Aortic‐Radial Pulse Transit Time and ECG <i>Q</i>‐Wave to Radial Pulse Wave Interval as Indices of Beat‐By‐Beat Blood Pressure Change

Abstract

ABSTRACT This study examined beat‐by‐beat relationships between blood pressure, the time interval from the ECG Q‐wave to the radial pulse wave (QRPI), and its two components, the cardiac pre‐ejection period (PEP) and aortic‐radial arterial pulse transit time (AR‐PTT). In 8 subjects, intra‐arterial systolic (SBP) and diastolic (DBP) blood pressure, QRPI, PEP, and AR‐PTT were measured during rest, mental arithmetic, cold pressor, and inhalation of amyl nitrite. Both PEP and AR‐PTT varied widely during each experimental condition indicating that QRPI change reflected both PEP and AR‐PTT change. AR‐PTT varied inversely with SBP and DBP; PEP sometimes varied directly and sometimes inversely with both SBP and DBP. QRPI varied inversely with both SBP and DBP with the magnitude of the correlation in a particular instance depending on the relationships for that instance between blood pressure and both PEP and AR‐PTT. Implications of the results for the use of either QRPI or AR‐PTT as indices of blood pressure change are discussed.