An Assessment of the relationship between dicrotic notch timing and cardiac preload

Cardiovascular disease (CVD) patient outcomes can be improved by extracting and synthesizing as much useful information as possible from a limited number of available measurements. An important metric in assessing the pathological state of CVD patients is cardiac preload. Left ventricular preload can be estimated through the surrogate measurement of left ventricular end diastolic volume (LVEDV). However, cardiac volumes are difficult to measure, clinically. This study develops a 3 parameter model relating the location of the dicrotic notch in the aortic waveform to LVEDV. This model was constructed using data from porcine experiments (N = 5 pietrain pigs, weights 20-28kg). The median difference between the observed LVEDV and modelled LVEDV was 5.4%, with a 100% range of 3.0% to 15.1%. Model parameters varied between individuals as well as contractile states. The median correlation was ρ = 0.77, with a minimum of 0.58 and maximum of 0.95. This model could be used to estimate prseload from the commonly measured aortic pressure waveform.