Since the advent of minimally invasive cardiac surgery, the right

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1 Minimally invasive technology for mitral valve surgery via left thoracotomy: Experience with forty cases Paul C. Saunders, MD Eugene A. Grossi, MD Ram Sharony, MD Charles F. Schwartz, MD Greg H. Ribakove, MD Alfred T. Culliford, MD Julie Delianides, MSN F. Gregory Baumann, PhD Aubrey C. Galloway, MD Stephen B. Colvin, MD From the Department of Surgery, Division of Cardiothoracic Surgery, New York University School of Medicine, New York, NY. Supported in part by the Foundation for Research in Cardiac Surgery and Cardiovascular Biology. Read at the Twenty-ninth Annual Meeting of The Western Thoracic Surgical Association, Carlsbad, Calif, June 18-21, Received for publication June 16, 2003; revisions requested Aug 11, 2003; revisions received Aug 13, 2003; accepted for publication Aug 25, Address for reprints: Eugene A. Grossi, MD, NYU Medical Center, Suite 9-V, 530 First Ave, New York, NY ( J Thorac Cardiovasc Surg 2004;127: /$30.00 Copyright 2004 by The American Association for Thoracic Surgery doi: /j.jtcvs Background: Recent evolution of minimally invasive technology has expanded the application of the right thoracotomy approach for mitral valve surgery. These same technological advances have also made the left posterior minithoracotomy approach attractive in complex mitral procedures. Methods: From 1996 to 2003, 921 isolated mitral valve procedures were performed without sternotomy; 40 (4.3%) of these were performed via left posterior minithoracotomy. In the left posterior minithoracotomy group, ages ranged from 18 to 84 years; 36 patients had had previous cardiac surgery (9 on 2 occasions). Other factors precluding right thoracotomy included mastectomy/radiation and pectus excavatum. Results: Arterial perfusion was via femoral artery (n 26) or descending aorta (n 14); long femoral venous cannulas with vacuum-assisted drainage were used in 39 procedures. Two patients had direct aortic crossclamping, 18 had hypothermic fibrillation, and 20 had balloon endoaortic occlusion. The mean crossclamp and bypass times were 81.9 and minutes, respectively. Hospital mortality was 5.0% (2/40); both deaths occurred in octogenarians. There were no injuries to bypass grafts or conversions to sternotomy. Complications included perioperative stroke (2/40; 5.0%), bleeding (2/40; 5.0%), and respiratory failure (1/40; 2.5%); 28 patients (70%) had no postoperative complications. There was no incidence of perioperative myocardial infarction, renal failure, sepsis, or wound infection. The median length of stay was 7 days. Conclusions: Advances in minimally invasive cardiac surgery technology are readily adaptable to a left-sided minithoracotomy approach to the mitral valve. The left posterior minithoracotomy approach is a valuable option in complicated reoperative mitral procedures with acceptable perioperative morbidity and mortality. Since the advent of minimally invasive cardiac surgery, the right thoracotomy approach has become widely accepted for mitral valve procedures. 1-4 The combination of safe cannulation techniques and the excellent exposure attainable from the right chest has made minimally invasive mitral valve surgery an increasingly attractive option. Minimally invasive mitral surgery has been associated with mortality rates of 1.2% to 5.8%, along with less morbidity and a shorter length of stay compared with the conventional sternotomy approach. 1,2 Additionally, avoid The Journal of Thoracic and Cardiovascular Surgery April 2004

2 Cardiopulmonary Support and Physiology TABLE 1. Patient clinical characteristics (n 40) TABLE 2. Previous cardiac procedures Characteristic Variable Age, (y) (mean SD) Age 80 y 3 (7.5%) Valve pathology Mitral regurgitation 25 (62.5%) Mitral stenosis 2 (5%) Mitral stenosis and mitral regurgitation 6 (15%) Prosthetic valve dysfunction 5 (12.5%) Endocarditis 7 (17.5%) Previous right MRM/RT 3 (7.5%) Pectus excavatum 1 (2.5%) Urgent or emergency operation 20 (50%) Comorbidities CHF 12 (30%) COPD 3 (7.5%) Peripheral vascular disease 3 (7.5%) Previous MI 14 (35%) Diabetes 1 (2.5%) Preoperative stroke or TIA 1 (2.5%) Renal disease 0 MRM/RT, Modified radical mastectomy/radiation therapy; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; MI, myocardial infarction; TIA, transient ischemic attack. ing traditional sternotomy is often associated with enhanced recovery 5,6 and better patient satisfaction. 