Clinical Editor's Corner

Biplane Coronary Angiography: An old dog with new tricks

morton kern, MD Clinical Editor Professor of Medicine Associate Chief Cardiology University of California Irvine Orange, California mortonkern005@hotmail.com
morton kern, MD Clinical Editor Professor of Medicine Associate Chief Cardiology University of California Irvine Orange, California mortonkern005@hotmail.com
This Editor’s Corner is directed at those practicing in labs with biplane angiographic capabilities. For those without biplane imaging, this discussion might be helpful for your next lab. “Two heads are better than one,” the adage goes, and it applies to imaging as well. Simultaneous biplane cineangiography of the heart provides accurate images from two different points of view and is advantageous in providing reduced contrast volumes and radiation exposure when performing a complete coronary arterial tree visualization or ventriculography. Biplane angiography helps to unravel complex coronary or structural cardiac anatomy (see Table 1). The clinical settings in which biplane angiography is most critical occur in the pediatric population and in those patients with renal failure. Biplane is advocated in some adult interventional procedures like complex electrophysiologic mapping or novel structural heart disease implant device placements (e.g., ventricular septal defect [VSD] occluders). Why is biplane angiography relatively uncommon? The value of biplane angiographic information must be balanced against cost and difficulty of use. Many (older, like me) cath lab devotees will recall that the traditional setup for biplane coronary angiography required the patient’s heart to be in the exact center of the two planes (the isocenter) and then the antero-posterior (AP) and lateral planes were angled in orthogonal projections (e.g., left anterior oblique [LAO]-cranial and right anterior oblique [RAO]-caudal. See Figures A and B). This setup often resulted in more difficulties than it solved. Depending on the team, operator frustration increased with the perceived additional set up and procedure time needed to center the patient, and repeat images that were lost when panning in one plane and out of the other. In addition, the potential savings of contrast media and radiation exposure were eliminated if the two orthogonal planes were not perfectly positioned in the isocenter of the patient. However, biplane would be great if the set up and panning was easy, and kept the images from both planes in view. I had not thought this possible — a typical “old dog, old tricks” viewpoint. In the initial era of balloon angioplasty (circa 1980), biplane angiography was recommended to see the path of the balloon quickly in two projections. It was soon realized that with improved equipment and rapid C-arm motion that single-plane angiography could be almost as quick as biplane and had none of the panning problems. Single-plane imaging also improves access to the patient if a problem should arise in the lab. By the mid-to-late 1990’s, biplane angiography had faded into the background, being used principally in specialized centers, pediatric and rare electrophysiology labs, while most percutaneous coronary intervention labs used single-plane systems, saving the additional expense in order to build another single-plane suite. What’s new about biplane coronary angiography now? What is now prompting me to advocate for the return of biplane coronary angiography? In the last two years, after working in two labs equipped with biplane imaging at the University of California-Irvine Medical Center, one of our technologists suggested I change the biplane setup to concordant cranial or caudal imaging views such as cranially angled LAO and RAO projections, then moving both C-arms to caudally angled LAO/RAO projections (see Figure C). In this way, we did not lose angiographic information when panning, since the heart moved in a similar direction, albeit from the opposite side (but not cranial vs. caudal). Contrast usage was halved, the radiation dose reduced, the procedure time shortened and biplane ventriculography became routine again. This was the new trick for an old dog (me and the imaging technique). Is there a real advantage to biplane left ventriculography? With excellent echo imaging, probably not much, but many times, any ventriculographic information is not immediately available in the cath lab. Recall that left ventricular (LV) function is more accurately assessed by biplane ventriculography. Looking back to 1973, Vogel et al1 reported that the ejection fraction with single-plane angiography was underestimated in patients with coronary artery disease and that biplane angiography of the left ventricle would produce superior results. Bilateral orthogonal projections of the ventricle better correlated simultaneous motion of the heart in regions not seen in one plane alone. Caution must be used when analyzing two non-simultaneous views separately, rather than two projections simultaneously. Myocardial contraction is altered by both volume and contractility, and may be confused by changing wall motion secondary