Pathophysiology of Acute Coronary Syndrome - Essay Example

Acute Coronary Syndrome: A review of the Literature of the Nursing of the June 24, Acute Coronary Syndrome Introduction Acute coronary syndrome (ACS) is the acute presentation of coronary artery disease (CAD) which is manifested as unstable angina (UA), ST segment elevation myocardial infarction (STEMI) or non- ST segment elevation myocardial infarction (NSTEMI) (Noble, 2011). Nearly 1.5 million people are hospitalized with ACS annually, out of which more than two-thirds suffer from UA and NSTEMI (Lloyd-Jones et al. 2009). Globally, ACS is a leading cause of death in pre hospital setting as well as in hospitalized patients. Thus, it is imperative that identification of patients with ACS is quick and accurate, risk stratification is done and management is commenced as early as possible to achieve good outcomes in the short and long turn (Housholder-Hughes, 2011). The role of nurses in the management of ACS is crucial in all aspects, be it diagnosis and assessment, triage, pharmacotherapy, perioperative management, critical care, postoperative care, discharge and rehabilitation. All nurses should have evidence based knowledge so that they can make informed decisions in the management of an ACS patient. This review aims to describe the pathophysiology, nursing diagnoses and assessment, and nursing interventions of acute coronary syndrome. Current research and articles relevant to the aforementioned topics were reviewed and analyzed in order to provide a base for evidence based practice. The literature was retrieved by performing a MEDLINE and Google/Google Scholar search on the internet combined with a manual search for journals and books pertaining to the above mentioned topics. The keywords and their combinations that were used were acute coronary syndrome, nurse, nurse practitioner, ACS, pathophysiology, diagnosis, pharmacotherapy, unstable angina, STEMI, NSTEMI, myocardial infarction, MI, management, nursing assessment, and nursing interventions. Although, the articles identifying assessment, interventions, and their impact on the management of ACS specifically in the context of nursing are few, the guidelines targeting healthcare practitioners in general have been adapted for nurses by most authors in their recommendations. Pathophysiology of ACS According to Hansson (2005), deposition of atherosclerotic plaques in walls and lumens of arteries (atherosclerosis) is an inflammatory process resulting from an interaction of immune and metabolic risk factors. Acute coronary syndromes occur when reduced blood flow causes sudden myocardial ischemia. This happens when a thrombus is formed on the surface of the atherosclerotic plaque as a result of plaque rupture or endothelial erosion. Thrombus formation involves platelet activation and adhesion, lipid accumulation, and chemokines and other inflammatory molecules. Aging combined with risk factors such as family history, hypertension, hyperlipidemia, smoking, diabetes and obesity causes as well as accelerates the process of plaque deposition in the walls of arteries (Lloyd-Jones et al., 2009; Noble, 2011). Sudden plaque disruption leads to decreased blood supply to the myocardium which manifests as UA, STEMI and NSTEMI. Coronary spasm also plays a role in causing ACS (Hansson, 2005). STEMI occurs when there is almost complete occlusion of the coronary artery leading to myocardial infarction (MI). It is characterized by persistent ST segment elevation. NSTEMI is associated with MI without ST segment elevation. It is differentiated from UA by assessment of cardiac troponins as they are not elevated in UA but are elevated in MI (Marshall, 2011). Nursing diagnoses and assessment Importance of triage and timely management Various authors have demonstrated that delaying therapy, more than 30 minutes for fibrinolytic therapy and more than 90 minutes for percutaneous coronary intervention (PCI) therapy, from the time of onset can increase morbidity and mortality (Mehta et al., 2009; O’Connor et al., 2010). Unal, Critchley and Capewell (2004), Fox et al (2007) and Knight and Timmis (2011) reported a decreasing trend in mortality from ACS. Arslanian-Engoren et al. (2011) postulated that one of the main reason for this is rapid diagnosis and prompt initiation of therapy. They conducted a descriptive study using a questionnaire asking ED nurses about their compliance with the American College of Cardiology/American Heart Association (ACC/AHA) guidelines. Of the 158 responses they received, none showed a full compliance. Thus, so far as triaging is concerned, nurses play a vital role and they must be made more aware of the fact by utilizing tailored educational interventions as wrongly triaging these patients can have serious consequences (Sen, McNab & Burdess, 2009). Patient Presentation: History and Physical Examination During emergency department (ED) evaluation, diagnosis of ACS can be done by history, physical examination, ECG and cardiac biomarkers (Roebuck & Farrer, 2006). These authors state in their article that the main challenges faced by nurses in ED are differentiating cardiac from non-cardiac causes of pain and endorsing evidence based practice and guidelines. Most common symptom of ACS is chest pain. Nurse should speedily assess the characteristics of pain, associated symptoms, family history and risk factors (NICE, 2010). The main symptoms are chest pain which is retrosternal, more intense and longer lasting than angina, does not resolve with rest and may or may not radiate to other parts of the body; dyspnea, nausea, vomiting and dizziness (O’Connor et al., 2010). Pain relief with nitrates is not reliable to differentiate angina from ACS. As chest pain is the most common symptom reported by patients, nurses should be proficient in the assessment of pain in its entirety (Briggs, 2010). Some