except in case of severe enlargement and offering off‐line electronic magnification to study vessel details. These wide fields of view reduce radiation burden, especially if appropriate filtering is used, and allow fitting all the arteries without panning. For 18 cm/7 Fr or less panning is usually required in the RAO cranial and LAO cranial views to image the distal LAD. Smooth slow panning allows the X‐ray generator to adjust automatically to changes in X‐ray attenuation. The lateral view is a good alternative for demonstrating the distal LAD around the apex but can also require controlled movement of the table during the acquisition toward the floor and/or in the direction of the head. The RAO caudal view can include the distal LAD without the requirement for table movement or being affected by diaphragmatic movement.
Circumflex
The circumflex ostium can be clearly seen together with the LMS bifurcation in the LAO caudal view. Occasionally, eccentric ostial lesions not clearly seen in other views can be delineated in the RAO cranial view although steep angulation may be required. The RAO caudal is the most useful diagnostic view for the circumflex and can clearly define lesions in the ostium, proximal, and mid vessel as well as the bifurcations and obtuse marginals. To obtain a working view with improved image quality by eliminating overlap with the diaphragm and reduced X‐ray attenuation, the view can be modified to AP caudal with only 10–15° rightward angulation. RAO or LAO with cranial angulation can be required to view lesions in the distal circumflex when the RAO caudal is suboptimal. If the circumflex is dominant, the LAO cranial or AP cranial views may open up the distal bifurcation and elongate the posterior descending artery. Optimal angiographic views for specific segments in the circumflex are shown in Figure 4.8a.
Right coronary artery
Views that reliably demonstrate the full length of each coronary segment while minimizing foreshortening and overlap for the RCA are shown in Figure 4.7b. Usually, the only two views required to demonstrate lesions in the proximal, mid, and distal RCA are LAO and RAO, because of the absence of side branches in these segments. Ostial lesions in the RCA are often detected in LAO but can be significantly foreshortened in this view. If stent placement is being considered, finding the least foreshortened segment can facilitate accurate positioning at ostium. The ostial segment and proximal RCA often lay perpendicular to the X‐ray beam in the AP cranial and LAO caudal views, despite variation in the origin of the RCA toward anterior or posterior. The lateral view with cranial angulation can identify occasional highly eccentric ostial lesions not clearly seen in other views. The lateral view can also help to better delineate lesions in the mid RCA or when right ventricular branches overlap the main vessel.
The distal RCA, PDA, and posterior left ventricular (PLV) branches lie posterior to the heart and require cranial angulation (in LAO) or caudal angulation (in RAO or AP) to be visualized without overlap. Many operators routinely include a third view, either AP cranial or LAO cranial, in addition to LAO and RAO as standard during diagnostic imaging.
Vein grafts
An operative report describing graft number and insertions, a prior coronary angiogram or a CT coronary angiography is imperative to reduce the chances of missing a graft as well as to reduce fluoroscopy dose and procedure time spent hunting for an unknown number of grafts. An aortogram can be helpful for graft localization, potentially saving time and contrast, but it is not a panacea, because grafts can sometimes be missed completely when the take off is covered by the aorta and flow is slow. The insertions of vein grafts can vary substantially, in particular after redo bypass surgery. A rule of thumb is that the aorto‐ostial insertions of vein grafts to the left coronary system tend to arise lower and more anterior for grafts to an anterior artery (e.g. LAD) and progressively more superior and leftward as the insertion site moves more toward left lateral (e.g. diagonal, intermediate, obtuse marginal, AV circumflex). In the RAO view, left‐sided grafts can be intubated by pointing the catheter toward the right of the screen. Right‐sided grafts can be found in LAO by dragging the catheter pointing to the left of the screen along the ascending aorta starting above the RCA ostium. Selective intubation with the catheter coaxial to the graft origin is essential to optimize visualization of the distal anastomosis and grafted distal native arteries. The catheter tip is often misaligned when there is a vertical origin of a vein graft to the RCA intubated with a JR catheterA more coaxial intubation is allowed by a Multipurpose or right coronary bypass (RCB) catheter for a right‐sided graft and a Multipurpose, Amplatz or left coronary bypass (LCB) for left‐sided grafts. (Figure 4.5) The views are selected according to the native coronary segment where the graft inserts, minimizing overlapping and two perpendicular views are often required.
Figure 4.5 Guiding catheter selection for SVG to right coronary artery: (a1) JR catheter via the left radial and especially the right radial artery are rarely effective in coaxial intubation of vertical grafts for the RCA. (a2) AL1 or 2 catheters via right radial or left radial artery may require more manipulation but are more often successful (a3) Multipurpose catheters are the shape of choice via right radial, left radial artery or also femoral approach. Guiding catheter selection for SVG to circumflex artery: (b1) JR catheter or, (b2) more predictably, AL1 or AL2 catheters are effective in achieving selective engagement of the posterior lower grafts to the LCx or diagonal branches (b3) High and posterior take off can be challenging from both radial arteries and most often requires a large Amplatz guide. Guiding catheter selection for LIMA to LAD (c1) Classic IMA catheter via left radial artery (c2) classic IMA via femoral artery. Steering for selective cannulation can be made problematic by extreme subclavian tortuosities.
A recent multicenter study that included almost 1500 patients with previous CABG undergoing SVG angiography and PCI showed that the radial approach is safe and achieves similar results with overall less number of catheters and trend toward lower contrast volume as compared to the femoral approach; overall, patients undergoing procedures through the radial approach had significantly less bleeding complications. In the majority of these patients a left radial approach was preferred because of the need for concomitant visualization of the left internal mammary artery [3].
Left internal mammary artery grafts
The left internal mammary artery (LIMA) graft is usually prognostically the most important. Selective intubation of the LIMA with demonstration of the entire length of the graft and native vessel including any lesions and collateral supply is the standard. The origin of the left subclavian artery is usually engaged in the AP view. An 0.035‐inch J‐wire is used to lead before the catheter is advanced over it to reduce the risk of trauma to the vessels. If difficulty is encountered with an abnormal aortic arch, severe tortuosity, or stenosis, intubation of the left subclavian may be easier in the LAO view, using non‐selective contrast injections to delineate the anatomy and a JR rather than an internal mammary artery (IMA) catheter can help engaging the left subclavian. If it is possible to insert the catheter over a wire into the subclavian artery, an IMA catheter can be inserted via a 300‐cm J‐wire. A 0.035‐inch steerable polymer jacketed soft J‐wire (Terumo) guide is helpful if extreme tortuosity prevents passage of the standard J‐wire guide. Once the catheter tip is near the ostium of the LIMA, the AP view is most useful for engagement. The JR catheter tip is often too horizontal or too short to engage the ostium of the LIMA; in this case an IMA catheter or the even more acute shorter hook of a Bartorelli‐Cozzi (BC) catheter are the shapes of
