Pathophysiology of acute coronary syndromes leading to acute myocardial infarction

Cold-related cardiac mortality in King County, Washington, USA 1980–2001

BACKGROUND

Studies have shown that cardiac deaths increase during the winter months and that death rates can be tightly predicted from temperature rather than other atmospheric phenomena such as barometric pressure, humidity, or pollution.

AIM

The object of this study is to examine the possible relationship between temperature and cardiac death rates in King County, Washington, USA and suggest possible public health measures that can decrease the number of cardiac deaths associated with cold exposure.

SUBJECTS AND METHODS

State death records show that 62,125 total out-of-hospital cardiac-related deaths among persons 55 years and older occurred in King County between 1980 and 2001. We use Poisson regression to examine the association between same-day daily average temperature and death rate after adjusting for seasonal effects.

RESULTS

We identified a significant negative association between daily average temperature and cardiac mortality among persons over 55 years of age. A 5 degrees C increase in temperature was associated with a decrease in death rate by a factor of 0.971 (95% CI: 0.961, 0.982).

CONCLUSION

Cold temperatures may be an important triggering factor in bringing on the onset of life-threatening cardiac events, even in regions with relatively mild winters. Public health efforts stressing cold exposure while out of doors may play a prominent role in encouraging a reduction in cold stress, especially among seniors and those already at higher risk of cardiac death.

Chest pain and associated symptoms of acute coronary syndromes

Coronary heart disease is the primary health risk for all Americans. Acute coronary syndromes (ACS) is the term used to denote any 1 of 3 clinical manifestations of coronary heart disease: unstable angina, non-ST elevation myocardial infarction, and ST-elevation MI. The major challenge to healthcare providers is the rapid and accurate identification of patients with ACS who would benefit from immediate thrombolysis or percutaneous coronary interventions. The purpose of this article is to describe the incidence, causes, risk factors, assessment, and diagnosis of patients presenting with ACS as well as current recommendations for nurses who treat patients with ACS.

"Vulnerable plaques" — ticking of the time bomb

Atherosclerosis and its sequelae are one of the leading causes of morbidity and mortality, especially in the developed nations. Over the years, treatment protocols have changed with the changing understanding of the disease process. Inflammatory mechanisms have emerged as key players in the formation of the atherosclerotic plaque. For the majority of its life span, the plaque develops silently and only some exhibit overt clinical manifestations. The purpose of this review is to examine the inherent properties of some of these "vulnerable" or symptomatic plaques. Rupture of the plaque is related to the thickness of the fibrous cap overlying the necrotic lipid core. A thin cap is more likely to lead to rupture. Multiple factors broadly grouped as the "determinants of vulnerability" are responsible for directly or indirectly influencing the plaque dynamics. Apoptosis is considered an important underlying mechanism that contributes to plaque instability. Inflammatory reactions within the plaque trigger apoptosis by cell–cell contact and intra cellular death signaling. Once started, the apoptotic process affects all of the components that make up the plaque, including vascular smooth muscle cells, endothelial cells, and macrophages. Extensive research has identified many of the key cellular and molecular regulators that play a part in apoptosis within the atherosclerotic lesion. This information will help us to gain a better understanding of the underlying mechanisms at the cellular and molecular level and enable us to formulate better therapeutic strategies to combat this disease.Key words: apoptosis, atherosclerosis, inflammation, plaque stability, vulnerable plaques.

Comparison of vascular smooth muscle cell apoptosis and fibrous cap morphology in symptomatic and asymptomatic carotid artery disease

The biological cascades that lead to carotid plaque disruptions and symptoms are largely unknown. Certain cellular events within the plaque might be responsible for destabilizing the plaque, though the popular belief is that the plaque size is directly related to symptoms. The aim of our study was to assess the morphology of the fibrous cap and apoptosis in the plaque and compare these two pathological features in symptomatic and asymptomatic carotid artery disease. Our work was carried out in plaques obtained following carotid endarterectomy performed for symptomatic disease (including hemispheric transient ischemic attacks, amaurosis fugax, or stroke) or asymptomatic high-grade severe stenosis. Scion images of Gomori's stained sections were used to measure fibrous cap thickness and area. TUNEL assay was performed to assess the extent of apoptosis. The results indicated that the area of the fibrous cap did not significantly correlate with the presence of symptoms. There was a higher percentage of apoptotic nuclei and the thinner fibrous cap in symptomatic plaques than in asymptomatic plaques. This finding suggests that these factors might be involved in destabilizing plaque, causing rupture and leading to symptomatic carotid disease.

Pharmacotherapeutic options for the management of myocardial infarction

The pharmacological treatment of acute coronary syndrome (ACS), including unstable angina, non-ST- and ST-segment elevation myocardial infarction (MI) is dynamic and continues to evolve. Expert guidelines based on the results of clinical trials for the management of different types of ACS have been published. In both ST-segment elevation and non-ST-segment elevation MI, aspirin/clopidogrel, heparin/low molecular weight heparin/direct thrombin inhibitors, beta-blockers and angiotensin converting enzyme inhibitors are part of the routine regimens. In patients with ST-segment elevation MI, eligibility for thrombolytic therapy needs to be determined and utilised as soon as possible. In patients with non-ST-segment elevation MI, the risks of thrombolytic therapy outweigh the benefits. The use of glycoprotein IIb/IIIa inhibitors has become increasingly important. The use of antihyperlipidaemic agents for the prevention of secondary events in both types of patients continue to be essential and the early aggressive use of lipid-lowering therapy also plays a role in improving endothelial function and stabilising atherosclerotic plaques.

Advanced cardiac life support for the new millennium

The American Heart Association has been the recognized source for Advanced Cardiac Life Support (ACLS) education for the past three decades. Since the first ACLS course, numerous revisions have been made to the management algorithms based on evolving scientific evidence. The last revisions made in August 2000 were the first international guidelines published. These guidelines reflect the intense review and analysis of scientific work and emphasize the importance of evidence-based therapies. This article outlines the major changes to ACLS guidelines for dysrhythmias, acute coronary syndromes, and acute stroke management.

The role of glycoprotein IIb/IIIa inhibition in the management of acute coronary syndromes

Recent advances in the understanding of the pathophysiology of thrombus formation and the role of platelet adhesion have led to a new pharmacologic era in cardiology. The advent of the glycoprotein IIb/IIIa inhibitor, primarily used in conjunction with percutaneous coronary intervention, has proved to be beneficial beyond the confines of the cardiac catheterization laboratory. The glycoprotein IIb/IIIa inhibitor has inspired much research in the past few years of its use in the management of acute coronary syndromes. The CAPTURE, PURSUIT, PRISM, and PRISM-PLUS trials have all documented the beneficial effects of glycoprotein IIb/IIIa inhibition that have reduced 2 of the major sequelae of acute coronary syndromes: myocardial infarction and death. Through the implementation of primary research-based data, it is the job of practitioners to appropriately stratify and implement judicious use of glycoprotein IIb/IIIa inhibition with the population affected by acute coronary syndromes.