Questions and Answers
What is the underlying pathology of Acute Coronary Syndromes (ACS)?
What is the clinical event responsible for triggering ACS?
What is the cardinal sign of ACS?
What is the purpose of evaluating pre-test probability in ACS?
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What is the location where plaque grows in the coronary arteries?
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What is the consequence of plaque rupture in the coronary arteries?
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What is the primary goal of reperfusion therapy in ACS?
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What is the significance of reciprocal changes in the opposite leads on a 12-lead ECG?
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Which of the following is NOT a symptom of ACS?
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What is the contents of the plaque in the coronary arteries?
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What is the purpose of serial 12-lead ECGs in patients with suspected ACS?
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What is a sign of ischemia or infarction on a 12-lead ECG?
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What is a goal of initial management in patients with ACS?
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How many anatomically contiguous leads must show ST segment elevation to diagnose acute STEMI on a 12-lead ECG?
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What is the primary ECG indicator of acute STEMI?
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What is the characteristic ECG finding in lead AVL for acute inferior STEMI?
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What is the importance of examining the right precordial leads in acute inferior STEMI?
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What is the concern with administering nitroglycerin in right ventricular infarction?
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What is the ECG lead used to identify right ventricular infarction?
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What is the limitation of the STEMI/Non-STEMI paradigm?
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What is the characteristic ECG finding in right ventricular infarction?
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What is the importance of clear communication with hospital staff in patients with acute inferior STEMI?
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What is the ECG finding in isolated posterior STEMI?
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What is the role of paramedics in acute inferior STEMI?
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Study Notes
Acute Coronary Syndromes (ACS)
- ACS is a term used to describe a range of conditions that occur when the blood flow to the heart is blocked, leading to heart muscle damage or death.
- The underlying pathology of ACS is atherosclerosis, a condition in which plaque builds up in the coronary arteries, causing inflammation and damage to the arterial walls.
Atherosclerosis
- Atherosclerosis is a chronic inflammatory response to the accumulation of lipid-rich gruel in the coronary arteries.
- The plaque, or atheroma, grows within the innermost lining of the coronary arteries (tunica intima) and can cause the arterial walls to thicken, leading to a blood clot.
- The contents of the plaque are highly thrombogenic, meaning they can trigger a blood clot if they come into contact with circulating blood.
Plaque Rupture and Blood Clot Formation
- Plaque rupture is the clinical event responsible for triggering ACS.
- When the fibrous cap of the plaque ruptures, the contents come into contact with circulating blood, activating platelets and triggering the clotting cascade.
- The clot can grow and eventually occlude the coronary artery, leading to a heart attack.
Clinical Presentation of ACS
- The cardinal sign of ACS is chest discomfort, which can be poorly localized and described as an uncomfortable sensation, fullness, squeezing, or pressure that lasts more than 15 minutes.
- Other signs and symptoms of ACS include:
- Epigastric pain
- Shortness of breath or difficulty breathing
- Diaphoresis (excessive sweating)
- Nausea or vomiting
- Palpitations or arrhythmias
- Anxiety or feeling of impending doom
Pre-Test Probability
- Pre-test probability refers to the likelihood that a patient has ACS based on their symptoms, medical history, and other factors.
- A high pre-test probability increases the suspicion of ACS and warrants further investigation and treatment.
12-Lead ECG in ACS
- A 12-lead ECG is used to diagnose ACS and identify patients who require immediate reperfusion therapy.
- The ECG can show signs of ischemia or infarction, such as ST segment elevation or depression, T wave inversion, or Q waves.
- The ECG should be interpreted in conjunction with the patient's symptoms and medical history to determine the likelihood of ACS.
Goals of Initial Management
- The goals of initial management are to:
- Restore balance between myocardial oxygen supply and demand
- Relieve pain and anxiety
- Prevent further cardiac damage
- Identify patients who require reperfusion therapy
Reperfusion Therapy
- Reperfusion therapy, such as balloon angioplasty or thrombolytic therapy, is used to restore blood flow to the affected coronary artery.
- The goal of reperfusion therapy is to salvage myocardial tissue and reduce the risk of death and morbidity.
