Heart attack - Tests and diagnosis

A number of tests may be used to provide valuable information in someone suspected of having a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction.. Tests are vital to the diagnosisThe process of determining which condition a patient may have., may help doctors to identify any potential complications, and may give some indication of the outlook (prognosis).

The most important tests in diagnosing a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. are electrocardiographyA technique for tracing the electrical activity of the heart. Abbreviated to ECG. (ECGAbbreviation for electrocardiogram, a tracing of the electrical activity of the heart to help in the diagnosis of heart disease.) and plasmaFluid in which the blood cells are suspended. biochemical markersCertain substances found in the blood or other body fluid that indicate a disease when detected. (detected on a bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. test).[1,2]

The electrocardiogramA tracing of the electrical activity of the heart. (ECGAbbreviation for electrocardiogram, a tracing of the electrical activity of the heart to help in the diagnosis of heart disease.) is particularly useful if it is thought that someone is having a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction.. This is because it gives information about the function of the heart almost immediately, so that treatment can be given rapidly. The ECGAbbreviation for electrocardiogram, a tracing of the electrical activity of the heart to help in the diagnosis of heart disease. uses electrodes placed on the chest, which then detect the electrical activity of the heart and produce a tracing to reflect this.

Biochemical markers are specific proteins that are found in the cells of the heart muscleTissue made up of cells that can contract to bring about movement.. When the heart muscleTissue made up of cells that can contract to bring about movement. is injured, as it is during a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction., these proteins are slowly released into the bloodstream.

Testing the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. several times during the hours after a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. may show rising levels of these proteins. However, treatment of a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. must not be delayed by several hours  -  time is of the essence in order to prevent heart muscleTissue made up of cells that can contract to bring about movement. damage, and treatment must be given immediately. Because of this, an ECGAbbreviation for electrocardiogram, a tracing of the electrical activity of the heart to help in the diagnosis of heart disease. may be more useful to make a rapid diagnosisThe process of determining which condition a patient may have. in emergency.

A number of additional tests can be used to support the diagnosisThe process of determining which condition a patient may have., and may give information about the underlying cause of a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction.. For example, echocardiographyThe use of ultrasound to examine the heart as it is pumping. , a specialised ultrasound of the heart, gives valuable information about the function of the heart, and how well it is pumping.

Angiography involves injecting dye into the arteries of the heart before taking X-rays, so that any narrowing in the arteries becomes clearly visible.

Computed tomography (CTA scan that generates a series of cross-sectional X-ray images.) and magnetic resonance imagingA technique for imaging the body that uses electromagnetic waves and a strong magnetic field. (MRIAn abbreviation for magnetic resonance imaging, a technique for imaging the body that uses electromagnetic waves and a strong magnetic field.) may also be useful. Myocardial perfusion imaging can give information about the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. supply to all the regions of the heart muscleTissue made up of cells that can contract to bring about movement.. These pages will discuss all of these imaging investigations in more detail.

References: 
  1. Boon NA, Colledge NR and Walker BR. Davidson's Principles and Practice of Medicine. Churchill Livingstone Elsevier. 2006; 20th edition.
  2. Universal definition of myocardial infarctionDeath of an area of heart muscle due to poor blood supply.. Thygesen K, Alpert JS, White HD. Circulation 2007;116;2634-53.