**2. Balloon valvuloplasty vs. surgical valvulotomy**

The debate of whether balloon valvuloplasty or surgical valvulotomy is the superior initial management for aortic stenosis remains controversial. In balloon valvuloplasty, it is imperative to balance reducing the aortic valve gradient while limiting the amount of aortic regurgitation produced [1]. The challenge interventionalists face is having to make the decision of leaving a patient with residual aortic stenosis (AS) or acute aortic regurgitation (AR) when an ideal outcome is not possible. Both outcomes can pose as risk factors for poor long-term results and further reinterventions [2]. On the other hand, surgical valvulotomy for aortic stenosis is an emerging approach with continuous technique improvements to decrease mortality. However, it is not offered at many institutions as it can be technically challenging, especially for neonates. Hence, it is important to analyze the outcomes for both techniques in terms of the age of presentation – critical neonatal aortic stenosis vs. noncritical aortic stenosis.

#### **2.1 Critical aortic stenosis of neonates**

Patients under one month of age with aortic stenosis are classified as having critical neonatal aortic valve stenosis [1]. These patients are usually symptomatic, ductal dependent for survival, and have other associated cardiac congenital anomalies [3]. Most patients will have a smaller valve annulus with either a bicuspid or unicuspid aortic valve, although many are too dysplastic to differentiate [1, 3].

Balloon valvuloplasty has been the preferred method for the management of critical neonatal aortic valve stenosis for many decades. When balloon valvuloplasty is performed on patients with bicuspid or unicuspid valves, the tendency to cause a tear in the fused leaflet is high, causing prolapse of the leaflet, regurgitation, and a need for further intervention [4]. Hence, improvements in surgical valvulotomy techniques have raised the question of which is the superior management option for this patient population.

Donald et al. reviewed literature comparing the outcomes of both approaches in neonates and concluded that mortality is higher for balloon valvuloplasty (56%) compared to surgical valvulotomy (19%). They also concluded that undergoing either procedure during the neonatal period is a risk factor itself for poor outcomes [5]. A similar conclusion was reached by Siddiqui and colleagues who reported that for the group who underwent surgical valvulotomy, freedom from reintervention at 10 years for neonates and infants was 53.9% and 75%, respectively. Freedom from reintervention at 10 years for neonates who underwent balloon valvuloplasty was 17% compared to 50% in infants. They further reported that besides balloon valvuloplasty and age < 1 month, other factors associated with reintervention include unicuspid valve morphology, presence of endocardial fibroelastosis and presence of an atrial

#### *Advances in the Management of Congenital Malformations of the Aortic Valve DOI: http://dx.doi.org/10.5772/intechopen.105641*

septal defect [6]. Zain et al. compared both approaches by performing a retrospective analysis on 25 neonates who underwent both balloon valvuloplasty and surgical valvulotomy. The majority of patients had a bicuspid aortic valve morphology, and one patient had unicuspid aortic valve morphology. Like the previous studies, they also concluded that patients who underwent balloon valvuloplasty had a higher reintervention rate. When comparing other long-term results like development of moderate to severe aortic regurgitation, balloon dilation was still the inferior option [7].

There are other studies that focused on the outcomes of balloon valvuloplasty mentioning neonatal intervention as a risk factor for mortality and high reintervention rates [1, 8–11]. However, many of these studies included patients before the year 1998, when the Norwood procedure was introduced. When excluding patients after the year 1998, mortality from balloon valvuloplasty decreased significantly. Another limitation that is not always mentioned in these studies, especially in retrospective studies, is that neonates who underwent balloon valvuloplasty tend to be more complex or ill at the time of intervention, hence resulting in a biased comparison [12].