Identifying Acute STEMI on the 12-Lead ECG
- The 12-lead ECG is used to identify signs of acute STEMI, including:
- ST segment elevation in two or more anatomically contiguous leads
- Reciprocal changes in the opposite leads
- T wave inversion or pseudonormalization
- Q waves or significant R wave loss
Serial 12-Lead ECGs
- Serial 12-lead ECGs can help identify patients with ACS who may not have initially presented with diagnostic ECG changes.
- Changing ECG patterns can suggest dynamic myocardial oxygen supply versus demand characteristics, indicating ACS.### ECG Analysis and Acute Inferior STEMI
- Acute inferior STEMI is identified by:
- P waves and QRS complexes in a 1:1 relationship
- Constant PR interval between 120-200 milliseconds
- ST segment elevation in leads 2, 3, and AVF
- Reciprocal change in lead AVL (down-sloping ST segment)
- Importance of lead AVL in diagnosing acute inferior STEMI:
- 99% of the time, a reciprocal change in lead AVL will be present
- The absence of this finding should make you question the diagnosis
- Paramedics' role in acute inferior STEMI:
- Identify the ECG findings and transmit the ECG to the emergency department
- Follow up with a phone call and provide a clinical vignette to activate the cardiac cath lab
Posterior STEMI and Right Precordial Leads
- Posterior STEMI can be identified by:
- Reciprocal changes in the right precordial leads (V1, V2, and V3)
- ST segment depression in the right precordial leads
- Importance of examining the right precordial leads in acute inferior STEMI:
- May identify posterior STEMI
- Train yourself to spot acute isolated posterior STEMI
Right Ventricular Infarction and Nitroglycerin
- Right ventricular infarction may occur with acute inferior STEMI:
- Higher occlusion in the right coronary artery can knock out the right ventricle
- Patients may be preload-dependent and dependent on central venous pressure
- Nitroglycerin administration in right ventricular infarction:
- May drop blood pressure and worsen the condition
- Preload-dependency makes patients more susceptible to hypotension
- Identifying right ventricular infarction:
- Take lead V4R (mirror position on the right side of the patient's chest)
- Look for ST elevation in lead V4R (even a small amount is significant)
Case Study
- 79-year-old female with acute inferior STEMI and suspected right ventricular infarction:
- ECG findings: ST elevation in leads 2, 3, and AVF, reciprocal change in lead AVL
- Right ventricular infarction identified using lead V4R
- Paramedic took precautions with nitroglycerin administration due to suspected right ventricular infarction
- Importance of clear communication with hospital staff and consideration of right ventricular infarction in patients with acute inferior STEMI### Identifying Acute Myocardial Infarction on ECG
Key Considerations:
- ST elevation is the primary ECG indicator of acute STEMI
- ST elevation in multiple leads suggests extensive infarct
- Reciprocal ST changes help confirm STEMI diagnosis
- Serial ECGs to monitor dynamic changes are important
Types of Acute MI Presentations:
Right Ventricular Infarction
- ST elevation in lead V1, V4-V6
- May see associated inferior STEMI
Anterior STEMI
- ST elevation in leads V1-V6
- May have high lateral extension with reciprocal changes in inferior leads
High Lateral STEMI
- ST elevation in leads aVL, I
- May have reciprocal changes in inferior leads
Low Lateral STEMI
- ST elevation in leads V5-V6
- May see reciprocal posterior changes
Isolated Posterior STEMI
- No obvious ST elevation
- Look for ST depression in right precordial leads
Mimics of STEMI
- Left bundle branch block
- Paced rhythm
- Left ventricular hypertrophy
- Early repolarization
- Pericarditis
Limitations of STEMI/Non-STEMI Paradigm
- Misses some occluded arteries that don't meet elevation criteria
- Acute occlusion myocardial infarction (OMI) concept proposed as alternative
Acute Coronary Syndromes (ACS)
- ACS occurs when blood flow to the heart is blocked, leading to heart muscle damage or death.
- Underlying pathology of ACS is atherosclerosis, a condition where plaque builds up in coronary arteries, causing inflammation and damage to arterial walls.
