Native Coronary Angiography
Stephen Gimple
Niranjan Seshadri
Robert E. Hobbs
Sorin Brener
The coronary arteries arise from the sinuses of Valsalva. The left main coronary artery arises from the left sinus. After a short course, the left main trunk usually bifurcates into the left anterior descending and left circumflex coronary arteries. In some instances, it may trifurcate, with the ramus intermedius being the intermediate vessel in the trifurcation. The current classification of coronary anatomy is based on the CASS system.
The left anterior descending artery (LAD) follows a course along the anterior interventricular groove to the apex of the heart, supplying blood to the anterior wall, the septum via septal perforators and the anterolateral wall via diagonal branches.
The left circumflex coronary artery (LCX) courses along the left atrioventricular groove supplying the lateral wall of the left ventricle. The branches arising from the left circumflex are called obtuse marginals, with the first branch arising from the atrioventricular circumflex called obtuse marginal 1, the second branch called obtuse marginal 2, and so forth.
The right coronary artery (RCA) arises from the right sinus of Valsalva and travels along the right atrioventricular groove. The first branch that arises from the right coronary artery is the conus branch, which supplies the right ventricular outflow tract. In approximately 50% of the cases, the conus branch has a separate origin. Localizing the conus branch may be important in selected cases because it is often a critical source of collateral circulation to the LAD. Other branches include the artery to the sinus node, which arises from the RCA in 60% of cases; the acute marginal branches, which supply the right ventricle; the artery to the AV node; the diaphragmatic artery; and terminal branches: the posteroventricular branches and the posterior descending artery (PDA) in most cases.
The PDA, which courses in the posterior interventricular groove, determines coronary dominance. In 85% of the cases, the PDA arises from the RCA, making the coronary circulation right dominant. In 7% of the cases, the circulation is codominant, with the posterior interventricular groove being supplied by both the RCA and the LCX. In 8% of the cases, the PDA arises from the left circumflex making it the dominant artery.
Engaging the Coronary Arteries
For diagnostic coronary angiography, we routinely use 4 or 5 Fr. Judkins left and right catheters via the femoral approach. However, the use of the radial approach in appropriately selected patients is increasing and may soon be the standard for diagnostic angiography. Use of smaller caliber 4 or 5 Fr. systems has some advantages. For example, in patients requiring only diagnostic angiography prior to heart valve surgery, use of a 4-Fr. system decreases recovery time and allows faster ambulation after sheath removal (see Chapter 8). In addition, the use of the radial approach also fosters shorter recovery times as well as shorter hospitalization times.
Engaging the Left Coronary System: Assuming that the size of the aorta is within normal limits, a Judkins left 4 (JL4) is routinely used. The catheters are flushed with heparinized saline and advanced over a J-tipped guide wire (“J wire”) through the femoral sheath and to the ascending aorta just above the aortic root. To avoid retrograde dissection of the aorta, catheters are advanced with the J-tipped guide wire protruding beyond the proximal end of the catheter. Once the catheter is just above the sinus of Valsalva, the guide wire is withdrawn and a few drops of blood are allowed to back bleed from the catheter allowing for clearance of debris that may have collected during catheter advancement. The catheter is then connected to the manifold, flushed with saline, and the syringe is loaded with dye. Once an adequate pressure tracing is seen, the catheter is opacified with 1 to 2 cc of contrast dye and is ready for selective engagement.
Using the Judkins technique, not much effort is required to cannulate the ostium of the left main trunk. The catheter is advanced into the aortic root, and in the majority of the patients, it will engage the ostium. The catheter tip should be coaxial with the left main trunk. In cases where the left main trunk is not easily cannulated, a clockwise or a counterclockwise turn may help engage the ostium.
Once the ostium of the left main trunk is engaged, a good pressure waveform should be observed before proceeding with coronary arteriography.
