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Eur J Cardiothorac Surg 2004;26:1055
© 2004 Elsevier Science NL
Letter to the Editor |
126 rue de Picpus, 75012 Paris, France
Received 27 June 2004; accepted 27 July 2004.
* Tel.: +33-6-33-58-00-38. (E-mail: mathias.aazami{at}club-internet.fr).
I have read with great interest the retrospective clinical study of Dr De Paulis et al. which attempted to enlighten hypothetic prompting effects of pseudo-sinuses on coronary blood flow [1].
By recreating ‘near normal’ Valsalva units, their new aortic two-stage prosthesis would promise a better expected longevity of stented bio-prosthesis in comparison to its use with classical cylinder tube. This would be a reliable alternative to root replacement by means of stentless bio-prosthesis in that it avoids the occurrence of calcifications around the coronary ostial reimplantation sites.
Similarly, the convexity of their prosthesis permits a lesser dissection and mobilisation of coronary trunks which offers a better surgical perspective rather than indirect ostia reimplantation techniques when dissection and mobilisation of the trunks seem to be hazardous [2].
However, I would like to point out some concerns about their conclusions. The prompting effect of aortic root on coronary flow is reflected directly in the subsequent antegrade flow. As the systolic flow of LAD is also affected by systolic retrograde flow from its collaterals, the mid portion of LAD may not be an appropriate site for the analysis of the systolic antegrade flow issued from coronary ostium [3]. In this sense, the mean follow-up in group C is significantly longer than in other two groups. This later factor could mean a greater amount of myocardial recovery and subsequently a lesser impediment to systolic antegrade flow by retrograde collateral flow.
Secondly, the systolic velocity is closely related to epicardial network capacitance which is subject to specific histopathological changes determined by underlying physiopathological settings [4]. As the patients' subsets are not matched in this regard, the weight of such confounding factors cannot be ruled out.
Third, an isolated augmentation in systolic fraction under maximal hyperemia (groups B and C) and without tachycardia which is not accompanied by any significant difference in percent augmentation of CBF and or in coronary reserve (in comparison with group A) does not lend strong support for prompting effects of pseudo-sinus on CBF, if present [5].
Finally, the authors have not reported the details of time integral velocity of systolic and diastolic fractions at baseline and after maximal hyperemia. Inasmuch, they have attributed the reduction of diastolic/systolic integral ratio under maximal hyperemia to diminution of diastolic components (15–20% for groups B and C) while they consider as well the same reduction in diastolic/systolic integral ratio secondary to augmentation of systolic components (groups B and C), thereby the analysis of reported data is somehow clouded.
In conclusion, I would recommend the use of this new vascular prosthesis in regard to its aforementioned mechanical advantages while awaiting a structured experimental investigation which may back up my choice to good advantage by demonstrating its speculated prompting effects on CBF.
References
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