7 For some patients, however, a right thoracotomy approach is relatively contraindicated. Most often this is because of a previous cardiac or thoracic operation, but prior right-sided mastectomy with chest wall radiation may also preclude a right-sided approach. In such cases, minimally invasive nonsternotomy mitral valve procedures are still possible by using a left posterior minithoracotomy (LPMT). The left-sided approach also offers some unique advantages, including a wider angle of vision and a shorter distance for the surgeon to the mitral valve. 8 Recent reports have shown the left thoracotomy approach for mitral valve surgery to be safe, although the numbers of patients in these studies have been small We examined our recent institutional experience with LPMT mitral surgery and its evolution with minimally invasive technology. Patients with a prior cardiac procedure 36 Patients with 1 prior cardiac procedure 9 Mean length to reoperation, mo (mean SEM) Prior procedures performed (n 51) Mitral valve replacement 12 Mitral valve repair 20 Mitral valve commisurotomy 7 Aortic valve replacement 8 CABG 4 Prior approaches used (n 36) Right thoracotomy 17 Median sternotomy 15 Right thoracotomy and median sternotomy 4 CABG, Coronary artery bypass grafting. Methods Patient Clinical Characteristics From 1996 to 2003, 921 mitral valve procedures were performed without sternotomy; 40 (4.3%) of these were performed via LPMT. Patient clinical characteristics are summarized in Table 1. The mean age within the LPMT group was 56.5 years (range, years). Thirty-six patients had undergone previous cardiac operations, 7 had undergone 2 prior operations, and 2 patients had undergone 3 or more prior operations; the mean time from the last operation was 44.2 months. on prior cardiac operations are included in Table 2. Twenty-one patients had undergone a previous right thoracotomy. Other factors that precluded right thoracotomy included mastectomy/radiation (n 3) and pectus excavatum (n 1). Mitral valve pathology in this group included mitral insufficiency in 25 patients (62.5%), mitral stenosis in 2 patients (5%), and prosthetic valve dysfunction in 5 patients (12.5%). Endocarditis was present in 7 patients (17.5%). Surgical Approach Mitral valve procedures were performed with the patient in right lateral decubitus position and with single-lung ventilation techniques. Transesophageal echocardiography (TEE) was performed routinely in all cases. A left posterolateral minithoracotomy incision (approximately 6-8 cm) was made in the fourth, fifth, or sixth intercostal space, and the lung was retracted inferiorly to expose the heart. Figure 1 shows the incision and typical exposure of the descending aorta for direct cannulation. The pericardium was opened posterior to the phrenic nerve and retracted with retention sutures, and the left atrium was opened along the base of the left atrial appendage. Intra-atrial retractors were positioned by using a self-retaining retractor, providing exposure of the mitral valve (Figure 2). Standard mitral repair and replacement techniques were used, and the operative field was flooded with CO 2. After the mitral procedure, the left atrium was closed in 2 layers with 3-0 Prolene sutures (Ethicon, Inc, Somerville, NJ). Deairing was achieved through a transvalvular vent placed through the atriotomy and optionally via a needle placed in the left ventricular apex. Valvular function, myocardial performance, and intracardiac deairing were monitored with TEE. Perfusion Technique Either femoral or direct descending aortic arterial cannulation was used; vacuum-assisted venous drainage was used routinely. When both femoral arterial and venous cannulation were used, a short (approximately 3 cm) transverse left groin incision allowed exposure of the left femoral artery and vein. In these patients, a Heartport arterial cannula (CardioVations; Ethicon) was used, and a 22F long venous cannula (CardioVations) was placed through an anterior pursestring in the femoral vein by using the Seldinger The Journal of Thoracic and Cardiovascular Surgery Volume 127, Number

