Understanding STEMI And Modifiable/Non-modifiable Risk Factors For Myocardial Infarction: An Essay.

STEMI and how it is caused

Question:

Discuss about the Pacific Rim International Journal Of Nursing.

STEMI or ST elevation myocardial infarction is a type of heart attack that is caused due to blockage of blood for a prolonged time to a significant portion of the heart (Heart.org 2018). Acute coronary syndromes are usually differentiated based on the absence or presence of ST elevation on the ECG, and is called Non STEMI and STEMI respectively. Patients suffered from Acute Myocardial Infarction require immediate therapy without delay with percutaneous coronary intervention PPCI done within 90 minutes of first medical contact (Camaro & de Boer 2015, p. 243).

The term ‘risk factor’ was coined by the researchers of Framingham Heart Study, USA for cardiovascular diseases (CVD). The studies showed factors like high blood cholesterol, smoking, hypertension, ECG abnormalities can increase the risk for CVD. The risk factors can be divided into modifiable and non modifiable risks (metalyse.com 2018).

Several modifiable risk factors are associated with Myocardial Infarction, like: smoking, abnormal blood lipids, diabetes, hypertension, abdominal obesity, inadequate physical activity, psychosocial factors, inadequate consumption of fibre, alcohol consumption.

Smoking is considered as a significant risk for myocardial infarction. Studies show that the risk of cardiac arrest can increase directly proportionally to the number of cigarettes smoked without any upper limit. Smoking or inhaling products other than cigarettes can also increase risks for myocardial infarction, although not as much as cigarettes (Aygül et al. 2008, p. 4). Studies by Aygül et al. (2009, p 5) supports this data, showing that smoking was found to be more prevalent among STEMI patients. This suggests that the smoking habit of the patient might be related to the condition.

Studies show that regular exercise in moderate to intense levels can reduce the risk of myocardial infaction. Though regular exercise, the normal functioning of the cardiovascular system can be maintained. It also improves respiration and, cardiac output as well as maintains an efficient heart rate and stroke volume and therefore prevents the onset of cardiovascular diseases (Agarwal 2018, p. 541). The patient admitted that he does very little exercise, and works as a computer programmer (which possibly keeps him restricted to his work desk for prolonged periods of time). This can also explain the onset of STEMI in the patient.

Other modifiable risk factors like hypertension, obesity, diabetes, abnormal blood lipids have not been reported for the patient, however it is important to check his dietary intake as well as any signs of psychosocial factors like depression, stress and adverse life effects. Studies have linked cardiovascular disease with psychosocial stressors and poor diet (Lagraauw et al. 2015, p. 19; Reedy et al. 2014, p. 882)

Non modifiable risks includes: age, gender, genetic factors, racial and ethnic background. Studies by Dhingra and Vasan (2012, p. 88) shows that age is an independent risk factor for CVD and can increase by the presence of other risk factors. The risk of CVD increases significantly after the age of 65. Also, the propensity of CVD earlier in life is more probable for males than in females. A family history of CVD in a first degree relative can also increase risks for cardiovascular problems. The patient is 55 years of age, which places him closer to the non modifiable risk for CVD, as well as his gender. Any family history of CVD should be investigated.

Modifiable Risk Factors

Intervention strategies for the patient should include: immediate cessation of smoking, including daily- regular to vigorous exercise, including fibre in diet and restricting the intake of fats. The patient can be referred to a diet consultant as well as an occupational therapist and lifestyle modification support. He also might need regular follow-up with general physician to monitor his cardiac activity.

STEMI is caused due to a complete and persistence blockage of the coronary artery (the vessel that supplies blood to the muscles of the heart) by the formation of a blood clot (thrombus). This blockage leads to damage to the cardiac muscles (and is called a myocardial damage), and the damage increases with the length of time of the blockage, due to increasing damaged muscles of the heart. In animal models, the myocardial injury due to a blockage of the coronary artery spreads in the form of waves, starting from the inner layers of the cardiac muscles to the outer layers, and during infarction, the full thickness of the cardiac muscles are affected. Among patients who have survived STEMI, the infracted or damaged muscle is gradually replaced with a scar tissue (by a process called fibrosis), and the damage is determined by the stroke volume and efficiency of the heart (Ncbi.nlm.nih.gov 2018).

