Following extensive infarction, the affected myocardium may become
thin and fibrotic resulting in outward bulging of the ventricular
wall during systole. Aneurysms may occasionally have mural thrombus
within the aneurysmal segment (Fig.
The presence of an aneurysm can sometimes be inferred from a
slow M-mode sweep from the base of the heart toward the apex,
in which the ventricular cavity size is seen to increase markedly
toward the apex.
However, two-dimensional echocardiography has largely supplanted
the M-mode approach. Aneurysms are most commonly found in the
septal, apical, and lateral regions, and thus are best visualized
using the parasternal or apical long-axis and four-chamber approaches.
As well as the Presence of a region where the wall is thin and
dyskinetic, the best criterion for diagnosis of a true aneurysm
is the presence of a "hinge", where there is a transition from
normal to akinetic or paradoxical wall motion. (Fig.
57) shows an apical four-chamber view with the heart normal
in diameter at the base and a massive left ventricular aneurysm
involving the distal two-thirds of the chamber.
Echoes suggestive of clot are frequently seen in the apical region,
or attached to the septum, in patients with ischemic disease and
poor left ventricular function.
58) shows a layered mural thrombus at the apex while (Fig.
59) shows a multilobulated thrombus or thrombi at the apex.
It has been shown that the multilobulated presentation of a
mural thrombus, particularly one with rapidly moving intracavitary
components, has a higher incidence of peripheral embolization.
Data is still inconclusive as to the need for, or benefit of,
anticoagulation in patients with mural thrombi in the setting
of myocardial infarction.
Another presentation of mural thrombus is when the morphology
of the thrombus is "web-like". Such a thrombus is seen filling
most of the left ventricular cavity in a patient with severe ischemic
cardiomyopathy in (Fig.
60). Such thrombi are, however, more commonly restricted to
the area of the ventricular apex.
Mural thrombi are almost invariably associated with an underlying
wall-motion abnormality. Occasionally, chest wall reverberations
make adequate interrogation of the left ventricular apex quite
difficult, and the diagnosis of apical mural thrombus is best
left to experienced observers.
While the sensitivity and specificity of the echocardiographic
diagnosis of ventricular thrombus are not known precisely, there
is a growing abundance of data that this approach is the most
clinically reliable method currently available.