Introduction
Heart valve infections are a quite uncommon pathology with an estimated annual incidence of 3–10 cases in 100,000 in a normal population. With a mortality standing between 15% and 30% (according to clinical circumstances and to the infective organism) [ , ], this pathology still remains a life-threatening disease that causes also significant morbidity.
As a result of the enormous progress made in terms of diagnosis and treatment, the epidemiological profile of infective endocarditis (IE) has changed in recent decades, as shown by the EURO-ENDO registry. According to the paper published by EURO-ENDO Investigators in 2019 [ ], nowadays IE more frequently affects older patients (predominantly male over 60 year of age) with comorbidities. Prosthetic valve IE, intracardiac device-related IE, nosocomial, staphylococcal, and enterococcal endocarditis are also more frequent.
Moreover, oral streptococcal endocarditis is less frequent, and its frequency has not increased since implementation of the 2009 and 2015 recommendations restricting indications for antibiotic prophylaxis. These considerations help to draw the contemporary profile of patients suffering from IE.
Endocarditis team
As described in 2015 Guidelines, the presence of an Endocarditis Team is strongly recommended in order to manage the complexity of this pathology [ ]. The Team is composed of cardiac surgeons, cardiologists, anesthesiologists, infectious disease specialists, microbiologists and, when available, specialists in valve diseases, congenital heart disease, pacemaker extraction, echocardiography and other cardiac imaging techniques, neurologists, and facilities for neurosurgery and interventional neuroradiology. Besides the intrahospital management of the patients, the Endocarditis Team should organize a correct assessment and follow-up in line with the very latest recommendations and participate in patient education program. As shown in the 2019 paper of Davierwala and colleagues, the Endocarditis Team approach facilitates early diagnosis, implementation of comprehensive therapeutic strategies and appropriate decision-making, which could potentially play an important role in reducing the high morbidity and mortality associated with this disease [ ].
Timing of surgery
It’s experts’ opinion that surgical treatment is necessary in approximately half of the patients suffering from IE, in order to prevent severe complications such as heart failure, uncontrolled infection, and embolism [ ]. In this context, all US and European guidelines are aligned on the indication of early surgery when surgery is needed [ , , ].
Early surgery means a surgery “during initial hospitalization before completion of a full therapeutic course of antibiotics” [ ]. Early surgery should be performed in IE with valve disfunction in order to prevent heart failure, in case of infection by multiresistant microorganisms ( Staphylococcus aureus , fungal, or others), in presence of abscess, heart block, or deep tissues destruction, and in case of a persistent bacteremia and/or fever longer than 5–7 days after onset of an appropriate antibiotic therapy. Other indications of early surgery are a vegetation larger than 1 cm, and recurrent emboli. In selected patients with large ad unstable vegetation, an emergency (within 48 h) surgery should be considered. In case of cardiogenic shock, an emergency surgery (within 24 h) could be performed [ ].
While in the abovementioned cases the recommendations are quite intuitive, there are some difficult scenarios that the Team has to deal with. In fact, symptomatic neurological events develop in 15%–30% of all patients with IE, and additional silent events are frequent. How to handle these situations? Evidence regarding the ideal time interval between stroke and cardiac surgery is inconsistent, but most recent data favor early surgery. If any significant cerebral hemorrhage has been excluded by radiological and clinical assessment and if neurological clinical state is not severely compromised, surgery should not be delayed and can be performed with a low neurological risk (3%–6%) and good probability of complete neurological recovery [ , ]. Contrariwise, patients with intracranial hemorrhage have worse neurological prognosis and surgery should generally be postponed for 2–4 weeks [ , ].
Planning surgical treatment
Preoperative analysis of the valve is a crucial requirement in order to choose the best surgical technique. Besides orienting the Endocarditis Team whether it’s time to perform the operation, transesophageal ultrasound assessment must also guide the surgeon to identify the appropriate surgical technique detecting vegetations, paravalvular involvement, and eventual underlying native valve degenerative/congenital disease [e.g., calcification, bicuspid aortic valve (BAV)]. Unfortunately, as described in the literature, the sensitivity of preoperative echo assessment in detecting abscess during IE is as low as 80.5% [ ]. The presence of abscess is a tricky and quite frequent condition for the surgeon. In fact, in our experience, an abscess was found intraoperatively in 43.9% of patients affected by native IE. In the case of a prosthetic IE, the percentage increases to 65.2% [ ].
