Heart Attack: Acute Myocardial Infarction
Acute myocardial infarction is commonly known as heart attack. It happens when blood flowing through one or more coronary arteries is blocked. Coronary arteries are the special type of arteries that supply oxygen and nutrients to the heart. When these arteries are blocked, this stops the oxygen supply to the different parts of the heart. The parts of the heart that do not receive sufficient oxygen become weaker and this leads to heart attack. The ECG of the patient shows abnormal rytham.
Causes of Heart failure
What are the causes of Heart failure?
- Atherosclerosis- It is a disease in which plaque (a fat globule) is formed inside the coronary artery that block the passage of blood flowing through it. Due to the blockage of blood in coronary artery, the heart will not get enough oxygen and nutrients for its functioning and this leads to heart attack.
- Thrombus/Blood clot Formation- Blood can clot by different proteins proteins present in the blood such as fibrinogen that helps in blood clotting. Disturbance in these proteins can cause abnormal blood clot formation. The formation of that type of blood clot in coronary artery causes heart attack.
- Coronary artery Spasm- Sometimes the coronary arteries become contracted and closed and this leads to the hindrance to the blood flowing through that coronary artery. Stopping of blood flow for a long period of time causes heart attack.
What are the common signs of the Heart Attack?
- Shortness of breath
- Upper body discomfort
- Chest discomfort
- Sweating
- Nausea
- Light headedness
- Pain or discomfort spread to chest, neck, jaws, shoulders, both arms, and back
- Trouble in breathing in patients with diabetes
What are the Symptoms of Heart Attack?
- There is a crushing substernal chest pain that is constricting sensation with frequent radiation to the left arm.
- The discomfort or pain is of longer duration (usually >20 minutes). This pain will not be relieved with rest or nitroglycerin.
- If the pain is sudden and it radiates to back then aortic dissection should be considered.
Classification of Myocardial Infarction or Heart Attack
- Type 1- It is spontaneous MI related to ischemia from a coronary plaque rupture.
- Type 2- It is a heart attack due to ischemia resulting from increased oxygen demand or decreased supply.
- Type 3- There is a sudden cardiac death with symptoms of ischemia and new ST elevation.
- Type 4a- Myocardial infarction related to PCI.
- Type 4b- Myocardial infarction associated with stent thrombosis.
- Type 5- Myocardial infarction associated with CABG.
How to diagnose Heart Attack?
In any patient with a history of chest pain is suspected to be of cardiac origin. An ECG should be obtained within 10 minutes of presentation. During evaluation period, physical examination should be performed. If the patient’s history is compatible with cardiac ischemia and the ECG does not meet the criteria then the patient may have unstable angina.
Differential Diagnosis
- Pericarditis– In this, chest pain is worse when the patient is supine and it improves when the patient is sitting upright or slightly forward.
- Myocarditis– The symptoms and the electrocardiographic findings of myocarditis is similar to that of acute myocardial infarction.
- Acute aortic dissection– It includes sharp, tearing chest pain that radiates through the chest in the back.
- Pulmomnary embolism– It includes shortness of breath that is associated with pleuric chest pain, but without any evidence pulmonary edema it suggests pulmonary embolism.
- Esophageal disorders– Esophageal motility disorders and esophageal hyperalgesia causes chest pain that is similar to cardiac ischemic pain.
- Acute cholecystitis– It includes tenderness in the right upper quadrant, fever, and an elevation of leukocyte count favor cholecytsitis. This is diagnosed by hepatobilaiary iminodiaccetic acid (HIDA) scanning.
Laboratory Findings
- Troponin T and Troponin I assay are helpful in diagnosing myocardial infarction.
- Appreciable rise in Creatine Kinase (CK) levels for 4-6 hours are helpful in determining the heart disease.
- Damaged cardiac myocytes releases myoglobin rapidly into blood stream and hence rise in myoglobin level can help in diagnosing the MI.
- Electrocardiography is important diagnostic technique.
- Ecocardiography is also important for diagnosing the MI.
How to treat Myocardial Infarction/ Heart Attack?
- Administration of Aspirin to all the patients with acute myocardial infarction unless by knowing the true history of aspirin allergy.
- Use of supplement oxygen by means of nasal cannula is given to the patients with MI.
- Nitroglycerin (0.4 mg) a sublingual given to the patients to determine whether the ST elevation represents coronary artery spasm.
- Platelet P2Y12 receptor antagonists should be used regularly in all patients with STEMI.
- Reperfusion therapy is performed to treat MI.
