The major finding in our study is the frequent occurrence of new postoperative, segmental, perfusion scan abnormalities in lung zones served by angiographically patent, undissected pulmonary arteries. cialis professional
The appearance of “spurious” recurrence of embolism on perfusion scan has been reported previously during the course of resolution of acute pulmonary embolism. In that study, new scan defects appeared as resolution proceeded; and it was shown angiographically that these defects reflected differential rates of embolic dissolution in different vessels. Lung scan perfusion defects resolved distal to those vessels in which rapid resolution of obstruction had occurred, while new defects appeared distal to vessels that retained significant, although partial, obstruction. These spurious recurrences were postulated to reflect a changed pattern of blood flow as a consequence of the redistribution of pulmonary vascular resistance.
In the present series, the differential resolution rates of acute emboli played no role in the “steal syndrome” because acute emboli were not demonstrated at surgery. Yet the “steal” phenomenon again appears to reflect a redistribution of flow—in this instance following surgical thromboendarterectomy. What, then, are the potential mechanisms responsible? The answers must remain speculative at this juncture, but certain insights are available.
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