Utility of CT angiography for pre-operative evaluation of robotic-assisted minimally invasive mitral valve surgery.

Utility of CT angiography for pre-operative evaluation of robotic-assisted minimally invasive mitral valve surgery. Poster No.: C-2214 Congress: ECR 2014 Type: Educational Exhibit Authors: M. Muthuvelu, R. Suri, T. Foley, P. Young, E. Williamson; Rochester, MN/US Keywords: Arteriosclerosis, Surgery, CT-Angiography, Cardiovascular system DOI: 10.1594/ecr2014/C-2214 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 15

Learning objectives To illustrate the role of gated thoracic and non-gated abdominal and pelvic CT angiography for complete preoperative assessment in patients prior to minimally invasive, robotic-assisted mitral valve surgery (MVS). Background Mitral regurgitation is the second most common valvular disease after aortic stenosis. Early mitral valve repair is the evidence-based care standard for those with severe degenerative mitral valve regurgitation and has been shown to improve long-term patient outcomes in comparison to non-surgical management. Minimally invasive mitral valve surgery using robotic assistance (Figure 1) has been proven to be an effective alternative to conventional sternotomy approach, with both low perioperative mortality and morbidity, and long term survival compared to conventional techniques. Not every patient is a candidate for robotic assisted MVS. Contraindications for a robotic approach include: 1) Extensive coronary artery disease requiring coronary bypass grafting. 2) Severe peripheral vascular disease precluding safe groin cannulation for retrograde arterial perfusion. 3) Prior median sternotomy or right thoracotomy. 4) Patients with severe mitral annular calcification may be excluded due to inability to ascertain the location of calcific deposits due to absence of tactile feedback. At our institution, CTA of the coronary arteries, abdomen and pelvis serves as a "one stop" pre-operative exam to ensure that the patient is an appropriate candidate for the minimally invasive surgical approach using robotic assistance. In this poster, we will review the role of dual source multidetector CT angiography for preoperative evaluation of MVS patients, including scanning protocols and imaging findings. Images for this section: Page 2 of 15

Fig. 1: A) DaVinci robot. B) Minimally invasive mitral valve surgery using robotic assistance Page 3 of 15

Findings and procedure details Methods: 396 consecutive patients referred for repair of degenerative mitral valve disease using robotic assistance from January 2008 to September 2013 were evaluated with pre-operative CTA. The CTA protocol was designed to allow for sequential evaluation of the cardiothoracic and peripheral vasculature (Figure 2). All mitral valve repairs were performed using robotic assistance, employing standard leaflet correction techniques followed by flexible annuloplasty band placement (Figure 3). Transthoracic cross clamp plus antegrade cardioplegia was utilized for myocardial protection in all cases. Technique: All examinations were performed using a dual source, 64-detector row CT scanner (Siemens SOMATOM definition). ECG gated thoracic examination was performed with scan parameters of variable kv (80-120) and mas (150-400) as determined by patient size (using standard technique charts). Pitch was also variable and was auto selected based on the patient's heart rate. Tube rotation time was 0.33 seconds, detector configuration was 64 x 0.6 mm and field of view was set at 25 cm. Non-ECG gated abdomen and pelvis was performed with scan parameters of 120kV and mas as determined by the patient's size, pitch of 0.6 and tube rotation time of 0.33 seconds. Detector configuration was 64 x 0.6 mm. Triphasic contrast injection protocol was employed to opacify both the coronary circulation and the systemic arteries and veins of the abdomen and pelvis. The dose of contrast and injection rate was calculated as per standard protocol. Findings Coronary CTA images were reconstructed using multiplanar, coronary curved, straight centerline, and volume rendered reconstructions performed on an independent workstation (Figure 4). If coronary stenosis >/= 50% was detected on CT coronary angiogram, catheter coronary angiogram was performed for further evaluation (Figure 5 & 6). A 4-Dimensional cardiac image data set was generated to assess valvular structure and cardiac function (Figure 7). This dataset was reformatted in real time using an independent workstation to provide cine reconstructions of cardiac motion. Typical mitral valve findings included anterior leaflet, posterior leaflet and bileaflet prolapse (Figure 8 & 9). Leaflet tip eversion on CT was Page 4 of 15

found to correlate with an unsupported "flail" segment (Figure 10). Mitral annulus calcification was another relatively common finding of potential clinical significance (Figure 11). Mitral valve pathologic findings were confirmed at intraoperative echocardiography, when indicated. Central and peripheral arteries and veins evaluated included the thoracic and abdominal aorta, the inferior vena cava, bilateral common iliac, external iliac, superficial femoral, and proximal common femoral arteries and veins. The presence of venous obstruction or significant aorto-iliac stenosis, aneurysm or dissection (Figure 12 &13) has the potential to alter surgical approach and can be a contraindication to robotic-assisted repair. Images for this section: Fig. 1: A) DaVinci robot. B) Minimally invasive mitral valve surgery using robotic assistance Page 5 of 15

