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MMCTS
(March 28, 2008). doi:10.1510/mmcts.2007.002774 Copyright © 2008 European Association for Cardio-thoracic Surgery Procedure Tricuspid valve replacement with a bioprosthetic valveBluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University's Feinberg School of Medicine, 201 East Huron St, Suite 11-140, Chicago, IL 60611, USA * Corresponding author: Tel: +1-312-695-0454; fax: +1-312-695-1903 emcgee{at}nmh.org
Significant tricuspid regurgitation (TR) is present in many patients with heart failure. Valve replacement is necessary in patients in whom the valve is irreparable or in whom there is a high risk of late failure. The following manuscript and videos describe our approach to tricuspid valve replacement with a bioprosthetic valve.
Key Words: Heart failure • Tricuspid regurgitation • Valve replacement
The tricuspid valve is often considered in the workup of heart failure only after more prominent cardiac pathologies such as aortic, mitral, and coronary atherosclerotic disease have been discussed, and as such it has been referred to as the ‘forgotten valve.’ The sequelae of significant tricuspid regurgitation can be significant however and include ascites, hepatosplenomegaly, pleural effusions, and peripheral edema. Tricuspid regurgitation is usually secondary to left-sided valvular pathology (commonly the mitral valve) causing elevated pulmonary pressures with subsequent dilation of the tricuspid annulus. Rheumatic disease, Ebstein's anomaly, and endocarditis are other important causes of tricuspid incompetence. When significant tricuspid incompetence exists that we do not feel will resolve after left-sided reparative procedures, our preference is to repair the valve with a formal ring annuloplasty. If valve repair is not possible, then valve replacement is necessary.
A standard anesthetic for cardiac procedures is utilized. A pulmonary artery catheter placed via the right internal jugular vein is essential to assess pulmonary pressures pre- and post-repair. This catheter is temporarily withdrawn during valve replacement, and then replaced by the surgeon. Transesophageal echocardiography is used in all cases to evaluate the cardiac pathology, identify patent foramen ovale and assess the adequacy of repair.
Aortic and bi-caval cannulation is accomplished with direct cannulation of the superior vena cava (SVC) and inferior vena cava (IVC). We routinely utilize vacuum assistance up to –40 mmHg as it allows for smaller cannulae. Drainage is generally adequate using a 24fr wire wrapped right angle cannula in the SVC and a 26fr wire wrapped right angle cannula in the IVC. If there is no patent foramen ovale, we perform tricuspid procedures with the heart beating and perfused after all other aspects of the case requiring aortic crossclamping have been performed. Caval tapes are snared around the IVC and SVC to achieve right heart isolation. A caval clamp can be used alternatively in the setting of significant adhesions. An oblique right atriotomy is performed down to the IVC cannula, incorporating any exisiting retrograde catheter site. The foramen ovale is examined to ensure it is closed. A self retaining retractor is used. Occasionally pledgeted traction sutures are placed on the edges of the atriotomy to enhance exposure. A flexible weighted vent is placed in the coronary sinus (Video 1).
The tricuspid valve is inspected and an assessment of repair versus replacement is made. When repair is not feasible, our preference is to use a bioprosthetic bovine pericardial valve. The leaflets are left in place to preserve the sub-valvular apparatus. When prolapsing leaflets are large and bulky, they are fenestrated along a radial axis, which allows them to fold out of the way while preserving the tissue. Everting 2-0 pledgeted Ticron sutures are placed along the circumference of the annulus from the atrial to the ventricular side of the valve, starting at the anterior leaflet and working clockwise. Great care is taken when suturing near the AV node along the septal leaflet (Video 2, Schematic 1).
Standard valve sizers allow proper sizing of the chosen valve. The tricuspid annulus generally allows for large valve sizes and gradients across the valve are clinically insignificant with 27 mm or greater sizes. The valve must be oriented properly to avoid obstruction of the RVOT by the stent posts of the bioprosthetic valve. From the surgeons view, the posts should lie at the 12, 4 and 8 o'clock positions. A dental mirror is used to confirm that the RVOT is left unobstructed. The valve is seated and the sutures are secured starting at the septal leaflet (Video 3).
The pulmonary artery catheter is replaced through the valve and confirmed in position in the pulmonary artery by palpation. The atriotomy is closed with 4-0 polypropylene sutures in two layers after de-airing maneuvers. The caval tapes are released and the patient is weaned from cardiopulmonary bypass. It is our practice to place permanent epicardial pacing wires on all patients receiving a tricuspid valve replacement and leave them buried in a pocket on the left chest wall in case the need for subsequent permanent pacing arises. This avoids the issue of transvenous pacing leads injuring the prosthetic valve leaflets and causing recurrent tricuspid regurgitation. Temporary epicardial pacing wires are also placed in all patients given the higher incidence of transient conduction disturbances in the post-operative period following tricuspid procedures.
Tricuspid regurgitation secondary to endocarditis, rheumatic heart disease or congenital anomalies is best treated by valve replacement. In the setting of functional TR, it is our preference to repair the valve with a ring annuloplasty when possible. Risk factors for failure of tricuspid repair include a pre-operative tricuspid regurgitation score of 3+ or 4+, left ventricular ejection fraction of <35%, and the need for permanent pacing [1]. In these settings we will consider primary tricuspid valve replacement for functional TR. The technical aspects of tricuspid valve replacement are straightforward, and the procedure can be performed on the beating heart during the recovery periord after aortic cross-clamp removal. Injury to the conduction system is a surgical pitfall that can be avoided by cautious placement of sutures in the region of the A–V node. Some groups prefer a supra-annular implantation of prosthetic valves which leaves the coronary sinus and A–V node on the ventricular side of the valve so as to distance their sutures from the conduction system [2]. There is a potential risk of damage to the prosthetic valve leaflets by the pulmonary artery catheter if replaced through the valve, however, we have not found this to be a clinical problem when the catheter is left in place for <48 h as is our practice. The prophylactic placement of epicardial pacing leads in all patients may be seen as unnecessary treatment in patients who are in sinus rhythm after the procedure. However, we have had such patients ultimately develop a need for permanent pacing later in the post-operative course. Our strategy is therefore to place epicardial leads in all patients receiving a tricuspid valve. Doing so avoids pacing wires crossing the prosthetic valve which we believe leads to improved durability of the valve. Replacement of the tricuspid valve is a relatively infrequent procedure in most cardiac surgery practices. While not technically demanding, management of such patients has proved challenging as evidenced by high short- and long-term mortality rates. Contemporary and historical series have reported 30-day mortality rates in excess of 20%, and a 10-year survival of roughly 40–50% [3, 4, 5]. Risk factors that have been identified for operative mortality include emergent status, advanced age, and elevated pulmonary arterial pressures. Rheumatic or organic etiology of tricuspid valve disease is the main risk factor for late death as the disease process continues even after replacement [5]. Whether to replace the tricuspid valve with a mechanical or bioprosthetic valve remains a subject of debate. Bioprosthetic valve advocates point to the thrombosis rate of mechanical valves in the tricuspid position of 10–25%, and the bleeding complications of anticoagulation [6]. Neither valve type, however, has been shown to be a critical risk factor for short- or long-term death [3, 7, 8, 9]. It is our practice to implant bioprosthetic valves in the tricuspid position, even in young patients. We feel the durability is reasonable and the risk of thrombosis and bleeding outweigh the risk of redo heart surgery when needed in this population.
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