The Wright Cardiac Cycle Table: A Novel Tool to Teach the Cardiac Cycle

The Wiggers Diagram has been the standard tool for teaching the events of the cardiac cycle for nearly 100 years. However, as it often displays related cardiac cycle events on different figures in the diagram, many students have trouble grasping how these components work together to pump blood into arteries. The Wright Cardiac Cycle Table is a new teaching tool that provides a more integrative view. In this four‐row stacked‐figures table, each row displays the events that occur in each phase of the cardiac cycle. From top to bottom, the rows depict the compartmental pressures and other events of 1) slow passive filling of a ventricle (atrial and late ventricular diastole); 2) active filling (atrial systole); 3) active ventricular emptying (ventricular systole); and 4) rapid filling (atrial/early ventricular diastole). Each column represents one of four compartments (venous, atrium, ventricle, and artery) placed in a linear orientation. In the top row (slow filling in diastole), pressures in each compartment are displayed which demonstrate why the atrioventricular valve is open and the other valve (pulmonic or aortic) is closed. A blood bolus is shown following its pressure gradient from the venous compartment into the atrium. The second row displays changes in pressures following the P wave (active filling/atrial systole) and the bolus moving into the ventricle. The third row (ventricular systole) follows QRS. It displays changes in pressures, valve openings and closings, heart sounds, and blood flow from ventricle to artery during this phase. Finally, following the T wave actions of the rapid filling phase of early ventricular diastole are displayed. When the four different rows are stacked one below another the ECG is represented vertically as each wave drives the events of the subsequent phase. One can then track either each column to note which events occur in each compartment over time, or each row for the events that occur in every compartment in each phase of the cardiac cycle. Either the right or left heart can be depicted. Pathologies (e.g. aortic stenosis) can be demonstrated from the point of view of pressure change and/or fluid flow change. If animated, one can also represent filling and emptying of the chambers to further demonstrate changes in volumes of the atrium and ventricle during the cycle. One can also insert start/end volumes numerically into the table but this is not recommended. For sheer detail, nothing can truly replace the Wiggers Diagram. Still, this table has potential to supplement the Wiggers Diagram and reach a population of students who need a more concrete depiction of the cardiac cycle. The author has used this table as a medical teaching tool with great success. Future studies may more adequately assess its effectiveness across a wider group of students.