Impedance Cardiography is spelled as /ɪmˈpiːdəns kɑːdiˈɑːɡrəfi/. The word 'Impedance' is pronounced as /ɪmˈpiːdəns/ and means the total resistance offered by a circuit to the flow of an alternating current. The term 'Cardiography' is pronounced as /kɑːdiˈɑːɡrəfi/ and refers to the process of recording the electrical activity of the heart. Together, Impedance Cardiography refers to the non-invasive measurement of the mechanical activity of the heart using electrical impedance. This technique can be useful in assessing the cardiac function of patients.
Impedance cardiography is a noninvasive medical technique used to measure the cardiovascular parameters of an individual. It involves the measurement of electrical impedance changes within the body to obtain information about the heart's functioning.
Impedance cardiography operates on the principle that blood is a good conductor of electricity, whereas the surrounding tissues are relatively poor conductors. By passing a low-intensity, high-frequency electrical current through the chest, the device measures the impedance of the thorax, i.e., the resistance to the flow of electricity. Variations in the impedance waveform provide data on heart-related parameters such as stroke volume, cardiac output, and thoracic fluid content. These calculations are based on changes in the thoracic impedance caused by the movement of blood within the chest.
The procedure involves placing a set of electrodes on the body surface, usually on the neck and thorax, which enables the device to send and receive electrical signals. Impedance cardiography is regarded as a safe and noninvasive method, as it does not require any injections or invasive measurements. It is often used in clinical settings to assess cardiac function in individuals with heart failure, monitor fluid status, evaluate the effectiveness of certain cardiac treatments, and guide adjustments to medication dosages. However, it should be noted that impedance cardiography does have some limitations and may not provide as precise data as invasive methods or other imaging techniques.
The word "impedance cardiography" can be broken down into two parts: "impedance" and "cardiography".
1. Impedance: The term "impedance" comes from the Latin word "impedire", meaning "to hinder" or "to obstruct". In physics and electronics, impedance refers to the measure of opposition or resistance to the flow of an alternating current (AC) in a circuit.
2. Cardiography: The term "cardiography" is derived from the combination of two Greek words, "kardia" meaning "heart" and "graphein" meaning "to write" or "to record". Hence, cardiography refers to the process of recording or measuring the activity or characteristics of the heart.