patients, especially diabetics may present with ‘silent ischemia’, so the suspicion of ACS should be kept high in these patients (Conway & Fuat, 2007). Physical examination may reveal cold extremities, diaphoresis, hypotension, and chest crackles due to pulmonary edema, or other signs of heart failure. However, it may be normal. Kuhn et al (2011) reviewed triage relevant literature and found that age and gender differences can lead to a bias in the interpretation of ACS symptoms and nursing assessment. Chest pain in female patients or younger adults may not be taken as seriously as in the other ‘high risk’ population and can lead to a delay in the treatment. This bias can be prevented by paying attention and thorough assessment of the patient. Diagnostic Tests Diagnostic tests of most importance are ECG and blood cardiac markers. ECG should be immediately performed, if not already done during transportation. Nurses working in ED or managing acute chest pain patients should be proficient in ECG interpretation. Presence of new ST segment deviation (>1mm), multiple lead T wave inversions or new left bundle branch block are highly suggestive of ACS secondary to CAD (O’Connor et al, 2010). In the non ST segment elevation ACS, cardiac enzymes are useful to distinguish between UA and NSTEMI (Coady, 2006). ECG can be used to localize the site of infarction. Cardiac enzymes, troponins and creatine kinase specific for heart muscle (CK-MB) are raised in myocardial infarction. Troponins are highly sensitive and specific for detection of myocardial damage. They can be detected in the blood within 6 hours and remain elevated for 2-3 weeks (Smeltzer, Bare, Hinkle, & Cheever, 2009). Thus, main nursing diagnoses in a patient with ACS are inadequate perfusion in the coronary tissue, inadequate cardiac output due to heart failure, psychological issues due to anxiety and feeling of ‘impending doom’, and feeling of inability to deal with post event care. Nursing interventions Nursing interventions in the setting of ACS target areas such as emergency department care, cardiac care unit, perioperative management and cardiac rehabilitation. The key interventions are identification and diagnosis of ACS in a patient, treatment administration, emotional and psychological support to patients and their families, discharge care and instructions, and patient guidance and counseling for cardiac rehabilitation. ACC/AHA guidelines (O’Connor et al, 2010) describe the goals that nurses should strive for. These goals are to prevent heart failure and major adverse cardiac events (MACE), and to treat the immediately life threatening complications of ACS. Also, general nursing goals of preventing further damage, optimizing all systems, pain relief, reducing anxiety and post event planning and care are also to be achieved. Nursing interventions Nurses perform the assessment of presenting symptoms and physical examination which includes blood pressure, heart rate, respiratory rate and oxygen saturation measurement, and chest examination. Quick assessment allows establishment of the diagnosis so that management can be promptly initiated. Also, the evolving clinical status of the patient can be compared with the baseline parameters. Vital signs are measured so that the needful can be done. Oxygen is administered at the rate of 4 l/minute through nasal prongs or mask if patient showing saturation less than 94% in order to increase oxygen supply to the ischemic muscle (NICE, 2010). Intravenous access is secured for drugs and fluid administration and blood sample is drawn for cardiac markers, electrolytes and coagulation studies (O’Connor et al, 2010). An ECG is promptly obtained and assessed by the nurse if competent or shown to a physician (Hutton, 2011). Promptly obtaining an ECG helps in the classification of the syndrome and according management. Patient should be put at rest and his comfort should be ensured. Rest ensures that oxygen demand of the heart is not increased. Two IV lines must be secured and carefully maintained. Fluid infusion volume is carefully noted and assessed frequently in view of heart failure, in order not to precipitate pulmonary edema. Urine output is monitored in all patients, especially so, in patients with renal impairment. Left ventricular failure will manifest as hypotension and oliguria. Any deterioration or signs of inadequate perfusion due to heart failure should be reported immediately to the physician ( Smeltzer et al, 2009) . Respiratory and cardiac system should be continually (at least 4 hourly) assessed. Antiplatelet therapy in the form of non-enteric coated aspirin (160-325 mg) and clopidogrel are administered, if not already given during transportation, as platelet activation plays a role in athero-thrombotic events and development of secondary ischemia (Berra, Fletcher & Handberg, 2011). Also, authors have emphasized the importance of counseling and patient education for antiplatelet therapy as a part of nursing interventions (Berra, Fletcher & Handberg, 2011). Nurses should know the contraindications and adverse effects of the drugs that they are administering and aim to prevent their complications by complete assessment of their patients. Morphine is given intravenously to relieve pain and anxiety so that tachycardia due to pain does not lead to further ischemia (NICE). Nitroglycerin, sublingual or spray, is another agent which is administered if no contraindication exists (O’Connor et al, 2010). ‘MONA’ is the mnemonic that is sometimes used to sum up these interventions, wherein, M stands for morphine, O stands for oxygen, N stands for nitroglycerine and A which is used for aspirin. If patient needs reperfusion for STEMI, relevant preparation is done. This preparation includes consent from patient and family, notification and transfer to the cardiac catheterization facility, fibrinolytic checklist and initiation