Surgical Treatment of Patients with Aortic Valve Disease in Association with Atrial Fibrillation

Abstract

The frequency of atrial fibrillation development in patients with severe aortic valve stenosis ranges from 4 to 30%. This arrhythmia significantly worsens patients’ long-term survival. Currently, it is considered that performing ablation of arrhythmogenic myocardial areas during valve surgery does not impact in-hospital mortality and does not lead to prolonged hospital stay. According to modern recommendations, this procedure should be performed in all patients diagnosed with atrial fibrillation if the pericardium is opened. There are numerous ablation protocols available. For patients with isolated aortic valve disease, there is no need to open the atria during ablation. For the majority of patients with persistent atrial fibrillation, isolating the posterior wall of the left atrium, including the pulmonary vein areas, is sufficient. This article proposes an original approach to the combined treatment of valve disease and arrhythmia using the Perceval-S sutureless valve and the Gemini-S clamp-ablator. This approach reduces the time of cardiopulmonary bypass, which can benefit high-risk surgical patients.

1. Introduction

Atrial fibrillation (AF) is a common arrhythmia, affecting around 1–2% of the general population. The prevalence increases with age, reaching approximately 5–15% in individuals over 80 years [1]. Aortic valve disease, including aortic stenosis and aortic regurgitation, has reported a prevalence of around 0.5–1% in developed countries, increasing with age [2].

Aortic stenosis narrows the aortic valve opening, limiting blood flow from the left ventricle to the aorta. It is primarily a disease of aging caused by calcific degeneration, and it is the most common valvular heart disease in developed countries. The prevalence of AS in the elderly population (≥75 years) is estimated to be between 2.8 and 4.6% [3]. On the other hand, aortic regurgitation, the leaking or backflow of blood through the aortic valve, can be caused by various conditions, including aging, hypertension and endocarditis. The prevalence of moderate to severe AR in the general population is estimated to be around 0.5% [4].

The co-occurrence of AF and aortic valve disease is not uncommon because there are shared risk factors [5]. Research suggests that AF occurs in approximately 4–30% of patients with severe aortic stenosis, depending on the study population and diagnostic methods [6]. AF is also associated with poorer outcomes in patients with aortic valve disease, including increased mortality and morbidity [7]. AF in the context of AS is associated with a higher risk of stroke and systemic embolism, which significantly complicates the management of these patients [7]. The epidemiology of AF in patients with AR is less researched. However, given the shared risk factors, it is not uncommon to see these conditions together. AF in AR patients is also associated with worse outcomes, similar to AS patients [8].

However, specific epidemiological data for the combination of AF and aortic valve disease is limited and further research is needed to understand this patient population better.

Managing patients with AF and aortic valve disease is complex and requires a multidisciplinary approach. Therapeutic strategies often involve a combination of rate or rhythm control, anticoagulation and valve intervention [8].

In the 1980s, several scientists developed surgical methods for treating atrial fibrillation. Williams proposed a procedure for isolating the left atrium [9]. However, this method showed its effectiveness mainly in the “left atrial” form of atrial fibrillation, leaving other forms less responsive to the procedure [10]. Guiraudon introduced the “Corridor” procedure, which involved the surgeon isolating the impulse conduction path from the sinoatrial node to the atrioventricular [11]. Despite its promise, the procedure was limited in restoring an adequate ventricular response to the sinus node’s operation, while the atrial myocardium continued to contract asynchronously [12]. Both procedures could not comprehensively address three main challenges of arrhythmia: asynchronous contractions of the atria and ventricles, an inadequate ventricular response to stimulation, and blood stagnation in the atria [13]. Consequently, patients remained in the high-risk group for thromboembolic complications.

In 1987, Cox, based on electrophysiological studies and animal experiments, identified “macro-reentry” waves and established their size and the duration of circulation in a specific place of the atria [14]. This discovery led to the development of the “Labyrinth” procedure, which created a single path for the impulse from the sinus node to the atrioventricular by cutting and sewing the atria, thereby interrupting the circulation of the “macro-reentry” wave while preserving the activation of atrial tissues by the sinus node [15]. The first operation on a human heart took place on September 25, 1987, ultimately allowing the patient to avoid arrhythmia and the intake of antiarrhythmic drugs for 20 years [16].

The maze procedure had its drawbacks due to a high risk of complications. One of the lines in the surgical schema was situated near the sinus node, disrupting fibers responsible for the stress-induced response [17]. Another line blocked the Bachmann’s bundle, significantly impairing interatrial conduction [18]. The procedure was carried out exclusively under conditions of artificial circulation, accompanied by a corresponding amount of complications [19].

