16.1.2 Aortic Valve Repair/Replacement for Bacterial Endocarditis

Aortic valve endocarditis in patients with persistent or residual VSD tends to cause sepsis and hemodynamic instability. Moreover, the threat of cerebral and systemic embolization adds to the patient’s precarious condition. Patients often present with previous cerebral embolization, which challenges the operative decision because the anticoagulation required for the reparative operation could cause an extension of the embolic stroke. Experienced decisions and solutions guide the surgeon in the timing and performance of an operation that is life-saving and preserves patient well-being.

Endocarditis affecting the aortic valve in patients with congenital heart disease represents an anatomic continuum of conditions. Decisions may be guided by echocardiography but more often require immediate judgment based on the operative findings. When the infection is confined to one leaflet, reparative operations have been described that involve biologic patch repair of a hole when the periphery of the leaflet is intact. Further destruction of the valve leaflets require valve replacement, provided that the annulus is preserved and holds sutures for the implant. When the infection is severe, it can extend into the annulus and subannular area to form an abscess. These conditions require careful consideration, as the reparative process may involve neighboring valves and interventricular muscle debridement.

Figure 16.5 shows a patient with aortic valve endocarditis who has undergone aortobicaval cardiopulmonary bypass, left ventricular venting, cardioplegic arrest (retrograde cardioplegia), and aortic exposure. The aortic valve leaflets have been resected, and a subannular abscess is noted below the orifice of the left main coronary artery. This pathologic condition significantly challenges the reparative solution that is necessary to obliterate the infection, implant a suitable valve, and prevent recurrence. Such abscesses may involve the septal muscle (heart block), the adjoining annulus of the mitral valve (mitral regurgitation), and the perimembranous area, which, if eroded and perforated, can cause left ventricular to right atrial shunting.

Subaortic annular abscesses are debrided and covered with biologic patches, using running suture technique as shown in Fig. 16.6. The bioprosthetic or mechanical valve can then be placed using the implanted pericardial patch as a neoannulus to anchor the implanting sutures, as noted in Fig. 16.7. Often, the annular and proximal aortic destruction are severe enough that extensive annular and aortic resection is necessary (Fig. 16.8) in preparation for patch abscess obliteration and a Bentall operation with coronary artery reimplantation, as seen in Fig. 16.9. Another related solution for a subannular abscess is to use an aortic homograft with the attached mitral leaflet as an apron to cover the annular abscess while anchoring the homograft in place. Figure 16.10 shows the annular debridement and coronary button mobilization. Figure 16.11 shows how the homograft can be implanted with eventual coronary button attachment to complete the repair.

When the infection process involves the annulus near the interventricular septum, other extensive solutions are necessary, based on the Konno operation that was introduced to treat severe left ventricular outflow tract obstruction. The inset in Fig. 16.12a shows the proposed incision that exposes the aorta, the right ventricle, and the left ventricle. Figure 16.12b illustrates the result of extensive aortic annulus and interventricular muscular septal debridement. Figure 16.13 demonstrates how the mitral valve apron is oriented and used to replace the resected muscle as an outflow tract patch. Care must be taken to suture this apron to viable muscle, to prevent disruption and residual VSD. The suturing is very close to the conduction system and could cause heart block. Though it is important to avoid this complication, it is better to reconstruct the outflow tract and secure aortic competence with the homograft than to be overly concerned about the high possibility of heart block. A transvenous dual-chamber pacemaker ameliorates the problem if it occurs. Once the neoaorta is implanted, a right ventricular patch is needed to prevent right ventricular outflow tract obstruction. Figure 16.14 shows the patch in place after successful separation from cardiopulmonary bypass.

Mitral/aortic annular involvement also requires well-placed biologic patches to obliterate the abscess and repair the anterior leaflet of the mitral valve. The same biologic patch can be applied to the membranous septum, although the exposure requires right atrial entry to complete the repair. The native VSD requires pericardial patch closure using interrupted suture technique.

The best solution for aortic valve replacement in the young adult with congenital heart disease and aortic valve endocarditis not amenable to repair is the Ross operation. The Ross operation has the obvious benefits of an autologous graft, which include excellent hemodynamics, bacterial resistance, and freedom from warfarin anticoagulation. The principles and techniques of this operation do not vary from the usual indications of left ventricular outflow tract obstruction and are described in Chap. 14. Before this operation is contemplated, however, the surgeon must ascertain that there is a well-defined subpulmonic muscular conus that will allow autograft implantation into the left ventricular outflow tract. Patients with doubly committed VSDs or with VSDs that extend to the pulmonary annulus will not have a well-defined subpulmonic muscle ring that is necessary for aortic implantation. These patients are therefore better treated by other methods such as aortic homografts or free-style heterografts.

Alternatively, a simple aortic valve replacement can be performed using a bioprosthetic valve, assuming that the valve annulus is not destroyed and can hold sutures for proper device implantation. In the case of a destroyed annulus, a valved conduit can be constructed using a bioprosthetic valve implanted or sewn into a graft, which can be used to perform a Bentall operation with reimplantation of the coronary arteries as noted above.

Aortic valve endocarditis can also involve the mitral valve and requires concomitant mitral valve repair or replacement. Solutions to this problem include anterior leaflet repair and bioprosthetic mitral valve replacement.

16.1.3 Mitral Valve Repair/Replacement for Bacterial Endocarditis

Mitral valve endocarditis, like aortic valve endocarditis, presents in myriad ways that may call for repair by conservative or replacement techniques. Figure 16.15 shows vegetations emanating from the posterior mitral valve leaflet. This situation is favorable for repair; a careful resection and debridement can result in mitral valve repair by leaflet sliding valvuloplasty-annular ring techniques. Figure 16.16 shows the hole in the posterior leaflet that was caused by the resection and debridement. The suture is being placed to institute a sliding valvuloplasty that, when completed, can be reinforced by an annular ring. Figure 16.17 shows the completed repair with the implanted annuloplasty ring.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. of the Aorta in Adulthood
2. Aortic Aneurysms
3. Ventricular Outflow Tract Obstruction in the Adult
4. Fontan, 1½ Ventricular Repair, and Fontan Conversion Operations in Adults

Stay updated, free articles. Join our Telegram channel

Join