Machine Measurement

This table provides information about the machine used to collect a diagnostic ECG along with the output from that machine - summary measurements (RR interval, QRS onset, etc) and machine generated reports. Each diagnostic ECG study has a waveform file (in WFDB format) and is assigned a unique study_id. This table contains a variety of columns which provide machine and measurement / report information. The study_id can be used to link to the record list (with the path to waveform), and cardiologist note.

Important considerations

• Diagnostic ECGs are available for patients from the MIMIC-IV Clinical Database. These ECGs were collected between 2008 - 2019 but have been date shifted (for de-identification) per the convention across MIMIC.
• For a given subject, all available diagnostic ECGs (inpatient and outpatient) were pulled. Therefore, a large number of the waveforms will overlap with visits in the Clinical Database but some will not.

Table columns

This information is also available in the machine_measurements_data_dictionary.csv in the MIMIC-IV-ECG project on physionet.org.

subject_id

subject_id is a unique identifier which specifies an individual patient. Any rows associated with a single subject_id pertain to the same individual.

study_id

A unique identifier for the diagnostic ECG study.

cart_id

An identifier specific to the ECG cart used to collect the diagnostic ECG waveform.

ecg_time

The time that the diagnostic ECG was collected.

report_#

A text based cardiology report generated by the ECG machine. A variable number of report #’s are expected and can be separated by blank rows.

bandwidth

The bandwidth of the ECG machine

filtering

An indicator for the filter setting

rr_interval

Time between successive R-waves (msec)

p_onset

Time at the onset of the P-wave (msec)

p_end

Time at the end of the P-wave (msec)

qrs_onset

Time at the beginning of the QRS complex (msec)

qrs_end

Time at the end of the QRS complex (msec)

t_end

Time at the end of the T-wave (msec)

p_axis

The electrical axis of the P-wave (degrees)

qrs_axis

The electrical axis of the QRS complex (degrees)

t_axis

The electrical axis of the T-wave (degrees)