Non-STEMI or NSTEMI is caused by an imbalance between the myocardial demand and supply of oxygen. This is caused due to a lowered blood flow through the coronary vessels. This can be caused by a partial or non-occlusive blood clot (or thrombus) that forms in a disrupted plaque. The clot causes a near complete blockage of coronary artery. Different sequence of events can lead to NSTEMI like: rupture of a plaque with superimposed blood clot which is non-occlusive causing vascular obstruction; dynamic obstruction of cardiac vessels; narrowing of the arteries (reducing the flow of blood); inflammatory reaction; conditions (like hypoxemia, hypotension and hypovolemia) that can cause lowering of blood flow through the coronary vessels. The most common cause of NSTEMI is the rupture of a plaque, causing a blood clot, which prevents or reduces the flow of blood. The rupture usually occurs near the shoulder region and contains a large number of inflammatory cells. The lack of ST elevation in NSTEMI is because the entire thickness of the cardiac walls is not involved, unlike in the case of STEMI (Montalescot et al. 2007, p. 1410). Abnormalities in ECG therefore are not observed in case of NSTEMI, or might only have subtle changes (Ncbi.nlm.nih.gov 2018). Studies by Montalescot et al. (2007, p 1416) shows that both STEMI and NSTEMI has similar prognosis.

During an episode of heart attack, a sharp radiating pain shooting to the shoulder and left arm is caused due to a confusion of the nervous system. The palpation on the left side of the chest is because the anatomical position of the heart slightly tilted to the left. During an episode of heart attack, the nerves that supply the heart and left arm are confused (as signals from the cardiac neurons are felt to originate also from the left arm), since they arise from the same spinal segment. This confusion leads to the sensation of pain to be felt in the left arm, and is also known as referred pain (Banharak  et al. 2018, p. 19; Mata et al. 2014, p. 377). The pain is caused when nervous signals from the cardiac muscles enter the spinal nerve which it shares from the sensory nerve from the left hand. Therefore the sensation of pain travelling from the cardiac nerve is felt in the arm, even though the signal did not originate there.

Non-modifiable Risk Factors

Pallor is referred to as the pale coloration of the skin that can be caused due to an illness, stress, shock, and anaemia. This can be caused due to a reduction in the amount of oxyhemoglobin (oxygenated haemoglobin) and increase in the amount of carbamino haemoglobin (haemoglobin bound to carbon dioxide) in the skin and mucous membrane. Oxyhemoglobin is oxygen bound haemoglobin in blood, which has a bright red colour, while carbaminohemoglobin is dull in colour. A rise in the concentration of carbamino haemoglobin in the blood causes the discoloration of the skin. Pallor generally prominent in the face and palms. This is also caused to the reduced blood flow to the peripheral parts of the body. The sites where pallor can be observed are: lower conjunctiva, tip and dorsum of tongue, soft palate, nail beds, palmar or plantar creases, and skin. Pallor can also be caused due to anaemia, or reduction in the haemoglobin concentration in the blood.

Clamminess refers to a cold, most and sticky condition of the skin. This occurs when the temperature of the kin goes below normal and is associated with moisture. The skin also looks pale, and can occur due to cardiovascular problems or a decrease in the flow of blood through the peripheral organs like skin or appendages in order to conserve blood supply to the internal organs. Blockage of cardiac vessels can also lead to clamminess, as the body tries to restrict the blood to the skin and peripheral organs. During STEMI, the flow of blood to the coronary artery decreases, this leads to a condition of shock. The reduction of the flow of blood to the skin results in the drop in the skin temperature, as well as the blood pressure, which causes shock. Increase in the vascular resistance of peripheral organs also can cause reduction in the blood supply thereby leading to clamminess (Williams and Wilkins 2018).

Nursing Care plan for STEMI requires two types of data: subjective data and objective data. The subjective data consists of information from the patient, and include factors like chest pain, feeling a sense of pressure on the chest, PQRST pain assessment (provoke/precipitate/palliate, quality, radiate, severity of symptoms, time). Objective data can include clinical findings such as: ST elevation in ECG report, decreased oxygenation of blood, left ventricular failure and tachycardia.

The care plan for STEMI should focus on the following factors: providing relief from pain and ischemic signs or symptoms; preventing myocardial damage; eliminating respiratory dysfunction; establish and maintain adequate blood flow to the tissues, alleviating anxiety; detecting complications early or preventing them; controlling or removing chest pain, restoring heart rate and blood circulation to adequate levels; adequate activity level to enable basic self care is achieved; proper understanding of the disease, treatment plan and prognosis is achieved. The priorities of care should be highest for ensuring relief from pain and anxiety, followed by reduction in the myocardial stress and workload. The next priorities should include the prevention or detection of fatal dysrhythmias, assisting and treating complications caused due to it and promotion of cardiac health and self care (Nice.org.uk 2018).