For these reasons, the procedure was modified and technically simplified over the following decade. At a median observation period of 5.4 years, sinus rhythm was maintained in 97% of patients’ post-surgery [20]. However, the procedure remained technically challenging, not easily accessible for mastering, and still accompanied by high perioperative risk [21]. These factors laid the groundwork for exploring energy sources that would allow the creation of ablation lines without cutting atrial tissue and for seeking ways to minimize surgical access [22]. In 1996, after accumulating experience from over 200 variously modified maze procedures, the authors performed the first operation on isolated AF, utilizing cryoablation technology to create patterns that disrupted the circulating “macro-reentry” waves [23]. The operation time was significantly reduced, and cryoenergy simplified the procedure [24]. Around the same time, experiments were conducted with other energy sources, such as radiofrequency and microwave [25]. These various energy sources used to achieve transmural lesions of the atrial myocardium following the original procedures pattern formed the basis for creating its fourth modification, the “Maze-IV” [26]. Radiofrequency energy gained the most widespread adoption [27].

Currently, according to guidelines from the European Association for Cardiothoracic Surgery (EACTS), cardiac procedures, including ablation, are divided into two categories: primary open atrial operations and primary closed atrial operations. Aortic valve replacement surgery and coronary artery bypass surgery are classified as the second type [28].

The optimal protocol for radiofrequency ablation (RFA) during aortic valve surgery is a subject of ongoing research debate. There are multiple approaches to consider, each with its benefits and drawbacks. The decision to perform an entire maze-IV operation or a non-maze procedure pulmonary vein isolation (PVI), Box-Lesion and variations (PVI) without atrial incision depends on patient-specific factors.

The maze-IV procedure is the most complex form of surgical ablation for AF. It involves creating a “maze” of lesions in the atria, effectively interrupting the abnormal electrical pathways. The reported success rates are high, with up to approximately 80% of patients free from AF 1 year post-operatively. However, the procedure is time-consuming, and it carries risks of complications such as bleeding and pacemaker dependency [29]. The limitation of this procedure is using two types of ablation devices to achieve the full line protocol of the original procedure [30]. Ablation requires the use of monopolar devices, which cannot always create a homogeneous lesion line. If the mitral line of the maze procedure is incomplete, these partial lines can result in peri-mitral atrial flutter. Performing a complete maze procedure is only possible by using cryosurgery [31]. On the other hand, a PVI procedure without atrial incision is a less invasive procedure that involves using the radiofrequency bipolar clamp to create lesions around the pulmonary veins, thereby isolating them electrically and preventing AF. The significant advantage of this procedure is its simplicity and shorter operative time, which translates into less surgical risk. However, the success rate is generally lower than the full maze procedure, particularly in patients with persistent AF [32]. Oral et al. demonstrated that complete PVI might not be sufficient in all AF patients, suggesting that non-PV foci can contribute to AF in these individuals [33]. Other studies have extended these findings and identified additional trigger sites within the left atrium, including the posterior wall, the left atrial appendage, and the coronary sinus [34]. For these reasons, all patients with persistent atrial fibrillation should undergo isolation of the posterior wall of the left atrium (BOX-Lesion), including the orifices of the pulmonary veins. Resection of the left atrial appendage makes it possible to form an additional line passing from the ridge zone to the collector of the left pulmonary veins [35].

The decision between the three procedures should consider the patient’s individual characteristics, including the type and duration of AF, left atrium volume index (LAVI), the patient’s overall health status, and the risk of surgical complications. For example, in younger, healthier patients or those with persistent AF, an entire maze-IV operation may be more beneficial despite its invasiveness. On the other hand, for older patients, those with significant comorbidities or those with paroxysmal AF, a PVI procedure without atrial incision may be preferable due to its lower surgical risk.

The optimal protocol for RFA during aortic valve surgery with AF is a tailored approach that considers the patient’s characteristics and balances the potential benefits of AF elimination against the procedure’s risks. Maze-III and non-maze procedures (PVI, Box-Lesion) without atrial incision have their place in the treatment of AF, and the choice between them should be made on a case-by-case basis.

2. Aortic valve replacement and radiofrequency isolation of the posterior wall of the left atrium in a high surgical risk patient: How we do it

Patients with aortic stenosis and atrial fibrillation who are considered to be at high surgical risk typically exhibit a range of clinical features and comorbidities. Here are some of the key factors that are often considered when determining surgical risk:

1. Advanced age: Older patients are often considered at a higher surgical risk due to the increased likelihood of comorbidities and reduced physiological reserve [36].

