorders or panic disorders and CHD. The increased risk contributed by these psychosocial factors is of similar order to the more conventional CHD risk factors such as smoking, dyslipidaemia and hypertension. The identified psychosocial risk factors should be taken into account during individual CHD risk assessment and management, and have implications for public health policy and research.

Influence of lifestyle, coping, and job stress on blood pressure in men and women

We designed this study to clarify the role of work stress on long-term blood pressure control and in particular to investigate whether perceived work stress directly affected resting blood pressure levels or whether there were indirect effects mediated by coping mechanisms and lifestyle. Men (n = 337) and women (n = 317) working in a government tax office completed questionnaires for assessment of work-related stress, coping strategies, and lifestyle. Seven resting blood pressure measurements were recorded serially on each of two occasions a week apart. Men had higher blood pressures (119.6/68.6 versus 110.9/65.6 mm Hg) than women; they used more "maladaptive" coping strategies, drank more alcohol, and ate less healthily but exercised more than women. There were no direct associations between measures of work stress and blood pressure. In univariate and regression analyses, both body mass index and lifestyle factors in the form of alcohol consumption, exercise, and diet were related to blood pressure in men and women. Various "adaptive" or "maladaptive" coping mechanisms were identified and independently related to both job stress and blood pressure levels. Women were more likely to use "healthier" or adaptive coping mechanisms than men. Thus, work stress per se had no direct effect on blood pressure, but the ways that individuals reported coping with stress were significantly related to blood pressure, with blood pressure elevation effects appearing to be mediated largely by dietary and drinking habits and physical inactivity. The results point to the need to target individual coping strategies and lifestyle as much as the working environment in workplace cardiovascular health promotion programs.

Type A behaviour in the Australian working population

The Type A behaviour pattern (TABP) has been widely researched in Australian studies and, in view of its increasing prominence beyond its original association with risk of coronary heart disease, is likely to be as widely researched in this country well into the future. The Jenkins Activity Survey (JAS), being the most comprehensive self-report instrument used to assess the TABP, appears to be the instrument of choice for the measurement of the TABP in Australia, particularly in epidemiological studies where large samples are involved, or in other studies where either the interview method is impractical or the researchers are untrained in its application. This paper presents normative data on the use of the JAS in the Australian context, derived from a series of empirical studies undertaken by the authors over the past decade. Sociodemographic correlates of these data are presented, and refinements of the JAS for future use are suggested.

Effects of adrenoreceptor antagonists and agonists on clearance of emulsion models of triacylglycerol-rich lipoproteins from plasma in rats

1. We previously found that adrenaline and noradrenaline exert essentially opposite effects on clearance from plasma of chylomicron-like emulsions injected intravenously in rats, suggesting mechanisms that may be implicated in the atherogenic effects of chronic stress and hypertension and conversely in the protective effect of regular exercise. 2. The mechanisms underlying the effects of adrenaline and noradrenaline have now been investigated. Chronic adrenergic blockade with either the alpha 1-receptor antagonist doxazosin or the beta-receptor antagonist propranolol slowed the clearance of labelled emulsion lipids from plasma of normal Wistar rats. The results with doxazosin were unexpected in view of its capacity to decrease plasma triglycerides in patients. 3. In spontaneously hypertensive rats (SHR) the clearance of triolein (TO) was very slow compared with normal Wistar rats. Emulsion TO clearance provides a measure of lipolysis by lipoprotein lipase, and a defect in clearance indicates either defective enzyme action or poor perfusion of capillary beds rich in enzyme. Defective enzyme activity in SHR was excluded, suggesting redistribution of blood flow away from skeletal muscle and adipose tissue. In SHR the TO clearance from injected chylomicron-like emulsions was improved by blockade with doxazosin compared with control untreated SHR. 4. The beta 2-adrenoreceptor agonist Fenoterol was infused intravenously during clearance of an injected lipid emulsion. Clearance of radiolabelled cholesteryl oleate (CO) was clearly slowed while there was a lesser reduction of TO clearance rate. Emulsion CO clearance provides a measure of the uptake of lipoprotein remnants by the liver, and a defect in clearance of CO indicates either defective ligand (apolipoprotein E)-receptor interaction or decreased perfusion of the splanchnic bed. Isoprenaline, a non-selective beta-adrenergic agonist, gave similar results. Both compounds reduced mean arterial pressure by about 20-40 mm Hg at the doses employed, indicating that the beta 1 (cardiac) effect of the isoprenaline was insufficient to offset its vasodilatatory effect on skeletal muscle arterioles (beta 2). 5. The alpha-agonist phenylephrine, at a dose which moderately raised mean arterial pressure, slowed clearance of both TO and CO for the first 12 min after injection of emulsion but at later time points clearances caught up with the controls. 6. Administration of a mixture of isoprenaline and phenylephrine produced definite enhancement of both TO clearance and CO clearance. The effect of the mixture was opposite to the effects of of either agonist alone, demonstrating clearly that direct effects on lipoprotein lipase activity or receptor mediated processes were not involved.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of adrenaline and noradrenaline on clearance of triacylglycerol-rich lipoproteins from plasma: studies with chylomicron-like lipid emulsions in rats

1. Adrenaline was infused intravenously in rats during the clearance from plasma of an injected lipid emulsion designed to model chylomicrons and the triacylglycerol-rich plasma lipoproteins. The clearance rates of emulsion radiolabelled triolein (TO) and cholesteryl oleate (CO) were both increased, suggesting that hydrolysis of lipoprotein triglycerides and clearance of remnants from plasma were increased. The distribution of radiolabels in tissues showed more TO in skeletal and cardiac muscle after adrenaline, while more CO was found in liver compared with controls. Lesser amounts of both labels were found in the spleens of treated rats. 2. In a similar experiment with noradrenaline, the clearance rate of emulsion CO was decreased. The removal of CO was retarded more than that of emulsion TO, which was not significantly affected, and CO label recovered in liver was significantly decreased, suggesting that the removal of remnants from plasma was slowed after noradrenaline. In experiments in which noradrenaline was infused continuously for 1 week the clearances of emulsion CO and TO were both reduced. 3. Our findings suggest possible connections between plasma catecholamines and the development of arteriosclerosis, in view of the atherogenicity of remnants of the triacylglycerol-rich plasma lipoproteins. Yet to be established is whether the linkage we have found between lipoprotein clearance, adrenaline and noradrenaline contributes to the atherogenic effects of chronic stress and for the protective effects of exercise.