Intervention Strategies for Patients

As a part of intervention, the nurses can administer oxygen and medications to reduce symptoms; encourage bed rest, providing back rest for the patient to reduce discomfort of the chest. The patient should also be encouraged to frequently change positions to prevent accumulation of fluids in the base of lungs. Skin temperature and peripheral pulse should be regularly checked to identify signs of palliation or clamminess and to monitor flow of blood. Cardiac rhythm, rate, heart sounds, blood pressure, chest pain, respiratory systems, urinary output, skin colour change and clinical reports should be monitored regularly (Nice.org.uk 2018).

Different types of treatment/management can be applicable for the treatment of STEMI, which are discussed below:

1. Morphine Oxygen Nitro-glycerine Aspirin (MONA). Aspirin is used to dilute or thinning the blood. A total of 324mg of Aspirin can be administered for this process. Nitro-glycerine can be administered with Aspirin to dialate the blood vessels and remove obstruction and blockage of blood. 0.4mg tablet of nitro-glycerine can be administered sublingually to alleviate chest pain. A second dosage can be administered after 5 minutes if the pain does not subside. The blood pressure of the patient should also be monitored and the systolic pressure should be below 90 mm of Hg. Oxygen is given if the oxygenation of blood is below 94% or if the patient feels out of breath. 2 L of NC can be administered initially. However, caution must be applied while administering oxygen as it can cause vasoconstriction, reducing the flow of blood even further. Morphine is administered if the chest pain is not alleviated by aspirin and nitro-glycerine.
2. 3 or 5 Lead Monitoring: The patient needs to be placed on cardiac monitoring immediately to identify worsening of condition.
3. Cardiac Catheterization with Percutaneous Coronary Intervention (PCI): In the catheterization lab, the blood clot can be located, and a stent can be placed to regain the blood flow to the heart.
4. Heparin: This is an anticoagulant, and dissolves blood clot that blocks the vessels. For STEMI, heparin should be administered at 60 units per kg (up to a maximum of 4,000 units) for bolus and 12 units per kg for continuous infusion.
5. Monitoring Cardiac Enzymes (Troponin I, Creatinin Kinase MB): Elevated levels of these enzymes are generally the indicators of stress or injury to the cardiac muscles. Troponin enzyme plays an important role in the interaction between the myosin and actin filaments of the cardiac muscle. Destruction of the cells (due to stress or injury) leads to the release of the enzymes in the surrounding area. Creatinine Kinase in the cardiac muscle cells converts ATP to ADP, thereby releasing energy for the contraction of the heart muscles. Damage to the cardiac cells causes the enzyme released into the blood stream (nurselabs.com 2018)

The results of the intervention can be evaluated by an absence of pain or ischemic signs and symptoms, prevention of myocardial damage, absence of respiratory dysfunction, adequate blood flow to tissues restored and reduction in anxiety levels.

For discharge and home care, the patient should also be educated about healthy lifestyle. Support should also be provided by home care nurses for following up with the patients progress, supporting ongoing treatment and ensure adherence to dietary restrictions and lifestyle changes.

Roper-Logan-Tierney Model for Nursing is a nursing care theory that is based on the activities of daily living. The model is used as a tool for assessment of changes caused in the patient due to illness. The model helps to understand what independent living means, and helps to identify activities that are important to maintain independent living, with which the patient might be facing difficulty. This can help the nurse to determine the intervention strategies that can allow the patient to regain independence or reduce any dependencies the patient might be facing. The activities of daily living can e used as a cognitive approach to assess care for the patient and organize them appropriately. The 12 activities which effects the quality of life, outlined in the model includes: maintenance of a safe environment; communication; breathing; eating and drinking; elimination; washing and dressing; controlling temperature; mobilization; working and playing; expressing sexuality; sleeping and death or dying. The model also considered the factors that can influence activities of living as biological, psychological, sociocultural, environmental, politicoeconomic factors.

The ability to perform acts of daily living can be used as a method to assess the functionality of a person. Based on this ADL can be classified into basic ADL (that includes self care activities like eating, drinking, dressing and bathing) and instrumental (like housekeeping, transportation or managing medications).

