An Assessment of Cerebrovascular Reserve Capacity after EC- IC Bypass with TCD

Czech version

Authors: M. Sameš ¹; R. Bartoš ¹; P. Vachata ¹; A. Zolal ¹; F. Cihlář ²; M. Derner ²; V. Pavlov ²
Authors‘ workplace: Neurochirurgická klinika, UJEP a Krajská zdravotní a. s., Masarykova nemocnice v Ústí nad Labem, o. z., 2Radiodiagnostické oddělení, Krajská zdravotní a. s., Masarykova nemocnice v Ústí nad Labem, o. z. ¹
Published in: Cesk Slov Neurol N 2009; 72/105(4): 359-363
Category: Original Paper

Overview

Aim:
To assess the status of cerebrovascular reserve capacity (CVRC) three months after extra-intracranial bypass (EC-IC) when compared to a reference group of hemodynamically non-compromised patients, and to assess the influence of the angiographic level of bypass fulfillment on the resulting CVRC.

Patient group and methods:

In the years 2005 and 2006, 18 EC-IC bypasses were done on patients for hemodynamic ischemia. The basic technique for CVRC testing was a transcranial Doppler test (TCD) of the middle cerebral artery (ACM). The vasomotor load was a mixture of 7.5% CO2 and 92.5% O2; we used the Ringelstein technique for the calculations. The reference group consisted of 12 volunteers. Perfusion CT was used as the correlating test. During hospitalization we correlated bypass flow for TCD and as a standard with DSA. We assessed the angiographic functionality using the Schmiedeke grade of 0–3. Perioperative mortality and significant mortality was non-existent.

Results:
DSA done early after the operation confirmed flow of all the bypasses; 3 patients (17%) achieved the first grade, 5 patients achieved the second grade (28%) and 10 patients achieved grade 3 (56%). The average percentage of Vmean ACM growth was 36% compared to 10% before the operation. The median of increase in Vmean ACM upon inhalation of CO2 in grade 1 bypasses was 39% with an SD of 9.6; grade 2 bypasses demonstrated an increase of 29% with an SD of 24.4, while a 29% increase and an SD of 11.8 was demonstrated with grade 3. There was no statistically significant difference in Vmean ACM upon inhalation of CO2 for individual levels of angiographic achievement of bypasses (p = 0.88). Those patients who were assessed early-on as grade 1 had the DSA repeated a year later; all of these patients experienced an increase in flow and a shift to grade 3.

Conclusion:
EC-IC bypass restores CVRC with a very low rate of morbidity and mortality. The primary level of angiographic achievement of bypass is not definitive. A bypass increases flow in relation to perfusion demands.

Key words:
EC-IC bypass – transcranial Doppler sonography

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