Percutaneous balloon mitral valvuloplasty

Introduction

Mitral stenosis (MS) is the most common sequelae of rheumatic heart disease and is characterized by diffuse fibrous thickening of the margins of the mitral valve (MV) leaflets and fusion of the commissures. Untreated, severe MS can lead to significant derangement of the functional status of patients and reduced long-term survival. Since its introduction in the 1980s, percutaneous balloon mitral valvuloplasty (PBMV) has proven to be an effective and durable treatment option for selected patients with rheumatic MS. Although it is more challenging, PBMV has also been utilized in patients with nonrheumatic MS (e.g., calcific MS). This chapter focuses on the contemporary indications, patient selection, and techniques of PBMV.

Indications and patient selection

PBMV is recommended for symptomatic patients with severe MS (mitral valve area [MVA] <1.5 cm ² , stage D) and favorable valve morphology in the absence of contraindications ( Fig. 14.1 ). The goal of PBMV for patients with rheumatic MS is to directly affect the main valvular pathology by inducing an effective commissural split without a significant increase in mitral regurgitation (MR). Hence, in symptomatic patients, the main determinants of patient selection for PBMV are the anatomic features of the mitral apparatus. Other considerations include the patient’s age, functional status, and the presence or absence of atrial fibrillation or pulmonary hypertension.

Patients who are being considered for PBMV should undergo a comprehensive assessment with transthoracic ± transesophageal echocardiography (TEE). The MV and subvalvular apparatus need to be systematically evaluated for favorable and unfavorable features for PBMV. Attempts have been made to incorporate certain individual characteristics into a holistic scoring system to predict optimal PBMV results. The Wilkins echocardiography score is the most commonly used scoring system for PBMV. This score incorporates four echocardiographic characteristics of the mitral apparatus, including leaflet mobility, leaflet thickness, leaflet calcification, and subvalvular thickening ( Table 14.1 ). Each component is given a 1- to 4-point score. Patients with Wilkins scores ≤8 are, in general, suitable for PBMV. When the Wilkins score is >10, the risk of complications, including severe MR requiring urgent or emergent MV replacement, is significantly higher. Patients with a Wilkins score between 8 and 10 may be considered for PBMV on an individual basis. A simpler scoring system is the Lung and Cormier score, which divides the valvular anatomy into three groups, with patients in group 1, 2, and 3 considered optimal, intermediate, and borderline candidates for PBMV, respectively ( Table 14.2 ). Newer scoring systems to predict PBMV outcomes have been proposed. ^, These scores incorporate novel predictors of PBMV outcomes, such as commissural morphology, leaflet displacement, commissural calcium, and commissural fusion. These scoring systems have weaknesses and strengths. One fundamental criticism applying to all scoring systems is that they are mainly derived from single-center experience and with a limited number of operators. Furthermore, assessment of the subvalvular apparatus is difficult in most patients, despite TEE. Most of the echocardiographic assessments are qualitative, which makes the reproducibility of a specific scoring system more challenging. Nevertheless, using any of these scoring systems might help the operator in predicting the outcome and potential complications that should be discussed with the patient as part of the informed consent and shared decision-making.

Contraindications to PBMV

The presence of greater-than-moderate MR is considered an absolute contraindication to PBMV. Relative contraindications include a Wilkins score >10, left atrial or left atrial appendage thrombus, severe or bicommissural calcification, absence of bicommissural fusion, severe mitral annular calcification, international normalized ratio (INR) >1.5 or bleeding diathesis, and other significant coronary or valvular pathology requiring surgery.