Asian Cardiovasc Thorac Ann 2006;14:252-253
© 2006 Asia Publishing EXchange Ltd
Mitral Valve Repair on the Beating Perfused Heart
Michael A Savitt, MD,
Taranpreet Singh, MCh1,
Guangqiang Gao, MD1,
Aftab Ahmed, MD1
Midwest Heart Surgery Institute, Milwaukee, USA
1 Providence St. Vincent Heart and Vascular Institute, Portland, USA
For reprint information contact: Michael A Savitt, MD Tel: 1 414 649 3787 Fax: 1 414 649 3794 Email: Savitt{at}midwestheartsurgery.com, St. Luke’s Health Science Building #1, 2901 W. KK River Parkway, Suite 511, Milwaukee, Wisconsin 53215, USA.
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ABSTRACT
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It is difficult to assess the success of mitral valve repair in the arrested heart. Various techniques have been described. Transesophageal echocardiogram (TEE) provides excellent two-dimensional evaluation of the repair, but three-dimensional anatomic characteristics are limited. We describe a simple technique for performing mitral valve repair on the beating heart. This allows accurate evaluation of valvular competence and three-dimensional anatomic characteristics prior to closure of the atriotomy.
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INTRODUCTION
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The key to success in mitral valve repair is the ability of the surgeon to assess the mitral valve prior to repair, in order to adequately define the problematic area, and after repair to ensure valvular competence. Various techniques have been described which essentially entail filling the left ventricle and inspecting the mitral valve in an arrested flaccid state. These maneuvers are not infallible and all evaluate the repair under non-physiological conditions. Currently, the best technique to assess post-repair mitral valvular comptence is with a transesophageal echocardiogram (TEE) on the beating heart after the discontinuation of cardiopulmonary bypass. Transesophageal echocardiogram provides excellent two-dimensional evaluation of the repair, but evaluation of three-dimensional anatomic characteristics is limited.
While TEE interpretation of residual mitral regurgitation and systolic anterior motion (SAM) is relatively standardized, there is often a level of uncertainty surrounding the true physiologic consequence of mild to moderate post-repair regurgitant jets. If the repair is deemed unsatisfactory, cardiopulmonary bypass must be re-established and the heart arrested, which can often be poorly tolerated in these patients. To overcome this limitation, mitral valve surgery performed on the beating heart with retrograde continuous oxygenated blood perfusion via the coronary sinus has been proposed.1 Retrograde cardioplegia may not adequately protect the right ventricle, which can be problematic in many patients with pulmonary hypertension.2 We describe a technique of performing mitral valve repair on the beating, continuously perfused (antegrade) heart. This facilitates accurate evaluation of valvular competence and three-dimensional anatomic characteristics prior to closure of the atriotomy, while assuring adequate myocardial protection.
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TECHNIQUE
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In all patients surgical access is achieved through a median sternotomy. Patients receive heparin (300 units·kg–1). Cardiopulmonary bypass is established via the standard technique using the ascending aorta and bicaval cannulation. Surgery is performed under moderate hypothermia (32°C). Flow during CPB is maintained at 2.5 L·min–1·m–2. The aortic root is cannulated using a DLP cardioplegia cannula and the ascending aorta is crossclamped. During the period of aortic crossclamp, the aortic root is perfused through the DLP cardioplegia cannula with oxygenated pump blood at a rate of 200 to 300 mL·min–1. A left ventricular (LV) vent is used. Atriotomy is performed in the inter-atrial grove beginning at the level of the right superior pulmonary vein and extending inferiorly. A standard left atrial retractor is used to expose the mitral valve which is assessed with the heart beating and full. Care must be taken to ensure adequate aortic root pressure as aortic regurgitation can occur with exposure of the mitral valve. The exact anatomical location of mitral regurgitation and its pathology are easily evaluated. The LV is filled with blood by turning the vent off or filling the LV via the vent tubing if necessary. Once the repair is completed, competency of the valve is re-assessed by filling the LV. Standard protocols of de-airing, weaning from CPB, and chest closure are followed. The electrocardiogram is continuously monitored and if any significant ST segment changes occur, the coronary perfusion flow is increased, taking care not to exceed a perfusion pressure of 120 mm Hg. The competence of the repair is confirmed with intraoperative TEE.
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DISCUSSION
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The traditional technique of mitral valve testing after repair is to fill the left ventricle with saline and assess the competency on an arrested flaccid heart. With this technique it is difficult to interpret leaks that need correction. Assessment of the mitral valve is more physiological when performed on the beating heart. Prior to repair, the exact site of regurgitation and coaptation of the leaflets can be seen, and after correction competency can be easily assessed. If regurgitation is present it can be repaired, or the valve replaced, prior to closure of the atriotomy.
There are a few reports which assess atrioventricular valvular competence on a fully loaded, beating heart.3 Gerak reported 23 cases of mitral valve repair or replacement performed on the beating heart using retrograde coronary sinus perfusion with warm oxygenated blood.1 There are also reports of combined aortic and mitral valve replacement on the beating heart with retrograde perfusion.4,5 It is well known that retrograde cardioplegia may not adequately protect the right ventricle, which can be particularly problematic in many patients with pulmonary hypertension.2 Continuous antegrade coronary perfusion on the other hand is more physiological, and imparts better protection to the right ventricle.
We are of the opinion that the perfused beating heart is very useful to assess mitral valvular three-dimensional anatomy both before and after repair. This approach reduces myocardial ischemia, which is especially beneficial in elderly patients who generally tolerate prolonged cardiopulmonary bypass poorly. To date we have performed 8 cases and all patients have had competent mitral valves confirmed by intraoperative TEE. One patient had a mild leak observed while testing transatrially, which was subsequently repaired prior to closing the atriotomy.
In conclusion we describe a technique of performing a mitral valve repair on the beating continuously perfused (antegrade) heart. This technical modification allows for accurate pre- and post-repair evaluation of three-dimensional mitral valvular anatomy while ensuring adequate myocardial protection.
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REFERENCES
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- Gersak B. Mitral Valve Repair or Replacement on the Beating Heart. Heart Surg Forum 2000;3:232–7.[Medline]
- Partington MT, Acar C, Buckberg GD, Julia P, Kofsky ER, Bugyi HI. Studies of retrograde cardioplegia. Capillary blood flow distribution to myocardium supplied by open and occluded arteries. J Thorac Cardiovasc Surg 1989;97:605–12.[Abstract]
- Miyamoto AT. Transatrial atrioventricular valve testing in the beating, fully loaded heart. Ann Thorac Surg 1996;61:1265–6.[Abstract/Free Full Text]
- Gersak B, Sutlic Z. Aortic and mitral valve surgery on the beating heart is lowering cardiopulmonary bypass and aortic cross clamp time. Heart Surg Forum 2002;5:182–6.[Medline]
- Lin H, He W, Liu T, Qin J, Luo Y, Liao S, et al. Aortic and mitral valve replacement with retrograde perfusion in the beating heart. Chin Med J 2001;114:1180–3.[Medline]
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ABSTRACT
INTRODUCTION