3 Figure 1. Left posterior minithoracotomy with direct descending aortic cannulation. Figure 2. Surgeon s view of the left atrial exposure. Note that the mitral valve orientation is upside down, with the posterior annulus anterior, as compared with the orientation seen with the sternotomy and right thoracotomy approaches. technique. TEE guidance was used to verify arterial and venous guidewires and position the endoclamp and distal tip of the venous cannula. 12 In those patients in whom central aortic cannulation was used, the descending aorta was cannulated directly, and a long venous cannula was percutaneously placed through the left femoral vein. Myocardial Protection Myocardial protection strategies included either aortic occlusion with retrograde cardioplegia or perfused cold fibrillation (22 C- 25 C). When endoaortic balloon clamp technology was used, cardioplegia was delivered either retrograde via a transjugular coronary sinus catheter or antegrade via the endoclamp catheter The Journal of Thoracic and Cardiovascular Surgery April 2004

4 Cardiopulmonary Support and Physiology TABLE 3. Operative techniques (n 40) Variable TABLE 4. Postoperative morbidity and mortality (n 40) Variable Procedures performed Mitral replacement 30 (75%) Mitral repair 5 (12.5%) Repair of paravalvular leak 5 (12.5%) Surgical approach Left posterior minithoracotomy 40/40 Converted to median sternotomy 0 CO 2 used 23 (57.5%) Interspace used Fourth 9 (22.5%) Fifth 11 (27.5%) Sixth 20 (50%) Perfusion Descending aortic cannulation 14 (35%) Femoral arterial cannulation 26 (65%) Femoral venous cannulation 40 (100%) Myocardial protection Hypothermic fibrillation 18 (45%) Direct ascending aortic crossclamp 2 (5%) Endoaortic balloon clamp 20 (50%) Antegrade cardioplegia 13/22 (59%) Retrograde cardioplegia via 9/22 (41%) percutaneous transjugular coronary sinus catheter Collection All data were prospectively collected by trained nurse clinicians and entered into an institutional database. The database conforms to the definitions used by the New York State Cardiac Surgery Reporting System, an audited data-collection instrument used to record and analyze all cardiac operations performed in New York. Follow-up survival was ascertained from the Social Security Death Index. were retrospectively analyzed with SPSS statistical software (version 11; SPSS, Inc, Chicago, Ill). Results are expressed as the mean SD unless otherwise indicated. Results A summary of operative techniques is found in Table 3. Half of the operations (20/40) were performed through the sixth intercostal space; there were no conversions to sternotomy. Femoral arterial cannulation was used in 65% (26/40) of patients, and descending aortic cannulation was used in the remainder. Femoral venous cannulation was used in all 40 patients. In the first operation performed (without vacuum assistance), femoral venous drainage was augmented with an additional pulmonary artery cannula. Endoaortic balloon occlusion was used in 50% (20/40), and retrograde cardioplegia was given via transjugular coronary sinus catheter in 9 of these (45%). Two early patients had direct aortic clamping. Cold perfusion and fibrillation were used in 18 patients. The mean bypass time was minutes, and the mean crossclamp time (when used; n 22) was minutes. Hospital death 2 (5%) Median ventilation time (h) 10.5 Median total hospital stay (d) 7 Complication free 28 (70%) Complications CVA 3 (7.5%) GI complication 1 (2.5%) Respiratory failure 1 (2.5%) Reoperation for bleeding 2 (5%) Aortic dissection 0 Transmural MI 0 Deep chest wound infection 0 New renal failure 0 Sepsis 0 CVA, Cerebrovascular accident; GI, gastrointestinal; MI, myocardial infarction. In the 15 operations performed since 2001, descending aortic cannulation was used in 87% (13/15), and similarly 87% (13/15) were performed with hypothermic fibrillation. All 15 of these operations used CO 2 in the operative field, and the mean bypass time among this group was 27 minutes shorter than before 2001 ( minutes vs minutes; P.006). Hospital mortality occurred in 2 patients (5%), both octogenarians. One death occurred after an intraoperative posterior ventricular wall rupture in a patient who had undergone previous aortic valve replacement and coronary artery bypass grafting; the other death was associated with a perioperative stroke. Among the 36 patients undergoing reoperative operations, the mortality was 