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{{DISPLAYTITLE:Diagnosis of Myocardial Infarction}}
== Diagnosis of Myocardial Infarction ==


==Overview==
[[File:12_Lead_EKG_ST_Elevation_tracing_color_coded.jpg|thumb|right|12-lead EKG showing ST elevation, indicative of myocardial infarction]]
The diagnosis of [[myocardial infarction]] (MI), commonly known as a heart attack, involves a combination of clinical evaluation, [[electrocardiogram]] (ECG) findings, and measurement of cardiac biomarkers. Myocardial infarction occurs when blood flow to a part of the heart is blocked for a long enough time that part of the heart muscle is damaged or dies.


==Clinical Presentation==
The diagnosis of [[myocardial infarction]] (MI), commonly known as a heart attack, involves a combination of clinical evaluation, [[electrocardiogram]] (ECG) findings, and laboratory tests. Myocardial infarction occurs when blood flow to a part of the heart is blocked for a long enough time that part of the heart muscle is damaged or dies.
Patients with myocardial infarction typically present with chest pain or discomfort, which may radiate to the arms, neck, jaw, or back. Other symptoms can include shortness of breath, nausea, vomiting, palpitations, and sweating. However, some patients, particularly women, the elderly, and those with diabetes, may present with atypical symptoms or even be asymptomatic.


==Electrocardiogram (ECG)==
=== Clinical Presentation ===
The ECG is a crucial tool in the diagnosis of myocardial infarction. It records the electrical activity of the heart and can show changes indicative of an MI, such as ST-segment elevation, ST-segment depression, or T-wave inversions.
Patients with myocardial infarction typically present with chest pain or discomfort, which may radiate to the arms, neck, jaw, or back. Other symptoms can include shortness of breath, nausea, vomiting, palpitations, and sweating. It is important to note that some patients, particularly women, the elderly, and those with diabetes, may present with atypical symptoms or even be asymptomatic.


[[File:12_Lead_EKG_ST_Elevation_tracing_color_coded.jpg|12-lead ECG showing ST elevation|thumb|right]]
=== Electrocardiogram (ECG) ===
The ECG is a critical tool in the diagnosis of myocardial infarction. It can show characteristic changes such as ST-segment elevation, T-wave inversion, and the development of pathological Q waves. These changes help differentiate between [[ST-elevation myocardial infarction]] (STEMI) and [[non-ST-elevation myocardial infarction]] (NSTEMI).


===ST-Elevation Myocardial Infarction (STEMI)===
=== Biomarkers ===
STEMI is characterized by the presence of ST-segment elevation in two or more contiguous leads on the ECG. This indicates a full-thickness injury to the heart muscle.
[[Cardiac biomarkers]] are substances that are released into the blood when the heart is damaged. The most commonly used biomarkers for diagnosing myocardial infarction are [[troponin]] I and T, which are highly specific to cardiac tissue. Elevated levels of these biomarkers indicate myocardial injury.


===Non-ST-Elevation Myocardial Infarction (NSTEMI)===
=== Imaging ===
NSTEMI does not show ST-segment elevation on the ECG but may show other changes such as ST-segment depression or T-wave inversion. It indicates a partial-thickness injury to the heart muscle.
[[File:Ha1.jpg|thumb|left|Histopathological image showing myocardial infarction with contraction bands]]
[[File:Histopathology_of_coagulative_necrosis_of_cardiomyocytes.jpg|Histopathology showing coagulative necrosis|thumb|left]]


==Cardiac Biomarkers==
Imaging techniques such as [[echocardiography]] and [[coronary angiography]] can be used to assess the extent of myocardial damage and to identify the location and severity of coronary artery blockages. Echocardiography can also help evaluate heart function and detect complications such as heart failure or [[ventricular septal defect]].
Cardiac biomarkers are substances that are released into the blood when the heart is damaged. The most commonly used biomarkers are [[troponin]] and [[creatine kinase-MB]] (CK-MB).


===Troponin===
=== Pathology ===
Troponin is the most specific and sensitive marker for myocardial injury. Elevated levels of troponin in the blood are indicative of myocardial infarction.
[[File:MI_with_contraction_bands_very_high_mag.jpg|thumb|right|Histopathology of myocardial infarction showing contraction bands]]


===Creatine Kinase-MB (CK-MB)===
Pathological examination of myocardial tissue can reveal changes characteristic of infarction, such as coagulative necrosis, contraction band necrosis, and inflammatory cell infiltration. Gross pathology may show areas of pallor or hemorrhage in the heart muscle.
CK-MB is another marker of myocardial injury, but it is less specific than troponin. It is used in conjunction with troponin to diagnose MI.


