Wiggers Diagram Explained: Heart Cycle Made Simple

Welcome to our exploration of the Wiggers Diagram, a fundamental tool for understanding the cardiac cycle.The Wiggers diagram combines four key measurements that help us understand how the heart functions during each beat.The first component shows blood pressure changes in the left ventricle and aorta.Below that, we track the volume of blood in the left ventricle as it fills and empties.The electrocardiogram, or ECG, shows the electrical activity that coordinates the heart's contractions.Finally, we record heart sounds, which occur when heart valves close. The first sound, S1, happens when the mitral valve closes, and the second sound, S2, when the aortic valve closes.These four measurements work together to give us a complete picture of the heart's mechanical and electrical activity during each cardiac cycle.During systole, the ventricular contraction cycle begins with the QRS complex on the ECG.As the ventricle contracts, left ventricular pressure rises rapidly.This rapid pressure increase causes the mitral valve to close, producing the first heart sound, S1.The aortic pressure starts higher than ventricular pressure. But as ventricular pressure continues to rise...Once ventricular pressure exceeds aortic pressure, the aortic valve opens, allowing blood to be ejected from the ventricle.During this ejection phase, we can see the ventricular volume decreasing sharply as blood is pumped out.The systolic phase continues until ventricular pressure begins to fall below aortic pressure.During this phase, approximately sixty to seventy percent of the ventricular volume is ejected into the aorta.During diastole, ventricular pressure rapidly drops below aortic pressure.This pressure drop causes the aortic valve to close, producing the second heart sound, S2.As the ventricle continues to relax, its pressure falls below atrial pressure. This pressure gradient causes the mitral valve to open.During this phase, we can observe the ventricular volume gradually increasing as the chamber fills with blood.Near the end of diastole, atrial contraction provides an additional boost to ventricular filling, visible as a small increase in both pressure and volume.Let's review the key events of diastole that prepare the heart for its next contraction.This completes our exploration of the cardiac cycle's diastolic phase.