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AJNR - American Journal of Neuroradiology

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Hemodynamic versus Hydrodynamic Effects of Guglielmi Detachable Coils on Intra-Aneurysmal Pressure and Flow at Varying Pulse Rate and Systemic Pressure

Angelika Sorteberg^b, Wilhelm Sorteberg^b, Beverly D. L. Aagaard^a, Alan Rappe^a and Charles M. Strother^a

^a Department of Radiology, University of Wisconsin Health Sciences Center, Madison
^b Department of Neurosurgery, Rikshospitalet, the National Hospital, Oslo, Norway

View larger version (50K): [in a new window]   FIG 1. Vascular silicone phantom with a replica of the aortic arch, brachycephalic vessels, and a cerebral basin (upper insert). The systemic pressure could be adjusted by using a clamp on the main inflow vessel (lower insert).

View larger version (50K): [in a new window]   FIG 2. Surgically created canine aneurysm after explantation mounted onto the inflow and outflow connections in the basin of the vascular model.

View larger version (69K): [in a new window]   FIG 3. The bifurcational silicone aneurysm with the 0.014-inch pressure-temperature sensor guidewire in place at the dome. The aneurysm is mounted in the basin of the vascular model. Note the flexible tip distal to the sensor that helps to maintain a stable placement of the sensor.

View larger version (69K): [in a new window]   FIG 4. Bifurcational silicone aneurysm after the insertion of GDCs. The 0.014-inch pressure-temperature sensor guidewire is still in place (arrow). The insert shows the coiled aneurysm through the microscope.

View larger version (29K): [in a new window]   FIG 5. Example of the increase in pressure in millimeters of mercury (top) and thermodilution curve in degrees Celsius (bottom) obtained from an injection of normal saline 15 mL/s over 2 seconds at room temperature. Dilution interval denotes the entire period of temperature change, T represents the largest drop in temperature achieved by injection of the saline, and is the gap between the start of pressure increase and the start of fall in temperature (dissociation of pressure and flow)

View larger version (29K): [in a new window]   FIG 6. Pressure and thermodilution curves in the canine aneurysm in vivo (top) and in vitro (bottom) before (left) and following (right) placement of GDCs. The inserts represent magnifications of the respective thermodilution curves. Before coiling, there are similar U-shaped thermodilution curves both in vivo and in vitro. After coiling, the thermodilution curves are flattened considerably both in vivo and in vitro, but more markedly in vivo.

View larger version (31K): [in a new window]   FIG 7. Increase in intra-aneurysmal pressure caused by the injection of normal saline at a rate of 5 mL/s over 4 seconds at various systemic pressures (P) and pulse rates (f), both before (left) and after (right) the insertion of GDCs. The pressure increases augmented with increasing systemic pressure and decreasing pulse rate.

View larger version (31K): [in a new window]   FIG 8. The maximum drop in temperature, T, created by injections of normal saline at room temperature at various systemic pressures (P) and pulse rates (f), both before (left) and after (right) the insertion of GDCs. Coiling significantly reduced T, which was dependent on the pulse rate but independent of the systemic pressure.

View larger version (29K): [in a new window]   FIG 9. The dissociation of pressure and flow (shift ) at various systemic pressures (P) and pulse rates (f), both before (left) and after (right) the insertion of GDCs. was independent of the pulse rate and pressure before the insertion of GDCs. With the presence of GDCs in the aneurysm, it increased depending on the pulse rate.

View larger version (29K): [in a new window]   FIG 10. The length of the dilution interval represented by the total time of change in temperature occurring after injection of 5 mL/s over 4 seconds room temperature normal saline at various systemic pressures (P) and pulse rates (f), both before (left) and after (right) the insertion of GDCs. It was not affected by variations in systemic pressure and pulse rate before GDC placement. There was a marked prolongation of the dilution interval after GDC placement at a pulse rate of 40 beats per minute with a concomitant positive correlation to the systemic pressure.