Troubleshooting
The catheter does not back bleed: If the catheter does not back bleed after removing the guidewire, the tip may be apposed to the wall of the aorta. Gently withdraw the catheter, and turn it either clockwise or counterclockwise to free the catheter tip. After discarding a few drops of blood, connect the catheter hub to the manifold and look at the pressure tracing.
No waveform is observed in the pressure tracing: If no waveform is observed in the pressure tracing, the transducer may not be opened to pressure. This may be rectified by manipulating the first of the three-way stopcocks on the manifold or by turning the transducer at the side of the table to the on position.
Catheter is NOT engaged and the waveform is dampened: This may be due to air in the system or the catheter may be partially against the arterial wall. To eliminate air in the system, first gently withdraw a few drops of blood and flush the manifold and catheter with saline, taking care not to reintroduce air in the system. A gentle clockwise or counterclockwise rotation along with pulling back the catheter will move the tip away from the aortic wall. If the dampened waveform persists, it may be due to air in the pressure transducer tubing. Flush the transducer tubing and recheck the pressure. If the problem persists, in rare cases, the catheter itself may have a kink, in which case it needs to be replaced.
Troubleshooting
The aorta is dilated, and it is difficult to engage the left main trunk with the JL4: In the case of a dilated aorta, the curve on the JL4 catheter may be too short to engage the ostium of the left main trunk. Upsizing to a JL5 or even JL6 catheter may help. Additionally, with a dilated aorta there may not be a hinge point for the arm of the catheter to rest. In this case, a counterclockwise (moves the catheter anteriorly) or a clockwise rotation (moves the catheter posteriorly) helps engage the ostium.
The patient is not of average height: The size of the aorta is often proportional to the height of the patient. Some operators start with a JL4 in nearly all patients. Other operators will start with a JL3.5 if the patient is less than 5′4″ tall, or a JL5 if the patient is greater than 6′2″ tall.
The left main trunk has an unusual takeoff: In some cases, the ostium of the left main trunk may have a takeoff in a plane that may be out of the reach of the Judkins catheters (usually a high posterior origin). Switching to an Amplatz system may be helpful. Amplatz catheters are advanced around the aortic arch over a guide wire. The catheter is further advanced until the curve rests in the left sinus of Valsalva with the tip facing the ostium of the left main trunk. Withdrawal and gentle clockwise and/or counterclockwise rotation brings the tip in plane with the coronary ostia. To disengage the Amplatz catheter, it is important to first push it gently forward (brings the tip out of the coronary ostium), and rotate before pulling back, all under fluoroscopic guidance.
Troubleshooting
The catheter is engaged and the waveform is dampened: A dampened pressure waveform (drop in the catheter tip systolic pressure) or a ventricularized pressure waveform (drop in the catheter tip diastolic pressure) usually indicates that the catheter tip is either deep seated, restricting coronary inflow, or the tip is against the wall. It also indicates the possibility of significant left main stenosis. This can be a dangerous situation that needs to be recognized quickly. The catheter tip should be immediately withdrawn from the ostium. The ostium can be re-engaged cautiously. If a small injection of dye reveals significant ostial left main stenosis (another clue may be the absence of dye reflux into the aortic root with the injection), two short cine runs aimed at visualizing distal targets for bypass surgery should promptly be performed, and the catheter then immediately pulled back from the ostium. Care must be taken to avoid multiple engagements of the left main trunk as this can lead to abrupt vessel closure. In cases where significant left main trunk stenosis is suspected, the operator can take nonselective angiograms of the left main trunk by injecting dye with the catheter tip positioned in left sinus. Catheter damping may also be seen in cases of spasm of the left main trunk. In such instances, intracoronary nitroglycerin can be injected (200 μg) and follow-up picture can be taken to document relief of spasm.
