What Is Impedance Cardiography?

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  • Written By: Mary McMahon
  • Edited By: Shereen Skola
  • Last Modified Date: 10 April 2019
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Impedance cardiography is a monitoring technique that provides information on blood flow through the aorta, corresponding to heart function. Equipment used in this monitoring approach can be used at home or in a hospital environment and is non-invasive in nature. It can also be cost effective, which may be a consideration for facilities where reliable monitoring of patients with heart problems is needed, but budgets for expensive equipment may be limited. Readouts from impedance cardiography equipment may display on a screen next to the patient or be transmitted remotely for monitoring at a nursing station.

The patient wears four pairs of sensors on the neck and thorax. These pass current through the chest, where it follows the blood through the aorta because blood is highly conductive and offers minimal electrical resistance. As the heart beats, blood volume changes and so does the resistance in the aorta, allowing the equipment to measure these changes and generate a waveform. This provides information about the patient’s cardiac output.


A medical provider can use impedance cardiography for a study on the patient’s heart function, to learn more about the nature of a specific problem and which aspects of the heart are involved. In monitoring settings, equipment can be set to flag particular changes of concern. For patients with serious heart conditions, impedance cardiography can be used to quickly identify a shift in the heart function that might indicate distress or a worsening of the condition. Nurses and other medical practitioners can intervene to treat the patient.

Like other equipment used for monitoring, the machines can be set to alarm in emergency situations. If the patient’s heart stops beating, becomes highly irregular, or exhibits other extreme abnormalities, the machine will summon a nurse or doctor. Medical personnel can monitor the success of treatments by seeing how the heart responds on the monitor as well as assessing the patient with physical examinations and observation. Once the patient is stable, they can determine why the heart started experiencing a decline in function and whether there are specific actions they can take to address the problem.

This method can be very reliable when the sensors are applied appropriately and personnel receive training in how to use impedance cardiography. They need to be able to read the waveform and accompanying electrocardiogram to understand what the data mean and interpret the information. By examining records, medical providers can measure characteristics like stroke volume with each heartbeat, which can be useful when assessing a patient’s cardiac health and risks.



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