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RUNNING HEAD: MYOCARDIAL INFARCTION1 A CASE STUDY OF MYOCARDIAL INFARCTION Students Name Course Title Institutional affiliation
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MYOCARDIAL INFARCTION2 Student Case Study Student Name: Patient Physical Details and Vitals Gender:MaleAge:56Body Weight (Kg): 96Height (M): 1.53 Heart Rate:105BP:155/92Temperature(C0):37.1Resp. Rate:26/min Patient Clinical Details Main Complaint/ Symptoms: Prolonged, central, crushing chest pain radiating to the neck and shortness of breath. Physical Exam Results: General appearance- patient appeared lethargic, and in pain. He was diaphoretic. Respiratory – dyspnoea at rest, Cardiovascular – chest pain, high pulse rate, and elevated blood pressure Gastrointestinal – no significant findings Central nervous system- normal cranial nerves functions. Musculoskeletal – no significant findings Review of Systems/Relevant History: Nausea and light-headedness He is a diagnosed hypertensive patient on medication He is recognized obese with a BMI of 38. He uses alcohol occasionally at 6 units per week and has 10 pack-years of smoking, however, quit three years ago due to the diagnosis of hypertension. A Family history of sudden death as father died at 63 with a suspected cardiac event. Mother is a known diabetic. Diagnostic Samples and Imaging Blood Faeces Urine Sputum Swab  Fluids Tissue Cytology Other, namely:Chest radiograph Tests / Profiles Requested BiochemistryHematologyMicrobiologyHistology/Cytology Urea and electrolytes Creatinine kinase 12hr troponin T and I Blood glucose Total cholesterol Full blood count Urgency:NormalSample taken from patient: URGENTDate:(dd/mm/yyyy) Time:(hh/mm) FastingNon-fasting
MYOCARDIAL INFARCTION3 Other Relevant Clinical Information Drug therapy:Amlodipine Atorvastatin Last dose:5mg QD 40mg QD Date:(dd/mm/yyyy) Time:(hh/mm) Other relevant clinical information: No food or drug allergies No history of past surgical procedures Notable Initial Test Results (and Reference Range) Bun (8 -21 mg/dl)- -----------------------------------------------------17 mg/dL Haematocrit (40 -52%)------------------------------------------------ 45% Haemoglobin (13 -17 g/dL) ------------------------------------------ 15 g/dL Blood Sugar (4- 10 mmol/L) ----------------------------------------- 5.2 mg/Dl Total Cholesterol (<4 mmol/L) -------------------------------------- 6.0 mmol/L Electrolytes Potassium (3.5 – 5 mmol/L) -------------------------------- 4.4 mmol/L Sodium (135-145 mmol/L) --------------------------------- 133 mmol/L Serum Troponin I (< 1.5 ng/ml) -------------------------------------- 66.6 ng/ml Serum Creatinine Kinase (0-200 IU/L) ------------------------------ 1494 IU/L Serum Creatinine Kinase MB (CK-MB) (< 7 IU/L) --------------- 33.9 IU/L Further Testing Details (if required) 12 Lead ECG was done. Further Testing Results (if required) ECG showed sinus tachycardia with ST wave elevation of 3mm in the inferior leads and features of left bundle branch block. Pathophysiology Mr. Crawford is a 56-year-old male patient who presented with retrosternal chest pain that was prolonged, radiating to the neck and described as crushing in nature. He is a known hypertensive on medication, obese with a BMI of 38 and a former smoker with 10 pack years. His vitals were deranged with a tachycardia of 105 beats per minute, an elevated blood
MYOCARDIAL INFARCTION4 pressure of 155/92 and a respiratory rate of 26 breaths per minute. His weight is 96 Kg and a height of 1.53 meters putting her body mass index at 38 which is obese. He was admitted for the complaints with a suspicion of an acute coronary syndrome. On admission he was given heparin 5000 units stat, reteplase 10 units iv bolus and morphine 2.5 mg iv for the pain and aspirin 300mg on the way to the hospital. A diagnostic workup was started with a 12 lead ECG and cardiac enzymes done. The ECG and biomarkers confirmed an ongoing ST- elevation myocardial infarction (STEMI). The management involved continuous monitoring of vitals and ECG, serial cardiac markers, oxygen therapy by nasal prongs and thrombolytic therapy as a definitive solution is sought. Myocardial infarction is an acute coronary syndrome that occurs due to interruption of blood flow to the heart muscles leading to the death of myocardium otherwise named a heart attack (Kumar, Abbas, Fausto, & Aster, 2014). This blockage is in part due to blockage of coronary vessels following rupture of an atherosclerotic plaque in the artery wall that forms an occluding thrombus or an embolic phenomenon. Up to 80% are due to occluding arteriosclerotic plaque with superimposed thrombus (Burke & Virmani, 2007). Pre-existing hypertension and obesity are known risk factors for cardiovascular disorders (Thune et al., 2008). Mr. Crawford is a known hypertensive and obese. Atherosclerotic plaques are depositions of lipid within artery wall with surrounding fibroblast proliferation and a fibrous cap (Nabel & Braunwald, 2012The pre-existing plaque acts as a nidus for thrombus formation leading to infarction of the downstream myocardium supplied by that coronary branch (Frangogiannis, 2015). Plaque rupture activates platelet aggregation and activation of coagulation cascade due to exposure of tissue factor (Kumar, Abbas, Fausto, & Aster, 2014). This is the rationale
