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| REVIEW ARTICLE |
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| Year : 2022 | Volume
: 23
| Issue : 1 | Page : 47-54 |
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Diagnosis and therapeutic cardiac catheterization of symptomatic bicuspid aortic stenosis in the pediatric population
Haytham Yassin, Hesham Al-Saloos
Division of Cardiology, Heart Centre, Sidra Medicine, Doha, Qatar
| Date of Submission | 02-Mar-2022 |
| Date of Acceptance | 10-Apr-2022 |
| Date of Web Publication | 16-May-2022 |
Correspondence Address:
Dr. Hesham Al-Saloos
Division of Cardiology, Heart Center, Sidra Medicine, P. O. Box 26999, Doha
Qatar
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/heartviews.heartviews_39_22
 Abstract | | |
Bicuspid aortic valve (BAV) is the most common congenital heart disease with a prevalence of 0.5%–1.3% of the population. Many children with BAV are asymptomatic. Clinically relevant abnormal valve function usually occurs in adulthood. However, in rare cases, children can fail to thrive which requires valvular intervention. In this review, we will explore in more detail the anatomy of the BAV, clinical presentation of BAV, diagnosis of BAV, and its function by echocardiography, and indications for transcatheter intervention in the pediatric population.
Keywords: Anatomy, aortic stenosis, aortopathy, balloon valvuloplasty, bicuspid aortic valve, morphology
How to cite this article:
Yassin H, Al-Saloos H. Diagnosis and therapeutic cardiac catheterization of symptomatic bicuspid aortic stenosis in the pediatric population. Heart Views 2022;23:47-54 |
How to cite this URL:
Yassin H, Al-Saloos H. Diagnosis and therapeutic cardiac catheterization of symptomatic bicuspid aortic stenosis in the pediatric population. Heart Views [serial online] 2022 [cited 2023 Oct 3];23:47-54. Available from: https://www.heartviews.org/text.asp?2022/23/1/47/345325 |
| Introduction | |  |
Bicuspid aortic valve (BAV) is the most common congenital heart disease with a prevalence of up to 1.3%. It is more common in males than females with a ratio of 2.65:1.[1] Studies found a heritable component to BAV disease, a first-degree relative of patients with BAV has a high chance (up to 10%) of having BAV. Hence, screening echocardiogram for first-degree relatives is recommended.[2]
The fetal heart is developed by 8 weeks of gestation. The semilunar valves are developed by the division of the truncus arteriosus into two separate channels that eventually form the aortic and pulmonary trunks. A small swelling appears on the inferior margins of each trunk, forming the basis of the valve leaflets. The BAV is believed to be due to a fusion of the aortic cusps during valvulogenesis.[3] In this review, we will explore in more detail the anatomy of the BAV, clinical presentation, echocardiography, and indications for transcatheter intervention.
| Anatomy | | |
Normally, the aortic valve includes three cusps: right, left, and noncoronary cusps. In BAV, there are only two cusps and usually unequal in size. The inequality is due to the fusion of two cusps leading to one larger cusp with a presence of a central raphe or fibrous ridge.[4]
| Types of Bicuspid Aortic Valve | | |
There are multiple published classifications of BAV. Below is the classification from the International BAV Consortium [Figure 1]: | Figure 1: BAV morphology: (1) Type 1 BAV with complete raphe and asymmetrical as the noncoronary is smaller than the conjoined cusp. (2) Type 2 BAV with complete raphe and asymmetrical as the left cusp is larger than the conjoined cusp. (3) Type 3 BAV with complete raphe and asymmetrical as the right cusp is larger than the conjoined cusp. (4) Type 1 BAV but with complete raphe but symmetrical cusps size. (5) Type 1 BAV but with no raphe and symmetrical cusps size. (6) Type 1 BAV but with incomplete raphe and partially fused left and right cusps. L: Left cusp, N: Noncoronary cusp, R: Right cusp, BAV: Bicuspid aortic valve
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- Type 1: Fusion of the right and left coronary cusps
- Type 2: Fusion of the right and noncoronary cusps
- Type 3: Fusion of the left and noncoronary cusps.