2.8% (1/36). With 95% follow-up, there has been 1 additional postoperative death, which took place 1 year after surgery. Postoperative morbidity is listed in Table 4. Postoperative stroke occurred in 7.5% (3/40); 2 strokes occurred perioperatively, and 1 occurred 1 week after surgery. Two patients underwent reoperation for bleeding. There were no reported instances of exposure injuries to cardiac structures or previous bypass grafts, aortic dissections, or deep chest wound infections. In 28 (70%) of 40 patients, there were no major complications. The median hospital length of stay was 7.0 days. Discussion This experience represents a large contemporary series of mitral valve operations with a left thoracotomy approach. The left-sided approach has existed for cardiac procedures since 1910, when Alexis Carrel 13 proposed it for a coronary artery bypass from the thoracic aorta. Some of the earliest mitral valve interventions were also performed with this approach; in the 1960s, mitral valvuloplasties were commonly approached from the left side. 14,15 However, as median sternotomy became the standard approach for cardiac operations, the left thoracotomy fell out of favor. 16 The Journal of Thoracic and Cardiovascular Surgery Volume 127, Number

5 The 1990s saw an explosion of minimally invasive techniques in cardiac operations, fueled by new technology and driven by the desire for shorter hospital stays and improved patient satisfaction. Minimally invasive approaches for both coronary artery bypass and valve surgery became widely performed at many centers around the world, 7,17,18 and, by using port access technology, mitral valve surgery via right thoracotomy has gained popularity. 4,19,20 At our institution and others, the approach of choice to the mitral valve is the right anterior minithoracotomy approach. 21 The potential of minimally invasive approaches for reoperative mitral valve surgery has been explored as well. 22,23 Avoidance of reoperative sternotomy has allowed for shorter hospital stays, earlier return to work, and fewer transfusions, with morbidity and mortality similar to those of sternotomy. 24 The left thoracotomy approach has been advocated for reoperative coronary artery bypass graft by a number of centers Grosner and colleagues 28 and Lajos and associates 29 have reported a large series of 90 left thoracotomy coronary artery bypass graft patients followed up over 10 years; they cite the advantages of safer exposure in the setting of patent bypass grafts with similar morbidity and mortality. Using left thoracotomy approaches, Hughes and colleagues 11 reported a case of combined transmyocardial revascularization and mitral valve replacement, and Pratt and colleagues 9 described a mitral replacement in a patient who had previously undergone esophagogastrectomy with a substernal gastric conduit. Combined coronary artery bypass graft and mitral procedures using a left-sided approach have been reported. 30 Van Nooten and colleagues 10 reported 10 cases of reoperative mitral valve procedures that used a left thoracotomy, peripheral cannulation, and an endoclamp. Repossini and colleagues 8 reported on 11 patients who underwent mitral valve operations with left thoracotomy, all via femoral cannulation with direct aortic crossclamping. However, this series contained only 1 patient undergoing reoperation, which, in our experience, makes anatomic dissection of the aorta for direct clamping more adventurous. In our series of 40 patients, the minimally invasive technique has evolved since its initial use in In the early experience, all cannulation was performed via the femoral vessels, most cases were performed with endoaortic balloon clamps, and transjugular coronary sinus catheters were frequently used for the administration of retrograde cardioplegia. In our more recent experience, most cases have been performed more simply by using hypothermic fibrillation and direct aortic cannulation. With central aortic cannulation, the issues of obstructive peripheral vascular disease, small femoral arterial size (particularly in women), and possible groin complications have been avoided. 31 With the routine use of vacuum-assisted drainage, long venous cannulation achieves excellent drainage while minimizing the risk of gaseous microemboli. 