2. Severe comorbidities: Conditions such as severe pulmonary disease, chronic kidney disease, and liver disease [37].

3. Frailty: This includes factors such as cognitive impairment, reduced mobility, malnutrition, and dependency in activities of daily living [38].

4. Left ventricular dysfunction: A reduced left ventricular ejection fraction (LVEF) can increase surgical risk [39].

Cardiopulmonary bypass (CPB) duration plays a significant role in the outcomes in this group. The length of CPB has been linked with several potential complications, including organ dysfunction, postoperative bleeding and increased mortality. A study by Ranucci et al. demonstrated that CPB duration is an independent predictor of overall mortality and major complications following cardiothoracic surgeries [40]. According to their analysis, every additional 10 minutes of CPB increases the risk of overall mortality by 16%, the risk of significant complications by 18%, and the risk of postoperative bleeding by 12%. An article by Gansera and colleagues (2007) emphasized that CPB duration is associated with the risk of postoperative renal dysfunction and thrombocytopenia [41]. This finding reinforces the importance of minimizing CPB time in aortic valve replacement surgeries. In another study by Raja and co-authors (2005), CPB duration was an independent risk factor for developing postoperative acute lung injury [42].

In order to reduce the duration of cardiopulmonary bypass in such patients, we employ the Perceval-S sutureless valve, Box-Lesion radiofrequency ablation protocol with an additional line in the Ridge zone, and Marshall ligament destruction. The Perceval-S valve is an artificial valve made from bovine pericardium, implanted within a self-expanding nitinol frame that secures the valve in the implantation site. The valve is stored in an antibacterial solution, eliminating the need for pre-rinsing. The valve implantation involves three guiding sutures, which are subsequently removed. These factors combined allow us to achieve a myocardial ischaemic time of 15–18 minutes. Along with ablation and left atrial appendage occlusion, the total duration of cardiopulmonary bypass in our clinic for such procedures averages around 40 minutes.

Indications for the implantation of the Perceval-S prosthesis:

1. Age over 65 years.

2. Aortic valvular stenosis or a combination of stenosis with insufficiency with a fibrous ring size of 19–27 mm.

3. Aortic valvular insufficiency with fibrous ring size 19–27 mm.

4. Infective endocarditis without violation of the integrity of the fibrous ring and the configuration of the aortic root.

It should be noted that the main contraindications for using the valve are aortic root dilation and disruption of the fibrous annulus integrity. Many surgical teams have successfully used Perceval-S in cases of bicuspid aortic valve.

3. Operation

The first step involves the Box-Lesion ablation procedure. For RFA, we used a Cardioblate Gemini-S ablative device. The procedure is performed under parallel cardiopulmonary bypass due to hemodynamic instability during pulmonary vein occlusion. The right atrium is cannulated with a two-stage cannula. The aorta is cannulated as high as possible from the sinotubular ridge. After initiation of cardiopulmonary bypass using a dissector and forceps, the connective tissue in the area of the transverse sinus is separated by a blunt manoeuvre between the superior right pulmonary vein and the superior vena cava, and the inferior vena cava is mobilized. For the convenience and safety of bipolar clamp-ablator placement, we utilize specialized guides that minimize the risk of damaging surrounding anatomical structures. The guides are inserted similarly to the “Galaxy” procedure (Figure 1) [43]. The first guide is passed through the transverse sinus and removed behind the left atrial appendage. The second guide is passed through the oblique sinus of the pericardium between the inferior vena cava and the right inferior pulmonary vein. Since the ablation clamp and guidewires have a flexible structure, there is no need to rotate the heart at this stage. Next, the Cardioblate Gemini-S electrode is attached to the guidewires, and the electrode branches are introduced into the oblique and transverse sinuses of the pericardium on the left side to perform ablation of the left pulmonary veins and the posterior wall of the left atrium (Figure 2). The ablation of the right pulmonary vein orifices and the posterior wall of the left atrium is performed similarly (Figure 3). To create complete lines, we perform about 10 applications lasting about 10 minutes on each side. After completion of the ablation of the left atrium posterior wall, it is mandatory to perform an Exit-block test. Gemini-S electrodes allow ablation of the entire posterior wall of the left atrium as a single block according to the “box-lesion” scheme in the minimum amount of time (Figure 4). Additionally, the infusion of physiological solution into the clamp branches enables conducting ablation without charring the myocardium.

Figure 1.

Flexible guides in pericardial cavity. (A) Ascendence part of the aorta, (B) right atrium canula, (C) flexible guides, (D) superior right pulmonary vein, and (E) inferior right pulmonary vein.

Figure 2.