==Imaging Studies==
[[File:Gross_pathology_of_a_one_week_old_myocardial_infarction_with_focal_rupture.jpg|thumb|left|Gross pathology of a one-week-old myocardial infarction with focal rupture]]
Imaging studies can be used to assess the extent of myocardial damage and complications of MI.


===Echocardiography===
=== Differential Diagnosis ===
Echocardiography uses ultrasound waves to create images of the heart. It can show areas of the heart that are not contracting well due to damage from an MI.
The differential diagnosis of myocardial infarction includes other causes of chest pain such as [[angina pectoris]], [[pericarditis]], [[aortic dissection]], and [[pulmonary embolism]]. It is crucial to distinguish these conditions as they require different management strategies.


===Cardiac MRI===
== Related Pages ==
Cardiac MRI provides detailed images of the heart and can assess the extent of myocardial damage and viability.
* [[Coronary artery disease]]
 
* [[Heart failure]]
==Pathology==
* [[Cardiac arrest]]
The pathological examination of myocardial tissue can provide definitive evidence of myocardial infarction.
* [[Cardiovascular disease]]
 
[[File:MI_with_contraction_bands_very_high_mag.jpg|Histopathology showing contraction bands in MI|thumb|left]]
 
===Gross Pathology===
Gross examination of the heart can reveal areas of infarction. Early infarcts may appear pale, while older infarcts may be yellow or white due to fibrosis.
 
[[File:Gross_pathology_of_a_one_week_old_myocardial_infarction_with_focal_rupture.jpg|Gross pathology of a one-week-old MI with rupture|thumb|right]]
 
===Histopathology===
Histopathological examination can show changes such as coagulative necrosis, neutrophil infiltration, and interstitial edema.
 
==Related Pages==
* [[Myocardial infarction]]
* [[Electrocardiogram]]
* [[Troponin]]
* [[Echocardiography]]


[[Category:Cardiology]]
[[Category:Cardiology]]
[[Category:Medical diagnosis]]
[[Category:Medical diagnosis]]

Latest revision as of 16:48, 5 March 2025

Diagnosis of Myocardial Infarction[edit]

12-lead EKG showing ST elevation, indicative of myocardial infarction

The diagnosis of myocardial infarction (MI), commonly known as a heart attack, involves a combination of clinical evaluation, electrocardiogram (ECG) findings, and laboratory tests. Myocardial infarction occurs when blood flow to a part of the heart is blocked for a long enough time that part of the heart muscle is damaged or dies.

Clinical Presentation[edit]

Patients with myocardial infarction typically present with chest pain or discomfort, which may radiate to the arms, neck, jaw, or back. Other symptoms can include shortness of breath, nausea, vomiting, palpitations, and sweating. It is important to note that some patients, particularly women, the elderly, and those with diabetes, may present with atypical symptoms or even be asymptomatic.

Electrocardiogram (ECG)[edit]

The ECG is a critical tool in the diagnosis of myocardial infarction. It can show characteristic changes such as ST-segment elevation, T-wave inversion, and the development of pathological Q waves. These changes help differentiate between ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI).

Biomarkers[edit]

Cardiac biomarkers are substances that are released into the blood when the heart is damaged. The most commonly used biomarkers for diagnosing myocardial infarction are troponin I and T, which are highly specific to cardiac tissue. Elevated levels of these biomarkers indicate myocardial injury.

Imaging[edit]

Histopathological image showing myocardial infarction with contraction bands

Imaging techniques such as echocardiography and coronary angiography can be used to assess the extent of myocardial damage and to identify the location and severity of coronary artery blockages. Echocardiography can also help evaluate heart function and detect complications such as heart failure or ventricular septal defect.

Pathology[edit]

Histopathology of myocardial infarction showing contraction bands

Pathological examination of myocardial tissue can reveal changes characteristic of infarction, such as coagulative necrosis, contraction band necrosis, and inflammatory cell infiltration. Gross pathology may show areas of pallor or hemorrhage in the heart muscle.

Gross pathology of a one-week-old myocardial infarction with focal rupture

Differential Diagnosis[edit]

The differential diagnosis of myocardial infarction includes other causes of chest pain such as angina pectoris, pericarditis, aortic dissection, and pulmonary embolism. It is crucial to distinguish these conditions as they require different management strategies.

Related Pages[edit]