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Fig. 2: Pre-operative CT technique, including retrospective ECG-gated CTA of the chest (blue horizontal lines), followed by contrast-enhanced CT of the abdomen and pelvis (yellow lines). Fig. 4: 53yr old male with severe mitral regurgitation and intermediate risk factors for coronary artery disease. Minimal calcified plaque at the ostium of left circumflex coronary Page 7 of 15

artery, LCx (arrow). No obstructive coronary artery disease. RCA - right coronary artery, LAD- left anterior descending coronary artery Fig. 6: 74y old male with mitral regurgitation. a) moderate stenosis ( 50-70%) in proximal circumflex coronary artery on CT angiogram, but only mild stenosis (<50%) on catheter angiography (b) Page 8 of 15

Fig. 5: 65y old male with degenerative mitral valve disease. Indeterminate proximal left anterior descending artery segment on curved reconstruction of CT angiography ( a and b) due to diffuse calcified and non-calcified plaques, but only 50% stenosis on catheter angiography (c). Fig. 7: The mitral valve, including segments. a) Surgical specimen, b) CT angiography. Anterior leaflet (A1,A2, A3). Posterior leaflet (P1,P2, P3). Ao - aortic root, Cx - circumflex coronary artery, Pa - pulmonary artery, Cs - coronary sinus, arrow - tricuspid valve Page 9 of 15

Fig. 8: Bi-leaflet mitral valve prolapse, severe in P2 segment. A, B short axis, C,D long axis. AL- anterior leaflet, PL- posterior leaflet. A1, A3, P1-3 are mitral valve segments Page 10 of 15

Fig. 9: Posterior mitral leaflet prolapse (arrows). a) short axis thin maximum intensity projection, b) Left ventricular outflow tract thin maximum intensity reconstruction. Fig. 10: a) bi-leaflet prolapse, b) posterior mitral leaflet prolapse, c) posterior mitral leaflet prolapse with flail segment Page 11 of 15

Fig. 11: Caseous mitral annulus calcification in a patient with mitral regurgitation Fig. 12: 54 y old male with incidental finding of left common iliac artery aneurysm on volume rendered and maximum intensity reconstruction of CT angiogram. Right groin cannulation was done for retrograde arterial perfusion for robotic assisted mitral valve surgery. Aneurysm was repaired after mitral valve surgery. Page 12 of 15

Fig. 13: 59 y old male with a short segment right external iliac artery dissection (arrows). Retrograde arterial perfusion was performed through left femoral artery. Fig. 3: Repair of degenerative mitral valve prolapse. a ) Triangular resection, b) Posterior annuloplasty Page 13 of 15

Conclusion Combined ECG-gated thoracic CT angiography and CTA of the abdomen and pelvis provides a comprehensive pre-operative evaluation of patients undergoing minimally invasive robotically assisted mitral valve surgery. This technique provides important information about mitral valve morphology, coronary and major arterial anatomy and pathology, which is helpful in surgical planning. Personal information Manoharan Muthuvelu MD, MSc, MRCP, FRCR Fellow in Cardiac Imaging Division of Radiology, Mayo Clinic, Rochester, Minnesota, USA. Muthuvelu.manoharan@mayo.edu Rakesh Suri MD Division of Cardiothoracic surgery Mayo Clinic, Rochester, Minnesota, USA. Thomas A Foley MD Division of Radiology, Mayo Clinic, Rochester, Minnesota, USA. Philip M Young MD Division of Radiology, Page 14 of 15

Mayo Clinic, Rochester, Minnesota, USA. Eric Williamson MD Division of Radiology, Mayo Clinic, Rochester, Minnesota, USA. ewilliamson@mayo.edu References 1. 2. 3. 4. 5. 6. Bettencourt N, Rocha J, et al. Multislice computed tomography in the exclusion of coronary artery disease in patients with presurgical valve disease. Circ Cardiovasc Imag 2009; 2(4): 306-1 Catalan P, Leta R, et al. Ruling out coronary artery disease with noninvasive coronary multidetector CT angiography before noncoronary cardiovascular surgery. Radiology 2011; 258 (2):426-34 Nardi P, Pellegrino A, et al. Multidetector computed tomographic coronary angiography as an alternative to conventional coronary angiography in noncoronary surgical patients. J Cardiovasc Surg 2011; 52(3): 429-35 Suri RM, Burkhart HM, et al. Robotic mitral valve repair for all categories of leaflet prolapse: improving patient appeal and advancing standard of care. Mayo Clinic Proc 2011; 86(9):838-44 Morris MF, Suri RM, Akhtar NJ, et al. Computed tomography as an alternative to catheter angiography prior to robotic mitral valve repair. Ann Thoracic Surg 2013;95:1354-9 Optimizing outcomes of robotic mitral valve repair for all prolapse anatomy: the Suri-Burkhart technique. Ann Cardiothoracic Surg 2013; 2(6):841-845. Page 15 of 15