Pulmonary valvuloplasty
Background
Pulmonary valve stenosis (PS) is a common form of congenital heart disease that may present at any age, but often in infancy or early childhood in its more severe forms. The adult patient with PS tends to have more clinical symptoms than a child with a similar degree of PS; gradients can be progressive, often due to acquired right ventricular outflow tract (RVOT) infundibular muscle hypertrophy. The patient with an interatrial communication (patent foramen ovale/atrial septal defect [PFO/ASD]) may experience a right-to-left shunt as right ventricular hypertrophy progresses and compliance decreases. Percutaneous pulmonary balloon angioplasty (PBA) has been performed safely and effectively since 1982 with low morbidity and mortality. Acute success rates for PBA are reported to be between 80% and 90%, with potential for ongoing reduction in gradient due to spontaneous resolution of infundibular hypertrophy. However, the patient may require beta-blocker therapy as RVOT obstruction resolves.
Indications for intervention
Indications for intervention typically include the following: (1) pulmonary valve mean gradient by Doppler ≥35 to 40 mmHg and (2) symptomatic functional limitation. Favorable anatomy includes a normal pulmonary valve annulus with thin, doming pulmonary valve leaflets, and post-stenotic main pulmonary artery dilation. A thickened, dysplastic pulmonary valve with hypoplastic annulus and/or no evidence of main pulmonary artery dilation is much less likely to respond favorably to PBA, although some degree of reduction in valve gradient may provide symptomatic relief in the adult.
AHA recommendations
| In adults with moderate or severe valvular pulmonary stenosis and otherwise unexplained symptoms of heart failure, cyanosis from interatrial right-to-left communication, and/or exercise intolerance, balloon valvuloplasty is recommended | I | B-NR |
| In asymptomatic adults with severe valvular pulmonary stenosis, intervention is reasonable | IIa | C-EO |
Preprocedural imaging
Transthoracic echo is usually sufficient for diagnosis and can be reliable in determining the pulmonary valve gradient (mean Doppler gradient typically correlates best with peak-to-peak systolic gradient measured at cardiac catheterization). The nature of the pulmonary valve leaflets should be determined (i.e., thickened, dysplastic). The pulmonary valve annulus should be evaluated carefully and measured to provide guidance in balloon selection. In the adult patient with challenging acoustic windows, transesophageal echo or computed tomography can be considered (particularly to evaluate infundibular anatomy, anatomy of the main pulmonary artery, or pulmonary branch arteries if other stenotic lesions are suspected).
Basic procedure
Standard right heart catheterization is performed to document the pulmonary valve gradient. The use of two femoral venous sheaths allows simultaneous right ventricular (RV) and pulmonary artery (PA) pressure measurement, in addition to providing immediate postvalvuloplasty RV systolic pressure assessment if a single-balloon dilation is planned. Initial RV angiogram confirms the anatomy of the RVOT, and a carefully calibrated measurement of the pulmonary annulus should be performed at the hinge point of the valve leaflets (also correlating with the annulus as measured by echocardiography). Straight lateral plane imaging is most accurate for annulus measurement ( Fig. 28.1 ). A stiff 0.035″ exchange wire is positioned deep within the PA over which the balloon can be stabilized in the annulus. For the single-balloon technique, a balloon approximately 120% of the pulmonary annulus is chosen ( Fig. 28.2 A); for a double-balloon angioplasty, the combined diameters of the two balloons should be 1.5 to 1.7 times the annulus diameter (see Fig. 28.2 B). Alternatively, for the adult patient, the Inoue balloon may be used for pulmonary valve dilation, again with a diameter 120% of the annulus. Controlled balloon inflation should allow positioning within the leaflets; once stable, full inflation can be performed. Double balloons may be more difficult to stabilize, and rarely is pacing needed for stabilization. A pressure-monitored inflation device should be used—high-pressure balloons are not needed. Careful pullback with an end-hole catheter after PBA may demonstrate the residual gradient below the valve due to the RVOT muscle. A postdilation RV angiogram should be performed and may reveal the typical appearance of subvalvular obstruction after successful balloon valvuloplasty ( Fig. 28.3 ).
Tips:
- 1.