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MYOCARDIAL INFARCTION5 of early antithrombosis and anticoagulation in the setting of MI as seen in the management of Mr. Crawford by the provision of aspirin, heparin, and reteplase. The clinical presentation follows the biochemical, functional and morphological changes following ischemia of the myocardium (Kumar, Abbas, Fausto, & Aster, 2014). Due to occlusion, the myocardium stops aerobic glycolysis leading to reduced ATP and accumulation of metabolic waste in the cells (Kumar, Abbas, Fausto, & Aster, 2014). There is a rapid loss of contractility in the affected myocardium and if the injury continues this becomes irreversible (Frangogiannis, 2015). This is the rationale of dropping blood pressure in the setting of MI, a phenomenon termed cardiogenic shock. However, the blood pressure could also be elevated due to the release of compensatory sympathetic discharge and elevated levels of catecholamines (Kumar, Abbas, Fausto, & Aster, 2014). This also leads to tachycardia and nausea involved in MI. Mr. Crawford’s blood pressure was elevated at 155/92. The ischemic changes cause arrhythmias and myocardial irritability. The cardiac biomarkers are enzymes released by dying myocytes and are good predictors of myocardial infarction (Thygesen et al., 2012) They start rising minutes after the event and some remain elevated for days. They include troponin T and I, myoglobulin, creatinine kinase and creatinine kinase MB (CKMB). They were all elevated in Mr. Crawford’s case. Metabolic changes are linked to intracellular changes stemming from depletion of ATP stores, inability to regulate electrolyte pumps. This leads to sodium, potassium and calcium derangements. Potassium and calcium imbalance is implicated as one of the causes of ventricular arrhythmias seen in MI. Mr. Crawford had elevated potassium and hyponatremia.
MYOCARDIAL INFARCTION6 The etiology of chest pain in myocardium ischemia is poorly understood but has been hypothesized to be due to the release of chemical mediators triggered by ischemic changes within the myocardium cells (Leach & Fisher, 2013). Circulatory derangements are however due to ventricular dysfunction caused by loss of myocardium (Walker & Colledge, 2013). Infarction of myocardium heals by scar formation leading to permanent loss of contractility in that area. If the dysfunction is systolic, cardiac output drops leading to a fall in blood pressure and coronary perfusion (Walker & Colledge, 2013). This has the disadvantage of potentiating the ischemia. A diastolic dysfunction will lead to increased left ventricular diastolic pressure that causes back pressure to the lungs that manifest as pulmonary congestion (Walker & Colledge, 2013). This leads to hypoxemia and difficulty breathing, impaired oxygen transport and further ischemia. A chest radiograph was requested for Mr. Crawford to access pulmonary congestion and also the cardiac profile.
MYOCARDIAL INFARCTION7 References Burke, A. P., & Virmani, R. (2007). Pathophysiology of Acute Myocardial Infarction. Medical Clinics of North America, 91(4), 553-572. doi:https://doi.org/10.1016/j.mcna.2007.03.005 Frangogiannis, N. G. (2015). Pathophysiology of Myocardial Infarction.Compr Physiol, 5(4), 1841-1875. Kumar, V., Abbas, A. K., Fausto, N., & Aster, J. C. (2014).Robbins and Cotran pathologic basis of disease, professional edition. London: Elsevier health sciences. Leach, A., & Fisher, M. (2013). Myocardial ischaemia and cardiac pain – a mysterious relationship.British Journal of Pain,7(1), 23–30. http://doi.org/10.1177/2049463712474648 Nabel, E. G., & Braunwald, E. (2012). A tale of coronary artery disease and myocardial infarction.New England Journal of Medicine,366(1), 54-63. Thune, J. J., Signorovitch, J., Kober, L., Velazquez, E. J., McMurray, J. J., Califf, R. M., ... & Pfeffer, M. A. (2008). Effect of antecedent hypertension and follow-up blood pressure on outcomes after high-risk myocardial infarction.Hypertension,51(1), 48-54. Thygesen, K., Alpert, J. S., Jaffe, A. S., Simoons, M. L., Chaitman, B. R., White, H. D., ... & White, H. D. (2012). Third universal definition of myocardial infarction.European heart journal,33(20), 2551-2567. Walker, B. R., & Colledge, N. R. (2013).Davidson's Principles and Practice of Medicine E- Book. Elsevier Health Sciences.