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FIG 42.37 Adult patient undergoing balloon pulmonary valvuloplasty for moderate pulmonary valve stenosis Note the somewhat unremarkable appearance of the right ventricular outflow tract prior to valvuloplasty (A), with notable subpulmonary narrowing after relief of the valvar obstruction (B) FIG 42.38 Pulmonary valvar gradients before, immediately after, and late after balloon pulmonary valvuloplasty (From Sadr-Ameli MA, Sheikholeslami F, Firoozi I, et al Late results of balloon pulmonary valvuloplasty in adults Am J Cardiol 1998;82:398–400.) Data on the incidence and risk factors for moderate to severe pulmonary regurgitation after pulmonary balloon valvuloplasty are limited Devanagondi and colleagues reported an incidence of 60% of patients having at least moderate pulmonary regurgitation at a median follow-up of 15.1 years.145 In multivariate analysis, only a body surface area below 0.3 m2 was identified as an independent risk factor for at least moderate pulmonary regurgitation after balloon pulmonary valvuloplasty The problem though with this study as with many others is the incomplete availability of data and, most importantly, the fact that the degree of pulmonary regurgitation is usually assessed by echocardiography rather than cardiovascular MRI As such, it is difficult to draw any firm conclusions from those retrospective studies One of the most comprehensive recent studies to evaluate the prevalence and predictors of pulmonary regurgitation after balloon pulmonary valvuloplasty as well as exercise tolerance was reported as a prospective single-center study by Harrild and colleagues.146 The study included 41 patients that underwent cardiac magnetic resonance imaging and exercise testing at a median of 13.1 years after balloon pulmonary valvuloplasty The results documented that 34% of patients had a pulmonary regurgitant fraction greater than 15%, right ventricular dilation with a z-score of 2 or greater was present in 40% of patients, and a z-score of 4 or greater was present in 11% of patients Peak oxygen consumption (VO2) was below average (92% ± 17%) It is important though to bear in mind that exercise performance is multifactorial Larry Latson pointed out in an editorial related to this article that among many cardiovascular factors this also includes genetic makeup, conditioning and motivation.147 Similarly, Guo and colleagues reported a reduced exercise capacity after balloon pulmonary valvuloplasty of about 90% when compared with healthy children, with similar concerns relating to conditioning and other factors that could influence these results.148 It is important to note that the study by Harrild and colleagues also found that the pulmonary regurgitant fraction was significantly associated with the balloonto-annulus ratio.146 However, the data also found that there is no “safe” ratio below which moderate to severe pulmonary regurgitation can be avoided altogether, and no ratio above which one would automatically expect moderate to severe pulmonary insufficiency As Latson identified, the findings do not address the problem of what to do when a more conservative use of a balloon size results in significant residual stenosis.147 Having said this, it is probably reasonable to be more conservative initially using a balloon to annulus ratio of not much more than 1.2 : 1, rather than the 1.2 to 1.4 that earlier studies suggested Pathak and colleagues compared the results of patients in whom a ratio of 1.2 or less was chosen to those of more than 1.2 and found no significant difference in the gradient reduction between the two groups.149 Surgery as Opposed to Balloon Dilation Comparing long-term surgical and transcatheter outcome data is difficult and inconclusive at this time Although data on the long-term need for reinterventions for residual pulmonary stenosis are available for both the surgical and the transcatheter group, long-term data on the need for reinterventions as a result of pulmonary regurgitation are limited Furthermore, even though singlecenter data are available for each of the treatment modalities, very few studies have published direct comparisons between surgical and transcatheter therapy In a large series of 170 patients in a single Dutch center, direct comparison between surgical valvotomy and balloon dilation was possible.150 Surgical relief of pulmonary stenosis yielded lower long-term gradients and a longer freedom from reintervention (Fig 42.39) However, mean follow-up of the surgical group was just 9.8 years Voet and colleagues recently compared a cohort of 79 surgically treated patients with 139 patients that underwent balloon pulmonary valvuloplasty.151 The median follow-up for the surgical group was 22.5 years and for the transcatheter group 6.0 years The overall need for reintervention in the surgical group was 20.3% (none for residual pulmonary stenosis), and 9.4% after balloon pulmonary valvuloplasty (85% for residual pulmonary valve stenosis) Freedom from reintervention at 5 and 10 years for the surgical group was 93.5% and 87%, respectively, and for the transcatheter group 87.5% and 84.4%, respectively