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Minimally Invasive Mitral Valve Surgery

José Luis Navia, MD

From the Department of Thoracic and Cardiovascular Surgery,
The Cleveland Clinic Foundation, Cleveland, Ohio, USA

INTRODUCTION
   Full median sternotomy has been a standard surgical approach for heart surgery for more than 30 years. Full sternotomy provides excellent exposure to the heart and the vessels, also allows central cannulation for cardiac pulmonary bypass for any kind of cardiac surgery procedures (1,2, 3,9, 10,11). However, recently there has been several reports of less invasive technique for cardiac valve surgery, and surgeon around the world now are repairing or replacing cardiac valves through smaller incisions, with safety, more confidence and good results (4, 5,8). With the recent advance of minimally invasive technique in our surgical field, cardiac surgery has embarked in the development in new less invasive process to reach the heart. During the last 5 years there has been a considerable amount of progress in the development of less invasive technique for heart valve surgery. This involves small chest wall incision to gain access to the heart, advances in cardiopulmonary perfusion, instrumentation, intracardiac visualization, as well as voice activated camera and computer robotic assistant to facilitate the new surgical procedure (6, 7,9). After the evolution of the minimally invasive valve procedure in our department, that includes the right parasternal incision and the transecting sternotomy, we have concluded that the partial upper sternotomy is an incision of choice for minimally invasive heart valve surgery, and we use a vertical transeptal atrial incision to exposure the mitral valve.

   This incision afforded good exposure for both mitral valve repair and replacement (22). The conversions rate to full sternotomy was less than 3%. Also the latest of the surgical ICU stay and hospital stay were low. Partial upper sternotomy and mini sternotomy provides the surgeon with a familiar surgical field, and the standard transeptal incision provides excellent exposure of the mitral valve, mostly in patients with small left atrium cavity. Nearly all patients with isolate mitral valve pathology are candidates for this approach. This approach satisfies the criteria that defines successful minimally invasive valve surgery. The purpose of this review is to describe the experience in our institution in minimally invasive mitral valve surgery by partial upper sternotomy and transeptal approach.

SURGICAL TECHNIQUE
   The patient is positioned in supine position on the operating table, standard hemodynamic monitor lines are placed, and the patient is intubated with a single lumen endotracheal tube. Transesophageal echocardiogram probe is place, and is used to evaluate the mechanism of valve pathology, detection of any changes in regional or global left ventricular function and to de-air the heart after the operation. The defibrillator pads are placed on the patient's back and anterior left chest. An 8-cm skin incision is made from the sternal angle to the forth-intercostal space. The soft tissue is dissected with an electrocautery and the flap is raised to allow good access to the sternal notch. The sternum is open from the sternal notch to the four intercostal space with the incision "J" off to the left. (Fig. 1)

Fig 1: Partial upper sternotomy extends from the sternal notch to the left forth-intercostal space.

   The left internal thoracic artery is preserved. A small two-blade retractor is placed and the upper sternum is opened. The anterior pericardium is opened slightly to the patient right and tacked to the drapes under tension with a heavy stay suture. To help reduce the potential for air emboli, a cannula is sewn to the upper edge of the wound and the operative field is filled with CO2 at 6 liters per minute. This displaced oxygen and nitrogen, bubbles of CO2 that enter circulation are absorbed. (12,13) After heparinization, the aorta is cannulated with a 20-F size soft cannula (3M Healthcare, Ann Arbor, MI). The pericardial reflection overlaying the superior vena cava (SVC), is transected anteriorly and the dissection of the vessel is carried on around its entire circumference. An umbilical tape is placed around the SVC. A 22-F right angle cannula is placed in the superior vena cava and a second 22 -F straight cannulas is placed through the posterior region of the right atrial appendage into the inferior vena cava. The antegrade cardioplegia cannula is inserted in the ascending aorta. Cardiopulmonary bypass is established with active negative pressure on the venous line (-50 cm H2O), and the heart is decompressed. The patient is kept normothermic, the aorta is cross-clamped, and antegrade cardioplegia solution is administrated. Snares previously placed around inferior and superior vena cava are tightened. The planned incision in the right atrium is indicated in Fig. 2.

Fig. 2: The ascending aorta, right atrium and pulmonary artery are visualized. Cannulae are placed in the ascending aorta, superior and inferior vena cava. The right atrium incision is indicated.

   Mitral valve is approached by transseptal incision that is extended into the dome of the left atrium. The right atrial incision is started in the right atrial appendage and extended cephalad towards the dome of the left atrium and caudal towards the inferior vena cava. A cannula is placed in the coronary sinus for delivery of retrograde cardioplegia. The atrial septum is opened in the posterior portion of the fossa ovalis, and the incision is cephalad extended with a gentle curve onto the dome of the left atrium (Fig 3).

