Simple non-invasive methods for obtaining the intensity and timing of arterial pulse waves

Abstract

Contraction of the left ventricle of the heart increases aortic root blood pressure (P), diameter (D) and blood velocity (U). When contraction diminishes, all three properties decrease. These perturbations propagate down the systemic arteries as the S wave and D wave, respectively. Peak carotid artery S-wave intensity is diminished and delayed in heart failure with reduced ejection fraction (HFrEF). A clinical trial demonstrated that these changes can be used to detect HFrEF with high sensitivity and specificity. Assessment of wave intensity and timing conventionally requires high-frequency, temporally and spatially coincident measurement of changes in P and U or D and U over the cardiac cycle. The practical difficulty of making such measurements accurately and noninvasively limits clinical utility. Here we test simpler methods by using numerical models of wave propagation and data from the clinical trial. We show that methods based on measuring only one of P, D or U can provide good surrogates for the full P-U and D-U methods. The best results were obtained when using measurement of D to assess wave timing. That gave Receiver Operating Characteristics (ROCs) indistinguishable from those based on the full D-U method, with areas under the ROC of up to 0.905 when timing was anchored to the ECG rather than to other waves. Measuring vessel diameter over the cardiac cycle is technically simple and would be a cost-effective way of screening for HFrEF in primary care. Other metrics, similarly measured, might also allow screening for heart failure with preserved ejection fraction (HFpEF).