Bentall Procedure

pediagenosis    June 25, 2020    Cardiovascular , Organ   

Bentall Procedure

Keywords: Bentall Procedure, Operations for Valvular Heart Disease, bentall, aortic replacement, valve replacement, composite aortic valve, aortic replacement.

Abstract

The Bentall procedure technique has evolved to become a standardized, reliable procedure that can be performed for a variety of aortic vavle and aortic root pathology. The technique described in this chapter describes the details of the author’s technique and variations for specific pathology. Myocardial protection and cerebral protection is discussed.

·   In 1968, Bentall and De Bono1 described a technique for composite aortic valve and root replacement with reimplantation of the coronary arteries. The coronary arteries were sewn to the graft as a side-to-side anastomosis, and the aneurysm wall was wrapped around the graft.

·    During the ensuing years, this technique underwent various modifications, primarily because of pseudoaneurysm formation at the side-to-side anastomosis of the coronary button to the graft.

·    The Bentall operation currently uses a technique for treating combined disease of the aortic valve and aortic root with an end-to-side coronary button technique, a modification of the original technique described by Kouchoukos et al. in 1991.²

·  All procedures are performed by creating an open distal anastomosis when there is an inadequate cuff of normal aorta below the cross-clamp or by replacing the entire arch or hemiarch during a period of moderate or deep hypothermic circulatory arrest with antegrade cerebral perfusion or total circulatory arrest with or without retrograde venous perfusion.

·   The modified Bentall procedure is the procedure of choice when treating the aortic valve, aortic sinuses, and ascending aorta.

Step 1. Surgical Anatomy

·     The pertinent anatomy consists of the aortic valve and related pathology, sinuses of Valsalva, coronary ostia, ascending aorta, and aortic arch. Specific pathologic processes present different challenges in a Bentall procedure. The more common situations are bicuspid aortic valve stenosis (AS) or aortic regurgitation (AR) with a dilated ascending aorta, AR and ascending aortic aneurysm (e.g., Marfan syndrome), and acute or chronic aortic dissection.

Step 2. Preoperative Considerations

· The planning of the procedure requires preoperative echocardiography and cardiac catheterization with coronary angiography and optional aortic root angiography with panning into the aortic arch. A carotid artery Doppler examination may be useful. The use of a contrast magnetic resonance imaging (MRI) or computed tomography (CT) scan with three-dimensional reconstruction is standard to help measure the extent and size of the aneurysm.

·  The choice of valve should be determined in consultation with the patient. If there is no associated coronary disease, the procedure can be performed through a ministernotomy. In this case, peripheral venous cannulation is often necessary because of limited access to the right atrial appendage.

·    The need for circulatory arrest and possible electroencephalographic monitoring should be determined if the arch is involved or if the aneurysm extends distally to the level of the innominate artery, requiring circulatory arrest to perform an open anastomosis. When circulatory arrest is required, decisions about cerebral protection need to be made with regard to technique, cardiopulmonary bypass (CPB) setup, temperature, and antegrade perfusion.

·    A plan for cardioplegia administration is essential, especially if a ministernotomy is to be used. I prefer antegrade and retrograde del Nido blood cardioplegia readministered every 60 to 90 minutes.

·  Special consideration is given to the treatment of postprocedure coagulopathy. Administration platelets, coagulation factors, and possible factor VII may be necessary. I use heparin-coated CPB circuits. In addition, a Rotem device (Tem International, Basel, Switzerland) is used to guide component therapy for postoperative coagulation.

Step 3. Operative Steps

·    The Bentall procedure can be performed through a median sternotomy or ministernotomy, with a 4-cm vertical skin incision over the upper sternum and the midsternal split extending from the sternal notch to the right fourth interspace (J-shaped sternotomy).

·  Cannulation sites can be into the ascending aorta, transverse arch, femoral artery or, preferably, into a 6- or 8-mm Dacron graft anastomosed end to side to the right axillary artery. Axillary perfusion provides antegrade flow, facilitates antegrade cerebral perfusion if the innominate artery is clamped, and is especially useful in cases of aortic dissection.

·    The site chosen for cannulation depends on the anatomy, extent of pathology, and indications for the operation. For example, the axillary artery is preferred for all cases in which circulatory arrest is to be used. The upper ascending aorta or arch is a safe and convenient site in aneurysmal disease. If the replacement extends into the aortic arch, the arterial perfusion cannula will be removed during the circulatory arrest period, with subsequent direct cannulation of the graft or through a side limb.

