Background
Aortic stenosis (AS) is common in the elderly population, with a prevalence of approximately 3% in patients over 75 years old. The prognosis of symptomatic severe AS is poor, with a 50% mortality rate at 2 years; therefore valve replacement is usually recommended once symptoms of shortness of breath, heart failure, or angina occur.
In the majority of elderly patients, the aortic valve is trileaflet ( Fig. 6.1 , left panel ). Patients with severe AS below the age of 65 usually have a congenital bicuspid aortic valve (see Fig. 6.1 , central panel ). In both cases, the aortic valve becomes progressively calcified with age and leaflet movement is restricted. Rheumatic heart disease may cause premature calcification of the aortic and/or other valves (see Fig. 6.1 , right panel ).
Indications
Balloon aortic valvuloplasty (BAV) is designed to fissure or fracture the calcified aortic valve and separate fused commissures. The role of BAV depends on the specific clinical setting. In congenital AS where the valve is not significantly calcified, benefits are usually quite durable and it is an accepted destination therapy. This is different to elderly patients with severe calcific degenerative AS in whom BAV is largely performed as a palliative procedure or a bridge to aortic valve replacement (AVR)/or transcatheter aortic valve replacement (TAVR).
The reluctance to perform BAV in calcific AS relates to the fact that the injury caused by the balloon also promotes progressive collagenization and formation of new scar tissue, leading to short-lived reduction in aortic gradients and valve area. Symptomatic improvement may persist for up to 6 to 12 months in selected cases after BAV, but the mortality remains high and similar to untreated patients. Restenosis usually occurs within 6 to 12 months of BAV in calcific AS, and results are not durable ( Box 6.1 ).
Other potential indications
There are no class I indications for BAV because it has not been shown to have lasting benefits in any disease state.
Young patients with congenital aortic stenosis
In young patients with congenital AS, BAV may be considered as a therapeutic option. It is thought to have a more durable effect in younger patients who do not have significant valvular calcification; however, valve replacement is typically offered as first line. If this is not feasible, BAV may be considered in the following situations:
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Young patients with symptomatic AS and peak gradient ≥50 mmHg
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Young patients with asymptomatic AS and peak gradient ≥60 mmHg
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Young patients with asymptomatic severe AS who are considering pregnancy
Patients with calcific degenerative aortic stenosis
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As a palliative procedure for symptomatic benefit (included in European Society of Cardiology [ESC] but not American Heart Association [AHA] guidelines)
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To facilitate urgent noncardiac surgery (included in ESC but not AHA guidelines)
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Cardiogenic shock in a patient with severe calcific AS who has been turned down for immediate surgical AVR/TAVR
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As a trial of therapy in a symptomatic patient with severe AS and other comorbidities that may cause shortness of breath (e.g., chronic obstructive pulmonary disease [COPD], severe left ventricular [LV] dysfunction). In this setting BAV may help in deciding whether the patient’s symptoms are cardiac or noncardiac.
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As a trial of safety of TAVR therapy in patients with low coronary heights, particularly in the situation of previous AVR with externally mounted leaflets (e.g., Mitraflow prosthesis)
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For treatment of large paravalvular leaks after TAVR insertion (usually during the same procedure as the initial TAVR)
Contraindications to BAV
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Active endocarditis
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Moderate or severe aortic regurgitation
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Contraindications to systemic heparinization
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LV thrombus (because LV wire placement is required)
The role of BAV in patients who are currently not suitable for TAVR is growing. Many centers will consider BAV as a “trial of therapy” where symptomatic benefit from TAVR is uncertain. For example, patients with poor LV function, where it is unclear if there will be ventricular recovery after valve replacement, may undergo a BAV and then be reevaluated for suitability for TAVR/AVR if the LV function or symptoms improve after the BAV. Similarly, in patients with severe AS and other comorbidities that cause shortness of breath (e.g., COPD), the potential symptomatic benefit, if any, from TAVR is difficult to estimate. In some cases, a therapeutic trial of BAV may be performed to see if the patient would benefit from TAVR. For timing of such interventions, because the durability of symptomatic improvement after BAV may be short-lived, once symptomatic benefit is confirmed, TAVR should be performed within 1 to 2 months of the BAV.
Procedural risks
Procedure risks for BAV are estimated between 4% to 6% in contemporary registries, including death (estimated at 1%), myocardial infarction (MI), stroke (1% to 2%), vascular damage, cardiac tamponade, arrhythmia (including need for a permanent pacemaker), and annular rupture/aortic dissection/ventricular perforation requiring emergency cardiothoracic surgery.
Technique
Balloon sizing
Before the procedure, the size of balloon for the valvuloplasty should be selected based on the results of preprocedural imaging. If cross-sectional computed tomography (CT) has been performed (e.g., as part of a transcatheter aortic valve implantation [TAVI] workup), the cross-sectional area and diameter of the aortic annulus can be measured ( Fig. 6.2 ). If CT is not available, transthoracic echocardiography (TTE) can be used ( Fig. 6.3 ).