Atherosclerosis
- Atherosclerosis is a chronic inflammatory response to lipid-rich gruel accumulation in coronary arteries.
- Plaque growth within the innermost lining of coronary arteries can cause arterial walls to thicken, leading to a blood clot.
Plaque Rupture and Blood Clot Formation
- Plaque rupture triggers ACS, as contents come into contact with circulating blood, activating platelets and triggering clotting cascade.
- The clot can grow and eventually occlude the coronary artery, leading to a heart attack.
Clinical Presentation of ACS
- Cardinal sign of ACS is chest discomfort, described as an uncomfortable sensation, fullness, squeezing, or pressure lasting more than 15 minutes.
- Other signs and symptoms of ACS include epigastric pain, shortness of breath, diaphoresis, nausea or vomiting, palpitations or arrhythmias, and anxiety or feeling of impending doom.
Pre-Test Probability
- Pre-test probability is the likelihood of a patient having ACS based on symptoms, medical history, and other factors.
- High pre-test probability increases suspicion of ACS and warrants further investigation and treatment.
12-Lead ECG in ACS
- A 12-lead ECG is used to diagnose ACS and identify patients requiring immediate reperfusion therapy.
- ECG can show signs of ischemia or infarction, such as ST segment elevation or depression, T wave inversion, or Q waves.
Goals of Initial Management
- Goals of initial management are to restore balance between myocardial oxygen supply and demand, relieve pain and anxiety, prevent further cardiac damage, and identify patients requiring reperfusion therapy.
Reperfusion Therapy
- Reperfusion therapy, such as balloon angioplasty or thrombolytic therapy, is used to restore blood flow to the affected coronary artery.
- Goal of reperfusion therapy is to salvage myocardial tissue and reduce the risk of death and morbidity.
Identifying Acute STEMI on the 12-Lead ECG
- Acute STEMI is identified by ST segment elevation in two or more anatomically contiguous leads, reciprocal changes in the opposite leads, T wave inversion or pseudonormalization, and Q waves or significant R wave loss.
Serial 12-Lead ECGs
- Serial 12-lead ECGs help identify patients with ACS who may not have initially presented with diagnostic ECG changes.
- Changing ECG patterns suggest dynamic myocardial oxygen supply versus demand characteristics, indicating ACS.
ECG Analysis and Acute Inferior STEMI
- Acute inferior STEMI is identified by ST segment elevation in leads 2, 3, and AVF, reciprocal change in lead AVL, and a 1:1 relationship between P waves and QRS complexes.
- Importance of lead AVL in diagnosing acute inferior STEMI: 99% of the time, a reciprocal change in lead AVL will be present, and absence of this finding should question the diagnosis.
Posterior STEMI and Right Precordial Leads
- Posterior STEMI is identified by reciprocal changes in the right precordial leads (V1, V2, and V3) and ST segment depression in the right precordial leads.
Right Ventricular Infarction and Nitroglycerin
- Right ventricular infarction may occur with acute inferior STEMI, knocking out the right ventricle and making patients preload-dependent.
- Nitroglycerin administration in right ventricular infarction may drop blood pressure and worsen the condition.
Identifying Acute Myocardial Infarction on ECG
- Key considerations: ST elevation is the primary ECG indicator of acute STEMI, ST elevation in multiple leads suggests extensive infarct, reciprocal ST changes help confirm STEMI diagnosis, and serial ECGs are important.
Types of Acute MI Presentations
- Right Ventricular Infarction: ST elevation in lead V1, V4-V6
- Anterior STEMI: ST elevation in leads V1-V6
- High Lateral STEMI: ST elevation in leads aVL, I
- Low Lateral STEMI: ST elevation in leads V5-V6
- Isolated Posterior STEMI: no obvious ST elevation, look for ST depression in right precordial leads
- Mimics of STEMI: left bundle branch block, paced rhythm, left ventricular hypertrophy, early repolarization, and pericarditis
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Description
Learn about Acute Coronary Syndromes (ACS) and Atherosclerosis, including their underlying pathology and effects on the heart.