·    Venous cannulation is through the right atrial appendage, with a triple-stage cannula or long femoral venous cannula, inserted by cutdown through a purse-string suture or percutaneously with a Seldinger technique. The position of the cannula in the right atrium is confirmed with transesophageal echocardiography (TEE).

· To protect the heart, a cold blood cardioplegia solution or del Nido solution is infused antegrade directly into the aorta (if there is no aortic insufficiency [AI]), via the coronary ostia, and retrograde through the coronary sinus. A topical cold saline solution augments myocardial cooling. A del Nido solution provides excellent myocardial protection and should be readministered every 60 to 90 minutes. It also does not require a reperfusion strategy.

·   Systemic cooling to a temperature of 34°C (93.2°F) is sufficient for routine replacement of the aortic root, but a temperature of 12°–18°C (53.6°–64.4°F) is necessary if a total circulatory arrest technique is used. An isoelectric tracing on the electroencephalographic monitor can be a biologic guide to circulatory arrest. An antegrade cerebral perfusion (18°C; 64.4°F) technique can be used with moderate systemic hypothermia at 25°C (77°F).

·  An optional left ventricular (LV) vent inserted into the right superior pulmonary vein or pulmonary artery vent facilitates decompression of the LV. With severe AI, the heart will distend in spite of venting the left ventricle, especially during fibrillation induced during the cooling period.

·    Cardiac distention during cooling will require cross-clamping the aorta and the initiation of cardioplegic arrest. As cooling continues, the proximal portion of the procedure can be performed valve replacement and coronary button reimplantation. As soon as the goal systemic temperature is achieved in circulatory arrest cases, the proximal portion of the procedure is stopped and the arch replacement performed. Antegrade cerebral perfusion can extend the safe circulatory arrest time. Retrograde superior vena cava (SVC) perfusion is most effective in preventing the embolization of debris and air in very atherosclerotic aneurysms. In addition, monitoring bilateral near-infrared oxygen saturation over the forehead helps guide the possible need (e.g., a reduction in left-sided oxygen saturation) for direct perfusion of the left carotid in addition to the right carotid perfusion by clamping the innominate artery.

·    After the arch replacement is completed, the graft can be cannulated. If the axillary artery has been used, antegrade perfusion and de-airing of the arch are initiated. The graft is clamped, and rewarming is begun. The proximal portion of the procedure is completed. Finally, the graft to graft anastomosis is completed.

1. Proximal Portion of the Procedure

·  The aorta is transected below the cross-clamp, leaving a cuff of aorta for the distal anastomosis. The proximal aorta is opened with a longitudinal incision. The incision is extended toward the noncoronary sinus to avoid the right coronary artery ostia, which may have migrated high due to the aneurysm. Sinus aneurysm tissue is excised, leaving a 2–3 mm rim. Buttons of aortic tissue around the ostia of the coronary arteries are created and mobilized (Fig. 14.1).

·  The right coronary artery must be adequately mobilized to prevent torsion after reanastomosis to the graft (Fig. 14.2).

·    The aortic valve is excised and the annulus is débrided of all calcium. After sizing of the aortic annulus, a series of pledgeted mattress sutures is placed (Fig. 14.3).

·      If a bioprosthetic valve is to be used, the suture needle is passed from the ventricular to the aortic aspect of the annulus for fixation of the valve in a supraannular position.

·      For a mechanical prosthetic valve, the sutures are placed from the aortic to the ventricular aspect of the annulus to effect intraannular fixation of the valve (Fig. 14.4). If the annulus is smaller than 23 mm, a supraannular suture technique is an option.

·    Fig. 14.4 shows details of the intraannular everting technique for valve implantation. The everting technique is preferred for mechanical valve conduits. Visualization of this anastomosis for hemostasis will not be possible until the heart is ejecting, and inspection of the annular areas beneath the coronary buttons will be almost impossible. These sutures must be placed close together and tied tightly to create a hemostatic seal. In addition, a running 3-0 prolene from the remaining aortic wall to the sewing cuff of the valve conduit enhances hemostasis.

·    If the annulus is small and a larger valve is desired, a mechanical valve can be placed in a supraannular position using the infraannular suture technique needed for the bioprosthetic valve.

·    A composite graft consisting of a St. Jude valve and a Hemashield or Gelweave graft is used in patients for whom a mechanical valve is indicated (Fig. 14.5).

