guscoira
commented
2 years ago "An electrode is a conductive pad that is attached to the skin and enables recording of electrical currents" (reference 1). An electrocardiograph device consists in several electrodes placed over the patients body and connected to a terminal which traces the signal based on the readings of the electrodes.
"An ECG lead is a graphical description of the electrical activity of the heart and is created by analysing the electrical currents detected by several electrodes." (reference 1). The corresponding diodes are placed over the body in such a way so they can picture the heart from different angles. A given set of electrodes yields a lecture channel which provides a ECG signal.
"A lead is a view of the electrical activity of the heart from a particular angle across the body. Think of a lead as a picture of the heart and the 10 electrodes give you 12 pictures. In other words, a lead is a picture that is captured by a group of electrodes. "(reference 2) ."Every lead represents differences in electrical potentials measured in two points in space." "The electrocardiograph defines one electrode as exploring (positive) and the other as reference (negative) electrode." A standard device has at least the 12-leads (10 electrodes):
- i, ii, iii: Einthoven Leads -> lead i + lead iii = lead ii. (reference 1)
- avr, avl, avf: Goldberger Leads -> Measured with the same electrodes as the Einthoven leads, they are mathematically related with them through Kirchhoff laws (reference 1)
- v1, v2, v3, v4, v5, v6: Chest leads Wilson central terminal (WCT). "Each chest lead offers unique information that cannot be derived mathematically from other leads." (reference 1)
There are alternative ECG lead systems, such as the Frank's Leads:
- x, y, z: 7 electrodes placed in the chest and the back, they trace a x,y, z coordinate system.
The dataset assigned for this project has 15 leads, corresponding to the Einthoven, Goldberger, WCT and Frank leads. Each dataset has 15 signals assigned.
The ElectroCardioGraph is a device which translates the heart beat of a patient into an electric signal. It is crucial to this project to understand at the most basic level how do they work from a signal processing perspective.