Two arterial effective reflecting sites may appear as one to the heart.

摘要: The relation between reflected waves and features of ascending aortic pressure waveforms impedance patterns was investigated with a modified T-tube model the systemic arterial circulation. Ascending flow descending were measured in 10 dogs under basal conditions effect an agent (methoxamine) that caused vasoconstriction increase mean pressure. A broad range amplitudes obtained. These waveshapes classified into four groups. Under conditions, cases for which prominent diastolic fluctuation present (n = 8) grouped A. Cases this absent 2) B. Groups C 4) D 3) included that, vasoconstricted did or not display, respectively, Arterial parameters estimated by simultaneously fitting to both as input. good fit obtained any case considered. After parameter estimation, forward at entrance head circulation (head upper limbs) body (trunk lower well their merger aorta determined. input compared data points from ratio corresponding harmonics flow. In some (group A), modulus phase spectra displayed two distinct minima, 0 Hz. other circumstances, these minima less (groups B C) could even appear one D). Whether appeared low frequency whether pressure, proximal heart explained presence effective reflecting sites group B, despite fact head-end body-end distinct. This happened because peaked minimum wave. D, wave moved systole superimposed on superimposition due increased pulse velocity transmission path result decreased distensibility.(ABSTRACT TRUNCATED AT 400 WORDS)