Download 11_Skarvan_The aging heart: what can echocardiography tells us

The aging heart: what can echocardiography tells us about it?
K. Skarvan
Prof. emer., Cardiovascular Research Group, Department of Anaesthesia
University Hospital Basel, Spitalstrasse 21, 4031 Basel, Switzerland
[email protected]
[email protected]
Structural changes of the aging heart
In the course of the natural aging process the heart undergoes a structural remodelling, which
inevitably results in alterations of cardiac function. While in aging women left ventricular
(LV) myocardial mass as well as myocyte number, size and volume are preserved, in men
there is a progressive loss of LV both myocyte number and mass. The remaining myocytes
are subjected to an increased stress and exhibit an increase in volume and stiffness. The LV
walls become thicker and the LV changes its shape to a more spherical one. There is also an
increase in focal myocardial fibrosis and diffuse or multifocal deposits of amyloid can be
found both in the atria (isolated atrial) and ventricles (systemic senile amyloidosis).
Thickening and calcification of cardiac valve leaflets and their supporting apparatus as well as
dilation of the aortic root and the aorta are other characteristic features of the aging process.
The simultaneous aging of the arteries exposes the LV to an increased systolic load. This is
related to the increased stiffness of the aortic wall, late systolic pressure augmentation caused
by increased pulse wave velocity and reflected pressure waves increased systolic pressure.
Although the pressure overload represents a trigger of LV hypertrophy, the myocytes growth
is limited in the aging heart and may not be able to compensate for the lost myocardium.
There is no convincing evidence that the LV mass consistently increases with age. The LV
end diastolic (ED) size remains unchanged and the left atrial size does not increase until the
8th decade.
Changes in the function of the aging LV.
The LV contraction velocity is decreased and the duration of the contraction is prolonged.
However, the global and regional LV systolic functions remain well preserved. In contrast,
the diastolic function is altered and results in a progressive impairment of the early diastolic
filling. Consequently, the LV filling depends progressively more on the booster pump
function of the left atrium. Both end systolic (ES) and ED LV chamber stiffness (Ees and Eed,
respectively) are increased and likely reflect the structural changes in the aging myocardium.
The increase in Ees with age matches the parallel increase in vascular stiffening (described by
effective elastance Ea: systolic blood pressure:stroke volume) and preserves the normal
ventricular-vascular coupling (Ea/Ees). The real loss of cardiac function, however, becomes
evident only under exercise, which will unmask the progressive decrease in cardiac output
reserve (1).
Echocardiography of the aging heart
The 2-D echocardiography typically finds a normal global LV systolic function expressed as
fractional shortening (FS%), fractional area change (FAC%) or ejection fraction (EF%).
However, the mid-wall shortening corrected for LV afterload shows a weak decline and the
systolic velocity of the mitral annulus (S’) is also reduced in higher age groups. This is
associated with a decreasing longitudinal and radial LV strain and strain rate. The preload
indices, such as LV ED diameter, ED area or ED volume remain within the normal ranges.
The LV wall thickness is usually increased, particularly in the ventricular septum. The
changes in the sphericity index (length: width ratio) and the relative wall thickness (2x ED
wall thickness: ED diameter) point to the presence of LV concentric remodeling. The leaflets
of the mitral and aortic valves are thickened and there will be a varying amount of calcium
deposits in the mitral and aortic annulus. However, not more than a mild valvular
regurgitation should be present. The diameter of the aortic root is usually increased and an
atheromatosis of the ascending aorta of varying grade is usually found. Doppler
measurements of transmitral and pulmonary venous flow velocity demonstrate prolonged
isovolumic relaxation time (IVRT), decreased E, D, and increased A velocity, prolonged
deceleration time of the E wave, reduced E/A ratio, increased S/D ratio, increased atrial
emptying ratio as well as atrial ejection force. The left atrial size (diameter, area or volume)
may be increased in the very old. The early diastolic mitral annular velocity E’ decreases with
age but the E/E’ quotient should remain in the normal range (<8). These findings correspond
to a grade I of diastolic dysfunction called „impaired relaxation“. In subjects with marked
concentric remodeling, increased LV intraventricular velocities may be found in systole by
CW Doppler. The presence of mild tricuspid and pulmonic valve regurgitation allows the
estimation of the systolic and diastolic pulmonary artery pressures that should be normal. The
calculation of the stroke volume from the cross-sectional area and velocity time integral of the
blood flow velocity of the LV outflow tract should confirm the presence of a still normal
stroke volume. Nevertheless, a decline in resting cardiac index of 6-7 ml/min/m2 and year can
be expected.
Echocardiographic diagnosis of heart disease in the elderly
The echocardiography is the most important diagnostic tool for the detection of heart disease
in the aging population. The most common heart diseases of the advanced age include heart
failure (HF), calcified aortic stenosis, hypertension and coronary artery disease (CAD).
The disease related changes in the structure and function of the heart become superimposed
on the substrate of the aging heart. In patients with HF, the echocardiography should confirm
the diagnosis based on clinical and laboratory findings (BNP) and provide additional
information on the mechanism of the HF (2). The systolic HF can be separated from the aging
heart by the findings of chamber dilation, abnormal global and/or regional LV function and
signs of increased filling pressures. The common causes include CAD, valvular heart disease,
cardiomyopathy and hypertension. In the elderly, the most common form of HF is the
diastolic HF with preserved ejection fraction. However, the separation between diastolic HF
and the aging heart with diastolic dysfunction is not easy and should be based on the recently
updated recommendations for the diagnosis of diastolic HF (3). The CAD can be detected by
abnormal LW wall motion, reflecting ischemia, postinfarction scars with remodeling and
aneurysms at rest or by ischemia provoked by dobutamine stress test. The valvular lesions are
assessed according to the published guidelines (4). A calcified aortic valve without any signs
of outflow obstruction is known as aortic valve sclerosis and can be found in up to 1/3 of
subjects older than 65 years. It is associated with atheromatosis of the aorta and increased risk
of all cause and cardiovascular mortality. The patients with superimposed hypertensive heart
disease can be identified by pronounced LV hypertrophy and increased LV mass.
References
1. Lakatta EG Heart Failure Reviews 2002;7:29-497
2. ACCF/AHA Guidelines Circulation 2009;119:e391-e-479
3. EAE/ASE Recommendations Eur J Echocardiogr 2009;10:165-193
4. European Society of Cardiology Guidelines Eur Heart J 2007; 28:230-268