wiggers diagram wiggers diagram 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. 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: blood pressure aortic pressure ventricular pressure atrial pressure ventricular volume electrocardiogram arterial flow (optional) heart sounds (optional) a wiggers diagram modified from the wiggers diagram clearly illustrates the coordinated variation of these values as the heart beats, assisting one in understanding the entire cardiac cycle. events phaseekgheart soundssemilunar valvesatrioventricular valves aatrial systoleps4*closedopen bventricular systole – isovolumetric/isovolumic contractionqrss1 ("lub")closedclosed c1ventricular systole – ejection 1stopenclosed c2ventricular systole – ejection 2topenclosed dventricular diastole – isovolumetric/isovolumic relaxation–s2 ("dub")closedclosed e1ventricular diastole – ventricular filling 1–s3*closedopen e2ventricular diastole – ventricular filling 2–closedopen note that during isovolumetric/isovolumic contraction and relaxation, all the heart valves are closed; at no time are all the heart valves open. *s3 and s4 heart sounds are associated with pathologies and are not routinely heard. additional images ventricular systole cardiac diastole ecg the ekg complex. p=p wave, pr=pr interval, qrs=qrs complex, qt=qt interval, st=st segment, t=t wave wiggers with jugular venous waveform