Engaging the Right Coronary Artery: Engaging the RCA often requires more skill with catheter manipulation than engaging the left coronary artery. The Judkins right 4 (JR4) catheter is most commonly used. The JR4 is advanced to the right coronary cusp, with the tip facing the left ostium. The catheter is gently pulled back while simultaneously rotating the catheter clockwise to engage the right ostium (the tip of the catheter tends to migrate down toward the sinuses with clockwise rotation). Alternatively, the clockwise rotation may be performed above the plane of the right coronary ostium without pulling back. This will make the catheter tip move down toward the sinus while rotating. The ostium is usually found about 2 cm above the aortic valve. After engaging, the pressure waveform is visualized, and if satisfactory, coronary arteriography may be performed.
Coronary Angiographic Views
Coronary arteriography provides a silhouette of the epicardial coronary arteries. The basic views, posteroanterior (PA), left anterior oblique (LAO), right anterior oblique (RAO) with or without varying degrees of either cranial or caudal angulation, show the coronaries in orthogonal views, while minimizing interference by other structures, such as the spine and the diaphragm. It is important that each segment of coronary is evaluated in two orthogonal views, with care to avoid significant vessel overlap and with visualization of all important side branches.
Troubleshooting
Difficulty engaging the RCA: The ostium may be high and anterior, posterior, or angled upwardly. A 3DR catheter may be used if the JR4 catheter fails to engage the ostium. This catheter is dropped to the aortic valve and gently pulled back without rotating the catheter. For a high and anterior takeoff (frequently seen in transplanted hearts due to rotation of the heart), pulling the catheter further back with a less clockwise turn usually engages the ostium. For a posteriorly directed ostium, further clockwise rotation may be required. For an upwardly directed ostium or dilated ascending aorta, an Amplatz catheter works well. To engage the ostium of the RCA arising from the left sinus of Valsalva, an Amplatz left (AL 1) catheter may be used. Other catheters that may be used include an Amplatz right or a multipurpose catheter.
The pressure waveform is dampened or ventricularized: This usually indicates the catheter tip is either deep seated, restricting coronary inflow; the tip is against the wall; the conus branch is selectively engaged; or there may be spasm or severe disease of the ostium. If the catheter tip is too far in the artery, the catheter is withdrawn gently without disengaging the ostium and a gentle counter clockwise rotation usually stabilizes the catheter. A gentle clockwise or counterclockwise rotation moves the tip away from the ostium. If the conus branch has a separate ostium, then the catheter may need to be slightly repositioned to avoid this branch, as the main RCA ostium is often very close in proximity. If spasm is suspected, a gentle test injection is performed. The catheter is disengaged, gently re-engaged, and intracoronary nitroglycerin or a sublingual nitroglycerin is administered, provided the blood pressure is acceptable and the image remains suspicious for spasm. If there is true ostial narrowing, a quick injection with just enough dye to fill the artery is done and the catheter is removed from the ostium. Failure to promptly remove the catheter from the ostium of the artery, or proceeding with angiography in the presence of a dampened waveform increases the risk of inducing ventricular fibrillation. Ostial spasm usually occurs a few seconds after engaging the artery. This helps differentiate it from a fixed stenosis.
Torque buildup: When a catheter is rotated from outside the sheath, the torque must be transmitted to the catheter tip before it will rotate. This is best accomplished by gently and quickly moving the catheter in and out a few millimeters while rotating. If torque is allowed to build up within the catheter, the tip can suddenly spin, or “helicopter,” which could cause disruption of aortic plaque or potentially even coronary dissection. Torque buildup is often more problematic in patients with very tortuous iliacs and aortas. Placing a longer sheath can often improve rotational control of the catheter.
In the LAO projection, the image intensifier (II) is to the left of the patient. On fluoroscopy, the spine is to the right of the screen in an LAO view. In the RAO projection, the II is to the right of the patient and the spine is on the left of the screen in fluoroscopy. In general, cranial angulation is ideal for visualizing the distal portion of vessels, and caudal angulation is ideal for visualizing the proximal portion of vessels. The commonly used views shown in Table 3-1 represent only a guide and need to be modified for each individual patient.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