32 Performing operations under hypothermic fibrillation avoids the use of the balloon endoclamp, 33 which can be more difficult to correct in the right lateral decubitus position without direct access to the ascending aorta. However, the presence of moderate aortic insufficiency remains an indication for the endoclamp technique. Self-retaining intra-atrial retractors, which are routinely used for all minimally invasive mitral procedures, allow for optimal exposure through a small incision. The evolution of this technique has been driven by increased experience with less-invasive strategies and greater comfort with the technology used. In its current form, the left thoracotomy approach is simpler and more adaptable to each individual patient than in its early phases. As a result, the mean cardiopulmonary bypass time has decreased by approximately 30 minutes since This series of patients included 36 patients undergoing reoperative mitral valve operations, 9 of whom had undergone multiple previous procedures. Our experience has shown this approach to be safe and reproducible, with acceptable morbidity and mortality in this high-risk subset of patients, and, significantly, there were no exposure injuries to cardiac structures or bypass grafts. Because the number of reoperative valve procedures continues to increase, safe approaches for reoperative valve operations are increasingly important. As minimally invasive cardiac surgery begins to involve more endoscopic and robotic technology, the left thoracotomy approach may also have specific advantages of its own. By allowing access to the descending aorta for placement of proximal anastomoses, a left-sided approach may facilitate combined mitral and coronary procedures by using endoscopic or robotic techniques. 34 There are some disadvantages inherent in a left thoracotomy, however, most notably the poor access to the ascending aorta for direct crossclamping, especially in the reoperative setting. Also, the orientation of the mitral valve from this exposure is such that it is inverted compared with that achieved from the right side. Conclusion Advances in minimally invasive cardiac surgery technology are readily adaptable to a left-sided minithoracotomy approach to the mitral valve. LPMT is a valuable option in complicated reoperative mitral valve procedures, with acceptable perioperative morbidity and mortality. References 1. Grossi EA, Galloway AC, LaPietra A, Ribakove GH, Ursomanno P, Delianides J, et al. Minimally invasive mitral valve surgery: a 6-year experience with 714 patients. Ann Thorac Surg. 2002;74:660-3; discussion Glower DD, Landolfo KP, Clements F, Debruijn NP, Stafford-Smith M, Smith PK, et al. Mitral valve operation via Port Access versus median sternotomy. Eur J Cardiothorac Surg. 1998;14(suppl 1): S Loulmet DF, Carpentier A, Cho PW, Berrebi A, d Attellis N, Austin 1030 The Journal of Thoracic and Cardiovascular Surgery April 2004

6 Cardiopulmonary Support and Physiology CB, et al. Less invasive techniques for mitral valve surgery. J Thorac Cardiovasc Surg. 1998;115: Mishra YK, Malhotra R, Mehta Y, Sharma KK, Kasliwal RR, Trehan N. Minimally invasive mitral valve surgery through right anterolateral minithoracotomy. Ann Thorac Surg. 1999;68: Walther T, Falk V, Metz S, Diegeler A, Battellini R, Autschbach R, et al. Pain and quality of life after minimally invasive versus conventional cardiac surgery. Ann Thorac Surg. 1999;67: Grossi EA, Zakow PK, Ribakove G, Kallenbach K, Ursomanno P, Gradek CE, et al. Comparison of post-operative pain, stress response, and quality of life in port access vs. standard sternotomy coronary bypass patients. Eur J Cardiothorac Surg. 1999;16: Cohn LH, Adams DH, Couper GS, Bichell DP, Rosborough DM, Sears SP, et al. Minimally invasive cardiac valve surgery improves patient satisfaction while reducing costs of cardiac valve replacement and repair. Ann Surg. 1997;226:421-6; discussion Repossini A, Kotelnikov IN, Parenzan L, Arena V. Left-side approach to the mitral valve. J Heart Valve Dis. 2001;10: Pratt JW, Williams TE, Michler RE, Brown DA. Current indications for left thoracotomy in coronary revascularization and valvular procedures. Ann Thorac Surg. 2000;70: Van Nooten G, Van Belleghem Y, Van Overbeke H, Caes F, Francois K, De Pauw M, et al. Redo mitral surgery using the Estech endoclamp. Heart Surg Forum. 