Background: Normal healthy aging results in changes in Doppler indexes of diastolic function. One widely accepted explanation for these alterations that is based on animal data is an age-associated impairment of myocardial relaxation resulting from abnormal myocyte calcium handling. However, an alternative theory based on altered left atrial compliance with aging has been proposed in which early left atrial pressure could be low in the aged heart but rise rapidly during atrial diastole, resulting in a higher late atrial pressure and thus a normal mean pressure. We sought to explore this issue directly by performing a detailed analysis of the pulmonary capillary wedge pressure waveform obtained by right-heart catheterization during 5 different loading conditions.
Methods and results: Twelve healthy elderly sedentary subjects (mean age, 69.8+/-3 years) were recruited for the seniors group. An additional 12 young sedentary subjects (mean age, 35+/-8 years) made up the young group. All subjects were rigorously screened for comorbidities. All subjects underwent transthoracic echocardiography to determine Doppler variables of early and late transmitral filling (E and A velocities) and isovolumetric relaxation time. Each subject also underwent pulmonary artery catheterization with measurement of pulmonary capillary wedge pressure waveform during 5 different loading conditions: baseline, lower-body negative pressures of -15 and -30 mm Hg, and rapid saline infusions of 10 to 15 and 20 to 30 mL/kg. Pressure was measured at 6 points of the waveform: point 1, peak of the atrial contraction (a wave); point 2, the left atrial pressure during the start of ventricular systole; point 3, peak of atrial filling (v wave); point 4, earliest left atrial pressure during ventricular filling; and the line between points 5 and 6, pressure during diastasis. Aging resulted in a decrease in the E/A ratio (P<0.001) and a prolongation of the isovolumetric relaxation time (P<0.001) as assessed by echocardiography, but there was no effect of age on pulmonary capillary wedge pressure at any point throughout the cardiac cycle (P=0.290). Specifically, at no measured point at any level of cardiac filling volume was the pulmonary capillary wedge pressure of the seniors lower than that of the young subjects.
Conclusions: We conclude that the age-related echocardiographic change of decreasing E/A ratio is not the result of a lowering of early diastolic left atrial pressure.