J Thorac Cardiovasc Surg 2006;132:208-209
© 2006 The American Association for Thoracic Surgery
Is it really the number of clamps that is responsible for worse postbypass neurological outcomes?
Omer Ashraf, MBBS
Aga Khan University, Stadium Road, Karachi 74800, Pakistan
(Email: warraicch{at}yahoo.com).
To the Editor:
I read with interest the article by Dr Hammon and colleagues
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comparing varying levels of aortic manipulation in bypass surgery with regard to postoperative neurobehavioral outcomes. Even as the results are in some concurrence with certain previous trials in this direction, I do believe that this report requires careful review before its recommendations can be accepted.
First, the multiple aortic clamping group had greater age, incidence of hyperlipidemia, and aortic fibrillation than the single aortic clamping group, 3 independent predictors of postoperative stroke.
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Second, the authors were unable to demonstrate any significantly worse result in the 2 groups, apart from the neuropsychologic deficit at 6-month follow-up. Recent prospective neuropsychologic testing indicates that these late neurocognitive deficits are likely to be caused by established risk factors for cerebral vasculopathy not having anything to do with the bypass procedure itself.
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It is therefore arguable that the mere reduction in the number of clamps would have a significant effect on patient neurological profile after bypass surgery, considering that there exists already conflicting evidence, with no additional benefit of reduction in clamp number being recorded previously.
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Consensus in the literature has generally been that off-pump surgery results in better neurocognitive outcomes than on-pump procedures. Apart from the well-documented role of cardiopulmonary bypass in emboli generation, this finding might be explained by the interesting fact that it is actually the act of aortic cannulation rather than the application of the clamp itself that is likely to generate the greatest number of emboli.
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This might explain the better results in the off-pump group and the comparable results in the 2 on-pump groups with different degree of clamp use in this trial, obviating the little additional benefit of reduction in clamp number.
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References
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- Hammon JW, Stump DA, Butterworth JF, Moody DM, Rorie K, Deal DD, et al. Single crossclamp improves 6-month cognitive outcome in high-risk coronary bypass patients. the effect of reduced aortic manipulation. J Thorac Cardiovasc Surg 2006;131:114-121.[Abstract/Free Full Text]
- Hirose H, Amano A, Takahashi A. Side clamp used during off-pump coronary artery bypass does not increase the risk of stroke. Med Sci Monit 2002;8:CR235-CR240.[Medline]
- Selnes OA, Grega MA, Borowicz Jr LM, Barry S, Zeger S, Baumgartner WA, et al. Cognitive outcomes three years after coronary artery bypass surgery. a comparison of on-pump coronary artery bypass graft surgery and nonsurgical controls. Ann Thorac Surg 2005;79:1201-1209.[Abstract/Free Full Text]
- Sinatra R, Capuano F, Santaniello E, Tonelli E, Roscitano A. Occluding clamp technique during coronary artery bypass grafting. single or double-clamp technique?. Ital Heart J 2004;5:450-452.[Medline]
- Stroobant N, Van Nooten G, Van Belleghem Y, Vingerhoets G. Relation between neurocognitive impairment, embolic load, and cerebrovascular reactivity following on- and off-pump coronary artery bypass grafting. Chest 2005;127:1967-1976.[Medline]
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Reply to the Editor
- John W. Hammon
J. Thorac. Cardiovasc. Surg. 2006 132: 209.
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