The article by Gandhi and Rosenberg¹on anomalous left anterior descending (LAD) origin reopens an old wound in this heart of a student of such subjects:understanding of such anomalies cannot be improvised. To this end, we published recently a comprehensive book on the subject,² frustrated by so many "fascinating cases" inadequately discussed in clinical conferences and published reports. In the present case, I would argue that the key issue is coronary course in coronary ectopies. My interpretation is different from that of the authors, that "the LAD…forms a cranial anterior loop as it passes over the free wall of the right ventricular infundibulum." In addition, they said that"close to its origin, the LAD gives rise to the septal artery."¹ The latter observation is indeed a clue to the angiographic understanding of the course of the LAD in this case. The LAD must be coursing inside the septum, if a septal branch arises from it (it cannot come from a pre-pulmonic LAD, located on the free wall of the right ventricle!). I believe that the case is actually one of an ectopic LAD originated from the right sinus, and coursing inside the crista supraventricularis and then passing inside the upper ventricular septum,before re-emerging at the anterior interventricular groove: the intraseptal course. As widely recognized in the literature,and recently reviewed,^2,3 a vessel that crosses from an ectopic origin on the right and goes to the left, while providing as its first branch a septal branch, has always an intraseptal course, never an epicardial prepulmonic one. Figure 2C is consistent with the intraseptal and not the prepulmonic interpretation (that would make a much larger anterior loop).¹ Unfortunately, coronary angiography provides planar and not tridimensional imaging and it fails to identify the anatomic context of the coronary arteries:only computerized axial tomography or magnetic resonance angiography is able to illustrate the details of those relationships,in similar cases, and enable a firm and more obvious diagnosis of course.³ Ascertaining the course of an ectopic coronary is essential, since it correlates with pathophysiological mechanisms,prognosis (eg, the worst prognosisis the one associated with a "between the aorta and pulmonary artery" course ³),and with surgical implications. The Gandhi case, for example, is especially frequent in Tetralogy of Fallot,² and a surgeon will be quite interested in avoiding such an ectopic vessel, running over the infundibulum (which is usually penetrated longitudinally at the time of corrective surgery).The case of intraseptal course implies an intramyocardial location for several centimeters, that may generate(unusually) a myocardial bridge behavior,as best seen after administration of nitroglycerine. Myocardial bridges may produce ischemia, but only in the dependent territory: in this case, the septal and not the lateral or inferolateral areas mentioned in the nuclear imaging.

Paolo Angelini, MD
Texas Heart Institute, Houston, Texas

References

Unlike Gandhi and Rosenberg, believe the septal branch from the proximal portion of this anomaly makes it likely to be lying in a septal course (despite the cranial anterior loop). If this were an anterior course, there would be no other easy path for the septal branch to get through the conal region of the right ventricular outflow tract into the septum. You might try to obtain a computed tomography angiogram of this vessel, although both anomalies are clinically benign. Thanks for a great report, as these are tough to define angiographically.

Stuart T. Higano, MD
Town & Country Cardiovascular Group
St. Louis, Missouri

Figure 1 Anomalous take-off of LAD from the right coronary cusp.

Regarding the imaging case by Gandhi and Rosenberg, I recently had a similar case. A 76-year-old female presented to the emergency department with chest pain after a heated argument. A myocardial perfusion scan showed inferolateral ischemia, so the patient underwent cardiac catheterization. We found a 90% distal posterolateral stenosis unchanged from 9 months prior that was not amenable to percutaneous transluminal coronary angioplasty and an anomalous takeoff of the LAD off the right coronary cusp (Figure 1). Unlike Gandhi and Rosenberg, we did place a pulmonary artery (PA) catheter to determine if the interarterial course ran between the aorta and the PA, since that course can be associated with chest pain and sudden death (Figure 2). The ischemia seen on myocardial perfusion scan in their case is not consistent with the course described, and I do not see how one can be sure of the LAD course without this reference. In my case, due to uncertainty whether the patient's symptoms were related to the chronic posterolateral stenosis or anomalous LAD, a cardiac surgical consultation was requested.

Figure 2 60 degree lateral view of PA and aortic catheters opacifying both the RCA (anteriorly) and anomalous LAD (running posteriorly interarterially between the pulmonary artery and aorta).View larger sized image.

The patient left the hospital against medical advice, however, so no revascularization has been done at this point.

Nolan Mayer, PharmD, MD
Ventura Cardiology
Ventura, California

Gandhi and Rosenberg conclude that the LAD arising from the right sinus of valsalva has an anterior course across the free wall of the right ventricle. The pictures clearly show a large septal perforator arising from the midportion of the horizontal segment of the vessel. This is pathognomonic for the septal course of this vessel. In the left anterior oblique view, the course is horizontal to concave downward, and not concave upward as one would see with the course across the right ventricular outflow tract. A PA catheter would only have helped if a lateral view had been done to show the course did not go anterior to the catheter. The best way to document the exact course of this vessel is with computed tomography (CT) angiography of the coronary arteries, with at least a 40-slice and preferably 60-slice scanner to get the best images. Three-dimensional reconstruction can clearly document the origin and path of the vessel in relation to the heart and great vessels with no questions left unanswered. I agree with their conclusion that the anomaly does not explain the patient's symptoms or abnormal stress test. The treatment is the same—a benign anomaly not requiring intervention.

Marshall H. Crenshaw, MD
Vanderbilt Heart Institute
Nashville, Tennessee

In Reply

We appreciate the observations and comments of the respondents. While we respect their opinions regarding the intramyocardial route taken by the anomalous LAD vessel, the motion picture cine-angiograms of our patient taken in 2 views suggest that the LAD passes anteriorly to the pulmonary artery. Obviously, we cannot definitively state that. Placing a concurrent pulmonary artery catheter for perspective or conducting CT angiography would help our understanding of the LAD routing. In an effort to determine the routing, we attempted CT angiograpy in this patient at no expense to him. During the study, however, the IV infiltrated, which left the patient understandably upset. He refused to proceed with any further attempts at IV access, ending the test and refusing to return. So, our ability to definitively answer the questions posed eluded us. Should the patient acquiesce, we shall provide follow up.

Michael Rosenberg, MD
Hetal Gandhi, MD
Advocate Lutheran General Hospital
Park Ridge, Illinois