Surgical repair techniques for aortic stenosis can range from a simple blade commissurotomy, to leaflet reconstruction with pericardial patches [13]. Although techniques for the repair of critical neonatal aortic stenosis are evolving, this approach is not adopted at many centers and most still prefer balloon valvuloplasty as the initial palliative method of choice [14]. In patients with tricuspid aortic valve morphology, most repairs consist of a simple blade commissurotomy where the extent of repair is largely within the surgeons' control [7, 15], unlike balloon valvuloplasty which is a blind technique, and the degree of damage is unknown at the time of intervention [7]. Some have argued that leaflet debridement should also be done for better long-term results during the surgical procedure [6, 14, 16]. For bicuspid and unicuspid aortic valves, surgical repair techniques are more complex as they can range from simple repairs or complete reconstruction of the aortic valve. Repair techniques will be discussed in a later section.

Alexiou et al. analyzed 18 neonates who underwent open valvulotomy for critical isolated aortic stenosis and concluded that operative mortality for surgical repair in this patient population has been decreasing over time as repair techniques improve. They performed simple commissurotomy to the aortic annulus and also excised obstructive nodules on the aortic valvular surfaces if present. Patients with bicuspid aortic valve morphology were not converted to tricuspid morphology. This study yielded excellent results where there was no early mortality and freedom from aortic reintervention was 85% at 5 years. However, the sample size was small and the study excluded patients with complex repairs [15]. Hraska and colleagues agreed with the previous study and stated that surgical valvulotomy in neonates can produce predictable and reliable long-term results for any valve morphology. They analyzed 34 neonates with various valve morphology and achieved a 100% freedom from aortic valve replacement at 20 years for patients with tricuspid valve morphology. They concluded that the underlying morphology and function of the LV are more important compared to the method of repair for determining outcomes. However, the long-term preservation of an acceptable function of the native aortic valve seems to depend on the method and the cusp anatomy. They believe that it is important to achieve tricuspid morphology in a dysplastic trileaflet valve during the repair for a better outcome, but valve reconstruction into a tricuspid morphology from a bicuspid or unicuspid morphology will not yield the same result [16]. Vergnat and colleagues adopted a 2-step approach for 103 neonates with critical neonatal aortic stenosis. It consists of leaflet remodeling and apparatus rehabilitation, and an attempt to achieve a tricuspid

arrangement without leaflet reconstruction. They also highlighted the importance of leaflet debridement, which is only possible with surgical repair, to preserve the native valve as balloon dilation resulted in early stenosis [14].

In summary, although preliminary results seem to favor surgical repair of critical neonatal aortic stenosis, there are many other factors to consider. Patients in this population are often very ill and require immediate intervention for survival. This would have contributed to the high mortality rate for balloon valvuloplasty. Additionally, in most studies where the surgical repair was possible, they usually consist of simple surgical techniques like commissurotomy and debridement. Complex repairs are technically demanding and rarely performed in neonates and infants. Therefore, a non-bias method is needed to accurately compare the two approaches. This will be difficult as every patient presents differently and will have specific needs [16]. In terms of replacement options in this population, the Ross−Konno procedure may be the only option because of the small aortic annulus [17]. The Ross procedure will be discussed in a later section.

#### **2.2 Noncritical aortic stenosis**

Patients who present after the neonatal period generally have fewer dysplastic valves and adequate aortic annulus size, making surgical repair more feasible [3, 18]. Similar to critical aortic stenosis, surgical repair seems to be preferred in this patient population.

Hill and colleagues performed a meta-analysis to compare both techniques and reported that most literature either determined surgical valvulotomy as the more superior method or found no difference between the two. The meta-analysis consisted of 2368 patients with mean age of 2.9 months. Overall, at 10 years, the survival rate was 87% for balloon valvuloplasty and 90% for surgical valvulotomy. There was a significant difference for freedom from reintervention at 10 years, with balloon valvuloplasty at 46% and surgical valvulotomy at 73%; however, no significant difference for freedom from replacement was found. In a subgroup analysis for infants <1 year of age, the results were similar and only differences for freedom of reintervention were found with balloon valvuloplasty at 40% and surgical valvulotomy at 60% [19].

