Representative case of coronary flow velocity and pressure measurements in the left anterior descending coronary artery at each condition. We have defined average peak velocity, diastolic velocity, systolic velocity, diastolic time, systolic time, diastolic velocity time integral (VTI), and systolic VTI. Control indicates atrial pacing in patients with left bundle-branch block or sequential atrial and right ventricular pacing in patients with complete atrioventricular block, and biventricular pacing (BiV) indicates sequential atrial and biventricular pacing. Red line indicates aortic pressure; yellow line, coronary pressure; blue line, coronary flow velocity. ECG, electrocardiogram.