to premature ventricular contractions (PVCs). Vogel et al concluded that single-plane RAO cineangiography underestimates the ejection fraction in patients with coronary artery disease and that the study of segmental wall motion simultaneously provides a better assessment of overall LV function. On the other hand, biplane coronary angiography has not been generally considered critical for routine studies, and I agree. But if you have a biplane capability, with a new trick (the novel setup of cranial-cranial), why not improve your procedures, contrast use and information quality? Some initial relearning is needed before overcoming the lab’s reluctance to old biplane imaging. Spend a minute finding true isocenter in two simple steps: 1) Center the heart under the AP tube. 2) Bring in the lateral tube and center the heart by raising or lowering the table. Now you’re ready to position the planes LAO/RAO, then angle both tubes cranially. This can then proceed to moving both tubes to caudal projections (concordance of cranial/caudal angulations). Try this and experience the benefits of biplane angiography. Last year, a testament to reduced radiation dose and contrast usage, and the importance of biplane in patients with potential contrast-induced nephropathy (CIN) was described in a letter from Kane et al from the Mayo Clinic to the editors of the Journal of American College of Cardiology2, in which they documented that biplane angiography was associated with ultra-low contrast volumes and reduce rates of contrast-induced nephropathy in patients with chronic kidney disease undergoing angiography (National Kidney Foundation Stages III-V chronic renal failure). The average contrast volume of 27 mL for all diagnostic imaging was obtained with procedure times of 15+/-9 min with fluoro times of 4+/-3 min. The volume of contrast was directly associated with the incidence of CIN. Volumes were higher in patients with CIN (45+/-18 mL) than those who did not develop CIN (31+/-18 ml, p Does biplane coronary angiography have a specific benefit to delineating stenosis and anatomy? When compared to intravascular ultrasound as the standard for lesion severity, Bourantas et al3 found that by increasing the angle between biplane projections, the correlation between intracoronary ultrasound and mean estimates of stenosis severity improved. Orthogonal biplane angiography was more reliable than single-plane relative to the intravascular ultrasound lesion assessment. However, I still think that 4, 5 or even 10 views of an intermediate stenosis are still a dilemma not solved by more imaging, but rather physiology. In other studies, biplane angiography provided additional information documenting the true path of anomalous coronary arteries beyond single-plane imaging. For example, Wang et al4 used simultaneous biplane coronary and pulmonary angiography to define the course of an anomalous coronary artery originating from the right sinus of Valsalva. The biplane images confidently demonstrated the several potential courses of the anomalous left main (LM) artery (the retroaortic course, intraarterial, and anterior looping or intraseptal courses). The levophase of the ascending aorta also provides a good view of the posterior aortic wall, further assisting in determining the course of the coronary artery. Biplane was helpful to obtain the “Dot and Eye” assessment of the anomalous LM from the right sinus of Valsalva with fewer views required.5 Is there any reason not to use biplane? Not really. For those with biplane systems that are not in routine use, I suggest beginning your experience with the novel concordant C-arm setup described above. This method was unknown to me before and I believe is not widely appreciated now. The benefits of biplane will be easily recognized and perhaps change the practice of angiography in your lab. The old dog of biplane coronary angiography is worth testing with a new trick. To quote the cliché, the proof is in the pudding. Try it and see. Your patients will appreciate it.
References
1. Vogel JH, Cornish D, McFadden RB. Underestimation of ejection fraction with singleplane angiography in coronary artery disease: Role of biplane angiography. Chest 1973 Aug; 64(2): 217-221.
2. Kane GC, Doyle BJ, Lerman A et al. Ultra-low contrast volumes reduce rates of contrast-induced nephropathy in patients with chronic kidney disease undergoing coronary angiography. J Am Coll Cardiol 2008 Jan 1;51(1):89-90.
3. Bourantas CV, Tweddel AC, Papafaklis MI, et al. Comparison of quantitative coronary angiography with intracoronary ultrasound. Can quantitative coronary angiography accurately estimate the severity of a luminal stenosis? Angiology 2008 May;20:1-11.
4. Wang A, Pulsipher MW, Jaggers J, et al. Simultaneous biplane coronary and pulmonary arteriography: A novel technique for defining the course of an anomalous left main coronary artery originating from the right sinus of Valsalva. Cathet Cardiovasc Diagn 1997 Sep;42(1):73-78.
5. Serota H, Barth CW, Seuc CA, et al. Rapid identification of the course of anomalous coronary arteries: The “dot and eye” method. Am J Cardiol 1990;65:891-898.