Use of the indirect axillary pulse tracing for noninvasive determination of ejection time, upstroke time, and left ventricular wall stress throughout ejection in infants and young children.

The use of indirect axillary pulse tracings was investigated as an alternative method to record the carotid pulse in infants and young children. Simultaneous high-speed recordings of ascending aortic pressure and indirect axillary pulse tracings with noninvasive peripheral blood pressures were recorded in 30 young children (aged 1 day to 48 months, median 9 months) during cardiac catheterization. In 15 patients, simultaneous left ventricular (LV) M-mode echocardiograms and phonocardiograms were also performed. Systolic ejection time (SET) and the half-time of the pulse upstroke determined by both methods were compared. Computer analysis of digitized echocardiographic and pulse tracing data was used to generate plots of LV wall stress throughout ejection. Values for wall stress derived from calibrated indirect axillary pulse tracings were compared with those derived from central aortic pressure. SET calculated from axillary tracings was within 5% of the aortic value in 91% of cases, with a mean error for all subjects of -1 +/- 3%. The half-time of the pulse upstroke was within 15% of the aortic value in 91% of cases, with a mean error for all subjects of 6 +/- 12%. LV wall stress was compared at the onset of ejection, peak wall stress, midsystole, and endsystole for each patient, and 98% of values calculated from axillary data were within 10% of the wall stress values calculated from aortic pressure measurements. Thus, indirect axillary pulse tracings provide an excellent representation of the aortic pressure contour and can be used for accurate calculation of SET.(ABSTRACT TRUNCATED AT 250 WORDS)