2001;4: Hughes GC, Donovan CL, Lowe JE, Landolfo KP. Combined TMR and mitral valve replacement via left thoracotomy. Ann Thorac Surg. 1998;65: Schulze CJ, Wildhirt SM, Boehm DH, Weigand C, Kornberg A, Reichenspurner H, et al. Continuous transesophageal echocardiographic (TEE) monitoring during port-access cardiac surgery. Heart Surg Forum. 1999;2: Carrel A. On the experimental surgery of the thoracic aorta and the heart. Ann Surg. 1910;52: Clowes GHA, Neville WE, Sancetta SM. Results of open surgical correction of mitral valvular insufficiency and description of technique for approach from left side. Surgery. 1962;51: Austen WG, Wooler GH. Surgical treatment of mitral stenosis by the transventricular approach with a mechanical dilator. N Engl J Med. 1960;263: Balasundaram SG, Duran C. Surgical approaches to the mitral valve. J Card Surg. 1990;5: Grossi EA, Galloway AC, Ribakove GH, Buttenheim PM, Esposito R, Baumann FG, et al. Minimally invasive port access surgery reduces operative morbidity for valve replacement in the elderly. Heart Surg Forum. 1999;2: Gillinov AM, Banbury MK, Cosgrove DM. Hemisternotomy approach for aortic and mitral valve surgery. J Card Surg. 2000;15: Mohr FW, Falk V, Diegeler A, Walther T, van Son JA, Autschbach R. Minimally invasive port-access mitral valve surgery. J Thorac Cardiovasc Surg. 1998;115:567-74; discussion Fann JI, Pompili MF, Burdon TA, Stevens JH, St Goar FG, Reitz BA. Minimally invasive mitral valve surgery. Semin Thorac Cardiovasc Surg. 1997;9: Onnasch JF, Schneider F, Falk V, Mierzwa M, Bucerius J, Mohr FW. Five years of less invasive mitral valve surgery: from experimental to routine approach. Heart Surg Forum. 2002;5: Onnasch JF, Schneider F, Falk V, Walther T, Gummert J, Mohr FW. Minimally invasive approach for redo mitral valve surgery: a true benefit for the patient. J Card Surg. 2002;17: Byrne JG, Karavas AN, Adams DH, Aklog L, Aranki SF, Filsoufi F, et al. The preferred approach for mitral valve surgery after CABG: right thoracotomy, hypothermia and avoidance of LIMA-LAD graft. J Heart Valve Dis. 2001;10: Grossi EA, LaPietra A, Bizekis C, Ribakove G, Galloway AC, Colvin SB. Minimal access reoperative mitral and aortic valve surgery. Curr Cardiol Rep. 2000;2: Ungerleider RM, Mills NL, Wechsler AS. Left thoracotomy for reoperative coronary artery bypass procedures. Ann Thorac Surg. 1985;40: Byrne JG, Aklog L, Adams DH, Cohn LH, Aranki SF. Reoperative CABG using left thoracotomy: a tailored strategy. Ann Thorac Surg. 2001;71: Suma H, Kigawa I, Horii T, Tanaka J, Fukuda S, Wanibuchi Y. Coronary artery reoperation through the left thoracotomy with hypothermic circulatory arrest. Ann Thorac Surg. 1995;60: Grosner G, Lajos TZ, Schimert G, Bergsland J. Left thoracotomy reoperation for coronary artery disease. J Card Surg. 1990;5: Lajos TZ, Akhter M, Bergsland J, Grosner G, Lewin AN, Salerno TA, et al. Limited access left thoracotomy for reoperative coronary artery disease: on or off pump. J Card Surg. 2000;15: Tabry I, Costantini E, Reyes E. Left sided heartport approach for combined mitral valve and coronary bypass surgery. Heart Surg Forum. 2000;3: Glower DD, Clements FM, Debruijn NP, Stafford-Smith M, Davis RD, Landolfo KP, et al. Comparison of direct aortic and femoral cannulation for port-access cardiac operations. Ann Thorac Surg. 1999;68: Lapietra A, Grossi EA, Pua BB, Esposito RA, Galloway AC, Derivaux CC, et al. Assisted venous drainage presents the risk of undetected air microembolism. J Thorac Cardiovasc Surg. 2000;120: Schroeyers P, Wellens F, De Geest R, Degrieck I, Van Praet F, Vermeulen Y, et al. Minimally invasive video-assisted mitral valve repair: short and mid-term results. J Heart Valve Dis. 2001;10: Mohr FW, Falk V, Diegeler A, Walther T, Gummert JF, Bucerius J, et al. Computer-enhanced robotic cardiac surgery: experience in 148 patients. J Thorac Cardiovasc Surg. 2001;121: Discussion Dr James Fann (Stanford, Calif). Dr Saunders, New York University has been one of the leaders in minimally invasive cardiac surgery and has indeed advanced our knowledge of mitral valve surgery by employing innovative techniques. I want to congratulate you and your colleagues on the presentation and the use of limited left thoracotomy approach for again bringing to our attention the use of this unique approach. Given the fact that only 4.3% of the nonsternotomy cases are performed in