Care to achieve a stable, deep wire position will be beneficial for balloon stabilization during valvuloplasty.
- 2.
If there is significant resistance when advancing the valvuloplasty balloon through the tricuspid valve, one should consider potential wire entrapment within the tricuspid chordal apparatus. In this situation the existing guidewire should be removed and the tricuspid valve recrossed, preferably with a balloon-tipped catheter (balloon inflated) to establish a different wire position.
- 3.
Balloon stability during inflation may be challenging. Adequate forward pressure on both the balloon and wire is necessary, but if the balloon starts to “milk” forward through the valve, additional forward pressure on the wire can be used to stabilize balloon position. Longer balloons are recommended (4.0 cm).
Postprocedure
Initial noninvasive echocardiography should be performed to evaluate the pulmonary valve gradient, RVOT infundibular gradient, and degree of pulmonary regurgitation. As noted, RVOT infundibular gradients typically subside over time, and patients may be treated with beta-blocker therapy. Approximately 10% of patients require additional treatment if the initial valvuloplasty is successful. Pulmonary regurgitation is usually well tolerated. The long-term outcome is very good.
Transcatheter pulmonary valve replacement
Background
RVOT intervention is common in the surgical treatment of patients with congenital heart disease (CHD), such as those with tetralogy of Fallot (TOF), pulmonary valve atresia/ventricular septal defect, truncus arteriosus, and transposition of the great arteries. In addition, patients who have undergone RVOT conduit placement, such as the Ross procedure, often require later RVOT conduit revision. Inevitably, conduit failure, valve deterioration (stenosis and/or insufficiency), or progressive pulmonary insufficiency in the setting of transannular patch therapy will drive the need for pulmonary valve insertion. Transcatheter pulmonary valve replacement (TPVR) is appealing in patients with CHD, as many have been subjected to more than one median sternotomy procedure, and the overall goal in approaching patients with complex CHD is to avoid multiple redo median sternotomies. TPVR therapy is now an important part of intervention for patients with both congenital and acquired pulmonary valve dysfunction, and this type of intervention should be performed by a pediatric interventional specialist or as part of a multidisciplinary structural heart team that includes an experienced pediatric congenital interventionalist.
Indications for intervention
Typical guidelines for consideration of TPVR are similar to those for surgical pulmonary valve replacement. Moderate-to-severe RVOT obstruction (mean Doppler gradient >35 to 40 mmHg), moderate-to-severe pulmonary regurgitation, presence of clinical symptomatology/New York Heart Association (NYHA) functional status, arrhythmia burden, and RV size and function should be evaluated when deciding to proceed with TPVR. Two systems are currently approved in the United States by the Food and Drug Administration (FDA) for treatment of dysfunctional surgical RVOT conduits or bioprosthetic valves: Melody (Medtronic, Inc. Minneapolis, MN, approved in 2010) and Edwards Sapien XT (Edwards Lifesciences, Inc., Irvine, CA, approved in 2016). However, it is estimated that only a small percentage of patients in need of RVOT therapy may be suitable for currently approved TPVR systems. Therefore off-label use of currently approved systems is commonplace. Clinical trials are being conducted to evaluate the Edwards Sapien 3 valve in the pulmonary position, as are trials of newly designed self-expanding stented valve systems to treat the dilated “native” RVOT with severe pulmonary regurgitation (such as the Alterra Adaptive Prestent [Edwards] designed for Sapien implant and the Harmony Valve [Medtronic, Inc].
AHA guidelines
| Recommendations in TOF | ||
| Pulmonary valve replacement (surgical or percutaneous) for relief of symptoms is recommended for patients with repaired TOF and moderate or greater pulmonary regurgitation (PR) with cardiovascular symptoms not otherwise explained | I | B-NR |
| Pulmonary valve replacement (surgical or percutaneous) is reasonable for preservation of ventricular size and function in asymptomatic patients with repaired TOF and ventricular enlargement or dysfunction and moderate or greater PR | IIa | B-NR |
| Recommendations in Isolated PR After Repair of PS | ||
| In symptomatic patients with moderate or greater PR resulting from treated isolated pulmonary stenosis with RV dilatation or RV dysfunction, pulmonary valve replacement is recommended | I | C-EO |
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