Contrast echocardiography and vortex imaging in patients with left ventricular assist devices; single-center observational prospective study into detection of intracardiac thrombosis

Left ventricular assist devices (LVAD*s) have been increasingly become an
important therapeutic option of end-stage heart failure. However, pump
thrombosis (PT) and/or thromboembolic events (TE) defined as ischemic stroke
and transient ischemic attacks, remain life-threatening complications.
Thromboembolic events including ischemic stroke, and acute pump thrombosis rate
varied between 1 and 13.9% among different studies of continuous flow LVAD's
with either axial or centrifugal flow. Unrecognized LV thrombus at the time of
LVAD implantation could be trapped into a LVAD and results in pump dysfunction,
haemolysis, pump thrombosis, stroke, or peripheral embolism. There is currently
no golden standard in detection of intra cardiac or pump related thrombi in
LVAD patients due to suboptimal imaging of the cavities, inflow and outflow
cannula. However, early detection of these thrombi could help in the proper
management of these LVAD patients.
Contrast echocardiography (CE) is increasingly used in LV opacification and
endocardial border definition in patients with technically suboptimal
echocardiograms. Current literature is however, scarce in use of contrast
agents in LVAD patients, In a small sample of LVAD patients undergoing
clinically indicated echocardiography, CE was feasible and safe with improved
image interpretation. Furthermore, intraventricular blood flow dynamics could
be better detected with use of vortex imaging, by using particle image
velocimetry (PVI) in case of suboptimal imaging. Recent studies with PVI in
acute myocardial infarction are very promising. This technology has yet to be
validated for LVAD patients. In our study, we would like to evaluate the
clinical use of these early detection methods in patients with continuous flow
LVADs(cf-LVADs) devices.

The primary objective of this study is to identify in which imaging modality,
including CE and vortex imaging, could help us in the early diagnoses of
intracardiac thrombosis in LVAD patients. We attempt to provide a more
dedicated method for the early detection of thrombosis in LVAD.

Single-center prospective observational study

Patients will receive ultrasound contrast agent through an intravenous
infusion. The echo contrast study takes approximately 30 minutes. Patients will
be invited to participate and with permission of the patient clinical data from
the clinical interview and physical examination may be retrieved from the
medical files. The study is an observational diagnostic study, physical and
physiological discomfort for the patients is very limited. The
ultrasound contrast agent is safe and registered for the routine clinical use
in echocardiography.
There is a small risk of an allergic reaction after administration of
ultrasound contrast agent (0.01%).17 During all examinations a medical doctor
will be present to react immediately in case of an allergic reaction.
Additional blood tests will not be required. The risks associated with
participation can be considered negligible and the burden can be considered
minimal.