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Aortic Valvular Stenosis

  • Xiangbin Pan
Chapter

Abstract

Congenital aortic stenosis (CAS) is a relatively common congenital heart disease (1.1–4.3 per 10,000 live births). The aortic annulus of patients with CAS is usually hypoplastic to some extent; the leaflets are thickened, and the commissures, to different degrees, are fused. Usually newborns with critical CAS suffer from low cardiac output and shock secondary to poor left ventricular function. In older children and adolescents with severe CAS, the main symptoms are angina chest pain, syncope and dyspnea, or other symptoms of heart failure such as orthopnea, paroxysmal nocturnal dyspnea, and pedal edema. Currently, percutaneous balloon valvuloplasty has become an important procedure for the treatment of CAS.

Congenital aortic stenosis (CAS) is a relatively common congenital heart disease (1.1–4.3 per 10,000 live births). The aortic annulus of patients with CAS is usually hypoplastic to some extent; the leaflets are thickened, and the commissures, to different degrees, are fused. Usually newborns with critical CAS suffer from low cardiac output and shock secondary to poor left ventricular function. In older children and adolescents with severe CAS, the main symptoms are angina chest pain, syncope and dyspnea, or other symptoms of heart failure such as orthopnea, paroxysmal nocturnal dyspnea, and pedal edema. Currently, percutaneous balloon valvuloplasty has become an important procedure for the treatment of CAS.

10.1 Indication for Treatment

  • Regardless of valve gradient, the newborn with isolated critical CAS is ductal dependent or children with isolated CAS have depressed left ventricular systolic function.

  • Patients with isolated CAS have a resting peak systolic valve gradient of >50 mmHg by catheter or ≧75 mmHg.

  • Patients with isolated CAS have a resting peak systolic valve gradient (by catheter) of >40 mmHg if there are symptoms of angina or syncope or ischemic ST-T-wave changes on electrocardiography at rest or with exercise.

10.2 Preprocedure Imaging and Preparation

  • Echocardiography can provide the following information: the morphology of the aortic valve, peak instantaneous and mean aortic valve gradient by Doppler, aortic valve annulus diameter (Fig. 10.1) and z-score, left ventricular dimensions, left ventricular shortening fraction and ejection fraction, severity of aortic valve regurgitation, and other lesions (Fig. 10.2a, b)

  • Hemodynamic assessments: pressure in the left ventricle and ascending aorta (Fig. 10.3)

  • Aortic angiography: depicting the details of the valve anatomy and assessing the aortic annulus diameter between the hinge points of the valve leaflets (Fig. 10.4)

Fig. 10.1

Echocardiographic measurement of the aortic valve annulus between the hinge points of the valve leaflets (double-headed arrows) in the parasternal long-axis view

Fig. 10.2

Transesophageal echocardiography demonstrates a 2-month-old girl (patient 1) with CAS. The aortic valve annulus is 8.7 mm (a). Although the peak systolic aortic valve gradient is about 52 mmHg, the ejection fraction is 31% with poor left ventricular function (b)

10.3 Catheter Intervention

  • Wires and balloon catheter (Fig. 10.5) can pass through the aortic valve from either the aorta (retrograde approach) or the left ventricle (antegrade approach). The retrograde approach is the most common method used for puncturing femoral artery or the umbilical artery in newborns. The antegrade approach is an alternative way by using a femoral venous access or an umbilical vein when the guidewire cannot cross a severely stenotic aortic valve from the retrograde approach.

  • The techniques of valvuloplasty include single- (Fig. 10.6) and double-balloon valvuloplasty. Compared with single-balloon (Fig. 10.7) valvuloplasty, double-balloon valvuloplasty has the advantages of improved gradient relief, less vessel trauma, and smaller risk of completely occluding left ventricular outflow.

  • In single-balloon valvuloplasty, the balloon-to-annulus ratio should be less than 1:1. Start with a balloon diameter of about 80% of the aortic annulus and increase its size by 1 mm. But in double-balloon valvuloplasty, each balloon has a similar diameter and length, so the ratio of the sum to the valve annulus diameter is about 1:3.

