Background
Among congenital aortic valve anomalies, quadricuspid aortic valve (QAV) is rare relative to the more common bicuspid aortic valve lesion. More than half of these patients need valve surgery in adulthood mainly due to progressive aortic regurgitation. Here, we present two cases of QAV with one surgical patient, and the other non-surgical.
Discussion
A normal aortic valve is composed of three symmetric cusps. Abnormal cusps may be formed as a result of a developmental anomaly during embryological arterial trunk septation. The most common type of aortic valve deformation is the bicuspid valve, followed by unicuspid valve. QAV is very rare and it is also less common than quadricuspid pulmonary valve [
1]. QAV was reported to have an incidence of around 0.013~0.043% according to autopsy results [
2]. QAV also accounted for 0.55~1.46% of aortic valve surgical patients [
3,
4]. In our center, these two patients were the only two in the last six years.
Before echocardiography was widely used three decades ago, most QAVs were diagnosed during surgery or autopsy [
1] and seldom by aortography [
5]. In recent years, the majority of QAV patients were diagnosed by non-invasive methods, with echocardiography being the most popular. On short axis view, QAV has an “X” shape in diastole, instead of a normal “Y” pattern (as shown in Figure
3B). Since transesophageal echocardiography is now widely used, we can get better images than by using transthoracic echocardiography [
6,
7]. Computerized tomography and MRI also serve as alternative diagnostic methods [
8‐
10]. Unfortunately, we did not perform TEE preoperatively for the surgical patient in this study, because we were already sure about the QAV diagnosis, which was confirmed later both by computer tomography and inspection during the operation.
According to the anatomy of the four cusps, Hurwitz and Roberts categorized QAV into seven subtypes (A to G) [
11]. The two most frequent types are type A (four equal cusps) and type B (three normal cusps with one smaller cusp). It is thought that type B has a greater probability of developing aortic regurgitation because of the asymmetric shear stress of the cusps. Our first case belonged to type B with severe aortic insufficiency, while the second case was type A. Recently, Jagannath et al. summarized a detailed literature review and simplified the classification of QAV (type I to type IV) [
12]. Type I and type II are the same as the previously described types A and B.
Unlike the relatively stable quadricuspid pulmonary valve anatomy, more than half of QAV patients developed aortic regurgitation progressively with aortic stenosis seldom seen. Most of them need surgery in their fifties to sixties [
12]. Except for the possible subsequent lesion of aortic regurgitation, some QAVs are often associated with other abnormalities, such as displacement of the coronary sinus and ostium, ventricular septal defect, patent duct arteriosus, subaortic stenosis, cardiomyopathy, valsalva aneurysm, and mitral valve regurgitation [
13‐
15]. Although Jagannath et al. indicated that aortic root dilatation was rare in QAV patients in their latest review, aortic root aneurysm might occasionally occur, as in our case and also reported by others [
16‐
18]. This may be a result of long-term aortic regurgitation. Left ventricular dysfunction was also occasionally seen in some cases, and the surgical outcomes for those cases were satisfactory [
19,
20], as seen in our first patient who had low ejection fraction pre-operatively but recovered well with temporary assistance of an intra-aortic balloon pump.
The surgical indication of QAV patients depends on the extent of aortic regurgitation and its associated lesions. For aortic regurgitation, the indication is almost the same as regurgitation caused by other reasons, such as degenerative disease. However, surgeons should pay attention to the origin of the coronary artery, and avoid injury when operating. As aortic valve repair is still a big challenge for cardiac surgeons, valve replacement was the most widely used operation in such patients. Some surgeons have tried tri-cuspidized or bi-cuspidized repair techniques and obtained good short-term results [
9,
21‐
23]. These patients can avoid complications associated with valve replacement, but long-term follow up is required.
Conclusions
In summary, we presented two cases of QAV in this paper. The first patient had severe aortic regurgitation resulting from a quadricuspid aortic, along with mitral regurgitation and ascending aorta dilatation. The second was a non-surgical asymptomatic young patient. With the advancement of echocardiography and multi-detector computer tomography, QAV has been diagnosed more accurately and promptly in recent years. Valve replacement or repair is needed at appropriate time in patients with progressive aortic regurgitation.
Competing interests
The authors declare that they have no competing interests.
Authors’ contribution
JZ and JZ collected the data and prepared the manuscript; SW performed and provided the ECHO data; YZ, FD, and JM operated on the patient and revised the manuscript. All authors read and approved the final manuscript.