Cerebral Micro-emboli Detection
after Cardiac Surgery
(A prospective follow-up study)

Occurrence of Embolic CVA's after heart surgery is a result of slipping thrombi
caused by surgery vascular wall and heart valve damage. These sources of
embolism during and after a CABG is particular caused by the mechanical damage
of the great vessels. For valve replacement is particularly the implanted valve
a potential source of thrombus formation. Also arrhythmias activate already
present embolism sources. Atrial fibrillation (AF) is a known risk factor for
post-operative embolic CVA (so Paroxysmal AF can be a trigger for a cerebral
embolism from a pre-existent thrombus in the left heart ear).
The incidence of embolic CVA after heart surgery depends on the type of
surgery. The chance of a STROKE after CABG is in the Dutch cardiac surgery
centers between 0.3% and 1.3%. For aortic and mitral valve replacement is the
rate between 0.3% and 2.1%, while in a combined procedure (valve replacement
and CABG) the highest rates are observed (between 0.3 and 2.8%). Apparently,
complexity of the surgery has a relationship with the occurrence of a CVA.
The occurrence of a Embolic CVA after heart surgery is difficult to predict
because there is no simple method is to detect the instability of vascular
lesions. Heart rhythm disorders are easy to detect by ECG, but the predictive
value of AF on causing an embolic CVA is very low because AF occurs also in
patients with stable vascular lesions.
In recent years, a technique is developed to detect indirectly unstable lesions
in patients: the TCD emboli detection. With TCD it is possible to detect, on a
non-invasive way, the cerebral embolism of originally unstable vascular wall
lesion. Assuming of the possibility to detect asymptomatic cerebral micro
emboli hours to days before a stroke, TCD emboli detection is a method that
potentially could be used to shows an increased risk of postoperative embolic
CVA. When it is possible with TCD emboli detection to identify a group of
patients with a high risk for post-operative embolic CVA after a heart surgery
at an early stage, it is possible to develop a strategy for high risk patients
to perform an intervention for reducing the risk on a post-surgery CVA.

To demonstrate the added value of TCD emboli detection in patients after
cardiac surgery. To investigate the possibility of an early detection of silent
cerebral embolization after a cardiac surgery procedure to identify a subset of
patients with an increased risk of a post surgically embolic CVA.

A prospective observational study with a TCD Holter monitor (TCDx) in patients
in the early postoperative phase after heart surgery or TAVI. The TCDx
investigation will be done in the first 4 hours after the surgery when the
patient is hospitalized on the Intensive Care unit (ICU).

This study will be provide information if TCD emboli detection can be used in
risk stratification of the occurrence of a embolic CVA. There are no advantages
or disadvantages for the patient. TCD research is an easy-to-use non-invasive
analysis of the cerebral blood stream by ultra sound.