Performing left-side ablation.

Figure 3.

Performing right-side ablation.

Figure 4.

Final ablation scheme. Trasmural injury marked with a blue line.

The second step involves a prosthetic implantation. Carbon dioxide gas insufflation is carried out into the surgical wound to prevent air embolism. Valve implantation is typically performed in a single session of blood cardioplegia. During the implantation of a sutureless valve, the aortotomy should be performed approximately 3–3.5 cm above the coronary artery ostia to ensure a safe aortotomy closure at the end of the procedure without interfering with the upper edge of the valve frame. After decalcification, we leave a rim of approximately 3 mm and provide valve sizing. We do not open the specific size of the prosthesis until we evaluate the patient’s valve and measure its fibrous annulus. It is worth noting that a fibrous annulus larger than 27 mm is a contraindication for valve implantation.

After valve sizing, the prosthesis is prepared on a separate surgical table. The valve must be loaded into the delivery system to accomplish this. A valve holder and a collapser are set up on the stand (Figure 5). The collapser compresses the valve on the holder. In this state, the valve is presented to the operating surgeon (Figure 6).

Figure 5.

Perceval-S fixed in collapser.

Figure 6.

Perceval-S prepared for implantation. (A) Valve prosthesis, (B) sheath, (C) smart clip, and (D) handle of the holder.

Following decalcification of the valve and preparation of the prosthesis for implantation, we proceed with suture occlusion of the left atrial appendage. At this point in the operation, creating an additional ablation line connecting the Ridge zone and the left pulmonary vein collector is possible. In patients with persistent atrial fibrillation, we disrupt the adipose tissue in the Waterston’s groove area and perform ablation of this zone with a Cardioblate MAPS monopolar electrode. Then we proceed with aortic valve implantation. Guiding sutures are sewn in the nadir of the leaflets. Incorrect distribution of guiding sutures can lead to the formation of paravalvular fistulas.

The sutures are passed through the valve ears (Figure 7). The valve is positioned at the fibrous annulus. The lower portion of the valve is opened first, followed by the upper portion. This sequence of unfolding allows us to verify the correct positioning of the lower part while it is still visually accessible. After unfolding the upper part, any changes in the prosthesis position can only be made through explanation of the prosthesis. After removing the holder, the position of the prosthesis relative to the fibrous ring and coronary artery ostia is visually evaluated (Figure 8). The final step of the implantation is balloon dilation, inserted into the valve lumen to a pressure of 4 ATM for 40–60 seconds. During this process, warm physiological saline is used to irrigate the valve frame for complete expansion of the nitinol frame. The main stage of the operation concludes with the formation of a double-row suture on the aortotomy. At this stage, it is critically important to visualize each suture to avoid capturing the prosthesis frame in the suture.

Figure 7.

Fixation of the guide sutures.

Figure 8.

Perceval-S implanted in aortic root.

4. Features of perceval-S prosthesis implantation in bicuspid aortic valve

Bicuspid aortic valve can pose a significant challenge during the implantation of a sutureless valve. The most common variants encountered are Sievers 1 or 2. Abnormal distribution of leaflets and commissures around the fibrous annulus circumference may lead to improper positioning of guiding sutures. Improper positioning of the valve frame can result in the formation of paravalvular fistulas. It is also essential to pay attention to the coronary artery ostia, which may have non-standard origins.

For correct valve seating, it is necessary to create guiding sutures around the circumference at points of 120–120-120 degrees and pre-calculate the position of the valve struts relative to the coronary artery ostia. The valve should not be implanted in case of aortic root dilatation. Isolated dilation of the ascending aorta above the sinotubular ridge is not a contraindication for implantation.

5. Conclusion

Performing ablation in patients with a concomitant correction of aortic valve disease is not associated with increased in-hospital mortality, more frequent pacemaker implantation or neurological complications and is indicated for all patients diagnosed with arrhythmia. Combined open procedures show significantly better long-term outcomes than isolated transcatheter aortic valve implantation in elderly patients with low surgical risk and persistent atrial fibrillation. An analysis conducted by William L Patrick et al. demonstrates reduced mortality, pacemaker implantation rates, and hospitalizations due to decompensated heart failure in the long-term period for patients who underwent arrhythmia correction and prosthetic valve replacement under cardiopulmonary bypass, compared to the transcatheter aortic valve implantation group (TAVI) group where ablation was not performed [44].

We again emphasize that the choice of ablation protocol depends on the form of atrial fibrillation, the patient’s atrial size, and concomitant pathology. According to the authors, the ablation protocol presented in this chapter is appropriate for most clinical situations.