Effect of increasing age on diastolic motion of the left ventricular atrioventricular plane in normal subjects

Abstract

Atrioventricular plane displacement ‘long axis’ has proved an important component of the overall ventricular function. Its importance comes from the fact that it represents the subendocardial layer of the myocardium where the conduction system runs and which is sensitive to ischaemia. Assessment of long axis function is also easy and objective, particularly in diastole. As part of the ventricle, long axis function is likely to be affected by age [ [1] Owen A. Effect of increasing age on diastolic motion of the left ventricular atrioventricular plane in normal subjects. Int J Cardiol. 1999; 69: 127-132 Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar ]. This could explain the associated changes in ventricular filling pattern commonly seen in the elderly. Therefore, it is important to determine ageing changes of long axis function before considering any abnormality significant. It is generally agreed that age slows down myocyte's contraction and relaxation velocities and the cell itself tends to hypertrophy. The sum up of these individual cellular changes in a myocardial segment could be demonstrated in the form of slow shortening and lengthening rates. Furthermore, these changes, though global, are not usually of similar extent at different segments of the ventricle. Long axis motion of the free wall of the two ventricles is brought about by thickening and thinning of the subendocardial longitudinal fibres, bringing the mitral and tricuspid rings towards the ventricular apex in systole and away from it in diastole [ [2] Henein M. Gibson D.G. Normal long axis function. Heart. 1999; 81: 111-113 PubMed Google Scholar ]. The main opponent to this force is the respective lengthening and shortening of the pectinate muscle fibres in the atria, which are more powerful in the right atrium compared to the left [ [3] Wang K. Ho S.Y. Gibson D.G. Anderson R. Architecture of atrial musculature in humans. Br Heart J. 1995; 73: 559-565 Crossref PubMed Scopus (161) Google Scholar ]. On the other hand septal shortening and lengthening, in addition, are influenced by muscle hypertrophy [ [4] Henein M.Y. O'Sullivan C.A. Sutton G.C. Gibson D.G. Coats A.J.S. Stress-induced left ventricular outflow tract obstruction: A potential cause of dyspnea in the elderly. J Am Coll Cardiol. 1997; 30: 1301-1307 Abstract Full Text Full Text PDF PubMed Scopus (70) Google Scholar ] commonly seen in the elderly as well as movement of the structures sharing the fibrous skeleton of the atrioventricular zone, i.e. aortic root. Changes in the intrinsic characters of the latter are likely to affect the septal movement of the ventricular long axis. It is therefore, difficult to separate the individual effect of these components on the long axis function in the elderly. The use of tissue Doppler technique may have a special use in identifying velocity values at different segments inside the cavity of the ventricle, basal, mid-cavity, and apical. Normal values could be obtained and those outside the 95% Confidence Limits for individual segments may be identified. Finally, whether other mediastinal structures have any role in influencing septal long axis function [ [1] Owen A. Effect of increasing age on diastolic motion of the left ventricular atrioventricular plane in normal subjects. Int J Cardiol. 1999; 69: 127-132 Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar ] we have no available evidence for that.