What is myocardial infarction in medical terms
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Understanding Myocardial Infarction in Medical Terms
Definition and Pathophysiology of Myocardial Infarction
Myocardial infarction (MI), commonly known as a heart attack, is defined as the sudden ischemic death of myocardial tissue. This condition typically arises from the thrombotic occlusion of a coronary vessel, often due to the rupture of a vulnerable plaque within the artery. The resulting ischemia leads to significant metabolic and ionic disturbances in the affected myocardium, causing a rapid decline in systolic function. Prolonged ischemia triggers a "wavefront" of cardiomyocyte death, extending from the subendocardium to the subepicardium, and involves mitochondrial alterations that contribute to apoptosis and necrosis of heart cells.
Clinical and Diagnostic Criteria
The diagnosis of myocardial infarction involves several clinical, electrocardiographic, biochemical, and imaging criteria. The universal definition of MI includes the detection of myocardial injury through abnormal cardiac biomarkers, particularly cardiac troponins, in the context of acute clinical myocardial ischemia. This is characterized by a rise and/or fall of cardiac biomarkers with at least one value above the 99th percentile of the upper reference limit, along with evidence of ischemia such as symptoms, ECG changes, or imaging evidence of new loss of viable myocardium .
Epidemiology and Implications
Myocardial infarction is a major cause of death and disability worldwide. It can be a minor event in a chronic disease or a catastrophic event leading to sudden death or severe hemodynamic deterioration. MI may be the first manifestation of coronary artery disease or occur repeatedly in patients with established disease. The incidence of MI in a population serves as a proxy for the prevalence of coronary artery disease, highlighting its significant epidemiological and societal impact .
Symptoms and Immediate Treatment
Symptoms of myocardial infarction include chest pain radiating to the left arm or neck, shortness of breath, sweating, nausea, vomiting, abnormal heart rhythms, anxiety, fatigue, and weakness. Immediate treatment involves administering aspirin to prevent blood clotting, nitroglycerin for chest pain, and oxygen therapy. Early intervention with thrombolytic or clot-dissolving drugs, such as tissue plasminogen activator, streptokinase, or urokinase, within three hours of onset is crucial.
Long-term Management and Prevention
Long-term management of MI includes the use of painkillers like morphine, antihypertensive drugs such as beta-blockers, ACE inhibitors, or calcium channel blockers to lower blood pressure and improve oxygen demand of the heart. Diagnostic tools like ECG, coronary angiography, and X-rays are used to observe coronary artery narrowing. Preventive measures involve lifestyle changes such as a healthy diet, regular exercise, and monitoring of blood pressure to reduce the risk of future events.
Conclusion
Myocardial infarction is a critical medical condition with significant implications for individual health and public health systems. Understanding its pathophysiology, diagnostic criteria, and treatment options is essential for effective management and prevention. Advances in diagnostic techniques and therapeutic interventions continue to improve outcomes for patients with MI, but ongoing efforts in prevention and timely treatment remain paramount.
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