Thoracoscopically assisted mitral valve surgery (interventional procedures consultation)

NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE

Interventional Procedure Consultation Document

Thoracoscopically-assisted mitral valve surgery

Thoracoscopically-assisted mitral valve surgery involves the repair of a defective valve, using a camera to visualise the procedure, through small incisions between the ribs rather than one large incision through the breastbone (sternum). The patient is connected to a heart-lung machine, which temporarily takes over the function of the heart and lungs during the procedure.


The National Institute for Health and Clinical Excellence is examining thoracoscopically-assisted mitral valve surgery and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about thoracoscopically-assisted mitral valve surgery.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

  • comments on the preliminary recommendations
  • the identification of factual inaccuracies
  • additional relevant evidence.

Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that the Institute will follow after the consultation period ends is as follows.

  • The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
  • The Advisory Committee will then prepare draft guidance which will be the basis for the Institute's guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual.

Closing date for comments: 21 August 2007
Target date for publication of guidance: December 2007


Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.


1 Provisional recommendations
 
1.1 Evidence from large case series supports the safety and efficacy of thoracoscopically-assisted mitral valve surgery. Therefore, clinicians wishing to use this procedure should do so with normal arrangements for clinical governance and consent.
1.2 Thoracoscopically-assisted mitral valve surgery is technically demanding. Surgeons undertaking it should have special expertise and specific training in thoracoscopic cardiac surgery, and should perform their initial procedures with an experienced mentor.
1.3 Clinicians undertaking thoracoscopically-assisted mitral valve surgery should submit data on all patients to the Central Cardiac Audit Database (www.ccad.org.uk).
 
 
2 The procedure
 
2.1 Indications
 
2.1.1 Mitral valve surgery includes operations to repair or replace the mitral valve in patients with mitral stenosis, regurgitation or a combination of both.
2.1.2 Mitral valve disease can be treated medically to reduce the risk of congestive heart failure, and to control the often co-existing atrial fibrillation with its associated risk of thromboembolic stroke. However, many patients require surgery. Traditionally, mitral valve surgery is carried out through a median sternotomy. This allows excellent access to the heart and major vessels but recovery may be prolonged.
 
 
 
2.2 Outline of the procedure
 
2.2.1 This guidance relates to mitral valve surgery procedures which use thoracoscopic visualisation of the operative field for at least part of the operation.
2.2.2 Thoracoscopically-assisted mitral valve surgery is carried out under general anaesthesia. Cardiopulmonary bypass (CPB) is established using peripheral cannulation of arteries and veins in the thigh and neck. The aorta is occluded by inflation of an endoaortic balloon or placement of a transthoracic aortic cross-clamp. Cardioplegic solution is administered to achieve cardiac arrest and myocardial protection.
2.2.3 A number of small incisions are made in the chest wall between the ribs, without bone separation. In the totally thoracoscopic version of this procedure, mitral valve surgery is carried out entirely under thoracoscopic vision. However, hybrid approaches are used which combine direct and thoracoscopic visualisation of the operative field. The procedure may also be carried out with computer assistance.
 
 
 
2.3 Efficacy
 
2.3.1 A case series of 449 patients reported normal intraoperative valve function in 97% (318/327) of mitral valve repairs, and good functional results in all patients who underwent mitral valve replacement (n = 122).
 
2.3.2 A case series of 430 patients (62 undergoing valve repair), reported that mitral regurgitation (measured on a scale from 0 = no regurgitation to 4 = severe regurgitation) decreased from 3.1 preoperatively to 0.4 at a mean follow-up of 38 months after the procedure.
2.3.3 A case series of 306 patients (215 of whom underwent valve repair) with a median preoperative mitral regurgitation grade of 4 reported that 67% (145/215), 26% (56/215) and 7% (14/215) had a regurgitation grade of 0, 1, and 2 or 3 respectively at mean follow-up of 15 months.
2.3.4 A case series of 127 patients (114 of whom underwent mitral valve repair) reported that 95% (121) patients had a regurgitation grade of 4 pre-operatively. Of those who underwent mitral repair, 91% (104) had a regurgitation grade of 0 immediately after surgery and 89% (87/98) had a regurgitation grade of 0 at a mean follow-up of 8.4 months.
2.3.5 Approximately 76% (91/120) of patients in a third case series had a regurgitation grade of 0 at discharge.
2.3.6 In the case series of 430 and 127 patients, mean preoperative and postoperative heart failure New York Heart Association (NYHA) class improved from 2.8 to 1.4 (mean follow-up of 38 months) and 2.5 to 1.0 (mean follow-up of 14 months) respectively. The case series of 120 patients reported that 85% of patients (absolute numbers not given) were in NYHA class I at 3 months' follow-up.
2.3.7 The average length of stay in intensive care ranged from 22 to 41 hours in the eight case series. The average length of hospital stay ranged from 4.5 to 11 days. For more details, refer to the sources of evidence (see appendix).
2.3.8 The Specialist Advisers listed key efficacy outcomes as survival, success of the operation in repairing or replacing the valve, long term durability of repair or replacement, postoperative pain, operating time, CPB time, duration of intensive care, length of hospital stay, return to full activity, requirement for blood transfusion, cosmetic results and unplanned repeat operation.
 
 
2.4 Safety
 
2.4.1 Four of the eight case series reported hospital mortality of 0% (0/120) patients, 0.8% (1/127), 4% (39/1059) and 4% (18/449) in patients who underwent thoracoscopically-assisted mitral valve surgery. Thirty-day mortality was reported as 2% (9/441), 0.2% (1/430), and 1% (3/306) of patients in a further three case series.
2.4.2 Five studies reported that bleeding requiring repeat surgery occurred in 0.9% (4/430), 3% (3/121), 4% (17/441), 5% (48/1059), and 8% (26/306) of patients.
2.4.3 New-onset atrial fibrillation was the most common perioperative complication in the eight case series, occurring in approximately 10% of 1059 patients who underwent mitral valve in an international registry and reported in 3% (12/430), 17% (absolute numbers not reported) 17% (20/120) and 18% (22/121) of patients in four further studies.
2.4.4 Conversion to sternotomy was reported in 0% (0/120), 0.8% (1/127), 1% (4/449), 2% (6/306), 3.8% (50/1059) and 4% (5/127) of patients. The reasons for conversion included aortic dissection, left ventricular wall injury, inadequate CPB flow, 'vascular injury', 'patient anatomy', 'poor visualisation', insufficient venous return, ruptured breast implant, failure of the thoracoscope system, insufficient working space, femoral arterial disease and marked aortic tortuosity. For more details, refer to the sources of evidence (see appendix).
2.4.5 The Specialist Advisers stated that potential adverse events include death, aortic dissection, myocardial infarction, prolonged cross clamp and CPB times leading to poor myocardial preservation, maintenance of satisfactory cardioplegia, compromised quality of mitral valve repair (possibly requiring repeat surgery), damage to peripheral vessels due to cannulation, peripheral vascular disease, paravalvular leakage, stroke, perioperative bleeding, lung injury, heart failure and renal failure.
 
   

Bruce Campbell
Chairman, Interventional Procedures Advisory Committee
July 2007

Appendix: Sources of evidence
 

The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making its provisional recommendations.

  • 'Interventional procedure overview of thoracoscopically-assisted mitral valve surgery, April 2007'

Available from: www.nice.org.uk/ip402overview.

This page was last updated: 30 March 2010