There is a broad range of diagnostic methods for identifying the various heart diseases and assessing the patient’s state of health after a stroke or a heart attack. The available tests fall into three main categories: imaging, blood flow tests and electrical tests. Imaging is used to create a picture of the affected organ (usually the brain or the heart). It gives crucial information about the cause of the incidence and the location and extent of the injury. Images may also be used to provide information before surgery. There are two techniques commonly used: computed tomography (CT or CAT Scans) and magnetic resonance imaging (MRI).
Electrical tests reveal the electrical activity of the brain or the heart. Electroencephalograms (EEGs) measure the brain's electrical activity, whereas electrocardiography (ECG or EKG) measures the electrical activity of the heart. In the case of stroke, additional electrical tests (so-called evoked response tests) that relate to how the brain handles sensory information might be conducted.
Blood flow tests usually use ultrasound technology (echocardiography) to determine the amount of blood flow through specific blood vessels. Another method is angiography, where a special dye is injected into the blood vessels, followed by X-ray photography.
The method employed depends on the specific patient's condition, the physician's preferences, and the availability of the corresponding technologies.
Echocardiography is a sonogram of the heart, or sometimes referred to as cardiac ultrasound. It uses ultrasound techniques to image two-dimensional slices of the heart. The latest echocardiography systems are also capable of three-dimensional real-time imaging. The technology allows to assess the condition of the heart and might include heart valve function, leaking of blood through the valves and calculation of the heart pump volume.
Electrocardiography (ECG or EKG)
Electrocardiography (ECG or EKG) measures the electrical activity of the heart over time, recorded by skin electrodes. ECGs are used to diagnose abnormal rhythms of the heart (cardiac arrhythmias) or determine the extent of damage of the heart muscle after a heart attack.
An EEG records the electrical activity of the brain. EEG used to be the method of choice for the diagnosing strokes, however, nowadays EEGs are more and more replaced by magnetic resonance imaging (MRI) and computed tomography (CT or CAT).
Angiography is a method to determine blood flow through the blood vessels. First a special dye is injected into the blood vessels and then X-ray pictures are taken. It allows the size and location of blockages to be evaluated. This test can be especially valuable in providing information before surgery.
Magnetic Resonance Imaging
Magnetic Resonance Imaging (MRI) is an imaging technique to visualize the internal structure and function of the body. MRIs are especially good for imaging and distinguishing the different soft tissues of the body, making them very useful to image the brain and the cardiovascular system.
Computed tomography (CT or CAT) is a medical imaging method where a three-dimensional image is assembled from a large series of two-dimensional X-ray images. CT scans might be used to diagnose strokes, blood clots, bleeding within the brain and assess blood vessel abnormalities.
Assessment of blood circulation in a coronary artery after a heart attack using positron-emission-tomography.