  • Advance a balloon valvotomy catheter over the guidewire, straddle the valve into the correct position, and inflate with a pressure of 4–7 ATM until the balloon waist disappears. Each inflation-deflation period lasts no more than 5–10 s. Temporary rapid pacing is performed by putting a bipolar pacing catheter in the right ventricular apex and using VVI pacing at a rate of 220–240 impulses per minute during the balloon inflation.

10.4 Assessment of Success (Fig. 10.8)

  • More than 50% decrease in pressure gradient across the aortic valve and no significant aortic regurgitation.

  • A residual gradient of <30 mmHg is usually aimed.

10.5 Complications

  • Aortic regurgitation is a potentially serious complication. About 15% of patients experience moderate or severe aortic regurgitation after balloon valvuloplasty.

  • Vascular complications: especially in newborns in which femoral artery access is used.

  • Arrhythmia: transient bradycardia and left bundle-branch block and premature beats.

  • Cardiac structural damage: mitral valve tears, annulus tears, and heart perforation.

  • Death: a dilated balloon may completely block the blood flow in the aorta and induce fatal ventricular fibrillation and asystole. The early mortality rate is about 4%.

Fig. 10.3

Patient 1: Left ventricular angiography in posterior-anterior projection shows CAS, and the ascending aorta is significantly expanded

Fig. 10.4

The aortic valve annulus is measured by aortography in posterior-anterior projection. The double-headed arrow indicates the aortic annulus diameter between the hinge points of the valve leaflets

Fig. 10.5

Tyshak and Tyshak II (NuMED, Inc.) provide a wide range of balloon diameters, from 4 to 30 mm, with 1-mm increments up to 25 mm (except 21 and 24 mm). Tyshak can better resist the left ventricular ejection power and is therefore preferred in older children. Tyshak II is preferable in infants in whom the lowest possible introducer profile is important. Tyshak Mini usually applies to neonates

Fig. 10.6

Patient 1: Advance an 8 mm × 20 mm Tyshak II balloon valvotomy catheter over the guidewire, straddle the valve into the correct position by retrograde approach, and inflate with a pressure of 4–7 ATM until the balloon waist disappears

Fig. 10.7

Patient 2: Double-balloon technique in posterior-anterior projections applied in a 1-year-old patient. The aortic valve was dilated by simultaneous inflation of two 6 mm × 20 mm Tyshak II balloon valvotomy catheters introduced into the valve from both the femoral arteries

Fig. 10.8

Patient 1: Postoperative transesophageal echocardiography demonstrates the peak systolic aortic valve gradient is about 16.5 mmHg. The ejection fraction increased significantly to 62% immediately

Supplementary material

Video 1

Angiography in the left anterior oblique (LAO) in the ascending aorta from a right internal carotid artery approach. Blood accelerating through the stenotic aortic valve is seen as a negative jet within the contrast dye injected in the ascending aorta (WMV 2368 kb)

Video 2

Left ventricular angiography in LAO showing a hypertrophic left ventricle and dysplastic and thick aortic valve. Mitral valve is seen as a negative scado on the right of the aortic valve (WMV 2240 kb)

Video 3

Fluoroscopy showing balloon inflation. The guidewire is looped within the left ventricle. During balloon inflation, waist appears at the level of the aortic valve. When the balloon is fully inflated and valve well opened, the waist disappears (WMV 2304 kb)

Video 4

Left ventricular angiography in LAO after balloon dilation. The left ventricle is hyperdynamic and hypertrophic. The apex of the left ventricle is almost completely filled by the muscle during systole. The aortic valve shows a significantly improved opening. No signs of extravasation are seen (WMV 1632 kb)

Video 5

Ascending aortography in LAO after valvuloplasty. The injection is performed with an over the wire approach. No aortic regurgitation is seen (WMV 1536 kb)

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  • Xiangbin Pan
    • 1
  1. 1.Department of Cardiovascular SurgeryNational Center for Cardiovascular Disease, China & Fuwai HospitalBeijingChina

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