Fig. 3: The right atrium free wall and appendage are opened. The incision in the interatrial septum is indicated. Retrograde cardioplegia cannula is placed into the coronary sinus.

   Sutures are placed through the super portion of the septum and retract towards the patients left. (Fig 4)

Fig. 4: The atrial septum is opened and the incision is extended into the dome of the left atrium. Stay pledgetted sutures are placed in the septum to expose the mitral valve.

   Two handle retractors are placed in the superior portion of the left atrium. This maneuver shows excellent exposure of the mitral valve (Fig 5).

Fig.5: Self-retractors provide better exposure of the mitral valve.

   Figure 6, 7 and 8 show the complete mitral valve repair and annuloplasty.

Fig. 6: Annuloplasty stitches are placed on the mitral annulus, and then passed through the annuloplasty Cosgrove ring.

Fig. 7: The annuloplsty ring is seated in place.

Fig. 8: The mital valve repair is completed.

   The incision in the left atrium is closed with a continuous 4-0 polypropylene suture. Before closing of the incision in the interatrial septum, air is evacuated from the left atrium by inflating the lung and with retrograde cardioplegia delivery (Fig 9).

Fig. 9: The interatrial septum is closed and the left cavity is de-airing.

   The retrograde cardioplegia cannula is removed before closing the right atrium. De-airing of the left ventricle is facilitated by gently suction on the cardioplegia cannula in the aorta before and after removal of aorta cross clamp. De-airing is guided with a transesophageal echocardiogram. The incision in the right atrium is closed with a 4-0 prolene and the pacemaker wires are placed before removal of the aortic cross clamp (Fig 10).

Fig. 10: Finally the right atrium is closed. Atrial and ventricular pacing wires are placed.

After normal cardiac function has returned the patient is weaned from cardiopulmonary bypass and the cannulas are removed in the usual fashion. One or two 28-F chest tube is placed, depending on whether the right pleural space has been disturbed. The sternum is closed with four sternal wires; soft tissue and skin are closed in layers (Fig 11).


Fig. 11: The final skin incision and chest tube drainage.

RESULTS
   From July 1996 to December 2000 the minimally invasive valve surgery with the extended transeptal approach, 1,21,was used to perform mitral valve surgery in 1164 patients, mean age of the patient was 57 ±11 years (range, 20 to 85 years), 63% of patients were male. Left ventricular function was normal in 81% of patients, mildly impaired in 14%, moderately in 3%, and severe left ventricular dysfunction was present in 2% of the patients. The indications for mitral valve surgery was valve insufficiency in 90% of patients, mitral stenosis in 4%, and mixed pathology in 6% of patients. In terms of etiology, degenerative mitral valve was present in 82% of the patients, rheumatic 9%, and endocarditis 2%, congenital 1%, ischemic 1% and others 5%. Mitral valve surgery repair was accomplished in 89% of the patient, replacement in 11%, consisting 73 patients underwent mechanical mitral St Jude valve and 53 patients were performed with a Carpentier Edwards tissue valve. In the year 2000 isolate mitral valve procedure were performed in 445 patients, minimally invasive approached was used in 84% of the patients and just only 16% of the patients underwent conventional approach with full sternotomy. From the entire population, 1164 patients, mitral valve repair with annuloplasty ring was used in more than 95% of the patients, leaflet resection closed to 90% of the patient, chordal transfer in 5% of the patient, commisurotomy 2%, cleft repair 3%, and papillary muscle shortening 1% of patients. The most common cause for conversion to sternotomy was inadequate exposure in 9 patients, the others causes of conversion to full sternotomy were bleeding in 3 patients, arterial cannulation in 3 patients, revascularization in 2 patients, SAM in 1 patient, and other in 3 patients, with a total of conversion to sternotomy was 1.8%. All patients remained intubated after surgery and were taken to intensive care unit for recovery. The mean intubation time was 5.3 hours, 59% of patients were intubated less than 6 hours, and 50% of patients were in ICU less than 24 hours, with the mean of ICU stay of 28 hours. Sixty-five percent of patients were discharged within 6 days of surgery. 92% of the patients received no blood product during their hospitalization; the mean transfusion unit was 1.6 unit. Because of minimally invasive approach, chest tubes drainage less than 100cc per hour for 2 consecutive hours are considered normal postoperative bleeding. Using this criteria 40 of the patients return to the operating room for possible bleeding (3.4 %).