The most common type is the fusion of the right and left coronary cusps; less common is the fusion of the right coronary and noncoronary cusps, and the least common is the fusion of the left and noncoronary cusps (<1%).[5],[6] A newer classification was published last year and included three types and phenotypes. It divided BAV into fused BAV (90%–95%), two sinus BAV (5%–7%), and partial fusion BAV.[7]
It is well known that BAV is usually not an isolated aortic valve disease, and it can be associated with many other abnormalities. That includes but is not limited to aortic root dilatation, coarctation of the aorta, abnormalities in the coronaries, and mitral valve disease. The dilatation of the ascending aorta is the most common abnormality and is most likely due to a combination of altered flow in the aorta and cellular structural abnormality.[8]
Bacterial endocarditis has been reported with BAV, but it is not significant enough to warrant using prophylaxis antibiotics with each procedure. The coarctation of the aorta can also occur, and some reports showed more than a quarter of cases with aortic coarctation who underwent surgical repair were found to have BAV.[9] Therefore, it is recommended in the 2018 AHA/ACC congenital heart disease guidelines to screen for aortopathy and coarctation in all BAV patients.[10]
| Clinical Presentation | | |
The presentation of the BAV is quite variable. Many children with BAV are asymptomatic with normal valve function. For symptomatic children, aortic stenosis is more common, as expected. Symptoms do worsen with increasing the severity of the valve stenosis, and it can present at an early age, including fetal life. The symptoms are not specific to aortic valve disease, as children tend to present with symptoms of heart failure and failure to thrive. However, the clinical examination might be more specific with auscultation of systolic click and murmurs of aortic valve stenosis and/or incompetence.[11]
| Detailed Echocardiographic Assessment | | |
The echocardiographic assessment of the BAV should include aortic valve morphology and estimate the degree of the aortic valve dysfunction. It is also a very useful tool to monitor the dimensions of ascending aorta and aortic root, identify other lesions associated with BAV such as mitral valve disease, aortic arch lesions, and assessment of ventricular function.
The parasternal long-axis view can show an asymmetric diastolic leaflet closure line, whereas the short axis view can identify the two commissures in systole [Figure 2] and [Figure 3]. | Figure 2: The parasternal long-axis view showing asymmetric diastolic leaflet closure line and dilated ascending aorta
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 | Figure 3: The parasternal short-axis view showing two commissures in systole
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A detailed assessment should include BAV morphology, number of the cusps, commissures, raphes and the degree of their fusion, estimation of the left ventricle dimensions, wall thickness, and function. Incomplete raphes leading to partial cusp fusion might be challenging to visualize and certain cases might require transesophageal echocardiography for that.[4]
Serial measurements are needed to determine the BAV malfunction and the aortic root, and ascending aorta rate of dilation. The latter can be done by measuring the diameter of the valve annulus, root, sinotubular junction, and ascending aorta at the level of the right pulmonary artery in the parasternal long-axis view in systole.[12]
The severity of aortic valve stenosis is estimated by measuring the Doppler-derived maximum instantaneous and mean pressure gradient across the aortic valve. Mild, moderate, and severe aortic valve stenosis are defined as a peak Doppler velocity of < 3 m/s; 3–4 m/s, more than 4 m/s, respectively. Color Doppler flow mapping is useful to guide the Doppler cursor with the jet allowing optimal alignment. Echocardiographic views obtained from the suprasternal and right parasternal windows are useful to get better alignment with the direction of the aortic outflow and some authors recommend the use of the low-frequency continuous-wave (CW) nonimaging Doppler probe in smaller children. The apical three-chamber view can be used in infants and children to provide interrogation of the left ventricular (LV) outflow tract.
