Download Left Ventricular Wall Movement Measured by Reflected Ultrasound

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Medical Research Society
found that closing volume increases with age in a
linear relationship and is unaffected by bronchodilators. Our preliminary results showed that a
satisfactory alveolar plateau and terminal increase in
133Xenonconcentration could be achieved in cardiac
patients. Closing volume is increased above the value
predicted for age in patients with left heart failure and
some of these patients, without reversible airways
obstruction, have shown a reduction in closing
volume following sympathomimetic bronchodilators.
A positive correlation was found between closing
volume and residual volume but increase in closing
volume was poorly correlated with dyspnoea index
and left heart pressures. From our preliminary results
we suggest that patients with heart disease may have
abnormal airway narrowing and that in some cases
this may reflect increased bronchomotor tone.
In asthmatic patients the traces produced are difficult to interpret but in some cases following bronchodilator aerosols a change has occurred towards a
more normal pattern. Our experience suggests that the
133Xenontechnique may be a useful method for examining airway closure in patients with heart disease.
lamella net of elastin and collagen in the media. In
addition, the decrease of the area ratio, with the
consequent partial standing wave of pressure in the
aorta, enhances the oscillatory stress components in
the wall at and above the junction. If these localized
regions of stress can no longer be distributed uniformly by the damaged interlamella net it would explain
the focal nature of atheromatous plaques and their
distribution above the junction.
In man, the area ratio of the aortic bifurcation has
been measured from aortagrams of Caucasian subjects with ages between 0 and 50 years exhibiting no
radiological or clinical signs of atherosclerosis. It is
found that the area ratio in infancy is 1.11 (close to
the expected matched value) and decreases linearly to
a value of -0.75 for subjects within the age range of
41-50 years. No significant sex difference was found.
10. LEFT VENTRICULAR WALL MOVEMENT
MEASURED BY REFLECTED ULTRASOUND
C. S. SMITHEN
and E. SOWTON
C. F. P. WHARTON,
Cardiac Department, Guy's Hospital
Movement of the posterior wall of the left ventricle
9. IS ATHEROMA A SECONDARY PHENO- was assessed using an ultrasound technique in eleven
normal subjects at rest and immediately following
MENON ?
R. G. GOSLING,
D. L. NEWMAN
and N. L. BOWDEN maximal erect exercise. Maximum posterior wall
Department of Physics, Guy's Hospital Medical School velocity was measured as the initial slope of the wall
movement from end-diastole t o end-systole, and
(Introduced by H. Keen)
posterior wall excursion was measured as the distance
An increase in aortic distensibility is observed in between the end-diastolic and end-systolic positions.
cockerels fed an atherogenic crushed egg diet. The Posterior wall velocity increased from a mean of
abnormal distensibility is correlated with the severity 37 mmjs at rest to 96 mm/s after exercise (P<O.Ol),
of the atherosclerotic lesion using an atherosclerotic and post-wall excursion increased from 4.00 mm at
index I ranging from 1 to 100. It is found that in- rest to 6.8 mm after exercise (P<0.01). The effect of
creased distensibility occurs very early in athero- heart rate alone on posterior wall movement was
genesis and reaches a maximum value around index evaluated using the technique of atrial pacing. Invalues of -40. For index values > 60 the distensi- creasing the heart rate in six patients resulted in a
bility decreases to below the normal value due to reduction in both posterior wall velocity and excurincreasing calcification and fibrosis.
sion. At identical heart rates in four patients there
The increase in aortic distensibility in early athero- was a significant increase in both posterior-wall
genesis causes a decrease in the area ratio' of the velocity and excursion during exercise compared to
aortic junction which remains as the vessel hardens. atrial pacing. Posterior wall velocity and excursion
For an equibifurcation the area ratio giving minimum were potentiated following ectopic beats and were
reflection of the pressure pulse is shown theoretically depressed after propranolol injection.
to be -1.15. Normal cockerels have aortic junction
It is suggested that changes in posterior wall movearea ratios close to this value-1.1 6&0.06 for fourteen ment reflect alterations in left ventricular function
birds-whilst eighteen diet cockerels had an average independent of heart rate, and that these changes can
area ratio of 0.86-10.06. This would be expected to be measured by reflected ultrasound.
lead to the reflection of the pressure pulse increasing
from 2% for the matched junction to 25% for the 11. THE USE OF SYSTOLIC TIME INTERVALS
diet birds, resulting in a partial standing wave of AS AN ASSESSMENT OF LEFT VENTRICULAR
pressure in the aorta with an antinode at the junction. FUNCTION IN ACUTE MYOCARDIAL INComparison of the aortic elastic moduli/pressure FARCTION
characteristics, measured in situ, for normal and diet
E. D. BENNETT,
C. S. SMITHEN
and G. E. SOWTON
cockerels suggests that an essential factor in early
Institute
of
Cardiology,
London,
W.l
atherogenesis is the partial breakdown of the interThe
systolic
time
intervals
obtained
from the arterial
* Area ratio of any vessel junction = Sum of crosssectional areas of branch vessels divided by the pressure trace, the electrocardiogram and the phonocardiogram have been shown to be useful indicators
cross-sectional area of the parent vessel.
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