Therefore, the definitive anatomical valve assessment and the consequent choice of the adapted surgical technique would be made after the surgical valve inspection.
Surgical techniques
Valve analysis and surgical debridement
Generally, the aortic valve is approached via full sternotomy, but limited sternotomy can be applied in simple IE case where infection is clearly limited to the atrioventricular (AV) leaflets. Careful evaluation of the AV and lesions is crucial. Typically, the full extent of the destructive process became evident only after careful debridement. In principle, if aortic valve repair is a considered option, resection of the infected tissue should respect any healthy valve and aortic tissues. In case of leaflet-limited infection, the evaluation should focus on the size of the defect, number of leaflets involved, and residual tissues quality. A perforation may clearly appear or it can also be covered by a vegetation.
Infective endocarditis limited to the valve
During the last 3 decades, numerous technsiques for AV repair have been described with encouraging mid- and long-term results [ , ]. Indications for AV repair have been extended even in the field of IE in specialized centers [ , , ] for selected young patients with limited valve lesions to avoid implantation of prosthetic material and to avoid the long-term complications of mechanical and bioprosthetic valve replacement.
Valve repair techniques in case of IE depend on lesion location and quantity/quality of remaining tissue. In IE, leaflet perforation is a frequent direct finding; if not, complete resection of the vegetation will generally create leaflet defect equivalent to a perforation. Ideally and to facilitate the repair, the surgeon should preserve a solid edge to the defect and especially, he should try whenever possible to preserve the leaflet free margin. The edge of the defect must be cleaned, leaving healthy tissues in order to be able to suture a patch. A direct closure of perforation can be performed in case of a very small defect (<3–4 mm). In rare situation, vegetation can be resected leaving a nearly normal valve where no other repair procedure is needed except perhaps an annuloplasty. In case of larger perforation, addition of a patch is the only option to repair the valve. As described previously by our group [ ], the technique to repair cusp perforation is to have the patch trimmed in a form resembling the present defect in shape and adding 2 mm to its size, so as to prevent restriction of the leaflet surface following patch implantation. The patch should be applied on the aortic surface of the cusp by running a continuous suture using prolene 5/0 or 6/0 as shown in Fig. 17.1 .
A good sizing of the patch is crucial; in fact, a too small patch may retract the leaflet and induce residual aortic regurgitation (AR) and too big patch will billow under the valve increasing the stress on the leaflet and the sutures. In our experience, we have used the different types of pericardial patches (e.g., xeno-pericardium, fresh or glutaraldehyde-treated autologous pericardium) with no observable difference among these material in term of repair durability [ ]. Since 2015, next to autologous pericardium, we used decellularized xeno-pericardial patch which promises better tissue remodeling and less calcific degeneration compared to the previous generation of xeno-pericardium [ ]. In our experience of AV repair with patch techniques, hospital and long-term survival rates are comparable to those reported for valve replacement in IE [ ]. Moreover, other similar publication supported the repair approach in selected patients, considering the good survival and the absence of reinfections [ , ].
Patch repair techniques also exist to correct defect of one commissure or defect including the leaflet free margin [ ]. However, these techniques are more complex as they recreate a free margin and their long stability is not proven. As the patch material will remodel over time, any retraction of the neo-free margin represents a risk to induce AR. For this reason, some expert advise against leaflet reconstruction with patch whenever the free margin is involved [ ]. Also, complete destruction of one leaflet or perforation of more than two leaflets will prompt us to abort valve repair in IE. After leaflet repair, an annuloplasty can in certain case be performed to enhance the valve coaptation. If annuloplasty is recommended to improve repair durability in AV repair for chronic AR because of annulus enlargement [ , , ], this recommendation is probably not applicable in acute AR due to IE where aortic annulus is generally of normal size. In active IE, annuloplasty is indicated when after leaflet repair an absence or a lack of central coaptation is observed. In these cases, two or three Cabrol annuloplasty stitches [ ] (also called, subcommissural annuloplasty) are performed using pericardial felt instead of Teflon to avoid prosthetic material. In healed IE operated for chronic AR, circumferential annuloplasty (i.e., external ring or valve sparing reimplantation) can be performed in case of annulus dilatation (>26 mm).
In active IE involving BAV, experience has taught us that valve repair is not a durable option [ , ] (see Fig. 17.2 ). Effectively, the combination of infectious lesions and lesions specific of BAV (conjoined leaflet prolapse, raphe fibrosis or calcification, annulus dilation, aortopathy) make a very complex situation to repair.