CW Doppler is the mode of choice for estimating the maximum instantaneous and mean pressure gradients, whereas pulsed-wave Doppler is used to determining the level of the obstruction across the LV outflow tract.[12]
The continuity equation can be used to estimate the aortic valve area in older children and in young adults. In mild aortic valve stenosis, the effective orifice area is >1.4 cm2; in moderate stenosis, it is 1.0–1.4 cm2; and in severe stenosis, it is <1.0 cm2.[13],[14] The degree of aortic valve regurgitation can be assessed by the width of the vena contracta-to-the aortic annulus diameter ratio. Vena contracta-to-aortic annular ratio is considered mild if the ratio is <one-third, moderate if the ratio is between one-third and two-third, and severe regurgitation if it is more than two-third. Aortic regurgitation jet pressure half-time, degree, and duration of flow reversal in the descending aorta are other parameters that can be used for severity estimation.[15],[16]
Transthoracic three-dimensional echocardiography is a feasible tool for better visualization of the cusp morphology and a more accurate description of a BAV in children.[17]
More published data suggest that computed tomography and magnetic resonance imaging do improve diagnostic accuracy and phenotyping of BAV morphology and aortic anatomy, and certain guidelines recommend screening for associated aortopathy at least once with these modalities.[18]
| Therapeutic Cardiac Catheterization | | |
There are two available therapies for neonates and children with aortic valve stenosis (AS) with BAV: transcatheter balloon valvuloplasty (BVP) and surgical valvotomy (commissurotomy). The BVP is accepted worldwide as a reliable and safe method for the treatment of congenital aortic stenosis, but the choice between BVP and surgical valvotomy remains the preference of the institution, based on the level of expertise, and safety and success rate.
The common clinical presentations of isolated AS requiring BVP in the pediatric population with or without BAV stenosis are:
- Newborn with critical AS (ductal dependent) or in children with systolic dysfunction of the left ventricle (Class I)
- Children with a resting peak-to-peak systolic gradient (via catheter) >50 mmHg (Class I)
- Children with resting peak-to-peak systolic gradient >40 mmHg (via catheter) with symptoms of angina, syncope, or ischemic ST-T-wave changes on electrocardiography at rest or with exercise (Class I)
- Children or adolescents with a resting peak-to-peak systolic gradient of >40 mmHg (via catheter), without symptoms or ST-T-wave changes if they wish to become pregnant or to participate in strenuous competitive sports (Class IIb)
- Asymptomatic patient with peak-to-peak systolic gradient of <50 mmHg (via catheter under anesthesia) if the nonsedated Doppler study mean gradient was >50 mmHg (Class IIb)
- BVP is not indicated in asymptomatic children with resting peak-to-peak systolic gradient of <40 mmHg (via catheter) with no ST-T-wave changes or in combination with significant aortic regurgitation that requires surgical intervention (Class III).[19]
BVP can be either an alternative or a preoperative measure to give more time to electively performing surgical therapy later on. It has been reported that up to half of the patients treated by BVP were free from surgery, and most of them have a normal systolic LV function after 10 years of follow-up.[20]
The advantages of BVP are avoidance of cardiopulmonary bypass, shorter hospitalization time, and avoidance of sternotomy, while the advantage of surgical valvotomy is a lower incidence of aortic regurgitation. The disadvantages of BVP are a higher incidence of aortic regurgitation and femoral artery thrombosis or injury, and higher residual stenosis.[21]
Access is obtained either blindly or under ultrasound guidance. Femoral artery access is more commonly used in children; however, some clinically sick infants might require a carotid artery cutdown approach. The carotid artery approach is usually kept for infants with critical aortic stenosis and reports showed shorter procedure time and fewer reported complications, especially for the femoral artery occlusion or injury.[22]
Hemodynamic studies should be done at the beginning of the procedure and after the intervention. The transaortic pressure gradient measured through the catheter is peak-to-peak gradient, and it is done through direct measurement of the systolic pressures in the left ventricle and the aorta. It can be done either with pullback the catheter from the left ventricle to the aorta or simultaneous measurements in both [Figure 4]. | Figure 4: Transaortic pressure gradient: Pressure waveforms obtained through simultaneous pressure measurement in the LV and RFA. The peak-to-peak gradient here is 62 mmHg. LV: left ventricle. RFA: right femoral artery
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Keep in mind that the pressure gradient will not be equal to the peak pressure gradient obtained before the procedure by echocardiogram. In the catheter, it is a direct measurement of peak-to-peak, while an echocardiogram estimates the peak instantaneous gradient and mean pressure gradient. However, the invasive peak-to-peak gradient measured by fluid-filled catheters sometimes corresponds well to the mean pressure gradient obtained by echocardiography.
