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Ann Thorac Surg 2001;72:978-979
© 2001 The Society of Thoracic Surgeons

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Correspondence

Fluorescein retinal angiography as a useful method of observing cerebral perfusion during aortic arch surgery

^a Department of Cardiovascular Surgery, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita, 565-8565, Osaka, Japan

e-mail: ohnot{at}hsp.ncvc.go.jp

To the Editor

We read with great interest the article by Dong and colleagues [1] in which they observed retinal circulation of 6 piglets during retrograde cerebral perfusion (RCP) using fluorescein retinal angiography. We previously showed, with use of fluorescein retinal angiography, that RCP did perfuse in a retrograde manner through the human brain during deep hypothermic circulatory arrest [2].

In their article the authors reported that the RCP flow rate was regulated to maintain a perfusion pressure of 25 mm Hg at 5.5 to 9.5 mL/kg per minute, and that the time between injection of fluorescein and the appearance of fluorescein in the central veins (SVC-retina time) was 2.5 minutes in all piglets. In our study RCP flow was maintained at 18 to 20 mm Hg in the internal jugular vein and the flow ranged from 150 to 500 mL/min. In contrast to their results, we have found that there was a variety of SVC-retina time that ranged from 170 to 360 seconds. The RCP flow rates and SVC-retina time correlated inversely (r = 0.991, p = 0.001). Furthermore, although they showed the appearance of fluorescein in venules and arterioles, they did not identify the appearance of fluorescein in capillaries. They need to demonstrate, that during the course of angiography, fluorescein was seen sequentially in the retinal capillaries and arterioles in a retrograde way, to prove that RCP really perfuses porcine brain.

We entirely agree with the authors that fluorescein retinal angiography is a useful method of observing cerebral perfusion. However, in our experience, observing human retina with a use of fluorescein retinal angiography during aortic arch surgery is not easy and needs a profound knowledge about human eye and ophthalmologic skill. In our study, we used a portable fundus camera (Kowa, Genesis, Tokyo, Japan) to take rapid sequential retinal photographs, and we recommend it in a clinical study. Furthermore, we have found that a large proportion of older patients had cataracts, and it prevents one from observing the retina. Therefore, in our study, all patients were young and without cataracts (mean age 35.4 years; range 22 to 50 years) and patients’ diagnosis was limited to Marfan syndrome, Takayasus disease, and Behçet disease. In addition, we could not observe the retinal circulation of older patients with such conditions as aortic arch dissection. Among older patients, after cataract surgery their retinal circulation would be observed.

Because the retina develops from the forebrain, retinal circulation is thought to represent cerebrovascular circulation. Therefore we believe that fluorescein retinal angiography is a useful method of observing cerebral perfusion directly during aortic arch surgery.

References

1. Dong P., Guan Y., Yang J., He M., Wan C. Fundus microvascular flow monitoring during retrograde cerebral perfusion: an experimental study. Ann Thorac Surg 2000;70:1478-1482.
2. Ono T., Okita Y., Ando M., Kitamura S. Retrograde cerebral perfusion in human brains. Lancet 2000;356:1323.

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This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ono, T. Search for Related Content PubMed Articles by Ono, T. Related Collections Cerebral protection Related Article