·    In patients for whom a biologic valve is chosen, a homemade composite, consisting of a stented pericardial valve and Gelweave graft, is used. The size of the graft should equal the outer diameter of the valve sewing cuff. Running 4-0 polypropylene sutures are used to attach the graft to the sewing cuff of the valve.

·    A homograft or autograft (Ross procedure) is an alternative composite biologic conduit.

·    After the valve sutures are secured, 3-0 Prolene sutures are run from the aortic wall to the valve sewing cuff to aid in hemostasis. Then buttons of the coronary ostia are anastomosed. Minimal mobilization of the left coronary artery is necessary. The first centimeter of the right coronary artery is mobilized. The buttons are implanted in an end-to-side fashion with running 5-0 or 6-0 Prolene sutures, incorporating a Teflon felt strip to reinforce the suture line (Fig. 14.6).

·    After attachment of the left coronary artery is completed, the length of the graft is determined by clamping the distal end of the graft and stretching the graft by distending it with antegrade cardioplegia. The left main suture line is tested for leaks during this maneuver. Excess graft material is removed with the ophthalmic cautery to prevent fraying of the Dacron material. The distal graft to the aorta or graft to graft anastomosis (if an arch replacement was performed) is completed with 4-0 polypropylene sutures and a Teflon strip to reinforce the suture line.

·    Cardioplegia is readministered antegrade into the graft. With the graft distended, the correct position to anastomose the right coronary button can be accurately determined to avoid tension and torsion (Fig. 14.7). The right coronary artery is sewn (5-0 or 6-0 polypropylene sutures) to the graft. Warm cardioplegia is administered antegrade into the graft, allowing a final check of the suture lines for bleeding, before completing the air maneuvers and removal of the cross-clamp.

·    Rarely, the coronary arteries cannot be mobilized to reach the prosthetic aortic graft. Dacron graft extensions are a possible option (Fig. 14.8).

·   The Cabrol technique, using a simple Dacron graft (8 mm), is illustrated in Fig. 14.9. The ends of the tubular graft are sewn end to end to the coronary arteries. The length and orientation of the graft should be carefully planned. The body of the graft is sewn side to side to the aortic graft, providing inflow and distribution to the coronary arteries.

2. Bentall With Arch Replacement

·     To allow an open distal anastomosis or total aortic arch reconstruction, the patient’s head is placed downward, CPB is discontinued, and antegrade cerebral perfusion with 18°C (64.4°F) blood is begun. The aorta is excised appropriately. The anastomosis between the trimmed Dacron graft and aorta is performed with 4-0 polypropylene running sutures, reinforced by an outer Teflon felt strip. Before CPB is resumed, the head vessels are carefully inspected for air and particulate debris. Selective cerebral perfusion is discontinued and, in cases with an especially high risk of embolization, a brief period of retrograde perfusion through the SVC at a pressure of 20 mm Hg, can be useful to flush out air and debris further.

·   After reestablishing CPB, the arch graft is clamped and warming begun. If the Bentall portion of the procedure needs to be complete, this is done at this time. Finally, the graft (arch) to graft (ascending aorta) anastomosis is completed.

·     Air from the graft and cardiac chambers is removed after releasing the cross-clamp. The aortic root vent is maintained on suction.

·   The heart is reperfused and allowed to resume sinus rhythm. Defibrillation is used if necessary. Atrial and ventricular bipolar pacing wires are placed. Adequacy of air removal from the cardiac chambers is monitored with TEE.

·    CPB is discontinued when a bladder temperature of 37°C (98.6°F) is reached. Hemostasis often requires transfusion of clotting factors and platelets. Appropriate drainage tubes are placed in the mediastinum.

·     A variety of biologic glues is available. It is often helpful to seal the suture lines with glue when they are dry. When used, the glue should be applied sparingly. Overapplication of glue may prevent observation of important surgical leaks that require suture repair. In most cases, I do not use glue. Only when the aorta is very friable, thin, or dissected do I apply biologic glue.

Step 4. Postoperative Care

·    The basic principles of hemodynamic monitoring of the cardiac surgical patient after aortic valve replacement apply. Specific considerations relate to the extent of root and arch replacement. Neurologic assessment is important. Close monitoring for excessive bleeding or tamponade is essential and may prompt an urgent return to the operating room for exploration and evacuation of hematoma. Monitoring for myocardial ischemia or right ventricular dysfunction can indicate a problem with the coronary buttons, most commonly the right button.

