I often prefer a direct stenting technique in both elective and primary PCI. However, I think the procedure is easier if one or two simple rules are observed.
-
Either the lesion or the route to the lesion needs to be free of too much calcium. Obviously the chances of success will markedly reduce with both age and a distal position of the target lesion/lesions, and will always be more difficult in circumflex territories.
-
Anticipate the need for maximum guiding catheter support and routinely choose the one in which you have most confidence. For the LAD, I like a slightly under curved Judkins, so that if required I can use it as a “reversed Amplatz” technique for deep support. I usually start with a 4cm curve Judkins, and I am not afraid to “deep throat”. For the right again I start with a 4cm curve non sideholed Judkins catheter. I always like to use 6 French and, as the distal segment is made a little softer and more controllable by a longer period in the circulation, I do not rush to a lesion, unless of course clinical or diary circumstances demand!
-
Always use a marker wire. Any marker will do, but I like the ATW marker as I seem to have luck with it. In fact I use an ATW wire at all times but again, a bit like catheter selection, personal preference, often based on nothing really objective, is the driver. The marker wire is used to determine the length and diameter of the stent. Be careful not to position the wire too distally in the circulation so that it passes the measurement point.
-
Stent Choice - Endeavour or Taxus on the Liberty platform are my preferences, acknowledging that drug elution is not always agreed in primary angioplasty. This choice may be more driven by size availability, which in our labs favours these systems. Lesions of 4mm diameter, vessels with acute coronary syndromes and discreet lesions could be grounds for using bare metal systems.
a) Stent Diameter – Whatever the stent, make sure it is not undersized. However, there can be variations depending upon whether there is a primary or elective setting. In a primary setting, with an unstable vessel wall, I prefer a slightly oversized stent inflated softly, by which I mean 7 atmospheres. It is very important when using “low” atmosphere inflation to have the stent fully opposed.
In elective procedures, where there could conceivably be more stability to the vessel wall but perhaps harder lesions, I prefer a balloon vessel ratio of 1. Considerably higher pressures can be used if required to achieve angiographic optimal position of the stent. I am not a big IVUS fan, having been brought up on 35 years of using angiographic appearances to judge complete aposition!
b) Stent Length – As in all techniques, try not to bury the stent margins in plaque. For me this is easier with the marker wire, since the length of the stent does not have to be judged by predilatation of the balloon.
-
Inflations – When inflating with high or low pressure protocols, I prefer to avoid even numbers (for no reasons at all than habit and superstition); not be unconcerned about exceeding stated burst pressures but to continue to higher pressures so that there is absolutely no balloon deformation; and usually to inflate beyond deployment ratings unless there is no deformation in a higher stent to vessel ration balloon choice. I also prefer longer inflation times as there is time delay for the syringe pressure to reach the balloon. I like the idea of “setting” a stent with no angiographic deformation to achieve a stent vessel ratio of more than one either by low or high pressure inflations according to the above clinical circumstances.
-
Post Inflation Protocol – Never remove the balloon after deflation without angiographic check, as there may be need for even higher pressures, perhaps to burst if there is continuing deformity, and particularly in an elective case. Further, although I believe exit dissections are less commonly seen when there is no pre-dilatation, these can occur. There may be a need for softly reshaping the distal edge of the stent if it is landed not as intended in a segment which is angiographically free of disease, but where there is still some plaque. Distal plaque should never be chased.
I am a strong supporter of not causing differential sheer stresses within the stent length. By this I mean that I have to be pushed very hard to post dilate, even in overlaps and bifurcations, but more on this in another issue I believe that differential sheer forces can disturb stent coatings, and I feel intuitively that metal disruption/fatigue is more likely when a whole stent is subjected to uneven segmental pressures.
