Flow-controlled therapeutic embolization: a physiologic and safe technique.

A feared complication of therapeutic embolization is loss of control of one or more particles with resultant ischemic infarction of normal tissues. To avoid passage of emboli into normal arteries, the delivery catheter may be wedged tightly into the artery or the artery completely occluded with a balloon catheter during embolus injection. These techniques, termed occlusion control, were a valuable forward step and significantly enhanced patient safety. However, occluding the vessel completely may cause spasm, and allows the operator to introduce fluid and emboli under higher than normal perfusion pressures which can open extra- to intracranial shunts and cause disastrous intracranial embolization. A further refinement is suggested. First, the emboli are suspended in contrast agent; then the particles are introduced while arterial runoff of the contrast agent is watched so the acceptance rate of the artery is not exceeded. Normal perfusion pressures and flow then carry the embolus distally into the abnormality being treated. This technique is safe, easily learned, and gives the radiologist direct vision control over the embolization process. It has been used in39 patients with only one serious complication.