Brown et al. also concluded that surgical repair is the superior option after performing analysis on 158 patients older than 2 months of age. They reported that the surgical method resulted in greater gradient reduction and significantly less regurgitation. There was also a longer interval for reintervention for the surgical approach [18]. Brown et al. performed a retrospective analysis on 509 patients who underwent balloon valvuloplasty and concluded that patients older than 11 years of age have an increased risk of developing moderate to severe aortic regurgitation after balloon valvuloplasty [20]. Hence, it appears there may be certain age groups where balloon valvuloplasty should be avoided to minimize the possibility of reintervention.

Overall, it appears that surgical repair is superior to balloon valvuloplasty for patients with noncritical aortic stenosis by comparing freedom from reintervention rates. However, without standardization for the definition of successful management, thresholds for reintervention and replacement, or ballooning and repair techniques, it is difficult to compare the two modalities accurately without biases in both critical and noncritical aortic stenosis patients. Furthermore, most studies cover a diverse age group, span over different amounts of follow-up time, or cover different time periods, making the comparison even harder [5, 11, 12]. Since each patient's anatomy, physiology, and age of presentation are different, the management plan should be tailored for

#### *Advances in the Management of Congenital Malformations of the Aortic Valve DOI: http://dx.doi.org/10.5772/intechopen.105641*

each individual to minimize complications [7, 9]. A successful outcome also depends on the options available and skills of the surgeons and interventionalists [9].

Balloon valvuloplasty has improved and become safer over the past decade [9]. Having a standardized progression may be helpful for this blind technique in minimizing complications. Porras et al. performed a study to investigate the utility of a Standardized Clinical Assessment and Management Plan (SCAMP) algorithm for the management of congenital aortic stenosis. They used the cut-off of ≤35 mmHg residual aortic stenosis and the degree of aortic regurgitation present after each ballooning to determine the option for further intervention. Following the algorithm, they managed to ensure that all patients achieve a final gradient of ≤35 mmHg without causing greater aortic regurgitation after the ballooning procedure [21]. However, it is worth noting that the study sample size only consisted of 23 patients and 92 controls, and follow-up duration was only 10 years.

There are other studies that agree with Porras et al. that acute residual aortic stenosis gradient and post-dilation aortic regurgitation were factors most strongly related to the decision for long-term aortic valve replacement [2, 10, 12, 20]. Rao and colleagues concluded that the most important factors leading to restenosis are immediate post-valvuloplasty aortic valve stenosis and patients ≤3 years of age at the time of procedure. They also commented that many studies found a linear relationship between follow-up time duration and post-procedural aortic insufficiency, however, no definite causative factors were found [12]. Brown et al. also concluded that a residual aortic stenosis gradient of ≤35 mmHg was associated with greater freedom from aortic valve replacement and stated that having a lower aortic stenosis gradient might be more important than ensuring minimal aortic regurgitation [20]. However, Sullivan et al. disagreed and reported that acute post-procedural aortic regurgitation is associated with a greater risk instead. They discovered that patients with moderate or severe acute aortic regurgitation post-procedure with residual aortic stenosis gradients <30 mmHg had three times greater long-term risk for aortic valve replacement compared to those with mild or less aortic regurgitation and > 30 mmHg residual gradient. However, they did note that the study population consisted of more neonates, and age could be a modifier [2].

Since reinterventions and replacement might be inevitable due to recurrent stenosis or progressive aortic regurgitation [11, 22], balloon valvuloplasty can be considered as an initial palliative option for ill patients [7, 11]. Zain et al. proposed that balloon valvuloplasty should be done for bicuspid valves with equal size leaflets, while surgery should be reserved for thick, nodular dysplastic valves or unicuspid valves with small aortic annulus to prevent the need for multiple interventions [7, 11]. Ballooning in highly dysplastic valves distributes circumferential force unevenly, causing tears in the weakest part of the aortic valve and may therefore disrupt the cusps unevenly leading to poorer outcomes [11, 18]. On the other hand, surgical repair allows for direct inspection of the valve where surgeons can have better control of the extent of commissurotomy and more precise repair [7, 15]. Nonetheless, repeat balloon valvuloplasty should still be considered as the first option in most patients after restenosis as it can still yield excellent results [12].