of fibrinolytic therapy. Continuous ST segment monitoring is done to recognize ongoing or recurrence of ischemia. Sangkachand, Sarosario and Funk (2011) identified the barriers to ECG monitoring on cardiac monitors in nurses and recommended software to simplify the interpretation. Nurses should also be well versed with latest basic life support and advanced life support guidelines, and should actively participate in the resuscitation of the patient with chest compressions, using defibrillator or arrhythmia management if cardiac arrest occurs. Nurses use their communication skills to provide information to the patient and attendants at various stages and alleviate their anxiety (Marshall, 2011). They are the best suited health care personnel for this purpose as they spend maximum time caring for the patient and interaction at a more personal level is a part of the nursing training. STEMI Reperfusion of the occluded coronary artery is the goal of treatment in STEMI. PCI and fibrinolytic therapy are the two reperfusion strategies currently available, each with their advantages and disadvantages (Peacock, Hollander, Smalling & Bresler, 2007). Recent evidence has again proven that PCI performed expeditiously is the treatment of choice for reperfusion in STEMI (Knight & Timmis, 2011). Fibrinolytic treatment is an option if PCI is unavailable. O’Connor et al (2010) recommend that if less than 12 hours have elapsed from the onset of symptoms, reperfusion therapy is started with a goal of 90 minutes for door-to-balloon inflation (PCI) and 30 minutes for door-to-needle for fibrinolysis. Sloman and Williamson (2009) reviewed the evidence associated with thrombolysis in United Kingdom and the literature reviewed revealed that nurses can safely and effectively perform decision making and administer thrombolysis with an improved door to drug time. NSTEMI/ UA American Heart Association, American College of Cardiology and European College of Cradiolgy guidelines (O’Connor et al 2010, Hamm et al, 2011) recommend risk stratification with Thrombolysis in Myocardial Ischemia (TIMI) risk score or Global Registry of Acute Cardiac Events (GRACE) score for NSTEMI/UA patients. In patients with high risk or troponin elevation, early invasive strategy (within 2 hours of presentation) should be considered if hemodynamic instability or heart failure occurs. Adjunctive treatment with nitroglycerin, heparin, beta blockers, clopidogrel, glycoprotein IIa/IIIb inhibitors and anti-thrombin agents is started as per the protocol and defined by the patient. There are certain differences in American and European guidelines regarding administration of antiplatelet drugs such as clopidogrel, prasugrel and ticlopidine, and the guidelines can be followed as per the protocol of the region. Pharmacotherapy Drugs used in the management of ACS are antiplatelet, beta blockers, angiotensin converting enzyme inhibitors and statins (Ramanath & Eagle, 2007). Immediate loading dose of aspirin and clopidogrel followed by maintenance treatment is currently recommended (Knight & Timmis, 2011). Postoperative care and discharge planning Wit, Bos-Schaap, Hautvast, Heestermans & Umans (2011) reported their experience with nurse practitioners who manage post -ACS patients, operative or non-operative. They conclude that a nurse led post ACS units is feasible and effective with a low complication rate and more satisfactory for patients as management is on a more personal level. The intervention performed by these nurse practitioners are participation in clinical rounds and discussions, evaluation of patients, patient and family education and preparation for operation, daily care and discharge advice. The last entails advice about medication, lifestyle and risk factor modification, follow-up and recognition of alarm signs and symptoms. Support is provided for quitting smoking and patients are educated regarding nutritional management. Cossette, D’Aoust, Morin, Heppell, & Fraser-Smith (2009) developed a nursing intervention to increase patients’ enrollment in a cardiac rehabilitation program. In the first two phases, the barriers to cardiac rehabilitation were identified and refined. The 3rd phase of the intervention examining anxiety, risk factor modification, compliance with medication, emergency revisits and illness perception, is going on and results will demonstrate the full effectiveness of the intervention. It is however understood that the guidance given by nurses regarding management of risk factors and secondary prevention significantly helps to prevent the recurrence of ACS. Summary Evidence based management of ACS has many nuances for nursing practice. Apart from the routine nursing care, there are special aspects in the management of ACS such as time management and ECG interpretation. Nursing goals of continual assessment, general nursing care, prevention of secondary damage and psychological support remain the same. To bring in a scientific approach in their nursing practice, the nurses should keep themselves updated on the recent guidelines and modify their practices according to the recent evidence. References Arslanian-Engoren, C., Eagle, K.A., Hagerty, B., & Reits, S. (2011). Emergency department triage nurses’ self-reported adherence with American College of Cardiology/American Heart Association myocardial infarction guidelines. Journal of Cardiovascular Nursing, 26(5), 408-413. Berra, K., Fletcher, B.J., Handberg, E. (2011). Antiplatelet therapy in acute coronary syndromes: implications for nursing practice. Journal of Cardiovascular Nursing, 26(3), 239-249. Briggs, E. (2010). Assessment and expression of pain. 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Nursing role to improve care to infarct patients and patients undergoing heart surgery: 10 years’ experience. Netherlands Heart Journal, 20, 5–11. doi:10.1007/s12471-011-0225-y Read More