·   If a mechanical composite conduit was implanted, anticoagulation with warfarin can be started on the first postoperative day. I do not use heparin unless the international normalized ratio (INR) has not responded by the third postoperative day. The target INR is 2.5. If a bioprosthetic composite valve has been used, I do not prescribe warfarin, only aspirin.

·  The recent introduction of home testing of coagulation status offers an opportunity for improved follow-up of patients who are undergoing mechanical valve replacement. Studies have suggested that the ability to monitor the INR weekly at home results in improved maintenance of in-range values compared with a laboratory-based testing regimen3 and translates into a lower frequency of bleeding and thrombotic complications.⁴ Furthermore, Schmidtke et al.⁵ have demonstrated that self-management of anticoagulation leads to a superior quality of life after mechanical valve replacement compared with conventional physician-monitored anticoagulation.

·    If a bioprosthetic composite valve was used, I do not prescribe warfarin, only aspirin.

·  An echocardiogram before discharge is helpful to ensure normal valve and myocardial function and to evaluate residual pericardial hematoma. As in any group of patients with an aneurysm or dissection, a significant number of patients may require subsequent operations for aneurysms elsewhere in the aorta. This reinforces previous observations indicating that conscientious postoperative follow-up of these patients is necessary.

·   The practice of monitoring patients with an annual CT scan or MRI is necessary when an aneurysm has been resected, especially for the first 2 years. Subsequently, every other year is sufficient.

·  Bentall failures are rare during long-term follow-up. The Bentall technique is safe and durable, with a low incidence of postoperative complications in a population with disease of the ascending aorta and aortic valve.

·    The lower frequency of reoperation is a major advantage compared with the results of valve- sparing approaches, in which significant AI develops in a variable proportion of patients.

·  Because the Bentall operation is associated with excellent short- and long-term results, aggressive use of this procedure is appropriate if aortic valve surgery is necessary in a patient with even mild (4.5 cm) ascending aortic dilation.

·  The Bentall operation is considered the standard procedure against which to measure the outcomes of newer valve-sparing approaches to aortic root disease.

Step 5. Pearls and Pitfalls

·    “Cut well and sew well and the patient will do well.”

·    “The right operation, for the right indication, that is well executed helps ensure clinical success.”

·    Preoperative planning is very important. Understanding the extent of the pathologic process involving the valve, aorta, and coronary arteries is essential. Three-dimensional reconstructions of the aortic contrast-enhanced CT scan or MRI provide very helpful information.

·    Proper creation and mobilization of the coronary buttons will prevent kinking and twisting. If the coronary arteries are adequately mobilized, especially the right coronary artery, and the ostia do not reach the graft, the Cabrol technique is useful, especially in redo operations. Endocarditis and other inflammatory diseases involving the base of the aortic root are situations in which adequate mobilization of the arteries may not be possible.

·    Secure suturing of the valve to the annulus is essential. This anastomosis cannot be tested. Any leaks under the left or right coronary arteries are impossible to visualize if a repair suture is necessary. This is why I use 3-0 running Prolene sutures from the residual aorta to the valve sewing cuff after tying the valve-interrupted sutures.

·    The graft should be distended with cardioplegia to test the left coronary anastomosis after it is performed, because this is a location that will be difficult to visualize later. With the graft distended, the length to the distal aorta can be determined. I perform the distal end-to-end anastomosis and redistend the graft with cardioplegia to determine the exact location for the right coronary anastomosis accurately. This technique, along with proper mobilization of the right coronary, prevents technical errors that could lead to inadequate flow through the coronary artery.

·    Do not leave the operating room without achieving good hemostasis.

References

1.      Bentall H, De Bono A. A technique for complete replacement of the ascending aorta. Thorax. 1968;23:338–339.

2.      Kouchoukos NT, Wareing TH, Murphy SF, Perrillo JB. Sixteen-year experience with aortic root replacement: results of 172 operations. Ann Surg. 1991;214:308–320.

3.      Rosengart TK. Anticoagulation self-testing after heart valve replacement. J Heart Valve Dis. 2002;11(suppl 1):S61–S65.

4.      Kortke H, Korfer R. International normalized ratio self-management after mechanical heart valve replacement: is an early start advantageous? Ann Thorac Surg. 2001;72:44–48.

5.      Schmidtke C, Huppe M, Berndt S, et al. Quality of life after aortic valve replacement: self-management or conventional anticoagulation therapy after mechanical valve replacement plus pulmonary autograft. Z Kardiol. 2001;90:860–866.