The effects of aging on cardiac blood flow velocities are important as a description of the natural history of the aging process and as a reference for evaluation of the aging cardiovascular system. We therefore studied these effects in 215 healthy volunteers, 120 males and 95 females, between 1 and 65 years old. Pulsed Doppler signals were recorded proximal and distal to the mitral (M) and tricuspid (T) valves, in the left ventricular outflow tract (LVOT), in the ascending aorta (AAO), in the right ventricular outflow tract (RVOT), and in the pulmonary artery (PA). Systolic (S) flow velocity patterns consist mainly of one peak. Diastolic blood flow velocity is characterized by two peaks: one due to early filling (E) of the ventricle and a second as a result of atrial contraction (A). All peaks are characterized by the maximum of the median velocity curve (Vmax). With age increasing from 1 to 65 years, VmaxS decreases in the AAO (40%) and PA (10%), VmaxE decreases on both sides of the M valve (proximal-50%; distal-30%), and the T valve (proximal-20%; distal-30%). However, with increasing age VmaxS increases in the LVOT (25%), and VmaxA increases on both sides of the M valve (proximal-20%; distal-50%) and proximal to the T valve (30%). VmaxS in the RVOT and VmaxA distal to the T valve did not show a relation with age. These observations demonstrate that in a normal population Vmax in the heart and great vessels is age dependent at most sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Reproducibility of mean transit time for maximal myocardial flow assessment by videodensitometry.

In the assessment of myocardial perfusion by ECG-triggered digital radiography, time parameters are calculated from the time density curve (TDC) and related to blood flow. Recently we developed a method which uses mean transit time (Tmn) as time parameter, and which is in accordance with the original principles of indicator dilution theory. In this approach, variability in vascular volume is excluded and Tmn-1, determined at maximal hyperemia, showed an excellent correlation with maximal flow in animal validation studies. For calculation of Tmn, however, a large part of the descending limb of the TDC has to be known for reliable extrapolation, and especially this part of the curve is subject to variability in image quality in man. Therefore we tested reproducibility of Tmn in 30 arteries in 20 patients. Tmn was derived from the TDCs, obtained from paired studies under identical circumstances with an interval of 10 minutes. Satisfactory images could be obtained in all but one patient. Image processing was performed in an identical way in the paired studies. Reproducibility proved to be excellent for all three coronary arteries. The absolute value of the relative differences between the first and second determination was 7 +/- 7% for the LAD, 6 +/- 3% for LCx and 4 +/- 2% for the RCA (mean +/- SD). Correlation coefficients between both measurements were 0.97, 0.95 and 0.95 for the respective arteries. Therefore, it is concluded that, using this approach, Tmn at maximal hyperemia can be determined reproducibly in man and used for maximal myocardial flow assessment.

Absorptiometry, Photon↗