The<unk>  is a marker of the function of the left ventricle of the heart. It represents the ratio of peak velocity blood flow from left ventricular relaxation in early diastole (the E wave) to peak velocity flow in late diastole caused by atrial contraction (the A wave). It is calculated using Doppler echocardiography, an ultrasound-based cardiac imaging modality. Abnormalities in the<unk>  suggest that the left ventricle, which pumps blood into the circulation, cannot fill with blood properly in the period between contractions. This phenomenon is referred to as diastolic dysfunction and can eventually lead to the symptoms of heart failure.
E/A ratio
QRS complex
Ka/Ks ratio
NC ratio
Extraction ratio
J wave
U wave
P wave 