We developed a high-flow carotid shunt tube, which is thin-walled and tapered to four different sizes at the internal carotid end (3.5mm, 3.0mm, 2.7mm and 2.4mm in outer diameter).In experimental measurement using artificial blood (30% glycerine solution), the flow of the shunt tube was 4.1 times the Furui shunt, 3.0 times the Sundt shunt and 1.6 times the Javid shunt in comparison to similar outer-diameter tubes. Even the smallest shunt (2.4 mm tube) gave adequate flow for one cerebral hemisphere of over 300 ml/min for a static pressure gradient of 80 mmHg across the shunt.
In clinical use of the shunt, flow measurement of the shunts is made by inserting a 3 mm probe of an electromagnetic flow meter by cutting the shunt in half. In this way, we easily achieved an online accurate determination of carotid shunt flow.
Combined application of the high-flow shunts and their continuous flow measurement might allow detection not only malfunction of the shunts but hyperperfusional states of the brain. Accordingly, knowing the actual blood flow of the shunt, hyperperfusion syndrome might be inhibited by maintaining blood pressure at a lower level during and after the operation. It was satisfactorily used in all 13 cases, 14 operations.