Monitoring the breathing of the patient is an important care strategy, since it allows identification of any breathing difficulties or abnormalities which can underline any complication. Using pulse oxymetry machine can help to measure the levels of blood oxygen saturation, and help to identify when oxygen therapy might be required. Mobility can help to improve body function as well as recovery. As per NICE guidelines, increasing mobility can reduce the risk of deep vein blood clots called thromboembolism. Communication is important to develop therapeutic relationship with the patient. This can allow the nurse to bond with the patient, and able to understand their feelings and anxieties. Personal Cleansing and dressing also is an important for patients as it helps in faster recovery and prevent infections. Studies by Dunlay et al. (2015, p. 266) shows that heart failure, diabetes, peripheral vascular dysfunctions and cerebrovascular disease can adversely affect the mobility or self care ability of the patient. The decrease in mobility and an inability or reduced ability to perform self care activities are also related to a reduced quality of life and increased risks of hospitalization and even death (Dunlay et al. 2015, p. 266).

The difference between STEMI and NSTEMI

Maintaining acts of daily living can require assistance in deferent aspects such as: providing companionship and mental support, transportation, preparation of meals, managing household, and managing medications, communicating with others and managing finances.

References:

Agarwal, S., 2012. Cardiovascular benefits of exercise. International Journal of General Medicine, pp.541.

Aygül, N., Özdemir, K., Abac, A., Aygül, M., Düzenli, M., Vatankulu, M., Yaz, H., Özdo, I. & Karakaya, E., 2008. Prevalence of risk factors of ST segment elevation myocardial infarction in Turkish patients living in Central Anatolia. Viewed 8 Mar. 2018, <https://www.journalagent.com/anatoljcardiol/pdfs/AnatolJCardiol_9_1_3_8.pdf>.

Aygül, N., Ozdemir, K., Abaci, A., Duzenli, M., Yazici, H., Ozdogru, I. & Karakaya, E., 2009. Prevalence of risk factors of ST segment elevation myocardial infarction in Turkish patients living in Central Anatolia. - PubMed - NCBI. Anadolu Kardiyol Derg. Vol. 9. No. 1, pp. 3-8. Viewed 8 Mar. 2018, < https://www.ncbi.nlm.nih.gov/pubmed/19196566>.

Banharak, S., Zahrli, T. & Matsuo, H., 2018. Public Knowledge about Risk Factors, Symptoms, and First Decision-making in Response to Symptoms of Heart Attack among Lay People. Pacific Rim International Journal of Nursing Research, vol. 22, no. 1, pp.18-29.

Camaro, C. & de Boer, M.J., 2015. STEMI or non-STEMI: that is the question. Netherlands Heart Journal, Vol. 23, no. 4, pp.243-244. DOI: 10.1007/s12471-015-0665-x

Dhingra, R. & Vasan, R., 2012. Age As a Risk Factor. Medical Clinics of North America, Vol. 96, no. 1, pp.87-91.

Dunlay, S., Manemann, S., Chamberlain, A., Cheville, A., Jiang, R., Weston, S. & Roger, V., 2015. Activities of Daily Living and Outcomes in Heart Failure. Circulation: Heart Failure, Vol. 8, No. 2, pp.261-267.

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Lagraauw, H.M., Kuiper, J. & Bot, I., 2015. Acute and chronic psychological stress as risk factors for cardiovascular disease: Insights gained from epidemiological, clinical and experimental studies. Brain, behavior, and immunity, Vol. 50, pp.18-30.

Mata, J., Frank, R. & Gigerenzer, G., 2014. Symptom recognition of heart attack and stroke in nine European countries: a representative survey. Health expectations, Vol. 17, No. 3, pp.376-387.

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Montalescot, G., Dallongeville, J., Van Belle, E., Rouanet, S., Baulac, C., Degrandsart, A. & Vicaut, E., 2007. STEMI and NSTEMI: are they so different? 1 year outcomes in acute myocardial infarction as defined by the ESC/ACC definition (the OPERA registry). European heart journal, Vol. 28, No. 12, pp.1409-1417.

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Reedy, J., Krebs-Smith, S.M., Miller, P.E., Liese, A.D., Kahle, L.L., Park, Y. & Subar, A.F., 2014. Higher Diet Quality Is Associated with Decreased Risk of All-Cause, Cardiovascular Disease, and Cancer Mortality among Older Adults1, 2. The Journal of nutrition, Vol. 144, No. 6, pp.881-889.

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