Effects of aging on left atrial reservoir, conduit, and booster pump function: a multi-institution acoustic quantification study

Abstract

Objective-To assess the feasibility of measuring left atrial (LA) function with acoustic quantification (AQ) and then assess the eVects of age and sex on LA reservoir, conduit, and booster pump function. Patients and setting-165 subjects without cardiovascular disease, 3-79 years old, were enrolled by six tertiary hospital centres. Interventions-Continuous LA AQ area data were acquired and signal averaged to form composite waveforms which were analysed oV-line. Main outcome measures-Parameters of LA performance according to age and sex. Results-Signal averaged LA waveforms were suYciently stable and detailed to allow automated analysis in all cases. An age related increase in LA area was noted. LA reservoir function did not vary with age or sex. All parameters of LA passive and active emptying revealed a significant age dependency. Overall, the passive emptying phase accounted for 66% of total LA emptying ranging from 76% in the youngest to 44% in the oldest decade. LA contraction accounted for 34% of atrial emptying in all subjects combined with the older subjects being more dependent on atrial booster pump function. When adjusted for atrial size, there were no sex related diVerences in LA function. Conclusions-LA reservoir, conduit, and booster pump function can be assessed with automated analysis of signal averaged LA area waveforms. As LA performance varies with age, establishment of normal values should enhance the evaluation of pathologic states in which LA function is important. (Heart 2001;85:272-277) Keywords: aging; atrium; echocardiography Left atrial (LA) performance is complex and includes functioning as a reservoir, conduit, and booster pump at diVerent stages of the cardiac cycle. Abnormalities of LA performance are clinically important and found in a wide variety of common clinical conditions such as atrial fibrillation, dilated cardiomyopathy, diastolic dysfunction, and valvar heart disease.1-5 Detailed evaluation of LA function has been performed using a variety of invasive methods which combine LA pressure with volume measurement to generate pressuredimension loops.6 7 This approach is limited by the need for direct LA pressure recordings which precludes routine clinical use.The most commonly used non-invasive technique to evaluate LA performance is Doppler echocardiography. However, Doppler echocardiography is limited since it provides no information about LA size and, although the use of this technique to evaluate LA booster pump function has been described, it is not suitable for the assessment of the reservoir and conduit phases of LA function. Measurement of LA size at diVerent phases of the cardiac cycle has proven to be useful for evaluating LA performance. However, the assessment of LA volume by two dimensional (cross sectional) echocardiography requires tedious hand tracing of endocardial borders.Acoustic quantification (AQ), an automated border detection technique, provides on-line continuous cardiac chamber area or volume over time and has been used extensively to study t...

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