A Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. [1] [2] In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid:
The Wiggers diagram clearly illustrates the coordinated variation of these values as the heart beats, assisting one in understanding the entire cardiac cycle. [1]
Phase | EKG | Heart sounds | Semilunar valves | Atrioventricular valves | |
A | Atrial systole | P | S4* | closed | open |
B | Ventricular systole – Isovolumetric/isovolumic contraction | QRS | S1 ("lub") | closed | closed |
C1 | Ventricular systole – Ejection 1 | ST | open | closed | |
C2 | Ventricular systole – Ejection 2 | T | open | closed | |
D | Ventricular diastole – Isovolumetric/isovolumic relaxation | – | S2 ("dub") | closed | closed |
E1 | Ventricular diastole – Ventricular filling 1 | – | S3* | closed | open |
E2 | Ventricular diastole – Ventricular filling 2 | – | closed | open |
Note that during isovolumetric/isovolumic contraction and relaxation, all the heart valves are closed; at no time are all the heart valves open. [1] *S3 and S4 heart sounds are associated with pathologies and are not routinely heard.