   Postoperative complications included respiratory insufficiency 8%, stroke 1.8%, and wound infections 0.7%, myocardium infarctions 0.2%. Transient pericarditis was common, however this was usually resolved by the time the hospital discharge. Four percent of patients required permanent pacemaker implantation for the postoperative heart block or bradycardia. The predictors of the possible pacemaker implant, were advance in age, renal disease, reoperation and valve replacement. There were three hospital deaths resulting in a hospital mortality of 0.2%.

CONCLUSION
   In the last five years less invasive technique has emerged as a revolutionary concept for performing cardiac surgery, with a potentially main gold of reducing surgical trauma and speed patient recovery (14, 15,17). Despite widespread adoption of these new procedures has been slow; many surgeons around the world have learned minimally mitral valve surgery with excellent levels of safety, expertise and overall good results. Mitral valve surgery requires cardiopulmonary bypass therefore new approaches to the mitral valve entail changing the chest wall incision, the incision of the heart and the cannulation strategy for cardiopulmonary bypass. The primary focus of the new minimally invasive technique for mitral valve surgery is to provide some benefit to the patient in terms of minimized both musculoskeletal and cardiac trauma by performing a small chest wall incision. Another potential advantage of the less invasive approach includes reduce pain, reduce bleeding, lower incidence of groin infection, less blood less, early hospital discharge and return to full activity and improve cosmetic results. For surgical trauma results in early extubation, shorter ICU stay and shorter hospital stay. This factor in time decreases hospital charges by 10-20%. The development of partial upper sternotomy at the Cleveland Clinic has been an evolving process that began with a right parasternal incision and end with an upper small sternotomy. Several advantages of the partial upper sternotomy make this logical choice for mitral valve surgery. The mitral valve and aorta are midline structures and are approached easily by midline incision (7). This incision, allows central cannulation for cardiopulmonary perfusion in all cases and avoid potential complications for peripheral retrograde systemic perfusion and cannulation, and also reduce the risk for reoperation. The surgical field is familiar for the surgeon so this result in shortened learning curve for the cardiac surgeon. Finally, the cosmetic result and patient satisfaction has been excellent. This advantage of the minimally invasive heart valve surgery may be realized after a relative short learning curve by the surgeon. With the evolution of the new technology in cardiopulmonary bypass, and the increasing surgeon experience, all primary heart valve operations can be performed safely through the small incision. In the future advance robotic and three-dimensional intracardiac cameras are likely to facilitate through micro invasive technique to accomplished different mitral valve operations (6,7,17,18,19,22,23). However, using the current technology our incision for primary valve surgery is the partial upper sternotomy with a extended vertical transeptal incision to approach the mitral valve, providing excellent intracardiac exposure (24, 25,26). To date more than seventeen hundred patients have had aortic and mitral valve surgery through this approach at our institution and the result has been excellent, showing that this new surgical technique can be accomplished successfully. Finally, in our experience, the advantages of the minimally invasive technique remain substantial, with decrease in recovery time, blood loss, transfusion requirements, shorter ICU and hospital stay, reducing hospital cost, without compromising surgical efficacy. This creates a positive impact in the patient social life, returning early to full activity, and is more cosmetics attractive to the patient. These benefits suggest that minimally invasive mitral valve surgery is safe, effective, and applicable for most patients with mitral valve disease.

ABSTRACT
During the last four years, we have been performed different less invasive approaches for cardiac valve surgery, and we have concluded that the partial upper sternotomy and an extended transseptal incision provide excellent exposure for mitral valve surgery, avoiding the median sternotomy. From July 1996 to December 2000, 1,164 patients have mitral valve surgery using the minimally invasive approach. Eighty-nine percent of patients have mitral valve repair and 11% have mitral replacement. Consisting in 73 patients underwent St Jude mechanical valve and 53 patients pericardial tissue valve. Twenty-one patients (1.8%) required emergent sternotomy, and all other patients had the procedure completed using the initial approach. Fifty-nine percent of the patients were intubated less than six hours and the mean intubation time was 5.3 hours. Forty-eight percent of the patients spent less than 24 hours in the intensive care unit. Length hospital stay was 6.5 days. 8% of the patients received transfusion; the mean transfusion was 1.6 units. Hospital mortality was 0.2% (3 pt.) Morbidity includes reoperation from bleeding 3.4%, respiratory insufficiency 0.8%, stroke 1.8%, and wound infections 0.7%. We can conclude that the mitral valve procedure including complicated repairs can be performed by a partial upper sternotomy with an extended transseptal incision. This approach provides excellent exposure for mitral valve and can be accomplished safely without jeopardizing clinical results.

