The trick is to avoid testing empirically more to the right or to the left, a more caudal or cranial angular, and check what a multislice computed tomography suggests.
The increase in coronary computed tomography imaging studies—due to guideline recommendations, practicality, and patient comfort—means that we frequently have these data in the cath lab even before conducting a coronary angiography.
In the analysis of such scans, we have traditionally been “blinded” by lesions, but these studies include much more information, if you know where to look. As regards total occlusions, they can help us “imagine” the right way to point the guidewire in the search for vein grafts or coronary arteries with anomalous origin or location, such as a coronary artery originating from the opposite sinus and located in the transverse (Theile) sinus.
In this work, computed tomography helps us find the right projection to treat ostia or bifurcation lesions.
Researchers included 100 consecutive patients who underwent computed tomography coronary angiography for suspected coronary artery disease, and who underwent angioplasty. Computed tomography data were used to define the optimal projection to treat both coronary ostia and the most significant bifurcation lesions.
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The average optimal projection for ostial left main stenting was left anterior oblique (LAO) 37 and cranial (CRA) 22 (95% confidence interval [CI]: LAO 33-40, CRA 19-25), and for ostial right coronary stenting, LAO 79 and CRA 41 (95% CI: LAO 74-84, CRA 37-45).
For the main bifurcation lesions, projections were as follows: left main – LAO 0 and caudal (CAU) 49 (95% CI: right anterior oblique [RAO] 8-LAO 8, CAU 43-54); left anterior descending with first diagonal branch – LAO 11, CRA 71 (95% CI: RAO 6-LAO 27, CRA 66-77); left circumflex bifurcation with first marginal branch – LAO 24 and CAU 33 (95% CI: LAO 15-33, CAU 25-41); posterior descending artery and posterolateral branch – LAO 44, CRA 34 (95% CI: LAO 35-52 and CRA 27-41).
This guideline is good, but it does not address vein graft ostia and “calibration” requires multiple angiography tests, with a consequent contrast excess.
An alternative with some evidence is the Szabo technique (Catheter Cardiovasc Interv. 2008 Nov 15;72(6):823-8. doi: 10.1002/ccd.21723). This technique consists in partially disassembling the stent and passing a tail wire between the struts (one or more, depending on how much of the stent you want to leave crossing the ostium). This second wire will be placed in the aorta, if treating a coronary aortic ostium, or in the main vessel, if treating a bifurcation lesion. Then, the stent must be advanced and mounted over the wire that crosses the vessel you want to treat; the second wire will stop the stent at the ostium, fixing it and leaving one or two struts out.
This technique helps us not to depend on projection: we only need to push the stent until it is fixed in place by the second wire. Of course, many things can happen during the attempt, from wires inadvertently crossing to the stent dismounting.
All help is welcome in the quest to become as precise as possible in stent implantation.
Original Title: Optimal Fluoroscopic Projections of Coronary Ostia and Bifurcations Defined by Computed Tomography Coronary Angiography.
Reference: Viktor Kočka et al. JACC: Cardiovascular Interventions 2020, article in press. DOI: 10.1016/j.jcin.2020.06.042 y presentado simultáneamente en el EuroPCR virtual 2020.
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