Pilot-investigation: The reduction of embolic and there by neurologic complications after cardiac surgery by the use of a non-invasive imaging technique(CABG, on pump)

Patients undergoing cardiac surgery frequently develop neurologic
complications, ranging from subtle cognitive changes to evident confusion,
delirium, and stroke. This continuum of complications is commonly caused by
embolization in the brain due to manipulation of atherosclerotic parts of the
aorta ascendens (AA) during surgery. Timely detection of AA atherosclerosis
before surgery enables the surgeon to consider changes of the surgical plan, to
reduce the risk of embolization and thus subsequent neurologic complications.
Various methods exist to visualize the AA to detect atherosclerosis. Epiaortic
ultrasound scanning has become the gold standard, but is seldom used as it
affacts often to late the surgical plan and it can only be used after
sternotomy , it increases the change of an infection of the sternum.
Transesophageal echocardiography (TEE) is a widely used imaging method
permitting evaluation of the aorta preoperatively, but assessment of distal AA
is hampered by interposition of air-filled trachea between oesophagus and AA.
The A-View® (Aortic-view) method, a modification of conventional TEE using a
fluid-filled balloon, overcomes this limitation. The safety and diagnostic
accuracy of the A-View® have successfully been shown in previous studies. This
study is the logical next step to investigate more whether the use of the
A-View® method effectively reduces embolic load in the brain and thereby
neurologic complications.

This pilot is meaned to obtain:
- experience and understanding in the presence of new embolic load in the brain
by means of DW-MRI
- Understanding in the number of patients in which probably the post-operative
DW-MRI can not be done according to clinical complications (like agitation,
etc.)
After a successful pilotstudy a mainstudy will be done with 240 patients.
The objective of this mainstudy is to investigate whether use of the A-View®
method effectively reduces embolic load in the brain and thereby neurologic
complications in patients undergoing on-pump cardiovascular artery bypass
grafting (CABG) surgery.

The A-view 3 study is a single-center randomized pragmatic trial in which
patients referred for elective CABG surgery with the use of cardiopulmonary
bypass (CPB) will be allocated to either CABG surgery with the use of the
A-View® method (intervention group) or receive care as usual (i.e., without
use of the A-View® method, control group).
In the patients randomized to the intervention group the presence of aortic
atherosclerosis will be investigated by the treating anaesthesiologist before
opening the sternum, first using conventional TEE conform standard care and
subsequently with the A-View® method. The TEE plus A-View® results will be
discussed with the surgeon. Based on these results, adaptation of the treatment
strategy will take place according to a predefined protocol. Possible
adaptation strategies range from no adaptation to minor (e.g., different
position of the aortic canula; single cross clamp in stead of side biting clamp
for proximal anastomosis ), moderate (e.g., different type of aortic canula;
Off-Pump CABG), or major (e.g., hypothermic circulatory arrest with aortic
ascendens replacement; fibrillating CABG with no use of aortic cross clamp at
all; proximal anastomis stapler) surgical changes, dependent on the stage and
location of atherosclerosis.
The control group receives care as usual, i.e. regular TEE monitoring without
the A-View®method. Surgical strategy is determined conform current care.

Procedure. After written informed consent is obtained, a pre-surgery DW-MRI
scan of the brain will be made to determine the number, size and location of
lesions present before surgery. Also, Quality of Life and neuropsychologic
tests will be performed as part of the preoperative work-up. Before sternotomy,
the presence of aortic atherosclerosis will be investigated according to the
randomization group, as described above. After surgery the patient is treated
according to standard care, i.e., admission to the ICU and subsequent discharge
to the ward when possible. Between 3 and 7 days postoperatively, a second
DW-MRI scan of the brain is performed. During ICU and hospital stay, delirium
is measured according to standardized scoring instruments (ICU: Neecham*s
scale; ward: Delirium Observation Scale). All major complications are
registered during hospital stay and neurologic complications will be registered
up till 6 weeks after surgery. At six weeks post-surgery the patient will
undergo the second series of neuropsychologic tests to investigate remaining
cognitive decline and at 6 weeks Quality of Life measurement.

Procedure. After written informed consent is obtained, a pre-surgery DW-MRI
scan of the brain will be made to determine the number, size and location of
lesions present before surgery. Also, Quality of Life and neuropsychologic
tests will be performed as part of the preoperative work-up. Before sternotomy,
the presence of aortic atherosclerosis will be investigated according to the
randomization group, as described above. After surgery the patient is treated
according to standard care, i.e., admission to the ICU and subsequent discharge
to the ward when possible. Between 3 and 7 days postoperatively, a second
DW-MRI scan of the brain is performed. During ICU and hospital stay, delirium
is measured according to standardized scoring instruments (ICU: Neecham*s
scale; ward: Delirium Observation Scale). All major complications are
registered during hospital stay and neurologic complications will be registered
up till 6 weeks after surgery. At six weeks post-surgery the patient will
undergo the second series of neuropsychologic tests to investigate remaining
cognitive decline and at 6 weeksa Quality of Life measurement.

The hypothesis underlying this study is that the use of the A-View® method in
cardiac surgery patients provides better insight in the presence and grade of
AA atherosclerosis, at a timely moment to enable the surgeon to change his/her
therapeutic management. These changes - from moderate (site of aortic
cannulation or clamping) to extensive (conversion to off-pump CABG or aortic
ascendens replacement) - are hypothesized to reduce the risk of embolization in
the brain. These induced embolizations will be visualized by means of a pre-
and postoperative diffusion-weighted magnetic resonance imaging (DW-MRI). The
burden is additional diagnostic tests such as MRI. The advantage is timely
change of surgical strategy in order to prevent cerebral infarction.