Angiography should also be done before and after the intervention. Aortography and left ventriculography can be done. Angiograms are helpful to measure the aortic valve orifice, examine the leaflets opening, evaluate LV size and function, and quantify the aortic valve regurgitation if present. Ventriculography is usually done before the intervention and aortography after the BVP. The aortography should be done post BVP to evaluate the results and particularly to evaluate for some of the known complications like aortic regurgitation.
Rapid ventricular pacing is sometimes required for balloon stabilization and avoidance of valve injury. It is done through using a temporary pacemaker catheter inserted through the femoral vein and keeping the tip in the right ventricle. The pacing rate should be set up at 150/min and gradually increasing it to achieve a 50% decrease in systemic blood pressure and that should be tested before positioning the balloon. The pacing should be started just before the balloon inflation and continue until the balloon is deflated. Adenosine administration is another alternative if pacing cannot be done.[23] BVP is done through selecting a compliant balloon with low inflation pressure. The balloon size should be 80%–90% of the aortic valve annulus diameter. The balloon should be positioned across the aortic valve and that can be confirmed with fluoroscopy and/or echocardiography. Other anomalies such as aortic coarctation can be addressed in the same session [[Figure 5], [Figure 6], [Figure 7] and Videos 1-4]. | Figure 5: Ventriculography: Left ventriculography in a 5-year-old girl with BAV and severe AS in systole and diastole. One can appreciate the narrowed aortic valve orifice and the restricted leaflet opening [Video 1]. BAV: Bicuspid aortic valve, AS: Aortic valve stenosis
Click here to view |
 | Figure 6: BVP: Cine image of the same child in [Figure 5]. Balloon positioned across the aortic valve over an exchange length guidewire. The balloon is inflated and the waist can be appreciated. Also, the temporary pacemaker catheter can be seen with the tip in the right ventricle [Video 2]
Click here to view |
 | Figure 7: Aortography post-BVP: Aortography of the same child in [Figure 5] and [Figure 6], which shows mild aortic regurgitation postintervention
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[Additional file 1]
[Additional file 2]
[Additional file 3]
[Additional file 4]
BVP is a safe procedure with low complications rate. The following are an example of some of the reported complications:
- Rhythm disorders (5.0%): Bradycardia, ventricular tachycardia, supraventricular tachycardia, atrial flutter/fibrillation, asystole, ventricular fibrillation, and heart block. These are usually short lived and resolve spontaneously
- Arterial lesions (2.6%): Occlusion of femoral artery, femoral arterial cutdown, dissection/occlusion of the iliac artery, and intimal lesion in the aortic arch
- Cardiac lesions (1.9%): Aortic regurgitation, myocardial perforation, mitral valve lesions, and transitional myocardial ischemia.[20]
| Conclusion | | |
BAV is the most common congenital heart disease with wide variable presentations, and it can progress to more complex heart disease. Echocardiography is an essential tool for diagnosis, phenotyping, identifying valvular dysfunction, and other associated anomalies. It is also a useful tool before, during, and after cardiac catheterization and surgery and for following up on those children.
Aortic stenosis can present at any age and BVP plays an important role in treating children with aortic stenosis plus it can treat some of the associated anomalies like aortic coarctation. It remains a safe alternative and less invasive procedure with comparable results to surgical valvotomy.
Lifelong follow-up is needed for all children with BAV with or without valve dysfunction. Special attention is required for the development or progression of valve dysfunction and aortic root dilatation.
Acknowledgment
Special thanks to Maryam Al-Saloos for drawing the images in [Figure 1].
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
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