REFERENCES

1. Navia JL, Cosgrove DM III: Minimally invasive mitral valve operations. Ann Thorac Surg 62:1542-1544, 1996

2. Cosgrove DM, Gillinov AM: Partial sternotomy for mitral valve operations. Operative Techniques in Cardiac & Thoracic Surgery 3:62-72, 1998

3. Loulmet DF, Carpentier A, Cho PW, et al: Less invasive techniques for mitral valve surgery. J Thorac Cardiovasc Surg 115:772-779, 1998

4. Gundry SR, Shatttuck OH, Razzouk AJ, et al: Facile minimally invasive cardiac surgery via ministernotomy. Ann Thorac Surg 65:1100-1104,1998

5. Svensson LG: Minimal-access "J" or "j" sternotomy for valvular, aortic, and coronary operations or reoperations. Ann Thorac Surg 64: 1501-1503, 1997

6. Chitwood WR Jr, Elbeery JR, Moran JF, et al: Minimally invasive mitral valve repair using transthoracic aortic occlusion. Ann Thorac Surg 63:1477-1479,1997

7. Mohr FW, Falk V, Diegeler A, et al: Minimally invasive port-access mitral valve surgery. J Thorac Cardiovasc Surg 115:567-576, 1998

8. Fann JI, Pompili MF, Burdon TA, et al: Minimally invasive mitral valve surgery. Semin Thorac Cardiovasc Surg 9:320-330, 1997

9. Schwartz DS, Ribakove GH, Grossi EA, ea al: Minimally invasive mitral valve replacement: Port-access technique, feasibility, and myocardial functional preservation. J Thorac Cardiovasc Surg 113:1022-1031, 1997

10. Cosgrove DM III, Sabik JF, and NAVIA JL: Minimally invasive valve operations. Ann Thorac Surg 65:1535-1539, 1998

11. Cohn LH, Adams DH, Couper GS et al: Minimally invasive cardiac valve surgery improves patient satisfaction while reducing costs of cardiac valve replacement and repair. Ann Surg 226:421-428, 1997

12. Peters WS, Smith Ja, Preovolos A, et al: Mitral valve replacement via a right mini thoracotomy in the dog: Use of carbon dioxide to reduce intraardiac air. Eur J Cardiothorac Surg 11:1067-1073, 1997

13. Eguchi S, Sakurai Y, Yamaguchi A: The Use if carbon dioxide gas to prevent air embolism during open heart surgery. Acta Med Biol 11:1-13 1963

14. Kasegawa H, Shimokawa T, Matsushita Y, et al: Right- sided partial sternotomy for minimally invasive valve operation: "Open door method." Ann Thorac Surg 65:569-570, 1998

15. Nair RU, Sharpe DAC: Limited lower sternotomy for minimally invasive mitral valve replacement. Ann Thorac Surg 65:273-274, 1998

16. Arom KV, Emery RW: Minimally invasive mitral valve operations (Letter to the editor). Ann Thorac Surg 65:569-570, 1998

17. Carpentier A, Loulmet D, Carpentier A, et al: First open heart operation (mitral valvuloplasty) under videosurgery through a minithoracotomy. C R Acad Sci Paris 319:219-223, 1996

18. Chitwood WR Jr, Elbeery JR, Chapman WHH, et al: Video-assisted minimally invasive mitral valve surgery: The "micro-mitral" operation. J Thorac Cardiovasc Surg 113:413-414, 1997

19. Falk V, Walther T, Autschbach R, et al: Robot-assisted minimally invasive solo mitral valve operation. J Thorac Cardiovasc Surg 115:470-471, 1998

20. Guiraudon GM, Ofiesh JG, Kaushik R: Extended vertical transatrial septal approach to the mitral valve. Ann Thorac Surg 52:1058-1062, 1991

21. Aklog L, Adams DH, Couper GS, et al: Techniques and results of direct-access minimally invasive valve surgery: a paradigm for the future. J Thorac Cardiovasc Surg 116:705-715, 1998

22. Carpentier A, Loulemet D, Carpentier A, et al: Chirurgie a coeur par video-chirurgie et mini-thoracotomie: Premier cas (valvuloplastie mitrale) opree succes. Comptes Rendes De L'Academie des Sciences: Sciences de la Vie 319:219-223, 1996

23. Lin P, Chang C, Chu J, et al: Video-assisted mitral valve operations. Ann Thorac Surg 61:1781-1787, 1996

24. Gundry SR, Shattuck OH, Razzouk AJ, et al: Facile minimally invasive cardiac surgery via ministernotomy. Ann Thorac Surg 65:1100-1104,1998

25. Konertz W, Waldenberger F, Schmutzler M, et al: Minimally access valve surgery through superior partial sternotomy: A preliminary study. J Heart Valve Dis 5:638-640, 1996

26. Tam RK, Ho C, Almeida AA: Minimally invasive mitral valve surgery. J Thorac Cardiovasc Surg 115:246-247, 1998

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2nd Virtual Congress of Cardiology

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