this fashion, one can consider this as probably a distant second when it comes to a nonsternotomy approach to the mitral valve. My questions mainly deal with the technical aspects of this procedure. The mitral valve is rotated from the conventional right-sided approach, as you mentioned, and I wonder if this angle of approach is more difficult: that is, is there any trick when it comes to exposing the mitral valve from the left side? Dr Saunders. Thank you very much for your comments. You are correct; this is definitely a distant second to the right anterior thoracotomy approach, but it has a very specific indication. While it is not our approach of choice, it is a valuable option in certain difficult patient situations. While we find the exposure to be very good, the valve is obviously upside down as compared to the right-sided approach. With respect to exposure, we find that silk retraction sutures and self-retaining retractors are all that we need to obtain good visualization. Dr Fann. In 50% of the cases the sixth intercostal space was used, and in 25% of the cases either the fourth or fifth intercostal space was used as the approach. Is there a good way of determining which intercostal space is the best approach for a left thoracotomy? Dr Saunders. There are no specific maneuvers we use to determine the intercostal space to use; mostly this depends on The Journal of Thoracic and Cardiovascular Surgery Volume 127, Number

7 individual surgeon preference and the patient s particular body habitus. Dr Fann. Two patients had direct aortic crossclamping. Why was this technique limited to 2 patients, as opposed to being utilized in more of the patients in this particular group? Dr Saunders. Those 2 were actually 2 of the first 3 that underwent this procedure. Exposure of the aorta is very difficult from this approach, especially in reoperative cases. Although some authors that have written about this approach routinely use direct aortic crossclamping, we feel that this is difficult as a standard technique. Dr Fann. There were no femoral arterial complications reported in this series, and this complication has been infrequent in previous series from New York University. Why has the preference been to use the descending aorta for cannulation? Dr Saunders. As our experience with right thoracotomy mitral valve surgery has evolved, we have moved away from routine use of endoballoon catheters toward direct ascending aortic cannulation and crossclamping. This serves to make the case simpler and more efficient and may decrease the bypass time and total case time. It also limits the number of complications associated with endoballoons, in terms of aortic dissection or balloon migration. Dr Fann. In this patient population, the frequency of atherosclerosis is typically not very high, but given your institutional experience with evaluating the ascending aorta prior to cannulation, do you examine the descending thoracic aorta with TEE for any intraluminal disease prior to cannulation? Dr Saunders. We do, using a combination of TEE prior to aortic cannulation and direct palpation of the aorta by the operating surgeon. Dr Fann. And in the fibrillatory arrest subset, do you think that the deairing is a problem, or is a transvalvular vent and flooding the field with CO 2 adequate? Dr Saunders. We find the deairing we can achieve from this approach to be adequate, but in addition to the transvalvular vent, we occasionally access the left ventricle directly, using a needle, for additional deairing. We also use the combination of typical maneuvers in changing the position of the table to augment deairing. Again, at the conclusion of the case, TEE is used to assess intracardiac air. Dr Fann. And finally, in the 2 patients with the perioperative strokes, were those cases performed with descending aortic cannulation and fibrillatory arrest, and what was the method of deairing in those 2 patients? Dr Saunders. Those 2 patients were actually early in our experience, and both had femoral arterial cannulation and endoaortic balloon clamping. There were no strokes in the later group, although we have to say that in our larger overall series of minimally invasive cases, we have never found a correlation between use of the endoballoon catheter and strokes The Journal of Thoracic and Cardiovascular Surgery April 2004