Anomalous Left Circumflex Artery Originating from Right Coronary Artery (RCA) with Wire Knuckle Push of RCA: A Novel Technique for PCI

Coronary artery anomalies (CAA) represent a distinct and diverse group of entities with a reported incidence of approximately 1%, ranging from 0.3% to 5.64%.^1-5 Various normal variations and anomalous coronary arteries have been described in the literature. Any variation with incidence >1% is usually considered as a normal variant and not as an anomaly.^1-4 Anomalous origin of the left circumflex (LCX) with a separate ostium from the right sinus of Valsalva is the most commonly described coronary artery anomaly in the literature, with a reported incidence of 0.41%.⁶ The second most commonly described anomaly is the origin of LCX from the main right coronary artery (RCA) with a reported incidence of 0.37%.^1,5 Anomalous coronary arteries pose considerable challenges and/or technical difficulties for the interventional cardiologist during percutaneous coronary intervention (PCI). Here, we present a case of acute coronary syndrome with a severely diseased anomalous LCX, successfully managed with a novel PCI technique. 

 

 

A 56-year-old male presented with unstable angina pectoris. He had known severe anomalous LCX disease managed medically thus far. Past medical history was also significant for hypertension, hyperlipidemia, and diabetes. Cardiovascular physical examination was unremarkable. An electrocardiogram (EKG) showed sinus bradycardia and diffuse, mild ST segment elevations. An echocardiogram showed normal left ventricular systolic function and no pericardial effusion. Troponin I level was initially normal. The patient was treated with heparin, nitroglycerin, beta-blocker, statin, and aspirin. Coronary angiography showed non-obstructive disease in the left anterior descending artery (LAD); the LCX was not visualized on the left system injection (Figure 1 shows the right anterior oblique [RAO] caudal projection). The RCA was dominant with normal take-off and no obstructive disease noted; however, the LCX was seen coming off the proximal part of RCA, and was noted to be severely and diffusely diseased. The mid LCX had a 95-99% stenosis and distal segments with less severe but also obstructive disease in the proximal portion (Figure 2 is the left anterior oblique [LAO] straight projection). The LCX had a culprit lesion that we decided to stent. A 6 French multipurpose guide catheter (Multipurpose [MP] 2 [Boston Scientific]) was inserted via right femoral artery access. This catheter has a tendency for deep intubation of the RCA (Figure 3). In order to avoid an unfavorable prolapse into the take-off of the LCX on pullback (there is a right angle between the proximal LCX and the guide, thus increasing the risk of LCX guide dissection), a Balance Middleweight (BMW) guide wire (Abbott Vascular) was placed into the distal RCA branch. Its distal end was looped (into a “knuckle”). The wire was pushed forward and in doing so, the guide catheter was pushed in a controllable manner out of the RCA to the level of the LCX take-off. Once at this level, the LCX was wired with another BMW guide wire (Figure 4). The LCX was predilated with a 2.0 x 15 mm balloon and then stented with a Xience Prime 2.75 x 38 mm stent (Abbott Vascular) (distal and mid portions) and 2.75 x 18 mm (proximal) stents at high pressure. The result was satisfactory (Figure 5, Video 1).

 

 

Anomalous origin of the left circumflex with a separate ostium from the right sinus of Valsalva is the most commonly described coronary artery anomaly in the literature, with a reported incidence of 0.41%⁶ and the next common anomaly described is the origin of LCX from main RCA, with a reported incidence of 0.37%,^1,5 as seen in our case. There has been conflicting data on whether coronary artery anomalies are associated with an increased risk of atherosclerosis.^7-9 Certain anomalies also increase the risk of epicardial vessel atherosclerotic disease, if a portion of anomalous artery is inside the myocardium (myocardial bridge) and leading to narrowed vessel during systole.⁸ One study showed a similar risk of atherosclerotic disease in comparison to atherosclerotic risk in the general population,⁷ while another study demonstrated increased atherosclerosis with the presence of a coronary artery anomaly.⁹ The initial presentation of anomalous coronaries varies significantly across a spectrum, from being found incidentally in an asymptomatic patient to being retrospectively discovered in sudden cardiac death on autopsy. Various anatomical features have been associated with sudden cardiac death, including abnormal coursing, acute angle take-off and ostial abnormalities.⁷ Patients often present with angina pectoris or syncope, especially on exercise, and our patient presented with unstable angina. Anomalous coronary arteries may pose a challenge to diagnosis if the vessel is severely diseased or if the possibility of anomalous coronary artery is not considered. 

 

Current guidelines indicate that certain anomalies/presentations are considered high risk and therefore should undergo surgical revascularization with coronary artery bypass graft surgery (CABG). However, our patient’s presentation did not meet criteria for CABG^10,11 and thus we chose to perform PCI in this patient.

 

The selective cannulation of anomalous arteries can be technically challenging and time consuming. Multiple angiographic factors such as ostium configurations, aortic 

root dimensions, and lesion location play a crucial role in the intervention of anomalous arteries. Most available catheters are designed for usual coronary anatomy and the guide catheter might not fit or comply well into an anomalous coronary ostium or system. Since the ostium of the LCX is inside of the RCA, use of a traditional guide for the RCA such as a Judkins right or Amplatz left guide catheter is not feasible for anomalous LCX intervention. If the Jukins right catheter deeply intubates the RCA, the tip of catheter can create an ostial and/or proximal RCA dissection, even a right aortic root dissection. In our case, the MP guide catheter appeared to be an appropriate catheter because of its ability to deeply intubate the RCA without significant damage to the artery. The second challenge was wiring the LCX lesion. The MP catheter tip is coaxial with the RCA without angle; the catheter needed to be pulled back to the LCX ostial level with fine, controllable movements, but it was also difficult to hold the catheter at the LCX ostial level without moving it back and forth while wiring the ostial LCX. Even an MP can disengage from the RCA and lose wire position completely. The knuckle technique provided a solution to this interventional challenge, making it easier and more efficient to wire the LCX. After the MP deeply intubated the RCA just beyond the LCX ostial level, the first BMW was placed into the distal RCA with a loop. By gently pushing this wire forward, the loop in the distal RCA pushed the MP2 outward to reach ostial level of the LCX and helped to stabilize the MP2 in place. The second BMW, with a large wire tip according to the RCA and LCX angle, should allow easy wiring of the anomalous LCX without multiple attempts. We kept the first BMW wire in the distal RCA during the LCX intervention, because it helped to stabilize the MP guide position. Another approach is to simply withdraw the guiding catheter over a non-knuckled guidewire down the RCA just proximal to the LCX ostium; then the second wire can be carefully advanced to the LCX. When withdrawing the guide catheter from the hub, transmission to the tip may be less controllable and the guide may potentially completely disengage from the ostium of the RCA. The knuckled guidewire technique may provide better control of the guide catheter and stabilize the guide movements because of the short distance from the knuckle tip.

 

 

The origin of LCX from the main RCA is a common anomaly. In acute coronary syndromes, the culprit lesion in an anomalous LCX creates an interventional challenge. By wiring the RCA first and using the “push the knuckle” technique, a safe and elegant positioning of the guide catheter at the bifurcation, and further intervention, can be achieved easily and effectively. Our knuckle technique provides an advantage over withdrawing the catheter over a non-knuckled guidewire down the RCA. The knuckle technique also provides increased stability, allowing for finer control from the proximal hub end of the catheter/wire, especially helpful in cases requiring urgent intervention.