Dilation of knitted grafts in the thoracic aorta

I read with great interest the article by Bogaert et al. [1]. The authors emphasize the dilatation of a particular knitted vascular prosthesis (Gelseal) in the upper thoracic aorta after redo surgery for coarctation.

Regarding the operative technique used, I have several questions. Single cross-clamping was used in all patients; there was one paraplegia (6%) and 25% left recurrent nerve damages. Although they describe a historical series with the primary intervention between 1978 and 1985, it is not stated exactly in their paper when the second intervention took place; due to the fact that the patients were followed by MRI and taking into account the interval between the patch angioplasty and the redo repair of 8–17 years later, it certainly must have been after 1986. I wonder why the authors did not use the left heart bypass or deep hypothermic circulatory arrest (DHCA); the latter technique might even provide better organ protection. Since 1986, we routinely use left heart bypass for primary interventions in this aortic region and DHCA for redo cases in which the region of the left subclavian artery containing the left recurrent nerve is more or less hostile. These techniques offer an almost 100% guarantee against spinal cord problems. In other words, the one paraplegic case could have been avoided in my opinion. DHCA allows for careful sparing of the left recurrent nerve and also for repairing the inner curve of the hypoplastic arch in order to enlarge it and to get better postoperative hemodynamic flow patterns.

The authors state that the graft dilatation might be triggered by the untouched hypoplastic arch. In my opinion, the cause of graft dilation has nothing to do with the hypoplastic arch, but it is inherent to the prostetic material used. The curve of graft dilation looks very similar to that of our own investigations [2] proving that knitted grafts dilate, especially in the thorax. The percentage of dilation might even be as high as 35% [3], and we have seen patients with more than 100% expansion over time. So, I differ in opinion that the outcome of this newly inserted tubular graft in this anatomic position is unknown. The outcome of the prosthetic graft will be exactly the same whether it is after primary or secondary intervention, whether it is for coarctation or for aneurysm repair: a knitted graft will dilate and continue to dilate.

I congratulate the authors for stressing again the point that knitted vascular grafts should no longer be used in the thoracic aorta; woven polyester grafts are much more stable.

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