Ann Thorac Surg 1997;63:1250
© 1997 The Society of Thoracic Surgeons
Discussion
Discussion
See also page 1243.
DR RONALD C. HILL (Morgantown, WV): This was a very nice paper and a nice presentation. Many years ago in Dr Wechsler's laboratory, we showed that pulsatile flow did not help myocardial blood flow nor renal perfusion, which is pretty much what you have found. We did not use an ischemic model, however, so you carried this a little bit farther.
What size of microsphere did you use to measure flow? If the 8- to 10-µm microsphere, normally used for hearts, is used in the brain, the results can be misleading because there are a lot of arteriovenous channels in the brain. One tends to have to use a larger microsphere, in the neighborhood of 15 µm, which may give inadequate data for the heart.
DR LODGE: Thank you for your question. We used 15-µm microspheres in this study. They have been used by our group and by others at our institution for similar studies, and in the literature, that is the most commonly used size for measuring cerebral blood flow. They were selected for this study because our primary interest was in the brain. Although this size of microsphere has been reported to overestimate subendocardial flow at the expense of subepicardial flow compared with 8- to 10-µm spheres, our measurements were of total, not regional, myocardial blood flow, which should make these differences unimportant. In addition, the same size of microspheres were used in both our experimental groups so that the differences observed should be due to the experimental conditions rather than the measurement technique.
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Regional Blood Flow During Pulsatile Cardiopulmonary Bypass and After Circulatory Arrest in an Infant Model
- Andrew J. Lodge, Akif Ündar, C. William Daggett, Thomas M. Runge, John H. Calhoon, and Ross M. Ungerleider
Ann. Thorac. Surg. 1997 63: 1243-1250.
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